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: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: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:Mutations in the DOCK8 gene cause an autosomal recessive form of hyper-immunoglobulin E syndrome, characterised by chronic immunodeficiency with persistent microbial infection and increased incidence of malignancy. These manifestations suggest a defect in cytotoxic lymphocyte function and immune surveillance. However, how DOCK8 regulates NK cell-driven immune responses remains unclear. Here, we demonstrate that DOCK8 regulates NK cell cytotoxicity and cytokine production in response to target cell engagement or receptor ligation. Genetic ablation of DOCK8 in human NK cells attenuated cytokine transcription and secretion through inhibition of Src family kinase activation, particularly Lck, downstream of target cell engagement or NKp30 ligation. PMA/Ionomycin treatment of DOCK8 deficient NK cells rescued cytokine production, indicating a defect proximal to receptor ligation. Importantly, NK cells from DOCK8 deficient patients had attenuated production of IFNγ and TNFα upon NKp30 stimulation. Taken together, we reveal a novel molecular mechanism by which DOCK8 regulates NK cell driven immunity.
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.
Project description:NK cells are lymphocytes that provide a first defense against viral infections and cancer. They act (i) cytotoxic by killing virus-infected and tumorigenic cells and (ii) immune regulatory by releasing cytokines and chemokines. These innate immune cells are commonly further classified as CD56bright and CD56dim NK cells. Former studies confirmed immune regulatory CD56bright NK cells as progenitors of cytotoxic CD56dim NK cells. CD57 was previously described as T cell marker for senescence and terminal differentiation. Recent studies detected CD57+ and CD57- NK cells among the CD56dim NK cell population and suggested a fully mature developmental status for CD57+ NK cells. The recent NK cell maturation model includes CD34+ hematopoietic stem cells (HSC), which develop into CD56bright NK cells, later into CD56dimCD57- and finally into terminally maturated CD56dimCD57+ (1) (2) (3). The molecular mechanisms of human NK cell differentiation and maturation remain unknown to this date. We performed for the first time a proteomic analysis of these distinct developmental stages of human primary NK cells, isolated from overall 10 healthy human blood donors. CD56bright NK cells versusCD56dim and CD56dimCD57- versus CD56dimCD57+ NK cells were analyzed by using quantitative peptide sequencing, which revealed individual protein signatures (3400 proteins) of these different NK cell developmental stages. Notably, our data support the current NK cell differentiation model by highlighting both strong distinctions between CD56dim/bright NK cells and close relationships between CD57+/- NK cells on the proteomic level. Among the most prominent and conserved regulated proteins, we detected myosin IIa, Calvasculin and Calcyclin with very similar expression patterns. We investigated their sub-cellular localization and observed specific recruitment- and accumulation-events at the NK cell immunological synapse (NKIS) after NK activation.
Project description:Somatic STAT5B gain-of-function mutations have been frequently found in patients with T- and NK-cell neoplasms. STAT5BN642H represents the most frequently occuring STAT5B mutation. To investigate the molecular mechanism of STAT5BN642H-driven NK-cell leukemia, we performed RNA-Seq of liver derived FACS-sorted diseased N642HNK/NK and aged non-diseased control (Cre neg, GFPNK/NK), STAT5BNK/NK, N642HNK/NK NK cells.