Linking the westernised oropharyngeal microbiome to the immune response in Chinese immigrants

Human microbiota plays a fundamental role in modulating the immune response. Western environment and lifestyle are envisaged to alter the human microbiota with a new microbiome profile established in Chinese immigrants, which fails to prime the immune system. Here, we investigated how differences in composition of oropharyngeal microbiome may contribute to patterns of interaction between the microbiome and immune system in Chinese immigrants living in Australia.

We recruited 44 adult Chinese immigrants: newly-arrived (n = 22, living in Australia < 6 months) and long-term Chinese immigrants (n = 22, living in Australia > 5 years), with age and gender matched. Oropharyngeal swabs, serum and whole blood were collected. The 16 s ribosomal RNA gene from the swabs was sequenced on the Illumina MiSeq platform. Innate immune responses were determined by 23 Toll-like receptors (TLR) pathway cytokines, while adaptive immune responses were determined by IgG-associated response to specific microbial/viral pathogens.

The relative abundance of the genus Leptotrichia was higher in long-term immigrants as compared to that in newly-arrived Chinese immigrants, while the genus Deinococcus was significantly lower in long-term Chinese immigrants. The genera uncultured Lachnospiraceae, Erysipelotrichaceae UCG-007, Veillonella, and Actinomycetales_ambiguous taxa were negatively correlated with cytokine IL-6 in long-term Chinese immigrants (rho range: - 0.46 ~ - 0.73). With respect to adaptive immunity, several microbial taxa were significantly associated with IgG1 responsiveness to microbial antigens in long-term immigrants, while a significant correlation with IgG1 responsiveness to viral antigens was detected in newly-arrived immigrants.

The composition of the oropharyngeal microbiome varies between newly-arrived and long-term Chinese immigrants. Specific microbial taxa are significantly associated with immunological parameters but with different association patterns between newly-arrived and long-term Chinese immigrants.