Amino acids as biomarkers of phase сomposition of gallstones

Gallstone disease (cholelithiasis) remains one of the most common gastroenterological diseases worldwide. The formation of gallstones has not been fully studied due to the latent course of the initial stage of gallstone disease. The composition of gallstones is diverse. Among the substances present in gallstones, the least studied is the protein component, the structural units of which are amino acids. In this connection, the main goal of the study was to identify patterns of changes in the amino acid composition of gallstones of various phase compositions. The objects of the study were 23 samples of gallstones belonging to residents of the Komi Republic. Data analysis was carried out by statistical one-dimensional and multidimensional methods. The statistical analysis, used in this work to study pathogenic formations in the human body, revealed qualitatively new, previously unremarked features of the amino acid composition of gallstones, which indicated the difference in the protein component and its relationship with the phase composition of gallstones. According to the results of cluster analysis by the contents of all amino acids, the studied gallstones were grouped into three different phase compositions of the type — cholesterol, cholesterol with a mineral component, and pigment. The Mann-Whitney and Student’s criteria established that all three types of gallstones were statistically significantly (p <0.05) pairwise different in the contents of alanine, valine, isoleucine, leucine, proline, phenylalanine, aspartic and glutamic acid. The lowest contents of the amino acids were determined in cholesterol gallstones, the highest — in pigment ones. The multidimensional method of classification trees also revealed individual amino acids phenylalanine, proline, leucine, according to which gallstones of different phase compositions were clearly separated by type. Based on the results obtained by statistical methods, special attention should be paid to Phenylalanine acid most clearly compared gallstones of different phase composition in comparison with others. The established relationships can be used to predict the type of cholelithiasis, to solve the problem of gallstones formation and metaphylaxis.