Research from China reveals geolocation impact on skin’s microbiome

14 Dec 2023 --- New research investigates how environmental stressors per region affect the skin’s microbiome. Characterization of the skin microbiome of individuals from different geographic regions will help to understand the factors behind the prevalence of skin disorders and support skin care product development, suggest the researchers.

Facial skin is more exposed to the outside environment, and it is usually affected by environmental factors. The study highlights the effects of geographic factors on skin microbial structures and skin lipids, especially fatty acids and ceramides.

The study consisted of volunteers from northern, southern and northwestern China aged between 18 and 60 years. The participants included 25 volunteers from Beijing in North China, 23 volunteers from Zhangye, Gansu Province in Northwest China and 23 volunteers from Suzhou, Jiangsu Province in South China between August 2022 and October 2022. 

Location versus lipids
The three geographic regions are representative of the major climates in China. Gansu, in the northwest plateau, has a temperate continental monsoon climate with hot and dry summers, cold and dry winters, low annual precipitation and high UV radiation. 

Suzhou, in the south, has a subtropical monsoon climate with hot and humid summers, warm and wet winters, high annual precipitation and lower UV radiation. 

Ceramide levels were discovered to be lower in skin samples from the southern region of China.Beijing, in northern China, has a temperate monsoon climate, which is characterized by hot and humid summers, cold and dry winters and relatively moderate annual precipitation and UV radiation. 

Facial skin samples were collected for amplicon sequencing and metabolomic liquid chromatography-mass spectrometry analyses. The researchers demonstrated significant alterations in the abundance of multiple microorganisms and skin lipid compositions between individuals.

The ceramide level was lower in skin samples from the southern region than in those from the northern and northwestern regions. The total level of fatty acids was lower in samples from the northwest than in those from the north. 

Several long-chain fatty acids, such as palmitic acid, docosanedioic acid, oleic acid and behenic acid, were significantly enriched in samples from the northwest compared to other regions. 

However, levels of total eicosanoid and its several family members, prostaglandins, and leukotrienes, which are considered mediators of allergic diseases, were significantly decreased in samples from the northwest. 

The research analyzed the correlation between microorganisms and skin lipids, including fatty acids, ceramides and eicosanoids. Malassezia, a lipophilic yeast, was strongly positively correlated with eicosanoids and several medium- to long-chain fatty acids, such as behenic acid and palmitic acid but it was negatively correlated with ceramides. 

In contrast, other skin residential microorganisms, such as Candida, Aspergillus, Alternaria, Cladosporium and Lactobacillus, showed opposite correlation trends, including a positive correlation with ceramides and a negative correlation with eicosanoids. Cutibacterium, another well-known lipophilic bacterium, was not correlated with total lipids, fatty acid derivatives or ceramides.

Results in bacteria
The indexes of the bacterial community were not different between different geographic regions. Nonmetric multidimensional scaling analysis of the bacterial community did not reveal distinct clustering among groups.

People living in the northwest, a dry climate with high altitude, showed lower levels of total lipids and lower abundance of malassezia but higher levels of ceramides and fatty acids. Residents of the northwest of China, which has a dry climate and high altitude, showed lower levels of total lipids in their skin.

Malassezia had a positive correlation with eicosanoids and a negative correlation with ceramides. Malassezia was found to dominate the fungal community in all samples, and its relative abundance was significantly higher in samples from the north and south than in those from the northwest. 

Correlation analysis showed the female sex was correlated with a higher proportion of malassezia on the skin, whereas skin type was not correlated with malassezia.

Firmicutes, actinobacteria and proteobacteria, were the predominant bacterial divisions on the facial skin in all geographic regions. The relative abundances of staphylococcus and Cutibacterium were significantly higher in samples from the north. 

Cutibacterium, a lipophilic bacterium, showed higher relative abundance in subjects with the oiled skin type than in those with other skin types. Further correlation analysis showed that age was positively correlated with chryseobacterium and negatively associated with staphylococcus and cutibacterium.

The relative abundances of cladosporium, candida, aspergillus, fusarium, alternaria, Penicillium, mortierella and Filobasidium were significantly increased in samples from the northwest compared with those from other regions. 

Building on research
The research follows a landmark study on the topographical and temporal diversity of the human skin microbiome. A growing number of studies have focused on this area. 

Several infectious, inflammatory and neoplastic dermatoses are associated with shifts in the skin microbial composition. Until now, single-center studies have profiled the human skin microbiome under healthy and diseased states, whereas there is a lack of studies on the effects of environmental factors on the healthy microbiome.

 By Sabine Waldeck