Project description:Newborn screening for severe combined immunodeficiency (SCID) has not only accelerated diagnosis and improved treatment for affected infants, but also led to identification of novel genes required for human T cell development. A male proband had SCID newborn screening showing very low T cell receptor excision circles (TRECs), a biomarker for thymic output of nascent T cells. He had persistent profound T lymphopenia, but normal numbers of B and natural killer (NK) cells. Despite an allogeneic hematopoietic stem cell transplant from his brother, he failed to develop normal T cells. Targeted resequencing excluded known SCID genes; however, whole exome sequencing (WES) of the proband and parents revealed a maternally inherited X-linked missense mutation in MED14 (MED14V763A), a component of the mediator complex. Morpholino (MO)-mediated loss of MED14 function attenuated T cell development in zebrafish. Moreover, this arrest was rescued by ectopic expression of cDNA encoding the wild type human MED14 ortholog, but not by MED14V763A , suggesting that the variant impaired MED14 function. Modeling of the equivalent mutation in mouse (Med14V769A) did not disrupt T cell development at baseline. However, repopulation of peripheral T cells upon competitive bone marrow transplantation was compromised, consistent with the incomplete T cell reconstitution experienced by the proband upon transplantation with bone marrow from his healthy male sibling, who was found to have the same MED14V763A variant. Suspecting that the variable phenotypic expression between the siblings was influenced by further mutation(s), we sought to identify genetic variants present only in the affected proband. Indeed, WES revealed a mutation in the L1 cell adhesion molecule (L1CAMQ498H); however, introducing that mutation in vivo in mice did not disrupt T cell development. Consequently, immunodeficiency in the proband may depend upon additional, unidentified gene variants.
Project description:While monogenic variants in CDC45-MCM-GINS (CMG) replisome proteins cause human natural killer cell deficiencies (NKD), family members with the same inherited variants often have variable clinical and cellular phenotypes. Using iPSCs from two siblings with the same hereditary compound heterozygous GINS4 variants but variable disease expressivity, we modeled cell proliferation dynamics and the effect of GINS4 variants on NK cell development from pluripotent stem cells. Cell cycle impairment and increased apoptosis were detected in NK cells from patient-derived iPSCs following NK cell lineage commitment but not in pluripotent cells. While this effect was detected in cell lines from both siblings, the efficiency of NK cell differentiation was variable and correlated with differential clinical severity of NKD. Further investigation of allelic expression of inherited GINS4 variants demonstrated equal biallelic expression of GINS4 in pluripotent cells and primary CD34+ progenitors. However, allelic bias in lineage committed NK cells led to over- or under-representation of more damaging inherited GINS4 heterozygous variants that tracked with differential cellular and clinical severity. This study identifies allelic bias as an epigenetic factor that contributes to the phenotypic variations of monogenic diseases and further defines the etiology of NK cell-lineage specific immunodeficiency arising from CMG variants.
Project description:While monogenic variants in CDC45-MCM-GINS (CMG) replisome proteins cause human natural killer cell deficiencies (NKD), family members with the same inherited variants often have variable clinical and cellular phenotypes. Using iPSCs from two siblings with the same hereditary compound heterozygous GINS4 variants but variable disease expressivity, we modeled cell proliferation dynamics and the effect of GINS4 variants on NK cell development from pluripotent stem cells. Cell cycle impairment and increased apoptosis were detected in NK cells from patient-derived iPSCs following NK cell lineage commitment but not in pluripotent cells. While this effect was detected in cell lines from both siblings, the efficiency of NK cell differentiation was variable and correlated with differential clinical severity of NKD. Further investigation of allelic expression of inherited GINS4 variants demonstrated equal biallelic expression of GINS4 in pluripotent cells and primary CD34+ progenitors. However, allelic bias in lineage committed NK cells led to over- or under-representation of more damaging inherited GINS4 heterozygous variants that tracked with differential cellular and clinical severity. This study identifies allelic bias as an epigenetic factor that contributes to the phenotypic variations of monogenic diseases and further defines the etiology of NK cell-lineage specific immunodeficiency arising from CMG variants.
Project description:Inborn errors of immunity (IEI) result in increased morbidity and mortality from infections. However, discovering new IEIs is limited by the clinical identification of rare patient cohorts. To predict immunodeficiency-associated genes in a patient-independent approach, we performed a targeted CRISPR-Cas9 knockout screen in healthy human donor-derived PBMCs and identified myocyte enhancer factor 2C (MEF2C) as essential for primary human natural killer (NK) cell functionality ex vivo. MEF2C haploinsufficient (MCHS) patients and mice displayed impaired NK cell development, ex vivo function, and increased susceptibility to viral infection. MEF2C was required for cytokine-induced changes in NK cell metabolism and SREBP-mediated lipid homeostasis, and oleic acid supplementation restored MCHS patient NK cell cytotoxic function. Thus, we demonstrate a CRISPR-based methodology in primary human immune cells to accelerate the identification of new IEIs, and apply this approach to predict and validate a new NK cell immunodeficiency associated with metabolic and functional defects.
Project description:A substantial proportion of common variable immunodeficiency (CVID) patients has duodenal inflammation of largely unknown etiology. However, because of its histologic similarities with celiac disease, gluten sensitivity has been proposed as a potential mechanism. We aimed to elucidate the role of the duodenal microenvironment in the pathogenesis of duodenal inflammation in CVID by investigating the transcriptional, proteomic, and microbial signatures of duodenal biopsy samples in CVID.
Project description:More insights into the character differences between ChAT+ and ChAT- NK cells were obtained based on the gene-expression patterns. A clear delineation between ChAT+ NK cells and ChAT- NK cells was observed, with a total of 300 genes over-expressed and 941 genes under-expressed significantly in the ChAT+ subset. It will provide evidences for further investigation into their functional characters
Project description:Investigation of the change of the Trail-dependent NK cell transcriptome during short-term (24h) infection with lymphocytic choriomeningitis virus (LCMV). RNA sequencing-based transcriptomics analysis was performed in spleen-isolated (NK1.1+CD3-) NK cells from 3 naïve Trail+/+ mice, 3 naive Trail-/- mice, 4 LCMV-infected Trail+/+ mice, and 4 LCMV-infected Trail-/- mice.