bluuebunny/crossref_metadata_2025_split huggingface dataset:
Attenuation of IL-7 Receptor Signaling Is Not Required for Allelic Exclusion
Authors: Will Wynette M. , Aaker Joshua D. , Burchill Matthew A. , Harmon Ian R. , O’Neil Jennifer J. , Goetz Christine A. , Hippen Keli L. , Farrar Michael A. 
Published: April 2014

Abstract
Allelic exclusion prevents pre-B cells from generating more than one functional H chain, thereby ensuring the formation of a unique pre-BCR. The signaling processes underlying allelic exclusion are not clearly understood. IL-7R-dependent signals have been clearly shown to regulate the accessibility of the Ig H chain locus. More recent work has suggested that pre-BCR-dependent attenuation of IL-7R signaling returns the H chain loci to an inaccessible state; this process has been proposed to underlie allelic exclusion. Importantly, this model predicts that preventing pre-BCR-dependent down-regulation of IL-7R signaling should interfere with allelic exclusion. To test this hypothesis, we made use of transgenic mice that express a constitutively active form of STAT5b (STAT5b-CA). STAT5b-CA expression restores V(D)J recombination in IL-7R−/− B cells, demonstrating that IL-7 regulates H chain locus accessibility and V(D)J recombination via STAT5 activation. To examine the effects of constitutively active STAT5b on allelic exclusion, we crossed STAT5b-CA mice (which express the IgMb allotype) to IgMa allotype congenic mice. We found no difference in the percentage of IgMa/IgMb-coexpressing B cells in STAT5b-CA vs littermate control mice; identical results were observed when crossing STAT5b-CA mice with hen egg lysozyme (HEL) H chain transgenic mice. The HEL transgene enforces allelic exclusion, preventing rearrangement of endogenous H chain genes; importantly, rearrangement of endogenous H chain genes was suppressed to a similar degree in STAT5b-CA vs HEL mice. Thus, attenuation of IL-7R/STAT5 signaling is not required for allelic exclusion.
Soluble MHC-Peptide Complexes Containing Long Rigid Linkers Abolish CTL-Mediated Cytotoxicity
Authors: Angelov Georgi S. , Guillaume Philippe , Cebecauer Marek , Bosshard Giovanna , Dojcinovic Danijel , Baumgaertner Petra , Luescher Immanuel F. 
Published: April 2014

Abstract
Soluble MHC-peptide (pMHC) complexes induce intracellular calcium mobilization, diverse phosphorylation events, and death of CD8+ CTL, given that they are at least dimeric and coengage CD8. By testing dimeric, tetrameric, and octameric pMHC complexes containing spacers of different lengths, we show that their ability to activate CTL decreases as the distance between their subunit MHC complexes increases. Remarkably, pMHC complexes containing long rigid polyproline spacers (≥80 Å) inhibit target cell killing by cloned S14 CTL in a dose- and valence-dependent manner. Long octameric pMHC complexes abolished target cell lysis, even very strong lysis, at nanomolar concentrations. By contrast, an altered peptide ligand antagonist was only weakly inhibitory and only at high concentrations. Long Db-gp33 complexes strongly and specifically inhibited the Db-restricted lymphocytic choriomeningitis virus CTL response in vitro and in vivo. We show that complications related to transfer of peptide from soluble to cell-associated MHC molecules can be circumvented by using covalent pMHC complexes. Long pMHC complexes efficiently inhibited CTL target cell conjugate formation by interfering with TCR-mediated activation of LFA-1. Such reagents provide a new and powerful means to inhibit Ag-specific CTL responses and hence should be useful to blunt autoimmune disorders such as diabetes type I.
Loss of the Surface Antigen 3G11 Characterizes a Distinct Population of Anergic/Regulatory T Cells in Experimental Autoimmune Encephalomyelitis
Authors: Zhang Guang-Xian , Yu Shuo , Calida Divina , Zhao Zhao , Gran Bruno , Kamoun Malek , Rostami Abdolmohamad 
Published: April 2014

Abstract
T cell anergy is an important mechanism in the induction of peripheral tolerance against autoimmune diseases, yet no surface marker unique to anergic T cells in these diseases has been identified. In this study we induced in vivo anergy by i.v. tolerance against experimental autoimmune encephalomyelitis in myelin basic protein TCR transgenic mice, and showed that the hyporesponsiveness of autoantigen-reactive T cells from tolerized mice was associated with a dramatic loss of 3G11, a cell surface molecule on the surface of CD4+ T cells. Purified 3G11−CD4+ T cells lost autoantigen-induced proliferation and IL-2 production, whereas 3G11+CD4+ T cells retained responsiveness. Furthermore, 3G11− T cells actively suppressed proliferation and Th1 cytokine production of 3G11+ T cells and splenocytes of nontolerized mice. Active suppression by 3G11− T cells was at least partially due to soluble immunoregulatory factors, including IL-10. The T regulatory property of 3G11− T cells was confirmed in vivo because the transfer of purified 3G11− T cells effectively suppressed clinical experimental autoimmune encephalomyelitis. We conclude that loss of the surface molecule 3G11 characterizes a distinct population of anergic/regulatory T cells. This is the first demonstration of the ability to identify and purify anergic T cells by a distinct cell surface marker in an autoimmune disease and paves the way for a better understanding of the mechanism of tolerance in autoimmune diseases.
CTL Adoptive Immunotherapy Concurrently Mediates Tumor Regression and Tumor Escape
Authors: Liu Kebin , Caldwell Sheila A. , Greeneltch Kristy M. , Yang Dafeng , Abrams Scott I. 
Published: April 2014

Abstract
Tumor escape and recurrence are major impediments for successful immunotherapy. It is well-documented that the emergence of Ag-loss variants, as well as regulatory mechanisms suppressing T cell function, have been linked to inadequate antitumor activity. However, little is known regarding the role of Fas-mediated cytotoxicity by tumor-specific CD8+ CTL in causing immune evasion of Fas resistant variants during adoptive immunotherapy. In this study, we made use of an adoptive transfer model of experimental lung metastasis using tumor-specific CTL as a relevant immune-based selective pressure, and wherein the Fas ligand pathway was involved in the antitumor response. Surviving tumor cells were recovered and examined for alterations in antigenic, functional, and biologic properties. We showed that diminished susceptibility to Fas-mediated cytotoxicity in vivo was an important determinant of tumor escape following CTL-based immunotherapy. Tumor escape variants (TEV) recovered from the lungs of CTL-treated mice exhibited more aggressive behavior in vivo. However, these TEV retained relevant MHC class I and tumor Ag expression and sensitivity to CTL via the perforin pathway but reduced susceptibility to Fas-mediated lysis. Moreover, TEV were significantly less responsive to eradication by CTL adoptive immunotherapy paradigms as a consequence of increased Fas resistance. Overall, we identified that Faslow-TEV emerged as a direct consequence of CTL-tumor interactions in vivo, and that such an altered neoplastic Fas phenotype compromised immunotherapy efficacy. Together, these findings may have important implications for both tumor progression and the design of immunotherapeutic interventions to confront these selective pressures or escape mechanisms.
Alloantigen Affinity and CD4 Help Determine Severity of Graft-versus-Host Disease Mediated by CD8 Donor T Cells
Authors: Yu Xue-Zhong , Albert Michael H. , Anasetti Claudio 
Published: April 2014

Abstract
TCR affinity dictates T cell selection in the thymus and also has a high impact on the fate of peripheral T cells. Graft-vs-host disease (GVHD) is a pathological process initiated by activation of donor T cells after adoptive transfer into an allogeneic recipient. How TCR affinity affects the potential of alloreactive T cells to induce GVHD is unclear. Using alloreactive CD4+ and CD8+ TCR transgenic (Tg) T cells, GVHD models are presented that allow for the visualization of how CD8+ alloreactive T cells behave in response to alloantigens with different TCR affinity in the absence or presence of CD4 help. In a nonmyeloablative transplant model where GVHD lethality is due to marrow aplasia, alloreactive CD8+ TCR Tg T cells induced significantly more severe GVHD in the recipients that express an intermediate-affinity alloantigen than in the recipients that express a high-affinity alloantigen. In a myeloablative transplant model where GVHD lethality is due to epithelium injury, CD8+ TCR Tg cells were also more pathogenic in the recipients with an intermediate-affinity alloantigen than in those with a high-affinity alloantigen. The presence of alloreactive CD4+ TCR Tg cells enhanced the potential of CD8+ TCR Tg cells to cause GVHD in recipients with an intermediate-, but not with a high-, affinity alloantigen. These findings underscore that alloantigen affinity and CD4 help control the fate and pathogenicity of alloreactive CD8+ T cells in vivo.
The BZLF1 Homolog of an Epstein-Barr-Related γ-Herpesvirus Is a Frequent Target of the CTL Response in Persistently Infected Rhesus Macaques
Authors: Fogg Mark H. , Garry Deirdre , Awad Amany , Wang Fred , Kaur Amitinder 
Published: April 2014

AbstractAlthough CD8+ T lymphocytes targeting lytic infection proteins dominate the immune response to acute and persistent EBV infection, their role in immune control of EBV replication is not known. Rhesus lymphocryptovirus (rhLCV) is a γ-herpesvirus closely related to EBV, which establishes persistent infection in rhesus macaques. In this study, we investigated cellular immune responses to the rhLCV BZLF1 (rhBZLF1) homolog in a cohort of rhLCV-seropositive rhesus macaques. rhBZLF1-specific IFN-γ ELISPOT responses ranging between 56 and 3070 spot-forming cells/106 PBMC were detected in 36 of 57 (63%) rhesus macaques and were largely mediated by CD8+ T lymphocytes. The prevalence and magnitude of ELISPOT responses were greater in adult (5–15 years of age) rather than juvenile macaques (&lt;5 years of age), suggesting that rhBZLF1-specific CTL increase over time following early primary infection. A highly immunogenic region in the carboxyl terminus of the rhBZLF1 protein containing overlapping CTL epitopes restricted by Mamu-A*01 and other as yet unidentified MHC class I alleles was identified. The presence of a robust CD8+ T lymphocyte response targeting this lytic infection protein in both rhesus macaques and humans suggests that these CTL may be important for immune control of EBV-related γ-herpesvirus infection. These data underscore the utility of the rhLCV-macaque model for studies of EBV pathogenesis.
Role of Antigen-Processing Machinery in the In Vitro Resistance of Squamous Cell Carcinoma of the Head and Neck Cells to Recognition by CTL
Authors: López-Albaitero Andrés , Nayak Jayakar V. , Ogino Takeshi , Machandia Avinash , Gooding William , DeLeo Albert B. , Ferrone Soldano , Ferris Robert L. 
Published: April 2014

Abstract
Squamous cell carcinoma of the head and neck (SCCHN) cells are poorly recognized in vitro by CTL despite expressing the restricting HLA class I allele and the targeted tumor Ag (TA). Several lines of evidence indicate that the lack of SCCHN cell recognition by CTL reflects defects in targeted TA peptide presentation by HLA class I Ag to CTL because of Ag-processing machinery (APM) dysfunction. First, lack of recognition of SCCHN cells by CTL is associated with marked down-regulation of the IFN-γ-inducible APM components low-m.w. protein 2, TAP1, TAP2, and tapasin. Second, SCCHN cell recognition by CTL is restored by pulsing cells with exogenous targeted TA peptide. Third, the restoration of CTL recognition following incubation of SCCHN cells with IFN-γ is associated with a significant (p = 0.001) up-regulation of the APM components TAP1, TAP2, and tapasin. Lastly, and most conclusively, SCCHN cell recognition by CTL is restored by transfection with wild-type TAP1 cDNA. Our findings may explain the association between APM component down-regulation and poor clinical course of the disease in SCCHN. Furthermore, the regulatory nature of the APM defects in SCCHN cells suggests that intralesional administration of IFN-γ may have a beneficial effect on the clinical course of the disease and on T cell-based immunotherapy of SCCHN by restoring SCCHN cell recognition by CTL.
Induction of Alloreactive CD4 T Cell Tolerance in Molecular Chimeras: A Possible Role for Regulatory T Cells
Authors: Forman Daron , Kang Eun-Suk , Tian Chaorui , Paez-Cortez Jesus , Iacomini John 
Published: April 2014

Abstract
Induction of molecular chimerism following reconstitution of mice with autologous bone marrow cells expressing a retrovirally encoded allogeneic MHC class I Ag results in donor-specific tolerance. To investigate the mechanism by which CD4 T cells that recognize allogeneic MHC class I through the indirect pathway of Ag presentation are rendered tolerant in molecular chimeras, transgenic mice expressing a TCR on CD4 T cells specific for peptides derived from Kb were used. CD4 T cells expressing the transgenic TCR were detected in mice reconstituted with bone marrow cells transduced with retroviruses carrying the gene encoding H-2Kb, albeit detection was at lower levels than in mice receiving mock-transduced bone marrow. Despite the presence of CD4 T cells expressing an alloreactive TCR, mice receiving H-2Kb-transduced bone marrow permanently accepted Kb disparate skin grafts. CD4+CD25+ T cells from mice reconstituted with H-2Kb-transduced bone marrow prevented rejection of Kb disparate skin grafts when adoptively transferred into immunodeficient mice along with effector T cells, suggesting that induction of molecular chimerism leads to the generation of donor specific regulatory T cells, which may be involved in preventing alloreactive CD4 T cell responses that lead to rejection.
Combinations of CD45 Isoforms Are Crucial for Immune Function and Disease
Authors: Dawes Ritu , Petrova Svetla , Liu Zhe , Wraith David , Beverley Peter C. L. , Tchilian Elma Z. 
Published: April 2014

AbstractExpression of the CD45 Ag in hemopoietic cells is essential for normal development and function of lymphocytes, and both mice and humans lacking expression exhibit SCID. Human genetic variants of CD45, the exon 4 C77G and exon 6 A138G alleles, which alter the pattern of CD45 isoform expression, are associated with autoimmune and infectious diseases. We constructed transgenic mice expressing either an altered level or combination of CD45 isoforms. We show that the total level of CD45 expressed is crucial for normal TCR signaling, lymphocyte proliferation, and cytokine production. Most importantly, transgenic lines with a normal level, but altered combinations of CD45 isoforms, CD45RABC/+ and CD45RO/+ mice, which mimic variant CD45 expression in C77G and A138G humans, show more rapid onset and increased severity of experimental autoimmune encephalomyelitis. CD45RO/+ cells produce more TNF-α and IFN-γ. Thus, for the first time, we have shown experimentally that it is the combination of CD45 isoforms that affects immune function and disease.
Immunization with Murine Breast Cancer Cells Treated with Antisense Oligodeoxynucleotides to Type I Insulin-Like Growth Factor Receptor Induced an Antitumoral Effect Mediated by a CD8+ Response Involving Fas/Fas Ligand Cytotoxic Pathway
Authors: Schillaci Roxana , Salatino Mariana , Cassataro Juliana , Proietti Cecilia J. , Giambartolomei Guillermo H. , Rivas Martín A. , Carnevale Romina P. , Charreau Eduardo H. , Elizalde Patricia V. 
Published: April 2014

Abstract
We have demonstrated that in vivo administration of phosphorothioate antisense oligodeoxynucleotides (AS[S]ODNs) to type I insulin-like growth factor receptor (IGF-IR) mRNA resulted in inhibition of C4HD breast cancer growth in BALB/c mice. The present study focused on whether in vivo administration of C4HD tumor cells pretreated with IGF-IR AS[S]ODN and irradiated could provide protection against C4HD wild-type tumor challenge and also on elucidating the mechanism mediating this effect. Our results showed that mice immunized with IGF-IR AS[S]ODN-treated C4HD cells experienced a growth inhibition of 53.4%, 61.6%, and 60.2% when compared with PBS-treated mice, wild-type C4HD cell-injected mice, or phosphorothioate sense oligodeoxynucleotide-treated C4HD cell-injected mice, respectively. The protective effect was C4HD-specific, because no cross-protection was observed against other syngeneic mammary tumor lines. The lack of protection against tumor formation in nude mice indicated that T cells were involved in the antitumoral response. Furthermore, cytotoxicity and splenocyte proliferation assays demonstrated that a cellular CD8+-dependent immune response, acting through the Fas/Fas ligand death pathway, could be mediating the antitumor effect induced by immunization with AS[S]ODN-treated cells. Immunization also induced splenocytes to produce Ag-dependent IFN-γ, indicating the presence of a type 1 response. We demonstrated for the first time that IGF-IR AS[S]ODN treatment of breast cancer cells induced expression of CD86 and heat shock protein 70 molecules, both involved in the induction of the immunogenic phenotype. Immunization with these tumor immunogens imparted protection against parental tumor growth through activation of a specific immune response.
Differential MHC Class II Presentation of a Pathogenic Autoantigen during Health and Disease
Authors: Shih Fei F. , Racz Jennifer , Allen Paul M. 
Published: April 2014

Abstract
Glucose-6-phosphate isomerase (GPI) is the target autoantigen recognized by KRN T cells in the K/BxN model of rheumatoid arthritis. T cell reactivity to this ubiquitous Ag results in the recruitment of anti-GPI B cells and subsequent immune complex-mediated arthritis. Because all APCs have the capacity to process and present this autoantigen, it is unclear why systemic autoimmunity with polyclonal B cell activation does not ensue. To this end, we examined how GPI is presented by B cells relative to other immunologically relevant APCs such as dendritic cells (DCs) and macrophages in the steady state, during different phases of arthritis development, and after TLR stimulation. Although all APCs can process and present the GPI:I-Ag7 complex, they do so with different efficiencies. DCs are the most potent at baseline and become progressively more potent with disease development correlating with immune complex uptake. Interestingly, in vivo and in vitro maturation of DCs did not enhance GPI presentation, suggesting that DCs use mechanisms to regulate the presentation of self-peptides. Non-GPI-specific B cells are the weakest APCs (100-fold less potent than DCs) and fail to productively engage KRN T cells at steady state and during arthritis. However, the ability to stimulate KRN T cells is strongly enhanced in B cells after TLR ligation and provides a mechanism whereby polyclonal B cells may be activated in the wake of an acute infection.
Regulatory T Cells Can Mediate Their Function through the Stimulation of APCs to Produce Immunosuppressive Nitric Oxide
Authors: Chen Cyndi , Lee Wen-hui , Zhong Lingwen , Liu Chih-Pin 
Published: April 2014

Abstract
Regulatory T cells (Tr cells) play a critical role in inducing immune tolerance. It remains largely unclear how various types of Tr cells perform their regulatory function. We have studied the underlying regulatory mechanism of a population of autoantigen-specific CD4+ Tr cells. These T cells are specific for the glutamic acid decarboxylase p206–220 peptide and are isolated from the diabetes-resistant nonobese-resistant mice. Although these T cells express T-bet and display a Th1 phenotype, they are able to inhibit diabetes. Their regulatory function is dependent on both IFN-γ and cell contact with target cells. These Tr cells can mediate their cell contact-dependent regulatory function by secreting IFN-γ which stimulates APCs to produce NO. NO is necessary for the Tr cells to inhibit the proliferation of pathogenic T cells and the development of diabetes. Therefore, we have identified a novel mechanism by which these Tr cells can exert their regulatory function. These results also provide an explanation as to why IFN-γ may play both pathogenic and immunomodulatory roles in autoimmune diseases.
Superior Protective and Therapeutic Effects of IL-12 and IL-18 Gene-Transduced Dendritic Neuroblastoma Fusion Cells on Liver Metastasis of Murine Neuroblastoma
Authors: Iinuma Hisae , Okinaga Kota , Fukushima Ryoji , Inaba Tsuyoshi , Iwasaki Kota , Okinaga Akira , Takahashi Ichiro , Kaneko Michio 
Published: April 2014

Abstract
Fusion vaccine of dendritic cells (DCs) and tumor cells has the advantage of inducing an immune response against multiple tumor Ags, including unknown tumor Ags. Using the liver metastasis model of C1300 neuroblastoma cells, we assessed the protective and therapeutic effects of fusion cells transduced with the IL-12 gene and/or the IL-18 gene. Improving the fusion method by combining polyethylene glycol and electroporation increased loading efficiency. In the A/J mice vaccinated with fusion cells modified with the LacZ gene (fusion/LacZ), IFN-γ production and CTL activity increased significantly compared with that of DCs/LacZ, C1300/LacZ, or a mixture of the two (mixture/LacZ). With the transduction of IL-12 and IL-18 genes into the fusion cells (fusion/IL-12/IL-18), the level of IFN-γ increased more than five times that of other fusion groups. In addition, NK cell activity and CTL activity increased significantly compared with that of mixture/LacZ, fusion/LacZ, DC/LacZ, or C1300/LacZ. In the protective and therapeutic studies of fusion cell vaccine, mice vaccinated with fusion/LacZ, fusion/IL-12, fusion/IL-18, or fusion/IL-12/IL-18 showed a significant decrease in liver metastasis and a significant increase in survival compared with mice given a mixture/LacZ, DCs/LacZ, or C1300/LacZ. In particular, the mice receiving fusion/IL-12/IL-18 vaccine showed a complete protective effect and the highest therapeutic effects. The present study investigates the improved loading efficiency of fusion cells and suggests that the introduction of IL-12 and IL-18 genes can induce extremely strong protective and therapeutic effects on liver metastasis of neuroblastoma.
GATA-3 Directly Remodels the IL-10 Locus Independently of IL-4 in CD4+ T Cells
Authors: Shoemaker John , Saraiva Margarida , O’Garra Anne 
Published: April 2014

Abstract
IL-10 is a major regulator in inflammatory responses. Although various transcription factors were defined to enhance IL-10, the molecular mechanism for the initiation of Il-10 transcription, remains unknown. mRNA profiling of six distinct primary CD4+ T cell populations showed differential expression of the transcription factor GATA-3 correlated with levels of IL-10 expression. We showed that ectopic expression of GATA-3 in naive primary CD4+ T cells enhanced expression of IL-10 by these cells and uncovered a possible mechanism for this effect. We found that GATA-3 induced changes of the chromatin structure at the Il-10 locus and that these changes occur even in the absence of IL-4. Furthermore we found that in the presence of GATA-3 the histones at the Il-10 locus become acetylated. Despite being recruited in vivo to two locations on the Il-10 locus, GATA-3 did not transactivate the IL-10 promoter. We therefore suggest a key role of GATA-3 in instructing Il-10 gene expression in primary CD4+ T cells, possibly by switching and stabilizing the Il-10 locus into a transcriptionally competent status.