Assessment of the intestinal microbiota and fecal short-chain fatty acids content in children with non-alcoholic fatty liver disease

Background. Changes in the intestinal microbiome trigger the development and progression of non-alcoholic fatty liver disease (NAFLD). Adverse fluctuations in intestinal microbiota are associated with increased intestinal permeability, activation of mucosal and adaptive immunity, increase in production and intestinal absorption of short-chain fatty acids (SCFA). The ratio of acetic, propionic, butyric acid is an important indicator of the integrity of the microbial community of the intestine. Thus, the study of the gut microbiota composition and short-chain fatty acids production represents a very appealing approach to increasing our knowledge about the mechanisms leading to NAFLD in children. The purpose of the study was to determine the features of the fecal short-chain fatty acids (fSCFA) content and the colonic microbiota composition in children with NAFLD. Materials and methods. A comprehensive examination of 102 children was provided in the Department of Pediatric Gastroenterology of the Institute of Gastroenterology of the National Academy of Medical Sciences of Ukraine. According to the presence of obesity, transient elastography data and alanine aminotransferase levels the patients were divided into four groups: I group — children with simple hepatic steatosis (n = 24); II group — children with nonalcoholic steatohepatitis (NASH) (n = 14); III group — children with obesity without steatosis (n = 48), IV group — children with normal weight (n = 16). Chromatographic study of fSCFA was conducted using gas chromatograph Chromatec-Crystal 5000. The microorganisms were identified using a microbiological study of the colon content. Diagnosis of NAFLD was established with FibroScan 502 Touch (Echosens, France) with the determination of the controlled attenuation parameter. Results. Significant changes in the spectrum of fSCFA were observed in children of the III group with acetic acid content increased by 4.8 times (р < 0.05), propionic acid by 1.5 times (р < 0.001), and butyric acid by 1.7 times as compared to the control group, while in children with NASH, acetic content was 2.5-fold increased, propionic and butyric acid — 1.4-fold in comparison with the control group (p = 0.1). Also, significant anaerobic index decrease was observed in NAFLD patients. The fecal content microbiological examination demonstrated the reduced level of Bifidobacteria strains in 11.8 % patients of group I and in 8.3 % of group III; decreased levels of Lactobacillus were found in 70.6 % children of group I, in all children with NASH, in 70.8 % patients of group III. Overgrowth of bacteria such as Klebsiella was identified in 23.5 % patients of group I and in 8.3 % people of group III. Pathogenic Staphylococcus was detected in 5.9 % patients of group I, in 8.3 % patients of group III. Overgrowth of Candida was detected in 23.5 % children of group I, in 14.3 % children of group II and in 20.8 % children of group III. Conclusions. Quantitative and qualitative deviation of intestinal microbiota such as a decrease in the number of major symbionts and an increase in the number of opportunistic microflora was observed in children with NAFLD and obesity. Changes in the SCFA spectrum were found in obese children assuming the importance of intestinal microflora disorders at the early stages of NAFLD development. The estimation of the ratio of SCFA fractions with the anaerobic index calculation can be useful to diagnose intestinal dysbiosis in children with NAFLD.