HBsAg-induced ROS drives NK cell exhaustion via LAG-3 upregulation and hinders HBeAg seroconversion in CHB

Dysfunction of NK cells contributes to immune escape in chronic hepatitis B (CHB), yet the regulatory mechanisms, particularly the interplay between immune checkpoints and oxidative stress, remain incompletely understood. This study analyzed 42 CHB patients and 22 healthy controls, revealing a specific elevation in reactive oxygen species (ROS) levels within peripheral blood NK cells from CHB patients. These elevated ROS levels correlated positively with serum HBsAg, HBeAg, HBV-DNA loads, and ALT levels. Further transcriptomic and flow cytometric analyses demonstrated significant upregulation of the immune checkpoint molecule LAG-3 on NK cells from CHB patients, with the LAG-3⁺ NK subset exhibiting higher ROS levels. Mechanistically, in vitro experiments confirmed that HBsAg directly induced ROS burst and upregulated LAG-3 expression in NK cells, a process reversible by the antioxidant N-acetylcysteine. Clinical correlation analysis indicated that NK cell ROS levels predicted HBeAg seroconversion, with a significantly higher success rate in the low-ROS group. Our findings unveil a critical "HBsAg–ROS–LAG-3" axis in CHB immune evasion, providing a novel perspective for combined therapeutic strategies targeting both metabolism and immune checkpoints.