Aim: To investigate the innate immune reactivity of tumor necrosis factor-alpha (TNF-alpha), Toll-like receptor 4 (TLR4), and CD14 in the liver of non-alcoholic steatohepatitis (NASH) model rats.
Methods: Male F344 rats were fed a choline-deficient L-amino-acid-defined (CDAA) diet. The rats were killed after 4 or 8 wk of the diet, and their livers were removed for immunohistochemical investigation and RNA extraction. The liver specimens were immunostained for TNF-alpha, TLR4, and CD14. The gene expressions of TNF-alpha, TLR4, and CD14 were determined by reverse-transcriptase polymerase chain reaction (RT-PCR). Kupffer cells were isolated from the liver by Percoll gradient centrifugation, and were then cultured to measure TNF-alpha production.
Results: The serum and liver levels of TNF-alpha in the CDAA-fed rats increased significantly as compared with the control group, as did the immunohistochemical values and gene expressions of TNF-alpha, TLR4, and CD14 with the progression of steatohepatitis. TNF-alpha production from the isolated Kupffer cells of the CDAA-fed rats was elevated by lipopolysaccharide stimulation.
Conclusion: The expressions of TNF-alpha, TLR4, and CD14 increased in the NASH model, suggesting that TLR4 and CD14-mediated endotoxin liver damage may also occur in NASH.