Project description:Cell Atlas of COVID-19 patients with Pre-existing Autoimmunity and Immunodeficiency conditions
COVID-19 disease is characterized by hyperinflammation of the lungs and poor immune response against the virus, leading to acute respiratory distress syndrome. Patients with pre-existing medical conditions strongly correlated with poorer clinical outcomes upon SARS-CoV-2 infection. This study aims to characterize the cellular response to SARS-CoV-2 infection in controls and in patients with primary immunodeficiency and autoimmune disease.
This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/
Project description:Purine nucleoside phosphorylase (PNP) enables the breakdown and recycling of guanine nucleosides. PNP insufficiency in humans is paradoxically associated with both immunodeficiency and autoimmunity, but the mechanistic basis for these outcomes is incompletely understood. Here we identify two immune lineage-dependent consequences of PNP inactivation dictated by distinct gene interactions. During T cell development, PNP inactivation is synthetically lethal with down-regulation of the dNTP triphosphohydrolase SAMHD1. This interaction requires deoxycytidine kinase activity and is antagonized by microenvironmental deoxycytidine. In B lymphocytes and macrophages, PNP regulates Toll like receptor 7 signaling by controlling the levels of its (deoxy)guanosine nucleoside ligands. Overriding this regulatory mechanism promotes germinal center formation in the absence of exogenous antigen and accelerates disease in a mouse model of autoimmunity. This work reveals that one purine metabolism gene protects against immunodeficiency and autoimmunity via independent mechanisms operating in distinct immune lineages and identifies PNP as a novel metabolic immune checkpoint.
Project description:The transcription factor FOXN1 acts in a gene-dosage sensitive way as a master regulator of thymic epithelial cell development and maintenance enabling effective thymopoiesis. Its autosomal recessive loss of function is the molecular cause of the “nude” phenotype, a severe combined immunodeficiency caused by athymia. Here we report on a spontaneously occurring, novel heterozygous FOXN1 mutation that initially permits regular thymus organogenesis but results in a failure of thymic maintenance beyond late stages of human gestation. Modeling the mutation in mice results in divergent disruptions of normal TEC subtype differentiation and function. Transcriptionally inactive, the mutant disrupts the formation of wild type FOXN1 homo-multimers and occupies canonical DNA binding sites, at which it operates in a dominant negative fashion to displace wild type FOXN1 from nuclear condensates. Comparing the interactome of the mutant and wild type FOXN1 identified binding partners that uniquely interact with wild type FOXN1 and are characteristic constituents of nuclear organelles required for transcription. Mutant FOXN1 moves in and out of condensates over a time-course indistinguishable from that of wild type FOXN1, suggesting that the mutation did not affect the molecular movement of FOXN1. Thus, we have identified a clinically relevant gain of function mutation of FOXN1 that actively prevents the transcriptional activity of wild type FOXN1 and provides critical insight into the mechanism by which FOXN1 operates in controlling sustained gene expression necessary for normal thymic epithelial cell differentiation, maintenance and function.
Project description:This study reports two unrelated patients with a combined immunodeficiency. Whole-exome sequencing of both patients, their healthy parents and siblings identified in both families a /de novo/ missense variant in /ITPR3/ (NM_002224.3:c.7570C>T, p.Arg2524Cys). While the mRNA level in patients remained the same as in healthy siblings and controls, the level of protein expression was diminished. It was also shown that the ITPR3 heterozygous p.Arg2524Cys mutation impairs calcium flux function in dermal fibroblast of one patient and in a knock-in Jurkat T cell line.
Project description:This study reports two unrelated patients with a combined immunodeficiency. Whole-exome sequencing of both patients, their healthy parents and siblings identified a single de novo missense variant in ITPR3 (NM_002224.3:c.7570C>T, p.Arg2524Cys) in both index cases. While the mRNA level in patients remained the same as in healthy siblings and controls, the level of protein expression was diminished. It was also shown that the ITPR3 heterozygous p.Arg2524Cys mutation impairs calcium flux function in dermal fibroblast of one patient and in a knock-in Jurkat T cell line. Two additional patients with related phenotypes and the same mutation were further identified and described in the study. The present dataset corresponds to the RNAseq performed on PBMC of patient 2 of the study and healthy controls.
Project description:Intracellular calcium levels are finely tuned through intricate actions of a number of channels and transporters, including those at key endocellular stores, e.g. endoplasmic reticulum (ER), lysosomes, and mitochondria. Along with the highly homologous genes Inositol 1,4,5-trisphosphate (IP3) receptor type 1 (ITPR1) and 2 (ITPR2), ITPR3 encodes the IP3 receptor (IP3R), a key player in intracellular calcium release in animals. Here we report the first cases of ITPR3 defects in man leading to a primarily dysimmune phenotype. In four unrelated patients of diverse ethnicity, and suffering from a complex immunodeficiency syndrome, we report the same de novo pathogenic variant - c.7570C>T; p.Arg2524Cys - in ITPR3. Clinically, recurrent severe infectious episodes of viral and bacterial origins, features of ectodermal dysplasia and that of Charcot-Marie-Tooth disease were paramount. The identified variant does not affect gene transcription, yet it was structurally predicted and biologically proven to disrupt proper protein folding and function in vivo. This eventually leads to defective Calcium flux in patient cells, dysregulation of mitochondrial function and a broad dysimmune phenotype characterized primarily by a profound CD4 T cell lymphopenia associated with quasi absence of naïve CD4 and CD8 cells, itself mirrored by an increase in cognate memory cells. The Calcium signaling defect was recapitulated ex vivo through the introduction of this single variant in Jurkat cells. Moreover, site-directed mutagenesis displayed the exquisite sensitivity of Arg2524 to any amino acid change. In conclusion, a single unique recurrent de novo variant in ITPR3 leads to a novel syndromic immunodeficiency.