Anti-TIM-3 Antibody Prevents Lymphocyte Apoptosis and Enhances Dendritic Cell Cancer Therapy

Currently, there is a strong unmet need for a new intervention therapy for hepatocellular carcinoma (HCC). One candidate therapy uses dendritic cells (DCs), which are professional antigen-presenting cells that are characterized by their potent ability to elicit immune responses to foreign antigens. DCs may be attractive adjuvant agents for cancer therapy but the effect of DCs therapy is restricted because of the immunosuppressive nature of the tumor microenvironment. T-cell immunoglobulin and mucin protein-3 (TIM-3) is a marker of this immunosuppressive tumor environment. Interaction of TIM-3 with its ligand, galectin 9, triggers cell death in activated T cells. In this study, we evaluated the antitumor effects of DC vaccine therapy in combination with TIM-3 blockade in a murine HCC system. In an animal cancer prevention model, BALB/c mice were immunized with DCs with or without anti-TIM-3 antibody before challenging with HCC tumor cells (BNL). In an animal cancer therapeutic model, BALB/c mice were inoculated with DCs with or without anti-TIM-3 antibody 10 days after injection with BNL cells. The mechanism of this combination therapy was investigated using immunohistologic staining of the treated tumors and flow cytometry of lymphocytes. DC and anti-TIM-3 antibody combination treatment prevented tumor development to a greater extent than DCs alone. In the therapeutic model, the outgrowth of the established tumors was significantly reduced in mice treated with the combination of DCs and anti-TIM-3 antibody. Immunohistological analyses of the therapeutic model showed marked infiltration of CD4+ cells and CD8+ T-cells in the established BNL tumors of mice treated with both DCs and anti-TIM-3 antibody. Anti-TIM-3 antibody treatment reduces lymphocyte apoptosis and enhances the antitumor effect of DC therapy in a murine HCC model

Effects of Interleukin-4-Transduced Tumor Cell Vaccines and Blockade of Programmed Cell Death 1 on the Growth of Established Tumors

Interleukin (IL)-4 exhibits strong antitumor effects and IL-4 gene therapy has been used clinically in the treatment of some types of cancer. In the present study, we evaluated the efficacy of IL-4-transduced tumor cell vaccines in combination with blockade of programmed cell death 1 (PD-1) and investigated the mechanisms underlying the antitumor effects of this therapy. A poorly immunogenic murine colorectal cancer cell line (i.e. MC38) was transduced to overexpress IL-4. In a therapeutic model, MC38-IL4 cells and anti-PD-1 antagonistic antibodies (Ab) were inoculated into parental tumor-bearing mice. Immunohistochemical analyses and tumor-specific lysis were also performed. Additive antitumor effects were observed when mice were treated with IL-4 in combination with an anti-PD-1 Ab. Immunohistochemical analysis of the therapeutic model showed marked infiltration of CD4+ and CD8+ cells into established MC38 tumors of mice treated with anti-PD-1 Ab. Significant tumor-specific cytolysis was detected when the splenocytes of mice treated with both IL-4 and anti-PD-1 Ab were used as effector cells. These results suggest that blockade of the interaction between PD-1 and programmed death ligand 1 (PD-L1) enhances the antitumor immune responses induced by IL-4. Thus, IL-4 gene-transduced tumor cell vaccines in combination with PD-1 blockade may be considered as possible candidates for clinical trials of new cancer vaccines

Transcriptional Activation of Low-Density Lipoprotein Receptor Gene by DJ-1 and Effect of DJ-1 on Cholesterol Homeostasis

DJ-1 is a novel oncogene and also causative gene for familial Parkinson’s disease park7. DJ-1 has multiple functions that include transcriptional regulation, anti-oxidative reaction and chaperone and mitochondrial regulation. For transcriptional regulation, DJ-1 acts as a coactivator that binds to various transcription factors, resulting in stimulation or repression of the expression of their target genes. In this study, we found the low-density lipoprotein receptor (LDLR) gene is a transcriptional target gene for DJ-1. Reduced expression of LDLR mRNA and protein was observed in DJ-1-knockdown cells and DJ-1-knockout mice and this occurred at the transcription level. Reporter gene assays using various deletion and point mutations of the LDLR promoter showed that DJ-1 stimulated promoter activity by binding to the sterol regulatory element (SRE) with sterol regulatory element binding protein (SREBP) and that stimulating activity of DJ-1 toward LDLR promoter activity was enhanced by oxidation of DJ-1. Chromatin immunoprecipitation, gel-mobility shift and co-immunoprecipitation assays showed that DJ-1 made a complex with SREBP on the SRE. Furthermore, it was found that serum LDL cholesterol level was increased in DJ-1-knockout male, but not female, mice and that the increased serum LDL cholesterol level in DJ-1-knockout male mice was cancelled by administration with estrogen, suggesting that estrogen compensates the increased level of serum LDL cholesterol in DJ-1-knockout female mice. This is the first report that DJ-1 participates in metabolism of fatty acid synthesis through transcriptional regulation of the LDLR gene

Immune Response of Cytotoxic T Lymphocytes and Possibility of Vaccine Development for Hepatitis C Virus Infection

Immune responses of cytotoxic T lymphocytes (CTLs) are implicated in viral eradication and the pathogenesis of hepatitis C. Weak CTL response against hepatitis C virus (HCV) may lead to a persistent infection. HCV infection impairs the function of HCV-specific CTLs; HCV proteins are thought to actively suppress host immune responses, including CTLs. Induction of a strong HCV-specific CTL response in HCV-infected patients can facilitate complete HCV clearance. Thus, the development of a vaccine that can induce potent CTL response against HCV is strongly expected. We investigated HCV-specific CTL responses by enzyme-linked immuno-spot assay and/or synthetic peptides and identified over 40 novel CTL epitopes in the HCV protein. Our findings may contribute to the development of the HCV vaccine. In this paper, we describe the CTL responses in HCV infection and the attempts at vaccine development based on recent scientific articles

Targeting VEGFR2 with Ramucirumab strongly impacts effector/ activated regulatory T cells and CD8+ T cells in the tumor microenvironment

Abstract Background Several studies have established a correlation between the VEGF–VEGFR2 axis and an immunosuppressive microenvironment; this immunosuppression can be overcome by anti-angiogenic reagents, such as ramucirumab (RAM). However, little is known about the immunological impact of anti-angiogenic reagents within the tumor microenvironment in human clinical samples. This study aimed at investigating the effects of RAM on the tumor microenvironmental immune status in human cancers. Methods We prospectively enrolled 20 patients with advanced gastric cancer (GC) who received RAM-containing chemotherapy. We obtained paired samples from peripheral blood mononuclear cells (PBMCs) and tumor-infiltrating lymphocytes (TILs) in primary tumors both pre- and post-RAM therapy to assess immune profiles by immunohistochemistry and flow cytometry. Results Within the tumor microenvironment, both PD-L1 expression and CD8+ T-cell infiltration increased after RAM-containing therapies. In addition, CD45RA−FOXP3highCD4+ cells (effector regulatory T cells [eTreg cells]) and PD-1 expression by CD8+ T cells were significantly reduced in TILs compared with PBMCs after RAM-containing therapies. Patients with partial response and longer progression-free survival had significantly higher pre-treatment eTreg frequencies in TILs than those with progressive disease. In in vitro analysis, VEGFR2 was highly expressed by eTreg cells. Further, VEGFA promoted VEGFR2+ eTreg cell proliferation, and this effect could be inhibited by RAM. Conclusions This study suggests that the frequency of eTreg cells in TILs could be a biomarker for stratifying clinical responses to RAM-containing therapies. Further, we propose that RAM may be employed as an immuno-modulator in combination with immune checkpoint blockade