OBJECTIVETo study the experimental efficacy of Qushi Huayu Decoction (祛湿化瘀方,QHD) on, protein and gene expression of cathepsin B (ctsb) in HepG2 cells induced by free fatty acids (FFAs).

METHODSThe model of HepG2 steatosis and tumor necrosis factor-α (TNF-α) secretion was induced by long-chain FFAs. HepG2 cells were divided into 4 groups: control group (group C), model group (group M), low-dose QHD group (group L) and high-dose QHD group (group H). Long-chain FFAs were added to groups M, L and H. The 10% blank-control serum was added to group C and M, while 5% and 10% QHD-containing sera were added to group L and H, respectively. The levels of serum TNF-α and cellular triglyceride (TG) were detected. Cellular p-IκB and ctsb expression were detected using Western blot and PCR. The expression and distribution of ctsb were observed by immunofluorescence.

RESULTSAfter incubating with FFA for 24 h, TG deposition in HepG2, TNF-α content in cell supernatant, the protein expression of cellular ctsb and P-IκB, as well as mRNA expression of ctsb increased markedly in group M compared with group C (P<0.05, P<0.01). Compared with group M, TG deposition, the expression of cellular ctsb, P-IκB and ctsb mRNA in groups L and H, as well as TNF-α content in group H, decreased significantly (P<0.05). Cell immunochemical fluorescence studies showed that ctsb was released from lysosomes and distributed in the cytoplasm extensively and diffusedly after being stimulated with FFA. In this study, these above-mentioned changes were inhibited markedly in groups L and H.

CONCLUSIONQHD might have a direct inhibitory effect on the ctsb target in the FFA-ctsb-TNFα pathway of hepatic lipotoxicity.