To investigate the expression and clinical significance of Sirt1 and sterol-regulatory element binding proteins (SREBP) in hepatitis C patients with different degrees of fatty liver.

From July 2015 to June 2017, a total of 140 patients with hepatitis C were enrolled in the Department of Hepatology, the First People’s Hospital of Huzhou City, including 80 patients with hepatitis C (20 patients with simple hepatitis C without fatty liver, 20 patients with HCV infected and mild fatty liver, 20 patients with HCV infected and moderate fatty liver and 20 patients with HCV infected and severe fatty liver). There were 60 cases of fatty liver without HCV infection (20 cases of mild fatty liver, 20 cases of moderate fatty liver and 20 cases of severe fatty liver). While 20 healthy people were selected as the normal control group. The sex, age and HCV RNA load (All the patients with hepatitis C were with positive anti-HCV) of the patients were detected, respectively. The peripheral blood samples were collected and the expression of Sirt1 and SREBP were detected by real-time PCR and Western blot.

The levels of Sirt1 in patients with moderate and severe fatty liver were significantly lower than those in patients with hepatitis C: the levels of mRNA decreased by 0.724 times (t = 4.265, P < 0.001) and 0.540 times (t = 2.489, P = 0.013), respectively. The protein levels decreased by 0.69 times (t = 4.857, P < 0.001) and 0.51 times (t = 10.523, P = 0.002), respectively. There was no significant differences of Sirt1 expression between patients with mild fatty liver and HCV infected patients without mild fatty liver (t = 0.344、P = 0.732). The levels of SREBP-1c in HCV infected patients with mild, moderate and severe liver steatosis were higher than those in HCV infected patients without liver steatosis: the level of mRNA increased by 1.132 times (t = -3.924, P < 0.001), 1.424 times (t =-4.300, P < 0.001), and 1.663 times (t =-3.758, P = 0.001), respectively. Protein levels increased by 1.49 times (t =-9.323, P < 0.001) and 1.65 times (t =-14.992, P < 0.001) and 1.79 times (t =-15.847, P < 0.001), respectively, with significant differences. There was no significant difference in SREBP-2 expression among HCV infected patients with mild, moderate and severe liver steatosis and HCV infected patients without liver steatosis (all P > 0.05). In moderate and severe liver steatosis patients, compared with those without HCV infection, the expression of Sirt1 in patients with HCV infection decreased significantly: the level of mRNA decreased by 0.682 times (t = 2.987, P = 0.010) and 0.521 times (t = 5.366, P < 0.001), respectively. The protein levels decreased by 0.800 times (t = 2.801, P = 0.016) and 0.635 times (t = 7.891, P < 0.001), respectively, with significant differences. There was no significant difference of Sirt1 expression between mild fatty liver patients with HCV infection and those without HCV infection (t = 0.344, P = 0.732). In patients with mild, moderate and severe fatty liver, the expression of SREBP-1c in patients with HCV infection was significantly higher than that in patients without HCV infection. The level of mRNA increased by 1.428 times (t =-15.943, P < 0.001), 1.592 times (t =-9.135, P = 0.004) and 1.521 times (t =-9.138, P < 0.001), respectively. Protein levels increased by 1.622 times (t =-7.960, P = 0.010, 1.749 times (t =-2.196, P = 0.012) and 1.803 times (t =-8.942, P = 0.045), respectively, all with significant differences.

Hepatitis C virus infection could affect fatty liver by inhibiting Sirt1 expression and upregulating SREBP-1c expression.