Hepatic mast cell concentration directly correlates to stage of fibrosis in NASH

Mast cells are present throughout the body in low numbers. We know their role in immediate hypersensitivity and the subsequent tissue damage due to release of cytokines, vasoactive amines, and lipid mediators when mast cells are activated. Recent research has found that there is an association between an increased concentration of mast cells in the liver and the severity of hepatic fibrosis in animal models. We currently don't understand the role of mast cells in the liver with regard to fibrosis. This retrospective review study investigated whether there is a correlation between stages of fibrosis and mast cell concentrations. One hundred six tissue slides were collected from a large military hospital of known cases of unremarkable liver, non-alcoholic fatty liver disease (Non-NASH NAFLD), and each stage of NASH (Non-alcoholic steatohepatitis). These were analyzed by staining the slides with tryptase to highlight and quantify the mast cell concentration in each diagnostic category. Three pathologists counted mast cells in five 400× fields (1 square mm) in both the periportal and parenchymal regions of each slide. These numbers were recorded and analyzed with a t test, demonstrating an increase in mast cells in NASH stage 3-4 fibrosis compared to unremarkable liver (35.48 versus 18.23, respectively, P < .001) and a direct correlation (r = 0.287) between the number of mast cells and the stage of fibrosis. Better characterizing the role of mast cells in the development of hepatic fibrosis gives us a greater understanding of the pathophysiology of non-NASH NAFLD and NASH and possibly a pharmaceutical target.