bluuebunny/crossref_metadata_2025 huggingface dataset:
Allelic Variation in the Ectodomain of the Inhibitory Ly-49G2 Receptor Alters Its Specificity for Allogeneic and Xenogeneic Ligands
Authors: Silver Elizabeth T. , Lavender Kerry J. , Gong Dong-Er , Hazes Bart , Kane Kevin P.
Published: April 2014

The Ly-49 multigene receptor family regulates mouse NK cell functions. A number of Ly-49 genes exhibit allelic variation, but the functional significance of allelic differences in extracellular domains of Ly-49 receptors regarding ligand specificity is largely unknown. Amino acid differences exist in the extracellular domains of the B6 and BALB/c allele products of the inhibitory Ly-49G receptor. We constructed chimeric Ly-49 receptors consisting of common cytoplasmic and transmembrane regions of the activating Ly-49W receptor fused with the ectodomains of the B6 and BALB/c alleles of Ly-49G. Expression of these chimeras in the RNK-16 rat NK cell line allowed us to study the specificity of inhibitory receptor ectodomains as they stimulated NK lytic activity. We found that the ectodomain of the BALB/c allele of Ly-49G recognizes both H-2Dd and Dk class I MHC alleles, whereas the ectodomain of the B6 allele of Ly-49G recognizes Dd, and not Dk. The specificity for Dk as well as Dd of the wild-type Ly-49GBALB/c allele product was confirmed with RNK-16 transfectants of this inhibitory receptor. Furthermore, the ectodomain of the Ly-49GBALB/c allele recognizes a distinct repertoire of xenogeneic ligands that only partially overlaps with that recognized by Ly-49GB6. Our results indicate that allelic variation in Ly-49 extracellular domains can have functional significance by altering Ly-49 receptor specificity for mouse class I MHC and xenogeneic ligands.
CD1 Molecules Efficiently Present Antigen in Immature Dendritic Cells and Traffic Independently of MHC Class II During Dendritic Cell Maturation
Authors: Cao Xiaochun , Sugita Masahiko , van der Wel Nicole , Lai Jean , Rogers Rick A. , Peters Peter J. , Brenner Michael B.
Published: April 2014

Upon exposure to Ag and inflammatory stimuli, dendritic cells (DCs) undergo a series of dynamic cellular events, referred to as DC maturation, that involve facilitated peptide Ag loading onto MHC class II molecules and their subsequent transport to the cell surface. Besides MHC molecules, human DCs prominently express molecules of the CD1 family (CD1a, -b, -c, and -d) and mediate CD1-dependent presentation of lipid and glycolipid Ags to T cells, but the impact of DC maturation upon CD1 trafficking and Ag presentation is unknown. Using monocyte-derived immature DCs and those stimulated with TNF-α for maturation, we observed that none of the CD1 isoforms underwent changes in intracellular trafficking that mimicked MHC class II molecules during DC maturation. In contrast to the striking increase in surface expression of MHC class II on mature DCs, the surface expression of CD1 molecules was either increased only slightly (for CD1b and CD1c) or decreased (for CD1a). In addition, unlike MHC class II, DC maturation-associated transport from lysosomes to the plasma membrane was not readily detected for CD1b despite the fact that both molecules were prominently expressed in the same MIIC lysosomal compartments before maturation. Consistent with this, DCs efficiently presented CD1b-restricted lipid Ags to specific T cells similarly in immature and mature DCs. Thus, DC maturation-independent pathways for lipid Ag presentation by CD1 may play a crucial role in host defense, even before DCs are able to induce maximum activation of peptide Ag-specific T cells.
Containment of Simian Immunodeficiency Virus Infection in Vaccinated Macaques: Correlation with the Magnitude of Virus-Specific Pre- and Postchallenge CD4+ and CD8+ T Cell Responses
Authors: Hel Zdenek , Nacsa Janos , Tryniszewska Elzbieta , Tsai Wen-Po , Parks Robyn Washington , Montefiori David C. , Felber Barbara K. , Tartaglia James , Pavlakis George N. , Franchini Genoveffa
Published: April 2014

Macaques infected with the SIV strain SIVmac251 develop a disease closely resembling human AIDS characterized by high viremia, progressive loss of CD4+ T cells, occurrence of opportunistic infection, cachexia, and lymphomas. We report in this study that vaccination with the genetically attenuated poxvirus vector expressing the structural Ags of SIVmac (NYVAC-SIV-gag, pol, env) in combination with priming with DNA-SIV-gag, env resulted in significant suppression of viremia within 2 mo after mucosal exposure to the highly pathogenic SIVmac251 in the majority of vaccinated macaques. The control of viremia in these macaques was long lasting and inversely correlated to the level of both pre- and postchallenge Gag-specific lymphoproliferative responses, as well as to the level of total SIV-specific CD4+ T lymphocyte responses at the peak of acute viremia as detected by intracellular cytokine-staining assay. Viremia containment also correlated with the frequency of the immunodominant Gag181–189CM9 epitope-specific CD8+ T cells present before the challenge or expanded during acute infection. These data indicate, for the first time, the importance of vaccine-induced CD4+ Th cell responses as an immune correlate of viremia containment. The results presented in this work also further demonstrate the potential of a DNA-prime/attenuated poxvirus-boost vaccine regimen in an animal model that well mirrors human AIDS.
Long-Lived Th2 Memory in Experimental Allergic Asthma
Authors: Mojtabavi Nazanin , Dekan Gerhard , Stingl Georg , Epstein Michelle M.
Published: April 2014

Although life-long immunity against pathogens is beneficial, immunological memory responses directed against allergens are potentially harmful. Because there is a paucity of information about Th2 memory cells in allergic disease, we established a model of allergic asthma in BALB/c mice to explore the generation and maintenance of Th2 memory. We induced disease without the use of adjuvants, thus avoiding Ag depots, and found that unlike allergic asthma in mice immunized with adjuvant, immunizing with soluble and aerosol OVA resulted in pathological lung lesions resembling human disease. To test memory responses we allowed mice with acute disease to recover and then re-exposed them to aerosol OVA a second time. Over 400 days later these mice developed OVA-dependent eosinophilic lung inflammation, airway hyperresponsiveness, mucus hypersecretion, and IgE. Over 1 year after recuperating from acute disease, mice had persistent lymphocytic lung infiltrates, Ag-specific production of IL-4 and IL-5 from spleen and lung cells in vitro, and elevated IgG1. Moreover, when recuperated mice were briefly aerosol challenged, we detected early expression of Th2 cytokine RNA in lungs. Taken together, these data demonstrate the presence of long-lived Th2 memory cells in spleen and lungs involved in the generation of allergic asthma upon Ag re-exposure.
T Cell Requirement for Development of Chronic Ulcerative Dermatitis in E- and P-Selectin-Deficient Mice
Authors: Forlow S. Bradley , White E. James , Thomas Kennard L. , Bagby Gregory J. , Foley Patricia L. , Ley Klaus
Published: April 2014

C57BL/6 mice deficient in E- and P-selectin (E−/−P−/−) kept under specific pathogen-free barrier conditions have high circulating neutrophil counts and develop hypercellular cervical lymph nodes with substantial plasma cell infiltrates, severe ulcerative dermatitis, conjunctivitis, and lung pathology, which eventually lead to premature death. To test the hypothesis that the pathology in E−/−P−/− mice may be caused by dysfunctional lymphocyte activity, we crossed E−/−P−/− mice with recombination activation gene (Rag)-1−/− mice to generate E−/−P−/−Rag-1−/− mice lacking mature T and B lymphocytes. E−/−P−/−Rag-1−/− mice had circulating neutrophil counts and plasma G-CSF levels similar to E−/−P−/− mice. Remarkably, none of the E−/−P−/−Rag-1−/− mice developed conjunctivitis or ulcerative dermatitis typical of E−/−P−/− mice. These mice were overall healthier in appearance than E−/−P−/− mice, and histopathologic changes in the lung were reduced. Cervical lymph nodes in E−/−P−/−Rag-1−/− mice were much smaller than those of E−/−P−/− mice, containing few mononuclear cells and no plasma cells. These data show that the severe disease phenotype of E−/−P−/− mice depends on lymphocyte function. We conclude that a dysregulated immune response in E−/−P−/− mice causes disease development, but is not necessary for elevated neutrophil counts.
Tumor-Induced L-Selectinhigh Suppressor T Cells Mediate Potent Effector T Cell Blockade and Cause Failure of Otherwise Curative Adoptive Immunotherapy
Authors: Peng Liaomin , Kjaergäard Jørgen , Plautz Gregory E. , Awad Mohamed , Drazba Judith A. , Shu Suyu , Cohen Peter A.
Published: April 2014

Tumor-specific effector T cells (TE) are naturally sensitized within the L-selectinlow (CD62Llow) fraction of tumor-draining lymph nodes (TDLN). Whether isolated from day 9 (D9) or day 12 (D12) TDLN, 5 million L-selectinlow TE could be culture activated and adoptively transferred to achieve complete rejection of established intradermal, pulmonary, and brain tumors. Surprisingly, although 25 million unfractionated T cells from D9 TDLN were equally effective, even 100 million unfractionated T cells from D12 TDLN seldom prevented lethal intradermal tumor progression, despite a pronounced therapeutic excess of TE. This highly reproducible treatment failure was due to cotransfer of tumor-induced, L-selectinhigh suppressor T cells (TS) which were also present in D12 TDLN. In contrast, D9 TDLN and normal spleens lacked L-selectinhigh TS. Only those L-selectinhigh D12 TDLN T cells that down-regulated L-selectin during culture activation were suppressive in vivo and in vitro, and, like L-selectinlow TE, trafficked promptly into tumors following i.v. administration. This is the first demonstration that adoptive immunotherapy can fail as a direct result of passenger TS that share certain phenotypic and trafficking features of TE, even when otherwise curative doses of TE have been administered. Furthermore, in contrast to recently described CD4+CD25+ TS and plasmacytoid dendritic cell-activated TS, tumor-induced L-selectinhigh TS prevent tumor rejection via blockade of sensitized, activated TE rather than via afferent blockade.
Regulatory Effect of IFN-κ, A Novel Type I IFN, On Cytokine Production by Cells of the Innate Immune System
Authors: Nardelli Bernardetta , Zaritskaya Liubov , Semenuk Mark , Cho Yun Hee , LaFleur David W. , Shah Devanshi , Ullrich Stephen , Girolomoni Giampiero , Albanesi Cristina , Moore Paul A.
Published: April 2014

IFN-κ is a recently identified type I IFN that exhibits both structural and functional homology with the other type I IFN subclasses. In this study, we have investigated the effect of IFN-κ on cells of the innate immune system by comparing cytokine release following treatment of human cells with either IFN-κ or two recombinant IFN subtypes, IFN-β and IFN-α2a. Although IFN-α2a failed to stimulate monocyte cytokine secretion, IFN-κ, like IFN-β, induced the release of several cytokines from both monocytes and dendritic cells, without the requirement of a costimulatory signal. IFN-κ was particularly effective in inhibiting inducible IL-12 release from monocytes. Unlike IFN-β, IFN-κ did not induce release of IFN-γ by PBL. Expression of the IFN-κ mRNA was observed in resting dendritic cells and monocytes, and it was up-regulated by IFN-γ stimulation in monocytes, while IFN-β mRNA was minimally detectable under the same conditions. Monocyte and dendritic cell expression of IFN-κ was also confirmed in vivo in chronic lesions of psoriasis vulgaris and atopic dermatitis. Finally, biosensor-based binding kinetic analysis revealed that IFN-κ, like IFN-β, binds strongly to heparin (Kd: 2.1 nM), suggesting that the cytokine can be retained close to the local site of production. The pattern of cytokines induced by IFN-κ in monocytes, coupled with the unique induction of IFN-κ mRNA by IFN-γ, indicates a potential role for IFN-κ in the regulation of immune cell functions.
CD4-Dependent Generation of Dominant Transplantation Tolerance Induced by Simultaneous Perturbation of CD154 and LFA-1 Pathways
Authors: Nicolls Mark R. , Coulombe Marilyne , Beilke Joshua , Gelhaus H. Carl , Gill Ronald G.
Published: April 2014

CD154 and LFA-1 (CD11a) represent conceptually distinct pathways of receptor/ligand interactions (costimulation and adhesion/homing, respectively) that have been effectively targeted to induce long-term allograft acceptance and tolerance. In the current study, we determined the relative efficacy and nature of tolerance induced by mAbs specific for these pathways. In vitro analysis indicated that simultaneous targeting of CD154 and LFA-1 resulted in profound inhibition of alloreactivity, suggesting that combined anti-CD154/anti-LFA-1 therapy could be highly effective in vivo. Thus, we evaluated combining mAb therapies targeting CD154 and LFA-1 for inducing transplantation tolerance to pancreatic islet allografts. Monotherapy with either anti-CD154 or anti-LFA-1 was partially effective for inducing long-term allograft survival, whereas the combination resulted in uniform allograft acceptance in high-responder C57BL/6 recipients. This combined therapy was not lymphocyte depleting and did not require the long-term deletion of donor-reactive T lymphocytes to maintain allograft survival. Importantly, combined anti-CD154/anti-LFA therapy uniquely resulted in “dominant” transplantation tolerance. Therefore, simultaneous perturbation of CD154 and LFA-1 molecules can result in profound tolerance induction not accomplished through individual monotherapy approaches. Furthermore, results show that such regulatory tolerance can coexist with the presence of robust anti-donor reactivity, suggesting that active tolerance does not require a corresponding deletion of donor-reactive T cells. Interestingly, although the induction of this regulatory state was highly CD4 dependent, the adoptive transfer of tolerance was less CD4 dependent in vivo.
Homeostasis of Peripheral CD4+ T Cells: IL-2Rα and IL-2 Shape a Population of Regulatory Cells That Controls CD4+ T Cell Numbers
Authors: Almeida Afonso R. M. , Legrand Nicolas , Papiernik Martine , Freitas António A.
Published: April 2014

We show that the lymphoid hyperplasia observed in IL-2Rα- and IL-2-deficient mice is due to the lack of a population of regulatory cells essential for CD4 T cell homeostasis. In chimeras reconstituted with bone marrow cells from IL-2Rα-deficient donors, restitution of a population of CD25+CD4+ T cells prevents the chaotic accumulation of lymphoid cells, and rescues the mice from autoimmune disease and death. The reintroduction of IL-2-producing cells in IL-2-deficient chimeras establishes a population of CD25+CD4+ T cells, and restores the peripheral lymphoid compartments to normal. The CD25+CD4+ T cells regulated selectively the number of naive CD4+ T cells transferred into T cell-deficient hosts. The CD25+CD4+/naive CD4 T cell ratio and the sequence of cell transfer determines the homeostatic plateau of CD4+ T cells. Overall, our findings demonstrate that IL-2Rα is an absolute requirement for the development of the regulatory CD25+CD4+ T cells that control peripheral CD4 T cell homeostasis, while IL-2 is required for establishing a sizeable population of these cells in the peripheral pools.
The Role of the Ets2 Transcription Factor in the Proliferation, Maturation, and Survival of Mouse Thymocytes
Authors: Zaldumbide Arnaud , Carlotti Françoise , Pognonec Philippe , Boulukos Kim E.
Published: April 2014

In this study, we investigated the effects of Ets2 expression on the proliferation, maturation, and survival of thymocytes by establishing transgenic mice that specifically express Ets2 or a dominant negative form of Ets2, Δets2, in the thymus. We show that, in young animals, there are fewer T cells in Δets2 transgenic thymi and that the maturation of these T cells is affected at the CD4−CD8− double-negative to CD4+CD8+ double-positive transition compared with wild-type littermate mice. Partial recovery in the number of thymocytes and full T cell maturation are restored with increasing age of Δets2 transgenic animals. However, thymocytes from adult Δets2 transgenic mice cultured ex vivo are more sensitive to cell death and to glucocorticoid-induced apoptosis than are T cells from control littermate mice. We also show that T cells from adult ets2 transgenic mice proliferate faster than their wild-type littermates. The proliferation and survival of these T cells are clearly affected upon apoptotic signals: glucocorticoid-induced apoptosis induces T cells from ets2 transgenic mice to continue to proliferate in vivo and to survive better ex vivo than T cells from control littermates. It has been shown that c-Myc expression is required for thymic proliferation and improves thymocyte survival of dexamethasone-treated animals. We show that the expression of c-Myc, an Ets2 target, is elevated in T cells freshly isolated from thymi of ets2 transgenic mice pretreated with dexamethasone. Together, these results show that Ets2 plays a role in the proliferation and survival of thymocytes, implicating a Myc-dependent pathway.
DNA Vaccination Breaks Tolerance for a Neo-Self Antigen in Liver: A Transgenic Murine Model of Autoimmune Hepatitis
Authors: Djilali-Saiah Idriss , Lapierre Pascal , Vittozi Susana , Alvarez Fernando
Published: April 2014

Understanding the pathogenesis of autoimmune hepatitis requires an animal model in which chronic progressive immune injury develops spontaneously or with minimal manipulations. The new transgenic mouse model proposed in this study is based on the hypothesis that infectious agents have the potential to initiate autoreactivity through molecular mimicry. A transgenic mouse expressing lymphocytic choriomeningitis virus nucleoprotein (NP) in a H-2b background developed liver injury when vaccinated with plasmids expressing NP as an intracellular or a secretory protein. Coinjection of plasmids coding for NP and IL-12 facilitated the induction of a Th1 phenotype as detected by a specific B lymphocyte response characterized by a predominance of IgG2 subclass anti-NP Abs. CTLs activated in peripheral lymphoid organs by DNA vaccination migrated to the periportal and lobular areas of the liver. Their presence was associated with a significant degree of cytolysis, as evidenced by elevated transaminases several weeks after immunization. As activated specific T lymphocytes proliferated in the periphery and caused cytolysis of target cells, this study suggests that autoimmune hepatitis can be triggered by molecular mimicry, and that local injury may not be essential to initiate autoreactivity in the liver.
Highly Immunogenic and Totally Synthetic Lipopeptides as Self-Adjuvanting Immunocontraceptive Vaccines
Authors: Zeng Weiguang , Ghosh Souravi , Lau Yuk Fai , Brown Lorena E. , Jackson David C.
Published: April 2014

In this study, we describe the synthesis of various lipopeptides based on the sequence of luteinizing hormone-releasing hormone (LHRH) and report on their abilities to induce Abs against this “self” hormone when inoculated into mice in the absence of additional adjuvant. The peptides consisted of a colinear CD4+ T helper cell epitope from the L chain of influenza virus hemagglutinin and LHRH, which has B cell epitopes but no T cell epitopes present in its sequence. Lipids were attached either at the N terminus or between the T cell epitope and LHRH, in the approximate center of the peptide. The lipopeptide constructs displayed different solubilities and immunological properties that depended not only on the lipid content but also on the position of attachment of the lipids. Some of these constructs were highly immunogenic, inducing high titers of Ab, which were capable of efficiently sterilizing female mice when administered in saline by s.c. or intranasal routes. The most effective vaccines were highly soluble, contained the dipalmitoyl-S-glyceryl cysteine moiety, and had this lipid attached at the center of the molecule. The relative ability of the lipopeptides to induce an Ab response in the absence of external adjuvant was reflected by their ability to up-regulate the surface expression of MHC class II molecules on immature dendritic cells. These results demonstrate that the composition and position within peptide vaccines of self-adjuvanting lipid groups can influence the ability to induce the maturation of dendritic cells and, in turn, the magnitude of the resulting Ab response.
Repertoire of Antibody Response in Bone Marrow and the Memory Response Are Differentially Affected in Aging Mice
Authors: Lu Yi-Feng , Cerny Jan
Published: April 2014

The primary burst of Ab and germinal center (GC) formation in response to T-dependent Ag is compromised in aging mice. Here we examine the effects of aging on the post-GC phase of memory B cell differentiation and the late Ab repertoire maturation in bone marrow (BM) in mice immunized with a hapten nitrophenyl coupled to chicken γ-globulin. Specific Ab-forming cells (AFC) with mutated VH genes accumulated preferentially in the BM of aged mice, although the AFC numbers and average number of mutations per VH were lower, and the D gene usage was less restricted compared with those in the young animals. However, the repertoire of AFC after an Ag boost demonstrated the hallmarks of Ag selection, including the recurrent mutations and canonical VD rearrangements, similar to the late primary response in young animals. It is postulated that the Ab repertoire maturation in aged mice is delayed and may be notably improved by repeated immunizations.
Efficient Priming of CD4+ and CD8+ T Cells by DNA Vaccination Depends on Appropriate Targeting of Sufficient Levels of Immunologically Relevant Antigen to Appropriate Processing Pathways
Authors: Rush Catherine , Mitchell Tim , Garside Paul
Published: April 2014

The initial cellular events and interactions that occur following DNA immunization are likely to be key to determining the character and magnitude of the resulting immune response, and as such, a better understanding of these events could ultimately lead to the design of more effective pathogen-appropriate DNA vaccines. Therefore, we have used a variety of sensitive cell-based techniques to study the induction of adaptive immunity in vivo. We examined the efficacy of induction of Ag-specific CD4+ and CD8+ T cell responses in vivo by the adoptive transfer of fluorescently labeled Ag-specific TCR transgenic T cells and have demonstrated how such approaches can be used to study the effect of simple DNA construct manipulations on immunological priming. OVA-specific CD8+ and CD4+ T cells were activated and divided in vivo following immunization with DNA constructs that targeted OVA expression to different subcellular locations; however, the kinetics and degree of cell proliferation were dependent on the cellular location of the expressed protein. DNA vectors encoding cell-associated OVA resulted in greater CD8+ T cell division compared with other forms of OVA. In contrast, soluble secreted OVA targeted to the classical secretory pathway enhanced division of CD4+ T cells. Furthermore, the inclusion of mammalian introns to enhance protein expression increased the ability of poorly immunogenic forms of Ag to activate naive T cells, indicating that not only the location, but also the amount of Ag expression, is important for efficient T cell priming following DNA injection.
Single T Cell Receptor-Mediated Recognition of an Identical HIV-Derived Peptide Presented by Multiple HLA Class I Molecules
Authors: Ueno Takamasa , Tomiyama Hiroko , Takiguchi Masafumi
Published: April 2014

A dual specific human CTL clone harboring one β and two inframe α transcripts of TCR was previously reported to recognize an HIV Pol-derived nonapeptide (IPLTEEAEL) endogenously presented by both syngeneic HLA-B*3501 and HLA-B*5101. In the current study, a retrovirus-mediated TCR transfer of individual α- and β-chains to TCR-negative hybridoma showed that Vα12.1 TCR in complex with Vβ5.6 were responsible for the peptide-specific response in the context of both HLA-B*3501 and HLA-B*5101, confirming single TCR-mediated dual specificity. The second TCR-α chain was not somehow expressed on the cell surface. Remarkably, the Vα12.1/Vβ5.6 TCR also recognized the same peptide presented by allogeneic HLA class I molecules that share the similar peptide-binding motifs, such as HLA-B*5301 and HLA-B*0702. The sensitivity of peptide recognition by the Vα12/Vβ5.6 TCR appeared to be comparable when the peptide was presented by syngeneic and allogeneic HLA class I molecules, with changes in T cell responsiveness caused largely by peptide-binding capacity. Moreover, the CTL clone bearing Vα12.1/Vβ5.6 TCR showed substantial cytolytic activity against the peptide-loaded cells expressing HLA-B*3501, HLA-B*5101, HLA-B*5301, or HLA-B*0702, providing further evidence that a single TCR complex can recognize the same peptide presented by a broad range of HLA class I molecules. A TCR with fine specificity for an HIV Ag but broad specificity to multiple HLA molecules may provide an advantage to the generation of allorestricted, peptide-specific T cells, and thus could be a potent candidate for immunotherapy against HIV infection.
Bovine γδ T Cell Subsets Express Distinct Patterns of Chemokine Responsiveness and Adhesion Molecules: A Mechanism for Tissue-Specific γδ T Cell Subset Accumulation
Authors: Wilson Eric , Hedges Jodi F. , Butcher Eugene C. , Briskin Michael , Jutila Mark A.
Published: April 2014

Subsets of γδ T cells localize to distinct tissue sites in the absence of exogenous Ag stimulation or development of effector/memory cells. Selective lymphocyte homing from the blood into tissues is controlled by a multistep process involving vascular and lymphocyte adhesion molecules, and G protein-linked chemokine receptors. The role of these mechanisms in the tissue tropism of γδ T cells is still poorly understood. In this study, we demonstrate that a subset of γδ T cells, most of which express an antigenically distinct TCR and are characterized by coexpression of CD8, selectively accumulated in tissues that expressed high levels of the mucosal vascular addressin, mucosal addressin cell adhesion molecule 1. These cells expressed higher levels of α4β7 integrins than other γδ T cell subsets and selectively migrated to the CCR7 ligand secondary lymphoid-tissue chemokine (CCL21). Integrin activation by CCL21 selectively increased CD8+γδ T cell binding to recombinant mucosal addressin cell adhesion molecule 1. These results suggest that the tropism of circulating CD8+γδ T cells for mucosal tissues is due, at least in part, to selective developmental expression of adhesion molecules and chemokine receptors.
Selective Delivery of Augmented IL-2 Receptor Signals to Responding CD8+ T Cells Increases the Size of the Acute Antiviral Response and of the Resulting Memory T Cell Pool
Authors: Cheng Laurence E. , Greenberg Philip D.
Published: April 2014

CD8+ T cells respond to IL-2 produced both endogenously and by CD4+ Th during an antiviral response. However, IL-2R signals can potentially promote CD8+ T cell death as well as proliferation, making it unclear whether IL-2R signals provide a predominantly positive or negative effect upon CD8+ T cell responses to viral infection. To more precisely define the direct role of IL-2R signaling on CD8+ T cells during the response to a virus, we examined the effect of delivering augmented IL-2R signals selectively to CD8+ T cells responding to lymphocytic choriomeningitis virus infection. Although naive CD8+ T cells are competent to produce IL-2, CD8+ T cells lose this capacity upon differentiation into effector CD8+ T cells. However, effector CD8+ T cells do retain the capacity to produce GM-CSF upon Ag stimulation. Thus, to deliver enhanced autocrine IL-2R signals to CD8+ T cells, we established a transgenic mouse strain expressing a chimeric GM-CSF/IL-2R (GMIL2R). As GM-CSF production is Ag dependent, the GMIL2R delivers an augmented IL-2R signal exclusively to CD8+ T cells responding to Ag. Following lymphocytic choriomeningitis virus infection, GMIL2R transgenic mice exhibited an increase in both the peak CD8+ T cell response achieved and the size of the resulting memory pool established. Upon secondary viral challenge, the GMIL2R also enhanced the proliferative response of memory CD8+ T cells. Thus, our findings indicate that IL-2 delivery to responding CD8+ T cells is a limiting factor in both the acute and memory antiviral responses.
A Positive Regulatory Role for Suppressor of Cytokine Signaling 1 in IFN-γ-Induced MHC Class II Expression in Fibroblasts
Authors: Ilangumaran Subburaj , Finan Dina , La Rose José , Raine Jason , Silverstein Anna , De Sepulveda Paulo , Rottapel Robert
Published: April 2014

Suppressor of cytokine signaling 1 (SOCS1) is rapidly induced following stimulation by several cytokines. SOCS1 negatively regulates cytokine receptor signal transduction by inhibiting Janus family tyrosine kinases. Lack of such feedback regulation underlies the premature death of SOCS1−/− mice due to unbridled IFN-γ signaling. We used mouse embryo fibroblasts derived from SOCS1−/− mice to investigate the role of SOCS1 in IFN-γ signaling pathways. SOCS1−/− fibroblasts were exquisitely sensitive to the IFN-γ-mediated growth arrest and showed sustained STAT1 phosphorylation. However, SOCS1−/− fibroblasts were inefficient in MHC class II surface expression following IFN-γ stimulation, despite a marked induction of the MHC class II transactivator and MHC class II gene expression. Retroviral transduction of wild-type SOCS1 relieved the growth-inhibitory effects of IFN-γ in SOCS1−/− fibroblasts by inhibiting STAT1 activation. SOCS1R105K, carrying a mutation within the phosphotyrosine-binding pocket of the Src homology 2 domain, did not inhibit STAT1 phosphorylation, yet considerably inhibited IFN-γ-mediated growth arrest. Strikingly, expression of SOCS1R105K restored the IFN-γ-induced MHC class II expression in SOCS1−/− cells, indicating that expression of SOCS1 facilitates MHC class II expression in fibroblasts. Our results show that SOCS1, in addition to its negative regulatory role of inhibiting Janus kinases, has an unanticipated positive regulatory function in retarding the degradation of IFN-γ-induced MHC class II proteins in fibroblasts.
The β2-Adrenergic Agonist Salbutamol Potentiates Oral Induction of Tolerance, Suppressing Adjuvant Arthritis and Antigen-Specific Immunity
Authors: Cobelens Pieter M. , Kavelaars Annemieke , Vroon Anne , Ringeling Marion , van der Zee Ruurd , van Eden Willem , Heijnen Cobi J.
Published: April 2014

Therapeutic protocols for treating autoimmune diseases by feeding autoantigens during the disease process have not been very successful to date. In vitro it has been shown that β-adrenergic agonists inhibit pro-inflammatory cytokine production and up-regulate anti-inflammatory cytokine production. We hypothesized that the protective effect of oral administration of Ag would be enhanced by oral coadministration of the β2-adrenergic agonist salbutamol. Here we demonstrate that oral administration of salbutamol in combination with the Ag mycobacterial 65-kDa heat shock protein increased the efficacy of disease-suppressive tolerance induction in rat adjuvant arthritis. To study the mechanism of salbutamol in more detail, we also tested oral administration of salbutamol in an OVA tolerance model in BALB/c mice. Oral coadministration of OVA/salbutamol after immunization with OVA efficiently suppressed both cellular and humoral responses to OVA. Coadministration of salbutamol was associated with an immediate increase in IL-10, TGF-β, and IL-1R antagonist in the intestine. The tolerizing effect of salbutamol/OVA was maintained for at least 12 wk. At this time point IFN-γ production in Ag-stimulated splenocytes was increased in the OVA/salbutamol-treated animals. In conclusion, salbutamol can be of great clinical benefit for the treatment of autoimmune diseases by promoting oral tolerance induction.
Dynamic Association of CD45 with Detergent-Insoluble Microdomains in T Lymphocytes
Authors: Edmonds Stuart D. , Ostergaard Hanne L.
Published: April 2014

The receptor-like protein tyrosine phosphatase CD45 is essential for TCR signal transduction. Substrates of CD45 include the protein tyrosine kinases p56lck and p59fyn, both of which have been shown to be enriched in detergent-insoluble microdomains. Here we find that there is a cholesterol-dependent association between CD45 and the raft-associated protein linker for activation of T cells, suggesting that CD45 and linker for activation of T cells may colocalize in lipid rafts. Consistent with this observation, we find that ∼5% of total CD45 can be detected in Triton X-100-insoluble buoyant fractions of sucrose gradients, demonstrating that CD45 is not excluded from lipid rafts. Upon stimulation of T cells with anti-CD3, there is a reduction in the amount of CD45 found associating with lipid rafts. Our data suggest that CD45 is present in lipid rafts in T cells before activation, perhaps to activate raft-associated p56lck, allowing membrane-proximal signaling events to proceed. Furthermore, the reduction in CD45 content of lipid rafts after CD3 stimulation may serve to limit the amounts of activated p56lck in rafts and thus possibly the duration of T cell responses.
HLA-DR4 Molecules in Neuroendocrine Epithelial Cells Associate to a Heterogeneous Repertoire of Cytoplasmic and Surface Self Peptides
Authors: Muntasell Aura , Carrascal Montserrat , Serradell Laurence , Veelen Peter van , Verreck Frank , Koning Frits , Raposo Graça , Abián Joaquín , Jaraquemada Dolores
Published: April 2014

Expression of MHC class II genes by epithelial cells is induced in inflammatory conditions such as autoimmunity and organ transplantation. Class II ligands generated by the epithelial cell processing mechanisms are unknown, although some unique epitopes have been described in epithelial cells that B cells could not generate. Epithelial cells are the targets of autoreactive T cell responses in autoimmune diseases and of transplant rejection processes, which may involve recognition of cell type-specific epitopes. In the present report, we have compared the DR4-associated repertoire and the intracellular distribution of class II, invariant chain (Ii), and DM molecules between a human DR4-, Ii-, and DM-transfected rat neuroendocrine epithelial cell line and a homozygous DR4 (DRB1*0401) lymphoblastoid B cell line, by mass spectrometry sequencing techniques, and immunoelectron microscopy. The epithelial cells chosen for transfection, RINm5F, are rat insular cells widely used for human studies of autoimmune diabetes. The results revealed a remarkably heterogeneous pool of self protein-derived peptides from the cell surface and various intracellular compartments, including the cytosol and secretory vesicles in epithelial cells, compared with a very restricted homogeneous repertoire in lymphoblastoid B cell lines, where few epitopes from surface molecules were predominant. The generation of distinct DR4-associated peptide repertoires in these two cell types could be due to the effect of several factors including differences in subcellular location of Ii and DM molecules, differential DO expression, and cell type-specific mechanisms of class II ligand generation. This is specially relevant to processes involving epithelial T cell interactions such as organ-specific autoimmunity and transplant rejection.
Cysteine Residues Required for the Attachment of the Light Chain in Human IgA2
Authors: Chintalacharuvu Koteswara R. , Yu Li J. , Bhola Nishant , Kobayashi Kunihiko , Fernandez Christine Z. , Morrison Sherie L.
Published: April 2014

In humans, there are two subclasses of IgA, IgA1 and IgA2, with IgA2 existing as three allotypes, IgA2m(1), IgA2m(2) and IgA2(n). In IgA1, Cys133 in CH1 forms the disulfide bond to the L chain. Our previous studies indicated that in IgA2 lacking Cys133, a disulfide bond forms between the α-chain and the L chain when Cys220 is followed by Arg221, but not when Cys220 is followed by Pro221, suggesting that the Cys in CH1 might be involved in disulfide bonding to the L chain. However, here we show that covalent assembly of the H and L chains in IgA2(n) requires hinge-proximal Cys241 and Cys242 in CH2 and not Cys196 or Cys220 in CH1. Using pulse-chase experiments, we have demonstrated that wild-type IgA2(n) with Arg221 and Cys241 and Cys242 assembles through a disulfide-bonded HL intermediate. In contrast, the major intermediate for IgA2 m(1) with Pro221 assembly was H2 even though both Cys241 and Cys242 were present. Only a small fraction of IgA2 m(1) assembles through disulfide-bonded HL. Overall, our studies indicate that for IgA2 covalent assembly of the H and L chains requires the hinge-proximal cysteines in CH2 and that the structure of CH1 influences the efficiency with which this covalent bond forms.
Inhibition of HIV-1 Infection by Small Interfering RNA-Mediated RNA Interference
Authors: Capodici John , Karikó Katalin , Weissman Drew
Published: April 2014

RNA interference (RNAi) is an ancient antiviral response that processes dsRNA and associates it into a nuclease complex that identifies RNA with sequence homology and specifically cleaves it. We demonstrate that RNAi mediated by 21-bp dsRNA specifically inhibits HIV-1 infection of permanent cell lines and primary CD4+ T cells. Inhibition of HIV replication was measured by p24 Gag protein content in supernatant, Northern blot analysis, and DNA PCR for products of reverse transcription. The inhibition occurred at two points in the viral life cycle, after fusion and before reverse transcription and during transcription of viral RNA from integrated provirus. Treatment of HIV-infected activated CD4+ T cells with a fluorine-derivatized siRNA that is resistant to RNase A yielded similar inhibition of HIV infection. In addition, the derivatized siRNA could be delivered without lipofectin complexing and in the presence of serum. The identification of RNAi activity against HIV-1 presents a new approach to study viral infections and a proof of concept of RNAi antiviral activity in mammalian cells.
Dysregulation of LPS-Induced Toll-Like Receptor 4-MyD88 Complex Formation and IL-1 Receptor-Associated Kinase 1 Activation in Endotoxin-Tolerant Cells
Authors: Medvedev Andrei E. , Lentschat Arnd , Wahl Larry M. , Golenbock Douglas T. , Vogel Stefanie N.
Published: April 2014

Prior exposure to LPS induces a transient state of cell refractoriness to subsequent LPS restimulation, known as endotoxin tolerance. Induction of LPS tolerance has been reported to correlate with decreased cell surface expression of the LPS receptor complex, Toll-like receptor 4 (TLR4)/MD-2. However, other results have underscored the existence of mechanisms of LPS tolerance that operate downstream of TLR4/MD-2. In the present study we sought to delineate further the molecular basis of LPS tolerance by examining the TLR4 signaling pathway in endotoxin-tolerant cells. Pretreatment of human monocytes with LPS decreased LPS-mediated NF-κB activation, p38 mitogen-activated protein kinase phosphorylation, and TNF-α gene expression, documenting the induction of endotoxin tolerance. FACS and Western blot analyses of LPS-tolerant monocytes showed increased TLR2 expression, whereas TLR4 expression levels were not affected. Comparable levels of mRNA and protein for myeloid differentiation factor 88 (MyD88), IL-1R-associated kinase 1 (IRAK-1), and TNFR-associated factor-6 were found in normal and LPS-tolerant monocytes, while MD-2 mRNA expression was slightly increased in LPS-tolerant cells. LPS induced the association of MyD88 with TLR4 and increased IRAK-1 activity in medium-pretreated cells. In LPS-tolerant monocytes, however, MyD88 failed to be recruited to TLR4, and IRAK-1 was not activated in response to LPS stimulation. Moreover, endotoxin-tolerant CHO cells that overexpress human TLR4 and MD-2 also showed decreased IRAK-1 kinase activity in response to LPS despite the failure of LPS to inhibit cell surface expression of transfected TLR4 and MD-2 proteins. Thus, decreased TLR4-MyD88 complex formation with subsequent impairment of IRAK-1 activity may underlie the LPS-tolerant phenotype.
Tumor Cell Lysate-Pulsed Dendritic Cells Are More Effective Than TCR Id Protein Vaccines for Active Immunotherapy of T Cell Lymphoma
Authors: Gatza Erin , Okada Craig Y.
Published: April 2014

TCR Id protein conjugated to keyhole limpet hemocyanin (KLH) (TCR Id:KLH) and injected with a chemical adjuvant (QS-21) induces a protective, Id-specific immune response against the murine T cell lymphoma, C6VL. However, Id-based immunotherapy of C6VL has not demonstrated therapeutic efficacy in tumor-bearing mice. We report here that C6VL lysate-pulsed dendritic cells (C6VL-DC) vaccines display enhanced efficacy in both the prevention and the therapy of T cell lymphoma compared with TCR Id:KLH with QS-21 vaccines. C6VL-DC vaccines stimulated potent tumor-specific immunity that protected mice against lethal challenge with C6VL and significantly enhanced the survival of tumor-bearing mice. Tumor-specific proliferation and secretion of IFN-γ indicative of a Th1-type immune response were observed upon ex vivo stimulation of vaccine-primed lymph node cells. Adoptive transfer of immune T cell-enriched lymphocytes was sufficient to protect naive recipients from lethal tumor challenge. Furthermore, CD8+ T cells were absolutely required for tumor protection. Although C6VL-DC and control vaccines stimulated low levels of tumor-specific Ab production in mice, Ab levels did not correlate with the protective ability of the vaccine. Thus, tumor cell lysate-pulsed DC vaccines appear to be an effective approach to generate potent T cell-mediated immune responses against T cell malignancies without requiring identification of tumor-specific Ags or patient-specific Id protein expression.
Lymphotoxin-α-Deficient Mice Make Delayed, But Effective, T and B Cell Responses to Influenza
Authors: Lund Frances E. , Partida-Sánchez Santiago , Lee Byung O. , Kusser Kimberly L. , Hartson Louise , Hogan Robert J. , Woodland David L. , Randall Troy D.
Published: April 2014

Lymphotoxin-α−/− (LTα−/−) mice are thought to be unable to generate effective T and B cell responses. This is attributed to the lack of lymph nodes and the disrupted splenic architecture of these mice. However, despite these defects we found that LTα−/− mice could survive infection with a virulent influenza A virus. LTα−/− mice and normal wild-type mice infected with influenza A generated similar numbers of influenza-specific CD8 T cells that were able to produce IFN-γ and kill target cells presenting influenza peptides. Furthermore influenza-infected LTα−/− mice produced high titers of influenza-specific IgM, IgG, and IgA. However, both CD8 and B cell immune responses were delayed in LTα−/− mice by 2–3 days. The delayed cellular and humoral immune response was sufficient to mediate viral clearance in LTα−/− mice that were infected with relatively low doses of influenza virus. However, when LTα−/− mice were infected with larger doses of influenza, they succumbed to infection before the immune response was initiated. These results demonstrate that neither LTα nor constitutively organized lymphoid tissues, such as lymph nodes and spleen, are absolutely required for the generation of effective immunity against the respiratory virus influenza A. However, the presence of LTα and/or lymph nodes does accelerate the initiation of immune responses, which leads to protection from larger doses of virus.
Platelet-Activating Factor Activates Two Distinct Effector Pathways in Human Eosinophils
Authors: Kato Masahiko , Kimura Hirokazu , Motegi Youichi , Tachibana Atsushi , Minakami Hisanori , Morikawa Akihiro , Kita Hirohito
Published: April 2014

In granulocytes, platelet-activating factor (PAF) shares many of its biological effects with other chemotactic factors, such as FMLP, complement fragments, and lipid mediators. Two unique effects are that PAF is relatively resistant to pertussis toxin (PTX) and that PAF activates the inflammatory functions of eosinophils more strongly than it activates those of neutrophils. To investigate the molecular mechanisms of the responses of eosinophils to PAF, we analyzed superoxide anion production by a chemiluminescence method that provides real-time kinetic data for the cellular responses. We found that PAF induced bimodal superoxide anion production in human eosinophils, consisting of an intense, but transient, first phase and a larger and sustained second phase. In contrast, PAF induced essentially a transient unimodal response in human neutrophils. The two phases of eosinophil response were mediated by distinct cellular mechanisms: the second phase was highly dependent on cellular adhesion and β2 integrins, but the first phase was independent of both adhesion and β2 integrins. The upstream signaling mechanisms were also different: the second phase was mediated by PTX-resistant G-protein(s) and through activation of phosphatidylinositol 3-kinase, while the first phase was mediated by PTX-sensitive G-protein(s). Furthermore, the second-phase response was ∼100-fold more resistant to inhibition by a competitive PAF receptor antagonist than the first phase. Thus, eosinophils and neutrophils react differently to PAF, and PAF activates two separate and distinct effector pathways in human eosinophils. These two activation pathways may explain the eosinophils’ strong and diverse biological responses to PAF.
TCRγδ+ and CD161+ Thymocytes Express HIV-1 in the SCID-hu Mouse, Potentially Contributing to Immune Dysfunction in HIV Infection
Authors: Gurney Kevin B. , Yang Otto O. , Wilson S. Brian , Uittenbogaart Christel H.
Published: April 2014

The vast diversity of the T cell repertoire renders the adaptive immune response capable of recognizing a broad spectrum of potential antigenic peptides. However, certain T cell rearrangements are conserved for recognition of specific pathogens, as is the case for TCRγδ cells. In addition, an immunoregulatory class of T cells expressing the NK receptor protein 1A (CD161) responds to nonpeptide Ags presented on the MHC-like CD1d molecule. The effect of HIV-1 infection on these specialized T cells in the thymus was studied using the SCID-hu mouse model. We were able to identify CD161-expressing CD3+ cells but not the CD1d-restricted invariant Vα24/Vβ11/CD161+ NK T cells in the thymus. A subset of TCRγδ cells and CD161-expressing thymocytes express CD4, CXCR4, and CCR5 during development in the thymus and are susceptible to HIV-1 infection. TCRγδ thymocytes were productively infectable by both X4 and R5 virus, and thymic HIV-1 infection induced depletion of CD4+ TCRγδ cells. Similarly, CD4+CD161+ thymocytes were depleted by thymic HIV-1 infection, leading to enrichment of CD4−CD161+ thymocytes. Furthermore, compared with the general CD4-negative thymocyte population, CD4−CD161+ NK T thymocytes exhibited as much as a 27-fold lower frequency of virus-expressing cells. We conclude that HIV-1 infection and/or disruption of cells important in both innate and acquired immunity may contribute to the overall immune dysfunction seen in HIV-1 disease.