Abstract
Skin aging is associated with changes in cutaneous physiology including interactions with a skin microbial community. A striking alteration and diversification in the skin microbiome with aging was observed between two different age groups of 37 healthy Japanese women, i.e. younger adults of 21–37 years old and older adults of 60–76 years old, using bacterial 16S rRNA gene sequencing. The analyses revealed that the alpha diversity/species richness was significantly higher in the older than the younger group for the cheek and forehead microbiomes, while the beta diversity in the overall structure significantly differed particularly for the forearm and scalp microbiomes between the two age groups. Taxonomic profiling showed a striking reduction in the relative abundance of the majority skin genus Propionibacterium in the cheek, forearm and forehead microbiomes of the older adults, and identified 38 species including many oral bacteria that significantly differentiated the two age groups with a skin site dependency. Furthermore, we found chronological age-related and unrelated skin clinical parameters that correlate with the observed changes in the skin microbiome diversity. Thus, our data suggested that the diversification of skin microbiomes in adult women was largely affected by chronological and physiological skin aging in association with oral bacteria.
Highlights
Our body’s largest organ, skin, is covered with various microorganisms, including fungi, bacteria, archaea and viruses[1], among which bacteria seem to outnumber others[2, 3]
The bacterial communities were analyzed in 148 skin samples from four skin sites of all subjects
The analysis identified a total of 38 species/operational taxonomic units (OTUs) showing significant changes in the linear discriminant analysis (LDA) score between them, of which 31 species were overrepresented in the older skin microbiomes, and other seven species, five of which were Propionibacterium species, were enriched in the younger skin microbiomes (Supplementary Table S4)
Summary
Our body’s largest organ, skin, is covered with various microorganisms, including fungi, bacteria, archaea and viruses[1], among which bacteria seem to outnumber others[2, 3]. Several studies have revealed that healthy skin microbiome is determined by skin micro-biotopes that include sebaceous, moist and dry environments[4, 5] In addition to these site effects, various host-related factors such as age and gender are shown to affect skin microbiome of healthy individuals[4]. Skin aging is characterized by a decrease in sweat, sebum and the immune functions resulting in significant alterations in skin surface physiology including pH, lipid composition and sebum secretion[12,13,14,15] These physiological changes provide potential alterations in the skin ecology that may affect the skin microbiome[16, 17]. The bacterial communities were evaluated based on the 16S rRNA gene sequence data obtained by high-throughput pyrosequencing
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