Up-regulation of components of the renin-angiotensin system in liver fibrosis in the rat induced by CCL4. Res Vet Sci. 2013;95:54-58. [PMID: 23433841 PMCID: PMC7111816 DOI: 10.1016/j.rvsc.2013.01.028]

Non-alcoholic fatty pancreas disease: an updated review

Ectopic accumulation of fat can cause a variety of metabolic diseases, and the emerging non-alcoholic fatty pancreas disease (NAFPD) is increasingly being recognized by clinicians as a cause for concern. NAFPD is a disease caused by abnormal accumulation of adipose tissue in the pancreas, which is related to obesity. The main feature of NAFPD is death of acinar cells, which are then replaced by adipose cells. However, the underlying molecular mechanisms have not been fully explored. Obesity, aging, and metabolic syndrome are independent risk factors for the occurrence and development of NAFPD. Studies have shown that NAFPD leads to insulin resistance and pancreatic dysfunction, increases the risk of diabetes mellitus, worsens the severity of pancreatitis, and is significantly correlated with pancreatic cancer and postoperative pancreatic fistula. There is no standard treatment for NAFPD; exercise, a balanced diet, and lifestyle can help reduce pancreatic fat; however, other treatment modalities such as drugs and bariatric surgery are still being explored. The specific pathological mechanism of NAFPD remains unclear, and its potential association with various clinical diseases requires further study. This review summarizes the etiology, diagnosis, clinical consequences, and potential therapeutic strategies of NAFPD.

Renin-angiotensin system inhibitors and risk of hepatocellular carcinoma among patients with hepatitis B virus infection

BACKGROUND

Hepatitis B virus (HBV) infection is a common cause of liver-related morbidity and mortality. Evidence suggests that angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) decrease liver fibrosis, an intermediate step between liver injury and hepatocellular carcinoma (HCC). Our aim was to investigate the association between the use of ACEIs and ARBs on incident HCC and liver-related mortality among patients with HBV infection.

METHODS

We conducted a population-based study on a new-user cohort of patients seen at 24 hospitals across China. We included adult patients with HBV infection who started ACEIs or ARBs (ACEIs/ARBs), or calcium channel blockers or thiazide diuretics (CCBs/THZs) from January 2012 to December 2022. The primary outcome was incident HCC; secondary outcomes were liver-related mortality and new-onset cirrhosis. We used propensity score matching and Cox proportional hazards regression to estimate the hazard ratio (HR) and 95% confidence intervals (CIs) of study outcomes.

RESULTS

Among 32 692 eligible patients (median age 58 [interquartile range (IQR) 48-68] yr, and 18 804 male [57.5%]), we matched 9946 pairs of patients starting ACEIs/ARBs or CCBs/THZs. During a mean follow-up of 2.3 years, the incidence rate of HCC per 1000 person-years was 4.11 and 5.94 among patients who started ACEIs/ARBs and CCBs/THZs, respectively, in the matched cohort. Use of ACEIs/ARBs was associated with lower risks of incident HCC (HR 0.66, 95% CI 0.50-0.86), liver-related mortality (HR 0.77, 95% CI 0.64-0.93), and new-onset cirrhosis (HR 0.81, 95% CI 0.70-0.94).

INTERPRETATION

In this cohort of patients with HBV infection, new users of ACEIs/ARBs had a lower risk of incident HCC, liver-related mortality, and new-onset cirrhosis than new users of CCBs/THZs.

Targeting mevalonate pathway by zoledronate ameliorated pulmonary fibrosis in a rat model: Promising therapy against post-COVID-19 pulmonary fibrosis

BACKGROUND

Rho kinase (ROCK) pathway plays a critical role in post-COVID-19 pulmonary fibrosis (PCPF) and its intervention with angiotensin-converting enzyme 2 (ACE2) and vascular endothelial growth factor (VEGF) will be a potential therapeutic target.

OBJECTIVES

The present study was conducted to investigate the efficacy of zoledronate (ZA) on carbon tetrachloride (CCl4) induced pulmonary fibrosis (PF) in rats through targeting ACE2, ROCK, and VEGF signaling pathways.

METHODS

Fifty male Wistar rats were divided into five groups: control, vehicle-treated, PF, PF-ZA 50, and PF-ZA 100 groups. ZA was given in two different doses 100 and 50 μg/kg/week intraperitoneally. After anesthesia, mean arterial blood pressure (MBP) was measured. After scarification, lung coefficient was calculated. Lung levels of ACE 2, interleukin-1β (IL-1β), transforming growth factor-β (TGF-β), VEGF, glutathione (GSH), and superoxide dismutase (SOD) were measured. Expression of ROCK, phosphorylated myosin phosphatase target subunit 1 (P-MYPT1), and matrix metalloproteinase (MMP-1), along with histopathological changes and immune-histochemical staining for lung α-smooth muscle actin (α-SMA), tumor necrosis factor-alpha (TNFα), and caspase-3, were evaluated.

RESULTS

ZA significantly prevented the decrease in MBP. ZA significantly increased ACE2, GSH, and SOD and significantly decreased IL-1β, TGF-β, and VEGF in lung in comparison to PF group. ZA prevented the histopathological changes induced by CCl4. ZA inhibited lung expression of ROCK, P-MYPT1, MMP-1, α-SMA, TNFα, and caspase-3 with significant differences favoring the high dose intervention.

CONCLUSION

ZA in a dose-dependent manner prevented the pathological effect of CCl4 in the lung by targeting mevalonate pathway. It could be promising therapy against PCPF.

Transcriptomic analysis reveals pharmacological mechanisms mediating efficacy of Yangyinghuoxue Decoction in CCl4-induced hepatic fibrosis in rats

Background and purpose

As a traditional Chinese medicine formula, Yangyinghuoxue Decoction (YYHXD) is used clinically for therapy of hepatic fibrosis. The pharmacological profile of YYHXD comprises multiple components acting on many targets and pathways, but the pharmacological mechanisms underlying its efficacy have not been thoroughly elucidated. This study aimed at probing the pharmacological mechanisms of YYHXD in the treatment of hepatic fibrosis.

Methods

YYHXD aqueous extract was prepared and quality control using HPLC-MS fingerprint analysis was performed. A CCl4-induced rat model of hepatic fibrosis was established, and animals were randomly assigned to six groups: control, low-dose YYHXD (L-YYHXD), medium-dose YYHXD (M-YYHXD), high-dose YYHXD (H-YYHXD), CCl4 model, and colchicine group. Rats in the treatment groups received daily oral administration of YYHXD (5, 10, or 20 g/kg) or colchicine (0.2 mg/kg) for 6 weeks, while the control and model groups received distilled water. Histological analysis, including hematoxylin and eosin (HE) and Masson's trichrome staining, was performed to evaluate hepatic fibrosis. Serum biochemical markers, such as AST, ALT, HA, and LN, were measured. Inflammatory cytokines (IL-6 and TNF-α) and oxidative stress indicators (SOD, GSH-Px, and MDA) in hepatic tissue were also assessed. Additionally, transcriptomic analysis using RNA-sequencing was conducted to identify differentially expressed genes (DEGs) between the control, CCl4 model, and H-YYHXD groups. Bioinformatics analysis, including differential expression analysis, protein-protein interaction analysis, and functional enrichment analysis, were performed to probe the pharmacological mechanisms of YYHXD. The regulatory effects of YYHXD on fatty acid metabolism and biosynthesis were further confirmed by Oil Red O staining, enzyme activity assays, qPCR, and Western blotting. Western blotting and immunofluorescence staining also validated the involvement of the AMPK signaling pathway in the occurrence and progression of hepatic fibrosis.

Results

HE and Masson's trichrome staining revealed reduced collagen deposition and improved liver architecture in YYHXD groups compared to the CCl4 model group. Serum biochemical markers, including AST, ALT, HA, and LN, were significantly improved in the YYHXD-treated groups compared to the CCl4 model group. The levels of inflammatory cytokines (IL-6 and TNF-α) and oxidative stress indicators (decreased SOD and GSH-Px, increased MDA) in hepatic tissue were significantly ameliorated by YYHXD treatment compared to the CCl4 model group. Moreover, 96 genes implicated in YYHXD therapy of hepatic fibrosis were screened from the transcriptomic data, which were principally enriched in biological pathways such as fatty acid metabolism and biosynthesis, and the AMPK signaling pathway. Oil Red O staining showed reduced hepatic lipid accumulation by YYHXD in a dose-dependent manner, along with decreased serum TG, TC, and LDL-C levels. Additionally, qPCR and Western blot analyses demonstrated upregulated mRNA and protein expression of key enzymes involved in fatty acid metabolism and biosynthesis, Fasn and Fads2, modulated by YYHXD. YYHXD also dose-dependently enhanced phosphorylation of AMPK as evidenced by Western blotting and immunofluorescence assays.

Conclusion

YYHXD ameliorated CCl4-induced hepatic fibrosis in rats through pharmacological mechanisms that involved manifold targets and pathways, including aliphatic acid synthesis and metabolism pathways and the AMPK signaling pathway. This study provided a reference and basis for further research and clinical utilization of YYHXD.

Molecular mechanisms underlying SARS-CoV-2 hepatotropism and liver damage

In coronavirus disease 2019 (COVID-19), severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) primarily targets the respiratory system, but evidence suggests extrapulmonary organ involvement, notably in the liver. Viral RNA has been detected in hepatic tissues, and in situ hybridization revealed virions in blood vessels and endothelial cells. Electron microscopy confirmed viral particles in hepatocytes, emphasizing the need for understanding hepatotropism and direct cytopathic effects in COVID-19-related liver injury. Various factors contribute to liver injury, including direct cytotoxicity, vascular changes, inflammatory responses, immune reactions from COVID-19 and vaccinations, and drug-induced liver injury. Although a typical hepatitis presentation is not widely documented, elevated liver biochemical markers are common in hospitalized COVID-19 patients, primarily showing a hepatocellular pattern of elevation. Long-term studies suggest progressive cholestasis may affect 20% of patients with chronic liver disease post-SARS-CoV-2 infection. The molecular mechanisms underlying SARS-CoV-2 infection in the liver and the resulting liver damage are complex. This "Editorial" highlights the expression of the Angiotensin-converting enzyme-2 receptor in liver cells, the role of inflammatory responses, the impact of hypoxia, the involvement of the liver's vascular system, the infection of bile duct epithelial cells, the activation of hepatic stellate cells, and the contribution of monocyte-derived macrophages. It also mentions that pre-existing liver conditions can worsen the outcomes of COVID-19. Understanding the interaction of SARS-CoV-2 with the liver is still evolving, and further research is required.

An Egg White-Derived Peptide Enhances Systemic Insulin Sensitivity and Modulates Markers of Non-Alcoholic Fatty Liver Disease in Obese, Insulin Resistant Mice

Non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of the metabolic syndrome, is a global health problem. Currently, no pharmacological treatment is approved for NAFLD. Natural health products, including bioactive peptides, are potential candidates to aid in the management of metabolic syndrome-related conditions, including insulin resistance and obesity. In this study, we hypothesized that an egg-white-derived bioactive peptide QAMPFRVTEQE (Peptide 2) would improve systemic and local white adipose tissue insulin sensitivity, thereby preventing high-fat diet-induced exacerbation of pathological features associated with NAFLD, such as lipid droplet size and number, inflammation, and hepatocyte hypertrophy in high-fat diet-fed mice. Similar to rosiglitazone, Peptide 2 supplementation improved systemic insulin resistance during the hyperinsulinemic-euglycemic clamp and enhanced insulin signalling in white adipose tissue, modulating ex vivo lipolysis. In the liver, compared with high-fat diet fed animals, Peptide 2 supplemented animals presented decreased hepatic cholesterol accumulation (p < 0.05) and area of individual hepatic lipid droplet by around 50% (p = 0.09) and reduced hepatic inflammatory infiltration (p < 0.05) whereas rosiglitazone exacerbated steatosis. In conclusion, Peptide 2 supplementation improved insulin sensitivity and decreased hepatic steatosis, unlike the insulin-sensitizing drug rosiglitazone.

Inferring microenvironmental regulation of gene expression from single-cell RNA sequencing data using scMLnet with an application to COVID-19

Inferring how gene expression in a cell is influenced by cellular microenvironment is of great importance yet challenging. In this study, we present a single-cell RNA-sequencing data based multilayer network method (scMLnet) that models not only functional intercellular communications but also intracellular gene regulatory networks (https://github.com/SunXQlab/scMLnet). scMLnet was applied to a scRNA-seq dataset of COVID-19 patients to decipher the microenvironmental regulation of expression of SARS-CoV-2 receptor ACE2 that has been reported to be correlated with inflammatory cytokines and COVID-19 severity. The predicted elevation of ACE2 by extracellular cytokines EGF, IFN-γ or TNF-α were experimentally validated in human lung cells and the related signaling pathway were verified to be significantly activated during SARS-COV-2 infection. Our study provided a new approach to uncover inter-/intra-cellular signaling mechanisms of gene expression and revealed microenvironmental regulators of ACE2 expression, which may facilitate designing anti-cytokine therapies or targeted therapies for controlling COVID-19 infection. In addition, we summarized and compared different methods of scRNA-seq based inter-/intra-cellular signaling network inference for facilitating new methodology development and applications.

Liraglutide Attenuates Non-Alcoholic Fatty Liver Disease in Mice by Regulating the Local Renin-Angiotensin System

The renin-angiotensin system (RAS) is involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD) and represents a potential therapeutic target for NAFLD. Glucagon-like peptide-1 (GLP-1) signaling has been shown to regulate the RAS within various local tissues. In this study, we aimed to investigate the functional relationship between GLP-1 and the local RAS in the liver during NAFLD. Wild-type and ACE2 knockout mice were used to establish a high-fat-induced NAFLD model. After the mice were treated with liraglutide (a GLP-1 analogue) for 4 weeks, the key RAS component genes were up-regulated in the liver of NAFLD mice. Liraglutide treatment regulated the RAS balance, preventing a reduction in fatty acid oxidation gene expression and increasing gluconeogenesis and the expression of inflammation-related genes caused by NAFLD, which were impaired in ACE2 knockout mice. Liraglutide-treated HepG2 cells exhibited activation of the ACE2/Ang1-7/Mas axis, increased fatty acid oxidation gene expression, and decreased inflammation, which could be reversed by A779 and AngII. These results indicate that the local RAS in the liver becomes overactivated in response to NAFLD. Moreover, ACE2 knockout increases the severity of liver steatosis. Liraglutide has a negative and antagonistic effect on the ACE/AngII/AT1R axis, a positive impact on the ACE2/Ang1-7/Mas axis, and is mediated through the PI3K/AKT pathway. This may represent a potential new mechanism by which liraglutide improves NAFLD.

Non-alcoholic fatty pancreas disease - practices for clinicians

Obesity is a growing health burden worldwide, increasing the risk for several diseases featuring the metabolic syndrome - type 2 diabetes mellitus, dyslipidemia, non-alcoholic fatty liver disease and cardiovascular diseases. With the increasing epidemic of obesity, a new pathologic condition has emerged as a component of the metabolic syndrome - that of non-alcoholic fatty pancreas disease (NAFPD). Similar to non-alcoholic fatty liver disease (NAFLD), NAFPD comprises a wide spectrum of disease - from deposition of fat in the pancreas - fatty pancreas, to pancreatic inflammation and possibly pancreatic fibrosis. In contrast with NAFLD, diagnostic evaluation of NAFPD is less standardized, consisting mostly in imaging methods. Also the natural evolution of NAFPD and its association with pancreatic cancer is much less studied. Not least, the clinical consequences of NAFPD remain largely presumptions and knowledge about its metabolic impact is limited. This review will cover epidemiology, pathogenesis, diagnostic evaluation tools and treatment options for NAFPD, with focus on practices for clinicians.

Beneficial effects of losartan or telmisartan on the local hepatic renin-angiotensin system to counter obesity in an experimental model

BACKGROUND

Obesity has been associated with hepatic overexpression of the renin-angiotensin system (RAS).

AIM

To evaluate the action of two angiotensin II (ANGII) receptor blockers (losartan or telmisartan) on the modulation of local hepatic RAS and the resulting metabolic effects in a diet-induced obesity murine model.

METHODS

Twenty C57BL/6 mice were randomly divided into two nutritional groups for 10 wk: control group (C, n = 5, 10% of energy as fat) or high-fat group (HF, n = 15, 50% of energy as fat). After treatment started, the HF group was randomly divided into three groups: untreated HF group (n = 5), HF treated with losartan (HFL, n = 5) and HF treated with telmisartan (HFT, n = 5). The treatments lasted for 5 wk, and the dose was 10 mg/kg body mass.

RESULTS

HF diet induced body mass gain (+28%, P < 0.0001), insulin resistance (+69%, P = 0.0079), high hepatic triacylglycerol (+127%, P = 0.0004), and overexpression of intrahepatic angiotensin-converting enzyme (ACE) 1/ ANGII type 1 receptor (AT1r) (+569.02% and +141.40%, respectively, P < 0.0001). The HFL and HFT groups showed higher ACE2/rMAS gene expression compared to the HF group (ACE2: +465.57%, P = 0.0002 for HFL and +345.17%, P = 0.0049 for HFT; rMAS: +711.39%, P < 0.0001 for HFL and +539.75%, P < 0.0001 for HFT), followed by reduced insulin/glucose ratio (-30% for HFL and -33% for HFT, P = 0.0181), hepatic triacylglycerol levels (-28%, P = 0.0381 for HFL; and -45%, P = 0.0010 for HFT, and Plin2 expression.

CONCLUSION

Modulation of the intrahepatic RAS, with favored involvement of the ACE2/rMAS axis over the ACE1/AT1r axis after losartan or telmisartan treatments, caused hepatic and metabolic beneficial effects as demonstrated by reduced hepatic triacylglycerol levels coupled with reduced PLIN 2 expression and improved glycemic control.

Liver

The discovery that renin–angiotensin system (RAS) components are locally expressed in the liver tissue, pointed out to a role for this system in the pathogenesis of hepatic fibrosis and cirrhosis. The RAS counter-regulatory axis composed by the angiotensin converting enzyme 2 (ACE2), angiotensin-(1-7) [Ang-(1-7)] and Mas receptor mediates pro-inflammatory, pro-thrombotic, and pro-fibrotic processes, frequently opposing the classical RAS arm (ACE-Ang II-AT₁ receptor) actions. Therefore, the balance between both RAS axes most likely affects the clinical and histopathological expression of liver diseases. It is worth noticing that liver diseases are major causes of morbidity and mortality worldwide. Without proper treatment, all types of chronic hepatitis will progress to end-stage liver diseases, including cirrhosis, liver failure, and hepatocellular carcinoma, which ultimately lead to death. In this context, to better comprehend the role of RAS components in liver failure might pave the way for the search of potential predictive biomarkers as well as the development of novel therapeutic approaches. Valuable data have been generated from preclinical and clinical studies. Herein, we summarize the current evidence, mainly focusing in the ACE2-Ang-(1-7)-Mas receptor arm, regarding the role of RAS in liver diseases. The therapeutic potential of the modulation of RAS molecules in liver diseases is also discussed.

BML-111 equilibrated ACE-AngII-AT1R and ACE2-Ang-(1-7)-Mas axis to protect hepatic fibrosis in rats

BACKGROUND

It was recently reported Lipoxins (LXs) had protective effects on fibrous diseases, and renin-angiotensin-aldosterone system (RAAS) had played vital and bidirectional roles in hepatic fibrosis. In this paper, a hepatic fibrosis model, induced by carbon tetrachloride (CCL₄) in rats, was used to observe the relations between RAAS and LXs, as well as to further explore the alternative anti-fibrosis mechanisms of LXs.

METHODS

The model was evaluated by morphological observations and biochemical assays. The activities and contents of angiotensin converting enzyme (ACE) and angiotensin converting enzyme 2 (ACE2) were examined through assay kits and ELISA. The expression levels of angiotensinII (AngII), Angiotensin II type 1 receptor (AT1R), angiotensin-(1-7) (Ang-1-7), and Mas were all measured using real time PCR, ELISA, and Western blot.

RESULTS

The model was established successfully and BML-111 significantly ameliorated CCL₄-induced hepatic fibrosis, including reduction inflammation injury, decrease extracellular matrix deposition, and improvement hepatic functions. Furthermore, BML-111 could obviously decrease not only the activities of ACE but also the expression levels of ACE, AngII,and AT1R, which were induced by CCL₄. On the other hand, BML-111 could markedly increase the activities of ACE2, besides the expression levels of ACE2, Ang-(1-7) and Mas. More importantly, BOC-2, a lipoxin A₄ receptor blocker, could reverse all these phenomena.

CONCLUSIONS

Equilibrating ACE-AngII-AT1R axis and ACE2-Ang-(1-7)-Mas axis mediated the protective effect of BML-111 on hepatic fibrosis in rats.

Renin angiotensin system in liver diseases: Friend or foe?

In the last three decades, the understanding of the renin angiotensin system (RAS) has been changed by the discoveries of functional local systems, novel biologically active peptides, additional specific receptors, alternative pathways of angiotensin (Ang) II generation, and new roles for enzymes and precursor components other than those in Ang II synthesis. In this regard, the discovery that Ang-(1-7) opposes the pressor, proliferative, pro-fibrotic, and pro-inflammatory effects mediated by Ang II has contributed to the realization that the RAS is composed of two axes. The first axis consists of the angiotensin-converting enzyme (ACE), with Ang II as the end product, and the angiotensin type 1 (AT1) receptor as the main effector mediating the biological actions of Ang II. The second axis results from ACE2-mediated hydrolysis of Ang II, leading to the production of Ang-(1-7), with the Mas receptor as the main effector conveying the vasodilatory, anti-proliferative, anti-fibrotic, and anti-inflammatory effects of Ang-(1-7). Experimental and clinical studies have shown that both axes of the RAS may take part in the pathogenesis of liver diseases. In this manuscript, we summarize the current evidence regarding the role of RAS in hepatic cirrhosis and its complications, including hemodynamic changes and hepatorenal syndrome. The therapeutic potential of the modulation of RAS molecules in liver diseases is also discussed.

Hepatic structural enhancement and insulin resistance amelioration due to AT1 receptor blockade

Over the last decade, the role of renin-angiotensin system (RAS) on the development of obesity and its comorbidities has been extensively addressed. Both circulating and local RAS components are up-regulated in obesity and involved in non-alcoholic fatty liver disease onset. Pharmacological manipulations of RAS are viable strategies to tackle metabolic impairments caused by the excessive body fat mass. Renin inhibitors rescue insulin resistance, but do not have marked effects on hepatic steatosis. However, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers (ARB) yield beneficial hepatic remodeling. ARBs elicit body mass loss and normalize insulin levels, tackling insulin resistance. Also, this drug class increases adiponectin levels, besides countering interleukin-6, tumoral necrosis factor-alpha, and transforming growth factor-beta 1. The latter is essential to prevent from liver fibrosis. When conjugated with peroxisome proliferator-activated receptor (PPAR)-alpha activation, ARB fully rescues fatty liver. These effects might be orchestrated by an indirect up-regulation of MAS receptor due to angiotensin II receptor type 1 (AT1R) blockade. These associations of ARB with PPAR activation and ACE2-angiotensin (ANG) (1-7)-MAS receptor axis deserve a better understanding. This editorial provides a brief overview of the current knowledge regarding AT1R blockade effects on sensitivity to insulin and hepatic structural alterations as well as the intersections of AT1R blockade with peroxisome proliferator-activated receptor activation and ACE2-ANG (1-7) - MAS receptor axis.

Swertiamarin Attenuates Experimental Rat Hepatic Fibrosis by Suppressing Angiotensin II-Angiotensin Type 1 Receptor-Extracellular Signal-Regulated Kinase Signaling

The rennin-angiotensin system (RAS) is crucial in hepatic fibrosis development, and therapies targeting this system may be a promising treatment for hepatic fibrosis. In this study, we investigated the effects of swertiamarin (Swe), an ethanol extract of Gentiana manshurica Kitag, on hepatic fibrosis and its underlying mechanisms through regulating RAS. Primary rat hepatic stellate cells (HSCs) were isolated and treated with angiotensin II (Ang II) with or without Swe and losartan. The proliferation and activation of HSCs were measured. Rat hepatic fibrosis was induced by intraperitoneal dimethylnitrosamine (DMN) injection for 4 weeks. Rats were treated with Swe or losartan from the third week until the end of the experiment. Hydroxyproline content in liver tissue was assayed with Jamall's method, and liver collagen deposition was visualized using Sirius red staining. RAS components were analyzed by Western blot, immunofluorescent staining, and real-time reverse-transcription polymerase chain reaction. The results showed that Swe significantly inhibited Ang II-induced HSC proliferation and activation. Swe also significantly suppressed DMN-induced α-smooth muscle actin production in rat livers and improved liver function. Swe partially inhibited Ang II-induced angiotensin type 1 receptor (AT1R) up-regulation and suppressed Ang II-induced extracellular signal-regulated kinase (ERK) and c-jun phosphorylation in HSCs. In the DMN-treated rats, Swe treatment significantly inhibited the plasma Ang II levels. DMN-induced AT1R up-regulation, and phosphorylation of ERK and c-jun in rat liver were also inhibited by Swe. In conclusion, Swe may attenuate hepatic fibrosis through inhibiting HSC activation by regulating the RAS.

Impact of hepatic immunoreactivity of angiotensin-converting enzyme 2 on liver fibrosis due to non-alcoholic steatohepatitis

BACKGROUND

We aimed to evaluate the hepatic immunoreactivity of angiotensin-converting enzyme 2 (ACE2) in non-alcoholic steatohepatitis (NASH) patients, elucidate its association with the clinicopathological characteristics and also determine its role in fibrosis progression.

METHODS

The consecutive biopsy proven NASH patients were subdivided into two groups according to their fibrosis score. Fibrotic stages<3 in mild fibrosis group and fibrotic stages ≥ 3 in advanced fibrosis depending on the presence of bridging fibrosis. Liver biopsy specimens were immunohistochemically stained for ACE2 immunoreactivity. Demographics and clinical properties were compared between the groups. Univariate and multivariate analysis were also performed to evaluate the independent predicting factors for the presence of advanced liver fibrosis caused by NASH.

RESULTS

One hundred and eight patients were enrolled in the study. Out of this, ninety-four patients representing 87% were classified as mild fibrosis group, whilst fourteen representing 13% were in advanced fibrosis group. We compared high hepatic immunoreactivity of ACE2 between mild and advanced fibrosis groups and found a statistically significant difference 65.9% vs 28.5%, respectively and P=0.008. Hepatic ACE2 immunoreactivity was inversely correlated with the fibrosis score (r: -0.337; P<0.001). The significant variables in the univariate analysis were then evaluated in multivariate logistic regression analysis and hepatic ACE2 immunoreactivity was an independent predicting factor of liver fibrosis [odds ratio (OR): 0.194; 95% confidence interval (CI): 0.082-0.897, P=0.036].

CONCLUSION

Hepatic immunoreactivity of ACE2 was inversely correlated with the liver fibrosis among biopsy proven NASH patients and it was also an independent predicting factor of advanced fibrosis.

Effects of Yinchenhao decoction on self-regulation of renin-angiotensin system by targeting angiotensin converting enzyme 2 in bile duct-ligated rat liver

In order to investigate whether Yinchenhao decoction (YCHD) attenuates hepatic fibrogenesis in the bile duct ligation (BDL) model via recovering and restoring the self-regulation and balance of the renin-angiotensin system (RAS), 33 specific-pathogen-free (SPF) male Sprague-Dawley rats with common BDL and scission were randomly divided into five groups as follows: G1, the sham group (n=4); G2, BDL 7-day group (n=5); G3, BDL+YCHD 430 mg/mL (n=8); G4, BDL+losartan 0.65 mg/mL (ARB group, n=8); G5, model group (BDL without any treatment, n=8). YCHD and losartan (10 mL·kg(-1)·day(-1)) were given by gastric gavage for 16 days following BDL in G3 and G4 groups, respectively. The effect of YCHD on liver fibrosis and the detailed molecular mechanisms were assessed by liver function including total bilirubin (TBIL), direct bilirubin (DBIL), indirect bilirubin (IDBIL), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Histological changes were observed by transmission electron microscopy (TEM) and Masson trichrome staining. Western blotting was used to detect the protein expression level of the renin-angiotensin system (RAS) components including angiotensin converting enzyme (ACE), angiotensin II type 1 receptor (AT1R), ACE2, angiotensin II (AngII) as well as transforming growth factor β1 (TGFβ1). The experimental data were analyzed by principle component analytical method of pattern recognition. The results showed that biochemically, serum TBIL, DBIL, IDBIL, ALT and AST levels were markedly increased following BDL as compared with the sham group (P<0.05). Serum TBIL, IDBIL and DBIL levels in G3 group were dramatically decreased as compared with G5 and G4 groups (P<0.05). Serum AST level in G3 was significantly lowered than in G5 group (P<0.05), but there was no significant difference in ALT among G3, G4 and G5 groups (P>0.05). Histologically, livers in G3 group showed less hepatocytes necrosis, less bile duct hyperplasia and less collagen formation than in G4 and G5 groups. The protein expression levels of ACE2, ACE, AngII, AT1R and TGFβ1 in G2, G3 and G4 groups were significantly higher than in sham group (P<0.05), and lower than in G5 group (P<0.05). However, the differences among G2, G3 and G4 groups were not significant (P>0.05). ACE2 protein expression in G3 group was significantly higher than in G2 group (P<0.05) and there was no significant difference in comparison with G4 group (P>0.05). Moreover, the protein expression of TGFβ1 in G3 group was significantly lower than in G5 and G4 groups (P<0.05). Our findings suggest that the antifibrotic effects of YCHD may be associated with the decreased classical RAS pathway components and TGFβ1 downexpression so as to recover and rebuild self-regulation of the RAS by elevating the protein expression of ACE2.

The role of renin-angiotensin system modulation on treatment and prevention of liver diseases

The renin-angiotensin system (RAS) is now recognized as an important modulator of body metabolic processes. The discovery of angiotensin-converting enzyme 2 (ACE2) has renewed interest in the potential therapeutic role of RAS modulation. Recent studies have pointed out the importance of the local balance between ACE/Ang-II/AT1 and ACE2/Ang-(1-7)/Mas arms to avoid liver metabolic diseases. Furthermore, non-alcoholic fatty liver disease is an increasing health problem that includes a spectrum of hepatic steatosis, steatohepatitis and fibrosis. Some new studies revealed that RAS imbalance appears to promote hepatic fibrogenesis; while the activation of ACE2/Ang-(1-7)/Mas counter-regulatory axis is able to prevent liver injuries. In this context, the aim of the present review is to discuss the importance of RAS in the development and prevention of liver disease. AT1 receptor activation by Ang II induces hepatic stellate cell contraction and proliferation, causes oxidative stress, endothelial dysfunction, cell growth and inflammation. In addition, both AT1 blocker administration and ACE inhibitors lead to a reduction in inflammation and improvement of hepatic fibrosis. Conversely, Ang-(1-7) infusion reduces fibrosis and proliferation mainly by suppression of hepatic stellate cell activation; Mas receptor antagonism aggravates liver fibrosis and severe liver steatosis. In conclusion, the use of ACE/Ang II/AT1 axis inhibitors associated with ACE2/Ang(1-7)/Mas axis activation is a promising new strategy serving as a novel therapeutic regimen to prevent and treat chronic liver diseases as well as acute liver injury.