Relationship of E. coli, Enterobacter spp. and S. aureus isolated from intestinal microflora with blood proteins associated with the digestive system during 3-day “dry” immersion

Abstract

There are several known mechanisms by which intestinal microflora (IM) is involved in the development of pathologies such as atherosclerosis, obesity, liver disease, diabetes mellitus, etc., for example, through the production of metabolites, induction of a systemic inflammatory response, modification of the functions of the immune system, changes in choline metabolism.

The purpose of this study is to study the relationship between the amount of proteins in the host’s blood and the number of opportunistic microflora (OM) in a model experiment with “dry” immersion, reproducing the physiological effects of weightlessness.

Materials and methods. 6 female volunteers aged from 25 to 40 years took part in the “dry” immersion experiment lasting 3 days. During the experiment, the subjects did not take antibacterial drugs or other medications that could affect IM. Capillary blood samples were obtained by puncture of the terminal phalanx of the ring finger 2 days before the start of the experiment and 2 days after the end. The amount of proteins was determined by mass spectrometry. Fecal samples were taken once 1-2 days before the start of the experiment and once on days 1-3 after the end to assess the number of microorganisms in the intestinal biotope.

Results. As a result of the studies, a correlation was revealed between the amount of OM in the IM and the amount of proteins in the blood: positive for E. coli, and negative for S. aureus and Enterobacter spp. The relationship between the level of proteins in the human blood and the number of intestinal OM was adequately described using a regression model in which a certain protein in the blood acted as a dependent variable, and the number of microorganisms acted as an independent variable. The identified proteins involved in significant correlations can be divided into several groups depending on their functions and locus of expression, and often proteins are included in several groups at the same time: 11 are expressed in the cells of the gastrointestinal tract, 22 in the cells of the glands of the digestive system. In general, proteins can be divided into two groups based on their function: structural and metabolic.

Conclusion. The obtained data indicate the existence of a close relationship between changes in the intestinal bacterial flora and the blood proteomic profile under the influence of “dry” immersion factors.