Inhibition of endogenous hydrogen sulfide production reduces activation of hepatic stellate cells via the induction of cellular senescence.

In chronic liver injury, quiescent hepatic stellate cells (HSCs) transdifferentiate into activated myofibroblast-like cells and produce large amounts of extracellular matrix components, e.g. collagen type 1. Cellular senescence is characterized by irreversible cell-cycle arrest, arrested cell proliferation and the acquisition of the senescence-associated secretory phenotype (SASP) and reversal of HSCs activation. Previous studies reported that H2S prevents induction of senescence via its antioxidant activity. We hypothesized that inhibition of endogenous H2S production induces cellular senescence and reduces activation of HSCs. Rat HSCs were isolated and culture-activated for 7 days. After activation, HSCs treated with H2S slow-releasing donor GYY4137 and/or DL-propargylglycine (DL-PAG), an inhibitor of the H2S-producing enzyme cystathionine γ-lyase (CTH), as well as the PI3K inhibitor LY294002. In our result, CTH expression was significantly increased in fully activated HSCs compared to quiescent HSCs and was also observed in activated stellate cells in a in vivo model of cirrhosis. Inhibition of CTH reduced proliferation and expression of fibrotic markers Col1a1 and Acta2 in HSCs. Concomitantly, DL-PAG increased the cell-cycle arrest markers Cdkn1a (p21), p53 and the SASP marker Il6. Additionally, the number of ß-galactosidase positive senescent HSCs was increased. GYY4137 partially restored the proliferation of senescent HSCs and attenuated the DL-PAG-induced senescent phenotype. Inhibition of PI3K partially reversed the senescence phenotype of HSCs induced by DL-PAG. Inhibition of endogenous H2S production reduces HSCs activation via induction of cellular senescence in a PI3K-Akt dependent manner. Our results show that cell-specific inhibition of H2S could be a novel target for anti-fibrotic therapy via induced cell senescence.

The landscape of super-enhancer regulates remote target gene transcription through loop domains in adipose tissue of pig.

Background: A super-enhancer (SE) is a huge cluster of multiple enhancers that control the key genes for cell identity and function. The rise of advanced chromatin immunoprecipitation sequencing (ChIP-seq) technology such as Cleavage Under Targets and Tagmentation (CUT&Tag) allows more SEs to be discovered. However, SE studies in Luchuan and Duroc pigs are very rare in animal husbandry. Results: We used the CUT&Tag technique to identify 145 and 378 SEs from the adipose tissues of Luchuan and Duroc pigs, respectively. There were significant differences in the peak coverage ratio of SE peaks in the gene promoter region between the two breeds. Not only that, peak signals at the start and end point of the SE peak profile showed obvious spikes. The proximal target genes of SE were highly expressed compared with the background genes and the typical enhancer target genes. Subsequently, in conjoint analysis with high-throughput chromosome conformation capture sequencing (Hi-C seq) data, we predicted the remote regulatory genes of SE and found that their expression level was related to the distance of SE extended to the loop's anchor, but not the length of loops. According to our prediction model, SEs can maintain promoter accessibility of partial remote target genes through loop domains. Finally, a batch of SEs closely related to fat metabolism traits were obtained by performing a coalition analysis of quantitative trait loci and SE data. Conclusions: This work enabled us to obtain hundreds of SEs from Luchuan and Duroc pigs. Our model provides a new method for predicting the SE remote target genes based on loop domains, and to further explore the potential role of super-enhancer in the regulation of fat metabolism.

Deletion of the mitochondrial calcium uniporter in adipose tissue promotes energy expenditure and alleviates diet-induced obesity.

OBJECTIVE: Studies have shown a correlation between obesity and mitochondrial calcium homeostasis, yet it is unclear whether and how Mcu regulates adipocyte lipid deposition. This study aims to provide new potential target for the treatment of obesity and related metabolic diseases, and to explore the function of Mcu in adipose tissue. METHODS: We firstly investigated the role of mitoxantrone, an Mcu inhibitor, in the regulation of glucose and lipid metabolism in mouse adipocytes (3T3-L1 cells). Secondly, C57BL/6J mice were used as a research model to investigate the effects of Mcu inhibitors on fat accumulation and glucose metabolism in mice on a high-fat diet (HFD), and by using CRISPR/Cas9 technology, adipose tissue-specific Mcu knockdown mice (Mcufl/+ AKO) and Mcu knockout of mice (Mcufl/fl AKO) were obtained, to further investigate the direct effects of Mcu on fat deposition, glucose tolerance and insulin sensitivity in mice on a high-fat diet. RESULTS: We found the Mcu inhibitor reduced adipocytes lipid accumulation and adipose tissues mass in mice fed an HFD. Both Mcufl/+ AKO mice and Mcufl/fl AKO mice were resistant to HFD-induced obesity, compared to control mice. Mice with Mcufl/fl AKO showed improved glucose tolerance and insulin sensitivity as well as reduced hepatic lipid accumulation. Mechanistically, inhibition of Mcu promoted mitochondrial biogenesis and adipocyte browning, increase energy expenditure and alleviates diet-induced obesity. CONCLUSIONS: Our study demonstrates a link between adipocyte lipid accumulation and mCa2+ levels, suggesting that adipose-specific Mcu deficiency alleviates HFD-induced obesity and ameliorates metabolic disorders such as insulin resistance and hepatic steatosis. These effects may be achieved by increasing mitochondrial biosynthesis, promoting white fat browning and enhancing energy metabolism.

Arbutin alleviates fatty liver by inhibiting ferroptosis via FTO/SLC7A11 pathway.

Non-alcoholic fatty liver disease (NAFLD) is a potentially serious disease that affects 30 % of the global population and poses a significant risk to human health. However, to date, no safe, effective and appropriate treatment modalities are available. In recent years, ferroptosis has emerged as a significant mode of cell death and has been found to play a key regulatory role in the development of NAFLD. In this study, we found that arbutin (ARB), a natural antioxidant derived from Arctostaphylos uva-ursi (L.), inhibits the onset of ferroptosis and ameliorates high-fat diet-induced NAFLD in vivo and in vitro. Using reverse docking, we identified the demethylase fat mass and obesity-related protein (FTO) as a potential target of ARB. Subsequent mechanistic studies revealed that ARB plays a role in controlling methylation of the SLC7A11 gene through inhibition of FTO. In addition, we demonstrated that SLC7A11 could alleviate the development of NAFLD in vivo and in vitro. Our findings identify the FTO/SLC7A11 axis as a potential therapeutic target for the treatment of NAFLD. Specifically, we show that ARB alleviates NAFLD by acting on the FTO/SLC7A11 pathway to inhibit ferroptosis.

BATF relieves hepatic steatosis by inhibiting PD1 and promoting energy metabolism.

The rising prevalence of nonalcoholic fatty liver disease (NAFLD) has become a global health threat that needs to be addressed urgently. Basic leucine zipper ATF-like transcription factor (BATF) is commonly thought to be involved in immunity, but its effect on lipid metabolism is not clear. Here, we investigated the function of BATF in hepatic lipid metabolism. BATF alleviated high-fat diet (HFD)-induced hepatic steatosis and inhibited elevated programmed cell death protein (PD)1 expression induced by HFD. A mechanistic study confirmed that BATF regulated fat accumulation by inhibiting PD1 expression and promoting energy metabolism. PD1 antibodies alleviated hepatic lipid deposition. In conclusion, we identified the regulatory role of BATF in hepatic lipid metabolism and that PD1 is a target for alleviation of NAFLD. This study provides new insights into the relationship between BATF, PD1, and NAFLD.

α-1 Adrenergic receptor antagonist doxazosin reverses hepatic stellate cells activation via induction of senescence.

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-ß 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-ß 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.

Hepatic stellate cell senescence in liver fibrosis: Characteristics, mechanisms and perspectives.

Myofibroblasts play an important role in fibrogenesis. Hepatic stellate cells are the main precursors of myofibroblasts. Cellular senescence is the terminal cell fate in which proliferating cells undergo irreversible cell cycle arrest. Senescent hepatic stellate cells were identified in liver fibrosis. Senescent hepatic stellate cells display decreased collagen production and proliferation. Therefore, induction of senescence could be a protective mechanism against progression of liver fibrosis and the concept of therapy-induced senescence has been proposed to treat liver fibrosis. In this review, characteristics of senescent hepatic stellate cells and the essential signaling pathways involved in senescence are reviewed. Furthermore, the potential impact of senescent hepatic stellate cells on other liver cell types are discussed. Senescent cells are cleared by the immune system. The persistence of senescent cells can remodel the microenvironment and interact with inflammatory cells to induce aging-related dysfunction. Therefore, senolytics, a class of compounds that selectively induce death of senescent cells, were introduced as treatment to remove senescent cells and consequently decrease the disadvantageous effects of persisting senescent cells. The effects of senescent hepatic stellate cells in liver fibrosis need further investigation.

Estimating the Impacts of Hospitals' Organisational and Geographical Characteristics on the Adoption of Health Information Technology in Mongolian Hospitals.

BACKGROUND: The adoption of health information technology (HIT) is an important measure for improving healthcare quality and safety, which is affected by many hospital factors, but it has not yet been estimated in the Mongolian hospital sectors. This study examines how hospitals' organisational and geographical characteristics influence the adoption of HIT in Mongolian tertiary and secondary care hospitals. METHODS: А cross-sectional study involving the executive directors and medical equipment engineers was conducted in 39 hospitals. Data acquired from questionnaires are (1) hospitals' organisational and geographical characteristics, including bed-size capacity, ownership type, status, and location of the hospitals, and (2) the adoption rate of HIT, and its categories are based on the Health Information and Management Systems Society's classification (2002). The dependent variable was measured as numbers and the rate of HIT programs adopted clinical, administrative, and strategic information technologies (IT). A regression analysis was used to estimate the factors of impact on the adoption of clinical, administrative, and strategic IT. RESULTS: We found a concerning relationship between the characteristics and adoption of HITs. On average, the number of HIT programs adopted was 18, covering nine clinical IT programs, six administrative IT programs, and three strategic IT programs. The adoption rate of overall HIT was 33.29% in the hospitals. In regression analysis, the organisational and geographical characteristics' impact and HIT adoption of hospitals was positively associated with large bed-size (clinical IT: ß = 0.256, P < 0.001; administrative IT: ß = 0.3654, P < 0.001; strategic IT: ß = 0.0006, P < 0.001), for-profit (strategic IT: ß = 0.1995, P < 0.01), teaching (clinical IT: ß = 0.2560, P < 0.05; administrative IT: ß = 0.1985, P < 0.05; strategic IT: ß = 0.2236, P < 0.01), and urban location (clinical IT: ß = 0.2840, P < 0.001, administrative IT: ß = 0.2256, P < 0.01; strategic IT: ß = 0.2256, P < 0.001). CONCLUSION: Our study found that the HIT adoption rate in Mongolia is poor, and its adoption is mainly positively associated with bed-size capacity, status, and location of the hospitals. Also, we found that the ownership type is partially affected HIT adoption.

Oxidative stress is associated with suspected non-alcoholic fatty liver disease and all-cause mortality in the general population.

BACKGROUND & AIMS: Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation, inflammation and an imbalanced redox homeostasis. We hypothesized that systemic free thiol levels, as a proxy of systemic oxidative stress, are associated with NAFLD. METHODS: Protein-adjusted serum free thiol concentrations were determined in participants from the Prevention of Renal and Vascular End-Stage Disease (PREVEND) cohort study (n = 5562). Suspected NAFLD was defined by the Fatty Liver Index (FLI ≥ 60) and Hepatic Steatosis Index (HSI > 36). RESULTS: Protein-adjusted serum free thiols were significantly reduced in subjects with FLI ≥ 60 (n = 1651). In multivariable logistic regression analyses, protein-adjusted serum free thiols were associated with NAFLD (FLI ≥ 60) (OR per doubling of concentration: 0.78 [95% CI 0.64-0.96], P = .016) even when adjusted for potential confounding factors, including systolic blood pressure, diabetes, current smoking, use of alcohol and total cholesterol (OR 0.80 [95% CI 0.65-0.99], P = .04). This association lost its significance (OR 0.94 [95% CI 0.73-1.21], P = .65) after additional adjustment for high-sensitive C-reactive protein. Stratified analyses showed significantly differential associations of protein-adjusted serum free thiol concentrations with suspected NAFLD for gender (P < .02), hypertension (P < .001) and hypercholesterolemia (P < .003). Longitudinally, protein-adjusted serum free thiols were significantly associated with the risk of all-cause mortality in subjects with NAFLD (FLI ≥ 60) (HR 0.27 [95% CI 0.17-0.45], P < .001). CONCLUSION: Protein-adjusted serum free thiol levels are reduced and significantly associated with all-cause mortality in subjects with suspected NAFLD. Quantification of free thiols may be a promising, minimally invasive strategy to improve detection of NAFLD and associated risk of all-cause mortality in the general population.

Hydrogen sulfide stimulates activation of hepatic stellate cells through increased cellular bio-energetics.

Hepatic fibrosis is caused by chronic inflammation and characterized as the excessive accumulation of extracellular matrix (ECM) by activated hepatic stellate cells (HSCs). Gasotransmitters like NO and CO are known to modulate inflammation and fibrosis, however, little is known about the role of the gasotransmitter hydrogen sulfide (H2S) in liver fibrogenesis and stellate cell activation. Endogenous H2S is produced by the enzymes cystathionine ß-synthase (CBS), cystathionine γ-lyase (CTH) and 3-mercaptopyruvate sulfur transferase (MPST) [1]. The aim of this study was to elucidate the role of endogenously produced and/or exogenously administered H2S on rat hepatic stellate cell activation and fibrogenesis. Primary rat HSCs were culture-activated for 7 days and treated with different H2S releasing donors (slow releasing donor GYY4137, fast releasing donor NaHS) or inhibitors of the H2S producing enzymes CTH and CBS (DL-PAG, AOAA). The main message of our study is that mRNA and protein expression level of H2S synthesizing enzymes are low in HSCs compared to hepatocytes and Kupffer cells. However, H2S promotes hepatic stellate cell activation. This conclusion is based on the fact that production of H2S and mRNA and protein expression of its producing enzyme CTH are increased during hepatic stellate cell activation. Furthermore, exogenous H2S increased HSC proliferation while inhibitors of endogenous H2S production reduce proliferation and fibrotic makers of HSCs. The effect of H2S on stellate cell activation correlated with increased cellular bioenergetics. Our results indicate that the H2S generation in hepatic stellate cells is a target for anti-fibrotic intervention and that systemic interventions with H2S should take into account cell-specific effects of H2S.