Role of CD4+ T-cells in the pathology of non-alcoholic fatty liver disease and related diseases

Non-alcoholic fatty liver disease (NAFLD), which is considered a liver phenotype of metabolic diseases, is becoming a major cause of chronic liver disease. Multiple factors influence and interact with each other in a complex manner to form this pathological condition. As evidenced by low-grade chronic inflammation in obesity, which is a basic pathological feature of NAFLD, immune cell infiltration can occur in various organs, and immune cell infiltration into the liver plays an important role in the development of steatohepatitis. In recent years, an increasing number of reports indicate the involvement of innate immunity and adaptive immunity in the pathogenesis of NAFLD. CD4 + T-cells, which serve as an essential and complex element of the immune system and major regulators of host health and disease, are differentiated into functional T helper 1 (Th1), Th2, Th9, Th17, Th22, T follicular helper, and regulatory T-cells upon antigen stimulation in a special cytokine environment. In NAFLD patients, various pathological conditions such as obesity, diabetes, dyslipidemia, and adipose tissue inflammation coexist. Hence, T-cells can be affected by each of these pathological conditions. This review covers and discusses the reports on NAFLD and its associated pathologies as well as their effects on CD4 + T-cells.