ABSTRACT
BACKGROUND: Although dysbiosis and the role of the microbiome in the pathogenesis of inflammatory skin diseases have been intensively investigated, fungal colonization or infection has received minimal attention. AIMS: To isolate and identify different fungal species namely Candida, Dermatophytes, Malassezia, and Aspergillus from plaque psoriasis patients, evaluate the association of IL-17A gene single nucleotide polymorphisms (SNPs) with psoriasis, and to reveal the relation between IL-17A gene SNPs and the fungal presence within the psoriatic plaques. PATIENTS/METHODS: Fifty plaque psoriasis patients and fifty healthy age and sex volunteers as controls were enrolled in this study. From psoriatic plaques, mycological isolation was done by direct microscopic examination (10% KOH mount), culture onto the three sets of media then species identification by phenotypic procedures. Genomic DNA extraction and genotyping for IL-17A (rs10484879) SNPs using polymerase chain reaction and restriction fragment length polymorphism were also done. RESULTS: Psoriasis cases showed higher frequency of fungal growth 86% vs. 14% in controls; (p < 0.001). The frequency of IL-17A GA, AA, and total polymorphism (GA+AA) genotypes in psoriasis cases was significantly higher than in controls. There was non-significant association between different IL-17A genotypes and fungal growth except Aspergillus flavus, which decreased gradually with GG, GA, and AA (37.5%, 20.8%, and 0%, respectively). CONCLUSIONS: Psoriasis cases are significantly associated with fungal growth, which may be a contributing factor in its pathogenesis. SNPs of IL-17A (rs10484879) G/A gene led to increased susceptibility toward pathogenesis of psoriasis. Fungal growth and IL-17A GA+AA genotypes are suggested to be independent predictors of psoriasis susceptibility.
