Hypoxia inducible factor 1α promotes interleukin-1 receptor antagonist expression during hepatic ischemia-reperfusion injury

BACKGROUND Ischemia-reperfusion injury (IRI) is a major risk associated with liver surgery and transplantation, and its pathological mechanism is complex. Interleukin-1 receptor antagonist (IL-1ra) can protect the liver from IRI. However, the regulatory mechanism of IL-1ra expression is still unclear. AIM To identify the mechanism that could protect the liver in the early stage of IRI. METHODS To screen the key genes in hepatic IRI, we performed RNA sequencing and gene enrichment analysis on liver tissue from mice with hepatic IRI. Subsequently, we verified the expression and effect of IL-1ra in hepatic IRI. We also used promoter mutagenesis and chromatin immunoprecipitation assay to search for the transcriptional regulatory sites of hypoxia-inducible factor (HIF)-1 alpha. Finally, to explore the protective mechanism of ischemic preconditioning (IP), we examined the expression of HIF-1 alpha and IL-1ra after IP. RESULTS We identified IL-1ra as a key regulator in hepatic IRI. The expression of IL-1ra was significantly upregulated after hepatic IRI both in vivo and in vitro. Furthermore, we found that HIF-1 alpha regulated Il-1ra transcription in response to hypoxia. Increased HIF-1 alpha accumulation promoted IL-1ra expression, whereas inhibition of HIF-1 alpha exhibited the opposite effect. We also confirmed a predominant role for hypoxia response element in the regulation of Il1ra transcription by HIF-1 alpha activation. Of note, we demonstrated that IP protects against hepatic IRI by inducing IL-1ra expression, which is mediated through HIF-1 alpha. CONCLUSION We demonstrated that ischemia or hypoxia leads to increased expression of IL-1ra through HIF-1 alpha. Importantly, IP protects the liver from IRI via the HIF-1 alpha-IL-1ra pathway.