Neutrophils, an important component of the innate immune system, release extracellular traps (NETs) to eliminate invading pathogens by trapping and killing microbes. Recent studies have shown that NETs play a multitude of additional roles in immunity and inflammatory diseases. Therefore, NETs may be involved in persistent hepatitis B virus (HBV) infection, and the objectives of the current study were to determine whether HBV influences NET release and to identify the underlying mechanisms. HBV-infected mice (C57BL/6) were used to detect the efficiency of bacterial eradication by neutrophils in vivo. Primary neutrophils and circulating blood samples were collected from 40 patients with chronic hepatitis B infection, as well as 40 healthy controls, to detect NET release using a Quant-iT Pico Green dsDNA assay, Western blotting, and live-cell imaging and to determine the levels of HBV-DNA and HBV markers. NET release was decreased in patients with chronic hepatitis B infection, and hepatitis B surface Ag, hepatitis B E Ag, and hepatitis B core Ab levels negatively correlated with NET release. We also examined the effect of HBV proteins (HBV X protein, HBV C protein, HBV E protein, and HBV S protein) on NET release in vitro. Based on flow cytometry, cytochrome c reduction assay, and Western blotting, HBV C protein and HBV E protein inhibited NET release by decreasing reactive oxygen species production and autophagy. Overall, HBV may inhibit NET release by modulating reactive oxygen species production and autophagy to escape the immune system and promote the establishment of chronic infection.
Copyright © 2019 by The American Association of Immunologists, Inc.