Non-selective dampening of the host immune response after hepatitis C clearance and its association with circulating chemokine and endotoxin levels.

BACKGROUND & AIMS: Direct-acting antiviral (DAA) therapy has revolutionized treatment for the hepatitis C virus (HCV). While DAA therapy is common, little is known about the intrahepatic immunological changes after sustained virologic response (SVR). We aim to describe transcriptional alterations of the gut microbiome and the liver after SVR. METHODS: Twenty-two HCV patients were evaluated before and 9 months after 12 weeks of sofosbuvir/velpatasvir treatment. All achieved SVR. A liver biopsy, portal blood (direct portal vein cannulation), peripheral blood and stool samples were obtained. RNA-seq and immunofluorescent staining were performed on liver biopsies. RNA-seq and 16S rRNA metagenomics were performed on stool. RESULTS: Differential expression within liver transcription showed 514 downregulated genes (FDR q < .05; foldchange > 2) enriched in inflammatory pathways; of note, GO:0060337, type 1 IFN signalling (p = 8e-23) and GO:0042742, defence response to bacterium (p = 8e-3). Interestingly, microbial products increased in the portal blood and liver after SVR. Due to the increase in microbial products, the gut microbiome was investigated. There was no dysbiosis by Shannon diversity index or Bacteroides/Firmicutes ratio. There was a differential increase in genes responsible for bacterial lipopolysaccharide production after SVR. CONCLUSIONS: The decrease in the antiviral interferon pathway expression was expected after SVR; however, there was an unanticipated decrease in the transcription of genes involved in recognition and response to bacteria, which was associated with increased levels of microbial products. Finally, the alterations in the function of the gut microbiome are a promising avenue for further investigation of the gut-liver axis, especially in the context of the significant immunological changes noted after SVR.

Inflammatory pathways in alcoholic steatohepatitis.

Inflammatory processes are primary contributors to the development and progression of alcoholic steatohepatitis (ASH), with severe alcoholic hepatitis characterised by non-resolving inflammation. Inflammation in the progression of ASH is a complex response to microbial dysbiosis, loss of barrier integrity in the intestine, hepatocellular stress and death, as well as inter-organ crosstalk. Herein, we review the roles of multiple cell types that are involved in inflammation in ASH, including resident macrophages and infiltrating monocytes, as well as other cell types in the innate and adaptive immune system. In response to chronic, heavy alcohol exposure, hepatocytes themselves also contribute to the inflammatory process; hepatocytes express a large number of chemokines and inflammatory mediators and can also release damage-associated molecular patterns during injury and death. These cellular responses are mediated and accompanied by changes in the expression of pro- and anti-inflammatory cytokines and chemokines, as well as by signals which orchestrate the recruitment of immune cells and activation of the inflammatory process. Additional mechanisms for cell-cell and inter-organ communication in ASH are also reviewed, including the roles of extracellular vesicles and microRNAs, as well as inter-organ crosstalk. We highlight the concept that inflammation also plays an important role in promoting liver repair and controlling bacterial infection. Understanding the complex regulatory processes that are disrupted during the progression of ASH will likely lead to better targeted strategies for therapeutic interventions.

Perivascular Adipocytes Store Norepinephrine by Vesicular Transport.

Objective- Perivascular adipose tissue (PVAT) contains an independent adrenergic system that can take up, metabolize, release, and potentially synthesize the vasoactive catecholamine norepinephrine. Norepinephrine has been detected in PVAT, but the mechanism of its protection within this tissue is unknown. Here, we investigate whether PVAT adipocytes can store norepinephrine using VMAT (vesicular monoamine transporter). Approach and Results- High-performance liquid chromatography identified norepinephrine in normal male Sprague Dawley rat aortic, superior mesenteric artery, and mesenteric resistance vessel PVATs, and retroperitoneal fat. Real-time polymerase chain reaction revealed VMAT1 and VMAT2 mRNA expression in the adipocytes and stromal vascular fraction of mesenteric resistance vessel PVAT. Immunofluorescence demonstrated the presence of VMAT1 and VMAT2, and the colocalization of VMAT2 with norepinephrine, in the cytoplasm of adipocytes in mesenteric resistance vessel PVAT. A protocol was developed to capture real-time uptake of Mini 202-a functional and fluorescent VMAT probe-in live rat PVAT adipocytes. Mini 202 was taken up by freshly isolated and differentiated adipocytes from mesenteric resistance vessel PVAT and adipocytes from thoracic aortic and superior mesenteric artery PVATs. In adipocytes freshly isolated from mesenteric resistance vessel PVAT, addition of rose bengal (VMAT inhibitor), nisoxetine (norepinephrine transporter inhibitor), or corticosterone (organic cation 3 transporter inhibitor) significantly reduced Mini 202 signal. Immunofluorescence supports that neither VMAT1 nor VMAT2 is present in retroperitoneal adipocytes, suggesting that PVAT adipocytes may be unique in storing norepinephrine. Conclusions- This study supports a novel function of PVAT adipocytes in storing amines in a VMAT-dependent manner. It provides a foundation for future studies exploring the purpose and mechanisms of norepinephrine storage by PVAT in normal physiology and obesity-related hypertension.