Microbial imbalance between the major bacterial-fungal populations colonizing dandruff scalps in Shanghai, China

In brief

Like on French individuals, dandruff scalps on Chinese individuals are associated with an unbalanced microbiome affecting the relative abundance of fungal and bacterial species. These community data support the hypothesis that rebalancing the dandruff scalp microbiota and restoring physiological ratios of fungal and bacterial species could be a common approach to improve dandruff condition in the two countries.

Introduction

Dandruff is a persistent and relapsing scalp disorder that affects about half of the world population. Abnormal flaking of the scalp, pruritus and minimal visible inflammatory reaction are hallmarks of dandruff. The pathophysiology of dandruff includes disrupted barrier function characterized by a decrease in hydration, an inflammatory signature and an abundance of yeasts Malassezia restricta and to a lesser extent, M. globose. A study performed on French individuals has shown that, compared to healthy scalps, dandruff was associated with an imbalance between three microorganisms: a higher abundance of M restricta and Staphylococcus epidermidis and a lower amount of Propionibacterium acnes.

Microbial disequilibrium in Chinese individuals with dandruff

Cloning and sequencing analysis performed on 41 Chinese individuals from the Shanghai area (32 with dandruff and 9 without dandruff) evidenced that in dandruff individuals there was no P. granulosum, , a more abundant and diverse Staphylococcal flora (S. caprae, S. epidermidis,S. capitis) and that M. restricta was the major species found on the scalp with and without dandruff (Figure 1).

Figure 1. Individual distribution of the main bacterial and fungal species on the scalp of Chinese volunteers N1‐N4 and D1‐D10: (a) distribution of 2214 sequences (~1500 bp) of 16S rDNA from dandruff and normal scalps; (b) distribution of 1818 sequences (~1500 bp) of ITS‐28S rDNA from dandruff and normal scalps. Results are presented as percentage (%) of the total sequences recovered per species per volunteer.

There were higher amounts of M. restricta and Staphylococcus spp. in dandruff scalps than in non‐dandruff scalps and the ratios of M. restricta to Propionibacterium and Staphylococcus to Propionibacterium were significantly higher in subjects with dandruff compared to those without dandruff.

Conclusion

Dandruff is associated with disequilibrium between the fungal and bacterial populations as compared to normal individuals. rebalancing the dandruff scalp microbiota could be a common approach to improve dandruff condition in France and in China.

Reference

Wang L et al. Exp Dermatol. 2015 May;24(5):398-400. Characterization of the major bacterial-fungal populations colonizing dandruff scalps in Shanghai, China, shows microbial disequilibrium.