Elevated Kocuria rhizophila contributing to repair of skin barrier function in patients with atopic dermatitis

Recent findings suggest skin microbiota is closely linked to the aggravation of atopic dermatitis (AD) and skin barrier dysfunction.

This prospective cross-sectional study included 52 children: 35 with AD flare (F) and non-flare (NF), and 17 without AD (non-AD). Microbes in the skin samples from the three groups were analyzed using 16S rRNA amplicon sequencing. We estimated the anti-virulence of Kocuria rhizophila in the skin microbiome of children. The effects of K. rhizophila were evaluated in human skin cell models with AD-like damage caused by Staphylococcus aureus secretory toxins, including protein A (PA), lipoteichoic acid, and protease V8.

Taxonomic classification revealed significant phylum-level differences among the three groups. Alpha-diversity indices tended to decrease in the AD-F group compared with the non-AD group but were higher in the AD-NF group. The AD group had a high relative abundance of S. aureus, but S. aureus was almost absent in the non-AD group and exhibited a marked decrease in the AD-NF group; K. rhizophila was negatively correlated with AD severity. Heat-killed K. rhizophila (HKKR) treatment upregulated gene expression of the tight junction protein zonula occludens-1 and critical components of the cornified cell envelope, involucrin and filaggrin, while downregulating the expression of the pro-inflammatory cytokines interleukin (IL)-1b and IL-6. Transcriptomic analysis revealed that HKKR treatment was associated with skin barrier functions, cell-cell junctions, and immune responses.

K. rhizophila may be associated with the mitigation of skin barrier dysfunction and inflammation in S. aureus infection, highlighting its potential for AD treatment.