RESUMO
Few monogenic causes for severe manifestations of common allergic diseases have been identified. Through next-generation sequencing on a cohort of patients with severe atopic dermatitis with and without comorbid infections, we found eight individuals, from four families, with novel heterozygous mutations in CARD11, which encodes a scaffolding protein involved in lymphocyte receptor signaling. Disease improved over time in most patients. Transfection of mutant CARD11 expression constructs into T cell lines demonstrated both loss-of-function and dominant-interfering activity upon antigen receptor-induced activation of nuclear factor-κB and mammalian target of rapamycin complex 1 (mTORC1). Patient T cells had similar defects, as well as low production of the cytokine interferon-γ (IFN-γ). The mTORC1 and IFN-γ production defects were partially rescued by supplementation with glutamine, which requires CARD11 for import into T cells. Our findings indicate that a single hypomorphic mutation in CARD11 can cause potentially correctable cellular defects that lead to atopic dermatitis.
Assuntos
Proteínas Adaptadoras de Sinalização CARD/genética , Dermatite Atópica/genética , Mutação em Linhagem Germinativa , Guanilato Ciclase/genética , Sistema ASC de Transporte de Aminoácidos/metabolismo , Estudos de Coortes , Análise Mutacional de DNA , Dermatite Atópica/imunologia , Feminino , Genes Dominantes , Glutamina/metabolismo , Humanos , Células Jurkat , Ativação Linfocitária , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina , Antígenos de Histocompatibilidade Menor/metabolismo , Complexos Multiproteicos/metabolismo , NF-kappa B/metabolismo , Linhagem , Linfócitos T/imunologia , Linfócitos T/metabolismo , Serina-Treonina Quinases TOR/metabolismoRESUMO
Most polyreactive and antinuclear antibodies are removed from the human antibody repertoire during B cell development. To elucidate how B cell receptor (BCR) signaling may regulate human B cell tolerance, we tested the specificity of recombinant antibodies from single peripheral B cells isolated from patients suffering from X-linked agammaglobulinemia (XLA). These patients carry mutations in the Bruton's tyrosine kinase (BTK) gene that encode an essential BCR signaling component. We find that in the absence of Btk, peripheral B cells show a distinct antibody repertoire consistent with extensive secondary V(D)J recombination. Nevertheless, XLA B cells are enriched in autoreactive clones. Our results demonstrate that Btk is essential in regulating thresholds for human B cell tolerance.