Dellepiane, R. M. | bioRxiv Science

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

Follicular helper T cell signature of replicative exhaustion, apoptosis and senescence in common variable immunodeficiency

BackgroundCommon variable immunodeficiency (CVID) is the most frequent primary antibody deficiency. A significant number of CVID patients are affected by various manifestations of immune dysregulation such as autoimmunity. Follicular T cells cells are thought to support the development of CVID by providing inappropriate signals to B cells during the germinal center (GC) response. ObjectivesWe determined the possible role of follicular helper (Tfh) and follicular regulatory T (Tfr) cells in patients with CVID by phenotypic, molecular, and functional studies. MethodsWe analyzed the frequency, phenotype, transcriptome, and function of circulating Tfh cells in the peripheral blood of 27 CVID patients (11 pediatric and 16 adult) displaying autoimmunity as additional phenotype and compared them to 106 (39 pediatric and 67 adult) age-matched healthy controls. We applied Whole Exome Sequencing (WES) and Sanger sequencing to identify mutations that could account for the development of CVID and associate with Tfh alterations. ResultsA group of CVID patients (n=9) showed super-physiological frequency of Tfh1 cells and a prominent expression of PD-1 and ICOS, as well as a Tfh RNA signature consistent with highly active, but exhausted and apoptotic cells. Plasmatic CXCL13 levels were elevated in these patients and positively correlated with Tfh1 cell frequency, PD-1 levels, and an elevated frequency of CD21loCD38lo autoreactive B cells. Monoallelic variants in RTEL1, a telomere length- and DNA repair-related gene, were ideintified in four patients belonging to this group. Lymphocytes with highly shortened telomeres, and a Tfh signature enriched in genes involved in telomere elongation and response to DNA damage were seen. Histopathological analysis of the spleen in one patient showed reduced amount and size of the GC that, unexpectedly, contained an increased number of Tfh cells. ConclusionThese data point toward a novel pathogenetic mechanism in a group of patients with CVID, whereby alterations in DNA repair and telomere elongation might be involved in GC B cells, and acquisition of a Th1, highly activated but exhausted and apoptotic phenotype by Tfh cells.

immunology↗