Expression and role of interleukin 35-producing B cells and interleukin 35 from peripheral blood of patients with chronic hepatitis B

Abstract

Objective To explore the level of interleukin 35-producing B cells (i35-Breg) as well as its effect factors, interleukin-35 (IL-35), in peripheral blood of patients with chronic hepatitis B (CHB), and their relationship with hepatitis B virus(HBV) DNA and liver inflammatory degree. Methods A total of 35 treatment-naive CHB patients, 17 interferon (IFN)-treated HBeAg-positive CHB patients and 15 healthy controls (HC) were enrolled. The levels of i35-Breg and IL-35 in peripheral blood were tested by flow cytometry and enzyme-linked immunosorption assay (ELISA). Kruskal-Wallis test, Wilcox rank sum test and two variables correlation analysis were used for statistical analysis. Results The percentage of i35-Breg cells as well as IL-35 level in peripheral blood of naive CHB patients were 3.05% (0.89%, 4.97%) and 2.81 μg/L (0.30 μg/L, 12.33 μg/L), respectively, which were both significantly higher than those in HC group, which were 0.17% (0.13%, 0.45%) and 0.17 μg/L(0, 1.93 μg/L), respectively. The difference were statistical significant (Z=-3.309 and -2.419, respectively, P=0.001 and 0.016, respectively). The peripheral level of i35-Breg was negatively correlated with the viral load in treatment-naive CHB patients (r=-0.529, P=0.008), while there was no correlation between the peripheral level of IL-35 and the viral load in treatment-naive CHB patients (r=0.11, P=0.54). The levels of i35-Breg and IL-35 in HBeAg positive CHB patients were 3.16% (1.34%, 5.62%) and 4.58 μg/L (0.79 μg/L, 22.37 μg/L), respectively, which were both higher than those in HC group. The difference was statistically significant (F=3.39 and 3.37, respectively, both P<0.01). Compared to HC group, the IL-35 levels in peripheral blood of CHB patients with ALT and AST levels less than 300 U/L were 3.03 μg/L (0.74 μg/L, 22.37 μg/L) and 3.25 μg/L(0.83 μg/L, 22.35 μg/L), respectively, with statistically significant difference (F=2.868 and 3.114, respectively, both P<0.01). Compared to HC group, the peripheral level of i35-Breg in treatment-naive CHB patients with ALT levels less than 300 U/L was 3.14% (1.03%, 4.65%), with statistically significant difference (F=3.219, P=0.004). The IL-35 level showed a decreased trend in CHB who received IFN therapy, but there was no statistically significant difference (χ2=1.45, P=0.48). Furthermore, the baseline IL-35 level in patients who developed sustained viral response (SVR) was 0 (0, 13.33 g/L), which was lower than that in patients who developed partial or primary no response 0.61 μg/L (0, 24.72 μg/L). However, there was no statistical difference (F=0.75, P=0.68). Conclusions i35-Breg as well as its effect factor, IL-35, are involved in the progression of chronic HBV infection. The percentage of i35-Breg cells as well as IL-35 level in peripheral blood of treatment-naive CHB patients are increased. The peripheral level of i35-Breg is negatively correlated with the viral load, while there is no correlation between the peripheral level of IL-35 and the viral load. The percentage of i35-Breg cells as well as IL-35 level in CHB patients with low inflammatory degree are increased. Key words: Hepatitis B, chronic; Interleukin-35; IL-35-producing B cells