bluuebunny/crossref_metadata_2025 huggingface dataset:
Distinct Effector Mechanisms in the Development of Autoimmune Neuropathy versus Diabetes in Nonobese Diabetic Mice
Authors: Bour-Jordan Hélène , Thompson Heather L. , Bluestone Jeffrey A.
Published: April 2014

NOD mice deficient for the costimulatory molecule B7-2 (NOD-B7-2KO mice) are protected from autoimmune diabetes but develop a spontaneous autoimmune peripheral neuropathy that resembles human diseases Guillain-Barre syndrome and chronic inflammatory demyelinating polyradiculoneuropathy. Similar observations have now been made in conventional NOD mice. We have shown previously that this disease was mediated by autoreactive T cells inducing demyelination in the peripheral nervous system. In this study, we analyzed the molecular pathways involved in the disease. Our data showed that neuropathy developed in the absence of perforin or fas, suggesting that classic cytotoxicity pathways were dispensable for nerve damage in NOD-B7-2KO mice. In contrast, IFN-γ played an obligatory role in the development of neuropathy as demonstrated by the complete protection from disease and infiltration in the nerves in NOD-B7-2KO mice deficient for IFN-γ. This result was consistent with the inflammatory phenotype of T cells infiltrating the peripheral nerves. Importantly, the relative role of perforin, fas, and IFN-γ appears completely different in autoimmune diabetes vs neuropathy. Thus, there are sharp contrasts in the pathogenesis of autoimmune diseases targeting different tissues in the same NOD background.
TGF-β1 Inhibits T-bet Induction by IFN-γ in Murine CD4+ T Cells through the Protein Tyrosine Phosphatase Src Homology Region 2 Domain-Containing Phosphatase-1
Authors: Park Il-Kyoo , Shultz Leonard D. , Letterio John J. , Gorham James D.
Published: April 2014

TGF-β1 prevents the development of autoimmune disease by restraining the development of autoreactive Th1 cells. TGF-β1 inhibits Th1 development in part by suppressing the expression of T-bet, an IFN-γ-induced transcription factor that promotes Th1 differentiation, but how TGF-β1 suppresses T-bet is not known. In this study we show that TGF-β1 suppresses IFN-γ-induced T-bet expression through the hemopoietic protein tyrosine phosphatase (PTP) Src homology region 2 domain-containing phosphatase-1 (Shp-1). In murine CD4+ T cells, IFN-γ rapidly induced the expression of T-bet as well as of IFN regulatory factor-1, another transcription factor important for Th1 development. TGF-β1 antagonized the effects of IFN-γ, inhibiting IFN-γ’s induction of both Th1 transcription factors. In the presence of IFN-γ, TGF-β1 rapidly induced in Th cells the synthesis of the PTP Shp-1, but did not induce Shp-2 or several members of the suppressor of cytokine signaling family of Jak-Stat inhibitors. We tested the requirement for Shp-1 by using T cells from the Shp-1-deficient mev/mev mouse strain. Shp-1 was required for TGF-β1’s suppressive effects, because its suppression of T-bet and IFN regulatory factor-1 was completely abrogated in mev/mev CD4+ T cells. Receptor-proximal responses to IFN-γ, such as the induction of Jak-Stat phosphorylation, were inhibited by TGF-β1 in wild-type T cells, but not in mev/mev T cells. Consistent with a direct role for Shp-1, TGF-β1’s inhibition of IFN-γ-induced Stat1 phosphorylation was sensitive to the general PTP inhibitor pervanadate. Together, these data show that TGF-β1 suppresses IFN-γ signaling and transcriptional responses in CD4+ T cells through the PTP Shp-1.
Molecular Signature of Recent Thymic Selection Events on Effector and Regulatory CD4+ T Lymphocytes
Authors: Romagnoli Paola , Hudrisier Denis , van Meerwijk Joost P. M.
Published: April 2014

Natural CD4+CD25+ regulatory T lymphocytes (Treg) are key protagonists in the induction and maintenance of peripheral T cell tolerance. Their thymic origin and biased repertoire continue to raise important questions about the signals that mediate their development. We validated analysis of MHC class II capture by developing thymocytes from thymic stroma as a tool to study quantitative and qualitative aspects of the cellular interactions involved in thymic T cell development and used it to analyze Treg differentiation in wild-type mice. Our data indicate that APCs of bone marrow origin, but, surprisingly and importantly, not thymic epithelial cells, induce significant negative selection among the very autoreactive Treg precursors. This fundamental difference between thymic development of regulatory and effector T lymphocytes leads to the development of a Treg repertoire enriched in cells specific for a selected subpopulation of self-Ags, i.e., those specifically expressed by thymic epithelial cells.
Promiscuous Thymic Expression of an Autoantigen Gene Does Not Result in Negative Selection of Pathogenic T Cells
Authors: Allen Stacey , Read Simon , DiPaolo Richard , McHugh Rebecca S. , Shevach Ethan M. , Gleeson Paul A. , van Driel Ian R.
Published: April 2014

“Promiscuous” thymic expression of peripheral autoantigens can contribute to immunological tolerance in some cases. However, in this study we show that thymic mRNA expression alone cannot predict a contribution to thymic tolerance. Autoimmune gastritis is caused by CD4+ T cells directed to the α (H/Kα) and β (H/Kβ) subunits of the gastric membrane protein the H+/K+ ATPase. H/Kα mRNA is expressed in the thymus, but H/Kβ expression is barely detectable. In this study, we demonstrate that thymic H/Kα in wild-type mice or mice that overexpressed H/Kα did not result in negative selection of pathogenic anti-H/Kα T cells. However, negative selection of anti-H/Kα T cells did occur if H/Kβ was artificially overexpressed in the thymus. Given that H/Kα cannot be exported from the endoplasmic reticulum and is rapidly degraded in the absence of H/Kβ, we conclude that H/Kα epitopes are unable to access MHC class II loading compartments in cells of the normal thymus. This work, taken together with our previous studies, highlights that thymic autoantigen expression does not necessarily result in the induction of tolerance.
Inhibition of Histone Deacetylase Suppresses Osteoclastogenesis and Bone Destruction by Inducing IFN-β Production
Authors: Nakamura Takahiro , Kukita Toshio , Shobuike Takeo , Nagata Kengo , Wu Zhou , Ogawa Kenji , Hotokebuchi Takao , Kohashi Osamu , Kukita Akiko
Published: April 2014

Osteoclasts are bone-resorptive multinucleated cells that are differentiated from hemopoietic cell lineages of monocyte/macrophages in the presence of receptor activator of NF-κB ligand (RANKL) and M-CSF. Downstream signaling molecules of the receptor of RANKL, RANK, modulate the differentiation and the activation of osteoclasts. We recently found that histone deacetylase inhibitors (HDIs), known as anticancer agents, selectively suppressed osteoclastogenesis in vitro. However, the molecular mechanism underlying inhibitory action of HDIs in osteoclastogenesis and the effect of HDIs on pathological bone destruction are still not remained to be elucidated. In this study, we show that a depsipeptide, FR901228, inhibited osteoclast differentiation by not only suppressing RANKL-induced nuclear translocation of NFATc1 but also increasing the mRNA level of IFN-β, an inhibitor of osteoclastogenesis. The inhibition of osteoclast formation by FR901228 was abrogated by the addition of IFN-β-neutralizing Ab. In addition, treatment of adjuvant-induced arthritis in rats revealed that FR901228 inhibited not only disease development in a prophylactic model but also bone destruction in a therapeutic model. Furthermore, immunostaining of the joints of therapeutically treated rats revealed significant production of IFN-β in synovial cells. Taken together, these data suggest that a HDI inhibits osteoclastogenesis and bone destruction by a novel action to induce the expression of osteoclast inhibitory protein, IFN-β.
CD4 T Cell-Independent Antibody Response Promotes Resolution of Primary Influenza Infection and Helps to Prevent Reinfection
Authors: Lee Byung O. , Rangel-Moreno Javier , Moyron-Quiroz Juan E. , Hartson Louise , Makris Melissa , Sprague Frank , Lund Frances E. , Randall Troy D.
Published: April 2014

It is generally believed that the production of influenza-specific IgG in response to viral infection is dependent on CD4 T cells. However, we previously observed that CD40-deficient mice generate influenza-specific IgG during a primary infection, suggesting that influenza infection may elicit IgG responses independently of CD4 T cell help. In the present study, we tested this hypothesis and show that mice lacking CD40 or CD4 T cells produce detectable titers of influenza-specific IgG and recover from influenza infection in a manner similar to that of normal mice. In contrast, mice completely lacking B cells succumb to influenza infection, despite the presence of large numbers of functional influenza-specific CD8 effector cells in the lungs. Consistent with the characteristics of a T-independent Ab response, long-lived influenza-specific plasma cells are not found in the bone marrow of CD40−/− and class II−/− mice, and influenza-specific IgG titers wane within 60 days postinfection. However, despite the short-lived IgG response, CD40−/− and class II−/− mice are completely protected from challenge infection with the same virus administered within 30 days. This protection is mediated primarily by B cells and Ab, as influenza-immune CD40−/− and class II−/− mice were still resistant to challenge infection when T cells were depleted. These data demonstrate that T cell-independent influenza-specific Ab promotes the resolution of primary influenza infection and helps to prevent reinfection.
A Defect in Deletion of Nucleosome-Specific Autoimmune T Cells in Lupus-Prone Thymus: Role of Thymic Dendritic Cells
Authors: Michaels Marissa A. , Kang Hee-Kap , Kaliyaperumal Arunan , Satyaraj Ebenezar , Shi Yan , Datta Syamal K.
Published: April 2014

To study central tolerance to the major product of ongoing apoptosis in the thymus, we made new lines of transgenic (Tg) mice expressing TCR of a pathogenic autoantibody-inducing Th cell that was specific for nucleosomes and its histone peptide H471–94. In the lupus-prone (SWR × NZB)F1 (SNF1) thymus, introduction of the lupus TCR transgene caused no deletion, but marked down-regulation of the Tg TCR and up-regulation of endogenous TCRs. Paradoxically, autoimmune disease was suppressed in the αβTCR Tg SNF1 mice with induction of highly potent regulatory T cells in the periphery. By contrast, in the MHC-matched, normal (SWR × B10. D2)F1 (SBF1), or in the normal SWR backgrounds, marked deletion of transgenic thymocytes occurred. Thymic lymphoid cells of the normal or lupus-prone mice were equally susceptible to deletion by anti-CD3 Ab or irradiation. However, in the steady state, spontaneous presentation of naturally processed peptides related to the nucleosomal autoepitope was markedly greater by thymic dendritic cells (DC) from normal mice than that from lupus mice. Unmanipulated thymic DC of SNF1 mice expressed lesser amounts of MHC class II and costimulatory molecules than their normal counterparts. These results indicate that apoptotic nucleosomal autoepitopes are naturally processed and presented to developing thymocytes, and a relative deficiency in the natural display of nucleosomal autoepitopes by thymic DC occurs in lupus-prone SNF1 mice.
Ig Gene Rearrangement Steps Are Initiated in Early Human Precursor B Cell Subsets and Correlate with Specific Transcription Factor Expression
Authors: van Zelm Menno C. , van der Burg Mirjam , de Ridder Dick , Barendregt Barbara H. , de Haas Edwin F. E. , Reinders Marcel J. T. , Lankester Arjan C. , Révész Tom , Staal Frank J. T. , van Dongen Jacques J. M.
Published: April 2014

The role of specific transcription factors in the initiation and regulation of Ig gene rearrangements has been studied extensively in mouse models, but data on normal human precursor B cell differentiation are limited. We purified five human precursor B cell subsets, and assessed and quantified their IGH, IGK, and IGL gene rearrangement patterns and gene expression profiles. Pro-B cells already massively initiate DH-JH rearrangements, which are completed with VH-DJH rearrangements in pre-B-I cells. Large cycling pre-B-II cells are selected for in-frame IGH gene rearrangements. The first IGK/IGL gene rearrangements were initiated in pre-B-I cells, but their frequency increased enormously in small pre-B-II cells, and in-frame selection was found in immature B cells. Transcripts of the RAG1 and RAG2 genes and earlier defined transcription factors, such as E2A, early B cell factor, E2-2, PAX5, and IRF4, were specifically up-regulated at stages undergoing Ig gene rearrangements. Based on the combined Ig gene rearrangement status and gene expression profiles of consecutive precursor B cell subsets, we identified 16 candidate genes involved in initiation and/or regulation of Ig gene rearrangements. These analyses provide new insights into early human precursor B cell differentiation steps and represent an excellent template for studies on oncogenic transformation in precursor B acute lymphoblastic leukemia and B cell differentiation blocks in primary Ab deficiencies.
Dendritic Cell Maturation, but Not CD8+ T Cell Induction, Is Dependent on Type I IFN Signaling during Vaccination with Adenovirus Vectors
Authors: Hensley Scott E. , Giles-Davis Wynetta , McCoy Kimberly C. , Weninger Wolfgang , Ertl Hildegund C. J.
Published: April 2014

To understand how vaccines initiate adaptive immune responses, it is necessary to study how they interact with APCs such as dendritic cells (DCs). In this study, we analyzed interactions between recombinant adenovirus (Ad) vectors and mouse DCs. Mouse bone marrow-derived DCs transduced with Ad vectors produced type I IFN, which promoted the maturation of both transduced and bystander DCs. DCs transduced with a vector derived from a chimpanzee Ad serotype (AdC68) produced more type I IFN and matured more efficiently compared with DCs transduced with a vector derived from a human Ad serotype (AdHu5). Both vectors stimulated type I IFN production independently of viral transcription, replication, and TLR signaling. However, each vector induced type I IFN through distinct pathways; whereas AdHu5 vectors required phosphoinositide-3-OH kinase for type I IFN induction, AdC68 vectors did not. Both vectors induced strong transgene product-specific CD8+ T cell responses in wild-type mice. DCs isolated from mice that have a defect in type I IFN signaling failed to undergo full maturation after Ad vaccination, but surprisingly, these mice mounted strong transgene product-specific CD8+ T cell responses. In these mice, we were able to detect a small number of transduced DCs that expressed high levels of costimulatory molecules, and these DCs were able to stimulate transgene product-specific CD8+ T cells. Thus, type I IFN signaling is an important component of Ad-mediated DC maturation but is dispensable during the generation of transgene product-specific CD8+ T cell responses.
The MyD88-Dependent, but Not the MyD88-Independent, Pathway of TLR4 Signaling Is Important in Clearing Nontypeable Haemophilus influenzae from the Mouse Lung
Authors: Wieland Catharina W. , Florquin Sandrine , Maris Nico A. , Hoebe Kasper , Beutler Bruce , Takeda Kiyoshi , Akira Shizuo , van der Poll Tom
Published: April 2014

TLRs are important for the recognition of conserved motifs expressed by invading bacteria. TLR4 is the signaling receptor for LPS, the major proinflammatory component of the Gram-negative cell wall, whereas CD14 serves as the ligand-binding part of the LPS receptor complex. Triggering of TLR4 results in the activation of two distinct intracellular pathways, one that relies on the common TLR adaptor MyD88 and one that is mediated by Toll/IL-1R domain-containing adaptor-inducing IFN-β (TRIF). Nontypeable Haemophilus influenzae (NTHi) is a common Gram-negative respiratory pathogen that expresses both TLR4 (LPS and lipooligosaccharide) and TLR2 (lipoproteins) ligands. To determine the roles of CD14, TLR4, and TLR2 during NTHi pneumonia, the following studies were performed: 1) Alveolar macrophages from CD14 and TLR4 knockout (KO) mice were virtually unresponsive to NTHi in vitro, whereas TLR2 KO macrophages displayed a reduced NTHi responsiveness. 2) After intranasal infection with NTHi, CD14 and TLR4 KO mice showed an attenuated early inflammatory response in their lungs, which was associated with a strongly reduced clearance of NTHi from the respiratory tract; in contrast, in TLR2 KO mice, lung inflammation was unchanged, and the number of NTHi CFU was only modestly increased at the end of the 10-day observation period. 3) MyD88 KO, but not TRIF mutant mice showed an increased bacterial load in their lungs upon infection with NTHi. These data suggest that the MyD88-dependent pathway of TLR4 is important for an effective innate immune response to respiratory tract infection caused by NTHi.
Arginine-Specific Gingipains from Porphyromonas gingivalis Stimulate Production of Hepatocyte Growth Factor (Scatter Factor) through Protease-Activated Receptors in Human Gingival Fibroblasts in Culture
Authors: Uehara Akiko , Muramoto Koji , Imamura Takahisa , Nakayama Koji , Potempa Jan , Travis James , Sugawara Shunji , Takada Haruhiko
Published: April 2014

Cystein proteinases (gingipains) from Porphyromonas gingivalis cleave a broad range of in-host proteins and are considered to be key virulence factors in the onset and development of adult periodontitis and host defense evasion. In periodontitis, an inflammatory disease triggered by bacterial infection, the production of hepatocyte growth factor (HGF) is induced not only by various factors derived from the host, such as inflammatory cytokines, but also by bacterial components. In this study we examined the possible enhanced production of HGF produced by human gingival fibroblasts upon stimulation with gingipains. Arginine-specific gingipain (Rgp) caused a marked production of HGF into the supernatant, the induction of HGF expression on the cell surface, and the up-regulation of HGF mRNA expression in a dose-dependent and an enzymatic activity-dependent manner. Because it has been reported that Rgp activated protease-activated receptors (PARs), we examined whether the induction of HGF triggered by Rgps on human gingival fibroblasts occurred through PARs. An RNA interference assay targeted to PAR-1 and PAR-2 mRNA revealed that gingipains-induced secretion of HGF was significantly inhibited by RNA interference targeted to PAR-1 and PAR-2. In addition, the Rgps-mediated HGF induction was completely inhibited by the inhibition of phospholipase C and was clearly inhibited by RNA interference targeted to p65, which is an NF-κB component. These results suggest that Rgps activated human gingival fibroblasts to secrete HGF in the inflamed sites and the mechanism(s) involved may actively participate in both inflammatory and reparative processes in periodontal diseases.
Lipopolysaccharide Induces Formyl Peptide Receptor 1 Gene Expression in Macrophages and Neutrophils via Transcriptional and Posttranscriptional Mechanisms
Authors: Mandal Palash , Novotny Michael , Hamilton Thomas A.
Published: April 2014

Bacterial infection promotes the infiltration of inflammatory leukocytes mediated in part by receptors for formyl-methionine-terminated peptides. In this study, we show that LPS can markedly enhance the expression of the formyl peptide receptor gene (FPR1) in mouse macrophages and neutrophils by enhancing transcription and by stabilization of the mRNA. In untreated cells, FPR1 mRNA exhibits a half-life of ∼90 min and this is markedly increased (to >6 h) following stimulation with LPS. Although FPR1 mRNA levels remained elevated over baseline for >20 h after stimulation, the half-life of the message is prolonged only transiently. LPS-induced FPR1 mRNA expression is mediated in part by the intermediate production of secreted factors. First, the response to LPS is partially blocked by the translational inhibitor cycloheximide. Second, a heat-labile but polymyxin B-insensitive factor present in supernatants from LPS-treated cells stimulates enhanced expression of FPR1 mRNA and, like LPS, promotes stabilization of FPR1 mRNA. Furthermore, supernatants from LPS-treated wild-type macrophages can stimulate FPR1 mRNA expression in LPS-insensitive macrophages from TLR4-mutant mice. Elevated FPR1 mRNA expression is also induced in response to ligands for TLR2 and TLR3. TNF-α but not IL-1, IL-6, IFN-β, and IFN-γ can mimic the effects of LPS although other factors apparently also contribute. Collectively, these findings define a distinct molecular pattern of response to TLR stimulation in inflammatory phagocytes and demonstrate that regulation of FPR1 expression is achieved through both transcriptional and posttranscriptional mechanisms.
Differences in Potency of CXC Chemokine Ligand 8-, CC Chemokine Ligand 11-, and C5a-Induced Modulation of Integrin Function on Human Eosinophils
Authors: Ulfman Laurien H. , Alblas Jacqueline , van Aalst Corneli W. , Zwaginga Jaap Jan , Koenderman Leo
Published: April 2014

The hypothesis was tested that different chemoattractants have different effects on the activity of integrins expressed by the human eosinophil. Three chemoattractants, CXCL8 (IL-8), CCL11 (eotaxin-1), and C5a were tested with respect to their ability to induce migration and the transition of eosinophils from a rolling interaction to a firm arrest on activated endothelial cells under flow conditions. CCL11 and C5a induced a firm arrest of eosinophils rolling on an endothelial surface, whereas CXCL8 induced only a transient arrest of the cells. The CXCL8- and CCL11-induced arrest was inhibited by simultaneously blocking α4 integrins (HP2/1) and β2 integrins (IB4). In contrast, the C5a-induced arrest was only inhibited by 30% under these conditions. The potency differences of C5a>CCL11>CXCL8 to induce firm adhesion under flow condition was also observed in migration assays and for the activation of the small GTPase Rap-1, which is an important signaling molecule in the inside-out regulation of integrins. Interestingly, only C5a was able to induce the high activation epitope of αMβ2 integrin recognized by MoAb CBRM1/5. The C5a-induced appearance of this epitope and Rap activation was controlled by phospholipase C (PLC), as was shown with the PLC inhibitor U73122. These data show that different chemoattractants are able to induce distinct activation states of integrins on eosinophils and that optimal chemotaxis is associated with the high activation epitope of the αMβ2 integrin. Furthermore, PLC plays an important role in the inside-out signaling and, thus, the activation status of integrins on eosinophils.
The IL-4 Receptor α-Chain-Binding Cytokines, IL-4 and IL-13, Induce Forkhead Box P3-Expressing CD25+CD4+ Regulatory T Cells from CD25−CD4+ Precursors
Authors: Skapenko Alla , Kalden Joachim R. , Lipsky Peter E. , Schulze-Koops Hendrik
Published: April 2014

The mechanisms underlying the extrathymic generation of CD25+CD4 regulatory T cells (Tregs) are largely unknown. In this study the IL-4R α-chain-binding cytokines, IL-4 and IL-13, were identified as inducers of CD25+ Tregs from peripheral CD25−CD4 naive T cells. IL-4-induced CD25+ Tregs phenotypically and functionally resemble naturally occurring Tregs in that they are anergic to mitogenic stimulation, inhibit the proliferation of autologous responder T cells, express high levels of the Forkhead box P3 and the surface receptors glucocorticoid-induced TNFR family-related protein and CTLA-4, and inhibit effector T cells in a contact-dependent, but cytokine-independent, manner. The IL-4-induced generation of peripheral Tregs was independent of the presence of TGF-β or IL-10, but was dependent on Ag-specific stimulation and B7 costimulation. The significance of the IL-4Rα-binding cytokines in the generation of Ag-specific Tregs was emphasized in a mouse model of oral tolerance, in which neutralization of IL-4 and IL-13 in mice transgenic for the TCR specific for OVA completely inhibited the expansion of OVA-specific Tregs that can be induced in untreated mice by feeding the nominal Ag. Together, our results demonstrate that IL-4 and IL-13 play an important role in generating Forkhead box P3-expressing CD25+ Tregs extrathymically in an Ag-dependent manner and therefore provide an intriguing link between the well-established immunoregulatory capacity of Th2 cells and the powerful CD25+ Treg population. Moreover, our findings might provide the basis for the design of novel therapeutic approaches for targeted immunotherapy with Tregs to known Ags in autoimmune diseases or graft-vs-host reactions.
Selection of T Cell Clones Expressing High-Affinity Public TCRs within Human Cytomegalovirus-Specific CD8 T Cell Responses
Authors: Trautmann Lydie , Rimbert Marie , Echasserieau Klara , Saulquin Xavier , Neveu Bérangère , Dechanet Julie , Cerundolo Vincenzo , Bonneville Marc
Published: April 2014

Assessment of clonal diversity of T cell responses against human CMV (HCMV), a major cause of morbidity in immunodepressed patients, provides important insights into the molecular basis of T cell immunodominance, and has also clinical implications for the immunomonitoring and immunotherapy of HCMV infections. We performed an in-depth molecular and functional characterization of CD8 T cells directed against an immunodominant HLA-A2-restricted epitope derived from HCMV protein pp65 (NLV/A2) in steady state and pathological situations associated with HCMV reactivation. NLV/A2-specific T cells in healthy HCMV-seropositive donors showed limited clonal diversity and usage of a restricted set of TCR Vβ regions. Although TCRβ-chain junctional sequences were highly diverse, a large fraction of NLV/A2-specific T cells derived from distinct individuals showed several recurrent (so-called “public”) TCR features associated in some cases with full conservation of the TCRα chain junctional region. A dramatic clonal focusing of NLV/A2-specific T cells was observed in situations of HCMV reactivation and/or chronic inflammation, which resulted in selection of a single clonotype displaying similar public TCR features in several patients. In most instances the NLV/A2-specific dominant clonotypes showed higher affinity for their Ag than subdominant ones, thus suggesting that TCR affinity/avidity is the primary driving force underlying repertoire focusing along chronic antigenic stimulation.
Innate Immunity and Human B Cell Clonal Expansion: Effects on the Recirculating B2 Subpopulation
Authors: Mongini Patricia K. A. , Inman John K. , Han Hanna , Kalled Susan L. , Fattah Rasem J. , McCormick Steven
Published: April 2014

Foci of autoantigen-specific B lymphocytes in nonlymphoid tissues have been associated with development of autoimmune disease. To better understand the genesis of such ectopic lymphoid tissue, this study investigated whether several B cell-tropic innate immune system molecules, known to be elevated in response to inflammatory stimuli, can cooperate in fostering the T cell-independent clonal expansion of mature human B2 cells under conditions of limiting BCR engagement. Notable synergy was observed between BCR coligation with the C3dg-binding CD21/CD19 costimulatory complex, B cell-activating factor belonging to the TNF family (BAFF), and IL-4 in generating B cell progeny with sustained CD86 and DR expression. The synergy was observed over a wide range of BCR:ligand affinities and involved: 1) cooperative effects at promoting early cell cycle progression and viability; 2) BCR:CD21 coligation-promoted increases in BAFF receptors that were highly regulated by IL-4; 3) reciprocal effects of IL-4 and BAFF at dampening daughter cell apoptosis typical of stimulation by BCR:CD21 and either cytokine alone; and 4) BAFF-sustained expression of antiapoptotic Mcl-1 within replicating lymphoblasts. The results suggest that significant clonal proliferation of recirculating B2 cells occurs upon limited binding to C3dg-coated Ag in an inflammatory in vivo milieu containing both BAFF and IL-4. When rare autoantigen-presenting B cells undergo such expansions, both B cell and T cell autoimmunity may be promoted.
A Role for B Cell-Activating Factor of the TNF Family in Chemically Induced Autoimmunity
Authors: Zheng Yan , Gallucci Stefania , Gaughan John P. , Gross Jane A. , Monestier Marc
Published: April 2014

After exposure to subtoxic doses of heavy metals such as mercury, H-2s mice develop an autoimmune syndrome consisting of the rapid production of IgG autoantibodies that are highly specific for nucleolar autoantigens and a polyclonal increase in serum IgG1 and IgE. In this study, we observe that HgCl2 administration in susceptible mice results in the elevated production of B cell-activating factor of the TNF family ((BAFF) also known as BLyS, TALL-1, zTNF-4, THANK, and TNSF13B), a B cell growth factor belonging to the TNF family. A transmembrane activator and calcium-modulating and cyclophilin ligand interactor (TACI)-Ig fusion protein (which neutralizes both BAFF and a proliferation-inducing ligand (APRIL), another TNF family member) inhibited Hg-induced autoantibody or serum IgE production. These results are discussed in the context of the inhibitory effect of TACI-Ig on B cell maturation at the transitional stage.
Tumor Progression Can Occur despite the Induction of Very High Levels of Self/Tumor Antigen-Specific CD8+ T Cells in Patients with Melanoma
Authors: Rosenberg Steven A. , Sherry Richard M. , Morton Kathleen E. , Scharfman William J. , Yang James C. , Topalian Suzanne L. , Royal Richard E. , Kammula Udai , Restifo Nicholas P. , Hughes Marybeth S. , Schwartzentruber Douglas , Berman David M. , Schwarz Susan L. , Ngo Lien T. , Mavroukakis Sharon A. , White Donald E. , Steinberg Seth M.
Published: April 2014

The identification of many tumor-associated epitopes as nonmutated “self” Ags led to the hypothesis that the induction of large numbers of self/tumor Ag-specific T cells would be prevented because of central and peripheral tolerance. We report in this study on vaccination efforts in 95 HLA-A*0201 patients at high risk for recurrence of malignant melanoma who received prolonged immunization with the “anchor-modified” synthetic peptide, gp100209–217(210M). Vaccination using this altered peptide immunogen was highly effective at inducing large numbers of self/tumor-Ag reactive T cells in virtually every patient tested, with levels as high as 42% of all CD8+ T cells assessed by tetramer analysis. From 1 to 10% of all CD8+ cells were tumor-Ag reactive in 44% of patients and levels >10% were generated in 17% of patients. These studies were substantiated using the ELISPOT assay and a bulk cytokine release assay. Although our data regarding “tumor escape” were inconclusive, some patients had growing tumors that expressed Ag and HLA-A*0201 in the presence of high levels of antitumor T cells. There was no difference in the levels of antitumor Ag-specific T cells in patients who recurred compared with those that remained disease-free. Thus, the mere presence of profoundly expanded numbers of vaccine-induced, self/tumor Ag-specific T cells cannot by themselves be used as a “surrogate marker” for vaccine efficacy. Further, the induction of even high levels of antitumor T cells may be insufficient to alter tumor progression.
Increased Susceptibility to Complement Attack due to Down-Regulation of Decay-Accelerating Factor/CD55 in Dysferlin-Deficient Muscular Dystrophy
Authors: Wenzel Katrin , Zabojszcza Joanna , Carl Miriam , Taubert Semjon , Lass Antje , Harris Claire L. , Ho Mengfatt , Schulz Herbert , Hummel Oliver , Hubner Norbert , Osterziel Karl Josef , Spuler Simone
Published: April 2014

Dysferlin is expressed in skeletal and cardiac muscles. However, dysferlin deficiency results in skeletal muscle weakness, but spares the heart. We compared intraindividual mRNA expression profiles of cardiac and skeletal muscle in dysferlin-deficient SJL/J mice and found down-regulation of the complement inhibitor, decay-accelerating factor/CD55, in skeletal muscle only. This finding was confirmed on mRNA and protein levels in two additional dysferlin-deficient mouse strains, A/J mice and Dysf−/− mice, as well as in patients with dysferlin-deficient muscular dystrophy. In vitro, the absence of CD55 led to an increased susceptibility of human myotubes to complement attack. Evidence is provided that decay-accelerating factor/CD55 is regulated via the myostatin-SMAD pathway. In conclusion, a novel mechanism of muscle fiber injury in dysferlin-deficient muscular dystrophy is demonstrated, possibly opening therapeutic avenues in this to date untreatable disorder.
A Suppressive Oligodeoxynucleotide Enhances the Efficacy of Myelin Cocktail/IL-4-Tolerizing DNA Vaccination and Treats Autoimmune Disease
Authors: Ho Peggy P. , Fontoura Paulo , Platten Michael , Sobel Raymond A. , DeVoss Jason J. , Lee Lowen Y. , Kidd Brian A. , Tomooka Beren H. , Capers Julien , Agrawal Ashish , Gupta Rohit , Zernik Jonathan , Yee Michael K. , Lee Byung J. , Garren Hideki , Robinson William H. , Steinman Lawrence
Published: April 2014

Targeting pathogenic T cells with Ag-specific tolerizing DNA vaccines encoding autoantigens is a powerful and feasible therapeutic strategy for Th1-mediated autoimmune diseases. However, plasmid DNA contains abundant unmethylated CpG motifs, which induce a strong Th1 immune response. We describe here a novel approach to counteract this undesired side effect of plasmid DNA used for vaccination in Th1-mediated autoimmune diseases. In chronic relapsing experimental autoimmune encephalomyelitis (EAE), combining a myelin cocktail plus IL-4-tolerizing DNA vaccine with a suppressive GpG oligodeoxynucleotide (GpG-ODN) induced a shift of the autoreactive T cell response toward a protective Th2 cytokine pattern. Myelin microarrays demonstrate that tolerizing DNA vaccination plus GpG-ODN further decreased anti-myelin autoantibody epitope spreading and shifted the autoreactive B cell response to a protective IgG1 isotype. Moreover, the addition of GpG-ODN to tolerizing DNA vaccination therapy effectively reduced overall mean disease severity in both the chronic relapsing EAE and chronic progressive EAE mouse models. In conclusion, suppressive GpG-ODN effectively counteracted the undesired CpG-induced inflammatory effect of a tolerizing DNA vaccine in a Th1-mediated autoimmune disease by skewing both the autoaggressive T cell and B cell responses toward a protective Th2 phenotype. These results demonstrate that suppressive GpG-ODN is a simple and highly effective novel therapeutic adjuvant that will boost the efficacy of Ag-specific tolerizing DNA vaccines used for treating Th1-mediated autoimmune diseases.
Cutting Edge: Monovalency of CD28 Maintains the Antigen Dependence of T Cell Costimulatory Responses
Authors: Dennehy Kevin M. , Elias Fernando , Zeder-Lutz Gabrielle , Ding Xin , Altschuh Danièle , Lühder Fred , Hünig Thomas
Published: April 2014

CD28 and CTLA-4 are the major costimulatory receptors on naive T cells. But it is not clear why CD28 is monovalent whereas CTLA-4 is bivalent for their shared ligands CD80/86. We generated bivalent CD28 constructs by fusing the extracellular domains of CTLA-4 or CD80 with the intracellular domains of CD28. Bivalent or monovalent CD28 constructs were ligated with recombinant ligands with or without TCR coligation. Monovalent CD28 ligation did not induce responses unless the TCR was coligated. By contrast, bivalent CD28 ligation induced responses in the absence of TCR engagement. To extend these findings to primary cells, we used novel superagonistic and conventional CD28 Abs. Superagonistic Ab D665, but not conventional Ab E18, predominantly ligates CD28 bivalently at low CD28/Ab ratios and induces Ag-independent T cell proliferation. Monovalency of CD28 for its natural ligands is thus essential to provide costimulation without inducing responses in the absence of TCR engagement.
Regulation of T Cell Responses in the Developing Human Fetus
Authors: Michaëlsson Jakob , Mold Jeff E. , McCune Joseph M. , Nixon Douglas F.
Published: April 2014

Although human T cells enter the peripheral lymphoid tissues early during fetal development, the adaptive immune system in the fetus has largely been regarded as functionally immature and unresponsive to stimulation. In this study, we show that depletion of fetal CD4+CD25high T regulatory (TReg) cells, which are present at high frequency in fetal lymphoid tissues, results in vigorous T cell proliferation and cytokine production in vitro, even in the absence of exogenous stimulation. Analysis of CD4+ and CD8+ T cell populations revealed a large subset of cells that expressed the early activation Ag, CD69. We show that this population represents a subset of highly reactive fetal T cells actively suppressed by fetal CD4+CD25high TReg cells during development. These findings indicate that fetal T cells are, in the absence of CD4+CD25high TReg cells, highly responsive to stimulation and provide evidence for an important role for CD4+CD25high TReg cells in controlling T cell responses in utero.
Redundant Role of Chemokines CCL25/TECK and CCL28/MEC in IgA+ Plasmablast Recruitment to the Intestinal Lamina Propria After Rotavirus Infection
Authors: Feng Ningguo , Jaimes María C. , Lazarus Nicole H. , Monak Denise , Zhang Caiqui , Butcher Eugene C. , Greenberg Harry B.
Published: April 2014

Rotaviruses (RV) are the most important cause of severe childhood diarrheal disease. In suckling mice, infection with RV results in an increase in total and virus-specific IgA+ plasmablasts in the small intestinal lamina propria (LP) soon after infection, providing a unique opportunity to study the mechanism of IgA+ cell recruitment into the small intestine. In this study, we show that the increase in total and RV-specific IgA+ plasmablasts in the LP after RV infection can be blocked by the combined administration of Abs against chemokines CCL25 and CCL28, but not by the administration of either Ab alone. RV infection in CCR9 knockout mice still induced a significant accumulation of IgA+ plasmablasts in the LP, which was blocked by the addition of anti-CCL28 Ab, confirming the synergistic role of CCL25 and CCL28. The absence of IgA+ plasmablast accumulation in LP following combined anti-chemokine treatment was not due to changes in proliferation or apoptosis in these cells. We also found that coadministration of anti-CCL25 and anti-CCL28 Abs with the addition of anti-α4 Ab did not further inhibit IgA+ cell accumulation in the LP and that the CCL25 receptor, CCR9, was coexpressed with the intestinal homing receptor α4β7 on IgA+ plasmablasts. Finally, we showed that RV infection was associated with an increase in both CCL25 and CCL28 in the small intestine. Hence, our findings indicate that α4β7 along with either CCR9 or CCR10 are sufficient for mediating the intestinal migration of IgA+ plasmablasts during RV infection.
Regulatory T Cells Inhibit Protein Kinase Cθ Recruitment to the Immune Synapse of Naive T Cells with the Same Antigen Specificity
Authors: Sumoza-Toledo Adriana , Eaton Alfred D. , Sarukhan Adelaida
Published: April 2014

The precise mechanisms by which regulatory T cells operate, particularly their effect on signaling pathways leading to T cell activation, are poorly understood. In this study we have used regulatory T (Treg) cells of known Ag specificity, generated in vivo, to address their effects on early activation events occurring in naive T cells of the same Ag specificity. We found that the Treg cells need to be present at the moment of priming to suppress activation and proliferation of the naive T cell. Furthermore, the Treg cells significantly inhibit the recruitment of protein kinase Cθ (PKCθ) to the immune synapse of the naive T cell as long as both T cells are of the same Ag specificity and are contacting the same APC. Finally, naturally occurring CD4+25+ T cells seem to have the same effect on PKCθ recruitment in CD25− T cells of the same Ag specificity. These results suggest that although additional mechanisms of regulation are likely to exist, inhibition of PKCθ recruitment in the effector T cell may be a common regulatory pathway leading to the absence of NF-κB activation and contributing to the block of IL-2 secretion characteristic of immune suppression.
ERK1−/− Mice Exhibit Th1 Cell Polarization and Increased Susceptibility to Experimental Autoimmune Encephalomyelitis
Authors: Agrawal Anshu , Dillon Stephanie , Denning Timothy L. , Pulendran Bali
Published: April 2014

Activation of MAPK ERK1/2 has been shown to play an important role in Th1/Th2 polarization and in regulating cytokine production from APCs. The ERK family consists of two members ERK1 and ERK2, which share ∼84% identity at the amino acid level and can compensate for each other for most functions. Despite these features, ERK1 and ERK2 do serve different functions, but there is very little information on the contribution of individual forms of ERK on innate and adaptive immune responses. In this study, we describe that ERK1−/− mice display a bias toward Th1 type immune response. Consistent with this observation, dendritic cells from ERK1−/− mice show enhanced IL-12p70 and reduced IL-10 secretion in response to TLR stimulation. Furthermore, serum from ERK1−/− mice had 100-fold higher total IgG2b and 10-fold higher total IgG2a and IgG1 Ab isotype titers, and enhanced levels of Ag-specific IgG2b Ab titers, compared with wild-type mice. Consistent with this enhanced Th1 bias, ERK1−/− mice showed enhanced susceptibility to myelin oligodendrocyte glycoprotein (MOG)35–55 peptide-induced experimental autoimmune encephalomyelitis (EAE) and developed EAE earlier, and with increased severity, compared with wild-type mice. Importantly, there was a profound skewing toward Th1 responses in ERK1−/− mice, with higher IFN-γ production and lower IL-5 production in MOG35–55-primed T cells, as well as an augmentation in the MOG-specific IgG2a and IgG2b Th1 Ab isotypes. Finally, increased infiltrating cells and myelin destruction was observed in the spinal cord of ERK1−/− mice. Taken together, our data suggest that deficiency of ERK1 biases the immune response toward Th1 resulting in increased susceptibility to EAE.
Striking Immunodominance Hierarchy of Naturally Occurring CD8+ and CD4+ T Cell Responses to Tumor Antigen NY-ESO-1
Authors: Jackson Heather , Dimopoulos Nektaria , Mifsud Nicole A. , Tai Tsin Yee , Chen Qiyuan , Svobodova Suzanne , Browning Judy , Luescher Immanuel , Stockert Lisa , Old Lloyd J. , Davis Ian D. , Cebon Jonathan , Chen Weisan
Published: April 2014

Immunodominance has been well-demonstrated in many antiviral and antibacterial systems, but much less so in the setting of immune responses against cancer. Tumor Ag-specific CD8+ T cells keep cancer cells in check via immunosurveillance and shape tumor development through immunoediting. Because most tumor Ags are self Ags, the breadth and depth of antitumor immune responses have not been well-appreciated. To design and develop antitumor vaccines, it is important to understand the immunodominance hierarchy and its underlying mechanisms, and to identify the most immunodominant tumor Ag-specific T cells. We have comprehensively analyzed spontaneous cellular immune responses of one individual and show that multiple tumor Ags are targeted by the patient’s immune system, especially the “cancer-testis” tumor Ag NY-ESO-1. The pattern of anti-NY-ESO-1 T cell responses in this patient closely resembles the classical broad yet hierarchical antiviral immunity and was confirmed in a second subject.
Annexin V Associates with the IFN-γ Receptor and Regulates IFN-γ Signaling
Authors: Leon Carlos , Nandan Devki , Lopez Martin , Moeenrezakhanlou Alireza , Reiner Neil E.
Published: April 2014

Many of the biological activities of IFN-γ are mediated through the IFN-γR3-linked Jak-Stat1α pathway. However, regulation of IFN-γ signaling is not fully understood, and not all responses to IFN-γ are Stat1α dependent. To identify novel elements involved in IFN-γ cell regulation, the cytoplasmic domain of the R2 subunit of the human IFN-γR was used as bait in a yeast two-hybrid screen of a human monocyte cDNA library. This identified annexin A5 (AxV) as a putative IFN-γR binding protein. The interaction was confirmed in pull-down experiments in which a GST-R2 cytoplasmic domain fusion protein was incubated with macrophage lysates. Furthermore, immunoprecipitation using anti-IFN-γR2 Abs showed that AxV interacted with IFN-γR2 to form a stable complex following incubation of cells with IFN-γ. In 293T cells with reduced expression of AxV, brought about by small interfering RNA targeting, activation of Jak2 and Stat1α in response to IFN-γ was enhanced. Inhibition of cell proliferation, a hallmark of the IFN-γ response, also was potentiated in HeLa cells treated with small interfering RNA directed at AxV. Taken together, these results suggest that through an inducible association with the R2 subunit of the IFN-γR, AxV modulates cellular responses to IFN-γ by modulating signaling through the Jak-Stat1 pathway.
Peripheral Tolerance Via the Anterior Chamber of the Eye: Role of B Cells in MHC Class I and II Antigen Presentation
Authors: Ashour Hossam M. , Niederkorn Jerry Y.
Published: April 2014

Ags introduced into the anterior chamber (AC) of the eye induce a form of peripheral immune tolerance termed AC-associated immune deviation (ACAID). ACAID mitigates ocular autoimmune diseases and promotes corneal allograft survival. Ags injected into the AC are processed by F4/80+ APCs, which migrate to the thymus and spleen. In the spleen, ocular APCs induce the development of Ag-specific B cells that act as ancillary APCs and are required for ACAID induction. In this study, we show that ocular-like APCs elicit the generation of Ag-specific splenic B cells that induce ACAID. However, direct cell contact between ocular-like APCs and splenic B cells is not necessary for the induction of ACAID B cells. Peripheral tolerance produced by ACAID requires the participation of ACAID B cells, which induce the generation of both CD4+ regulatory T cells (Tregs) and CD8+ Tregs. Using in vitro and in vivo models of ACAID, we demonstrate that ACAID B cells must express both MHC class I and II molecules for the generation of Tregs. These results suggest that peripheral tolerance induced through the eye requires Ag-presenting B cells that simultaneously present Ags on both MHC class I and II molecules.
Adiponectin Is a Negative Regulator of NK Cell Cytotoxicity
Authors: Kim Kun-yong , Kim Jae Kwang , Han Seung Hyun , Lim Jong-Seok , Kim Keun Il , Cho Dae Ho , Lee Myeong-Sok , Lee Jeong-Hyung , Yoon Do-Young , Yoon Suk Ran , Chung Jin Woong , Choi Inpyo , Kim Eunjoon , Yang Young
Published: April 2014

NK cells are a key component of innate immune systems, and their activity is regulated by cytokines and hormones. Adiponectin, which is secreted from white adipose tissues, plays important roles in various diseases, including hypertension, cardiovascular diseases, inflammatory disorders, and cancer. In this study the effect of adiponectin on NK cell activity was investigated. Adiponectin was found to suppress the IL-2-enhanced cytotoxic activity of NK cells without affecting basal NK cell cytotoxicity and to inhibit IL-2-induced NF-κB activation via activation of the AMP-activated protein kinase, indicating that it suppresses IL-2-enhanced NK cell cytotoxicity through the AMP-activated protein kinase-mediated inhibition of NF-κB activation. IFN-γ enhances NK cell cytotoxicity by causing an increase in the levels of expression of TRAIL and Fas ligand. The production of IFN-γ, one of the NF-κB target genes in NK cells, was also found to be suppressed by adiponectin, accompanied by the subsequent down-regulation of IFN-γ-inducible TRAIL and Fas ligand expression. These results clearly demonstrate that adiponectin is a potent negative regulator of IL-2-induced NK cell activation and thus may act as an in vivo regulator of anti-inflammatory functions.