Relevance of serum interleukin-33 and ST2 levels and the natural course of chronic hepatitis B virus infection

Background: Interleukin-33 (IL-33) and ST2 have been demonstrated to be associated with liver damage. However, their potential value in hepatitis B virus (HBV) infection remains unknown. This study was designed to investigate the change of serum IL-33 and ST2 levels in the natural course of chronic HBV infection. Methods: A total of 120 patients with chronic hepatitis B (CHB), 20 chronic hepatitis B virus carriers in immunotolerant phase and 28 healthy controls were enrolled in this study. All patients with CHB were divided into four groups according to their serum ALT levels. The serum levels of IL-33 and ST2 of all participants were determined by enzyme-linked immunosorbent assay, and compared between each two out of those six groups. Results: No significant differences were found in serum levels of IL-33 and ST2 between the group of CHB with ALT 1-2 upper limit of normal and the healthy controls (P = 0.354 for IL-33 and P = 0.815 for ST2). Other than that, there were significant differences when serum levels of IL-33 and ST2 were compared between any other two out of those six groups (P < 0.05, respectively). The overall correlation analysis indicated that changes of serum IL-33 and ST2 levels were positively associated with ALT levels in patients with chronic HBV infection (rs = 0.879, P < 0.001 for IL-33 and rs = 0.923, P < 0.001 for ST2). No significant differences were found when the serum levels of ALT, IL-33 and ST2 were compared between patients with HBeAg-positive CHB and HBeAg-negative CHB. Conclusions: Our study revealed that the serum levels of IL-33 and ST2 varied in different courses of chronic hepatitis B virus infection. The serum levels of IL-33 and ST2 elevated as serum ALT levels increased in patients with CHB. They might indicate liver damage for patients with CHB, just like ALT.