Abstract
Chronic hepatitis B (CHB) has been reported to be associated with impaired prognosis for patients with nasopharyngeal carcinoma (NPC). However, the latent mechanism is unclear. Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) induce immune suppression in CHB and promote the development of hepatocellular carcinoma. Lectin-type oxidized LDL receptor-1 (LOX-1) was recently identified as a specific marker for PMN-MSDC. We found NPC survivors with CHB had high levels of LOX-1(+) PMN-MDSCs. LOX-1(+) PMN-MDSCs significantly reduced T cell proliferation and activation. Endoplasmic reticulum stress was induced in LOX-1(+) PMN-MDSCs. In addition, LOX-1(+) PMN-MDSCs increased their expression of NOX2, a key reactive oxygen species (ROS)-related genes, and levels of ROS illustrated by the DCFDA test. The ROS inhibitor N-acetylcysteine abrogated the suppression of LOX-1(+) PMN-MDSCs on T cell activation. The EBV DNA-positivity rate was higher in NPC survivors with CHB than in NPC patients without CHB. Those presenting with positive EBV DNA displayed higher LOX-1(+) PMN-MDSC levels. LOX-1(+) PMN-MDSCs suppressed the CD8(+) T cell response against EBV. This study revealed LOX-1(+) PMN-MDSC accumulation and activation in NPC survivors with CHB. LOX-1(+) PMN-MDSCs might suppress the host immune response to EBV through ER stress/ROS pathway. These results explained the association of CHB with unfavorable NPC prognosis.