Molecular analysis of fungal microbiota in samples from healthy human skin and psoriatic lesions - PubMed (original) (raw)

Comparative Study

Molecular analysis of fungal microbiota in samples from healthy human skin and psoriatic lesions

Luciana C Paulino et al. J Clin Microbiol. 2006 Aug.

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. Broad-range 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.

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Figures

FIG. 1.

FIG. 1.

Fungal loci and sequences related to this study. (A) Schematic representation of the fungal ribosomal gene cluster, with PCR primers indicated (arrows). (B) Pairwise alignment between fragments of the 18S rRNA gene from human and representative fungal species, showing the sequences of primers EF4 and 1536 (long boxes). The human sequence contains a 7-bp insertion within the region represented by primer EF4 (small box). K, A/G; Y, T/C. (C) Pairwise alignment between fragments related to the 5.8S rRNA gene and ITS2 from humans and Malassezia species, showing the sequence of primers Mal1F and Mal1R. Bold letters in the human sequences refer to conserved nucleotides with the fungal sequences. H, T/C/A.

FIG. 2.

FIG. 2.

Neighbor-joining tree based on partial 18S rDNA sequences. The matrix of distances was calculated using the Jukes-Cantor algorithm. Bootstrap values are based on 500 replicates (values of at least 50% are shown). Organisms identified in this study are shown in bold. Codes correspond to GenBank accession numbers.

FIG. 3.

FIG. 3.

Neighbor-joining tree based on 5.8S rDNA and ITS2 sequences, showing the relationships among Malassezia organisms. The matrix of distances was calculated using the Jukes-Cantor algorithm. Bootstrap values are based on 500 replicates (values of at least 50% are shown). Organisms identified in this study are shown in bold. Codes correspond to GenBank accession numbers.

FIG. 4.

FIG. 4.

Consensus tree of hierarchical clustering of skin samples from healthy subjects (A) and patients with psoriasis (B). Height corresponds to Euclidian distance between samples. The number at each node represents the bootstrap value, based on 1,000 iterations. (A) 1N through 5N, healthy subjects; L, left arm; R, right arm. Samples L-Jan/R-Jan and L-Nov/R-Nov were obtained from the same site, 10 months apart. (B) 1P through 3P, patients with psoriasis; N, samples from normal skin; P1 through P3, samples from psoriatic lesions. Samples 1PP1A and 1PP1B were obtained from the same lesion, 6 months apart.

FIG. 5.

FIG. 5.

Scatterplot of the first two orthogonal principal axes based on the sample dissimilarity matrix. The samples from each subject are represented with the same color, and the sizes of the circles are proportional to the sample diversity, as determined by Rao's analysis. The diversity scale is shown in the upper right corner.

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