Therapeutic effects of anti-GM2 CAR-T cells expressing IL-7 and CCL19 for GM2-positive solid cancer in xenograft model.

BACKGROUND: While chimeric antigen receptor (CAR)-T cell therapy has demonstrated excellent efficacy in hematopoietic malignancies, its clinical application in solid cancers has yet to be achieved. One of the reasons for such hurdle is a lack of suitable CAR targets in solid cancers. METHODS: GM2 is one of the gangliosides, a group of glycosphingolipids with sialic acid in the glycan, and overexpressed in various types of solid cancers. In this study, by using interleukin (IL)-7 and chemokine (C-C motif) ligand 19 (CCL19)-producing human CAR-T system which we previously developed, a possibility of GM2 as a solid tumor target for CAR-T cell therapy was explored in a mouse model with human small-cell lung cancer. RESULTS: Treatment with anti-GM2 IL-7/CCL19-producing CAR-T cells induced complete tumor regression along with an abundant T cell infiltration into the solid tumor tissue and long-term memory responses, without any detectable adverse events. In addition, as measures to control cytokine-release syndrome and neurotoxicity which could occur in association with clinical use of CAR-T cells, we incorporated Herpes simplex virus-thymidine kinase (HSV-TK), a suicide system to trigger apoptosis by administration of ganciclovir (GCV). HSV-TK-expressing anti-GM2 IL-7/CCL19-producing human CAR-T cells were efficiently eliminated by GCV administration in vivo. CONCLUSIONS: Our study revealed the promising therapeutic efficacy of anti-GM2 IL-7/CCL19-producing human CAR-T cells with an enhanced safety for clinical application in the treatment of patients with GM2-positive solid cancers.

Novel technologies for improving the safety and efficacy of CAR-T cell therapy.

Chimeric antigen receptor-T (CAR-T) cell therapy has shown significant therapeutic efficacy in the treatment of hematological B-cell malignancies. However, the efficacy of CAR-T cell therapy against solid tumors is limited due to the heterogeneity of tumor antigens and the immunosuppressive tumor microenvironment. Therefore, there is strong demand for novel technologies to improve the efficacy of CAR-T cell therapy. In addition, as CAR-T cells often cause severe side effects, systems to control the activity of CAR-T cells so as to avoid or lessen the occurrence and intensity of these side effects are needed. Here, we describe recently emerging approaches to enhance and/or regulate CAR-T cell functions. These approaches have led to the development of CAR-T therapies with improved efficacy and safety, which are expected to be clinically applied to a variety of cancer types in combination with other therapies, such as immune checkpoint inhibitors, chemotherapy, molecular targeted drugs, and radiation therapy.

Enhanced Antitumor Responses of Tumor Antigen-Specific TCR T Cells Genetically Engineered to Produce IL7 and CCL19.

Although adoptive transfer of T cells genetically engineered to express chimeric antigen receptor (CAR) or T-cell receptor (TCR) has been actively developed and applied into clinic recently, further improvement of these modalities is highly demanded, especially in terms of its efficacy. Because we previously revealed the profound enhancement of antitumor effects of CAR T cells by concomitant expression of IL7 and CCL19, this study further explored a potential of IL7/CCL19 production technology to augment antitumor effects of TCR T cells. IL7/CCL19-producing P1A tumor antigen-specific TCR T cells (7 × 19 P1A T cells) demonstrated significantly improved antitumor effects, compared with those without IL7/CCL19 production, and generated long-term memory responses. The antitumor effects of 7×19 P1A T cells were further upregulated by combination with anti-PD-1 antibody, in which blockade of PD-1 signal in both 7×19 P1A T cells and endogenous T cells plays an important role. Taken together, our study demonstrated that concomitant production of IL7 and CCL19 by genetically engineered tumor-reactive T cells could synergize with PD-1 blockade therapy to generate potent and long-lasting antitumor immunity.

Anti-tumor efficacy of human anti-c-met CAR-T cells against papillary renal cell carcinoma in an orthotopic model.

Chimeric antigen receptor (CAR)-T cell therapy has shown salient efficacy in cancer immunotherapy, particularly in the treatment of B cell malignancies. However, the efficacy of CAR-T for solid tumors remains inadequate. In this study, we displayed that c-met is an appropriate therapeutic target for papillary renal cell carcinoma (PRCC) using clinical samples, developed an anti-human c-met CAR-T cells, and investigated the anti-tumor efficacy of the CAR-T cells using an orthotopic mouse model as pre-clinical research. Administration of the anti-c-met CAR-T cells induced marked infiltration of the CAR-T cells into the tumor tissue and unambiguous suppression of tumor growth. Furthermore, in combination with axitinib, the anti-tumor efficacy of the CAR-T cells was synergistically augmented. Taken together, our current study demonstrated the potential for clinical application of anti-c-met CAR-T cells in the treatment of patients with PRCC.

Enhanced anti-tumor efficacy of IL-7/CCL19-producing human CAR-T cells in orthotopic and patient-derived xenograft tumor models.

Chimeric antigen receptor (CAR)-T cell therapy has impressive efficacy in hematological malignancies, but its application in solid tumors remains a challenge. Multiple hurdles associated with the biological and immunological features of solid tumors currently limit the application of CAR-T cells in the treatment of solid tumors. Using syngeneic mouse models, we recently reported that CAR-T cells engineered to concomitantly produce interleukin (IL)-7 and chemokine (C-C motif) ligand 19 (CCL19)-induced potent anti-tumor efficacy against solid tumors through an improved ability of migration and proliferation even in an immunosuppressive tumor microenvironment. In this study, for a preclinical evaluation preceding clinical application, we further explored the potential of IL-7/CCL19-producing human CAR-T cells using models that mimic the clinical features of solid tumors. Human anti-mesothelin CAR-T cells producing human IL-7/CCL19 achieved complete eradication of orthotopic pre-established malignant mesothelioma and prevented a relapse of tumors with downregulated antigen expression. Moreover, mice with patient-derived xenograft of mesothelin-positive pancreatic cancers exhibited significant inhibition of tumor growth and prolonged survival following treatment with IL-7/CCL19-producing CAR-T cells, compared to treatment with conventional CAR-T cells. Transfer of IL-7/CCL19-producing CAR-T cells resulted in an increase in not only CAR-T cells but also non-CAR-T cells within the tumor tissues and downregulated the expression of exhaustion markers, including PD-1 and TIGIT, on the T cells. Taken together, our current study elucidated the exceptional anti-tumor efficacy of IL-7/CCL19-producing human CAR-T cells and their potential for clinical application in the treatment of patients with solid tumors.

Improved survival of chimeric antigen receptor-engineered T (CAR-T) and tumor-specific T cells caused by anti-programmed cell death protein 1 single-chain variable fragment-producing CAR-T cells.

Chimeric antigen receptor-engineered T (CAR-T)-cell therapy holds significant promise for the treatment of hematological malignancies, especially for B-cell leukemia and lymphoma. However, its efficacy against non-hematological malignancies has been limited as a result of several biological problems characteristic of the tumor microenvironment of solid tumors. One of the main hurdles is the heterogeneous nature of tumor-associated antigens (TAA) expressed in solid tumors. Another hurdle is the inefficient activation and limited persistence of CAR-T cells, mainly as a result of T-cell exhaustion caused by immunosuppressive factors in the tumor microenvironment. In the present study, to address these problems, we engineered CAR-T cells to produce antagonistic anti-programmed cell death protein 1 (PD-1) single-chain variable fragment (scFv), by which PD-1-dependent inhibitory signals in CAR-T cells and adjacent tumor-specific non-CAR-T cells are attenuated. In mouse solid tumor models, PD-1 scFv-producing CAR-T cells induced potent therapeutic effects superior to those of conventional CAR-T cells, along with a significant reduction of apoptotic cell death not only in CAR-T cells themselves but also in TAA-specific T cells in the tumor tissue. In addition, the treatment with anti-PD-1 scFv-producing CAR-T cells resulted in an increased concentration of PD-1 scFv in tumor tissue but not in sera, suggesting an induction of less severe systemic immune-related adverse events. Hence, the present study developed anti-PD-1 scFv-producing CAR-T cell technology and explored its cellular mechanisms underlying potent antitumor efficacy.

Inhibitory functions of PD-L1 and PD-L2 in the regulation of anti-tumor immunity in murine tumor microenvironment.

Although a role of PD-L1 in the suppression of anti-tumor immunity and its value as a predictive biomarker has been suggested by various preclinical and clinical studies, the precise mechanisms how PD-L1 and PD-L2, another ligand of PD-1, regulate anti-tumor immunity in the tumor microenvironment are yet to be fully explored. Here, we address this issue using PD-L1-deficient tumor cells, PD-L1-knockout (KO) mice, anti-PD-L1 monoclonal antibody (mAb), and anti-PD-L2 mAb. Firstly, PD-L1-deficient or competent tumor cells were inoculated into wild-type or PD-L1-KO mice. Results of tumor growth and mouse survival indicated that both tumor- and host-derived PD-L1 are functional to suppress anti-tumor immunity, while the former contributes predominantly than the latter. Experiments using bone marrow (BM) chimeric mice, generated by transferring PD-L1-KO BM cells into wild-type mice or vice versa, further suggested that PD-L1 expressed on BM-derived hematopoietic cells mediates the suppressive effects on anti-tumor immunity. Secondly, anti-PD-L2 mAb treatment demonstrated a profound synergy with anti-PD-L1 mAb therapy, whereas anti-PD-L2 mAb alone hardly induced any anti-tumor effects, suggesting that PD-L2's function becomes evident when the effects of PD-L1 are abrogated by anti-PD-L1 mAb. Consistent with this notion, PD-L2 expression was upregulated on tumor-associated macrophages (TAM) when mice were treated with anti-PD-L1 mAb. Taken together, our study elucidated the importance of PD-L1 associated with tumor cells and non-tumor host cells, particularly BM-derived hematopoietic cells, as well as PD-L2 inducibly expressed on TAM in the suppression of anti-tumor immunity in the tumor microenvironment.

IL-7 and CCL19 expression in CAR-T cells improves immune cell infiltration and CAR-T cell survival in the tumor.

Infiltration, accumulation, and survival of chimeric antigen receptor T (CAR-T) cells in solid tumors is crucial for tumor clearance. We engineered CAR-T cells to express interleukin (IL)-7 and CCL19 (7 × 19 CAR-T cells), as these factors are essential for the maintenance of T-cell zones in lymphoid organs. In mice, 7 × 19 CAR-T cells achieved complete regression of pre-established solid tumors and prolonged mouse survival, with superior anti-tumor activity compared to conventional CAR-T cells. Histopathological analyses showed increased infiltration of dendritic cells (DC) and T cells into tumor tissues following 7 × 19 CAR-T cell therapy. Depletion of recipient T cells before 7 × 19 CAR-T cell administration dampened the therapeutic effects of 7 × 19 CAR-T cell treatment, suggesting that CAR-T cells and recipient immune cells collaborated to exert anti-tumor activity. Following treatment of mice with 7 × 19 CAR-T cells, both recipient conventional T cells and administered CAR-T cells generated memory responses against tumors.

Chimeric antigen receptor (CAR)-T cell therapy.

Chimeric antigen receptor (CAR)-T cell therapy, where patients' own T cells are engi- neered to express receptor that targets antigen found on the surface of cancer cells, delivers outstanding efficacy to treat hematological malignancies. This personalized medicine has been actively explored by researchers in academia and quickly developed for clinical applica- tion by several pharmaceutical/biotech companies. While CAR-T cell therapy is a highly promising technology, many challenges remain to be overcome in targeting solid tumors, in- cluding on-target off-tumor toxicity, inefficient accumulation and survival of CAR-T cells in the immunosuppressive tumor microenvironment. In this review, we briefly describe the cur- rent status, challenges, and future perspectives of CAR-T cell therapy.

Combined adjuvants of poly(I:C) plus LAG-3-Ig improve antitumor effects of tumor-specific T cells, preventing their exhaustion.

Therapeutic cancer vaccines are designed to treat cancer by boosting the endogenous immune system to fight against the cancer. In the development of clinically effective cancer vaccines, one of the most practical objectives is to identify adjuvants that are capable of optimizing the vaccine effects. In this study, we explored the potential of polyinosinic-polycytidylic acid (poly(I:C)) and LAG-3-Ig (soluble recombinant protein of lymphocyte activation gene-3 [LAG-3] extracellular domain fused with human IgG Fc region) as adjuvants for P1A tumor antigen peptide vaccine in a pre-established P815 mouse tumor model with a transfer of tumor-specific T cells. Whereas the use of poly(I:C) or LAG-3-Ig as a signal adjuvant induced a slight enhancement of P1A vaccine effects compared to incomplete Freund's adjuvant, combined treatment with poly(I:C) plus LAG-3-Ig remarkably potentiated antitumor effects, leading to complete rejection of pre-established tumor and long-term survival of mice. The potent adjuvant effects of poly(I:C) plus LAG-3-Ig were associated with an enhanced infiltration of T cells in the tumor tissues, and an increased proliferation and Th1-type cytokine production of tumor-reactive T cells. Importantly, the combined adjuvant of poly(I:C) plus LAG-3-Ig downregulated expressions of PD-1, LAG-3, and TIGIT on P1A-specific T cells, indicating prevention of T cell exhaustion. Taken together, the results of the current study show that the combined adjuvants of poly(I:C) plus LAG-3-Ig with tumor peptide vaccine induce profound antitumor effects by activating tumor-specific T cells.

Pathogenic Function of Herpesvirus Entry Mediator in Experimental Autoimmune Uveitis by Induction of Th1- and Th17-Type T Cell Responses.

Herpesvirus entry mediator (HVEM), a member of the TNFR superfamily, serves as a unique molecular switch to mediate both stimulatory and inhibitory cosignals, depending on its functions as a receptor or ligand interacting with multiple binding partners. In this study, we explored the cosignaling functions of HVEM in experimental autoimmune uveitis (EAU), a mouse model resembling human autoimmune uveitis conditions such as ocular sarcoidosis and Behcet disease. Our studies revealed that EAU severity significantly decreased in HVEM-knockout mice compared with wild-type mice, suggesting that stimulatory cosignals from the HVEM receptor are predominant in EAU. Further studies elucidated that the HVEM cosignal plays an important role in the induction of both Th1- and Th17-type pathogenic T cells in EAU, including differentiation of IL-17-producing αß(+)γδ(-) conventional CD4(+) T cells. Mice lacking lymphotoxin-like, inducible expression, competes with herpes simplex virus glycoprotein D for HVEM, a receptor expressed by T lymphocytes : LIGHT), B- and T-lymphocyte attenuator (BTLA) or both LIGHT and BTLA are also less susceptible to EAU, indicating that LIGHT-HVEM and BTLA-HVEM interactions, two major molecular pathways mediating HVEM functions, are both important in determining EAU pathogenesis. Finally, blocking HVEM cosignals by antagonistic anti-HVEM Abs ameliorated EAU. Taken together, our studies revealed a novel function of the HVEM cosignaling molecule and its ligands in EAU pathogenesis through the induction of Th1- and Th17-type T cell responses and suggested that HVEM-related molecular pathways can be therapeutic targets in autoimmune uveitis.

Dietary Omega-3 Fatty Acids Suppress Experimental Autoimmune Uveitis in Association with Inhibition of Th1 and Th17 Cell Function.

Omega (ω)-3 long-chain polyunsaturated fatty acids (LCPUFAs) inhibit the production of inflammatory mediators and thereby contribute to the regulation of inflammation. Experimental autoimmune uveitis (EAU) is a well-established animal model of autoimmune retinal inflammation. To investigate the potential effects of dietary intake of ω-3 LCPUFAs on uveitis, we examined the anti-inflammatory properties of these molecules in comparison with ω-6 LCPUFAs in a mouse EAU model. C57BL/6 mice were fed a diet containing ω-3 LCPUFAs or ω-6 LCPUFAs for 2 weeks before as well as after the induction of EAU by subcutaneous injection of a fragment of human interphotoreceptor retinoid-binding protein emulsified with complete Freund's adjuvant. Both clinical and histological scores for uveitis were smaller for mice fed ω-3 LCPUFAs than for those fed ω-6 LCPUFAs. The concentrations of the T helper 1 (Th1) cytokine interferon-γ and the Th17 cytokine interleukin-17 in intraocular fluid as well as the production of these cytokines by lymph node cells were reduced for mice fed ω-3 LCPUFAs. Furthermore, the amounts of mRNAs for the Th1- and Th17-related transcription factors T-bet and RORγt, respectively, were reduced both in the retina and in lymph node cells of mice fed ω-3 LCPUFAs. Our results thus show that a diet enriched in ω-3 LCPUFAs suppressed uveitis in mice in association with inhibition of Th1 and Th17 cell function.

Vγ2Vδ2 T cell Costimulation Increases NK cell Killing of Monocyte-derived Dendritic Cells.

Interactions between NK and dendritic cells (DC) affect maturation and function of both cell populations, including NK killing of DC (editing) that is important for controlling the quality of immune responses. We also know that antigen-stimulated Vγ2Vδ2 T cells costimulate NK cells via 4-1BB to enhance killing of tumor cell lines but we do not know what regulates 4-1BB expression or whether other NK effector functions including DC killing, might also be influenced by NK:γδ T cell cross talk. Here we show that antigen-stimulated γδ T cells costimulate NK through ICOS:ICOSL and this signal increases NK killing of autologous DC. Effects of NK:γδ T cell co-culture, which could be reproduced with soluble ICOS-Fc fusion protein, included increased CD69 and 4-1BB expression, IFN-γ, TNF-α, MIP-1ß, I-309, RANTES and sFasL production, as well as elevated mRNA levels for costimulatory receptors OX40 (TNFRSF4) and GITR (TNFRSF18). Thus, ICOS/ICOSL costimulation of NK by Vγ2Vδ2 T cells had broad effects on NK phenotype and effector functions. The NK γδ T cell cross talk links innate and antigen-specific lymphocyte responses in the control of cytotoxic effector function and dendritic cell killing. This article is protected by copyright. All rights reserved.

Redirecting gene-modified T cells toward various cancer types using tagged antibodies.

PURPOSE: To develop an adaptable gene-based vector that will confer immune cell specificity to various cancer types. EXPERIMENTAL DESIGN: Human and mouse T cells were genetically engineered to express a chimeric antigen receptor (CAR) that binds a fluorescein isothiocyanate (FITC) molecule, termed anti-FITC CAR T cells. Various antibodies (Ab) currently in clinical use including cetuximab (Ctx), trastuzumab (Her2), and rituximab (Rtx) were conjugated with FITC and tested for their ability to bind tumor cells, activate T cells, and induce antitumor effects in vitro and in vivo. RESULTS: Anti-FITC CAR T cells recognize various cancer types when bound with FITC-labeled Abs resulting in efficient target lysis, T-cell proliferation, and cytokine/chemokine production. The treatment of immunocompromised mice with human anti-FITC CAR T cells plus FITC-labeled cetuximab (FITC-Ctx) delayed the growth of colon cancer but unexpectedly led to the outgrowth of EGF receptor (EGFR)-negative tumor cells. On the other hand, in a human pancreatic cancer cell line with uniform EGFR expression, anti-FITC CAR T cells plus FITC-Ctx eradicated preestablished late-stage tumors. In immunocompetent mice, anti-FITC CAR T cells exhibited potent antitumor activity against syngeneic mouse breast cancer expressing Her2 and B-cell lymphoma expressing CD20 by combining with FITC-Her2 and FITC-Rtx, respectively. In addition, the activity of anti-FITC CAR T cells could be attenuated by subsequent injections of nonspecific FITC-IgG. CONCLUSION: These studies highlight an applicability of anti-tag CAR technology to treat patients with different types of cancers and a possibility to regulate CAR T-cell functions with competing FITC molecules.

Fully recombinant IgG2a Fc multimers (stradomers) effectively treat collagen-induced arthritis and prevent idiopathic thrombocytopenic purpura in mice.

INTRODUCTION: Soluble immune aggregates bearing intact Fc fragments are effective treatment for a variety of autoimmune disorders in mice. The better to understand the mechanisms by which Fc-bearing immune complexes suppress autoimmunity, and to develop a platform for clinical translation, we created a series of fully recombinant forms of polyvalent IgG2a Fc, termed stradomers, and tested their efficacy in a therapeutic model of collagen-induced arthritis (CIA) and preventive models of both idiopathic thrombocytopenic purpura (ITP) and graft-versus-host disease (GVHD). METHODS: Stradomers were created by engineering either the human IgG2 hinge sequence (IgG2H) or the isoleucine zipper (ILZ) onto either the carboxy or amino termini of murine IgG2a Fc. Multimerization and binding to the canonical Fc receptors and the C-type lectin SIGN-RI were evaluated by using sodium dodecylsulfate-polymerase chain reaction (SDS-PAGE) and Biacore/Octet assays. The efficacy of stradomers in alleviating CIA and preventing ITP and GVHD was compared with "gold standard" therapies, including prednisolone and intravenous immune globulin (IVIG). RESULTS: Stradomers exist as both homodimeric and highly ordered sequential multimers. Higher-order multimers demonstrate increasingly stable associations with the canonic Fcγ receptors (FcγRs), and SIGN-R1, and are more effective than Fc homodimers in treating CIA. Furthermore, stradomers confer partial protection against platelet loss in a murine model ITP, but do not prevent GVHD. CONCLUSION: These data suggest that fully human stradomers might serve as valuable tools for the treatment of selected autoimmune disorders and as reagents to study the function of Fc:FcR interactions in vivo.

Expression of anti-HVEM single-chain antibody on tumor cells induces tumor-specific immunity with long-term memory.

Genetic engineering of tumor cells to express immune-stimulatory molecules, including cytokines and co-stimulatory ligands, is a promising approach to generate highly efficient cancer vaccines. The co-signaling molecule, LIGHT, is particularly well suited for use in vaccine development as it delivers a potent co-stimulatory signal through the Herpes virus entry mediator (HVEM) receptor on T cells and facilitates tumor-specific T cell immunity. However, because LIGHT binds two additional receptors, lymphotoxin ß receptor and Decoy receptor 3, there are significant concerns that tumor-associated LIGHT results in both unexpected adverse events and interference with the ability of the vaccine to enhance antitumor immunity. In order to overcome these problems, we generated tumor cells expressing the single-chain variable fragment (scFv) of anti-HVEM agonistic mAb on the cell surface. Tumor cells expressing anti-HVEM scFv induce a potent proliferation and cytokine production of co-cultured T cells. Inoculation of anti-HVEM scFv-expressing tumor results in a spontaneous tumor regression in CD4+ and CD8+ T cell-dependent fashion, associated with the induction of tumor-specific long-term memory. Stimulation of HVEM and 4-1BB co-stimulatory signals by anti-HVEM scFv-expressing tumor vaccine combined with anti-4-1BB mAb shows synergistic effects which achieve regression of pre-established tumor and T cell memory specific to parental tumor. Taken in concert, our data suggest that genetic engineering of tumor cells to selectively potentiate the HVEM signaling pathway is a promising antitumor vaccine therapy.

Herpesvirus entry mediator regulates hypoxia-inducible factor-1α and erythropoiesis in mice.

Erythropoiesis, the production of red blood cells, must be tightly controlled to ensure adequate oxygen delivery to tissues without causing thrombosis or stroke. Control of physiologic and pathologic erythropoiesis is dependent predominantly on erythropoietin (EPO), the expression of which is regulated by hypoxia-inducible factor (HIF) activity in response to low oxygen tension. Accumulating evidence indicates that oxygen-independent mediators, including inflammatory stimuli, cytokines, and growth factors, also upregulate HIF activity, but it is unclear whether these signals also result in EPO production and erythropoiesis in vivo. Here, we found that signaling through herpesvirus entry mediator (HVEM), a molecule of the TNF receptor superfamily, promoted HIF-1α activity in the kidney and subsequently facilitated renal Epo production and erythropoiesis in vivo under normoxic conditions. This Epo upregulation was mediated by increased production of NO by renal macrophages. Hvem-deficient mice displayed impaired Epo expression and aggravated anemia in response to erythropoietic stress. These data reveal that HVEM signaling functions to promote HIF-1α activity and Epo production, and thus to regulate erythropoiesis. Furthermore, our findings suggest that this molecular mechanism could represent a therapeutic target for Epo-responsive diseases, including anemia.

Dichotomous regulation of GVHD through bidirectional functions of the BTLA-HVEM pathway.

B and T lymphocyte attenuator (BTLA) is a co-inhibitory receptor that interacts with herpesvirus entry mediator (HVEM), and this interaction regulates pathogenesis in various immunologic diseases. In graft-versus-host disease (GVHD), BTLA unexpectedly mediates positive effects on donor T-cell survival, whereas immunologic mechanisms of this function have yet to be explored. In this study, we elucidated a role of BTLA in GVHD by applying the newly established agonistic anti-BTLA monoclonal antibody that stimulates BTLA signal without antagonizing BTLA-HVEM interaction. Our results revealed that provision of BTLA signal inhibited donor antihost T-cell responses and ameliorated GVHD with a successful engraftment of donor hematopoietic cells. These effects were dependent on BTLA signal into donor T cells but neither donor non-T cells nor recipient cells. On the other hand, expression of BTLA mutant lacking an intracellular signaling domain restored impaired survival of BTLA-deficient T cells, suggesting that BTLA also serves as a ligand that delivers HVEM prosurvival signal in donor T cells. Collectively, current study elucidated dichotomous functions of BTLA in GVHD to serve as a costimulatory ligand of HVEM and to transmit inhibitory signal as a receptor.

Preventive and therapeutic potential of placental extract in contact hypersensitivity.

Immunoregulatory effects of placental extract and placenta-derived factors have been demonstrated in various conditions. Accordingly, placental extract has been used as certain types of medical intervention in Asian countries, whereas experimental evidence supporting its therapeutic effects and mechanisms has yet to be fully demonstrated. In this study, we investigate preventive and therapeutic effects of placental extract in contact hypersensitivity (CHS), a mouse model of allergic contact dermatitis. Administration of placental extract prior to the sensitization of allergic antigen (Ag) significantly inhibited the severity of CHS induced by Ag challenge. This effect was associated with reduced numbers of CD4(+) T cells in peripheral blood, decrease of tissue-infiltrating lymphocytes, and preferential production of Th2-type cytokines in Ag-challenged sites. In addition, CHS caused by repetitive challenges of allergic Ag was also prevented and treated by administration of placental extract. Finally, administration of cyclo-trans-4-L-hydroxyprolyl-L-serine, a dipeptide derived from placental extract, also alleviated CHS, suggesting its potential role in the effects of placental extract in CHS. Taken together, our findings demonstrated experimental evidence supporting immunoregulatory effects of placental extract in allergic skin diseases and elucidated its potential mechanisms.