Abstract: Objective To study on the association of microRNA-122 (mir-122) and microRNA-146a (mir-146a) levels in serum exosomes of chronic hepatitis B (CHB) patients with hepatitis B viral DNA (HBV DNA) load. Methods 285 CHB patients were divided into low viral load group (HBV DNA < 1 ×10⁵ copy/ml), medium viral load group (1 ×10⁵ copy/ml ≤ HBV DNA ≤ 1 ×10⁷ copy/ml) and high viral load group (HBV DNA > 1 ×10⁷ copy/ml) with 95 cases in each group. Serum HBV DNA was detected by fluorescence real time quantitative PCR (RT-qPCR). In addition, serum samples from 95 healthy outpatients were collected simultaneously as the control group. The levels of mir-122 and mir-146a in serum exosomes were detected by RT-qPCR; Serum indexes of liver fibrosis were measured by chemiluminescence method. Pearson correlation analysis was applied for analyzing the association between serum exosome levels of mir-122 and mir-146a with HBV DNA load, and liver fibrosis indexes. Results Compared with the control group, the HBV DNA load, mir-122 level in serum exosomes, and the levels of serum hepatic fibrosis indexes including Hyaluronidase (HA), procollagen Ⅲ (PC Ⅲ), collagen Ⅳ(C Ⅳ) and laminin (LN) in low, medium and high HBV DNA load groups increased, whereas the level of mir-146a decreased in turn (P<0.05). The levels of mir-122 and mir-146a in serum exosome were found negatively correlated with HBV DNA load (r=0.765, P<0.05). The level of mir-122 was positively correlated with HBV DNA load and serum HA, PC Ⅲ, C Ⅳ and LN levels (r= 0.773, 0.764, 0.699, 0.665, 0.697, respectively, P<0.05), whereas the level of mir-146a was negatively correlated with these parameters (r=-0.840, -0.779, -0.731, -0.691, -0.738, respectively, P<0.05). Conclusion The expression and secretion of Mir-122 in serum exosome of CHB patients is up-regulated and that of mir-146a is down-regulated. They are closely co-related with HBV DNA load and may impact on HBV DNA replication, the severity of hepatic fibrosis, and the progression of CHB.

Key words: Chronic hepatitis B, microRNA-122, microRNA-146a, Hepatitis B virus, Exosome