Collapse of human scalp microbiome network in dandruff and seborrhoeic dermatitis

Taehun Park, Hye-Jin Kim, Nu Ri Myeong, Hyun Gee Lee, Ilyoung Kwack, Johnhwan Lee, Beom Joon Kim, Woo Jun Sul, Susun An

Abstract

This paper investigated the relationship between scalp microbiota and dandruff/seborrhoeic dermatitis, through bacterial and fungal community analyses on the scalp of 102 Koreans, performed using next‐generation sequencing technology Overall scalp microbiome composition differed significantly between the healthy scalp group and the diseased group. These findings provided novel insights into shifts of the microbial community relevant to dandruff/seborrhoeic dermatitis (D/SD).

Introduction

Staphylococcus, Propionibacterium and Malassezia are widely known as the cause of most scalp diseases in humans, including common dandruff and seborrhoeic dermatitis. One hypothesis is that the disturbed microbiome balance, such as a reduction in diversity and/or overgrowth of some species, may be associated with skin problems. In this study, the bacterial and fungal microbial communities associated with D/SD were investigated on scalps of 102 Koreans (59 women; 43 men), using the Illumina MiSeq sequencing platform. Scalp samples were collected by dermatologists and classified into three groups: (i) normal, adherent scalp flaking score (ASFS) <10; (ii) dandruff, ASFS ≥24; and (iii) SD, ASFS ≥24 with erythema. The analyses carried out aimed to find out (i) whether there was any difference in the microbiota between diseased scalps and healthy scalps, and (ii) whether the bacterial and fungal network collapsed in diseased scalps compared to normal scalps.

Results

Ascertaining the composition of human scalp microbial communities of dandruff (n=28) and seborrhoeic dermatitis (n=29) groups compared to normal (n=45) group There are considerably different bacterial and fungal communities between the normal group and the disease (D/SD) groups.
The bacterial richness was significantly higher in the disease groups than in the normal group, whereas the opposite was observed in fungal richness.
The dandruff and seborrhoeic dermatitis groups had a higher level of active folliculitis and pH but a lower level of hydration.
Relative abundances of two predominant bacteria, Staphylococcus and Propionibacterium, and of predominant fungi, Malassezia restricta and Malassezia globosa, behave inversely on the diseased scalp.
In the network analysis, the dandruff and seborrhoeic dermatitis groups showed lower connectivity and less complex bacterial and fungal networks than the normal group. The healthy scalp microbiota appeared to form more stable connections among dominant genus and species. It was also found that the disease groups had higher level of active folliculitis and pH but a lower level of hydration Interestingly, symptomatic factors (prickling, itching, pain and burning) were significantly correlated only to the bacteria community composition. In the scalp microbial community of the volunteers with these symptoms, some candidate bacteria were associated with these symptoms, including Hymenobacter and Deinococcus.

Conclusions

Differences were found between bacterial and fungal communities of the disease (D/SD) groups and the normal group. Through statistical analysis, it was concluded that these differences might be affected by the disease of the human scalp, whereby both the bacterial and the fungal communities were associated with the disorder; However, in this study physical pain in scalp diseases was related to the bacterial community. This may also indicate that bacteria, such as Bacteroides, Propionibacterium and Chryseobacterium, have a significant effect on the symptoms of the scalp disease.

Staphylococcus sp. and M. restricta were associated with a higher incidence of scalp disease, whereas Propionibacterium sp. and M. globosa were associated with normal scalps.
Therefore, the results not only provided information on the key‐stone species associated with dandruff and seborrhoeic dermatitis, but also on the importance of maintaining stability of the scalp microbiome.

Reference

Park T, Kim HJ, Myeong NR, Lee HG, Kwack I, Lee J et al. Collapse of human scalp microbiome network in dandruff and seborrhoeic dermatitis. Exp Dermatol. 2017;26:835–8.