bluuebunny/crossref_metadata_2025 huggingface dataset:
Phospholipase Cβ Is Critical for T Cell Chemotaxis
Authors: Bach Tami L. , Chen Qing-Min , Kerr Wesley T. , Wang Yanfeng , Lian Lurong , Choi John K. , Wu Dianqing , Kazanietz Marcelo G. , Koretzky Gary A. , Zigmond Sally , Abrams Charles S.
Published: April 2014

Chemokines acting through G protein-coupled receptors play an essential role in the immune response. PI3K and phospholipase C (PLC) are distinct signaling molecules that have been proposed in the regulation of chemokine-mediated cell migration. Studies with knockout mice have demonstrated a critical role for PI3K in Gαi protein-coupled receptor-mediated neutrophil and lymphocyte chemotaxis. Although PLCβ is not essential for the chemotactic response of neutrophils, its role in lymphocyte migration has not been clearly defined. We compared the chemotactic response of peripheral T cells derived from wild-type mice with mice containing loss-of-function mutations in both of the two predominant lymphocyte PLCβ isoforms (PLCβ2 and PLCβ3), and demonstrate that loss of PLCβ2 and PLCβ3 significantly impaired T cell migration. Because second messengers generated by PLCβ lead to a rise in intracellular calcium and activation of PKC, we analyzed which of these responses was critical for the PLCβ-mediated chemotaxis. Intracellular calcium chelation decreased the chemotactic response of wild-type lymphocytes, but pharmacologic inhibition of several PKC isoforms had no effect. Furthermore, calcium efflux induced by stromal cell-derived factor-1α was undetectable in PLCβ2β3-null lymphocytes, suggesting that the migration defect is due to the impaired ability to increase intracellular calcium. This study demonstrates that, in contrast to neutrophils, phospholipid second messengers generated by PLCβ play a critical role in T lymphocyte chemotaxis.
Effective Treatment of Inflammatory Disease Models with Exosomes Derived from Dendritic Cells Genetically Modified to Express IL-4
Authors: Kim Seon Hee , Bianco Nicole R. , Shufesky William J. , Morelli Adrian E. , Robbins Paul D.
Published: April 2014

In this study, we demonstrate that genetically modified bone marrow-derived dendritic cells (DC) and exosomes derived from the DC, expressing either secreted IL-4 or membrane-bound IL-4, can reduce the severity and the incidence of established collagen-induced arthritis and inhibit inflammation of delayed-type hypersensitivity (DTH) in mice. The ability of the DC and DC-derived exosomes to suppress the DTH response was MHC class II and, in part, Fas ligand/Fas dependent. The DC-derived exosomes were internalized by CD11c+ DC in the dermis at the site of injection and in the draining lymph node as well as by CD11c+ DC and F4/80+ macrophages in the spleen. Moreover, adoptive transfer of CD11c+ or CD3+ splenic cells from mice treated with exosomes showed significant reduction of footpad swelling in the DTH model. These results demonstrate that administration of DC/IL-4 or exosomes derived from DC/IL-4 are able to modulate the activity of APC and T cells in vivo through a MHC class II and partly Fas ligand/Fas-dependent mechanism, resulting in effective treatment of established collagen-induced arthritis and suppression of the DTH inflammatory response. Thus, APC-derived exosomes could be used therapeutically for the treatment of autoimmune disease and inflammatory disorders.
Class IA Phosphoinositide 3-Kinase Modulates Basal Lymphocyte Motility in the Lymph Node
Authors: Matheu Melanie P. , Deane Jonathan A. , Parker Ian , Fruman David A. , Cahalan Michael D.
Published: April 2014

Recruitment of PI3K to the cell membrane is an indispensable step in normal lymphocyte proliferation and activation. In this study we identify PI3K as an important signaling molecule for maintaining basal T and B lymphocyte motility and homing in the intact lymph node. Pharmacological inhibition of PI3K catalytic isoforms exerted broad effects on basal lymphocyte motility, including changes in homing kinetics, localization of B cells within the lymph node, and reduced cell velocities. Lymphocytes deficient in either or both of the class IA PI3K regulatory subunits p85α and p85β also exhibited reduced velocities, with the magnitude of reduction depending upon both cell type and isoform specificity. B cells deficient in p85α exhibited gross morphological abnormalities that were not evident in cells treated with a PI3K inhibitor. Our results show, for the first time, that class IA PI3Ks play an important role in regulating basal lymphocyte motility and that p85α regulatory subunit expression is required to maintain B cell morphology in a manner independent of PI3K catalytic function. Moreover, we demonstrate distinct roles for catalytic domain function and class IA PI3K regulatory domain activity in lymphocyte motility, homing, and homeostatic localization of mature resting B cells.
The Recirculating B Cell Pool Contains Two Functionally Distinct, Long-Lived, Posttransitional, Follicular B Cell Populations
Authors: Cariappa Annaiah , Boboila Cristian , Moran Stewart T. , Liu Haoyuan , Shi Hai Ning , Pillai Shiv
Published: April 2014

Disparate models for the development of peripheral B cells may reflect significant heterogeneity in recirculating long-lived B cells that have not been previously accounted for. We show in this study that the murine recirculating B cell pool contains two distinct, long-lived, posttransitional, follicular B cell populations. Follicular Type I IgMlow B cells require Ag-derived and Btk-dependent signals for their development and make up the majority of cells in the recirculating follicular B cell pool. Follicular type II B cells do not require Btk- or Notch-2-derived signals, make up about a third of the long-lived recirculating B cell pool, and can develop in the absence of Ag. These two follicular populations exhibit differences in basal tyrosine phosphorylation and in BCR-induced proliferation, suggesting that they may represent functionally distinct populations of long-lived recirculating B cells.
Up-Regulation of Bcl-2 through ERK Phosphorylation Is Associated with Human Macrophage Survival in an Estrogen Microenvironment
Authors: Subramanian Manikandan , Shaha Chandrima
Published: April 2014

Estrogen is a known immunomodulator with pleiotropic effects on macrophage function that partly accounts for the gender bias observed in numerous autoimmune, cardiovascular, and neurodegenerative disorders. The effect of estrogen on the survival of human macrophages is largely unknown, and in this study we demonstrate that 17β-estradiol (E2) provokes a death response in human THP-1 macrophages by initiating Bax translocation from cytosol to the mitochondria; however, a concomitant up-regulation of Bcl-2 creates a Bax to Bcl-2 ratio favorable for Bcl-2, thus ensuring cell survival. Both Bcl-2 up-regulation and Bax translocation are estrogen receptor-dependent events; however, Bcl-2 augmentation but not Bax translocation is dependent on Ca2+ increase, activation of protein kinase C, and ERK phosphorylation. This estrogen-induced Bcl-2 increase is crucial for the survival of THP-1 macrophages as well as that of human peripheral blood monocyte-derived macrophages, which is evident from E2-induced cell death under small interfering RNA-mediated Bcl-2 knockdown conditions. Hence, this study demonstrates that E2-induced Bcl-2 up-regulation is a homeostatic survival mechanism necessary for the manifestation of immunomodulatory effect of estrogen on human macrophages.
CTLs Contain and Use Intracellular Stores of FasL Distinct from Cytolytic Granules
Authors: He Jin-Shu , Ostergaard Hanne L.
Published: April 2014

CTL lyse target cells through the release of cytolytic granule contents and cell surface expression of Fas ligand (FasL). Current models suggest that FasL is stored in cytolytic granules and that FasL cell surface expression would be subject to the same controls as degranulation. We demonstrate that murine CTLs undergo two waves of FasL cell surface expression after stimulation. The first wave is from a pre-existing pool of FasL, and the second wave requires new protein synthesis. Signaling for FasL expression appears to be finely tuned as a weak signal preferentially induced surface translocation of the stored FasL, whereas a strong signal preferentially triggered the expression of de novo synthesized FasL. The early FasL is differentially regulated from degranulation, as there were multiple circumstances whereby rapid FasL cell surface expression and FasL-dependent killing occurred in the absence of detectable degranulation. Furthermore, we found through confocal microscopy that stored FasL resides in vesicles distinct from cytolytic granules. Our data clearly show that CTL degranulation and FasL lytic mechanisms are fully independent with respect to stored component localization and regulation.
Induction and Function of Lipocalin Prostaglandin D Synthase in Host Immunity
Authors: Joo Myungsoo , Kwon Minjae , Sadikot Ruxana T. , Kingsley Philip J. , Marnett Lawrence J. , Blackwell Timothy S. , Peebles R. Stokes , Urade Yoshihiro , Christman John W.
Published: April 2014

Although mainly expressed in neuronal cells, lipocalin-type PGD synthase (L-PGDS) is detected in the macrophages infiltrated to atherosclerotic plaques. However, the regulation and significance of L-PGDS expression in macrophages are unknown. Here, we found that treatment of macrophages with bacterial endotoxin (LPS) or Pseudomonas induced L-PGDS expression. Epigenetic suppression of L-PGDS expression in macrophages blunted a majority of PGD2 produced after LPS treatment. Chromatin immunoprecipitation assays show that L-PGDS induction was regulated positively by AP-1, but negatively by p53. L-PGDS expression was detected in whole lung and alveolar macrophages treated with LPS or Pseudomonas. L-PGDS overexpressing transgenic mice improved clearance of Pseudomonas from the lung compared with nontransgenic mice. Similarly, intratracheal instillation of PGD2 enhanced removal of Pseudomonas from the lung in mice. In contrast, L-PGDS knockout mice were impaired in their ability to remove Pseudomonas from the lung. Together, our results identify induction of L-PGDS expression by inflammatory stimuli or bacterial infection, the regulatory mechanism of L-PGDS induction, and the protective role of L-PGDS expression in host immune response. Our study suggests a potential therapeutic usage of L-PGDS or PGD2 against Pseudomonas pneumonia.
Human Blood-Brain Barrier Disruption by Retroviral-Infected Lymphocytes: Role of Myosin Light Chain Kinase in Endothelial Tight-Junction Disorganization
Authors: Afonso Philippe Vicente , Ozden Simona , Prevost Marie-Christine , Schmitt Christine , Seilhean Danielle , Weksler Babette , Couraud Pierre-Olivier , Gessain Antoine , Romero Ignacio Andres , Ceccaldi Pierre-Emmanuel
Published: April 2014

The blood-brain barrier (BBB), which constitutes the interface between blood and cerebral parenchyma, has been shown to be disrupted during retroviral associated neuromyelopathies. Human T cell leukemia virus (HTLV-1)-associated myelopathy/tropical spastic paraparesis is a slowly progressive neurodegenerative disease, in which evidence of BBB breakdown has been demonstrated by the presence of lymphocytic infiltrates in the CNS and plasma protein leakage through cerebral endothelium. Using an in vitro human BBB model, we investigated the cellular and molecular mechanisms involved in endothelial changes induced by HTLV-1-infected lymphocytes. We demonstrate that coculture with infected lymphocytes induces an increase in paracellular endothelial permeability and transcellular migration, via IL-1α and TNF-α secretion. This disruption is associated with tight junction disorganization between endothelial cells, and alterations in the expression pattern of tight junction proteins such as zonula occludens 1. These changes could be prevented by inhibition of the NF-κB pathway or of myosin light chain kinase activity. Such disorganization was confirmed in histological sections of spinal cord from an HTLV-1-associated myelopathy/tropical spastic paraparesis patient. Based on this BBB model, the present data indicate that HTLV-1-infected lymphocytes can induce BBB breakdown and may be responsible for the CNS infiltration that occurs in the early steps of retroviral-associated neuromyelopathies.
Cutting Edge: The IκB Kinase (IKK) Inhibitor, NEMO-Binding Domain Peptide, Blocks Inflammatory Injury in Murine Colitis
Authors: Shibata Wataru , Maeda Shin , Hikiba Yohko , Yanai Ayako , Ohmae Tomoya , Sakamoto Kei , Nakagawa Hayato , Ogura Keiji , Omata Masao
Published: April 2014

Inflammatory mediators such as TNF-α, IL-6, and IL-1 are important in the pathogenesis of inflammatory bowel diseases and are regulated by the activation of NF-κB. The aim of the present study was to investigate whether the NF-κB essential modulator (NEMO)-binding domain (NBD) peptide, which has been shown to block the association of NEMO with the IκB kinaseβ subunit (IKKβ) and inhibit NF-κB activity, reduces inflammatory injury in mice with colitis. Two colitis models were established by the following: 1) inclusion of dextran sulfate sodium salt (DSS) in the drinking water of the mice; and 2) a trinitrobenzene sulfonic acid enema. Marked NF-κB activation and expression of proinflammatory cytokines were observed in colonic tissues. The NBD peptide ameliorated colonic inflammatory injury through the down-regulation of proinflammatory cytokines mediated by NF-κB inhibition in both models. These results indicate that an IKKβ-targeted NF-κB blockade using the NBD peptide could be an attractive therapeutic approach for inflammatory bowel disease.
Cutting Edge: TNF-α-Converting Enzyme (TACE/ADAM17) Inactivation in Mouse Myeloid Cells Prevents Lethality from Endotoxin Shock
Authors: Horiuchi Keisuke , Kimura Tokuhiro , Miyamoto Takeshi , Takaishi Hironari , Okada Yasunori , Toyama Yoshiaki , Blobel Carl P.
Published: April 2014

TNF-α, a potent proinflammatory cytokine, is synthesized as a membrane-anchored precursor and proteolytically released from cells. Soluble TNF is the primary mediator of pathologies such as rheumatoid arthritis, Crohn’s disease, and endotoxin shock. The TNF-α converting enzyme (TACE), a disintegrin and metalloprotease 17 (ADAM17), has emerged as the best candidate TNF sheddase, but other proteinases can also release TNF. Because TACE-deficient mice die shortly after birth, we generated conditional TACE-deficient mice to address whether TACE is the relevant sheddase for TNF in adult mice. In this study, we report that TACE inactivation in myeloid cells or temporal inactivation at 6 wk offers strong protection from endotoxin shock lethality in mice by preventing increased TNF serum levels. These findings corroborate that TACE is the major endotoxin-stimulated TNF sheddase in mouse myeloid cells in vivo, thereby further validating TACE as a principal target for the treatment of TNF-dependent pathologies.
Cutting Edge: Peyer’s Patch Plasmacytoid Dendritic Cells (pDCs) Produce Low Levels of Type I Interferons: Possible Role for IL-10, TGFβ, and Prostaglandin E2 in Conditioning a Unique Mucosal pDC Phenotype
Authors: Contractor Nikhat , Louten Jennifer , Kim Leesun , Biron Christine A. , Kelsall Brian L.
Published: April 2014

The organized lymphoid tissues of the intestine likely play an important role in the balance between tolerance harmless mucosal Ags and commensal bacteria and immunity to mucosal pathogens. We examined the phenotype and function of plasmacytoid dendritic cells (pDCs) from murine Peyer’s patches (PPs). When stimulated with CpG-enriched oligodeoxynucleotides in vitro, PPs and spleen pDCs made equivalent levels of IL-12, yet PP pDCs were incapable of producing significant levels of type I IFNs. Three regulatory factors associated with mucosal tissues, PGE2, IL-10, and TGFβ, inhibited the ability of spleen pDCs to produce type I IFN in a dose-dependent fashion. These studies suggest that mucosal factors may regulate the production of type I IFN as well as IL-12 by pDCs. In the intestine, this may be beneficial in preventing harmful innate and adaptive immune responses to commensal microorganisms.
Cutting Edge: Evidence of Direct TCR α-Chain Interaction with Superantigen
Authors: Pumphrey Nick , Vuidepot Annelise , Jakobsen Bent , Forsberg Göran , Walse Björn , Lindkvist-Petersson Karin
Published: April 2014

Superantigens are known to activate a large number of T cells. The SAg is presented by MHC class II on the APC and its classical feature is that it recognizes the variable region of the β-chain of the TCR. In this article, we report, by direct binding studies, that staphylococcal enterotoxin (SE) H (SEH), a bacterial SAg secreted by Staphylococcus aureus, instead recognizes the variable α-chain (TRAV27) of TCR. Furthermore, we show that different SAgs (e.g., SEH and SEA) can simultaneously bind to one TCR by binding the α-chain and the β-chain, respectively. Theoretical three-dimensional models of the penta complexes are presented. Hence, these findings open up a new dimension of the biology of the staphylococcal enterotoxins.
Antigen Transmission by Replicating Antigen-Bearing Dendritic Cells
Authors: Diao Jun , Winter Erin , Chen Wenhao , Xu Feng , Cattral Mark S.
Published: April 2014

During steady-state conditions, conventional spleen dendritic cells (DC) turn over every 2–3 days. Recent evidence indicates that in situ proliferation of DC arising from immediate conventional DC precursors is an important contributor to their homeostasis. In this study, we report that replication-competent conventional DC precursors and DC can internalize and transfer model particulate and soluble Ags directly to their DC progeny during cell division. Real-time confocal microscopy and flow cytometry indicated that Ag transmission to progeny was symmetrical, and suggested that other mechanisms of inter-DC Ag transfer were not involved. Soluble protein Ags inherited by DC progeny were presented effectively to Ag-specific T lymphocytes. Furthermore, we show that the number of DC, and the proportion that are actively proliferating, expands several-fold during an immune response against a viral infection. Our results point to an unanticipated mechanism in which DC are continuously replaced from Ag-bearing replication-competent precursor cells that pass Ag molecules onto their progeny through successive cell divisions. Our findings help explain how Ag may persist in a population of DC despite the brief lifespan of individual mature DC.
CD8+ T Cell-Mediated Airway Hyperresponsiveness and Inflammation Is Dependent on CD4+IL-4+ T Cells
Authors: Koya Toshiyuki , Miyahara Nobuaki , Takeda Katsuyuki , Matsubara Shigeki , Matsuda Hiroyuki , Swasey Christina , Balhorn Annette , Dakhama Azzeddine , Gelfand Erwin W.
Published: April 2014

CD4+ T cells, particularly Th2 cells, play a pivotal role in allergic airway inflammation. However, the requirements for interactions between CD4+ and CD8+ T cells in airway allergic inflammation have not been delineated. Sensitized and challenged OT-1 mice in which CD8+ T cells expressing the transgene for the OVA257–264 peptide (SIINFEKL) failed to develop airway hyperresponsiveness (AHR), airway eosinophilia, Th2 cytokine elevation, or goblet cell metaplasia. OT-1 mice that received naive CD4+IL-4+ T cells but not CD4+IL-4− T cells before sensitization developed all of these responses to the same degree as wild-type mice. Moreover, recipients of CD4+IL-4+ T cells developed significant increases in the number of CD8+IL-13+ T cells in the lung, whereas sensitized OT-1 mice that received primed CD4+ T cells just before challenge failed to develop these responses. Sensitized CD8-deficient mice that received CD8+ T cells from OT-1 mice that received naive CD4+ T cells before sensitization increased AHR and eosinophil numbers in bronchoalveolar lavage fluid when challenged with allergen. In contrast, sensitized CD8-deficient mice receiving CD8+ T cells from OT-1 mice without CD4+ T cells developed reduced AHR and eosinophil numbers in bronchoalveolar lavage fluid when challenged. These data suggest that interactions between CD4+ and CD8+ T cells, in part through IL-4 during the sensitization phase, are essential to the development of CD8+IL-13+ T cell-dependent AHR and airway allergic inflammation.
Polylactide-Coglycolide Microspheres CoEncapsulating Recombinant Tandem Prion Protein with CpG-Oligonucleotide Break Self-Tolerance to Prion Protein in Wild-Type Mice and Induce CD4 and CD8 T Cell Responses
Authors: Kaiser-Schulz Gunnar , Heit Antje , Quintanilla-Martinez Leticia , Hammerschmidt Franziska , Hess Simone , Jennen Luise , Rezaei Human , Wagner Hermann , Schätzl Hermann M.
Published: April 2014

Prion diseases are fatal neurodegenerative diseases that are characterized by the conformational conversion of the normal, mainly α-helical cellular prion protein (PrP) into the abnormal β-sheet-rich infectious isoform (PrPSc). The immune system neither shows reaction against cellular PrP nor PrPSc, most likely due to profound self-tolerance. In previous studies, we were able to partly overcome self-tolerance using recombinantly expressed dimeric PrP (tandem PrP (tPrP)), in association with different adjuvants. Proof of principle for antiprion efficacy was obtained in vitro and in vivo. In this study, we demonstrate the induction of a specific Th1 T cell response in wild-type mice immunized with tPrP and CpG-oligonucleotide (ODN). Biochemical influences such as refolding conditions, ionic strength, pH, and interaction with CpG-ODN affected antigenic structure and thus improved immunogenicity. Furthermore, s.c. immunization with tPrP and CpG-ODN coencapsulated in biodegradable polylactide-coglycolide microspheres (PLGA-MS) enhanced CD4 T cell responses and, more prominent, the induction of CD8 T cells. In this vaccination protocol, PLGA-MS function as endosomal delivery device of Ag plus CpG-ODN to macrophages and dendritic cells. In contrast, PLGA-MS-based DNA vaccination approaches with a tPrP construct generated poor humoral and T cell responses. Our data show that prophylactic and therapeutic immunization approaches against prion infections might be feasible using tPrP Ag and CpG-ODN adjuvant without detectable side effects.
Tumors Hamper the Immunogenic Competence of CD4+ T Cell-Directed Dendritic Cell Vaccination
Authors: Zimmermann Valérie S. , Casati Anna , Schiering Chris , Caserta Stefano , Hess Michelini Rodrigo , Basso Veronica , Mondino Anna
Published: April 2014

Dendritic cells loaded with tumor-derived peptides induce protective CTL responses and are under evaluation in clinical trails. We report in this study that prophylactic administration of dendritic cells loaded with a MHC class II-restricted peptide derived from a model tumor Ag (Leishmania receptor for activated C kinase (LACK)) confers protection against LACK-expressing TS/A tumors, whereas therapeutic vaccination fails to cure tumor-bearing mice. Although CD4+ T cell-directed dendritic cell vaccination primed effector-like (CD44highCD62Llow, IL-2+, IFN-γ+) and central memory-like lymphocytes (CD44highCD62Lhigh, only IL-2+) in tumor-free mice, this was not the case in tumor-bearing animals in which both priming and persistence of CD4+ T cell memory were suppressed. Suppression was specific for the tumor-associated Ag LACK, and did not depend on CD25+ T cells. Because T cell help is needed for protective immunity, we speculate that the ability of tumors to limit vaccine-induced CD4+ T cell memory could provide a partial explanation for the limited efficacy of current strategies.
Immune Evasion of the Human Pathogen Pseudomonas aeruginosa: Elongation Factor Tuf Is a Factor H and Plasminogen Binding Protein
Authors: Kunert Anja , Losse Josephine , Gruszin Christin , Hühn Michael , Kaendler Kerstin , Mikkat Stefan , Volke Daniela , Hoffmann Ralf , Jokiranta T. Sakari , Seeberger Harald , Moellmann Ute , Hellwage Jens , Zipfel Peter F.
Published: April 2014

Pseudomonas aeruginosa is an opportunistic human pathogen that can cause a wide range of clinical symptoms and infections that are frequent in immunocompromised patients. In this study, we show that P. aeruginosa evades human complement attack by binding the human plasma regulators Factor H and Factor H-related protein-1 (FHR-1) to its surface. Factor H binds to intact bacteria via two sites that are located within short consensus repeat (SCR) domains 6–7 and 19–20, and FHR-1 binds within SCR domain 3–5. A P. aeruginosa Factor H binding protein was isolated using a Factor H affinity matrix, and was identified by mass spectrometry as the elongation factor Tuf. Factor H uses the same domains for binding to recombinant Tuf and to intact bacteria. Factor H bound to recombinant Tuf displayed cofactor activity for degradation of C3b. Similarly Factor H bound to intact P. aeruginosa showed complement regulatory activity and mediated C3b degradation. This acquired complement control was rather effective and acted in concert with endogenous proteases. Immunolocalization identified Tuf as a surface protein of P. aeruginosa. Tuf also bound plasminogen, and Tuf-bound plasminogen was converted by urokinase plasminogen activator to active plasmin. Thus, at the bacterial surface Tuf acts as a virulence factor and binds the human complement regulator Factor H and plasminogen. Acquisition of host effector proteins to the surface of the pathogen allows complement control and may facilitate tissue invasion.
Acute Loss of Intestinal CD4+ T Cells Is Not Predictive of Simian Immunodeficiency Virus Virulence
Authors: Pandrea Ivona V. , Gautam Rajeev , Ribeiro Ruy M. , Brenchley Jason M. , Butler Isolde F. , Pattison Melissa , Rasmussen Terri , Marx Preston A. , Silvestri Guido , Lackner Andrew A. , Perelson Alan S. , Douek Daniel C. , Veazey Ronald S. , Apetrei Cristian
Published: April 2014

The predictive value of acute gut-associated lymphoid tissue (GALT) CD4+ T cell depletion in lentiviral infections was assessed by comparing three animal models illustrative of the outcomes of SIV infection: pathogenic infection (SIVsmm infection of rhesus macaques (Rh)), persistent nonprogressive infection (SIVagm infection of African green monkeys (AGM)), and transient, controlled infection (SIVagm infection of Rh). Massive acute depletion of GALT CD4+ T cells was a common feature of acute SIV infection in all three models. The outcome of this mucosal CD4+ T cell depletion, however, differed substantially between the three models: in SIVsmm-infected Rh, the acute GALT CD4+ T cell depletion was persistent and continued with disease progression; in SIVagm, intestinal CD4+ T cells were partially restored during chronic infection in the context of normal levels of apoptosis and immune activation and absence of damage to the mucosal immunologic barrier; in SIVagm-infected Rh, complete control of viral replication resulted in restoration of the mucosal barrier and immune restoration. Therefore, our data support a revised paradigm wherein severe GALT CD4+ T cell depletion during acute pathogenic HIV and SIV infections of humans and Rh is necessary but neither sufficient nor predictive of disease progression, with levels of immune activation, proliferation and apoptosis being key factors involved in determining progression to AIDS.
Virally Induced CD4+ T Cell Depletion Is Not Sufficient to Induce AIDS in a Natural Host
Authors: Milush Jeffrey M. , Reeves Jacqueline D. , Gordon Shari N. , Zhou Dejiang , Muthukumar Alagar , Kosub David A. , Chacko Elizabeth , Giavedoni Luis D. , Ibegbu Chris C. , Cole Kelly S. , Miamidian John L. , Paiardini Mirko , Barry Ashley P. , Staprans Silvija I. , Silvestri Guido , Sodora Donald L.
Published: April 2014

Peripheral blood CD4+ T cell counts are a key measure for assessing disease progression and need for antiretroviral therapy in HIV-infected patients. More recently, studies have demonstrated a dramatic depletion of mucosal CD4+ T cells during acute infection that is maintained during chronic pathogenic HIV as well as SIV infection. A different clinical disease course is observed during the infection of natural hosts of SIV infection, such as sooty mangabeys (Cercocebus atys), which typically do not progress to AIDS. Previous studies have determined that SIV+ mangabeys generally maintain healthy levels of CD4+ T cells despite having viral replication comparable to HIV-infected patients. In this study, we identify the emergence of a multitropic (R5/X4/R8-using) SIV infection after 43 or 71 wk postinfection in two mangabeys that is associated with an extreme, persistent (>5.5 years), and generalized loss of CD4+ T cells (5–80 cells/μl of blood) in the absence of clinical signs of AIDS. This study demonstrates that generalized CD4+ T cell depletion from the blood and mucosal tissues is not sufficient to induce AIDS in this natural host species. Rather, AIDS pathogenesis appears to be the cumulative result of multiple aberrant immunologic parameters that include CD4+ T cell depletion, generalized immune activation, and depletion/dysfunction of non-CD4+ T cells. Therefore, these data provide a rationale for investigating multifaceted therapeutic strategies to prevent progression to AIDS, even following dramatic CD4 depletion, such that HIV+ humans can survive normal life spans analogous to what occurs naturally in SIV+ mangabeys.
Central Memory Vγ9Vδ2 T Lymphocytes Primed and Expanded by Bacillus Calmette-Guérin-Infected Dendritic Cells Kill Mycobacterial-Infected Monocytes
Authors: Martino Angelo , Casetti Rita , Sacchi Alessandra , Poccia Fabrizio
Published: April 2014

In humans, innate immune recognition of mycobacteria, including Mycobacterium tuberculosis and bacillus Calmette-Guérin (BCG), is a feature of cells as dendritic cells (DC) and γδ T cells. In this study, we show that BCG infection of human monocyte-derived DC induces a rapid activation of Vγ9Vδ2 T cells (the major subset of γδ T cell pool in human peripheral blood). Indeed, in the presence of BCG-infected DC, Vγ9Vδ2 T cells increase both their expression of CD69 and CD25 and the production of TNF-α and IFN-γ, in contrast to DC treated with Vγ9Vδ2 T cell-specific Ags. Without further exogenous stimuli, BCG-infected DC expand a functionally cytotoxic central memory Vγ9Vδ2 T cell population. This subset does not display lymph node homing receptors, but express a high amount of perforin. They are highly efficient in the killing of mycobacterial-infected primary monocytes or human monocytic THP-1 cells preserving the viability of cocultured, infected DC. This study provides further evidences about the complex relationship between important players of innate immunity and suggests an immunoregulatory role of Vγ9Vδ2 T cells in the control of mycobacterial infection.
The Paneth Cell α-Defensin Deficiency of Ileal Crohn’s Disease Is Linked to Wnt/Tcf-4
Authors: Wehkamp Jan , Wang Guoxing , Kübler Irmgard , Nuding Sabine , Gregorieff Alex , Schnabel Anke , Kays Robert J. , Fellermann Klaus , Burk Oliver , Schwab Matthias , Clevers Hans , Bevins Charles L. , Stange Eduard F.
Published: April 2014

Ileal Crohn′s disease (CD), a chronic mucosal inflammation, is characterized by two pertinent features: a specific decrease of Paneth cell-produced antimicrobial α-defensins and the presence of mucosal-adherent bacteria. A mutation in NOD2, the muramyl dipeptide recognition receptor, is found in some patients, which leads to an even more pronounced α-defensin decrease. However, the underlying mechanism remains unclear for the majority of patients. In this study, we report a reduced expression in ileal CD of the Wnt-signaling pathway transcription factor Tcf-4, a known regulator of Paneth cell differentiation and α-defensin expression. Within specimens, the levels of Tcf-4 mRNA showed a high degree of correlation with both HD5 and HD6 mRNA. The levels of Tcf-4 mRNA were decreased in patients with ileal disease irrespective of degree of inflammation, but were not decreased in colonic CD or ulcerative colitis. As a functional indicator of Tcf-4 protein, quantitative binding analysis with nuclear extracts from small intestine biopsies to a Tcf-4 high-affinity binding site in the HD-5 and HD-6 promoters showed significantly reduced activity in ileal CD. Furthermore, a causal link was shown in a murine Tcf-4 knockout model, where the comparably reduced expression of Tcf-4 in heterozygous (+/−) mice was sufficient to cause a significant decrease of both Paneth cell α-defensin levels and bacterial killing activity. Finally, the association between Paneth cell α-defensins and Tcf-4 was found to be independent of the NOD2 genotype. This new link established between a human inflammatory bowel disease and the Wnt pathway/Tcf-4 provides a novel mechanism for pathogenesis in patients with ileal CD.
Inhibition of HIV-1 Infectivity and Epithelial Cell Transfer by Human Monoclonal IgG and IgA Antibodies Carrying the b12 V Region
Authors: Mantis Nicholas J. , Palaia Jana , Hessell Ann J. , Mehta Simren , Zhu Zhiyi , Corthésy Blaise , Neutra Marian R. , Burton Dennis R. , Janoff Edward N.
Published: April 2014

Both IgG and secretory IgA Abs in mucosal secretions have been implicated in blocking the earliest events in HIV-1 transit across epithelial barriers, although the mechanisms by which this occurs remain largely unknown. In this study, we report the production and characterization of a human rIgA2 mAb that carries the V regions of IgG1 b12, a potent and broadly neutralizing anti-gp120 Ab which has been shown to protect macaques against vaginal simian/HIV challenge. Monomeric, dimeric, polymeric, and secretory IgA2 derivatives of b12 reacted with gp120 and neutralized CCR5- and CXCR4-tropic strains of HIV-1 in vitro. With respect to the protective effects of these Abs at mucosal surfaces, we demonstrated that IgG1 b12 and IgA2 b12 inhibited the transfer of cell-free HIV-1 from ME-180 cells, a human cervical epithelial cell line, as well as Caco-2 cells, a human colonic epithelial cell line, to human PBMCs. Inhibition of viral transfer was due to the ability of b12 to block both viral attachment to and uptake by epithelial cells. These data demonstrate that IgG and IgA MAbs directed against a highly conserved epitope on gp120 can interfere with the earliest steps in HIV-1 transmission across mucosal surfaces, and reveal a possible mechanism by which b12 protects the vaginal mucosal against viral challenge in vivo.
Codominance of TLR2-Dependent and TLR2-Independent Modulation of MHC Class II inMycobacterium tuberculosisInfection In Vivo
Authors: Kincaid Eleanor Z. , Wolf Andrea J. , Desvignes Ludovic , Mahapatra Sebabrata , Crick Dean C. , Brennan Patrick J. , Pavelka Martin S. , Ernst Joel D.
Published: April 2014

Mycobacterium tuberculosis is an exceptionally successful human pathogen. A major component of this success is the ability of the bacteria to infect immunocompetent individuals and to evade eradication by an adaptive immune response that includes production of the macrophage-activating cytokine, IFN-γ. Although IFN-γ is essential for arrest of progressive tuberculosis, it is insufficient for efficacious macrophage killing of the bacteria, which may be due to the ability of M. tuberculosis to inhibit selected macrophage responses to IFN-γ. In vitro studies have determined that mycobacterial lipoproteins and other components of the M. tuberculosis cell envelope, acting as agonists for TLR2, inhibit IFN-γ induction of MHC class II. In addition, M. tuberculosis peptidoglycan and IL-6 secreted by infected macrophages inhibit IFN-γ induction of MHC class II in a TLR2-independent manner. To determine whether TLR2-dependent inhibition of macrophage responses to IFN-γ is quantitatively dominant over the TLR2-independent mechanisms in vivo, we prepared mixed bone marrow chimeric mice in which the hemopoietic compartment was reconstituted with a mixture of TLR+/+ and TLR2−/− cells. When the chimeric mice were infected with M. tuberculosis, the expression of MHC class II on TLR2+/+ and TLR2−/− macrophages from the lungs of individual infected chimeric mice was indistinguishable. These results indicate that TLR2-dependent and -independent mechanisms of inhibition of responses to IFN-γ are equivalent in vivo, and that M. tuberculosis uses multiple pathways to abrogate the action of an important effector of adaptive immunity.
Individual Variation of Scavenger Receptor Expression in Human Macrophages with Oxidized Low-Density Lipoprotein Is Associated with a Differential Inflammatory Response
Authors: Martín-Fuentes Paula , Civeira Fernando , Recalde Delia , García-Otín Angel Luis , Jarauta Estíbaliz , Marzo Isabel , Cenarro Ana
Published: April 2014

Atherosclerosis is an inflammatory disease in which oxidized low-density lipoprotein (oxLDL) plays important roles. Scavenger receptors (SR) CD36, SR-A, and LOX-1 uptake over 90% of the oxLDL leading to foam cell formation and secretion of inflammatory cytokines. To investigate whether the interindividual differences in macrophage SR gene expression could determine the inflammatory variability in response to oxLDL, we quantified the gene and protein expression of SR and inflammatory molecules from macrophages isolated from 18 volunteer subjects and incubated with oxLDL for 1, 3, 6, and 18 h. The individual gene expression profile of the studied SR at 1 h of incubation was highly variable, showing a wide fold-change range: CD36: −3.57–4.22, SR-A: −5.0–4.43, and LOX-1: −1.56–75.32. We identified subjects as high and low responders depending on whether their SR gene expression was above or below the median, showing a different inflammation response pattern. CD36 and LOX-1 gene expression correlated positively with IL-1β; SR-A correlated negatively with IL-8 and positively with PPARγ and NF-κBΙA. These results were confirmed in the same subjects 3 mo after the first sampling. Furthermore, a negative correlation existed between CD36 and SR-A at protein level after 18 h of oxLDL incubation (R = −0.926, p = 0.024). These data would suggest that the type of SR could determine the macrophage activation: more proinflammatory when associated to CD36 and LOX-1 than when associated with SR-A.
Th2 Differentiation in Distinct Lymph Nodes Influences the Site of Mucosal Th2 Immune-Inflammatory Responses
Authors: Alvarez David , Arkinson Janine L. , Sun Jiangfeng , Fattouh Ramzi , Walker Tina , Jordana Manel
Published: April 2014

Allergic individuals rarely present with concurrent multiple-organ disease but, rather, with manifestations that privilege a specific site such as the lung, skin, or gastrointestinal tract. Whether the site of allergic sensitization influences the localization of Th2 immune-inflammatory responses and, ultimately, the organ-specific expression of disease, remains to be determined. In this study, we investigated whether both the site of initial Ag exposure and concomitant Th2 differentiation in specific lymph nodes (LNs) privileges Th2 memory responses to mucosal and nonmucosal sites, and whether this restriction is associated with a differential expression in tissue-specific homing molecules. In mice exposed to Ag (OVA) via the peritoneum, lung, or skin, we examined several local and distal LNs to determine the site of Ag-specific proliferation and Th2 differentiation. Whereas respiratory and cutaneous Ag exposure led to Ag-specific proliferation and Th2 differentiation exclusively in lung- and skin-draining LNs, respectively, Ag delivery to the peritoneum evoked responses in gut-associated, as well as distal thoracic, LNs. Importantly, only mice that underwent Th2 differentiation in thoracic- or gut-associated LNs mounted Th2 immune-inflammatory responses upon respiratory or gastric Ag challenge, respectively, whereas cutaneous Th2 recall responses were evoked irrespective of the site of initial sensitization. In addition, we observed the differential expression of gut homing molecules (CCR9, α4, β7) in gut-associated LNs and, unexpectedly, a universal induction of skin-related homing molecules (CCR4, CCR10) in all LNs. These data suggest that the site of initial Th2 differentiation and differential homing molecule expression restricts Th2 immune-inflammatory responses to mucosal, but not cutaneous, tissues.
CD4+ T Cells Generated De Novo from Donor Hemopoietic Stem Cells Mediate the Evolution from Acute to Chronic Graft-versus-Host Disease
Authors: Zhang Yi , Hexner Elizabeth , Frank Dale , Emerson Stephen G.
Published: April 2014

Acute and chronic graft-versus-host disease (GVHD) remain the major complications limiting the efficacy of allogeneic hemopoietic stem cell transplantation. Chronic GVHD can evolve from acute GVHD, or in some cases may overlap with acute GVHD, but how acute GVHD evolves to chronic GVHD is unknown. In this study, in a classical CD8+ T cell-dependent mouse model, we found that pathogenic donor CD4+ T cells developed from engrafted hemopoietic stem cells (HSCs) in C57BL/6SJL(B6/SJL, H-2b) mice suffering from acute GVHD after receiving donor CD8+ T cells and HSCs from C3H.SW mice (H-2b). These CD4+ T cells were activated, infiltrated into GVHD target tissues, and produced high levels of IFN-γ. These in vivo-generated CD4+ T cells caused lesions characteristic of chronic GVHD when adoptively transferred into secondary allogeneic recipients and also caused GVHD when administered into autologous C3H.SW recipients. The in vivo generation of pathogenic CD4+ T cells from engrafted donor HSCs was thymopoiesis dependent. Keratinocyte growth factor treatment improved the reconstitution of recipient thymic dendritic cells in CD8+ T cell-repleted allogeneic hemopoietic stem cell transplantation and prevented the development of pathogenic donor CD4+ T cells. These results suggest that de novo-generated donor CD4+ T cells, arising during acute graft-versus-host reactions, are key contributors to the evolution from acute to chronic GVHD. Preventing or limiting thymic damage may directly ameliorate chronic GVHD.
Peripheral Tolerance and the Qualitative Characteristics of Autoreactive T Cell Clones in Primary Biliary Cirrhosis
Authors: Kawano Akira , Shimoda Shinji , Kamihira Takashi , Ishikawa Fumihiko , Niiro Hiroaki , Soejima Yuji , Taketomi Akinobu , Maehara Yoshihiko , Nakamura Minoru , Komori Atsumasa , Migita Kiyoshi , Ishibashi Hiromi , Azuma Miyuki , Gershwin M. Eric , Harada Mine
Published: April 2014

Primary biliary cirrhosis is characterized by autoreactive T cells specific for the mitochondrial Ag PDC-E2163–176. We studied the ability of eight T cell clones (TCC) specific for PDC-E2163–176 to proliferate or become anergic in the presence of costimulation signals. TCC were stimulated with either human PDC-E2163–176, an Escherichia coli 2-oxoglutarate dehydrogenase mimic (OGDC-E234–47), or analogs with amino acid substitutions using HLA-matched allogeneic PBMC or mouse L-DR53 fibroblasts as APC. Based on their differential responses to these peptides (human PDC-E2163–176, E. coli OGDC-E234–47) in the different APC systems, TCC were classified as costimulation dependent or independent. Only costimulation-dependent TCC could become anergic. TCC with costimulation-dependent responses to OGDC-E2 become anergic to PDC-E2 when preincubated with mimic, even if costimulation is independent for PDC-E2163–176. Anergic TCC produced IL-10. One selected TCC could not become anergic after preincubation with PDC-E2163–176-pulsed L-DR53 but became anergic using L-DR53 pulsed with PDC-E2 peptide analogs with a substitution at a critical TCR binding site. TCC that only respond to peptide-pulsed PBMC, but not L-DR53, proliferate with peptide-pulsed CD80/CD86-transfected L-DR53; however, anergy was not induced with peptide-pulsed L-DR53 transfected with only CD80 or CD86. These data highlight that costimulation plays a dominant role in maintaining peripheral tolerance to PBC-specific Ags. They further suggest that, under specific circumstances, molecular mimicry of an autoantigen may restore rather than break peripheral tolerance.
Tumor-Derived Chemokine MCP-1/CCL2 Is Sufficient for Mediating Tumor Tropism of Adoptively Transferred T Cells
Authors: Brown Christine E. , Vishwanath Reena P. , Aguilar Brenda , Starr Renate , Najbauer Joseph , Aboody Karen S. , Jensen Michael C.
Published: April 2014

To exert a therapeutic effect, adoptively transferred tumor-specific CTLs must traffic to sites of tumor burden, exit the circulation, and infiltrate the tumor microenvironment. In this study, we examine the ability of adoptively transferred human CTL to traffic to tumors with disparate chemokine secretion profiles independent of tumor Ag recognition. Using a combination of in vivo tumor tropism studies and in vitro biophotonic chemotaxis assays, we observed that cell lines derived from glioma, medulloblastoma, and renal cell carcinoma efficiently chemoattracted ex vivo-expanded primary human T cells. We compared the chemokines secreted by tumor cell lines with high chemotactic activity with those that failed to elicit T cell chemotaxis (Daudi lymphoma, 10HTB neuroblastoma, and A2058 melanoma cells) and found a correlation between tumor-derived production of MCP-1/CCL2 (≥10 ng/ml) and T cell chemotaxis. Chemokine immunodepletion studies confirmed that tumor-derived MCP-1 elicits effector T cell chemotaxis. Moreover, MCP-1 is sufficient for in vivo T cell tumor tropism as evidenced by the selective accumulation of i.v. administered firefly luciferase-expressing T cells in intracerebral xenografts of tumor transfectants secreting MCP-1. These studies suggest that the capacity of adoptively transferred T cells to home to tumors may be, in part, dictated by the species and amounts of tumor-derived chemokines, in particular MCP-1.
B Subunit of Shiga Toxin-Based Vaccines Synergize with α-Galactosylceramide to Break Tolerance against Self Antigen and Elicit Antiviral Immunity
Authors: Adotevi Olivier , Vingert Benoit , Freyburger Ludovic , Shrikant Protul , Lone Yu-Chun , Quintin-Colonna Françoise , Haicheur Nacilla , Amessou Mohamed , Herbelin André , Langlade-Demoyen Pierre , Fridman Wolf H. , Lemonnier François , Johannes Ludger , Tartour Eric
Published: April 2014

The nontoxic B subunit of Shiga toxin (STxB) targets in vivo Ag to dendritic cells that preferentially express the glycolipid Gb3 receptor. After administration of STxB chemically coupled to OVA (STxB-OVA) or E7, a polypeptide derived from HPV, in mice, we showed that the addition of α-galactosylceramide (α-GalCer) resulted in a dramatic improvement of the STxB Ag delivery system, as reflected by the more powerful and longer lasting CD8+ T cell response observed even at very low dose of immunogen (50 ng). This synergy was not found with other adjuvants (CpG, poly(I:C), IFN-α) also known to promote dendritic cell maturation. With respect to the possible mechanism explaining this synergy, mice immunized with α-GalCer presented in vivo the OVA257–264/Kb complex more significantly and for longer period than mice vaccinated with STxB alone or mixed with other adjuvants. To test whether this vaccine could break tolerance against self Ag, OVA transgenic mice were immunized with STxB-OVA alone or mixed with α-GalCer. Although no CTL induction was observed after immunization of OVA transgenic mice with STxB-OVA, tetramer assay clearly detected specific anti-OVA CD8+ T cells in 8 of 11 mice immunized with STxB-OVA combined with α-GalCer. In addition, vaccination with STxB-OVA and α-GalCer conferred strong protection against a challenge with vaccinia virus encoding OVA with virus titers in the ovaries reduced by 5 log compared with nonimmunized mice. STxB combined with α-GalCer therefore appears as a promising vaccine strategy to more successfully establish protective CD8+ T cell memory against intracellular pathogens and tumors.