The TNF Receptor Superfamily in Co-stimulating and Co-inhibitory Responses.

Cytokines related to tumor necrosis factor (TNF) provide a communication network essential for coordinating multiple cell types into an effective host defense system against pathogens and malignant cells. The pathways controlled by the TNF superfamily differentiate both innate and adaptive immune cells and modulate stromal cells into microenvironments conducive to host defenses. Members of the TNF receptor superfamily activate diverse cellular functions from the production of type 1 interferons to the modulation of survival of antigen-activated T cells. Here, we focus attention on the subset of TNF superfamily receptors encoded in the immune response locus in chromosomal region 1p36. Recent studies have revealed that these receptors use diverse mechanisms to either co-stimulate or restrict immune responses. Translation of the fundamental mechanisms of TNF superfamily is leading to the design of therapeutics that can alter pathogenic processes in several autoimmune diseases or promote immunity to tumors.

Combined sublethal irradiation and agonist anti-CD40 enhance donor T cell accumulation and control of autochthonous murine pancreatic tumors.

Tumor-reactive T lymphocytes can promote the regression of established tumors. However, their efficacy is often limited by immunosuppressive mechanisms that block T cell accumulation or function. ACT provides the opportunity to ameliorate immune suppression prior to transfer of tumor-reactive T cells to improve the therapeutic benefit. We evaluated the combination of lymphodepleting whole body irradiation (WBI) and agonist anti-CD40 (αCD40) antibody on control of established autochthonous murine neuroendocrine pancreatic tumors following the transfer of naïve tumor-specific CD8 T cells. Sublethal WBI had little impact on disease outcome but did promote T cell persistence in the lymphoid organs. Host conditioning with αCD40, an approach known to enhance APC function and T cell expansion, transiently increased donor T cell accumulation in the lymphoid organs and pancreas, but failed to control tumor progression. In contrast, combined WBI and αCD40 prolonged T cell proliferation and dramatically enhanced accumulation of donor T cells in both the lymphoid organs and pancreas. This dual conditioning approach also promoted high levels of inflammation in the pancreas and tumor, induced histological regression of established tumors, and extended the lifespan of treated mice. Prolonged survival was entirely dependent upon adoptive transfer, but only partially dependent upon IFNγ production by donor T cells. Our results identify the novel combination of two clinically relevant host conditioning approaches that synergize to overcome immune suppression and drive strong tumor-specific T cell accumulation within well-established tumors.

Epitope topography of agonist antibodies to the checkpoint inhibitory receptor BTLA.

B and T lymphocyte attenuator (BTLA) is an attractive target for a new class of therapeutics that attempt to rebalance the immune system by agonizing checkpoint inhibitory receptors (CIRs). Herpesvirus entry mediator (HVEM) binds BTLA in both trans- and cis-orientations. We report here the development and structural characterization of three humanized BTLA agonist antibodies, 22B3, 25F7, and 23C8. We determined the crystal structures of the antibody-BTLA complexes, showing that these antibodies bind distinct and non-overlapping epitopes of BTLA. While all three antibodies activate BTLA, 22B3 mimics HVEM binding to BTLA and shows the strongest agonistic activity in functional cell assays and in an imiquimod-induced mouse model of psoriasis. 22B3 is also capable of modulating HVEM signaling through the BTLA-HVEM cis-interaction. The data obtained from crystal structures, biochemical assays, and functional studies provide a mechanistic model of HVEM and BTLA organization on the cell surface and informed the discovery of a highly active BTLA agonist.

Impairment of Bone Remodeling in LIGHT/TNFSF14-Deficient Mice.

Multiple cytokines produced by immune cells induce remodeling and aid in maintaining bone homeostasis through differentiation of bone-forming osteoblasts and bone-resorbing osteoclasts. Here, we investigate bone remodeling controlled by the tumor necrosis factor (TNF) superfamily cytokine LIGHT. LIGHT-deficient mice (Tnfsf14-/- ) exhibit spine deformity and reduced femoral cancellous bone mass associated with an increase in the osteoclast number and a slight decrease of osteoblasts compared with WT mice. The effect of LIGHT in bone cells can be direct or indirect, mediated by both the low expression of the anti-osteoclastogenic osteoprotegerin (OPG) in B and T cells and reduced levels of the pro-osteoblastogenic Wnt10b in CD8+ T cells in Tnfsf14-/- mice. LIGHT stimulation increases OPG levels in B, CD8+ T, and osteoblastic cells, as well as Wnt10b expression in CD8+ T cells. The high bone mass in Light and T- and B-cell-deficient mice (Rag- /Tnfsf14- ) supports the cooperative role of the immune system in bone homeostasis. These results implicate LIGHT as a potential target in bone disease. © 2017 American Society for Bone and Mineral Research.

Whole-body irradiation increases the magnitude and persistence of adoptively transferred T cells associated with tumor regression in a mouse model of prostate cancer.

Adoptive immunotherapy has demonstrated efficacy in a subset of clinical and preclinical studies, but the T cells used for therapy often are rendered rapidly nonfunctional in tumor-bearing hosts. Recent evidence indicates that prostate cancer can be susceptible to immunotherapy, but most studies using autochthonous tumor models demonstrate only short-lived T-cell responses in the tolerogenic prostate microenvironment. Here, we assessed the efficacy of sublethal whole-body irradiation (WBI) to enhance the magnitude and duration of adoptively transferred CD8(+) T cells in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model. We demonstrate that WBI promoted high-level accumulation of granzyme B (GzB, Gzmb)-expressing donor T cells both in lymphoid organs and in the prostate of TRAMP mice. Donor T cells remained responsive to vaccination in irradiated recipients, but a single round of WBI-enhanced adoptive immunotherapy failed to affect significantly the existing disease. Addition of a second round of immunotherapy promoted regression of established disease in half of the treated mice, with no progression observed. Regression was associated with long-term persistence of effector/memory phenotype CD8(+) donor cells. Administration of the second round of adoptive immunotherapy led to reacquisition of GzB expression by persistent T cells from the first transfer. These results indicate that WBI conditioning amplifies tumor-specific T cells in the TRAMP prostate and lymphoid tissue, and suggest that the initial treatment alters the tolerogenic microenvironment to increase antitumor activity by a second wave of donor cells.

Anaplastic renal carcinoma expressing SV40 T antigen in a female TRAMP mouse.

An 8-mo-old female transgenic adenocarcinoma of the mouse prostate (C57BL/6-Tg(TRAMP)8247Ng/J) mouse presented with abdominal distention, lethargy, and serosanguineous vaginal discharge. A large primary renal tumor with metastases to lung and liver was present at necropsy. The tumor was composed of poorly differentiated and crowded epithelial cells forming ducts, acini, and cribriform patterns, with comedonecrosis and frequent bizarre mitoses. Immunohistochemistry revealed that neoplastic cells expressed nuclear SV40 T antigen, confirming aberrant expression of the transgene. In addition, cells were positive for pancytokeratin and negative for synaptophysin and estrogen and progesterone receptors. This report details the first transgene-induced tumor in a female TRAMP mouse.