Chronic mucocutaneous candidiasis in APECED or thymoma patients correlates with autoimmunity to Th17-associated cytokines

Abstract

Chronic mucocutaneous candidiasis (CMC) is frequently associated with T cell immunodeficiencies. Specifically, the proinflammatory IL-17A-producing Th17 subset is implicated in protection against fungi at epithelial surfaces. In autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED, or autoimmune polyendocrine syndrome 1), CMC is often the first sign, but the underlying immunodeficiency is a long-standing puzzle. In contrast, the subsequent endocrine features are clearly autoimmune, resulting from defects in thymic self-tolerance induction caused by mutations in the autoimmune regulator (AIRE). We report severely reduced IL-17F and IL-22 responses to both Candida albicans antigens and polyclonal stimulation in APECED patients with CMC. Surprisingly, these reductions are strongly associated with neutralizing autoantibodies to IL-17F and IL-22, whereas responses were normal and autoantibodies infrequent in APECED patients without CMC. Our multicenter survey revealed neutralizing autoantibodies against IL-17A (41%), IL-17F (75%), and/ or IL-22 (91%) in >150 APECED patients, especially those with CMC. We independently found autoantibodies against these Th17-produced cytokines in rare thymoma patients with CMC. The autoantibodies preceded the CMC in all informative cases. We conclude that IL-22 and IL-17F are key natural defenders against CMC and that the immunodeficiency underlying CMC in both patient groups has an autoimmune basis.

Figure 1.

Decreased IL-17F and IL-22 responses associate with CMC in APECED patients. (A) Secretion of IL-17A, IL-17F, and IL-22 by PBMCs from APECED patients without (CMC−) or with (CMC+) CMC and age-matched controls (Ctrl, n = 14 at 72-h time points) after stimulation with heat-killed C. albicans hyphae or SEB for 72 h was measured by ELISA. The patients are detailed in Table I. (B) SEB-stimulated PBMCs were stained intracellularly for IL-17A and IL-22 and FACS analyzed. Horizontal bars represent median values. A Kruskal-Wallis test was used to compare the group medians. This figure represents three independent experiments. Each symbol corresponds to a value obtained from an individual.

Figure 2.

Disease-specificity of autoantibodies to IL-17A, IL-17F, and/ or IL-22. (A–C) Autoantibodies binding human IL-17A, IL-17F, and/ or IL-22 in sera from APECED or thymoma patients and disease or healthy controls tested by ELISA. (D and E) Comparisons of neutralizing and binding activity of anti–IL-17A and anti–IL-17F. (F) Because ELISA underestimates antibodies against IL-22, we used neutralizing assays for systematic comparisons. 12 sera were exhausted before exact titration of anti-IL-22 could be done. Red and black bars indicate group medians. SLE, systemic lupus erythematosus; RA, rheumatoid arthritis. Open circles represent patients T1 and T2 (Fig. 3 C and Table S2).

Figure 3.

Autoimmunity to Th17-related cytokines is associated with CMC and cytokine productivity in vitro. (A) Associations between CMC and anti-cytokine autoantibodies in APECED patients. Red bars indicate group medians. (B) Representative FACS plots for intracellular IL-22 and IL-17A in a healthy subject (left) or in APECED patients with CMC and antibodies against IL-22 alone (middle) or against both IL-17A and IL-22 (right) after 6 h of SEB stimulation. (C) Production of IL-17A, IL-17F, and IL-22 by C. albicans– and SEB-stimulated (72 h) PBMCs from five random myasthenia gravis/thymoma patients was measured with ELISA. Patients T1 (X) and T2 (O) proved to be the only two with CMC. Median values for healthy controls are indicated with gray bars. (D) The concentration of secreted IL-17F (left) and IL-22 (right) after stimulating APECED patients’ PBMCs with SEB (for 72 and 18 h, respectively) correlates negatively with the respective neutralizing antibody titer. (E) Normal naive T cells were differentiated to Th17 cells with IL-1β, IL-6, IL-23, and IL-21 in the presence of sera (1:10) from either controls or APECED patients with antibodies to IL-22, IL-17F, and/or IL-17A. The IL-22– and IL-17A–producing cells were enumerated by flow cytometry. Data are representative of three independent experiments. Horizontal bars show median values.