Ocular microbial diversity, community structure, and function at high altitude

Abstract

Purpose: To investigate the composition and function of ocular surface microbiome in healthy people from different altitudes.

Methods: Thirty-two healthy people living in a high altitude region and 30 sex- and age-matched individuals living in a low altitude region were enrolled. Samples were collected from the lower conjunctival sac of one randomly chosen eye for each participant. 16S rRNA sequencing was conducted to study the bacterial community composition and predict gene function using PICRUSt software.

Results: Microbial diversity and richness was significantly decreased in samples from highlanders as calculated by Abundance-based Coverage Estimator (ACE) index, Chao1 index, and observed-species index (all p < 0.01). Principle coordinate analysis (PCoA) suggested significantly distinct clustering of the conjunctival sac bacterial communities between two groups (p = 0.03), especially the dominant genera. The relative abundances of Corynebacterium, Staphylococcus, and Anaerococcus were significantly enriched in highlanders, while those of Pseudomonas and Massilia were significantly decreased as compared with lowlanders (p < 0.01). In the functional annotation analysis, we found that 74 gene pathways, mainly in metabolism, differed in abundance. Pathways related to immune system diseases and infectious diseases were also enriched in highlanders.

Conclusion: The composition and function of ocular surface microbiome in highlanders were distinct from those of lowlanders and our study may provide a reference catalog of the healthy conjunctival microbiome in highlanders.

Keywords: 16S rRNA gene sequencing; Healthy conjunctiva; Microbial communities; Ocular surface; PICRUSt.