The protective effect of the vagus nerve-α7nAChR-IL-22 pathway on acute liver injury.

Abstract

Background: Acute liver injury is a common pathological feature of various clinical diseases, and prolonged liver damage can lead to fibrosis and even liver failure. Studies have reported that the vagus nerve can repair liver injury through the regulation of the cholinergic anti-inflammatory pathway. However, there is limited research on the regulation of interleukin-22 and its role in liver injury. This study aimed to investigate the regulatory effect of vagus nerve receptor α7nAChR on interleukin-22 and whether this regulatory axis can protect against liver injury.

Methods: Rats and the human liver cell line L-02 were treated with carbon tetrachloride to simulate acute liver injury. The experimental groups were divided as follows: control group, model group, model + PNU282987 group, model + MLA group, and MLA group. After the intervention, blood samples, liver tissues, and cells were collected to assess liver function (AST, ALT), inflammation (TNF-α, IL-6,), α7nAChR and interleukin-22 concentrations, apoptosis levels (Bax, BCL-2), and proliferation markers (Ki-67, PCNA) using quantitative real time PCR, Western blot, immunohistochemistry and ELISA.

Results: The results indicated that carbon tetrachloride intervention led to compensatory increases in interleukin-22 while inhibition of α7nAChR decreased interleukin-22 concentrations and exacerbated the injury marked by high levels of AST, ALT and TNF-α,IL-6. Exogenous administration of a vagus nerve agonist alleviated liver injury and was accompanied by an increase in interleukin-22 levels. In rescue experiments, simultaneous inhibition of vagus nerve receptors and administration of exogenous interleukin-22 reduced liver injury and significantly enhanced liver regeneration. Conversely, activation of vagus nerve receptors while inhibiting interleukin-22 aggravated liver injury.

Conclusion: This study confirms that vagus nerve receptor α7nAChR can promote liver regeneration and protect against carbon tetrachloride-induced liver injury by regulating interleukin-22.