Biology subjects

Lacorcia, M.

Publications and source records attributed to Lacorcia, M..

3 recordsLinked to original sources

bioRxiv2025

BASTA, a simple whole blood assay for measuring beta-cell antigen specific CD4+ T-cell responses in type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease where T-cells mediate the destruction of the insulin-producing {beta}-cells found within the Islets of Langerhans in the pancreas. Currently, autoantibodies to {beta}-cell antigens are the only tests available to detect {beta}-cell autoimmunity. T-cell responses to {beta}-cell antigens, which are known to cause T1D, can only be measured in research settings due to the complexity of assays and the large blood volumes required. Here we describe the {beta}-cell antigen specific T-cell assay - BASTA. BASTA is a simple whole blood assay that can detect human CD4+ T-cell responses to {beta}-cell antigens by measuring antigen-stimulated IL-2 production. BASTA is both more sensitive and specific than the CFSE-based Proliferation Assay. We used BASTA to identify the regions of preproinsulin which stimulated T-cell responses specifically in blood from people with T1D. BASTA can be done with as little as 2-3 mL of blood. We found that effector memory CD4+ T cells are the primary producers of IL-2 in response to preproinsulin peptides. We then evaluated responses to individual and pooled preproinsulin peptides in a cross-sectional study of pediatric subjects: without T1D, without T1D but with a first-degree relative with T1D, or diagnosed with T1D. In contrast to other preproinsulin peptides, full-length C-peptide (PI33-63) showed excellent specificity for T1D (AUC = 0.86). We suggest that BASTA will be a useful tool for monitoring changes in {beta}-cell specific CD4+ T-cell responses both in research and clinical settings. One Sentence Summary{beta}-cell antigen specific CD4+ T-cell responses in children with T1D can be measured using a simple whole blood assay.

immunology↗

bioRxiv2024

Proinsulin C-peptide is a major source of HLA-DQ8 restricted HIPs recognized by human Islet-Infiltrating CD4+ T cells

Type 1 diabetes (T1D) is an autoimmune disease that develops when T cells destroy the pancreatic insulin-producing beta cells that reside in the pancreatic islets. Immune cells, including T cells infiltrate the islets and gradually destroy the beta cells. Human islet-infiltrating CD4+ T cells recognize peptide epitopes derived from proinsulin, particularly C-peptide. Hybrid Insulin peptides (HIPs) are neoepitopes formed by the fusion of two peptides derived from beta-cell granule proteins and are known to be the targets of pathogenic CD4+ T cells in the NOD mouse and human islet-infiltrating CD4+ T cells. Proinsulin is widely recognized as a central antigen in T1D, but its role in forming HIPs is unclear. We developed a method to functionally screen TCRs derived from human islet-infiltrating CD4+ T cells and applied this to the identification of new proinsulin-derived HIPs. We generated a library of 4,488 candidate HIPs formed by fusion of proinsulin fragments and predicted to bind to HLA-DQ8. This library was screened against 109 islet-infiltrating CD4+ T-cell TCRs isolated from four organ donors who had T1D. We identified 13 unique HIPs recognized by 9 different TCRs from two organ donors. HIP specific T-cell avatars responded specifically to a peptide extract from human islets. These new HIPs predominantly stimulated CD4+ T-cell proliferation in PBMCs from people with T1D in contrast to HLA-matched controls. This is the first unbiased functional, islet-infiltrating T-cell based, screen to identify proinsulin derived HIPs. It has revealed many new HIPs and a central role of proinsulin C-peptide in their formation. SUMMARYType 1 diabetes is an autoimmune disease caused by T cells destroying the pancreatic insulin-producing beta cells. The antigens/epitopes seen by disease promoting CD4+ T cells are poorly understood. Hybrid insulin peptides (HIPs) are a new class of CD4+ antigen recognized by pathogenic NOD mouse CD4+ T cells. In humans very few HIPs recognized by human islet-infiltrating CD4+ T cells are known. We show that proinsulin HIPs are recognized by human islet-infiltrating CD4+ T cells from T1D donors and describe 13 new HIPs formed by fusion of proinsulin peptides. This work shows that proinsulin, particularly C-peptide, is a major contributor to the pool HIPs recognized by human islet-infiltrating CD4+ T cells and are therefore central to autoimmunity in T1D.

immunology↗

bioRxiv2021

IL-4 and helminth infection downregulate MINCLE-dependent macrophage response to mycobacteria and Th17 adjuvanticity

The myeloid C-type lectin receptor (CLR) MINCLE senses the mycobacterial cell wall component trehalose-6,6-dimycolate (TDM). Recently, we found that IL-4 down-regulates MINCLE expression in macrophages. IL-4 is a hallmark cytokine in helminth infections, which appear to increase the risk for mycobacterial infection and active tuberculosis. Here, we investigated functional consequences of IL-4 and helminth infection on MINCLE-driven macrophage activation and Th1/Th17 adjuvanticity. IL-4 inhibited MINCLE and cytokine induction after macrophage infection with Mycobacterium bovis Bacille Calmette-Guerin (BCG). Infection of mice with BCG upregulated MINCLE on myeloid cells, which was inhibited by IL-4 plasmid injection and by infection with the nematode Nippostrongylus brasiliensis in monocytes. To determine the impact of helminth infection on MINCLE-dependent immune responses, we vaccinated mice with a recombinant protein together with the MINCLE ligand Trehalose-6,6-dibehenate (TDB) as adjuvant. Concurrent infection with N. brasiliensis or with Schistosoma mansoni promoted T cell-derived IL-4 production and suppressed Th1/Th17 differentiation in the spleen. In contrast, helminth infection did not reduce Th1/Th17 induction by TDB in draining peripheral lymph nodes, where IL-4 levels were unaltered. Upon use of the TLR4-dependent adjuvant G3D6A, N. brasiliensis infection impaired selectively the induction of splenic antigen-specific Th1 but not of Th17 cells. Thus, helminth infection attenuated the Th17 response to MINCLE-dependent immunization in an organ-specific manner. Taken together, our results demonstrate down-regulation of MINCLE expression on monocytes and macrophages by IL-4 as a possible mechanism of thwarted Th17 vaccination responses by underlying helminth infection.

immunology↗