bluuebunny/crossref_metadata_2025 huggingface dataset:
IL-13 Is Pivotal in the Fibro-Obliterative Process of Bronchiolitis Obliterans Syndrome
Authors: Keane Michael P. , Gomperts Brigitte N. , Weigt Samuel , Xue Ying Ying , Burdick Marie D. , Nakamura Hiromi , Zisman David A. , Ardehali Abbas , Saggar Rajan , Lynch Joseph P. , Hogaboam Cory , Kunkel Steven L. , Lukacs Nicholas W. , Ross David J. , Grusby Michael J. , Strieter Robert M. , Belperio John A.
Published: April 2014

Acute allograft rejection is considered to be a predominately type 1 immune mediated response to the donor alloantigen. However, the type 2 immune mediated response has been implicated in multiple fibroproliferative diseases. Based on the fibro-obliterative lesion found during bronchiolitis obliterans syndrome (BOS), we hypothesized that the type 2 immune mediated response is involved in chronic lung allograft rejection. Specifically, whereas acute rejection is, in part, a type 1 immune response, chronic rejection is, in part, a type 2 immune response. We found the type 2 cytokine, IL-13, to be elevated and biologically active in human bronchoalveolar lavage fluid during BOS. Translational studies using a murine model of BOS demonstrated increased expression of IL-13 and its receptors that paralleled fibro-obliteration. In addition, in vivo neutralization of IL-13 reduced airway allograft matrix deposition and murine BOS, by a mechanism that was independent of IL-4. Furthermore, using IL-13Rα2−/− mice, we found increased fibro-obliteration. Moreover, anti-IL-13 therapy in combination with cyclosporin A had profound effects on reducing murine BOS. This supports the notion that IL-13 biological axis plays an important role during the pathogenesis of BOS independent of the IL-4 biological axis.
C-Reactive Protein-Mediated Suppression of Nephrotoxic Nephritis: Role of Macrophages, Complement, and Fcγ Receptors
Authors: Rodriguez Wilfredo , Mold Carolyn , Kataranovski Milena , Hutt Julie A. , Marnell Lorraine L. , Verbeek J. Sjef , Du Clos Terry W.
Published: April 2014

C-reactive protein (CRP) is a member of the pentraxin family of proteins and an acute phase reactant. CRP modulates the response to inflammatory stimuli including LPS and C5a. We recently demonstrated that CRP prevents and reverses proteinuria in accelerated nephrotoxic nephritis (NTN). NTN is a model of active inflammatory immune complex-mediated nephritis induced by injection of antiglomerular basement membrane. CRP treatment prevented the induction of NTN in C57BL/6 (B6) mice, increased survival, and reversed ongoing nephritis. Protection was associated with a decrease in IL-1β and chemokines in the kidney and peritoneal cells as measured by quantitative RT-PCR. However, IL-10−/− mice were not protected by CRP either when given before disease onset or when disease activity was maximal. FcγRI−/− mice developed NTN, but were only transiently protected by CRP treatment. This transient protection was abrogated by cobra venom factor depletion of complement from FcγRI−/− mice. However, complement depletion did not prevent CRP-mediated protection in B6 mice, and CRP was protective in C3−/− mice. The role of macrophages in the protection provided by CRP was tested by treating B6 mice with liposomes containing clodronate. Clodronate-containing liposomes deplete mice of splenic and hepatic macrophages for 5–7 days. Pretreatment of NTN mice with clodronate but not control liposomes completely prevented CRP-mediated protection. These studies suggest that CRP mediates protection from NTN through the induction of IL-10 and that macrophages are required. In addition, FcγRI plays an important role but is not the sole mediator of CRP-mediated protection.
Prolonged, NK Cell-Mediated Antitumor Effects of Suicide Gene Therapy Combined with Monocyte Chemoattractant Protein-1 against Hepatocellular Carcinoma
Authors: Tsuchiyama Tomoya , Nakamoto Yasunari , Sakai Yoshio , Marukawa Yohei , Kitahara Masaaki , Mukaida Naofumi , Kaneko Shuichi
Published: April 2014

Tumor recurrence rates remain high after curative treatments for hepatocellular carcinoma (HCC). Immunomodulatory agents, including chemokines, are believed to enhance the antitumor effects of tumor cell apoptosis induced by suicide gene therapy. We therefore evaluated the immunomodulatory effects of a bicistronic recombinant adenovirus vector (rAd) expressing both HSV thymidine kinase and MCP-1 on HCC cells. Using an athymic nude mouse model (BALB/c-nu/nu), primary s.c. tumors (HuH7; human HCC cells) were completely eradicated by rAd followed by treatment with ganciclovir. The same animals were subsequently rechallenged with HCC cells, tumor development was monitored, and the recruitment or activation of NK cells was analyzed immunohistochemically or by measuring IFN-γ mRNA expression. Tumor growth was markedly suppressed as compared with that in mice treated with a rAd expressing the HSV thymidine kinase gene alone (p < 0.001). Suppression of tumor growth was associated with the elevation of serum IL-12 and IL-18. During suppression, NK cells were recruited exclusively, and Th1 cytokine gene expression was enhanced in tumor tissues. The antitumor activity, however, was abolished either when the NK cells were inactivated with anti-asialo GM1 Ab or when anti-IL-12 and anti-IL-18 Abs were administered. These results indicate that suicide gene therapy, together with delivery of MCP-1, eradicates HCC cells and exerts prolonged NK cell-mediated antitumor effects in a model of HCC, suggesting a plausible strategy to prevent tumor recurrence.
An Inflammatory Pathway of IFN-γ Production in Coronary Atherosclerosis
Authors: Ranjbaran Hooman , Sokol Seth I. , Gallo Amy , Eid Raymond E. , Iakimov Alexander O. , D’Alessio Alessio , Kapoor John R. , Akhtar Shamsuddin , Howes Christopher J. , Aslan Mihaela , Pfau Steven , Pober Jordan S. , Tellides George
Published: April 2014

Inflammation is associated with the pathogenesis of coronary atherosclerosis, although the mechanisms remain unclear. We investigated whether cytokine secretion by innate immune responses could contribute to the production of proarteriosclerotic Th1-type cytokines in human coronary atherosclerosis. Cytokines were measured by ELISA in the plasma of patients with coronary atherosclerosis undergoing cardiac catheterization. IL-18 was detected in all subjects, whereas a subset of patients demonstrated a coordinated induction of other IFN-γ-related cytokines. Specifically, elevated plasma levels of IL-12 correlated with that of IFN-γ and IFN-γ-inducible chemokines, defining an IFN-γ axis that was activated independently of IL-6 or C-reactive protein. Systemic inflammation triggered by cardiopulmonary bypass increased plasma levels of the IFN-γ axis, but not that of IL-18. Activation of the IFN-γ axis was not associated with acute coronary syndromes, but portended increased morbidity and mortality after 1-year follow-up. IL-12 and IL-18, but not other monokines, elicited secretion of IFN-γ and IFN-γ-inducible chemokines in human atherosclerotic coronary arteries maintained in organ culture. T cells were the principal source of IFN-γ in response to IL-12/IL-18 within the arterial wall. This inflammatory response did not require, but was synergistic with and primed for TCR signals. IL-12/IL-18-stimulated T cells displayed a cytokine-producing, nonproliferating, and noncytolytic phenotype, consistent with previous descriptions of lymphocytes in stable plaques. In contrast to cognate stimuli, IL-12/IL-18-dependent IFN-γ secretion was prevented by a p38 MAPK inhibitor and not by cyclosporine. In conclusion, circulating IL-12 may provide a mechanistic link between inflammation and Th1-type cytokine production in coronary atherosclerosis.
Apoptotic Splenocytes Drive the Autoimmune Response to Poly(ADP-ribose) Polymerase 1 in a Murine Model of Lupus
Authors: Grader-Beck Thomas , Casciola-Rosen Livia , Lang Thomas J. , Puliaev Roman , Rosen Antony , Via Charles S.
Published: April 2014

Although defects in apoptosis have been linked to both human and murine lupus, the exact mechanisms remain unknown. Moreover, it is not clear whether such defects are primary or secondary events in disease pathogenesis. To address these issues, we used an induced model of murine lupus, the parent-into-F1 model of chronic graft-versus-host disease (cGVHD) in which a lupus-like phenotype highly similar to human systemic lupus erythematosus is reliably induced in normal F1 mice. We addressed the role of nuclear Ags modified by caspases during apoptosis as potential targets of the autoantibody response and our results identify poly(ADP-ribose) polymerase 1 (PARP-1) as a frequently targeted autoantigen. Additional proteins cleaved during apoptosis were also targeted by the immune response. Importantly, female mice exhibited significantly greater numbers of apoptotic cells in germinal centers and higher serum anti-PARP-1 Ab levels compared with male cGVHD mice. Serum anti-PARP-1 levels in male cGVHD mice could be elevated to levels comparable to those of female cGVHD mice by the injection of apoptotic syngeneic F1 splenocytes early in the disease course. These results provide a mechanism by which lupus autoantibodies target apoptotic molecules. Specifically, T cell-driven polyclonal B cell activation characteristic of systemic lupus erythematosus is sufficient to saturate otherwise normal apoptotic clearance mechanisms, permitting apoptotic material to accumulate, serve as autoantigens, and drive autoantibody production.
Cutting Edge: Transplant Tolerance Induced by Anti-CD45RB Requires B Lymphocytes
Authors: Deng Shaoping , Moore Daniel J. , Huang Xiaolun , Lian Moh-Moh , Mohiuddin Muhammad , Velededeoglu Ergun , Lee Major K. , Sonawane Samsher , Kim James , Wang Jing , Chen Haiying , Corfe Steven A. , Paige Christopher , Shlomchik Mark , Caton Andrew , Markmann James F.
Published: April 2014

Selective interference with the CD45RB isoform by mAb (anti-CD45RB) reliably induces donor-specific tolerance. Although previous studies suggest participation of regulatory T cells, a mechanistic understanding of anti-CD45RB-induced tolerance is lacking. We report herein the unexpected finding that tolerance induced by this agent is not established in B cell-deficient mice but can be recovered by preemptive B lymphocyte transfer to B cell-deficient hosts. Using B cells from genetically modified donors to reconstitute B cell-deficient recipients, we evaluate the role of B lymphocyte-expressed CD45RB, T cell costimulatory molecules, and the production of Abs in this novel tolerance mechanism. Our data document an Ab-induced tolerance regimen that is uniquely B lymphocyte-dependent and suggest mechanistic contributions to tolerance development from the B cell compartment through interactions with T cells.
CD8 Blockade Promotes Antigen Responsiveness to Nontolerizing Antigen in Tolerant Mice by Inhibiting Apoptosis of CD4+ T Cells
Authors: Wang Zhuangzhi , Davies Joanna D.
Published: April 2014

Using the DO11.10 CD4+ TCR-transgenic mouse system, we have recently shown that CD8 blockade promotes the expansion of Ag-specific regulatory CD4+ T cells in mice made tolerant to OVA with anti-CD4 mAb. We now show that CD8 blockade is also critical to promoting responses to nontolerizing Ag in anti-CD4 mAb-treated tolerant mice. Previously published work shows that treatment with anti-CD4 mAb without CD8 blockade induces Ag-specific tolerance. We now show that, in addition to inducing tolerance, anti-CD4 mAb treatment also significantly reduces responsiveness to irrelevant, nontolerizing Ag, and this unresponsiveness is associated with significant apoptosis of the CD4+ T cells. Anti-CD4 mAb-induced apoptosis is inhibited by cotreatment with anti-CD8 mAb and responsiveness to irrelevant Ag is restored, while Ag-specific tolerance is maintained. These data suggest that CD8 blockade promotes responsiveness to nontolerizing Ags in tolerant mice by inhibiting CD4+ T cell apoptosis.
Enhanced IL-10 Production by TLR4- and TLR2-Primed Dendritic Cells upon TLR Restimulation
Authors: Yanagawa Yoshiki , Onoé Kazunori
Published: April 2014

LPS tolerance has been investigated extensively in monocytes/macrophages. However, the LPS restimulation studies are not well documented in dendritic cells (DCs). In the present study, we investigated influences of TLR restimulation using murine bone marrow-derived DCs. Purified bone marrow-derived DCs (>98% CD11c+ B220−) were stimulated with TLR4 and TLR2 ligands for 24 h and then cultured with medium alone for 48 h as a resting interval (TLR4,2-primed DCs). The TLR4-MD2 expression was markedly reduced immediately after the TLR stimulation, but was restored following the resting interval. The TLR4,2-primed DCs exhibited significantly enhanced IL-10 production, but markedly diminished IL-12p40 production upon TLR4 restimulation compared with naive (unprimed) DCs. TLR4-mediated activation of p38 MAPK was markedly suppressed, whereas that of ERK1/2 was enhanced in the TLR4,2-primed DCs compared with naive DCs. Blocking the activation of ERK1/2 with U0126 reduced the enhanced IL-10 production by the TLR4,2-primed DCs upon the TLR4 restimulation. The U0126 showed no significant effects on the IL-12p40 production. Thus, the enhanced ERK1/2 activation appears to be, at least in part, responsible for the enhanced IL-10 production in the TLR4,2-primed DCs. In addition, TNFR-associated factor 3 expression was significantly up-regulated in the TLR4,2-primed DCs compared with that in naive DCs. We demonstrated in this study that DCs primed with TLR4 and TLR2 ligands and rested for 48 h showed enhanced IL-10 production upon TLR4 restimulation. The enhanced IL-10 production by the TLR4,2-primed DCs may be attributed to the altered balance of intracellular signaling pathways via p38 MAPK, ERK1/2, and TNFR-associated factor 3 upon TLR restimulation.
Host NKT Cells Can Prevent Graft-versus-Host Disease and Permit Graft Antitumor Activity after Bone Marrow Transplantation
Authors: Pillai Asha B. , George Tracy I. , Dutt Suparna , Teo Pearline , Strober Samuel
Published: April 2014

Allogeneic bone marrow transplantation is a curative treatment for leukemia and lymphoma, but graft-vs-host disease (GVHD) remains a major complication. Using a GVHD protective nonmyeloablative conditioning regimen of total lymphoid irradiation and antithymocyte serum (TLI/ATS) in mice that has been recently adapted to clinical studies, we show that regulatory host NKT cells prevent the expansion and tissue inflammation induced by donor T cells, but allow retention of the killing activity of donor T cells against the BCL1 B cell lymphoma. Whereas wild-type hosts given transplants from wild-type donors were protected against progressive tumor growth and lethal GVHD, NKT cell-deficient CD1d−/− and Jα-18−/− host mice given wild-type transplants cleared the tumor cells but died of GVHD. In contrast, wild-type hosts given transplants from CD8−/− or perforin−/− donors had progressive tumor growth without GVHD. Injection of host-type NKT cells into Jα-18−/− host mice conditioned with TLI/ATS markedly reduced the early expansion and colon injury induced by donor T cells. In conclusion, after TLI/ATS host conditioning and allogeneic bone marrow transplantation, host NKT cells can separate the proinflammatory and tumor cytolytic functions of donor T cells.
Characterization of the IgD Binding Site of Encapsulated Haemophilus influenzae Serotype b
Authors: Samuelsson Martin , Hallström Teresia , Forsgren Arne , Riesbeck Kristian
Published: April 2014

Encapsulated Haemophilus influenzae is a causative agent of invasive disease, such as meningitis and septicemia. Several interactions exist between H. influenzae and the human host. H. influenzae has been reported to bind IgD in a nonimmune manner, but the responsible protein has not yet been identified. To define the binding site on IgD for H. influenzae, full-length IgD and four chimeric IgDs with interspersed IgG sequences and Ag specificity for dansyl chloride were expressed in stably transfected Chinese hamster ovary cells. The binding of recombinant IgD to a panel of encapsulated H. influenzae serotype b (Hib) and nontypeable strains were investigated using a whole cell ELISA and flow cytometry. IgD binding was detected in 50% of the encapsulated Hib strains examined, whereas nontypeable H. influenzae did not interact with IgD. Finally, mapping experiments using the chimeric IgD/IgG indicated that IgD CH1 aa 198–224 were involved in the interaction between IgD and H. influenzae. Thus, by using recombinant IgD and chimeras with defined Ag specificity, we have confirmed that Hib specifically binds IgD, and that this binding involves the IgD CH1 region.
Interaction with C4b-Binding Protein Contributes to Nontypeable Haemophilus influenzae Serum Resistance
Authors: Hallström Teresia , Jarva Hanna , Riesbeck Kristian , Blom Anna M.
Published: April 2014

Complement evasion by various mechanisms is important for microbial virulence and survival in the host. One strategy used by some pathogenic bacteria is to bind the complement inhibitor of the classical pathway, C4b-binding protein (C4BP). In this study, we have identified a novel interaction between nontypeable Haemophilus influenzae (NTHi) and C4BP, whereas the majority of the typeable H. influenzae (a-f) tested showed no binding. One of the clinical isolates, NTHi 506, displayed a particularly high binding of C4BP and was used for detailed analysis of the interaction. Importantly, a low C4BP-binding isolate (NTHi 69) showed an increased deposition of C3b followed by reduced survival as compared with NTHi 506 when exposed to normal human serum. The main isoform of C4BP contains seven identical α-chains and one β-chain linked together with disulfide bridges. Each α-chain is composed of eight complement control protein (CCP) modules and we have found that the NTHi 506 strain did not interact with rC4BP lacking CCP2 or CCP7 showing that these two CCPs are important for the binding. Importantly, C4BP bound to the surface of H. influenzae retained its cofactor activity as determined by analysis of C3b and C4b degradation. Taken together, NTHi interferes with the classical complement activation pathway by binding to C4BP.
Human Polymorphonuclear Leukocytes Inhibit Aspergillus fumigatus Conidial Growth by Lactoferrin-Mediated Iron Depletion
Authors: Zarember Kol A. , Sugui Janyce A. , Chang Yun C. , Kwon-Chung Kyung J. , Gallin John I.
Published: April 2014

Aspergillus fumigatus, a common mold, rarely infects humans, except during prolonged neutropenia or in cases of chronic granulomatous disease (CGD), a primary immunodeficiency caused by mutations in the NADPH oxidase that normally produces fungicidal reactive oxygen species. Filamentous hyphae of Aspergillus are killed by normal, but not CGD polymorphonuclear leukocytes (PMN); however, the few studies on PMN-mediated host defenses against infectious conidia (spores) of this organism have yielded conflicting results, some showing that PMN do not inhibit conidial growth, with others showing that they do, most likely using reactive oxygen species. Given that CGD patients are exposed daily to hundreds of viable A. fumigatus conidia, yet considerable numbers of them survive years without infection, we reasoned that PMN use ROS-independent mechanisms to combat Aspergillus. We show that human PMN from both normal controls and CGD patients are equipotent at arresting the growth of Aspergillus conidia in vitro, indicating the presence of a reactive oxygen species-independent factor(s). Cell-free supernatants of degranulated normal and CGD neutrophils both suppressed fungal growth and were found to be rich in lactoferrin, an abundant PMN secondary granule protein. Purified iron-poor lactoferrin at concentrations occurring in PMN supernatants (and reported in human mucosal secretions in vivo) decreased fungal growth, whereas saturation of lactoferrin or PMN supernatants with iron, or testing in the presence of excess iron in the form of ferritin, completely abolished activity against conidia. These results demonstrate that PMN lactoferrin sequestration of iron is important for host defense against Aspergillus.
Dominance and Diversity in the Primary Human CD4 T Cell Response to Replication-Competent Vaccinia Virus
Authors: Jing Lichen , Chong Tiana M. , Byrd Benjamin , McClurkan Christopher L. , Huang Jay , Story Brian T. , Dunkley Karissa M. , Aldaz-Carroll Lydia , Eisenberg Roselyn J. , Cohen Gary H. , Kwok William W. , Sette Allesandro , Koelle David M.
Published: April 2014

Vaccination with replication-competent vaccinia protects against heterologous orthopoxvirus challenge. CD4 T cells have essential roles helping functionally important Ab and CD8 antiviral responses, and contribute to the durability of vaccinia-specific memory. Little is known about the specificity, diversity, or dominance hierarchy of orthopoxvirus-specific CD4 T cell responses. We interrogated vaccinia-reactive CD4 in vitro T cell lines with vaccinia protein fragments expressed from an unbiased genomic library, and also with a panel of membrane proteins. CD4 T cells from three primary vaccinees reacted with 44 separate antigenic regions in 35 vaccinia proteins, recognizing 8 to 20 proteins per person. The integrated responses to the Ags that we defined accounted for 49 to 81% of the CD4 reactivity to whole vaccinia Ag. Individual dominant Ags drove up to 30% of the total response. The gene F11L-encoded protein was immunodominant in two of three subjects and is fragmented in a replication-incompetent vaccine candidate. The presence of protein in virions was strongly associated with CD4 antigenicity. These findings are consistent with models in which exogenous Ag drives CD4 immunodominance, and provides tools to investigate the relationship between Ab and CD4 T cell specificity for complex pathogens.
The Polymorphism P315L of Human Toll-Like Receptor 1 Impairs Innate Immune Sensing of Microbial Cell Wall Components
Authors: Omueti Katherine O. , Mazur Daniel J. , Thompson Katherine S. , Lyle Elizabeth A. , Tapping Richard I.
Published: April 2014

As a pattern recognition receptor, TLR1 mediates innate immune responses to a variety of microbial cell wall components including bacterial lipoproteins. We have previously shown that the central region of the extracellular domain of human TLR1, comprising leucine-rich repeat (LRR) motifs 9–12, is required for the sensing of bacterial lipopeptides. In this study, we have investigated three nonsynonymous single nucleotide polymorphisms (SNPs) located in this region of TLR1 by generating these variants and examining receptor function. We have found that a variant of TLR1 based upon the SNP P315L, located in the loop of LRR motif 11 (LRR11), is greatly impaired in mediating responses to lipopeptides and a variety of other bacterial agonists for this receptor. Despite normal cell surface expression, the P315L variant also fails to bind to GD2.F4, a commonly used anti-TLR1 mAb. Although a number of amino acid substitutions at position 315 impair receptor function, the leucine substitution has the strongest deleterious effect. GD2.F4 inhibits agonist-induced activation of TLR1, supporting a crucial role for the loop of LRR11 in receptor function. These results also suggest that the P315L SNP may predispose certain individuals to infectious diseases for which the sensing of microbial cell components by TLR1 is critical to innate immune defense.
Paracellular Permeability Restricts Airway Epithelial Responses to Selectively Allow Activation by Mediators at the Basolateral Surface
Authors: Humlicek Alicia L. , Manzel Lori J. , Chin Cecilia L. , Shi Lei , Excoffon Katherine J. D. A. , Winter Michael C. , Shasby D. Michael , Look Dwight C.
Published: April 2014

Respiratory pathogens and toxins often assault the lung from the airway lumen. Airway epithelia may initiate and amplify inflammation in response to these attacks, but under certain conditions confinement of inflammation to the airway lumen may be beneficial to the host. Accordingly, we hypothesized that airway epithelial polarity allows different responses to basolateral vs apical stimuli that may modulate inflammation. Using primary human airway epithelial cells differentiated at an air-liquid interface in culture, we found that responses to several cytokines required basolateral mediator application. In contrast, responses to Haemophilus influenzae occurred after either basolateral or apical interaction with airway epithelia. Experiments focused on IFN-γ receptor polarity confirmed its predominant basolateral location in cultured airway epithelia as well as in normal human airway tissue. Furthermore, physical and pharmacologic disruption of barrier function in airway epithelia allowed responses to apical application of IFN-γ and other cytokines. These in vitro studies directly correlated with experiments in mice in which an airway epithelial response to IFN-γ injected into the airway lumen was seen only after disruption of barrier function. The results indicate that airway epithelia with intact barrier function restrict inflammatory responses by limitation of cell activation through requiring interaction of selected mediators with the basolateral surface. However, loss of barrier integrity allows epithelial responses to these mediators if located in the airway lumen to amplify airway defenses.
Mice Lacking Three Myeloid Colony-Stimulating Factors (G-CSF, GM-CSF, and M-CSF) Still Produce Macrophages and Granulocytes and Mount an Inflammatory Response in a Sterile Model of Peritonitis
Authors: Hibbs Margaret L. , Quilici Cathy , Kountouri Nicole , Seymour John F. , Armes Jane E. , Burgess Antony W. , Dunn Ashley R.
Published: April 2014

To assess the combined role of G-CSF, GM-CSF, and M-CSF in myeloid cell production, mice deficient in all three myeloid CSFs were generated (G−/−GM−/−M−/− mice). G−/−GM−/−M−/− mice share characteristics found in mice lacking individual cytokines: they are toothless and osteopetrotic and furthermore acquire alveolar proteinosis that is more severe than that found in either GM−/− or G−/−GM−/− mice. G−/−GM−/−M−/− mice have a significantly reduced lifespan, which is prolonged by antibiotic administration, suggesting compromised ability to control bacterial infection. G−/−GM−/−M−/− mice have circulating neutrophils and monocytes, albeit at significantly reduced numbers compared with wild-type mice, but surprisingly, have more circulating monocytes than M−/− mice and more circulating neutrophils than G−/−GM−/− mice. Due to severe osteopetrosis, G−/−GM−/−M−/− mice show diminished numbers of myeloid cells, myeloid progenitors, and B lymphocytes in the bone marrow, but have significantly enhanced compensatory splenic hemopoiesis. Although G−/−GM−/−M−/− mice have a profound deficiency of myeloid cells in the resting peritoneal cavity, the animals mount a moderate cellular response in a model of sterile peritonitis. These data establish that in the absence of G-CSF, GM-CSF, and M-CSF, additional growth factor(s) can stimulate myelopoiesis and acute inflammatory responses.
Loss of DExD/H Box RNA Helicase LGP2 Manifests Disparate Antiviral Responses
Authors: Venkataraman Thiagarajan , Valdes Maikel , Elsby Rachel , Kakuta Shigeru , Caceres Gisela , Saijo Shinobu , Iwakura Yoichiro , Barber Glen N.
Published: April 2014

The DExD/H box RNA helicase retinoic acid-inducible gene I (RIG-I) and the melanoma differentiation-associated gene 5 (MDA5) are key intracellular receptors that recognize virus infection to produce type I IFN. A third helicase gene, Lgp2, is homologous to Rig-I and Mda5 but lacks a caspase activation and recruitment domain. We generated Lgp2-deficient mice and report that the loss of this gene greatly sensitizes cells to cytosolic polyinosinic/polycytidylic acid-mediated induction of type I IFN. However, negative feedback inhibition of IFN-β transcription was found to be normal in the absence of LGP2, indicating that LGP2 is not the primary negative regulator of type I IFN production. Our data further indicate that Lgp2−/− mice exhibited resistance to lethal vesicular stomatitis virus infection, a virus whose replicative RNA intermediates are recognized specifically by RIG-I rather than by MDA5 to trigger the production of type I IFN. However, mice lacking LGP2 were observed to exhibit a defect in type I IFN production in response to infection by the encephalomyocarditis virus, the replication of which activates MDA5-dependent innate immune responses. Collectively, our data indicate a disparate regulatory role for LGP2 in the triggering of innate immune signaling pathways following RNA virus infection.
TLR2 Mediates Neuroinflammation and Neuronal Damage
Authors: Hoffmann Olaf , Braun Johann S. , Becker Doreen , Halle Annett , Freyer Dorette , Dagand Emilie , Lehnardt Seija , Weber Joerg R.
Published: April 2014

Innate immunity relies on pattern recognition receptors to detect the presence of infectious pathogens. In the case of Gram-positive bacteria, binding of bacterial lipopeptides to TLR2 is currently regarded as an important mechanism. In the present study, we used the synthetic bacterial lipopeptide Pam3CysSK4, a selective TLR2 agonist, to induce meningeal inflammation in rodents. In a 6-h rat model, intrathecal application of Pam3CysSK4 caused influx of leukocytes into the cerebrospinal fluid (CSF) and induced a marked increase of regional cerebral blood flow and intracranial pressure. In wild-type mice, we observed CSF pleocytosis and an increased number of apoptotic neurons in the dentate gyrus 24 h after intrathecal challenge. Inflammation and associated neuronal loss were absent in TLR2 knockout mice. In purified neurons, cytotoxicity of Pam3CysSK4 itself was not observed. Exposure of microglia to Pam3CysSK4 induced neurotoxic properties in the supernatant of wild-type, but not TLR2-deficient microglia. We conclude that TLR2-mediated signaling is sufficient to induce the host-dependent key features of acute bacterial meningitis. Therefore, synthetic lipopeptides are a highly specific tool to study mechanisms of TLR2-driven neurodegeneration in vivo.
Th1- and Th2-Dependent Endothelial Progenitor Cell Recruitment and Angiogenic Switch in Asthma
Authors: Asosingh Kewal , Swaidani Shadi , Aronica Mark , Erzurum Serpil C.
Published: April 2014

Increased numbers of submucosal vessels are a consistent pathologic component of asthmatic airway remodeling. However, the relationship between new vessel formation and asthmatic inflammatory response is unknown. We hypothesized that angiogenesis is a primary event during the initiation of airway inflammation and is linked to the recruitment of bone marrow-derived endothelial progenitor cells (EPC). To test this hypothesis, circulating EPC and EPC-derived endothelial cell colony formation of individuals with asthma or allergic rhinitis and health controls was evaluated. Circulating EPC were increased in asthma, highly proliferative, and exhibited enhanced incorporation into endothelial cell tubes as compared with controls. In an acute allergen challenge murine asthma model, EPC mobilization occurred within hours of challenge and mobilized EPC were selectively recruited into the challenged lungs of sensitized animals, but not into other organs. EPC recruitment was Th1 and Th2 dependent and was temporally associated with an increased microvessel density that was noted within 48 h of allergen challenge, indicating an early switch to an angiogenic lung environment. A chronic allergen challenge model provided evidence that EPC recruitment to the lung persisted and was associated with increasing microvessel density over time. Thus, a Th1- and Th2-dependent angiogenic switch with EPC mobilization, recruitment, and increased lung vessel formation occurs early but becomes a sustained and cumulative component of the allergen-induced asthmatic response.
The Alternative Pathway of Complement Activation Is Critical for Blister Induction in Experimental Epidermolysis Bullosa Acquisita
Authors: Mihai Sidonia , Chiriac Mircea T. , Takahashi Kazue , Thurman Joshua M. , Holers V. Michael , Zillikens Detlef , Botto Marina , Sitaru Cassian
Published: April 2014

Epidermolysis bullosa acquisita is a subepidermal blistering disease associated with tissue-bound and circulating autoantibodies against type VII collagen, a major constituent of the dermal-epidermal junction. The passive transfer of Abs against type VII collagen into mice induces a subepidermal blistering disease dependent upon activation of terminal complement components. To further dissect the role of the different complement activation pathways in this model, we injected C1q-deficient, mannan-binding lectin-deficient, and factor B-deficient mice with rabbit Abs against murine type VII collagen. The development and evolution of blistering had a similar pattern in mannan-binding lectin-deficient and control mice and was initially only marginally less extensive in C1q-deficient mice compared with controls. Importantly, factor B-deficient mice developed a delayed and significantly less severe blistering disease compared with factor B-sufficient mice. A significantly lower neutrophilic infiltration was observed in factor B-deficient mice compared with controls and local reconstitution with granulocytes restored the blistering disease in factor B-deficient mice. Our study provides the first direct evidence for the involvement of the alternative pathway in an autoantibody-induced blistering disease and should facilitate the development of new therapeutic strategies for epidermolysis bullosa acquisita and related autoimmune diseases.
System xc− and Glutamate Transporter Inhibition Mediates Microglial Toxicity to Oligodendrocytes
Authors: Domercq María , Sánchez-Gómez María Victoria , Sherwin Catherine , Etxebarria Estibaliz , Fern Robert , Matute Carlos
Published: April 2014

Elevated levels of extracellular glutamate cause excitotoxic oligodendrocyte cell death and contribute to progressive oligodendrocyte loss and demyelination in white matter disorders such as multiple sclerosis and periventricular leukomalacia. However, the mechanism by which glutamate homeostasis is altered in such conditions remains elusive. We show here that microglial cells, in their activated state, compromise glutamate homeostasis in cultured oligodendrocytes. Both activated and resting microglial cells release glutamate by the cystine-glutamate antiporter system xc−. In addition, activated microglial cells act to block glutamate transporters in oligodendrocytes, leading to a net increase in extracellular glutamate and subsequent oligodendrocyte death. The blocking of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptors or the system xc− antiporter prevented the oligodendrocyte injury produced by exposure to LPS-activated microglial cells in mixed glial cultures. In a whole-mount rat optic nerve, LPS exposure produced wide-spread oligodendrocyte injury that was prevented by AMPA/kainate receptor block and greatly reduced by a system xc− antiporter block. The cell death was typified by swelling and disruption of mitochondria, a feature that was not found in closely associated axonal mitochondria. Our results reveal a novel mechanism by which reactive microglia can contribute to altering glutamate homeostasis and to the pathogenesis of white matter disorders.
Cutting Edge: Small Molecule CD40 Ligand Mimetics Promote Control of Parasitemia and Enhance T Cells Producing IFN-γ during ExperimentalTrypanosoma cruziInfection
Authors: Habib Mohammed , Rivas Magali Noval , Chamekh Mustapha , Wieckowski Sébastien , Sun Weimin , Bianco Alberto , Trouche Nathalie , Chaloin Olivier , Dumortier Hélène , Goldman Michel , Guichard Gilles , Fournel Sylvie , Vray Bernard
Published: April 2014

Host resistance to Trypanosoma cruzi infection depends on a type 1 response characterized by a strong production of IL-12 and IFN-γ. Amplifying this response through CD40 triggering results in control of parasitemia. Two newly synthesized molecules (<3 kDa) mimicking trimeric CD40L (mini CD40Ls-1 and -2) bind to CD40, activate murine dendritic cells, and elicit IL-12 production. Wild-type but not CD40 knockout mice exhibited a sharp decrease of parasitemia and mortality when inoculated with T. cruzi mixed with miniCD40Ls. Moreover, the immunosuppression induced by T. cruzi infection was impaired in mice treated with miniCD40Ls, as shown by proliferation of splenic lymphocytes, percentage of CD8+ T cells, and IFN-γ production. Mice surviving T. cruzi infection in the presence of miniCD40L-1 were immunized against a challenge infection. Our results indicate that CD40L mimetics are effective in vivo and promote the control of T. cruzi infection by overcoming the immunosuppression usually induced by the parasites.
Cutting Edge: Involvement of the Type I IFN Production and Signaling Pathway in Lipopolysaccharide-Induced IL-10 Production
Authors: Chang Elmer Y. , Guo Beichu , Doyle Sean E. , Cheng Genhong
Published: April 2014

Macrophages respond to LPS by the rapid activation of proinflammatory cytokines that serve to initiate host defense against microbial invasion. To prevent injury to the host from excess production of these cytokines, IL-10 is up-regulated to feedback inhibit the proinflammatory response. However, the molecular events responsible for LPS-induced up-regulation of IL-10 remain to be elucidated. In this study, we provide evidence that production of and signaling by type I IFN is required for LPS-induced IL-10 up-regulation. In addition, we demonstrate that defect in type I IFN production and signaling results in a trend toward LPS-mediated superinduction of proinflammatory genes and cytokines in bone marrow-derived macrophages. Our findings suggest a novel anti-inflammatory role for the type I IFN production and signaling pathway in regulating LPS response in bone marrow-derived macrophages.
Human CD5 Protects Circulating Tumor Antigen-Specific CTL from Tumor-Mediated Activation-Induced Cell Death
Authors: Friedlein Grzegorz , El Hage Faten , Vergnon Isabelle , Richon Catherine , Saulnier Patrick , Lécluse Yann , Caignard Anne , Boumsell Laurence , Bismuth Georges , Chouaib Salem , Mami-Chouaib Fathia
Published: April 2014

We previously characterized several tumor-specific T cell clones from PBL and tumor-infiltrating lymphocytes of a lung cancer patient with identical TCR rearrangements and similar lytic potential, but with different antitumor response. A role of the TCR inhibitory molecule CD5 to impair reactivity of peripheral T cells against the tumor was found to be involved in this process. In this report, we demonstrate that CD5 also controls the susceptibility of specific T cells to activation-induced cell death (AICD) triggered by the tumor. Using a panel of tumor-infiltrating lymphocytes and PBL-derived clones expressing different levels of CD5, our results indicate that T lymphocyte AICD in response to the cognate tumor is inversely proportional to the surface expression level of CD5. They also suggest a direct involvement of CD5 in this process, as revealed by an increase in tumor-mediated T lymphocyte AICD following neutralization of the molecule with specific mAb. Mechanistically, our data indicate that down-regulation of FasL expression and subsequent inhibition of caspase-8 activation are involved in CD5-induced T cell survival. These results provide evidence for a role of CD5 in the fate of peripheral tumor-specific T cells and further suggest its contribution to regulate the extension of CTL response against tumor.
Tumor Exosomes Inhibit Differentiation of Bone Marrow Dendritic Cells
Authors: Yu Shaohua , Liu Cunren , Su Kaihong , Wang Jianhua , Liu Yuelong , Zhang Liming , Li Chuanyu , Cong Yingzi , Kimberly Robert , Grizzle William E. , Falkson Carla , Zhang Huang-Ge
Published: April 2014

The production of exosomes by tumor cells has been implicated in tumor-associated immune suppression. In this study, we show that, in mice, exosomes produced by TS/A murine mammary tumor cells target CD11b+ myeloid precursors in the bone marrow (BM) in vivo, and that this is associated with an accumulation of myeloid precursors in the spleen. Moreover, we demonstrate that TS/A exosomes block the differentiation of murine myeloid precursor cells into dendritic cells (DC) in vitro. Addition of tumor exosomes at day 0 led to a significant block of differentiation into DC, whereas addition at later time points was less effective. Similarly, exosomes produced by human breast tumor cells inhibited the differentiation of human monocytes in vitro. The levels of IL-6 and phosphorylated Stat3 were elevated 12 h after the tumor exosome stimulation of murine myeloid precursors, and tumor exosomes were less effective in inhibiting differentiation of BM cells isolated from IL-6 knockout mice. Addition of a rIL-6 to the IL-6 knockout BM cell culture restored the tumor exosome-mediated inhibition of DC differentiation. These data suggest that tumor exosome-mediated induction of IL-6 plays a role in blocking BM DC differentiation.
Role of Thrombospondin-1 in T Cell Response to Ocular Pigment Epithelial Cells
Authors: Futagami Yuri , Sugita Sunao , Vega Jose , Ishida Kazuhiro , Takase Hiroshi , Maruyama Kazuichi , Aburatani Hiroyuki , Mochizuki Manabu
Published: April 2014

Ocular pigment epithelium (PE) cells promote the generation of T regulators (PE-induced Treg cells). Moreover, T cells exposed to PE acquire the capacity to suppress the activation of bystander T cells via TGFβ. Membrane-bound TGFβ on iris PE cells interacts with TGFβ receptors on T cells, leading to the conversion of T cells to CD8+ Treg cells via a cell contact-dependent mechanism. Conversely, soluble forms of TGFβ produced by retinal PE cells can convert CD4+ T cells into Treg cells in a manner that is independent of cell contact. In this study, we looked at the expression of immunoregulatory factors (TGFβ, thrombospondins, CD59, IL-1 receptor antagonist, etc.) in PE cells as identified via an oligonucleotide microarray. Several thrombospondin-binding molecules were detected, and thus we focused subsequent analyses on thrombospondins. Via the conversion of latent TGFβ to an active form that appears to be mediated by thrombospondin 1 (TSP-1), cultured iris PE and retinal PE cells induce a PE-induced Treg cell fate. After conversion, both ocular PE and PE-induced Treg cells express TSP-1. Regulatory T cell generation was amplified when the T cells also expressed TSP-1. In addition, PE-induced Treg cells significantly suppressed activation of bystander T cells via TSP-1. These results strongly suggest that the ability of ocular PE and PE-induced Treg cells to suppress bystander T cells depends on their capacity to produce TSP-1. Thus, intraocular TSP-1 produced by both ocular parenchymal cells and regulatory T cells is essential for immune regulation in the eye.
Interaction of PRP4 with Krüppel-Like Factor 13 Regulates CCL5 Transcription
Authors: Huang Boli , Ahn Yong-Tae , McPherson Lisa , Clayberger Carol , Krensky Alan M.
Published: April 2014

Activation of resting T lymphocytes initiates differentiation into mature effector cells over 3–7 days. The chemokine CCL5 (RANTES) and its major transcriptional regulator, Krüppel-like factor 13 (KLF13), are expressed late (3–5 days) after activation in T lymphocytes. Using yeast two-hybrid screening of a human thymus cDNA library, PRP4, a serine/threonine protein kinase, was identified as a KLF13-binding protein. Specific interaction of KLF13 and PRP4 was confirmed by reciprocal coimmunoprecipitation. PRP4 is expressed in PHA-stimulated human T lymphocytes from days 1 and 7 with a peak at day 3. Using an in vitro kinase assay, it was found that PRP4 phosphorylates KLF13. Furthermore, although phosphorylation of KLF13 by PRP4 results in lower binding affinity to the A/B site of the CCL5 promoter, coexpression of PRP4 and KLF13 increases nuclear localization of KLF13 and CCL5 transcription. Finally, knock-down of PRP4 by small interfering RNA markedly decreases CCL5 expression in T lymphocytes. Thus, PRP4-mediated phosphorylation of KLF13 plays a role in the regulation of CCL5 expression in T lymphocytes.
Down-Regulation of the SWI/SNF Chromatin Remodeling Activity by TCR Signaling Is Required for Proper Thymocyte Maturation
Authors: Lee Kyoo Y. , Choi Young I. , Kim Jieun , Choi Jin W. , Sohn Dong H. , Lee Changjin , Jeon Sung H. , Seong Rho H.
Published: April 2014

The process of thymocyte development requires an exquisite regulation of many genes via transcription factors and chromatin remodeling activities. Even though the SWI/SNF chromatin remodeling complex has been thought to play important roles during thymocyte development, its known function is very limited. In this study, we show that the SWI/SNF chromatin remodeling activity is finely regulated during thymocyte maturation process, especially during thymocyte selections. We found that TCR signaling directly down-regulates mBRG1 and SWI3-related gene, the core components of murine SWI/SNF complex, during thymocyte maturation. Constitutive expression of SWI3-related gene in developing thymocytes attenuated the down-regulation of the SWI/SNF complex and resulted in a change in the expression of genes such as linker for activation of T cells and casitas B lineage lymphoma, which affected the TCR-mediated intracellular signaling pathway. The defects in TCR signaling resulted in the disruption of both positive and negative selections in specific TCR transgenic mice systems. Our results state, for the first time, that the chromatin remodeling activity needs to be finely controlled for proper thymocyte selection and maturation processes.
Cooperativity of Hydrophobic Anchor Interactions: Evidence for Epitope Selection by MHC Class II as a Folding Process
Authors: Ferrante Andrea , Gorski Jack
Published: April 2014

Peptide binding to MHC class II (MHCII) molecules is stabilized by hydrophobic anchoring and hydrogen bond formation. We view peptide binding as a process in which the peptide folds into the binding groove and to some extent the groove folds around the peptide. Our previous observation of cooperativity when analyzing binding properties of peptides modified at side chains with medium to high solvent accessibility is compatible with such a view. However, a large component of peptide binding is mediated by residues with strong hydrophobic interactions that bind to their respective pockets. If these reflect initial nucleation events they may be upstream of the folding process and not show cooperativity. To test whether the folding hypothesis extends to these anchor interactions, we measured dissociation and affinity to HLA-DR1 of an influenza hemagglutinin-derived peptide with multiple substitutions at major anchor residues. Our results show both negative and positive cooperative effects between hydrophobic pocket interactions. Cooperativity was also observed between hydrophobic pockets and positions with intermediate solvent accessibility, indicating that hydrophobic interactions participate in the overall folding process. These findings point out that predicting the binding potential of epitopes cannot assume additive and independent contributions of the interactions between major MHCII pockets and corresponding peptide side chains.