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Activation of hepatic stellate cells (HSC) is a key event in the initiation of liver fibrosis. Activated HSCs proliferate and secrete excessive amounts of extracellular matrix (ECM), disturbing liver architecture and function, leading to fibrosis and eventually cirrhosis. Collagen is the most abundant constituent of ECM and proline is the most abundant amino acid of collagen. Arginine is the precursor in the biosynthetic pathway of proline. Arginine is the exclusive substrate of both nitric oxide synthase (NOS) and arginase. NOS is an M1 (proinflammatory) marker of macrophage polarization whereas arginase-1 (Arg1) is an M2 (profibrogenic) marker of macrophage polarization. Differential expression of NOS and Arg1 has not been studied in HSCs yet. To identify the expression profile of arginine catabolic enzymes during HSC activation and to investigate their role in HSC activation, primary rat HSCs were cultured-activated for 7 days and expression of iNOS and Arg1 were investigated. Nor-NOHA was used as a specific and reversible arginase inhibitor. During HSC activation, iNOS expression decreased whereas Arg1 expression increased. Inhibition of Arg1 in activated HSCs efficiently inhibited collagen production but not cell proliferation. HSC activation is accompanied by a switch of arginine catabolism from iNOS to Arg1. Inhibition of Arg1 decreases collagen synthesis. Therefore, we conclude that Arg1 can be a therapeutic target for the inhibition of liver fibrogenesis.

Background: Activation of hepatic stellate cells (HSC) leads to initiation and progression of hepatic fibrosis. HSC senescence is inversely correlated with HSC proliferation and activation. Therefore, induction of HSC senescence may be a strategy to treat hepatic fibrosis. Coumarin-derivatives like esculetin have been suggested to inhibit proliferation of fibrogenic cells. Therefore, in this study we aimed to investigate the effect of esculetin on HSC activation and senescence.Methods: Primary rat HSC were used in all experiments. Real-time cell analyzer and BrdU incorporation assay were used to determine HSC proliferation. Gene expression of the senescence-associated genes Cdkn1a (p21), P53, activation markers Acta2, Col1a1 and quiescence markers Pparg and Lrat were measured by RT-qPCR. Senescence associated β-Galactosidase (SA-β-Gal) staining was used to identify senescent HSC.Results: Our results demonstrate that esculetin increased markers of senescence and decreased proliferation and activation markers in HSC. Protein expression of P21Cip1, accompanied by phosphorylation of Ser473 Akt and Ser9 GSK3β was increased by esculetin. The effect of esculetin was dependent on PI3K-Akt signaling.Conclusion: We conclude that esculetin induces HSC senescence and reverses the activated phenotype of HSC. The induction of senescence depends on PI3K-Akt-GSK3β signaling. Esculetin could be a potential therapeutic drug for the treatment of hepatic fibrosis by inducing stellate cell senescence.

Liver fibrosis is a chronic disease associated with oxidative stress that has a great impact on the population mortality. Due to their antioxidant capacity, we evaluated the protective effect of

Simple Summary: Barrett's esophagus (BE) is the precursor of esophageal adenocarcinoma (EAC). Dysplastic BE (DBE), including low-grade dysplasia (LGD) and high-grade dysplasia (HGD), shows a higher progression risk to EAC compared to non-dysplastic BE (NDBE). If LGD or HGD is detected, more intensive endoscopic surveillance or endoscopic treatment is recommended. This results in a significantly improved prognosis compared to EACs treated by surgery and/or chemoradiotherapy. However, the miss rates for detecting DBE by endoscopy remain high. Fluorescence molecular endoscopy (FME) can fill this gap by targeting the tumor-specific expression of proteins. This study aimed to identify target proteins suitable for FME. We identified SPARC, SULF1, PKC iota, and DDR1 as promising imaging targets for FME to differentiate DBE from NDBE tissue. We are also the first to develop near-infrared fluorescent tracers, SULF1-800CW and SPARC-800CW, for the endoscopic imaging of DBE tissue.Abstract: Barrett's esophagus (BE) is the precursor of esophageal adenocarcinoma (EAC). Dysplastic BE (DBE) has a higher progression risk to EAC compared to non-dysplastic BE (NDBE). However, the miss rates for the endoscopic detection of DBE remain high. Fluorescence molecular endoscopy (FME) can detect DBE and mucosal EAC by highlighting the tumor-specific expression of proteins. This study aimed to identify target proteins suitable for FME. Publicly available RNA expression profiles of EAC and NDBE were corrected by functional genomic mRNA (FGmRNA) profiling. Following a class comparison between FGmRNA profiles of EAC and NDBE, predicted, significantly upregulated genes in EAC were prioritized by a literature search. Protein expression of prioritized genes was validated by immunohistochemistry (IHC) on DBE and NDBE tissues. Near-infrared fluorescent tracers targeting the proteins were developed and evaluated ex vivo on fresh human specimens. In total, 1976 overexpressed genes were identified in EAC (n = 64) compared to NDBE (n = 66) at RNA level. Prioritization and IHC validation revealed SPARC, SULF1, PKC iota, and DDR1 (all p < 0.0001) as the most attractive imaging protein targets for DBE detection. Newly developed tracers SULF1-800CW and SPARC-800CW both showed higher fluorescence intensity in DBE tissue compared to paired non-dysplastic tissue. This study identified SPARC, SULF1, PKC iota, and DDR1 as promising targets for FME to differentiate DBE from NDBE tissue, for which SULF1-800CW and SPARC-800CW were successfully ex vivo evaluated. Clinical studies should further validate these findings.

BACKGROUND: The number of patients with non-alcoholic fatty liver disease (NAFLD) is rapidly increasing due to the growing epidemic of obesity. Non-alcoholic steatohepatitis (NASH), the inflammatory stage of NAFLD, is characterized by lipid accumulation in hepatocytes, chronic inflammation and hepatocyte cell death. Scopoletin and umbelliferone are coumarin-like molecules and have antioxidant, anti-cancer and anti-inflammatory effects. Cytoprotective effects of these compounds have not been described in hepatocytes and the mechanisms of the beneficial effects of scopoletin and umbelliferone are unknown.AIM: To investigate whether scopoletin and/or umbelliferone protect hepatocytes against palmitate-induced cell death. For comparison, we also tested the cytoprotective effect of scopoletin and umbelliferone against bile acid-induced cell death.METHODS: Primary rat hepatocytes were exposed to palmitate (1 mmol/L) or the hydrophobic bile acid glycochenodeoxycholic acid (GCDCA; 50 μmol/L). Apoptosis was assessed by caspase-3 activity assay, necrosis by Sytox green assay, mRNA levels by qPCR, protein levels by Western blot and production of reactive oxygen species (ROS) by fluorescence assay.RESULTS: Both scopoletin and umbelliferone protected against palmitate and GCDCA-induced cell death. Both palmitate and GCDCA induced the expression of ER stress markers. Scopoletin and umbelliferone decreased palmitate- and GCDCA-induced expression of ER stress markers, phosphorylation of the cell death signaling intermediate JNK as well as ROS production.CONCLUSION: Scopoletin and umbelliferone protect against palmitate and bile acid-induced cell death of hepatocytes by inhibition of ER stress and ROS generation and decreasing phosphorylation of JNK. Scopoletin and umbelliferone may hold promise as a therapeutic modality for the treatment of NAFLD.

BACKGROUND: Activated hepatic stellate cells (aHSCs) are the main effector cells during liver fibrogenesis. α-1 adrenergic antagonist doxazosin (DX) was shown to be anti-fibrotic in an in vivo model of liver fibrosis (LF), but the mechanism remains to be elucidated. Recent studies suggest that reversion of LF can be achieved by inducing cellular senescence characterized by irreversible cell-cycle arrest and acquisition of the senescence-associated secretory phenotype (SASP).AIM: To elucidate the mechanism of the anti-fibrotic effect of DX and determine whether it induces senescence.METHODS: Primary culture-activated rat HSCs were used. mRNA and protein expression were measured by qPCR and Western blot, respectively. Cell proliferation was assessed by BrdU incorporation and xCelligence analysis. TGF-β was used for maximal HSC activation. Norepinephrine (NE), PMA and m-3M3FBS were used to activate alpha-1 adrenergic signaling.RESULTS: Expression of Col1α1 was significantly decreased by DX (10 µmol/L) at mRNA (-30 %) and protein level (-50 %) in TGF-β treated aHSCs. DX significantly reduced aHSCs proliferation and increased expression of senescence and SASP markers. PMA and m-3M3FBS reversed the effect of DX on senescence markers.CONCLUSION: Doxazosin reverses the fibrogenic phenotype of aHSCs and induces the senescence phenotype.