T Follicular Helper Cell-Dependent Clearance of a Persistent Virus Infection Requires T Cell Expression of the Histone Demethylase UTX.

Epigenetic changes, including histone methylation, control T cell differentiation and memory formation, though the enzymes that mediate these processes are not clear. We show that UTX, a histone H3 lysine 27 (H3K27) demethylase, supports T follicular helper (Tfh) cell responses that are essential for B cell antibody generation and the resolution of chronic viral infections. Mice with a T cell-specific UTX deletion had fewer Tfh cells, reduced germinal center responses, lacked virus-specific immunoglobulin G (IgG), and were unable to resolve chronic lymphocytic choriomeningitis virus infections. UTX-deficient T cells showed decreased expression of interleukin-6 receptor-α and other Tfh cell-related genes that were associated with increased H3K27 methylation. Additionally, Turner Syndrome subjects, who are predisposed to chronic ear infections, had reduced UTX expression in immune cells and decreased circulating CD4(+) CXCR5(+) T cell frequency. Thus, we identify a critical link between UTX in T cells and immunity to infection.

Myeloid-derived suppressor cells are increased in frequency but not maximally suppressive in peripheral blood of Type 1 Diabetes Mellitus patients.

Type 1 Diabetes Mellitus (T1D) results from the destruction of insulin-producing beta cells in the pancreas by autoreactive T cells. Myeloid derived suppressor cells (MDSCs) are a recently identified immune cell subset that down-regulate T cells. Whether defects in MDSC numbers or function may contribute to T1D pathogenesis is not known. We report here that MDSCs are unexpectedly enriched in peripheral blood of both mice and patients with autoimmune diabetes. Peripheral blood MDSCs from T1D patients suppressed T cell proliferation in a contact-dependent manner; however, suppressive function could be enhanced with in vitro cytokine induction. These findings suggest that native T1D MDSCs are not maximally suppressive and that strategies to promote MDSC suppressive function may be effective in preventing or treating T1D.

HLA-A2-matched peripheral blood mononuclear cells from type 1 diabetic patients, but not nondiabetic donors, transfer insulitis to NOD-scid/γc(null)/HLA-A2 transgenic mice concurrent with the expansion of islet-specific CD8+ T cells.

OBJECTIVE: Type 1 diabetes is an autoimmune disease characterized by the destruction of insulin-producing ß-cells. NOD mice provide a useful tool for understanding disease pathogenesis and progression. Although much has been learned from studies with NOD mice, increased understanding of human type 1 diabetes can be gained by evaluating the pathogenic potential of human diabetogenic effector cells in vivo. Therefore, our objective in this study was to develop a small-animal model using human effector cells to study type 1 diabetes. RESEARCH DESIGN AND METHODS: We adoptively transferred HLA-A2-matched peripheral blood mononuclear cells (PBMCs) from type 1 diabetic patients and nondiabetic control subjects into transgenic NOD-scid/γc(null)/HLA-A*0201 (NOD-scid/γc(null)/A2) mice. At various times after adoptive transfer, we determined the ability of these mice to support the survival and proliferation of the human lymphoid cells. Human lymphocytes were isolated and assessed from the blood, spleen, pancreatic lymph node and islets of NOD-scid/γc(null)/A2 mice after transfer. RESULTS: Human T and B cells proliferate and survive for at least 6 weeks and were recovered from the blood, spleen, draining pancreatic lymph node, and most importantly, islets of NOD-scid/γc(null)/A2 mice. Lymphocytes from type 1 diabetic patients preferentially infiltrate the islets of NOD-scid/γc(null)/A2 mice. In contrast, PBMCs from nondiabetic HLA-A2-matched donors showed significantly less islet infiltration. Moreover, in mice that received PBMCs from type 1 diabetic patients, we identified epitope-specific CD8(+) T cells among the islet infiltrates. CONCLUSIONS: We show that insulitis is transferred to NOD-scid/γc(null)/A2 mice that received HLA-A2-matched PBMCs from type 1 diabetic patients. In addition, many of the infiltrating CD8(+) T cells are epitope-specific and produce interferon-γ after in vitro peptide stimulation. This indicates that NOD-scid/γc(null)/A2 mice transferred with HLA-A2-matched PBMCs from type 1 diabetic patients may serve as a useful tool for studying epitope-specific T-cell-mediated responses in patients with type 1 diabetes.