Trajectory of age-associated changes in small intestinal microbial community of healthy person metaorganism

The study of the small intestinal microbiota in humans is complicated due to the low availability of biomaterial. Non-invasive methods of metabolomics and bioinformatic data analysis can expand our understanding of the small intestinal microbiota structure and its role in maintaining body homeostasis. Here we assess the trajectory of age-related changes in the small intestinal microbial community of healthy individuals in the context of metaorganism-wide interaction between cytokine and neuroendocrine systems, by using the methods of gas chromatography mass spectrometry of microbial markers (GCMS MM) and optimal scaling. 110 apparently healthy children, adults and elderly individuals were enrolled to the study. The main types of the small intestine microbiota (Bacteroidetes, Firmicutes, Actinobacteria, Proteobacteria, and Fusobacteria) were quantified in peripheral blood by the GCMS MM method. To construct age-related trajectories of changes in the small intestinal microbiota and parameters of cytokine and neuroendocrine systems, the optimal scaling technique based on the multivariate Gifi transformation (CATPCA method) was used. It was found, that the small intestinal bacterial community of both children and seniors contained significantly lowered total number of microorganisms due to the low number of bacteria of Firmicutes and Actinobacteria types along with high number of members of Proteobacteria and Fusobacteria types compared with adults. Assessment of the trajectory of age-associated changes in microbiota of the small intestine showed that 1) children have strong dynamic fluctuations in the number and links within microbial community along with formation of links between the main regulatory immune and neuroendocrine systems of the metaorganism, 2) adults display plasticity and consistency in functioning of immune and nervous systems that determine the state of dynamic balance of the small intestinal microbiota, 3) healthy aging is characterized by high degree of cooperation between the main members of the bacterial community, which ensures system stability at new level, as one of the mechanisms of host adaptation. Thus, using methods of GCMS MM and optimal scaling, allows us to expand our understanding about age-associated trajectory of changes in the small intestinal microbiota and its cooperation with immune and neuroendocrine systems within the metaorganism, which can be used to develop new methods of therapy for infectious and non-infectious diseases.