Digoxin mitigates diethylnitrosamine-induced acute liver injury in mice via limiting production of inflammatory mediators

Single-cell atlas reveals characteristic changes in intrahepatic HBV-specific leukocytes

IMPORTANCE

Hepatitis B virus (HBV)-specific CD8+ T cells play a central role in the clearance of virus and HBV-related liver injury. Acute infection with HBV induces a vigorous, multifunctional CD8+ T cell response, whereas chronic one exhibits a weaker response. Our study elucidated HBV-specific T cell responses in terms of viral abundance rather than the timing of infection. We showed that in the premalignant stage, the degree of impaired T cell function was not synchronized with the viral surface antigen, which was attributed the liver's tolerance to the virus. However, after the development of hepatocellular carcinoma, T cell exhaustion was inevitable, and it was marked by the exhaustion of the signature transcription factor TOX.

Digoxin protects against intervertebral disc degeneration via TNF/NF-κB and LRP4 signaling

Background

Intervertebral disc degeneration (IVDD) is a leading cause of low back pain (LBP). The pathological process of IVDD is associated with inflammatory reactions and extracellular matrix (ECM) disorders. Digoxin is widely used for treating heart failure, and it has been reported to have anti-inflammatory effects.

Objective

This study is to investigate the role of digoxin in the pathogenesis of intervertebral disc degeneration as well as the involved molecular mechanism, particularly the potential target protein.

Methods

We exploited a rat needle model to investigate digoxin's role in intervertebral disc degeneration in vivo. Safranin O staining was used to measure cartilaginous tissue in the intervertebral disc. The morphological changes of intervertebral discs in animal models were determined by Hematoxylin-Eosin (H&E) staining and the pathological score. Primary nucleus pulposus cells (NP cells) from intervertebral discs of patients and murine were used in the present study. Western-Blotting assay, Real-time PCR assay, immunofluorescence staining, and immunochemistry were used to detect the role of digoxin in anti-TNF-α-induced inflammatory effects in vitro. Transfection of siRNA was used to regulate low-density lipoprotein receptor-related protein 4 (LRP4) expression in NP cells to investigate the potential protein target of digoxin.

Results

Digoxin protected against intervertebral disc degeneration in rat needle models. Digoxin was found to exert its disc-protective effects through at least three different pathways by a) suppressing TNF-α-induced inflammation, b) attenuating ECM destruction, c) significantly promoting ECM anabolism. Additionally, LRP4 was found to be the downstream molecule of digoxin in NP cells for anti-inflammation and regulation of ECM metabolism. The knockdown of LRP4 downregulated the protective effect of digoxin in NP cells.

Conclusion

These findings suggest that digoxin may be a potential therapeutic agent for intervertebral disc degeneration through anti-catabolism and pro-anabolism. Digoxin might also work as an alternative for other inflammation-related diseases.

iNKT17 cells play a pathogenic role in ethinylestradiol-induced cholestatic hepatotoxicity

IL-17 is closely associated with inflammation in intrahepatic cholestasis (IHC). Targeting IL-17 ameliorates IHC in mice. Invariant natural killer T (iNKT) cells are predominantly enriched in the liver and they mediate drug-induced liver injury through their secreted cytokines. However, whether iNKT17 cells are involved in ethinylestradiol (EE)-induced IHC remains unclear. In the present study, the administration of EE (10 mg/kg in vivo and 6.25 μM in vitro) promoted the activation and expansion of iNKT17 cells, which contributed to a novel hepatic iNKT17/Treg imbalance. iNKT cell-deficient Jα18^-/- mice and the RORγt inhibitor digoxin (20 μg) alleviated EE-induced cholestatic hepatotoxicity and downregulated the IL-17 signalling pathway. In contrast, the co-administration of EE with recombinant IL-17 (1 μg) to Jα18^-/- mice induced cholestatic hepatotoxicity and increased the infiltration of hepatic neutrophils and monocytes. Importantly, the administration of IL-17^-/- iNKT cells (3.5 × 10⁵) to Jα18^-/- mice resulted in the attenuation of hepatotoxicity and the recruitment of fewer hepatic neutrophils and monocytes than the adoptive transfer of wild-type iNKT cells. These results indicated that iNKT17 cells could exert pathogenic effects. The recruitment and activation of iNKT17 cells could be attributed to the high level of CXCR3 expression on their surface. CXCL10 deficiency ameliorated EE-induced cholestatic liver damage, reduced hepatic CXCR3⁺ iNKT cells and inhibited RORγt expression. These findings suggest that iNKT17 cells play a key role in EE-induced cholestatic liver injury via CXCR3-mediated recruitment and activation. Our study provides new insights and therapeutic targets for cholestatic diseases.