Pathogen DNA also contributes to interferon regulatory factor 3 activation in hepatic cells: Implications for alcoholic liver diseases

Hepatocyte GPCR signaling regulates IRF3 to control hepatic stellate cell transdifferentiation

BACKGROUND

Interferon Regulatory Factor 3 (IRF3) is a transcription factor that plays a crucial role in the innate immune response by recognizing and responding to foreign antigens. Recently, its roles in sterile conditions are being studied, as in metabolic and fibrotic diseases. However, the search on the upstream regulator for efficient pharmacological targeting is yet to be fully explored. Here, we show that G protein-coupled receptors (GPCRs) can regulate IRF3 phosphorylation through of GPCR-Gα protein interaction.

RESULTS

IRF3 and target genes were strongly associated with fibrosis markers in liver fibrosis patients and models. Conditioned media from MIHA hepatocytes overexpressing IRF3 induced fibrogenic activation of LX-2 hepatic stellate cells (HSCs). In an overexpression library screening using active mutant Gα subunits and Phos-tag immunoblotting, Gαs was found out to strongly phosphorylate IRF3. Stimulation of Gαs by glucagon or epinephrine or by Gαs-specific designed GPCR phosphorylated IRF3. Protein kinase A (PKA) signaling was primarily responsible for IRF3 phosphorylation and Interleukin 33 (IL-33) expression downstream of Gαs. PKA phosphorylated IRF3 on a previously unrecognized residue and did not require reported upstream kinases such as TANK-binding kinase 1 (TBK1). Activation of Gαs signaling by glucagon induced IL-33 production in hepatocytes. Conditioned media from the hepatocytes activated HSCs, as indicated by α-SMA and COL1A1 expression, and this was reversed by pre-treatment of the media with IL-33 neutralizing antibody.

CONCLUSIONS

Gαs-coupled GPCR signaling increases IRF3 phosphorylation through cAMP-mediated activation of PKA. This leads to an increase of IL-33 expression, which further contributes to HSC activation. Our findings that hepatocyte GPCR signaling regulates IRF3 to control hepatic stellate cell transdifferentiation provides an insight for understanding the complex intercellular communication during liver fibrosis progression and suggests therapeutic opportunities for the disease. Video Abstract.

Single-incision laparoscopic surgery to treat hepatopancreatobiliary cancer: A technical review

Single-incision laparoscopic surgery (SILS), or laparoendoscopic single-site surgery, was launched to minimize incisional traumatic effects in the 1990s. Minor SILS, such as cholecystectomies, have been gaining in popularity over the past few decades. Its application in complicated hepatopancreatobiliary (HPB) surgeries, however, has made slow progress due to instrumental and technical limitations, costs, and safety concerns. While minimally invasive abdominal surgery is pushing the boundaries, advanced laparoscopic HPB surgeries have been shown to be comparable to open operations in terms of patient and oncologic safety, including hepatectomies, distal pancreatectomies (DP), and pancreaticoduodenectomies (PD). In contrast, advanced SILS for HPB malignancy has only been reported in a few small case series. Most of the procedures involved minor liver resections and DP; major hepatectomies were rarely described. Single-incision laparoscopic PD has not yet been reported. We herein review the published SILS for HPB cancer in the literature and our three-year experience focusing on the technical aspects.

The Cytosolic DNA-Sensing cGAS-STING Pathway in Liver Diseases

Inflammation is regulated by the host and is a protective response activated by the evolutionarily conserved immune system in response to harmful stimuli, such as dead cells or pathogens. cGAS-STING pathway is a vital natural sensor of host immunity that can defend various tissues and organs against pathogenic infection, metabolic syndrome, cellular stress and cancer metastasis. The potential impact of cGAS-STING pathway in hepatic ischemia reperfusion (I/R) injury, alcoholic/non-alcoholic steatohepatitis (ASH), hepatic B virus infection, and other liver diseases has recently attracted widespread attention. In this review, the relationship between cGAS-STING pathway and the pathophysiological mechanisms and progression of liver diseases is summarized. Additionally, we discuss various pharmacological agonists and antagonists of cGAS-STING signaling as novel therapeutics for the treatment of liver diseases. A detailed understanding of mechanisms and biology of this pathway will lay a foundation for the development and clinical application of therapies for related liver diseases.