Expression of TNF-alpha and immunohistochemical distribution of hepatic macrophage surface markers in carbon tetrachloride-induced chronic liver injury in rats

In liver injury induced by carbon tetrachloride, secondary hepatic injury occurs from inflammatory processes originating from products released by activated Kupffer cells, which play a central role in hepatic inflammation. The purpose of our study was to demonstrate, in rats, the relationships between a function of the hepatic macrophages, TNF-alpha production and the state of activation of these cells, characterized by their phenotype, in the different phases of the process and development of fibrosis in a carbon tetrachloride-induced cirrhosis model. The immunohistochemical localization of proinflammatory cytokine TNF-alpha and surface surface makers (ED1 and ED2) was studied in hepatitis and cirrhosis in response to 3 and 9 weeks ingestion of carbon tetrachloride. After carbon tetrachloride ingestion, accompanying the increased necrosis, immunohistochemical analysis of liver tissue sections demonstrated the significantly increased number of cells expressing ED1, ED2 and TNF-alpha, compared to normal. The number of cells expressing the surface phenotypic markers of liver macrophages increased and this change was concomitantly associated with an increased cellular expression of TNF-alpha. Local macrophage proliferation and influx of newly recruited blood monocytes resulted in an increase of the macrophage population. The populational changes involved difference in functional activity and enhances TNF-alpha expression. This cytokine expressed in the carbon tetrachloride-induced inflammatory process is associated with the development of fibrosis and may contribute to disease severity.