Crosti, M. | Search bioRxiv

bioRxiv2024

Autosomal Dominant-Hyper-IgE Syndrome patients contain pre-Th17-cells that are activated by opportunistic pathogens to produce IL-10

BackgroundAutosomal Dominant-Hyper-IgE Syndrome (AD-HIES) is caused by dominant-negative (DN) STAT3 mutations and characterized by high IgE levels, a lack of Th17-cells and recurrent infections with extracellular pathogens. We previously identified an enigmatic population of IL-10 producing CCR6+B-helper T-cells and investigated here their relationship to Th17-cells and STAT3 signalling requirements. MethodsHuman blood lymphocytes were analysed by multiparametric flow cytometry in healthy donors and AD-HIES patients. Analysis was performed by conventional gating or with bioinformatic tools. FACS-purified T-cell subsets were activated in vitro and Th17 differentiation assessed. T-cell antigen specificities were assessed by activation with heat-killed pathogens or antigenic peptide pools. B helper capacities were determined according to antibody secretion in B-T co-cultures by ELISA. ResultsCCR6+Th-cells that lacked subset-defining differentiation markers were mostly non-polarised central memory T-cells (TCM) that produced IL-10 and expressed ROR{gamma}t. They were pre-committed to a Th17 fate, since TCR stimulation in the absence of polarising cytokines induced efficient Th17 differentiation. The latter was promoted by an autocrine loop of STAT3-activating cytokines. CCR6+Th-cells were reduced in patients with DN-STAT3 mutations but contained activated CCR6+TCM that produced IL-10 and responded vigorously to AD-HIES-associated pathogens. These residual CCR6+Th-cells provided B-cell help for IgG and IgE production. ConclusionsTh17 differentiation in AD-HIES patients was not completely impaired but arrested at an intermediate stage of IL-10 producing "pre-Th17"-cells. Surprisingly, DN-STAT3 mutations did not inhibit IL-10 production by CD4+T-cells. Pre-Th17-cells were activated by AD-HIES-associated pathogens and possessed B-helper functions, suggesting that they are not protective but promote aberrant IgE production.

immunology↗

bioRxiv2021

Maturation signatures of conventional dendritic cells in COVID-19 reflect direct viral sensing

Growing evidence suggests that conventional dendritic cells (cDCs) undergo aberrant maturation in COVID-19 and this negatively affects T cell activation. The presence of functional effector T cells in mild patients and dysfunctional T cells in severely ill patients suggests that adequate T cell responses are needed to limit disease severity. Therefore, understanding how cDCs cope with SARS-CoV-2 infections can help elucidate the mechanism of generation of protective immune responses. Here, we report that cDC2 subtypes exhibit similar infection-induced gene signatures with the up-regulation of interferon-stimulated genes and IL-6 signaling pathways. The main difference observed between DC2s and DC3s is the up-regulation of anti-apoptotic genes in DC3s, which explains their accumulation during infection. Furthermore, comparing cDCs between severe and mild patients, we find in the former a profound down-regulation of genes encoding molecules involved in antigen presentation, such as major histocompatibility complex class II (MHCII) molecules, {beta}2 microglobulin, TAP and costimulatory proteins, while an opposite trend is observed for proinflammatory molecules, such as complement and coagulation factors. Therefore, as the severity of the disease increases, cDC2s enhance their inflammatory properties and lose their main function, which is the antigen presentation capacity. In vitro, direct exposure of cDC2s to the virus recapitulates the type of activation observed in vivo. Our findings provide evidence that SARS-CoV-2 can interact directly with cDC2s and, by inducing the down-regulation of crucial molecules required for T cell activation, implements an efficient immune escape mechanism that correlates with disease severity.

immunology↗