Estimation of the state of the microbiome in the elderly with impairments of carbohydrate and lipid exchange by the method of microbiome-associated exposomics

Abstract

We performed the biochemical analysis and studied the chemical composition of blood samples in 163 people 45-90 years old with type 2 diabetes mellitus and dyslipidemia. We examined the concentrations of the following compounds in the blood samples: fatty acids, aldehydes, styrenes of microbial origin, as well as the levels of glucose, triglycerides, cholesterol, and lipids of low and high density. The chemical composition of blood was determined by gas chromatography-mass spectrometry. The concentrations of fatty acids, aldehydes (including octadecenaldehyde (18a)), and styrenes were used to calculate the total molar concentration of small molecules originating from microbes (SMOM), of hydroxy acids - derivatives of the hydroxyl residue of Lipid A, and of bacterial endotoxin (3OH-FA), as well as grouped total concentrations of chemical compounds of microbial origin, which determine the representation of the main four phylotypes of the human microbiome: Actinobacteria, Bacteroidetes, Proteobacteria, and Firmicutes. Over the course of this study, we obtained data that show the increase in the total concentration of chemical compounds, the concentration of octadecenaldehyde and the concentration of 3OH-FA in patients with carbohydrate metabolism disorders due to diabetes mellitus type 2. We observed a decrease in the representation of Bacteroidetes in patients with carbohydrate metabolism disorders and a decrease in the representation of Proteobacteria and Firmicutes in patients with carbohydrate and lipid metabolism disorders, as well as an increase in the representation of Actinobacteria in patients with lipid metabolism disorders, including patients with combined lipid and carbohydrate metabolism disorders. There was a direct correlation between the representation of Bacteroidetes and the level of triglycerides in patients with type 2 diabetes mellitus as well as an inverse correlation between the representation of Firmicutes and glucose levels in these patients and in control group. We did not reveal statistically significant changes in the concentrations of microbial markers nor statistically significant correlations between the biochemical blood parameters and the representation of microbiome phylotypes in the blood of patients with lipid metabolism disorders.