THE INFLUENCE OF ENVIRONMENTAL FACTORS ON NONALCOHOLIC FATTY LIVER DISEASE AND OBESITY

Non-alcoholic fatty liver disease (NAFLD) is the most common kind of liver injury in the world and its prevalence is due to the lack of “in-time” diagnosis and, as a consequence, treatment. A lot of different diseases are complicated by the fatty liver infiltration, the most often is obesity. The progress of the disease could depend on the environmental factors and the genetic disabilities. The aim of the review article was to analyze the latest data about the factors which impact on the NAFLD development in obese patients, including the gut microbiota, genetic predictors and environmental components, to find the new ways of pathogenesis, diagnosis and treatment. Non-alcoholic liver steatosis is diagnosed in 70% of obese patients (although some authors report a significantly higher (up to 95%) incidence of cases) and 35% of thin patients, and non-alcoholic steatohepatitis (NASH) – in 18.5% of obese patients and 2.7% – with insufficient body weight. Among patients with severe obesity and BMI more than 35 kg/m2, the prevalence of NAFLD and NASH is 91% and 37%, respectively. The combination of facts, available at the moment, suggests that one of the central role in the NAFLD development plays disturbance of intestinal microbiota and its permeability. Intestinal microflora can affect the NAFLD due to three mechanisms: 1) an increase in ethanol production in the intestinal cavity; 2) metabolic disorders of food choline (necessary for the synthesis of very low-density lipoproteins and elimination of liver lipids); 3) the release of bacterial lipopolysaccharides. The diagnostic methods, which allow investigation of fatty liver infiltration in the early stages, are considered. Despite the lower sensitivity and specificity compared with CT, ultrasound is considered as an acceptable first-line procedure for diagnostic NAFLD in clinical practice. The waist cir1 Ph.D, Associate Professor, Danylo Halytsky Lviv National Medical University, Ukraine 2 Ph.D, Associate Professor, Shupyk National Medical Academy of Postgraduate Education, Ukraine © Kvit Khrystyna, Kharchenko Viacheslav 97 The influence of environmental factors on nonalcoholic fatty liver disease. cumference, the liver obesity index (IOP), and lipid accumulation products is closely related to the IP, indicate liver steatosis and may be useful for large screening among the general population instead of ultrasound. At present, there is no specific therapy for NAFLD in combination with obesity. Diet modulation and life style modification are the important part of treatment. Given the fact that the key mechanism in the progress of NAFLD and obesity is the IR, the use of pharmacological agents that have a positive effect on the sensitivity of tissues to insulin, – insulin sensitizers, is confirmed. Taking into account, that there are no specific drugs for the NAFLD treatment, the study of the intestinal microbiota influence on the pathogenesis and progress of this disease may have new therapeutic perspectives. In particular, the modulation of the intestinal microbiota can be achieved by the use of prebiotics, probiotics, selective intestinal antibiotics (rifaximin), and fecal microbiota transplantation. Introduction Nonalcoholic Fatty Liver Disease (NAFLD) is a chronic metabolic, stress-induced liver disease associated with insulin resistance in patients who do not consume alcohol in hepatotoxic doses (more than 40 g of pure ethanol for men and 20 g for women per day). Today NAFLD becomes one of the most common chronic liver diseases around the world. The modern notion of NAFLD includes the range of liver lesions that are differed by clinical and histological changes: steatosis, steatohepatitis, and fibrosis. Liver steatosis, usually, has a benign course and does not correlate with mortality, whereas progression of this disease to non-alcoholic steatohepatitis (NASH) increases the risk of forming liver cirrhosis and liver failure [6]. Population surveys suggest that 60-80% of cryptogenic liver cirrhosis is a consequence of NASH. Since NASH's term was first proposed by J. Ludwig in 1980, the prevalence of NAFLD has increased in parallel with the dramatic obesity and diabetes increase in the population, and is now the most common cause of liver disease in the world. NAFLD is closely linked to insulin resistance (IR), obesity and is recognized as a liver manifestation of metabolic syndrome (MS). The association of NAFLD with obesity, especially abdominal, metabolic syndrome and various metabolic markers of the risk of developing cardiovascular diseases and type 2 diabetes mellitus (DM type 2) directly affects the prognosis of the underlying diseases, as well as the life duration of obese patients [11].