Extracellular gp96 is a crucial mediator for driving immune hyperactivation and liver damage

Abstract

Liver failure leads to the massive necrosis of hepatocytes, releasing large amounts of intracellular components including damage-associated molecular patterns (DAMPs). We found that extracellular gp96 levels in serum were elevated in patients with chronic hepatitis B infection (CHB) and acuteon-chronic liver failure (ACLF). Meanwhile, the gp96 level positively correlated with hepatic necroinflammation. We employed two mouse liver damage and liver failure models induced by lipopolysaccharide (LPS) plus d-galactosamine (d-Galn), and concanavalin A (ConA) to identify the function of extracellular gp96. As a result, the inhibition of extracellular gp96 by a specific peptide efficiently mitigated both LPS/d-Galn-and ConA-induced liver injury and immune hyperactivation, whereas exogenous gp96 aggravated the symptoms of hepatic injury in mice but not in Kupffer cells-ablated mice. The exposure of Kupffer cells to gp96 induced the secretion of pro-inflammatory cytokines. Collectively, our data demonstrate that gp96 released from necrotic hepatocytes aggravates immune hyperactivation and promotes liver damage and possibly the development of liver failure mainly by activating Kupffer cells.

Plasma gp96 is a Novel Predictive Biomarker for Severe COVID-19

“…Single-cell RNA sequencing of blood antigen-presenting cells in severe COVID-19 reveals that pathways related to NF-κB signaling were upregulated in plasmacytoid dendritic cells and CD14 + monocytes ( 29 ). We and others also show that extracellular gp96 induced proinflammatory cytokines (e.g., IL-6 and TNF-α) in activated immune cells ( 30 – 32 ). Taken together, our study indicates that extracellular gp96 is released from the damaged and necrotic cells after SARS-CoV-2 infection and stimulates monocytes and other proinflammatory immune cells to secrete IL-6 through the NF-KB pathway.…”

“…SARS-CoV-2 infection may lead to an uncontrollable immune response and subsequent sepsis or septic shock through the release of various DAMPs and cytokines ( 33 , 34 ). A number of studies have demonstrated the ability of extracellular gp96 as a DAMP to drive inflammation ( 30 , 31 ). Our study found that levels of plasma gp96 and IL-6 were closely correlated in COVID-19 patients that and gp96 can act as DAMP to activate CD14 + cells to secrete IL-6.…”

“…Plasma gp96 was measured using ELISA, as reported previously ( 30 ). The principle of the assay is agglutination of the carbohydrate antigen in samples with a gp96 monoclonal antibody by antigen-antibody reaction.…”

“…PBMCs were resuspended in RPMI 1640 (GIBCO) medium containing 10% heat-inactivated fetal bovine serum (Gibco), 25 μg/mL streptomycin (Gibco), and 100 IU/mL penicillin (Gibco), and aliquots were at a concentration of 1 × 10 6 cells/mL/well in 6-well or 12-well culture plates (Corning). The cells were exposed to 0 to 50 μg/mL human gp96, and after 12 h or 24 h of culture, the cells and the suspension were harvested for ELISA (IL-6 human ELISA kit; Invitrogen), Western blot, real-time PCR, or flow cytometric analysis as described previously ( 30 , 36 ). Western blotting was performed using mouse anti-GAPDH, rabbit anti-IL-6, goat anti-mouse IgG horseradish peroxidase (HRP), and goat anti-rabbit IgG HRP (Abcam).…”

Cirrhosis-associated immune dysfunction

“…Similar findings have been reported in the context of acute deterioration of liver function in patients with chronic hepatitis B infection 77 . Intracellular components released by necrotic hepatocytes (such as HMGB1, cyclophilin A, gp60) contribute to exacerbating hepatic inflammation in experimental models of liver failure 78,79 . The clinical and experimental evidence supporting the contribution of liver-derived DAMPs to systemic inflammation in alcohol-induced ACLF is weaker than that for the driving-role of gut-derived PAMPs.…”