Down-regulation of cell membrane localized NTCP expression in proliferating hepatocytes prevents hepatitis B virus infection

Abstract

Hepatocyte proliferation could result in the loss of covalently closed circular DNA (cccDNA) and the emergence of cccDNA-cleared nascent hepatocytes, which appear refractory to hepatitis B virus (HBV) reinfection with unknown mechanism(s). Sodium taurocholate cotransporting polypeptide (NTCP) is the functional receptor for HBV entry. In this study, down-regulation of cell membrane localized NTCP expression in proliferating hepatocytes was found to prevent HBV infection in HepG2-NTCP-tet cells and in liver-humanized mice. In patients, lower NTCP protein expression was correlated well with higher levels of hepatocyte proliferation and less HBsAg expression in HBV-related focal nodular hyperplasia (FNH) tissues. Clinically, significantly lower NTCP protein expression was correlated with more active hepatocyte proliferation in CHB patients with severe active necroinflammation and better antiviral treatment outcome. Mechanistically, the activation of cell cycle regulatory genes p53, S-phase kinase-associated protein 2 (SKP2) and cyclin D1 during cell proliferation, as well as proliferative and inflammatory cytokine Interleukin-6 (IL-6) could transcriptionally down-regulate NTCP expression. From these aspects, we conclude that within the milieu of hepatocyte proliferation, down-regulation of cell membrane localized NTCP expression level renders nascent hepatocytes resistant to HBV reinfection. This may accelerate virus clearance during immune-mediated cell death and compensatory proliferation of survival hepatocytes.

The molecular mechanism of TiaoGanYiPi formula for treatment of chronic hepatitis B by network pharmacology and molecular docking verification

“…Speci cally, among the 11 key target genes, CCNB1, CDKN1A, EP300, ABL1, CDK4, and CCNA2 are enriched in the cell cycle pathway, and previous studies have shown that the expression of these factors could regulate the cell cycle to varying degrees, promote or inhibit cell proliferation [21][22][23][24][25][26] . Hepatocyte proliferation has been reported to accelerate during HBV infection 27 , leading to the downregulation of NTCP in hepatocytes, which contributes to HBV cccDNA loss and further accelerates HBV clearance 12,28 . Our study suggested that TGYP might exert anti-HBV effects by regulating the cell-cycle-related genes which manipulate hepatocyte proliferation.…”

“…Results suggested the expression of these key genes were possibly related to the disease status of CHB. Furthermore, CHB patients with signi cant liver in ammation could bene t from improved antiviral effect 12 . To further explore the relationship between key target genes and liver in ammation in CHB patients, we compared the expression of 71 patients with abnormal serum ALT or AST levels (ALT ≥ 40 or AST ≥ 35) and 34 patients with normal serum ALT and AST levels (ALT < 40 and AST < 35).…”

Innovative HBV Animal Models Based on the Entry Receptor NTCP

“…NTCP has a very short half-life of less than 24 h and its expression is rapidly downregulated in isolated primary hepatocytes in vitro [42,43]. This down-regulation is responsible for reduced or blocked HBV infection in long-term cultured primary human hepatocytes and most immortalized human hepatoma cell lines [44]. Therefore, overexpressing human NTCP on these cells is necessary to study HBV infection in vitro [45].…”

Decrease of Clone Diversity in IgM Repertoires of HBV Chronically Infected Individuals With High Level of Viral Replication

“…Notably, the discovery of the sodium taurocholate co-transporting polypeptide (NTCP) as the receptor of HBV has largely advanced our understanding of humoral immune responses and anti-HBV antibodies during chronic HBV infection, which was largely neglected in previous HBV studies ( Yan et al, 2012 ; Ni et al, 2014 ). The NTCP interacts directly with the preS1 domain of the HBV surface antigen (HBsAg), and antibodies against HBsAg could block the virus entry into cells, neutralize the virus, and restrict the spread of HBV ( Wu et al, 2019 ; Yan et al, 2019 ). Thus, antibodies play important roles in limiting HBV infections and eliminating the virus.…”