技术资料

Transfusion-related acute lung injury (TRALI) is a serious complication of transfusion and has been ranked as one of the leading causes of transfusion-related fatalities. Nonetheless,many details of the immunopathogenesis of TRALI,particularly with respect to recipient factors are unknown. We used a murine model of antibody-mediated TRALI in an attempt to understand the role that recipient lymphocytes might play in TRALI reactions. Intravenous injection of an IgG2a antimurine major histocompatibility complex class I antibody (34-1-2s) into BALB/c mice induced moderate hypothermia and pulmonary granulocyte accumulation but no pulmonary edema nor mortality. In contrast,34-1-2s injections into mice with severe combined immunodeficiency caused severe hypothermia,severe pulmonary edema,and approximately 40% mortality indicating a critical role for T and B lymphocytes in suppressing TRALI reactions. Adoptive transfer of purified CD8(+) T lymphocytes or CD4(+) T cells but not CD19(+) B cells into the severe combined immunodeficiency mice alleviated the antibody-induced hypothermia,lung damage,and mortality,suggesting that T lymphocytes were responsible for the protective effect. Taken together,these results suggest that recipient T lymphocytes play a significant role in suppressing antibody-mediated TRALI reactions. They identify a potentially new recipient mechanism that controls the severity of TRALI reactions. View Publication

BACKGROUND: Therapies directed at augmenting regulatory T cell (Treg) activities in vivo as a systemic treatment for autoimmune disorders and transplantation may be associated with significant off-target effects,including a generalized immunosuppression that may compromise beneficial immune responses to infections and cancer cells. Adoptive cellular therapies using purified expanded Tregs represents an attractive alternative to systemic treatments,with results from animal studies noting increased therapeutic potency of antigen-specific Tregs over polyclonal populations. However,current methodologies are limited in terms of the capacity to isolate and expand a sufficient quantity of endogenous antigen-specific Tregs for therapeutic intervention. Moreover,FOXP3+ Tregs fall largely within the CD4+ T cell subset and are thus routinely MHC class II-specific,whereas class I-specific Tregs may function optimally in vivo by facilitating direct tissue recognition. METHODOLOGY/PRINCIPAL FINDINGS: To overcome these limitations,we have developed a novel means for generating large numbers of antigen-specific Tregs involving lentiviral T cell receptor (TCR) gene transfer into in vitro expanded polyclonal natural Treg populations. Tregs redirected with a high-avidity class I-specific TCR were capable of recognizing the melanoma antigen tyrosinase in the context of HLA-A*0201 and could be further enriched during the expansion process by antigen-specific reactivation with peptide loaded artificial antigen presenting cells. These in vitro expanded Tregs continued to express FOXP3 and functional TCRs,and maintained the capacity to suppress conventional T cell responses directed against tyrosinase,as well as bystander T cell responses. Using this methodology in a model tumor system,murine Tregs designed to express the tyrosinase TCR effectively blocked antigen-specific effector T cell (Teff) activity as determined by tumor cell growth and luciferase reporter-based imaging. CONCLUSIONS/SIGNIFICANCE: These results support the feasibility of class I-restricted TCR transfer as a promising strategy to redirect the functional properties of Tregs and provide for a more efficacious adoptive cell therapy. View Publication

RATIONALE: Chitin is a ubiquitous polysaccharide in fungi,insects,allergens,and parasites that is released at sites of infection. Its role in the generation of tissue inflammation,however,is not fully understood. OBJECTIVES: We hypothesized that chitin is an important adjuvant for adaptive immunity. METHODS: Mice were injected with a solution of ovalbumin and chitin. MEASUREMENTS AND MAIN RESULTS: We used in vivo and ex vivo/in vitro approaches to characterize the ability of chitin fragments to foster adaptive immune responses against ovalbumin and compared these responses to those induced by aluminum hydroxide (alum). In vivo,ovalbumin challenge caused an eosinophil-rich pulmonary inflammatory response,Th2 cytokine elaboration,IgE induction,and mucus metaplasia in mice that had been sensitized with ovalbumin plus chitin or ovalbumin plus alum. Toll-like receptor-2,MyD88,and IL-17A played critical roles in the chitin-induced responses,and MyD88 and IL-17A played critical roles in the alum-induced responses. In vitro,CD4(+) T cells from mice sensitized with ovalbumin plus chitin were incubated with ovalbumin-stimulated bone marrow-derived dendritic cells. In these experiments,CD4(+) T-cell proliferation,IL-5,IL-13,IFN-γ,and IL-17A production were appreciated. Toll-like receptor-2,MyD88,and IL-17A played critical roles in these in vitro adjuvant properties of chitin. TLR-2 was required for cell proliferation,whereas IL-17 and TLR-2 were required for cytokine elaboration. IL-17A also inhibited the generation of adaptive Th1 responses. CONCLUSIONS: These studies demonstrate that chitin is a potent multifaceted adjuvant that induces adaptive Th2,Th1,and Th17 immune responses. They also demonstrate that the adjuvant properties of chitin are mediated by a pathway(s) that involves and is regulated by TLR-2,MyD88,and IL-17A. View Publication

Events defining the progression to human type 1 diabetes (T1D) have remained elusive owing to the complex interaction between genetics,the immune system,and the environment. Type 1 interferons (T1-IFN) are known to be a constituent of the autoinflammatory milieu within the pancreas of patients with T1D. However,the capacity of IFNα/β to modulate human activated autoreactive CD8+ T-cell (cytotoxic T lymphocyte) responses within the islets of patients with T1D has not been investigated. Here,we engineer human β-cell-specific cytotoxic T lymphocytes and demonstrate that T1-IFN augments cytotoxicity by inducing rapid phosphorylation of STAT4,resulting in direct binding at the granzyme B promoter within 2 h of exposure. The current findings provide novel insights concerning the regulation of effector function by T1-IFN in human antigen-experienced CD8+ T cells and provide a mechanism by which the presence of T1-IFN potentiates diabetogenicity within the autoimmune islet. View Publication

V-domain immunoglobulin suppressor of T cell activation (VISTA) is a recently discovered immune checkpoint ligand that functions to suppress T cell activity. The therapeutic potential of activating this immune checkpoint pathway to reduce inflammatory responses remains untapped,largely due to the inability to derive agonists targeting its unknown receptor. A dimeric construct of the IgV domain of VISTA (VISTA-Fc) was shown to suppress the activation of T cells in vitro. However,this effect required its immobilization on a solid surface,suggesting that VISTA-Fc may display limited efficacy as a VISTA-receptor agonist in vivo. Herein,we have designed a stable pentameric VISTA construct (VISTA.COMP) by genetically fusing its IgV domain to the pentamerization domain from the cartilage oligomeric matrix protein (COMP). In contrast to VISTA-Fc,VISTA.COMP does not require immobilization to inhibit the proliferation of CD4+ T cells undergoing polyclonal activation. Furthermore,we show that VISTA.COMP,but not VISTA-Fc,functions as an immunosuppressive agonist in vivo capable of prolonging the survival of skin allografts in a mouse transplant model as well as rescuing mice from acute concanavalin-A-induced hepatitis. Collectively,we believe our data demonstrate that VISTA.COMP is a checkpoint receptor agonist and the first agent to our knowledge targeting the putative VISTA-receptor to suppress T cell-mediated immune responses. View Publication