query: The cytokine receptor which regulates chemotaxis and formation of lymph nodes is involved in production of myeloperoxidase in the left atrium.

title: Myeloperoxidase acts as a profibrotic mediator of atrial fibrillation

text: Observational clinical and ex vivo studies have established a strong association between atrial fibrillation and inflammation. However, whether inflammation is the cause or the consequence of atrial fibrillation and which specific inflammatory mediators may increase the atria's susceptibility to fibrillation remain elusive. Here we provide experimental and clinical evidence for the mechanistic involvement of myeloperoxidase (MPO), a heme enzyme abundantly expressed by neutrophils, in the pathophysiology of atrial fibrillation. MPO-deficient mice pretreated with angiotensin II (AngII) to provoke leukocyte activation showed lower atrial tissue abundance of the MPO product 3-chlorotyrosine, reduced activity of matrix metalloproteinases and blunted atrial fibrosis as compared to wild-type mice. Upon right atrial electrophysiological stimulation, MPO-deficient mice were protected from atrial fibrillation, which was reversed when MPO was restored. Humans with atrial fibrillation had higher plasma concentrations of MPO and a larger MPO burden in right atrial tissue as compared to individuals devoid of atrial fibrillation. In the atria, MPO colocalized with markedly increased formation of 3-chlorotyrosine. Our data demonstrate that MPO is a crucial prerequisite for structural remodeling of the myocardium, leading to an increased vulnerability to atrial fibrillation.

title: The surgical anatomy of the conduction tissues.

text: On the basis of our collective experience we have reviewed the disposition of the cardiac conduction tissues as they might be observed by the surgeon in both normal and abnormal hearts. The sinus node lies subepicardially in the terminal sulcus; because of its variable blood supply the entire superior cavoatrial junction is a potential danger area. There are no morphologically discrete tracts extending through the atrial tissues between sinus and atrioventricular nodes. The atrioventricular node, the atrial extent of the atrioventricular conduction axis, is contained exclusively within the triangle of Koch. The axis penetrates through the central fibrous body and branches on the muscular ventricular septum immediately beneath the interventricular component of the membranous septum. The landmarks to these structures are described as they might be seen through the right atrium, left atrium, and aorta. Consideration is then given to the surgical anatomy of the abnormal muscular atrioventricular connections that underscore the ventricular pre-excitation syndromes. Finally, rules are developed whereby the disposition of the conduction tissues can be predicted with accuracy in congenitally malformed hearts, in the settings of both normal and abnormal chamber connections. The most important variables in this respect are alignment between the atrial and ventricular septal structures and the pattern of ventricular architecture present.

title: CD169+ MACROPHAGES PRESENT LIPID ANTIGENS TO MEDIATE EARLY ACTIVATION OF INVARIANT NKT CELLS IN LYMPH NODES

text: Invariant natural killer T cells (iNKT cells) are involved in the host defense against microbial infection. Although it is known that iNKT cells recognize glycolipids presented by CD1d, how and where they encounter antigen in vivo remains unclear. Here we used multiphoton microscopy to visualize the dynamics and activation of iNKT cells in lymph nodes. After antigen administration, iNKT cells became confined in a CD1d-dependent manner in close proximity to subcapsular sinus CD169(+) macrophages. These macrophages retained, internalized and presented lipid antigen and were required for iNKT cell activation, cytokine production and population expansion. Thus, CD169(+) macrophages can act as true antigen-presenting cells controlling early iNKT cell activation and favoring the fast initiation of immune responses.

title: Human Cytomegalovirus-Encoded Interleukin-10 Homolog Inhibits Maturation of Dendritic Cells and Alters Their Functionality

text: Interleukin-10 (IL-10) suppresses the maturation and cytokine production of dendritic cells (DCs), key regulators of adaptive immunity, and prevents the activation and polarization of naïve T cells towards protective gamma interferon-producing effectors. We hypothesized that human cytomegalovirus (HCMV) utilizes its viral IL-10 homolog (cmvIL-10) to attenuate DC functionality, thereby subverting the efficient induction of antiviral immune responses. RNA and protein analyses demonstrated that the cmvIL-10 gene was expressed with late gene kinetics. Treatment of immature DCs (iDCs) with supernatant from HCMV-infected cultures inhibited both the lipopolysaccharide-induced DC maturation and proinflammatory cytokine production. These inhibitory effects were specifically mediated through the IL-10 receptor and were not observed when DCs were treated with supernatant of cells infected with a cmvIL-10-knockout mutant. Incubation of iDCs with recombinant cmvIL-10 recapitulated the inhibition of maturation. Furthermore, cmvIL-10 had pronounced long-term effects on those DCs that could overcome this inhibition of maturation. It enhanced the migration of mature DCs (mDCs) towards the lymph node homing chemokine but greatly reduced their cytokine production. The inability of mDCs to secrete IL-12 was maintained, even when they were restimulated by the activated T-cell signal CD40 ligand in the absence of cmvIL-10. Importantly, cmvIL-10 potentiates these anti-inflammatory effects, at least partially, by inducing endogenous cellular IL-10 expression in DCs. Collectively, we show that cmvIL-10 causes long-term functional alterations at all stages of DC activation.

title: Myeloperoxidase: friend and foe.

text: Neutrophilic polymorphonuclear leukocytes (neutrophils) are highly specialized for their primary function, the phagocytosis and destruction of microorganisms. When coated with opsonins (generally complement and/or antibody), microorganisms bind to specific receptors on the surface of the phagocyte and invagination of the cell membrane occurs with the incorporation of the microorganism into an intracellular phagosome. There follows a burst of oxygen consumption, and much, if not all, of the extra oxygen consumed is converted to highly reactive oxygen species. In addition, the cytoplasmic granules discharge their contents into the phagosome, and death of the ingested microorganism soon follows. Among the antimicrobial systems formed in the phagosome is one consisting of myeloperoxidase (MPO), released into the phagosome during the degranulation process, hydrogen peroxide (H2O2), formed by the respiratory burst and a halide, particularly chloride. The initial product of the MPO-H2O2-chloride system is hypochlorous acid, and subsequent formation of chlorine, chloramines, hydroxyl radicals, singlet oxygen, and ozone has been proposed. These same toxic agents can be released to the outside of the cell, where they may attack normal tissue and thus contribute to the pathogenesis of disease. This review will consider the potential sources of H2O2 for the MPO-H2O2-halide system; the toxic products of the MPO system; the evidence for MPO involvement in the microbicidal activity of neutrophils; the involvement of MPO-independent antimicrobial systems; and the role of the MPO system in tissue injury. It is concluded that the MPO system plays an important role in the microbicidal activity of phagocytes.

title: Chimeric Antigen Receptor-Redirected Regulatory T Cells Suppress Experimental Allergic Airway Inflammation, a Model of Asthma

text: Cellular therapy with chimeric antigen receptor (CAR)-redirected cytotoxic T cells has shown impressive efficacy in the treatment of hematologic malignancies. We explored a regulatory T cell (Treg)-based therapy in the treatment of allergic airway inflammation, a model for asthma, which is characterized by an airway hyper-reactivity (AHR) and a chronic, T helper-2 (Th2) cell-dominated immune response to allergen. To restore the immune balance in the lung, we redirected Tregs by a CAR toward lung epithelia in mice upon experimentally induced allergic asthma, closely mimicking the clinical situation. Adoptively transferred CAR Tregs accumulated in the lung and in tracheobronchial lymph nodes, reduced AHR and diminished eosinophilic airway inflammation, indicated by lower cell numbers in the bronchoalveolar lavage fluid and decreased cell infiltrates in the lung. CAR Treg cells furthermore prevented excessive pulmonary mucus production as well as increase in allergen-specific IgE and Th2 cytokine levels in exposed animals. CAR Tregs were more efficient in controlling asthma than non-modified Tregs, indicating the pivotal role of specific Treg cell activation in the affected organ. Data demonstrate that lung targeting CAR Treg cells ameliorate key features of experimental airway inflammation, paving the way for cell therapy of severe allergic asthma.

title: Apoptosis occurs predominantly in bystander cells and not in productively infected cells of HIV- and SIV-infected lymph nodes

text: Although 13 years have passed since identification of human immunodeficiency virus-1 (HIV-1) as the cause of AIDS, we do not yet know how HIV kills its primary target, the T cell that carries the CD4 antigen. We and others have shown an increase in the percentage of apoptotic cells among circulating CD4+ (and CD8+) T cells of HIV-seropositive individuals and an increase in frequency of apoptosis with disease progression. However, it is not known if this apoptosis occurs in infected or uninfected T cells. We show here, using in situ labelling of lymph nodes from HIV-infected children and SIV-infected macaques, that apoptosis occurs predominantly in bystander cells and not in the productively infected cells themselves. These data have implications for pathogenesis and therapy, namely, arguing that rational drug therapy may involve combination agents targeting viral replication in infected cells and apoptosis of uninfected cells.

title: Reduced expression of oestrogen receptor beta in invasive breast cancer and its re-expression using DNA methyl transferase inhibitors in a cell line model.

text: To gain insights into the possible role of oestrogen receptor (ER) beta in breast carcinogenesis, immunohistochemical analysis of ER beta was performed on 512 breast specimens encompassing normal (n = 138), pure ductal carcinoma in situ (n = 16), invasive cancers (n = 319), lymph node metastases (n = 31), and recurrences (n = 8). Real-time polymerase chain reaction (PCR) was used to investigate the methylation status of the ER beta gene in the ER beta negative breast cancer cell lines SkBr3 and MDA-MB-435. A gradual reduction in, but not a complete loss of, ER beta expression was observed during the transition from normal and pre-invasive lesions to invasive cancers, where ER beta was lost in 21% of cases. This was more pronounced in invasive ductal than in lobular carcinomas, a significantly higher proportion of which were ER beta-positive (74% compared with 91%, respectively, p = 0.0004). Examination of paired primary cancers with their axillary lymph node metastases showed that if ER beta was present in the primary tumour, it persisted in the metastasis. Treatment of ER beta-negative cell lines with DNA methyl transferase inhibitors restored ER beta expression, providing experimental evidence that silencing of ER beta in breast carcinomas could be due to promoter hypermethylation. These results suggest that loss of ER beta expression is one of the hallmarks of breast carcinogenesis and that it may be a reversible process involving methylation.

title: Interleukin 6 plays a key role in the development of antigen-induced arthritis.

text: To investigate the direct role of interleukin (IL) 6 in the development of rheumatoid arthritis, IL-6-deficient (IL-6 -/-) mice were backcrossed for eight generations into C57BL/6 mice, a strain of mice with a genetic background of susceptibility for antigen-induced arthritis (AIA). Both histological and immunological comparisons were made between IL-6-deficient (IL-6 -/-) mice and wild-type (IL-6 +/+) littermates after the induction of AIA. Although all IL-6 +/+ mice developed severe arthritis, only mild arthritis was observed in IL-6 -/- mice. Safranin O staining demonstrated that articular cartilage was well preserved in IL-6 -/- mice, whereas it was destroyed completely in IL-6 +/+ mice. In addition, comparable mRNA expression for both IL-1beta and tumor necrosis factor alpha, but not for IL-6, was detected in the inflamed joints of IL-6 -/- mice, suggesting that IL-6 may play a more crucial role in cartilage destruction than either IL-1beta or tumor necrosis factor alpha. In immunological comparisons, both antigen-specific in vitro proliferative response in lymph node cells and in vivo antibody production were elicited in IL-6 -/- mice, but they were reduced to less than half of that found in IL-6 +/+ mice. Lymph node cells of IL-6 -/- mice produced many more Th2 cytokines than did IL-6 +/+ mice with either antigen-specific or nonspecific stimulation in in vitro culture. Taken together, these results indicate that IL-6 may play a key role in the development of AIA at the inductive as well as the effector phase, and the blockade of IL-6 is possibly beneficial in the treatment of rheumatoid arthritis.

title: Apoptosis in breast cancer: relationship with other pathological parameters.

text: Apoptosis is a frequent phenomenon in breast cancer and it can be detected by light microscopy in conventional histopathological sections or by special staining techniques. The number of apoptotic cells as a percentage of cells present, or the number of apoptotic cells per square millimetre of neoplastic tissue, is usually described as the apoptotic index (AI). In breast cancer, the AI is not related to tumour size, axillary lymph node metastasis or distant metastasis at diagnosis. It is greater in invasive ductal carcinomas than in other histological types. High AI is also related to high histological grade, high nuclear grade, comedo-type necrosis, lack of tubule formation, and dense infiltration of the tumour by lymphocytes. Sex steroid receptor-negative tumours have greater AIs than the sex steroid receptor-positive ones. Aneuploid breast cancers with high S-phase fractions (SPFs) also have high AI values compared with diploid tumours with low SPFs. p53-Positive breast cancers have high AIs, whereas tumours that are Bcl-2 positive have low AIs. The AI shows a strong positive correlation to all direct or indirect indicators of cell proliferation, such as mitotic index and Ki67 immunolabelling. Univariate survival analyses show that a high AI is linked with unfavourable disease outcome in axillary lymph node-negative and -positive breast cancer, but multivariate analyses indicate that AI is not an independent prognostic factor. In conclusion, a high AI is related to malignant cellular features and indicators of invasiveness and cell proliferation in breast cancer.

title: Role of tumor associated macrophages in tumor angiogenesis and lymphangiogenesis

text: Tumor angiogenesis is an essential process for supplying rapidly growing malignant tissues with essential nutrients and oxygen. An angiogenic switch allows tumor cells to survive and grow, and provides them access to vasculature resulting in metastatic disease. Monocyte-derived macrophages recruited and reprogrammed by tumor cells serve as a major source of angiogenic factors boosting the angiogenic switch. Tumor endothelium releases angiopoietin-2 and further facilitates recruitment of TIE2 receptor expressing monocytes (TEM) into tumor sites. Tumor-associated macrophages (TAM) sense hypoxia in avascular areas of tumors, and react by production of angiogenic factors such as VEGFA. VEGFA stimulates chemotaxis of endothelial cells (EC) and macrophages. In some tumors, TAM appeared to be a major source of MMP9. Elevated expression of MMP9 by TAM mediates extracellular matrix (ECM) degradation and the release of bioactive VEGFA. Other angiogenic factors released by TAM include basic fibroblast growth factor (bFGF), thymidine phosphorylase (TP), urokinase-type plasminogen activator (uPA), and adrenomedullin (ADM). The same factors used by macrophages for the induction of angiogenesis [like vascular endothelial growth factor A (VEGF-A) and MMP9] support lymphangiogenesis. TAM can express LYVE-1, one of the established markers of lymphatic endothelium. TAM support tumor lymphangiogenesis not only by secretion of pro-lymphangiogenic factors but also by trans-differentiation into lymphatic EC. New pro-angiogenic factor YKL-40 belongs to a family of mammalian chitinase-like proteins (CLP) that act as cytokines or growth factors. Human CLP family comprises YKL-40, YKL-39, and SI-CLP. Production of all three CLP in macrophages is antagonistically regulated by cytokines. It was recently established that YKL-40 induces angiogenesis in vitro and in animal tumor models. YKL-40-neutralizing monoclonal antibody blocks tumor angiogenesis and progression. The role of YKL-39 and SI-CLP in tumor angiogenesis and lymphangiogenesis remains to be investigated.

title: Stathmin overexpression identifies high-risk patients and lymph node metastasis in endometrial cancer.

text:
PURPOSE Overexpression of the oncogen Stathmin has been linked to aggressive endometrial carcinoma and a potential for PI3Kinase inhibitors in this disease. We wanted to validate the prognostic value of Stathmin expression in a large prospective multicenter setting. As lymph node sampling is part of current surgical staging, we also aimed to test if Stathmin expression in endometrial curettage specimens could predict lymph node metastasis.    EXPERIMENTAL DESIGN A total of 1,076 endometrial cancer patients have been recruited from 10 centers to investigate the biological tumor marker Stathmin in relation to clinicopathologic variables, including lymph node status and survival. Stathmin immunohistochemical staining was carried out in 477 hysterectomy and 818 curettage specimens.
 RESULTS Seventy-one percent of the patients (n = 763) were subjected to lymph node sampling, of which 12% had metastatic nodes (n = 94). Overexpression of Stathmin was detected in 37% (302 of 818) of the curettage and in 18% (84 of 477) of the hysterectomy specimens investigated. Stathmin overexpression in curettage and hysterectomy specimens were highly correlated and significantly associated with nonendometrioid histology, high grade, and aneuploidy. Stathmin analysis in preoperative curettage samples significantly correlated with, and was an independent predictor of, lymph node metastases. High Stathmin expression was associated with poor disease-specific survival (P ≤ 0.002) both in curettage and hysterectomy specimens.
 CONCLUSIONS Stathmin immunohistochemical staining identifies endometrial carcinomas with lymph node metastases and poor survival. The value, as a predictive marker for response to PI3Kinase inhibition and as a tool to stratify patients for lymph node sampling in endometrial carcinomas, remains to be determined.

title: Inflammatory T cells rapidly induce differentiation of human bone marrow stromal cells into mature osteoblasts.

text: Activated T cells secrete multiple osteoclastogenic cytokines which play a major role in the bone destruction associated with rheumatoid arthritis. While the role of T cells in osteoclastogenesis has received much attention recently, the effect of T cells on osteoblast formation and activity is poorly defined. In this study, we investigated the hypothesis that in chronic inflammation activated T cells contribute to enhanced bone turnover by promoting osteoblastic differentiation. We show that T cells produce soluble factors that induce alkaline phosphatase activity in bone marrow stromal cells and elevated expression of mRNA for Runx2 and osteocalcin. This data indicate that T cell derived factors have the capacity to stimulate the differentiation of bone marrow stromal cells into the osteoblast phenotype. RANKL mRNA was undetectable under any conditions in highly purified bone marrow stromal cells. In contrast, RANKL was constitutively expressed in primary osteoblasts and only moderately up-regulated by activated T cell conditioned medium. Interestingly, both bone marrow stromal cells and osteoblasts expressed mRNA for RANK, which was strongly up-regulated in both cell types by activated T cell conditioned medium. Although, mRNA for the RANKL decoy receptor, osteoprotegerin, was also up-regulated by activated T cell conditioned medium, it's inhibitory effects may be mitigated by a simultaneous rise in the osteoprotegerin competitor TNF-related apoptosis-inducing ligand. Based on our data we propose that during chronic inflammation, T cells regulate bone loss by a dual mechanism involving both direct stimulation of osteoclastogenesis, by production of osteoclastogenic cytokines, and indirectly by induction of osteoblast differentiation and up-regulation of bone turnover via coupling.

title: BMP/SMAD1 signaling sets a threshold for the left/right pathway in lateral plate mesoderm and limits availability of SMAD4.

text: Bistability in developmental pathways refers to the generation of binary outputs from graded or noisy inputs. Signaling thresholds are critical for bistability. Specification of the left/right (LR) axis in vertebrate embryos involves bistable expression of transforming growth factor beta (TGFbeta) member NODAL in the left lateral plate mesoderm (LPM) controlled by feed-forward and feedback loops. Here we provide evidence that bone morphogenetic protein (BMP)/SMAD1 signaling sets a repressive threshold in the LPM essential for the integrity of LR signaling. Conditional deletion of Smad1 in the LPM led to precocious and bilateral pathway activation. NODAL expression from both the left and right sides of the node contributed to bilateral activation, indicating sensitivity of mutant LPM to noisy input from the LR system. In vitro, BMP signaling inhibited NODAL pathway activation and formation of its downstream SMAD2/4-FOXH1 transcriptional complex. Activity was restored by overexpression of SMAD4 and in embryos, elevated SMAD4 in the right LPM robustly activated LR gene expression, an effect reversed by superactivated BMP signaling. We conclude that BMP/SMAD1 signaling sets a bilateral, repressive threshold for NODAL-dependent Nodal activation in LPM, limiting availability of SMAD4. This repressive threshold is essential for bistable output of the LR system.

title: The Dual Immunoregulatory function of Nlrp12 in T Cell-Mediated Immune Response: Lessons from Experimental Autoimmune Encephalomyelitis

text: Although the etiology of multiple sclerosis (MS) remains enigmatic, the role of T cells is unquestionably central in this pathology. Immune cells respond to pathogens and danger signals via pattern-recognition receptors (PRR). Several reports implicate Nlrp12, an intracellular PRR, in the development of a mouse MS-like disease, called Experimental Autoimmune Encephalomyelitis (EAE). In this study, we used induced and spontaneous models of EAE, as well as in vitro T cell assays, to test the hypothesis that Nlrp12 inhibits Th1 response and prevents T-cell mediated autoimmunity. We found that Nlrp12 plays a protective role in induced EAE by reducing IFNγ/IL-4 ratio in lymph nodes, whereas it potentiates the development of spontaneous EAE (spEAE) in 2D2 T cell receptor (TCR) transgenic mice. Looking into the mechanism of Nlrp12 activity in T cell response, we found that it inhibits T cell proliferation and suppresses Th1 response by reducing IFNγ and IL-2 production. Following TCR activation, Nlrp12 inhibits Akt and NF-κB phosphorylation, while it has no effect on S6 phosphorylation in the mTOR pathway. In conclusion, we propose a model that can explain the dual immunoregulatory function of Nlrp12 in EAE. We also propose a model explaining the molecular mechanism of Nlrp12-dependent regulation of T cell response.

title: Germinal Center T Follicular Helper Cells Are Highly Permissive to HIV-1 and Alter Their Phenotype during Virus Replication.

text: HIV-1 replication is concentrated within CD4(+) T cells in B cell follicles of secondary lymphoid tissues during asymptomatic disease. Limited data suggest that a subset of T follicular helper cells (TFH) within germinal centers (GC) is highly permissive to HIV-1. Whether GC TFH are the major HIV-1 virus-producing cells in vivo has not been established. In this study, we investigated TFH permissivity to HIV-1 ex vivo by spinoculating and culturing tonsil cells with HIV-1 GFP reporter viruses. Using flow cytometry, higher percentages of GC TFH (CXCR5(high)PD-1(high)) and CXCR5(+)programmed cell death-1 (PD-1)(low) cells were GFP(+) than non-GC TFH (CXCR5(+)PD-1(intermediate)) or extrafollicular (EF) (CXCR5(-)) cells. When sorted prior to spinoculation, however, GC TFH were substantially more permissive than CXCR5(+)PD-1(low) or EF cells, suggesting that many GC TFH transition to a CXCR5(+)PD-1(low) phenotype during productive infection. In situ hybridization on inguinal lymph node sections from untreated HIV-1-infected individuals without AIDS revealed higher frequencies of HIV-1 RNA(+) cells in GC than non-GC regions of follicle or EF regions. Superinfection of HIV-1-infected individuals' lymph node cells with GFP reporter virus confirmed the permissivity of follicular cells ex vivo. Lymph node immunostaining revealed 96% of CXCR5(+)CD4(+) cells were located in follicles. Within sorted lymph node cells from four HIV-infected individuals, CXCR5(+) subsets harbored 11-66-fold more HIV-1 RNA than CXCR5(-) subsets, as determined by RT PCR. Thus, GC TFH are highly permissive to HIV-1, but downregulate PD-1 and, to a lesser extent, CXCR5 during HIV-1 replication. These data further implicate GC TFH as the major HIV-1-producing cells in chronic asymptomatic HIV-1 infection.

title: Self-Organization of the Escherichia coli Chemotaxis Network Imaged with Super-Resolution Light Microscopy

text: The Escherichia coli chemotaxis network is a model system for biological signal processing. In E. coli, transmembrane receptors responsible for signal transduction assemble into large clusters containing several thousand proteins. These sensory clusters have been observed at cell poles and future division sites. Despite extensive study, it remains unclear how chemotaxis clusters form, what controls cluster size and density, and how the cellular location of clusters is robustly maintained in growing and dividing cells. Here, we use photoactivated localization microscopy (PALM) to map the cellular locations of three proteins central to bacterial chemotaxis (the Tar receptor, CheY, and CheW) with a precision of 15 nm. We find that cluster sizes are approximately exponentially distributed, with no characteristic cluster size. One-third of Tar receptors are part of smaller lateral clusters and not of the large polar clusters. Analysis of the relative cellular locations of 1.1 million individual proteins (from 326 cells) suggests that clusters form via stochastic self-assembly. The super-resolution PALM maps of E. coli receptors support the notion that stochastic self-assembly can create and maintain approximately periodic structures in biological membranes, without direct cytoskeletal involvement or active transport.

title: BASOPHILS AND THE T HELPER 2 ENVIRONMENT CAN PROMOTE THE DEVELOPMENT OF LUPUS NEPHRITIS

text: In systemic lupus erythematosus (SLE), self-reactive antibodies can target the kidney (lupus nephritis), leading to functional failure and possible mortality. We report that activation of basophils by autoreactive IgE causes their homing to lymph nodes, promoting T helper type 2 (T(H)2) cell differentiation and enhancing the production of self-reactive antibodies that cause lupus-like nephritis in mice lacking the Src family protein tyrosine kinase Lyn (Lyn(-/-) mice). Individuals with SLE also have elevated serum IgE, self-reactive IgEs and activated basophils that express CD62 ligand (CD62L) and the major histocompatibility complex (MHC) class II molecule human leukocyte antigen-DR (HLA-DR), parameters that are associated with increased disease activity and active lupus nephritis. Basophils were also present in the lymph nodes and spleen of subjects with SLE. Thus, in Lyn(-/-) mice, basophils and IgE autoantibodies amplify autoantibody production that leads to lupus nephritis, and in individuals with SLE IgE autoantibodies and activated basophils are factors associated with disease activity and nephritis.

title: Role of the Parasite-Derived Prostaglandin D2 in the Inhibition of Epidermal Langerhans Cell Migration during Schistosomiasis Infection

text: Epidermal Langerhans cells (LCs) play a key role in immune defense mechanisms and in numerous immunological disorders. In this report, we show that percutaneous infection of C57BL/6 mice with the helminth parasite Schistosoma mansoni leads to the activation of LCs but, surprisingly, to their retention in the epidermis. Moreover, using an experimental model of LC migration induced by tumor necrosis factor (TNF)-α, we show that parasites transiently impair the departure of LCs from the epidermis and their subsequent accumulation as dendritic cells in the draining lymph nodes. The inhibitory effect is mediated by soluble lipophilic factors released by the parasites and not by host-derived antiinflammatory cytokines, such as interleukin-10. We find that prostaglandin (PG)D2, but not the other major eicosanoids produced by the parasites, specifically impedes the TNF-α–triggered migration of LCs through the adenylate cyclase–coupled PGD2 receptor (DP receptor). Moreover, the potent DP receptor antagonist BW A868C restores LC migration in infected mice. Finally, in a model of contact allergen-induced LC migration, we show that activation of the DP receptor not only inhibits LC emigration but also dramatically reduces the contact hypersensitivity responses after challenge. Taken together, we propose that the inhibition of LC migration could represent an additional stratagem for the schistosomes to escape the host immune system and that PGD2 may play a key role in the control of cutaneous immune responses.

title: Subcapsular encounter and complement-dependent transport of immune complexes by lymph node B cells

text: The mechanism of B cell–antigen encounter in lymphoid tissues is incompletely understood. It is also unclear how immune complexes are transported to follicular dendritic cells. Here, using real-time two-photon microscopy we noted rapid delivery of immune complexes through the lymph to macrophages in the lymph node subcapsular sinus. B cells captured immune complexes by a complement receptor–dependent mechanism from macrophage processes that penetrated the follicle and transported the complexes to follicular dendritic cells. Furthermore, cognate B cells captured antigen-containing immune complexes from macrophage processes and migrated to the T zone. Our findings identify macrophages lining the subcapsular sinus as an important site of B cell encounter with immune complexes and show that intrafollicular B cell migration facilitates the transport of immune complexes as well as encounters with cognate antigen.


query: The deamination of cytidine to uridine on the minus strand of viral DNA can inactivate the viral genome by inducing G-to-A mutations.

title: Broad antiretroviral defence by human APOBEC3G through lethal editing of nascent reverse transcripts

text: Viral replication usually requires that innate intracellular lines of defence be overcome, a task usually accomplished by specialized viral gene products. The virion infectivity factor (Vif) protein of human immunodeficiency virus (HIV) is required during the late stages of viral production to counter the antiviral activity of APOBEC3G (apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G; also known as CEM15), a protein expressed notably in human T lymphocytes. When produced in the presence of APOBEC3G, vif-defective virus is non-infectious. APOBEC3G is closely related to APOBEC1, the central component of an RNA-editing complex that deaminates a cytosine residue in apoB messenger RNA. APOBEC family members also have potent DNA mutator activity through dC deamination; however, whether the editing potential of APOBEC3G has any relevance to HIV inhibition is unknown. Here, we demonstrate that it does, as APOBEC3G exerts its antiviral effect during reverse transcription to trigger G-to-A hypermutation in the nascent retroviral DNA. We also find that APOBEC3G can act on a broad range of retroviruses in addition to HIV, suggesting that hypermutation by editing is a general innate defence mechanism against this important group of pathogens.

title: The cytidine deaminase CEM15 induces hypermutation in newly synthesized HIV-1 DNA

text: High mutation frequency during reverse transcription has a principal role in the genetic variation of primate lentiviral populations. It is the main driving force for the generation of drug resistance and the escape from immune surveillance. G to A hypermutation is one of the characteristics of primate lentiviruses, as well as other retroviruses, during replication in vivo and in cell culture. The molecular mechanisms of this process, however, remain to be clarified. Here, we demonstrate that CEM15 (also known as apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like 3G; APOBEC3G), an endogenous inhibitor of human immunodeficiency virus type 1 (HIV-1) replication, is a cytidine deaminase and is able to induce G to A hypermutation in newly synthesized viral DNA. This effect can be counteracted by the HIV-1 virion infectivity factor (Vif). It seems that this viral DNA mutator is a viral defence mechanism in host cells that may induce either lethal hypermutation or instability of the incoming nascent viral reverse transcripts, which could account for the Vif-defective phenotype. Importantly, the accumulation of CEM15-mediated non-lethal hypermutation in the replicating viral genome could potently contribute to the genetic variation of primate lentiviral populations.

title: DNA Deamination Mediates Innate Immunity to Retroviral Infection

text: CEM15/APOBEC3G is a cellular protein required for resistance to infection by virion infectivity factor (Vif)-deficient human immunodeficiency virus (HIV). Here, using a murine leukemia virus (MLV)-based system, we provide evidence that CEM15/APOBEC3G is a DNA deaminase that is incorporated into virions during viral production and subsequently triggers massive deamination of deoxycytidine to deoxyuridine within the retroviral minus (first)-strand cDNA, thus providing a probable trigger for viral destruction. Furthermore, HIV Vif can protect MLV from this CEM15/APOBEC3G-dependent restriction. These findings imply that targeted DNA deamination is a major strategy of innate immunity to retroviruses and likely also contributes to the sequence variation observed in many viruses (including HIV).

title: Properties of Commelina yellow mottle virus's complete DNA sequence, genomic discontinuities and transcript suggest that it is a pararetrovirus.

text: The non-enveloped bacilliform viruses are the second group of plant viruses known to possess a genome consisting of circular double-stranded DNA. We have characterized the viral transcript and determined the complete sequence of the genome of Commelina mellow mottle virus (CoYMV), a member of this group. Analysis of the viral transcript indicates that the virus encodes a single terminally-redundant genome-length plus 120 nucleotide transcript. A fraction of the transcripts is polyadenylated, although the majority of the transcript is not polyadenylated. Analysis of the genome sequence indicates that the genome is 7489 bp in size and that the transcribed strand contains three open reading frames capable of encoding proteins of 23, 15 and 216 kd. The function of the 25 and 15 kd proteins is unknown. Similarities between the 216 kd polypeptide and the cauliflower mosaic virus coat protein and protease/reverse transcriptase polyprotein suggest that the 216 kd polypeptide is a polyprotein that is proteolytically processed to yield the virion coat protein, a protease, and replicase (reverse transcriptase and ribonuclease H). Each strand of the CoYMV genome is interrupted by site-specific discontinuities. The locations of the 5'-ends of these discontinuities, and the presence and location of a region on the CoYMV transcript capable of annealing with the 3'-end of cytosolic initiator methionine tRNA are consistent with replication by reverse transcription. We have demonstrated that a construct containing 1.3 CoYMV genomes is infective when introduced into Commelina diffusa, the host for CoYMV, using Agrobacterium-mediated infection.

title: RIG-I-mediated antiviral responses to single-stranded RNA bearing 5'-phosphates.

text: Double-stranded RNA (dsRNA) produced during viral replication is believed to be the critical trigger for activation of antiviral immunity mediated by the RNA helicase enzymes retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5). We showed that influenza A virus infection does not generate dsRNA and that RIG-I is activated by viral genomic single-stranded RNA (ssRNA) bearing 5'-phosphates. This is blocked by the influenza protein nonstructured protein 1 (NS1), which is found in a complex with RIG-I in infected cells. These results identify RIG-I as a ssRNA sensor and potential target of viral immune evasion and suggest that its ability to sense 5'-phosphorylated RNA evolved in the innate immune system as a means of discriminating between self and nonself.

title: EB virus-encoded RNAs are recognized by RIG-I and activate signaling to induce type I IFN.

text: Epstein-Barr virus (EBV)-encoded small RNAs (EBERs) are nonpolyadenylated, untranslated RNAs, exist most abundantly in latently EBV-infected cells, and are expected to show secondary structures with many short stem-loops. Retinoic acid-inducible gene I (RIG-I) is a cytosolic protein that detects viral double-stranded RNA (dsRNA) inside the cell and initiates signaling pathways leading to the induction of protective cellular genes, including type I interferons (IFNs). We investigated whether EBERs were recognized by RIG-I as dsRNA. Transfection of RIG-I plasmid induced IFNs and IFN-stimulated genes (ISGs) in EBV-positive Burkitt's lymphoma (BL) cells, but not in their EBV-negative counterparts or EBER-knockout EBV-infected BL cells. Transfection of EBER plasmid or in vitro-synthesized EBERs induced expression of type I IFNs and ISGs in RIG-I-expressing, EBV-negative BL cells, but not in RIG-I-minus counterparts. EBERs activated RIG-I's substrates, NF-kappaB and IFN regulatory factor 3, which were necessary for type I IFN activation. It was also shown that EBERs co-precipitated with RIG-I. These results indicate that EBERs are recognized by RIG-I and activate signaling to induce type I IFN in EBV-infected cells.

title: Engineered RNA viral synthesis of microRNAs.

text: MicroRNAs (miRNAs) are short noncoding RNAs that exert posttranscriptional gene silencing and regulate gene expression. In addition to the hundreds of conserved cellular miRNAs that have been identified, miRNAs of viral origin have been isolated and found to modulate both the viral life cycle and the cellular transcriptome. Thus far, detection of virus-derived miRNAs has been largely limited to DNA viruses, suggesting that RNA viruses may be unable to exploit this aspect of transcriptional regulation. Lack of RNA virus-produced miRNAs has been attributed to the replicative constraints that would incur following RNase III processing of a genomic hairpin. To ascertain whether the generation of viral miRNAs is limited to DNA viruses, we investigated whether influenza virus could be designed to deliver functional miRNAs without affecting replication. Here, we describe a modified influenza A virus that expresses cellular microRNA-124 (miR-124). Insertion of the miR-124 hairpin into an intron of the nuclear export protein transcript resulted in endogenous processing and functional miR-124. We demonstrate that a viral RNA genome incorporating a hairpin does not result in segment instability or miRNA-mediated genomic targeting, thereby permitting the virus to produce a miRNA without having a negative impact on viral replication. This work demonstrates that RNA viruses can produce functional miRNAs and suggests that this level of transcriptional regulation may extend beyond DNA viruses.

title: BCR/ABL oncogenic kinase promotes unfaithful repair of the reactive oxygen species-dependent DNA double-strand breaks.

text: The oncogenic BCR/ABL tyrosine kinase induces constitutive DNA damage in Philadelphia chromosome (Ph)-positive leukemia cells. We find that BCR/ABL-induced reactive oxygen species (ROSs) cause chronic oxidative DNA damage resulting in double-strand breaks (DSBs) in S and G(2)/M cell cycle phases. These lesions are repaired by BCR/ABL-stimulated homologous recombination repair (HRR) and nonhomologous end-joining (NHEJ) mechanisms. A high mutation rate is detected in HRR products in BCR/ABL-positive cells, but not in the normal counterparts. In addition, large deletions are found in NHEJ products exclusively in BCR/ABL cells. We propose that the following series of events may contribute to genomic instability of Ph-positive leukemias: BCR/ABL --> ROSs --> oxidative DNA damage --> DSBs in proliferating cells --> unfaithful HRR and NHEJ repair.

title: Helicobacter pylori infection triggers aberrant expression of activation-induced cytidine deaminase in gastric epithelium

text: Infection with Helicobacter pylori (H. pylori) is a risk factor for the development of gastric cancer. Here we show that infection of gastric epithelial cells with 'cag' pathogenicity island (cagPAI)-positive H. pylori induced aberrant expression of activation-induced cytidine deaminase (AID), a member of the cytidine-deaminase family that acts as a DNA- and RNA-editing enzyme, via the IκB kinase–dependent nuclear factor-κB activation pathway. H. pylori–mediated upregulation of AID resulted in the accumulation of nucleotide alterations in the TP53 tumor suppressor gene in gastric cells in vitro. Our findings provide evidence that aberrant AID expression caused by H. pylori infection might be a mechanism of mutation accumulation in the gastric mucosa during H. pylori–associated gastric carcinogenesis.

title: Rate and molecular spectrum of spontaneous mutations in the bacterium Escherichia coli as determined by whole-genome sequencing.

text: Knowledge of the rate and nature of spontaneous mutation is fundamental to understanding evolutionary and molecular processes. In this report, we analyze spontaneous mutations accumulated over thousands of generations by wild-type Escherichia coli and a derivative defective in mismatch repair (MMR), the primary pathway for correcting replication errors. The major conclusions are (i) the mutation rate of a wild-type E. coli strain is ~1 × 10(-3) per genome per generation; (ii) mutations in the wild-type strain have the expected mutational bias for G:C > A:T mutations, but the bias changes to A:T > G:C mutations in the absence of MMR; (iii) during replication, A:T > G:C transitions preferentially occur with A templating the lagging strand and T templating the leading strand, whereas G:C > A:T transitions preferentially occur with C templating the lagging strand and G templating the leading strand; (iv) there is a strong bias for transition mutations to occur at 5'ApC3'/3'TpG5' sites (where bases 5'A and 3'T are mutated) and, to a lesser extent, at 5'GpC3'/3'CpG5' sites (where bases 5'G and 3'C are mutated); (v) although the rate of small (≤4 nt) insertions and deletions is high at repeat sequences, these events occur at only 1/10th the genomic rate of base-pair substitutions. MMR activity is genetically regulated, and bacteria isolated from nature often lack MMR capacity, suggesting that modulation of MMR can be adaptive. Thus, comparing results from the wild-type and MMR-defective strains may lead to a deeper understanding of factors that determine mutation rates and spectra, how these factors may differ among organisms, and how they may be shaped by environmental conditions.

title: G-protein-coupled receptor of Kaposi's sarcoma-associated herpesvirus is a viral oncogene and angiogenesis activator.

text: The Kaposi's sarcoma-associated herpesvirus (KSHV/HHV8) is a gamma-2 herpesvirus that is implicated in the pathogenesis of Kaposi's sarcoma and of primary effusion B-cell lymphomas (PELs). KSHV infects malignant and progenitor cells of Kaposi's sarcoma and PEL, it encodes putative oncogenes and genes that may cause Kaposi's sarcoma pathogenesis by stimulating angiogenesis. The G-protein-coupled receptor encoded by an open reading frame (ORF 74) of KSHV is expressed in Kaposi's sarcoma lesions and in PEL and stimulates signalling pathways linked to cell proliferation in a constitutive (agonist-independent) way. Here we show that signalling by this KSHV G-protein-coupled receptor leads to cell transformation and tumorigenicity, and induces a switch to an angiogenic phenotype mediated by vascular endothelial growth factor, an angiogenesis and Kaposi's-spindle-cell growth factor. We find that this receptor can activate two protein kinases, JNK/SAPK and p38MAPK, by triggering signalling cascades like those induced by inflammatory cytokines that are angiogenesis activators and mitogens for Kaposi's sarcoma cells and B cells. We conclude that the KSHV G-protein-coupled receptor is a viral oncogene that can exploit cell signalling pathways to induce transformation and angiogenesis in KSHV-mediated oncogenesis.

title: Enterovirus-induced gene expression profile is critical for human pancreatic islet destruction

text: Virally induced inflammatory responses, beta cell destruction and release of beta cell autoantigens may lead to autoimmune reactions culminating in type 1 diabetes. Therefore, viral capability to induce beta cell death and the nature of virus-induced immune responses are among key determinants of diabetogenic viruses. We hypothesised that enterovirus infection induces a specific gene expression pattern that results in islet destruction and that such a host response pattern is not shared among all enterovirus infections but varies between virus strains. The changes in global gene expression and secreted cytokine profiles induced by lytic or benign enterovirus infections were studied in primary human pancreatic islet using DNA microarrays and viral strains either isolated at the clinical onset of type 1 diabetes or capable of causing a diabetes-like condition in mice. The expression of pro-inflammatory cytokine genes (IL-1-α, IL-1-β and TNF-α) that also mediate cytokine-induced beta cell dysfunction correlated with the lytic potential of a virus. Temporally increasing gene expression levels of double-stranded RNA recognition receptors, antiviral molecules, cytokines and chemokines were detected for all studied virus strains. Lytic coxsackievirus B5 (CBV-5)-DS infection also downregulated genes involved in glycolysis and insulin secretion. The results suggest a distinct, virus-strain-specific, gene expression pattern leading to pancreatic islet destruction and pro-inflammatory effects after enterovirus infection. However, neither viral replication nor cytotoxic cytokine production alone are sufficient to induce necrotic cell death. More likely the combined effect of these and possibly cellular energy depletion lie behind the enterovirus-induced necrosis of islets.

title: Porcine circovirus type 2 DNA influences cytoskeleton rearrangements in plasmacytoid and monocyte-derived dendritic cells.

text: Functional disruption of dendritic cells (DC) is an important strategy for viral pathogens to evade host defences. In this context, porcine circovirus type 2 (PCV2), a single-stranded DNA virus, impairs plasmacytoid DC (pDC) and conventional DC activation by certain viruses or Toll-like receptor (TLR) ligands. This inhibitory capacity is associated with the viral DNA, but the impairment does not affect all signalling cascades; TLR7 ligation by small chemical molecules will still induce interleukin-6 (IL-6) and tumour necrosis factor-α secretion, but not interferon-α or IL-12. In this study, the molecular mechanisms by which silencing occurs were investigated. PP2, a potent inhibitor of the Lyn and Hck kinases, produced a similar profile to the PCV2 DNA interference with cytokine secretion by pDC, efficiently inhibiting cell activation induced through TLR9, but not TLR7, ligation. Confocal microscopy and cytometry analysis strongly suggested that PCV2 DNA impairs actin polymerization and endocytosis in pDC and monocyte-derived DC, respectively. Altogether, this study delineates for the first time particular molecular mechanisms involved in PCV2 interference with DC danger recognition, which may be responsible for the virus-induced immunosuppression observed in infected pigs.

title: Summary

text: The genetic diseases Hutchinson-Gilford progeria syndrome (HGPS) and restrictive dermopathy (RD) arise from accumulation of farnesylated prelamin A because of defects in the lamin A maturation pathway. Both of these diseases exhibit symptoms that can be viewed as accelerated aging. The mechanism by which accumulation of farnesylated prelamin A leads to these accelerated aging phenotypes is not understood. Here we present evidence that in HGPS and RD fibroblasts, DNA damage checkpoints are persistently activated because of the compromise in genomic integrity. Inactivation of checkpoint kinases Ataxia-telangiectasia-mutated (ATM) and ATR (ATM- and Rad3-related) in these patient cells can partially overcome their early replication arrest. Treatment of patient cells with a protein farnesyltransferase inhibitor (FTI) did not result in reduction of DNA double-strand breaks and damage checkpoint signaling, although the treatment significantly reversed the aberrant shape of their nuclei. This suggests that DNA damage accumulation and aberrant nuclear morphology are independent phenotypes arising from prelamin A accumulation in these progeroid syndromes. Since DNA damage accumulation is an important contributor to the symptoms of HGPS, our results call into question the possibility of treatment of HGPS with FTIs alone.

title: The DNA polymerase λ is required for the repair of non-compatible DNA double strand breaks by NHEJ in mammalian cells

text: DNA polymerase lambda (polλ) is a recently identified DNA polymerase whose cellular function remains elusive. Here we show, that polλ participates at the molecular level in a chromosomal context, in the repair of DNA double strand breaks (DSB) via non-homologous end joining (NHEJ) in mammalian cells. The expression of a catalytically inactive form of polλ (polλDN) decreases the frequency of NHEJ events in response to I-Sce-I-induced DSB whereas inactivated forms of its homologues polβ and polμ do not. Only events requiring DNA end processing before ligation are affected; this defect is associated with large deletions arising in the vicinity of the induced DSB. Furthermore, polλDN-expressing cells exhibit increased sensitization and genomic instability in response to ionizing radiation similar to that of NHEJ-defective cells. Our data support a requirement for polλ in repairing a subset of DSB in genomic DNA, thereby contributing to the maintenance of genetic stability mediated by the NHEJ pathway.

title: Herpesvirus-encoded GPCRs: neglected players in inflammatory and proliferative diseases?

text: Herpesviruses encode membrane-associated G protein-coupled receptors (GPCRs) in their viral genomes that are structurally similar to chemokine receptors. These GPCRs hijack GPCR-mediated cellular signalling networks of the host for survival, replication and pathogenesis. In particular the herpesvirus-encoded chemokine receptors ORF74, BILF1 and US28, which are present at inflammatory sites and tumour cells, provide important virus-specific targets for directed therapies. Given the high druggability of GPCRs in general, these viral GPCRs can be considered promising antiviral drug targets.

title: The BRRF1 early gene of Epstein-Barr virus encodes a transcription factor that enhances induction of lytic infection by BRLF1.

text: The switch from the latent to the lytic form of Epstein-Barr virus (EBV) infection is mediated by expression of the viral immediate-early (IE) proteins, BZLF1 (Z) and BRLF1 (R). An EBV early protein, BRRF1 (Na), is encoded by the opposite strand of the BRLF1 intron, but the function of this nuclear protein in the viral life cycle is unknown. Here we demonstrate that Na enhances the R-mediated induction of lytic EBV infection in 293 cells latently infected with a recombinant EBV (R-KO) defective for the expression of both R and Na. Na also enhances R-induced lytic infections in a gastric carcinoma line (AGS) carrying the R-KO virus, although it has no effect in a Burkitt lymphoma line (BL-30) stably infected with the same mutant virus. We show that Na is a transcription factor that increases the ability of R to activate Z expression from the R-KO viral genome in 293 cells and that Na by itself activates the Z promoter (Zp) in EBV-negative cells. Na activation of Zp requires a CRE motif (ZII), and a consensus CRE motif is sufficient to transfer Na responsiveness to the heterologous E1b promoter. Furthermore, we show that Na enhances the transactivator function of a Gal4-c-Jun fusion protein but does not increase the transactivator function of other transcription factors (including ATF-1, ATF-2, and CREB) known to bind CRE motifs. Na expression in cells results in increased levels of a hyperphosphorylated form of c-Jun, suggesting a mechanism by which Na activates c-Jun. Our results indicate that Na is a transcription factor that activates the EBV Zp IE promoter through its effects on c-Jun and suggest that Na cooperates with BRLF1 to induce the lytic form of EBV infection in certain cell types.

title: Cytosolic viral sensor RIG-I is a 5'-triphosphate-dependent translocase on double-stranded RNA.

text: Retinoic acid inducible-gene I (RIG-I) is a cytosolic multidomain protein that detects viral RNA and elicits an antiviral immune response. Two N-terminal caspase activation and recruitment domains (CARDs) transmit the signal, and the regulatory domain prevents signaling in the absence of viral RNA. 5'-triphosphate and double-stranded RNA (dsRNA) are two molecular patterns that enable RIG-I to discriminate pathogenic from self-RNA. However, the function of the DExH box helicase domain that is also required for activity is less clear. Using single-molecule protein-induced fluorescence enhancement, we discovered a robust adenosine 5'-triphosphate-powered dsRNA translocation activity of RIG-I. The CARDs dramatically suppress translocation in the absence of 5'-triphosphate, and the activation by 5'-triphosphate triggers RIG-I to translocate preferentially on dsRNA in cis. This functional integration of two RNA molecular patterns may provide a means to specifically sense and counteract replicating viruses.

title: Recruitment of Tat to heterochromatin protein HP1 via interaction with CTIP2 inhibits human immunodeficiency virus type 1 replication in microglial cells.

text: The Tat protein of human immunodeficiency virus type 1 (HIV-1) plays a key role as inducer of viral gene expression. We report that Tat function can be potently inhibited in human microglial cells by the recently described nuclear receptor cofactor chicken ovalbumin upstream promoter transcription factor-interacting protein 2 (CTIP2). Overexpression of CTIP2 leads to repression of HIV-1 replication, as a result of inhibition of Tat-mediated transactivation. In contrast, the related CTIP1 was unable to affect Tat function and viral replication. Using confocal microscopy to visualize Tat subcellular distribution in the presence of the CTIPs, we found that overexpression of CTIP2, and not of CTIP1, leads to disruption of Tat nuclear localization and recruitment of Tat within CTIP2-induced nuclear ball-like structures. In addition, our studies demonstrate that CTIP2 colocalizes and associates with the heterochromatin-associated protein HP1alpha. The CTIP2 protein harbors two Tat and HP1 interaction interfaces, the 145-434 and the 717-813 domains. CTIP2 and HP1alpha associate with Tat to form a three-protein complex in which the 145-434 CTIP2 domain interacts with the N-terminal region of Tat, while the 717-813 domain binds to HP1. The importance of this Tat binding interface and of Tat subnuclear relocation was confirmed by analysis of CTIP2 deletion mutants. Our findings suggest that inhibition of HIV-1 expression by CTIP2 correlates with recruitment of Tat within CTIP2-induced structures and relocalization within inactive regions of the chromatin via formation of the Tat-CTIP2-HP1alpha complex. These data highlight a new mechanism of Tat inactivation through subnuclear relocalization that may ultimately lead to inhibition of viral pathogenesis.

title: Nucleotide sequence of an avian sarcoma virus oncogene (src) and proposed amino acid sequence for gene product

text: The transforming gene (src) of avian sarcoma virus (ASV) and adjacent regions of the viral genome have been isolated by molecular cloning of viral DNA. Their nucleotide sequence encompasses the whole of src and the portion of the gene env that encodes gp 37, one of two glycoproteins found in the viral envelope. Src encodes a single, hydrophobic protein with structural features that conform to previous descriptions of the gene product (pp60src). It appears that a single viral protein is responsible for both the initiation and maintenance of neoplastic transformation by avian sarcoma virus. Neither src nor its product bear any obvious structural relationship to several other viral oncogenes and their encoded proteins. Src is flanked by a repeated nucleotide sequence that may facilitate frequent deletion of the gene from the viral genome.


query: The density of cytokine receptor bearing cells affects the distance over which cytokines act.

title: A Tunable Diffusion‐Consumption Mechanism of Cytokine Propagation Enables Plasticity in Cell‐to‐Cell Communication in the Immune System

text: &NA; Immune cells communicate by exchanging cytokines to achieve a context‐appropriate response, but the distances over which such communication happens are not known. Here, we used theoretical considerations and experimental models of immune responses in vitro and in vivo to quantify the spatial extent of cytokine communications in dense tissues. We established that competition between cytokine diffusion and consumption generated spatial niches of high cytokine concentrations with sharp boundaries. The size of these self‐assembled niches scaled with the density of cytokine‐consuming cells, a parameter that gets tuned during immune responses. In vivo, we measured interactions on length scales of 80–120 &mgr;m, which resulted in a high degree of cell‐to‐cell variance in cytokine exposure. Such heterogeneous distributions of cytokines were a source of non‐genetic cell‐to‐cell variability that is often overlooked in single‐cell studies. Our findings thus provide a basis for understanding variability in the patterning of immune responses by diffusible factors. Graphical Abstract Figure. No caption available. HighlightsCytokine penetration in tissues is governed by a diffusion‐consumption mechanismSpherical cytokine niches are generated around cytokine‐producing cellsThe characteristic niche size depends on the density of cytokine consumersCytokine niches are a source of variability in otherwise identical cells &NA; Cytokine‐mediated communication allows immune cells to achieve a context‐appropriate response, but the distance over which this communication happens is unclear. Oyler‐Yaniv et al. (2017) show that a simple diffusion‐consumption mechanism quantitatively describes the spatial spread of cytokines in vivo and results in localized niches of high cytokine concentrations that contribute to cell‐to‐cell variability.

title: Cytokine control of memory T-cell development and survival

text: Evidence has accumulated that cytokines have a fundamental role in the differentiation of memory T cells. Here, we follow the CD8+ T cell from initial activation to memory-cell generation, indicating the checkpoints at which cytokines determine the fate of the T cell. Members of the common cytokine-receptor γ-chain (γc)-cytokine family — in particular, interleukin-7 (IL-7) and IL-15 — act at each stage of the immune response to promote proliferation and survival. In this manner, a stable and protective, long-lived memory CD8+ T-cell pool can be propagated and maintained.

title: Induction of myelodysplasia by myeloid-derived suppressor cells.

text: Myelodysplastic syndromes (MDS) are age-dependent stem cell malignancies that share biological features of activated adaptive immune response and ineffective hematopoiesis. Here we report that myeloid-derived suppressor cells (MDSC), which are classically linked to immunosuppression, inflammation, and cancer, were markedly expanded in the bone marrow of MDS patients and played a pathogenetic role in the development of ineffective hematopoiesis. These clonally distinct MDSC overproduce hematopoietic suppressive cytokines and function as potent apoptotic effectors targeting autologous hematopoietic progenitors. Using multiple transfected cell models, we found that MDSC expansion is driven by the interaction of the proinflammatory molecule S100A9 with CD33. These 2 proteins formed a functional ligand/receptor pair that recruited components to CD33’s immunoreceptor tyrosine-based inhibition motif (ITIM), inducing secretion of the suppressive cytokines IL-10 and TGF-β by immature myeloid cells. S100A9 transgenic mice displayed bone marrow accumulation of MDSC accompanied by development of progressive multilineage cytopenias and cytological dysplasia. Importantly, early forced maturation of MDSC by either all-trans-retinoic acid treatment or active immunoreceptor tyrosine-based activation motif–bearing (ITAM-bearing) adapter protein (DAP12) interruption of CD33 signaling rescued the hematologic phenotype. These findings indicate that primary bone marrow expansion of MDSC driven by the S100A9/CD33 pathway perturbs hematopoiesis and contributes to the development of MDS.

title: Keeping your senescent cells under control

text: Cellular senescence is a stable form of cell-cycle arrest which is thought to limit the proliferative potential of premalignant cells [1]. The senescence phenotype was initially described by Hayflick and Moorhead in 1961 on human fibroblasts undergoing replicative exhaustion in culture [2]. It has been shown that senescence can be triggered in different cell types in response to diverse forms of cellular damage or stress (for review see [1]). Importantly, while senescence was denounced as a tissue culture phenomenon for many years, recent in vivo studies demonstrated that cellular senescence represents a potent failsafe mechanism against tumorigenesis and contributes to the cytotoxicity of certain anticancer agents (see for example [3-7]). Interestingly, senescent cells have also been observed in certain aged or damaged tissues and there is growing evidence that senescence checkpoints can affect the regenerative reserve of tissues and organismal aging [8-11]. However, senescence may also have positive effects on organ maintenance by limiting pathological responses to acute forms of injury such as fibrotic scarring in response to chemical induced liver injury [12].     Over the past years it was also shown that senescent cells can communicate with their environment by secreting a myriad of cytokines and growth factors. Interestingly, this "senescence associated secretory phenotype (SASP)" seems to be a double edged sword regarding tumor initiation and maintenance:    i)    On the one hand, it has been shown that the SASP can have pro-tumorigenic effects. In an experimental system it was shown that senescent mesenchymal cells can enhance the tumorigenicity of surrounding breast cancer cells [13].     ii)    Similarly, it is possible that the SASP enhances selection of transformed cell clones in aged organ systems. It has been shown that loss of proliferative competition of non-transformed cells can accelerate leukemogenesis [14]. It remains to be seen whether aberrant secretion of cytokines and growth factors by the SASP can accelerated this process in aged and chronically damage organ systems.     iii)    In contrast to its pro-tumorigenic aspect, the SASP could also have anti-tumor effects. A recent study showed that in a mosaic liver cancer mouse model the activation of p53 induced senescence, an upregulation of inflammatory cytokines, and activation of innate immune responses leading to tumour cell clearance [15].     iv)    In further support that the SASP could have anti-tumor activities, a series of recent papers showed that components of the SASP can stabilize the senescence cell cycle arrest via an autoregulatory feedback loop [16,17] or induces apoptosis of tumor cells [18].     In addition to its effects on tumorigenesis, the SASP could also influence tissue aging. Studies on aging telomere dysfunctional mice have provided direct experimental evidence for an in vivo activation of the SASP in response to telomere dysfunction [19]. Interestingly, this in vivo SASP provoked alterations in stem cell differentiation (skewing of hematopoiesis towards reduction in lymphopoiesis and enhancement of myelopoiesis) that are also characteristic signs of human aging.         Figure 1.     Different cellular stresses can induce senescence including telomere shortening, DNA damage, and oncogene activation. Senescence of tumor cells ...         In light of the many possible roles o the SASP in aging and carcinogenesis, it appears to be of utmost importance to decipher regulatory pathways controlling the SASP. In a current publication, Bhaumik et al. have identified 2 microRNAs (miR-146a/b) that negatively regulate the secretion of IL-6 and IL-8 - two of the SASP [20]. The authors show that these microRNAs are up-regulated at late stages of senescence, many days after a permanent cell cycle arrest has been established. Interestingly, the inhibitory miRs are most strongly up-regulated in senescence of cell lines that show a strong SASP but not in cell lines characterized by a weak SASP. The authors propose a new concept indicating that miRs 146a and b function in a negative feedback loop preventing an over-activation of the SASP in senescent cells. The authors present some initial data suggesting that activation of this negative feedback loop involves IL-1 receptor, IRAK-1, and NFκB signalling leading to an up-regulation of miRs-146a and b. A direct proof that this proposed feedback loop suppresses over-activation of the SASP remains to be demonstrated in future studies. The authors show that blockage of IL-1-receptor signalling prevents both the up-regulation of miRs-146a and b as well as Il-6 secretion. To confirm their new concept, it would be important to show that a selective blockage of miRs-146a and b results in over-activation of the SASP.     The work by Bhaumik et al. places mir-146a/b as central players to control IL-6 and IL-8 expression within the SASP. MicroRNAs are emerging therapeutic targets because their expression levels can be effectively modulated via the use of antagomirs (see for example [21]). Also, for increasing microRNA expression, microRNAs can be delivered into cellsin vivo (see for example [22]). Therefore, it will be interesting to functionally test the impact of mir-146 inhibition on tumorigenesis and aging in relevant mouse models. Such studies will be of particular interest, as recent work showed that IL-6 secretion by senescent cells is relevant for initiating and maintaining the senescene response via an autocrine loop [17]. A reduction of miR-146 could increase IL-6 levels in senescent cells, which should stabilize the senescence program and reduce the risk of malignant transformation. Furthermore, it can be speculated that reduction of mir-146 a/b will increase NfκB activation via IRAK1. As NfκB is modulating the expression of various inflammation associated genes, this may also lead to increased clearance of senescent tumor cells by the innate immune system. However, it should be mentioned that Il-6 secreted by senescent cells can also act as a mitogen for surrounding cells, thus potentially increasing the risk of malignant transformation [13,17]. Besides its function in SASP modulation, miR-146 was also reported to target the mRNAs of the BRCA1 and BRCA2 tumor suppressors. In a recent study a G to C polymorphism in miR-146, which leads to an increased processing and release of the mature microRNA, can predict an early onset of breast cancer [23].     Taken together, the study of Bhaumik et al. opens an interesting new research area dealing with the gene regulatory mechanisms that control activation of the SASP. Given the diverse roles of the SASP in modulating tumor progression, immune surveillance of damaged cells, and the stabilization of the senescence arrest itself, it will be of great interest to analyse the influence of SASP regulatory pathways during aging and cancer.

title: Estrogen receptor-alpha promotes alternative macrophage activation during cutaneous repair.

text: Efficient local monocyte/macrophage recruitment is critical for tissue repair. Recruited macrophages are polarized toward classical (proinflammatory) or alternative (prohealing) activation in response to cytokines, with tight temporal regulation crucial for efficient wound repair. Estrogen acts as a potent anti-inflammatory regulator of cutaneous healing. However, an understanding of estrogen/estrogen receptor (ER) contribution to macrophage polarization and subsequent local effects on wound healing is lacking. Here we identify, to our knowledge previously unreported, a role whereby estrogen receptor α (ERα) signaling preferentially polarizes macrophages from a range of sources to an alternative phenotype. Cell-specific ER ablation studies confirm an in vivo role for inflammatory cell ERα, but not ERβ, in poor healing associated with an altered cytokine profile and fewer alternatively activated macrophages. Furthermore, we reveal intrinsic changes in ERα-deficient macrophages, which are unable to respond to alternative activation signals in vitro. Collectively, our data reveal that inflammatory cell-expressed ERα promotes alternative macrophage polarization, which is beneficial for timely healing. Given the diverse physiological roles of ERs, these findings will likely be of relevance to many pathologies involving excessive inflammation.

title: Interleukin 18 function in atherosclerosis is mediated by the interleukin 18 receptor and the Na-Cl co-transporter

text: Interleukin-18 (IL18) participates in atherogenesis through several putative mechanisms. Interruption of IL18 action reduces atherosclerosis in mice. Here, we show that absence of the IL18 receptor (IL18r) does not affect atherosclerosis in apolipoprotein E–deficient (Apoe−/−) mice, nor does it affect IL18 cell surface binding to or signaling in endothelial cells. As identified initially by co-immunoprecipitation with IL18, we found that IL18 interacts with the Na-Cl co-transporter (NCC; also known as SLC12A3), a 12-transmembrane-domain ion transporter protein preferentially expressed in the kidney. NCC is expressed in atherosclerotic lesions, where it colocalizes with IL18r. In Apoe−/− mice, combined deficiency of IL18r and NCC, but not single deficiency of either protein, protects mice from atherosclerosis. Peritoneal macrophages from Apoe−/− mice or from Apoe−/− mice lacking IL18r or NCC show IL18 binding and induction of cell signaling and cytokine and chemokine expression, but macrophages from Apoe−/− mice with combined deficiency of IL18r and NCC have a blunted response. An interaction between NCC and IL18r on macrophages was detected by co-immunoprecipitation. IL18 binds to the cell surface of NCC-transfected COS-7 cells, which do not express IL18r, and induces cell signaling and cytokine expression. This study identifies NCC as an IL18-binding protein that collaborates with IL18r in cell signaling, inflammatory molecule expression, and experimental atherogenesis.

title: Gr-1+CD11b+ myeloid cells tip the balance of immune protection to tumor promotion in the premetastatic lung.

text: The mechanisms by which a primary tumor affects a selected distant organ before tumor cell arrival remain to be elucidated. This report shows that Gr-1+CD11b+ cells are significantly increased in lungs of mice bearing mammary adenocarcinomas before tumor cell arrival. In the premetastatic lungs, these immature myeloid cells significantly decrease IFN-gamma production and increase proinflammatory cytokines. In addition, they produce large quantities of matrix metalloproteinase 9 (MMP9) and promote vascular remodeling. Deletion of MMP9 normalizes aberrant vasculature in the premetastatic lung and diminishes lung metastasis. The production and activity of MMP9 is selectively restricted to lungs and organs with a large number of Gr-1+CD11b+ cells. Our work reveals a novel protumor mechanism for Gr-1+CD11b+ cells that changes the premetastatic lung into an inflammatory and proliferative environment, diminishes immune protection, and promotes metastasis through aberrant vasculature formation. Thus, inhibition of Gr-1+CD11b+ cells could normalize the premetastatic lung environment, improve host immunosurveillance, and inhibit tumor metastasis.

title: Current knowledge and future directions of TLR and NOD signaling in sepsis

text: The incidence of sepsis is increasing over time, along with an increased risk of dying from the condition. Sepsis care costs billions annually in the United States. Death from sepsis is understood to be a complex process, driven by a lack of normal immune homeostatic functions and excessive production of proinflammatory cytokines, which leads to multi-organ failure. The Toll-like receptor (TLR) family, one of whose members was initially discovered in Drosophila, performs an important role in the recognition of microbial pathogens. These pattern recognition receptors (PRRs), upon sensing invading microorganisms, activate intracellular signal transduction pathways. NOD signaling is also involved in the recognition of bacteria and acts synergistically with the TLR family in initiating an efficient immune response for the eradication of invading microbial pathogens. TLRs and NOD1/NOD2 respond to different pathogen-associated molecular patterns (PAMPs). Modulation of both TLR and NOD signaling is an area of research that has prompted much excitement and debate as a therapeutic strategy in the management of sepsis. Molecules targeting TLR and NOD signaling pathways exist but regrettably thus far none have proven efficacy from clinical trials.

title: Neuroinflammation in spinal cord injury: therapeutic targets for neuroprotection and regeneration.

text: Traumatic spinal cord injury triggers a complex local inflammatory reaction capable of enhancing repair and exacerbating pathology. The composition and effector potential of the post-injury cellular and molecular immune cascade changes as a function of time and distance from the lesion. Production along this time-space continuum of cytokines, proteases, and growth factors establishes dynamic environments that lead to the death, damage, repair or growth of affected neurons and glia. Microenvironmental cues, therefore, generated by the cells therein, may determine these distinct fates of repair versus pathology. To harness repair, it is necessary to manipulate the assembly and phenotype of cells that comprise the neuroinflammatory response to injury. Here, the potential of the neuroinflammatory response to cause outcomes such as pain, regeneration, and functional recovery is reviewed.

title: Involvement of transient receptor potential vanilloid 1 receptors in protease-activated receptor-2-induced joint inflammation and nociception.

text: Protease-activated receptor-2 (PAR-2) is a G-protein-coupled receptor activated through proteolytic cleavage. It is localized on epithelial, endothelial and inflammatory cells, as well as on transient receptor potential vanilloid 1 (TRPV1) receptor-expressing neurones. It plays an important role in inflammatory/nociceptive processes. Since there are few reports concerning PAR-2 function in joints, the effects of intraarticular PAR-2 activation on joint pain and inflammation were studied. Secondary hyperalgesia/allodynia, spontaneous weight distribution, swelling and inflammatory cytokine production were measured and the involvement of TRPV1 ion channels was investigated in rats and mice. Injection of the PAR-2 receptor agonist SLIGRL-NH(2) into the knee decreased touch sensitivity and weight bearing of the ipsilateral hindlimb in both species. Secondary mechanical allodynia/hyperalgesia and impaired weight distribution were significantly reduced by the TRPV1 antagonist SB366791 in rats and by the genetic deletion of this receptor in mice. PAR-2 activation did not cause significant joint swelling, but increased IL-1beta concentration which was not influenced by the lack of the TRPV1 channel. For comparison, intraplantar SLIGRL-NH(2) evoked similar primary mechanical hyperalgesia and impaired weight distribution in both WT and TRPV1 deficient mice, but oedema was smaller in the knockouts. The inactive peptide, LRGILS-NH(2), injected into either site did not induce any inflammatory or nociceptive changes. These data provide evidence for a significant role of TRPV1 receptors in secondary mechanical hyperalgesia/allodynia and spontaneous pain induced by PAR-2 receptor activation in the knee joint. Although intraplantar PAR-2 activation-induced oedema is also TRPV1 receptor-mediated, primary mechanical hyperalgesia, impaired weight distribution and IL-1beta production are independent of this channel.

title: High-Density Lipoproteins Exert Pro-inflammatory Effects on Macrophages via Passive Cholesterol Depletion and PKC-NF-κB/STAT1-IRF1 Signaling.

text: Membrane cholesterol modulates a variety of cell signaling pathways and functions. While cholesterol depletion by high-density lipoproteins (HDLs) has potent anti-inflammatory effects in various cell types, its effects on inflammatory responses in macrophages remain elusive. Here we show overt pro-inflammatory effects of HDL-mediated passive cholesterol depletion and lipid raft disruption in murine and human primary macrophages in vitro. These pro-inflammatory effects were confirmed in vivo in peritoneal macrophages from apoA-I transgenic mice, which have elevated HDL levels. In line with these findings, the innate immune responses required for clearance of P. aeruginosa bacterial infection in lung were compromised in mice with low HDL levels. Expression analysis, ChIP-PCR, and combinatorial pharmacological and genetic intervention studies unveiled that both native and reconstituted HDL enhance Toll-like-receptor-induced signaling by activating a PKC-NF-κB/STAT1-IRF1 axis, leading to increased inflammatory cytokine expression. HDL's pro-inflammatory activity supports proper functioning of macrophage immune responses.

title: The precursor form of IL-1alpha is an intracrine proinflammatory activator of transcription.

text: Although most cytokines are studied for biological effects after engagement of their specific cell surface membrane receptors, increasing evidence suggests that some function in the nucleus. In the present study, the precursor form of IL-1alpha was overexpressed in various cells and assessed for activity in the presence of saturating concentrations of IL-1 receptor antagonist to prevent receptor signaling. Initially diffusely present in the cytoplasm of resting cells, IL-1alpha translocated to the to nucleus after activation by endotoxin, a Toll-like receptor ligand. The IL-1alpha precursor, but not the C-terminal mature form, activated the transcriptional machinery in the GAL4 system by 90-fold; a 50-fold increase was observed using only the IL-1alpha propiece, suggesting that transcriptional activation was localized to the N terminus where the nuclear localization sequence resides. Under conditions of IL-1 receptor blockade, intracellular overexpression of the precursor and propiece forms of IL-1alpha were sufficient to activate NF-kappaB and AP-1. Stable transfectants overproducing precursor IL-1alpha released the cytokines IL-8 and IL-6 but also exhibited a significantly lower threshold of activation to subpicomolar concentrations of tumor necrosis factor alpha or IFN-gamma. Thus, intracellular functions of IL-1alpha might play an unforeseen role in the genesis of inflammation. During disease-driven events, the cytosolic precursor moves to the nucleus, where it augments transcription of proinflammatory genes. Because this mechanism of action is not affected by extracellular inhibitors, reducing intracellular functions of IL-1alpha might prove beneficial in some inflammatory conditions.

title: T helper 2 cytokines inhibit autophagic control of intracellular Mycobacterium tuberculosis.

text: Autophagy is a recently recognized immune effector mechanism against intracellular pathogens. The role of autophagy in innate immunity has been well established, but the extent of its regulation by the adaptive immune response is less well understood. The T helper 1 (Th1) cell cytokine IFN-gamma induces autophagy in macrophages to eliminate Mycobacterium tuberculosis. Here, we report that Th2 cytokines affect autophagy in macrophages and their ability to control intracellular M. tuberculosis. IL-4 and IL-13 abrogated autophagy and autophagy-mediated killing of intracellular mycobacteria in murine and human macrophages. Inhibition of starvation-induced autophagy by IL-4 and IL-13 was dependent on Akt signaling, whereas the inhibition of IFN-gamma-induced autophagy was Akt independent and signal transducer and activator of transcription 6 (STAT6) dependent. These findings establish a mechanism through which Th1-Th2 polarization differentially affects the immune control of intracellular pathogens.

title: Inter-individual variability and genetic influences on cytokine responses to bacteria and fungi

text: Little is known about the inter-individual variation of cytokine responses to different pathogens in healthy individuals. To systematically describe cytokine responses elicited by distinct pathogens and to determine the effect of genetic variation on cytokine production, we profiled cytokines produced by peripheral blood mononuclear cells from 197 individuals of European origin from the 200 Functional Genomics (200FG) cohort in the Human Functional Genomics Project (http://www.humanfunctionalgenomics.org), obtained over three different years. We compared bacteria- and fungi-induced cytokine profiles and found that most cytokine responses were organized around a physiological response to specific pathogens, rather than around a particular immune pathway or cytokine. We then correlated genome-wide single-nucleotide polymorphism (SNP) genotypes with cytokine abundance and identified six cytokine quantitative trait loci (QTLs). Among them, a cytokine QTL at the NAA35-GOLM1 locus markedly modulated interleukin (IL)-6 production in response to multiple pathogens and was associated with susceptibility to candidemia. Furthermore, the cytokine QTLs that we identified were enriched among SNPs previously associated with infectious diseases and heart diseases. These data reveal and begin to explain the variability in cytokine production by human immune cells in response to pathogens.

title: Coordinate regulation of the IL-4, IL-13, and IL-5 cytokine cluster in Th2 clones revealed by allelic expression patterns.

text: The cytokines IL-4, IL-13, and IL-5 are markers for the Th2 subset of effector T cells and are often expressed together. These cytokine genes are organized within 140 kb of orthologous DNA in both mouse and human. Using IL-4-expressing CD4+ T cell clones derived from F1 mice, we identified allelic polymorphisms for each of these cytokines and assessed the parental identity of the cytokine mRNAs. Both monoallelic and biallelic expression occurred for each gene and for an additional gene, IL-3, that lies with GM-CSF over 450 kb telomeric on the same chromosome. When coexpressed in T cell clones, IL-4 was expressed from the same allele as IL-13 or IL-5 in 81% of instances. In contrast, there was only 52% concordance of these three cytokines at the allelic level among clones that expressed IL-3. Independent expression of the cytokine alleles occurs commonly in T cells, but the clustered locus encompassing IL-4, IL-13, and IL-5 is subject to coordinate regulation.

title: Lipopolysaccharide-dependent prostaglandin E(2) production is regulated by the glutathione-dependent prostaglandin E(2) synthase gene induced by the Toll-like receptor 4/MyD88/NF-IL6 pathway.

text: Macrophages produce a large amount of PGE(2) during inflammation. This lipid mediator modulates various immune responses. PGE(2) acts on macrophages and inhibits production of cytokines such as TNF-alpha and IL-12. Membrane-bound glutathione-dependent PGE(2) synthase (mPGES) has been shown to be a terminal enzyme of the cyclooxygenase-2-mediated PGE(2) biosynthesis. Here we identified mPGES as a molecule that is induced by LPS in macrophages. The expression of mPGES was not induced by LPS in mice lacking Toll-like receptor 4 or MyD88. Furthermore, mice deficient in NF-IL6 showed neither induction of mPGES nor biosynthesis of PGE(2) in response to LPS, indicating that mPGES expression in response to LPS is regulated by a Toll-like receptor 4/MyD88/NF-IL6-dependent signaling pathway. We generated mPGES-deficient mice and investigated the role of mPGES in vivo. The mice showed no augmentation of the PGE(2) production in response to LPS. However, they were not impaired in the LPS-induced production of inflammatory cytokines and showed normal response to the LPS-induced shock. Thus, mPGES is critically involved in the biosynthesis of PGE(2) induced by LPS, but is dispensable for the modulation of inflammatory responses.

title: MDA5 and PTPN2, two candidate genes for type 1 diabetes, modify pancreatic β-cell responses to the viral by-product double-stranded RNA

text: beta-Cell destruction in type 1 diabetes (T1D) is at least in part consequence of a 'dialog' between beta-cells and immune system. This dialog may be affected by the individual's genetic background. We presently evaluated whether modulation of MDA5 and PTPN2, two candidate genes for T1D, affects beta-cell responses to double-stranded RNA (dsRNA), a by-product of viral replication. These genes were selected following comparison between known candidate genes for T1D and genes expressed in pancreatic beta-cells, as identified in previous array analysis. INS-1E cells and primary fluorescence-activated cell sorting-purified rat beta-cells were transfected with small interference RNAs (siRNAs) targeting MDA5 or PTPN2 and subsequently exposed to intracellular synthetic dsRNA (polyinosinic-polycitidilic acid-PIC). Real-time RT-PCR, western blot and viability assays were performed to characterize gene/protein expression and viability. PIC increased MDA5 and PTPN2 mRNA expression, which was inhibited by the specific siRNAs. PIC triggered apoptosis in INS-1E and primary beta-cells and this was augmented by PTPN2 knockdown (KD), although inhibition of MDA5 did not modify PIC-induced apoptosis. In contrast, MDA5 silencing decreased PIC-induced cytokine and chemokine expression, although inhibition of PTPN2 induced minor or no changes in these inflammatory mediators. These findings indicate that changes in MDA5 and PTPN2 expression modify beta-cell responses to dsRNA. MDA5 regulates inflammatory signals, whereas PTPN2 may function as a defence mechanism against pro-apoptotic signals generated by dsRNA. These two candidate genes for T1D may thus modulate beta-cell apoptosis and/or local release of inflammatory mediators in the course of a viral infection by acting, at least in part, at the pancreatic beta-cell level.

title: The kinase TAK1 integrates antigen and cytokine receptor signaling for T cell development, survival and function

text: The kinase TAK1 is critical for innate and B cell immunity. The function of TAK1 in T cells is unclear, however. We show here that T cell–specific deletion of the gene encoding TAK1 resulted in reduced development of thymocytes, especially of regulatory T cells expressing the transcription factor Foxp3. In mature thymocytes, TAK1 was required for interleukin 7–mediated survival and T cell receptor–dependent activation of transcription factor NF-κB and the kinase Jnk. In effector T cells, TAK1 was dispensable for T cell receptor–dependent NF-κB activation and cytokine production, but was important for proliferation and activation of the kinase p38 in response to interleukins 2, 7 and 15. Thus, TAK1 is essential for the integration of T cell receptor and cytokine signals to regulate the development, survival and function of T cells.

title: Chimeric Antigen Receptor-Redirected Regulatory T Cells Suppress Experimental Allergic Airway Inflammation, a Model of Asthma

text: Cellular therapy with chimeric antigen receptor (CAR)-redirected cytotoxic T cells has shown impressive efficacy in the treatment of hematologic malignancies. We explored a regulatory T cell (Treg)-based therapy in the treatment of allergic airway inflammation, a model for asthma, which is characterized by an airway hyper-reactivity (AHR) and a chronic, T helper-2 (Th2) cell-dominated immune response to allergen. To restore the immune balance in the lung, we redirected Tregs by a CAR toward lung epithelia in mice upon experimentally induced allergic asthma, closely mimicking the clinical situation. Adoptively transferred CAR Tregs accumulated in the lung and in tracheobronchial lymph nodes, reduced AHR and diminished eosinophilic airway inflammation, indicated by lower cell numbers in the bronchoalveolar lavage fluid and decreased cell infiltrates in the lung. CAR Treg cells furthermore prevented excessive pulmonary mucus production as well as increase in allergen-specific IgE and Th2 cytokine levels in exposed animals. CAR Tregs were more efficient in controlling asthma than non-modified Tregs, indicating the pivotal role of specific Treg cell activation in the affected organ. Data demonstrate that lung targeting CAR Treg cells ameliorate key features of experimental airway inflammation, paving the way for cell therapy of severe allergic asthma.

title: Paracrine effects of direct intramyocardial implantation of bone marrow derived cells to enhance neovascularization in chronic ischaemic myocardium.

text:
OBJECTIVE To determine the optimal bone marrow (BM) cell types, and their potential mechanisms of action for neovascularization in chronic ischaemic myocardium.
 METHODS AND RESULTS The functional effects, angiogenic potential and cytokine expression of direct intramyocardial implantation of autologous BM CD31-positive endothelial progenitor cells (EPC, n=9), BM mononuclear cells (MNCs, n=9), and saline (n=9) were compared in a swine model of chronic ischaemic myocardium. Autologous BM cells were harvested and catheter-based electromechanical mapping-guided direct intramyocardial injection was performed to target ischaemic myocardium. After 12 weeks, injection of BM-MNC resulted in significant improvements in left ventricular dP/dt (+21+/-8%, P=0.032), left ventricular pressure (+17+/-4%, P=0.048) and regional microsphere myocardial perfusion over ischaemic endocardium (+74+/-28%, P<0.05) and epicardium (+73+/-29%, P<0.05). No significant effects were observed following injection of BM-EPC or saline. Capillary density (1132+/-69 versus 903+/-44 per mm(2), P=0.047) and expression of mRNA of vascular endothelial growth factor (VEGF, 32.3+/-5.6 versus 13.1+/-3.7, P<0.05,) and angiopoietin-2 (23.9+/-3.6 versus 13.7+/-3.1, P<0.05) in ischaemic myocardium was significantly greater in the BM-MNC group than the saline group. The capillary density in ischaemic myocardium demonstrated a significant positive correlation with VEGF expression (r=0.61, P<0.001).
 CONCLUSION Catheter-based direct intramyocardial injection of BM-MNC enhanced angiogenesis more effectively than BM-EPC or saline, possibly via a paracrine effect, with increased expression of VEGF that subsequently improved cardiac performance of ischaemic myocardium.