Two Novel Gain-of-Function Mutations of STAT1 Responsible for Chronic Mucocutaneous Candidiasis Disease: Impaired Production of IL-17A and IL-22, and the Presence of Anti–IL-17F Autoantibody

Abstract

Heterozygous gain-of-function (GOF) mutations of STAT1 are responsible for chronic mucocutaneous candidiasis disease (CMCD), one of the primary immunodeficiency diseases characterized by susceptibility to mucocutaneous Candida infection. To date, 30 aa changes have been reported: 21 in the coiled-coil domain and 9 in the DNA-binding domain. In this study, we report two novel STAT1 GOF mutations of p.K278E in coiled-coil domain and p.G384D in DNA-binding domain in Japanese CMCD patients. Ectopic expression of these STAT1 mutants in HeLa cells was associated with increased phosphorylation of the mutant and the endogenous wild-type STAT1 due to impaired dephosphorylation, indicating heterodimers of the wild-type and mutant STAT1 cause impaired dephosphorylation, as did homodimers of the mutants. Because IL-17A production was not significantly reduced at least in one of the patients following PMA plus ionomycin stimulation, we further studied Th17-associated cytokines IL-17A, IL-17F, and IL-22 in response to more physiologically relevant stimulations. IL-17A and IL-22 production from PBMCs and CD4(+) cells was significantly reduced in four patients with STAT1 GOF mutations, including the previously reported R274Q in response to anti-CD3 plus anti-CD28 Abs or Candida stimulations. In contrast, IL-17F production was comparable to healthy controls in response to anti-CD3 plus anti-CD28 Abs stimulation. These results indicate impaired production of IL-17A and IL-22 rather than IL-17F was associated with the development of CMCD in these patients. Additionally, only the anti-IL-17F autoantibody was detected in sera from 11 of 17 patients with STAT1 GOF mutations, which may be useful as a marker for this disease.

Impaired natural killer cell functions in patients with signal transducer and activator of transcription 1 (STAT1) gain-of-function mutations

“…40 In patients with CMCD, STAT1 GOF mutations are associated with a characteristic delay of protein dephosphorylation, resulting in persistent activation of the signaling pathway. 5,18,24,25 In our study the time course analysis of STAT1 phosphorylation in response to IFN-a has shown a similar pattern in NK cells of patients with STAT1 GOF mutations. However, we have also observed that both resting and IL-2-activated NK cells of these patients display increased STAT1 protein levels and higher expression of STAT1 mRNA, suggesting that augmented STAT1 protein levels might concur with the increased response of NK cells to cytokines signaling throughout STAT1.…”

“…This observation is in accordance with previous studies showing a characteristic delay of STAT1 dephosphorylation. 5,18,24,25 Moreover, we investigated STAT1 protein levels in primary resting NK and T cells from patients with STAT1 GOF mutations. Surprisingly, flow cytometric analysis of STAT1 protein showed a 3-fold increase in STAT1 protein levels in resting NK and T cells from patients compared with protein levels detected in cells of healthy control subjects (Fig 1, F, and see Fig E1, E).…”

Heterozygous STAT1 gain-of-function mutations underlie an unexpectedly broad clinical phenotype

“…CMC typically begins in early childhood, although it may first present up to the third decade of life, and signs and symptoms varied within and between families. 20 In these patients, CMC is most likely the consequence of impaired IL-17A and IL-17F immunity, [19][20][21]23,39,42,44 as it is also seen in patients with inborn errors of IL-17A/F immunity. [16][17][18] Circulating IL-17A-producing T cells counts are low in most but not all patients tested (82%).…”

Treatment of Chronic Mucocutaneous Candidiasis, an Unsolved Issue. Case Report and Literature Review

“…Some genetic etiologies of CMC have been well-described, mutations in some genes like: AIRE, STAT1, STAT3 (2,4,11,12,13,14,15,16,17) Other genetic syndromes are associated with far smaller numbers of cases, such as those due to mutations of IL-17RA, ACT1, IL-17F, PTPN22, CLEC7A, TLR3, CARD 9 (5,6,10,11,12,19,20,21,22,23). There are distinct forms of CMC for which the genetic defects have not yet identified (24).…”