Molecular Analysis of Fungal Microbiota in Samples from Healthy Human Skin and Psoriatic Lesions

Abstract

Psoriasis, a common cutaneous disease of unknown etiology, may be triggered by infections, including those due to fungi. Since the fungal community of human skin is poorly characterized, we aimed to analyze the mycological microbiota in healthy skin and psoriatic lesions. Twenty-five skin samples from five healthy subjects (flexor forearm) and three patients with psoriasis were analyzed using broad-range 18S ribosomal DNA (rDNA) and 5.8S rDNA/internal transcribed spacer 2 (ITS2) Malassezia-specific PCR primers. Broadrange PCR analysis indicated that most organisms resembled Malassezia. Malassezia-specific 5.8S/ITS2 analysis of 1,374 clones identified five species and four unknown phylotypes, potentially representing new species. The species distribution appears largely host specific and conserved in different sites of healthy skin. In three subjects, the Malassezia microbiota composition appeared relatively stable over time. Samples of Malassezia microbiota from healthy skin and psoriatic lesions were similar in one patient but substantially different in two others. These data indicate the predominance of Malassezia organisms in healthy human skin, host-specific variation, stability over time, and as yet, no consistent patterns differentiating psoriatic skin from healthy skin.Human skin is colonized by diverse microbiota, including bacteria and fungi, that can be pathogenic under particular circumstances (14, 16). Traditionally, microorganisms have been identified by culture-dependent methods; however, many species are fastidious and underrepresented in cultures from mixed microbial communities (13), whereas others cannot be cultivated under known conditions (2). Therefore, culture-independent molecular techniques have been used for the identification of microbial species within ecosystems (2, 9, 27, 42).Such methods, particularly the analysis of rRNA genes, have been employed to characterize bacterial and fungal communities associated with diverse human body sites, including intestine (11), gingiva (28,33,43), esophagus (45), vagina (65), and outer ear canal (13). As predicted, these studies revealed greater diversity, including previously undescribed organisms, than did previous analyses based on culture-dependent techniques.The application of molecular techniques has been advocated to characterize the microbiota in both healthy and diseased skin (14). To date, rRNA data have been used to identify species associated with fungal dermatoses (21,29,38,39) and PCR-based diagnostic tests have been developed (15,26,62). Psoriasis, a common dermatosis affecting about 3% of the population in industrialized countries (3), is characterized by erythrosquamous cutaneous lesions associated with abnormal patterns of keratinocyte growth and differentiation (35). Although of unknown etiology, trigger factors, including physical trauma and streptococcal infections, may provoke clinical manifestations (51). Fungal organisms, including Candida albicans (63) and Malassezia furfur (3), have also been associated with the developmen...

A systematic literature review of the human skin microbiome as biomarker for dermatological drug development

“…An increased diversity in the fungal flora in psoriatic skin lesions, compared to healthy skin was reported by Paulino et al . 25 and Amaya et al . 26.…”

“…In 10 studies, the cutaneous microbiome in PV patients was investigated, Table 1 25, 26, 27, 28, 29, 30, 31, 32, 33, 34. In addition to microbiota, these studies have focused on the mycobiota.…”

Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics

“…The ability to increase water retention on the skin and reduce erythema formation is an emerging attribute of GOS ingestion, as reported in mouse studies 68 . On the skin, application of a prebiotic might stimulate changes in bacterial 69 or fungal 70 profiles perhaps by targeting epidermal growth factor receptor. The health consequences of this approach are currently unclear, but might include psoriasis, acne, dermatitis, eczema and wound development 66,67,71 .…”

Malassezia furfur fingerprints as possible markers for human phylogeography

“…Generally, data on skin Malassezia population dynamics are scant (Paulino et al, 2006) and not directly comparable. Yet, indicative of the same phylogeographic trend is that a M. furfur seborrheic dermatitis isolate from a Dutch male residing for 5 years in China showed identical complete internal transcribed spacer sequences with M. furfur CBS7982, from a European healthy individual (Ran et al, 2008).…”