Colony-stimulating factors and interferon-γ activate a protein related to MGF-Stat 5 to cause formation of the differentiation-induced factor in myeloid cells

International audienceThe Jak-Stat pathway of intracellular signals is used by growth factor- and cytokine receptors to induce gene transcription. We have recently reported that differentiation of myeloid cells, induced by phorbol ester, interferon-gamma (IFN-gamma) or colony-stimulating factor-1 (CSF-1) is accompanied by the activation of the differentiation-induced factor (DIF). Activated DIF specifically associates with a subclass of gamma-interferon activation site (GAS)-like DNA elements. We now report that GM-CSF, which like CSF-1 promotes the generation of mature macrophages, activates DIF. No activation was observed after treatment with the granulocyte growth and differentiation factor G-CSF. Antibodies raised against a Stat family protein, designated mammary gland factor-Stat 5 (MGF-Stat 5), reacted with DIF induced by either CSF-1, GM-CSF or IFN-gamma. Antisera to other known Stats were without effect on the DIF complex in electrophoretic mobility shift assays (EMSA). A 112 kDa protein could be isolated from either GM-CSF- or IFN-gamma-treated cells by GAS oligonucleotide precipitation. This protein reacted with antibodies to both MGF-Stat 5 and phosphotyrosine. MGF-Stat 5 and closely related proteins thus define a subfamily of Stat transcription factors that are present in a variety of cell types and are required for the onset of immediate gene expression in response to differentiating stimuli

PTPN22 R620W gene editing in T cells enhances low-avidity TCR responses

A genetic variant in the gene PTPN22 (R620W, rs2476601) is strongly associated with increased risk for multiple autoimmune diseases and linked to altered TCR regulation and T cell activation. Here, we utilize Crispr/Cas9 gene editing with donor DNA repair templates in human cord blood-derived, naive T cells to generate PTPN22 risk edited (620W), non-risk edited (620R), or knockout T cells from the same donor. PTPN22 risk edited cells exhibited increased activation marker expression following non-specific TCR engagement, findings that mimicked PTPN22 KO cells. Next, using lentiviral delivery of T1D patient-derived TCRs against the pancreatic autoantigen, islet-specific glucose-6 phosphatase catalytic subunit-related protein (IGRP), we demonstrate that loss of PTPN22 function led to enhanced signaling in T cells expressing a lower avidity self-reactive TCR, but not a high-avidity TCR. In this setting, loss of PTPN22 mediated enhanced proliferation and Th1 skewing. Importantly, expression of the risk variant in association with a lower avidity TCR also increased proliferation relative to PTPN22 non-risk T cells. Together, these findings suggest that, in primary human T cells, PTPN22 rs2476601 contributes to autoimmunity risk by permitting increased TCR signaling and activation in mildly self-reactive T cells, thereby potentially expanding the self-reactive T cell pool and skewing this population toward an inflammatory phenotype

Analysis of the impact of allergy and atopy on new onset of uveitis

PurposeThe inappropriate immune response to harmless foreign and self-antigens is a common feature of allergy, atopy and autoimmune disease. The influence of environmental factors in the initiation of autoimmunity is not well understood. It is conceivable that immune responses to allergens may also serve as a trigger of bystander immune reactions, including autoimmunity such as uveitis. Therefore, we wanted to investigate the prevalence of allergies and atopy in patients with different types of uveitis in comparison to a control cohort. MethodsIn total, 530 consecutive patients with new-onset anterior, intermediate, posterior and panuveitis were compared to a non-uveitis control cohort consisting of 1.060 consecutive new-referral patients who attended our specialized outpatient clinics for other reasons than uveitis. Allergy and atopy status as well as demographic data (age, gender and ethnicity) were obtained by standardized interviewer-assisted questionnaires. ResultsUveitis case cohort and control cohort did not differ significantly in the allergy status (p=0.910), such as the history of pollen allergy (p=0.671), history of drug allergy (p=0.920), history of food allergy (p=0.941), history of house dust mite allergy (p=0.197) or history of other allergens (p=0.593), nor in the atopy status (p=0.802), such as the history of atopic dermatitis (p=0.365), history of asthma (p=0.430) or history of allergic rhinitis (p=0.115). ConclusionsOur results argue against a substantial influence of allergies and atopy on the onset of uveitis

Germline-like TCR-α chains shared between autoreactive T cells in blood and pancreas

Abstract Human type 1 diabetes (T1D) is caused by autoimmune attack on the insulin-producing pancreatic beta cells by islet antigen-reactive T cells. How human islet antigen-reactive (IAR) CD4+ memory T cells from peripheral blood affect T1D progression in the pancreas is poorly understood. Here, we aim to determine if IAR T cells in blood could be detected in pancreas. We identify paired αβ (TRA/TRB) T cell receptors (TCRs) in IAR T cells from the blood of healthy, at-risk, new-onset, and established T1D donors, and measured sequence overlap with TCRs in pancreata from healthy, at risk and T1D organ donors. We report extensive TRA junction sharing between IAR T cells and pancreas-infiltrating T cells (PIT), with perfect-match or single-mismatch TRA junction amino acid sequences comprising ~29% total unique IAR TRA junctions (942/3,264). PIT-matched TRA junctions were largely public and enriched for TRAV41 usage, showing significant nucleotide sequence convergence, increased use of germline-encoded versus non-templated residues in epitope engagement, and a potential for cross-reactivity. Our findings thus link T cells with distinctive germline-like TRA chains in the peripheral blood with T cells in the pancreas