Impaired dendritic cell maturation and cytokine production in patients with chronic mucocutanous candidiasis with or without APECED

Abstract

Patients with chronic mucocutaneous candidiasis (CMC) suffer persistent infections with the yeast Candida. CMC includes patients with autoimmune regulator (AIRE) gene mutations who have autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED), and patients without known mutations. CMC patients have dysregulated cytokine production, and dendritic cells (DCs), as central orchestrators, may underlie pathogenic disease mechanisms. In 29 patients with CMC (13 with APECED) and controls, we generated monocyte-derived DCs, stimulated them with Candida albicans, Toll-like receptor-2/6 ligand and lipopolysaccharide to assess cytokine production [interleukin (IL)-12p70, IL-23, interferon (IFN)-gamma, IL-2, tumour necrosis factor (TNF)-alpha, IL-6, transforming growth factor-beta, IL-10, IL-5, IL-13] and cell-surface maturation marker expression (CD83, CD86, human leucocyte antigen D-related). In both APECED and non-APECED CMC patients, we demonstrate impairment of DC function as evidenced by altered cytokine expression profiles and DC maturation/activation: (1) both groups over-produce IL-2, IFN-gamma, TNF-alpha and IL-13 and demonstrate impaired DC maturation. (2) Only non-APECED patients showed markedly decreased Candida-stimulated production of IL-23 and markedly increased production of IL-6, suggesting impairment of the IL-6/IL-23/T helper type 17 axis. (3) In contrast, only APECED patients showed DC hyperactivation, which may underlie altered T cell responsiveness, autoimmunity and impaired response to Candida. We demonstrate different pathogenic mechanisms on the same immune response pathway underlying increased susceptibility to Candida infection in these patients.

Fig. 1

Non-autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) patients produce very high interleukin (IL)-6 but low IL-23 levels in response to Candida-specific stimuli. Immature monocyte-derived dendritic cells (moDCs) from patients and controls were either left unstimulated or treated with C. albicans hyphae, a specific Toll-like receptor (TLR)-2/6 ligand or lipopolysaccharide (LPS). Culture supernatants were collected at 24 h and measured by meso scale discovery (MSD) multiplex assay for detection of IL-6 or enzyme-linked immunosorbent assay for detection of IL-23. Note log scale for LPS. The level of significance was set at P < 0·05. Average values are presented as medians with interquartile ranges (IQR). (a) Increased production of IL-6. Detection limit (----) was 3 pg/ml. (b) Decreased production of IL-23. Detection limit (----) was 15 pg/ml.

Fig. 2

Impaired upregulation of CD83 in both autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) and non-APECED children in response to Candida albicans. Immature monocyte-derived dendritic cells (moDCs) were cultured overnight with either the hyphal form of C. albicans, a specific Toll-like receptor (TLR)-2/6 ligand, lipopolysaccharide (LPS) or were left untreated. After 24 h, moDCs were harvested, stained with anti-CD83-phycoerythrin (PE) and analysed by flow cytometry for CD83 expression. The level of significance was set at P < 0·05. Average values are presented as medians with interquartile ranges (IQR). (a) Percentage of cells. (b) Median fluorescence intensity (MFI).

Fig. 3

Monocyte-derived dendritic cells (moDCs) from autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) patients express higher CD86 levels than controls. Immature monocyte-derived dendritic cells (DCs) were cultured overnight with either the hyphal form of Candida albicans, a specific Toll-like receptor (TLR)-2/6 ligand, lipopolysaccharide or were left untreated. After 24 h, DCs were harvested, stained with anti-CD86-fluorescein isothiocyanate (FITC) and analysed by flow cytometry for CD86 expression. The level of significance was set at P < 0·05. Average values are presented as medians with interquartile ranges (IQR). (a) Percentage of cells. (b) Median fluorescence intensity (MFI). Note log scale.