Hepatitis B virus-induced hyperactivation of B cells in chronic hepatitis B patients via TLR4.

B cell hyperactivation and functional impairment were identified from patients with chronic hepatitis B virus (CHB) infection; however, the underlying mechanism remains unknown. Here, we aim to elucidate the mechanisms responsible for B cell hyperactivation during HBV infection. Peripheral CD19+  B cells isolated from 4 CHB patients and 4 healthy volunteers were analysed by RNA sequencing. A total of 1401 differentially expressed genes were identified from B cell transcriptome of CHB patients vs healthy volunteers. We found that B cells from CHB patients were functional impaired, with increased TLR4 expression, activated NF-κB pathway and altered mitochondrial function. The expression of B cell activation-related genes, including TLR4, was further validated using additional clinical samples. To further verify the role of TLR4 in B cell activation during CHB, B cell phenotypes were determined in wild-type (WT) and TLR4-/- HBV-carrier mice. Hyperactivated B cell and TLR4 signalling pathway were observed in WT HBV-carrier mice, while TLR4 ablation failed to induce B cell hyperactivation, and downstream MyD88 and NF-κB were also not altered. Taken together, TLR4 pathway plays a pivotal role in B cell hyperactivation during CHB, which might serve as a promising target for B cell function restoration.