The immunoreactivity of TGF-β1 in non-alcoholic fatty liver disease

Introduction. Non-alcoholic fatty liver disease (NAFLD) is a common chronic liver disease which becomes a rapidly growing health problem in the Western countries. The development of the disease is most often connected to obesity. NAFLD is also considered as the hepatic manifestation of metabolic syndrome. Transforming growth factor beta 1 (TGF-beta 1) plays an important role in the pathogenesis of liver fibrosis, being involved in activation of hepatic stellate cells, stimulation of collagen gene transcription, and suppression of matrix metalloproteinase expression. The objective of the study was to evaluate by immunohistochemistry the expression of TGF-beta 1 in the liver tissue of NAFLD patients and correlate it with anthropometric, biochemical and routine histological parameters. Material and methods. The study group consisted of 48 patients with diagnosed NAFLD. Liver steatosis, NAFLD Activity Score (NAS) and METAVIR score of fibrosis were evaluated in liver biopsies. The immunoreactivity of TGF-beta 1 was evaluated semi-quantitatively separately in portal, septal, lobular hepatocytic and lobular sinusoidal liver compartments. The results were analyzed in regard to patients' clinical and biochemical parameters. Results. Neither steatosis nor NAS correlated with TGF-beta 1 expression in any liver compartment, whereas METAVIR score of fibrosis was associated with increased immunoreactivity of TGF-beta 1 in most of the studied liver compartments. TGF-beta 1 immunoreactivity showed positive correlation with patients' age and its expression in septal compartment disclosed positive correlation with body mass index, and waist and hip circumference. Hyaluronic acid serum level was positively and iron concentration was negatively associated with TGF-beta 1 expression in the selected consecutive liver compartments. Conclusions. The immunohistochemical expression of TGF-beta 1 may be complementary to routine methods of liver fibrosis evaluation.