Gain‐of‐function STAT1 mutations impair STAT3 activity in patients with chronic mucocutaneous candidiasis (CMC)

Abstract

Signal transducer and activator of transcription 3 (STAT3) triggered production of Th-17 cytokines mediates protective immunity against fungi. Mutations affecting the STAT3/interleukin 17 (IL-17) pathway cause selective susceptibility to fungal (Candida) infections, a hallmark of chronic mucocutaneous candidiasis (CMC). In patients with autosomal dominant CMC, we and others previously reported defective Th17 responses and underlying gain-of-function (GOF) STAT1 mutations, but how this affects STAT3 function leading to decreased IL-17 is unclear. We also assessed how GOF-STAT1 mutations affect STAT3 activation, DNA binding, gene expression, cytokine production, and epigenetic modifications. We excluded impaired STAT3 phosphorylation, nuclear translocation, and sequestration of STAT3 into STAT1/STAT3 heterodimers and confirm significantly reduced transcription of STAT3-inducible genes (RORC/IL-17/IL-22/IL-10/c-Fos/SOCS3/cMyc) as likely underlying mechanism. STAT binding to the high affinity sis-inducible element was intact but binding to an endogenous STAT3 DNA target was impaired. Reduced STAT3-dependent gene transcription was reversed by inhibiting STAT1 activation with fludarabine or enhancing histone, but not STAT1 or STAT3 acetylation with histone deacetylase (HDAC) inhibitors trichostatin A or ITF2357. Silencing HDAC1, HDAC2, and HDAC3 indicated a role for HDAC1 and 2. Reduced STAT3-dependent gene transcription underlies low Th-17 responses in GOF-STAT1 CMC, which can be reversed by inhibiting acetylation, offering novel targets for future therapies.Correspondence: Dr. Desa Lilic e-mail: desa.lilic@ncl.ac.uk * Both authors contributed equally to this work.C 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.eji-journal.eu Eur. J. Immunol. 2015. 45: 2834-2846 Immunity to infection 2835 Keywords: Chronic mucocutaneous candidiasis (CMC) HDAC inhibitors IL-17 STAT1 gain-of-function mutation STAT3 STAT1 inhibitorsAdditional supporting information may be found in the online version of this article at the publisher's web-site IntroductionPatients with chronic mucocutaneous candidiasis (CMC) present with recurrent or persistent infections of the skin, nails, and mucosal membranes with the fungus Candida [1]. Candida is an opportunistic yeast that does not cause disease in healthy individuals despite inhabiting bodily surfaces as it is controlled by immune mechanisms, specifically Th-17 cells and cytokines produced by them [2]. Mucosal infections with Candida species indicate an underlying T-cell deficiency, which is most often secondary to immunosuppressive and/or chemotherapy, antibiotics, biological therapies, HIV, or other permissive circumstances. However, in rare patients, these infections present as a severe syndrome coined CMC, a primary immune deficiency in which the underlying cause is a genetic mutation affecting immune pathways essential for fungal protection [3]. Research in primary immune deficiency patients with isolated CMC has documented the crucial role of the signal transducer and activator of tra...

A Novel Heterozygous Mutation in the STAT1 SH2 Domain Causes Chronic Mucocutaneous Candidiasis, Atypically Diverse Infections, Autoimmunity, and Impaired Cytokine Regulation

“…After stimulation with cytokines, STAT1 phosphorylation in the T lymphocytes of both patients reached higher levels compared to the healthy controls. In contrast to previous reports studying mutations in other STAT1 domains (11–13), we found no clear prolonged STAT1 phosphorylation in the T lymphocytes from the patients. The difference in the mutated domain of STAT1 could possibly be the cause of different phosphorylation characteristics.…”

Partial growth hormone insensitivity and dysregulatory immune disease associated with de novo germline activating STAT3 mutations

“…These findings suggest that enhanced activity of STAT3 variants in response to GH decrease STAT5b function by slightly different mechanisms, leading to partial GH insensitivity. Further studies are necessary to elucidate the underlying mechanisms, that can include the formation of nonfunctional STAT5b/STAT3 heterodimers, competition for common receptor docking sites and regulation for posttranslational epigenetic modifications, as was recently described for GOF-STAT1 mutations and their effects on STAT3 function (Zheng et al, 2015). …”

Genetic, immunological, and clinical features of patients with bacterial and fungal infections due to inherited IL-17RA deficiency

“…Finally, AD signal transducer and activator of transcription 1 (STAT1) gain of function (GOF) was reported in ∼350 patients with syndromic CMCD and found in approximately half of such patients in our study cohort. In patients with STAT1 GOF mutations, CMC results, at least partly, from impairment of the development and/or survival of IL-17A/F-producing T cells, the underlying mechanisms of which remain unknown (28,52). Patients with these mutations, who had long been known to be prone to thyroid autoimmunity, were recently found to display other infectious and autoimmune phenotypes (16,17,23,37,51).…”