Effects of 1-year administration of olmesartan on portal pressure and TGF-beta1 in selected patients with cirrhosis: a randomized controlled trial

The Renin-Angiotensin System in Liver Disease

The renin-angiotensin system (RAS) is a complex homeostatic entity with multiorgan systemic and local effects. Traditionally, RAS works in conjunction with the kidney to control effective arterial circulation, systemic vascular resistance, and electrolyte balance. However, chronic hepatic injury and resulting splanchnic dilation may disrupt this delicate balance. The role of RAS in liver disease, however, is even more extensive, modulating hepatic fibrosis and portal hypertension. Recognition of an alternative RAS pathway in the past few decades has changed our understanding of RAS in liver disease, and the concept of opposing vs. "rebalanced" forces is an ongoing focus of research. Whether RAS inhibition is beneficial in patients with chronic liver disease appears to be context-dependent, but further study is needed to optimize clinical management and reduce organ-specific morbidity and mortality. This review presents the current understanding of RAS in liver disease, acknowledges areas of uncertainty, and describes potential areas of future investigation.

Evolution of care in cirrhosis: Preventing hepatic decompensation through pharmacotherapy

Cirrhosis is a leading cause of morbidity and mortality, impacting more than 120 million people worldwide. Although geographic differences exist, etiologic factors such as alcohol use disorder, chronic viral hepatitis infections, and non-alcoholic fatty liver disease are prevalent in nearly every region. Historically, significant effort has been devoted to modifying these risks to prevent disease progression. Nevertheless, more than 11% of patients with compensated cirrhosis experience hepatic decompensation each year. This transition signifies the most important prognostic factor in the natural history of the disease, corresponding to a decline in median survival to below 2 years. Over the past decade, the need for pharmacotherapies aimed at reducing the risk for hepatic decompensation has been emphasized, and non-selective beta-blockers have emerged as the most effective option to date. However, a critical therapeutic gap still exists, and additional therapies have been proposed, including statins, rifaximin, and sodium-glucose cotransporter-2 inhibitors. Based on the results of innovative retrospective analyses and small-scale prospective trials, these pharmacotherapies represent promising options, but further studies, including randomized controlled trials, are necessary before they can be incorporated into clinical use. This report highlights the potential impact of these agents and others in preventing hepatic decompensation and discusses how this paradigm shift may pave the way for guideline-directed medical therapy in cirrhosis.

Role of olmesartan in ameliorating diabetic nephropathy in rats by targeting the AGE/PKC, TLR4/P38-MAPK and SIRT-1 autophagic signaling pathways

Diabetic nephropathy (DN) is one of the most serious consequences of diabetes and the most common reason for end-stage renal disease. The current study was set out to investigate the ability of olmesartan medoxomil (OM) to treat DN by evaluating the reno-protective effects of this drug on fat/fructose/streptozotocin (F/Fr/STZ)-induced diabetic rat model. This model was induced by feeding rats high F/Fr diet for 7 weeks followed by injection of a single sub-diabetogenic dose of STZ (35mg/kg; i.p). The F/Fr/STZ-induced diabetic rats were orally treated with either OM (10 mg/kg) or pioglitazone (10 mg/kg); as a standard drug daily for four consecutive weeks. F/Fr/STZ-induced diabetic rats propagated inflammatory, oxidative, and fibrotic events. OM was able to oppose the injurious effects of diabetes; it significantly reduced the elevated levels of advanced glycated end products (AGEs) and downregulated PKC gene expression, therefore, indicating its antioxidant capacity evidenced by mitigation in GSH, MDA renal content. Moreover, OM impaired the inflammatory cascade by suppressing the elevated level of renal TLR4 as well as diminished the inflammatory profibrotic cytokine TGF-β1. Additionally, OM was able to turn off the MAPK cascade mediated by an upsurge in renal angiotensin 1-7 content and decrease the level of renal tubular injury marker, KIM-1. Furthermore, OM enhanced the autophagic activity pathway by upregulating of gene expression of SIRT-1. The histopathological examination confirmed these results. Finally, OM protected against type 2 diabetes-related nephropathy complications by altering inflammatory pathways, oxidative, fibrotic, and autophagic processes triggered by renal glucose overload. This study shows that OM has a reno-protective effect against DN in rats by inhibiting the AGE/PKC, TLR4/P38-MAPK, and SIRT-1 autophagic signaling pathways.

Test-Retest Reliability and Consistency of HVPG and Impact on Trial Design: A Study in 289 Patients from 20 Randomized Controlled Trials

BACKGROUND AND AIMS

Portal hypertension (PH) is a major driver for cirrhosis complications. Portal pressure is estimated in practice by the HVPG. The assessment of HVPG changes has been used for drug development in PH. This study aimed at quantifying the test-retest reliability and consistency of HVPG in the specific context of randomized controlled trials (RCTs) for the treatment of PH in cirrhosis and its impact on power calculations for trial design.

APPROACH AND RESULTS

We conducted a search of published RCTs in patients with cirrhosis reporting individual patient-level data of HVPG at baseline and after an intervention, which included a placebo or an untreated control arm. Baseline and follow-up HVPGs in the control groups were extracted after digitizing the plots. We assessed reliability and consistency and the potential impact of study characteristics. We retrieved a total of 289 before and after HVPG measurements in the placebo/untreated groups from 20 RCTs. The time span between the two HVPG measurements ranged between 20 minutes and 730 days. Pre-/post-HVPG variability was lower in studies including only compensated patients; therefore, modeled sample size calculations for trials in compensated cirrhosis were lower than for decompensated cirrhosis. A higher proportion of alcohol-associated cirrhosis and unicentric trials was associated with lower differences between baseline and follow-up measurements. The smallest detectable difference in an individual was 26% and 30% in compensated and decompensated patients, respectively.

CONCLUSIONS

The test-retest reliability of HVPG is overall excellent. Within-individual variance was higher in studies including higher proportions of decompensated patients. These findings should be taken into account when performing power analysis for trials based on the effects on HVPG or when considering HVPG as a tool to guide therapy of PH.

Primary prevention of variceal bleeding in people with oesophageal varices due to liver cirrhosis: a network meta-analysis

BACKGROUND

Approximately 40% to 95% of people with cirrhosis have oesophageal varices. About 15% to 20% of oesophageal varices bleed in about one to three years. There are several different treatments to prevent bleeding, including: beta-blockers, endoscopic sclerotherapy, and variceal band ligation. However, there is uncertainty surrounding their individual and relative benefits and harms.

OBJECTIVES

To compare the benefits and harms of different treatments for prevention of first variceal bleeding from oesophageal varices in adults with liver cirrhosis through a network meta-analysis and to generate rankings of the different treatments for prevention of first variceal bleeding from oesophageal varices according to their safety and efficacy.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, World Health Organization International Clinical Trials Registry Platform, and trials registers to December 2019 to identify randomised clinical trials in people with cirrhosis and oesophageal varices with no history of bleeding.

SELECTION CRITERIA

We included only randomised clinical trials (irrespective of language, blinding, or status) in adults with cirrhosis and oesophageal varices with no history of bleeding. We excluded randomised clinical trials in which participants had previous bleeding from oesophageal varices and those who had previously undergone liver transplantation or previously received prophylactic treatment for oesophageal varices.

DATA COLLECTION AND ANALYSIS

We performed a network meta-analysis with OpenBUGS using Bayesian methods and calculated the differences in treatments using hazard ratios (HR), odds ratios (OR), and rate ratios with 95% credible intervals (CrI) based on an available-case analysis, according to National Institute for Health and Care Excellence Decision Support Unit guidance. We performed the direct comparisons from randomised clinical trials using the same codes and the same technical details.

MAIN RESULTS

We included 66 randomised clinical trials (6653 participants) in the review. Sixty trials (6212 participants) provided data for one or more comparisons in the review. The trials that provided the information included people with cirrhosis due to varied aetiologies and those at high risk of bleeding from oesophageal varices. The follow-up in the trials that reported outcomes ranged from 6 months to 60 months. All but one of the trials were at high risk of bias. The interventions compared included beta-blockers, no active intervention, variceal band ligation, sclerotherapy, beta-blockers plus variceal band ligation, beta-blockers plus nitrates, nitrates, beta-blockers plus sclerotherapy, and portocaval shunt. Overall, 21.2% of participants who received non-selective beta-blockers ('beta-blockers') - the reference treatment (chosen because this was the most common treatment compared in the trials) - died during 8-month to 60-month follow-up. Based on low-certainty evidence, beta-blockers, variceal band ligation, sclerotherapy, and beta-blockers plus nitrates all had lower mortality versus no active intervention (beta-blockers: HR 0.49, 95% CrI 0.36 to 0.67; direct comparison HR: 0.59, 95% CrI 0.42 to 0.83; 10 trials, 1200 participants; variceal band ligation: HR 0.51, 95% CrI 0.35 to 0.74; direct comparison HR 0.49, 95% CrI 0.12 to 2.14; 3 trials, 355 participants; sclerotherapy: HR 0.66, 95% CrI 0.51 to 0.85; direct comparison HR 0.61, 95% CrI 0.41 to 0.90; 18 trials, 1666 participants; beta-blockers plus nitrates: HR 0.41, 95% CrI 0.20 to 0.85; no direct comparison). No trials reported health-related quality of life. Based on low-certainty evidence, variceal band ligation had a higher number of serious adverse events (number of events) than beta-blockers (rate ratio 10.49, 95% CrI 2.83 to 60.64; 1 trial, 168 participants). Based on low-certainty evidence, beta-blockers plus nitrates had a higher number of 'any adverse events (number of participants)' than beta-blockers alone (OR 3.41, 95% CrI 1.11 to 11.28; 1 trial, 57 participants). Based on low-certainty evidence, adverse events (number of events) were higher in sclerotherapy than in beta-blockers (rate ratio 2.49, 95% CrI 1.53 to 4.22; direct comparison rate ratio 2.47, 95% CrI 1.27 to 5.06; 2 trials, 90 participants), and in beta-blockers plus variceal band ligation than in beta-blockers (direct comparison rate ratio 1.72, 95% CrI 1.08 to 2.76; 1 trial, 140 participants). Based on low-certainty evidence, any variceal bleed was lower in beta-blockers plus variceal band ligation than in beta-blockers (direct comparison HR 0.21, 95% CrI 0.04 to 0.71; 1 trial, 173 participants). Based on low-certainty evidence, any variceal bleed was higher in nitrates than beta-blockers (direct comparison HR 6.40, 95% CrI 1.58 to 47.42; 1 trial, 52 participants). The evidence indicates considerable uncertainty about the effect of the interventions in the remaining comparisons.

AUTHORS' CONCLUSIONS

Based on low-certainty evidence, beta-blockers, variceal band ligation, sclerotherapy, and beta-blockers plus nitrates may decrease mortality compared to no intervention in people with high-risk oesophageal varices in people with cirrhosis and no previous history of bleeding. Based on low-certainty evidence, variceal band ligation may result in a higher number of serious adverse events than beta-blockers. The evidence indicates considerable uncertainty about the effect of beta-blockers versus variceal band ligation on variceal bleeding. The evidence also indicates considerable uncertainty about the effect of the interventions in most of the remaining comparisons.

The Tissue Renin-Angiotensin System and Its Role in the Pathogenesis of Major Human Diseases: Quo Vadis?

Evidence has arisen in recent years suggesting that a tissue renin-angiotensin system (tRAS) is involved in the progression of various human diseases. This system contains two regulatory pathways: a pathological pro-inflammatory pathway containing the Angiotensin Converting Enzyme (ACE)/Angiotensin II (AngII)/Angiotensin II receptor type 1 (AGTR1) axis and a protective anti-inflammatory pathway involving the Angiotensin II receptor type 2 (AGTR2)/ACE2/Ang1–7/MasReceptor axis. Numerous studies reported the positive effects of pathologic tRAS pathway inhibition and protective tRAS pathway stimulation on the treatment of cardiovascular, inflammatory, and autoimmune disease and the progression of neuropathic pain. Cell senescence and aging are known to be related to RAS pathways. Further, this system directly interacts with SARS-CoV 2 and seems to be an important target of interest in the COVID-19 pandemic. This review focuses on the involvement of tRAS in the progression of the mentioned diseases from an interdisciplinary clinical perspective and highlights therapeutic strategies that might be of major clinical importance in the future.

Update on New Aspects of the Renin-Angiotensin System in Hepatic Fibrosis and Portal Hypertension: Implications for Novel Therapeutic Options

There is considerable experimental evidence that the renin angiotensin system (RAS) plays a central role in both hepatic fibrogenesis and portal hypertension. Angiotensin converting enzyme (ACE), a key enzyme of the classical RAS, converts angiotensin I (Ang I) to angiotensin II (Ang II), which acts via the Ang II type 1 receptor (AT1R) to stimulate hepatic fibrosis and increase intrahepatic vascular tone and portal pressure. Inhibitors of the classical RAS, drugs which are widely used in clinical practice in patients with hypertension, have been shown to inhibit liver fibrosis in animal models but their efficacy in human liver disease is yet to be tested in adequately powered clinical trials. Small trials in cirrhotic patients have demonstrated that these drugs may lower portal pressure but produce off-target complications such as systemic hypotension and renal failure. More recently, the alternate RAS, comprising its key enzyme, ACE2, the effector peptide angiotensin-(1–7) (Ang-(1–7)) which mediates its effects via the putative receptor Mas (MasR), has also been implicated in the pathogenesis of liver fibrosis and portal hypertension. This system is activated in both preclinical animal models and human chronic liver disease and it is now well established that the alternate RAS counter-regulates many of the deleterious effects of the ACE-dependent classical RAS. Work from our laboratory has demonstrated that liver-specific ACE2 overexpression reduces hepatic fibrosis and liver perfusion pressure without producing off-target effects. In addition, recent studies suggest that the blockers of the receptors of alternate RAS, such as the MasR and Mas related G protein-coupled receptor type-D (MrgD), increase splanchnic vascular resistance in cirrhotic animals, and thus drugs targeting the alternate RAS may be useful in the treatment of portal hypertension. This review outlines the role of the RAS in liver fibrosis and portal hypertension with a special emphasis on the possible new therapeutic approaches targeting the ACE2-driven alternate RAS.

Pathways of hepatic and renal damage through non-classical activation of the renin-angiotensin system in chronic liver disease

In liver cirrhosis, renin-angiotensin system (RAS) activation sustains renal sodium retention and hepatic fibrogenesis. New information has recently enlivened the traditional concept of RAS. For instance, renin and prorenin bind their ubiquitous receptors, resulting in the local production of angiotensin (Ang) II; increased serum calcium and calcimimetic agents, through stimulation of extracellular calcium-sensing receptors (CaSR), blunt renin production and lead to natriuretic effects in human and experimental cirrhosis. Alongside systemic production, there is Ang II tissue production within various organs through RAS enzymes different from angiotensin-converting enzyme (ACE), that is chymase, tissue plasminogen activator and several cathepsins. In experimental cirrhosis, inhibition of chymase leads to natriuretic and hepatic antifibrotic effects, without changes in systemic haemodynamics. In the kidney, local RAS coordinates proximal and distal tubular sodium reabsorption. However, renalase, whose plasma and tissue levels are severely altered in experimental cirrhosis, degrades systemic and renal tubule catecholamines, antagonizing the effects of renal RAS. Angiotensinogen-derived natriuretic and vasodilating peptides (Ang1-9, Ang1-7, Ang3-8) and their receptors have been described. Receptor agonists or antagonists are available to affect portal hypertension and sodium retention in cirrhosis. ACE2-dependent generation of Ang1-7 may inhibit experimental liver fibrosis. inhibition of Ang1-7 clearance by means of neprilysin blockade has portal hypotensive and natriuretic effects. Ang1-12, whose production renin does not regulate, is converted to several different angiotensin peptides via chymase. Finally, Ang II behaves as either an antinatriuretic or a natriuretic agent, based on the tissue content of AT₁ R and AT₂ R receptors, their ratio being prone to pharmacological modulation.

Future Pharmacological Therapies of Portal Hypertension

PURPOSE OF REVIEW

To provide an overview of recent pharmacological treatments for portal hypertension evaluated in early clinical trials, with particular emphasis on the pathophysiological basis of their use.

RECENT FINDINGS

In patients with compensated cirrhosis, even small decreases in portal pressure (as small as 1 mmHg) are associated with a lower probability of decompensation. In patients with decompensated cirrhosis, portal pressure "response" to non-selective beta-blocker (NSBB) therapy is associated with a lower mortality. When present, significant portal hypertension persists even after elimination of the etiology of cirrhosis and this justifies the continued development of new drugs that target portal hypertension.

SUMMARY

Over several decades we have gained great depth in the understanding of portal hypertension, its mechanisms and complications. NSBBs, which act by reducing portal venous inflow (an extrahepatic target), are effective in reducing portal pressure and have been the mainstay of therapy for portal hypertension in the last 35 years -being effective in preventing decompensation and variceal hemorrhage. However, because not all patients will have a sufficient response to NSBB and some may be intolerant to NSBB, alternative drugs or drugs that will augment the effect of NSBB on portal pressure are being tested in pre-clinical and early-clinical trials. Many of these drugs target more than one of the intrahepatic or extrahepatic mechanisms implicated in the pathogenesis of portal hypertension in cirrhosis. Out of these proposed therapies, statins have emerged as the most promising new pharmacological therapy for the treatment of portal hypertension.

Angiotensin II receptor blockers for the treatment of portal hypertension in patients with liver cirrhosis: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Randomized controlled trials (RCTs) showed inconsistent results regarding the efficacy of angiotensin II receptor blockers (ARBs) on portal pressure as indicated by hepatic venous pressure gradient (HVPG).

METHODS

A meta-analysis of RCTs was performed to evaluate the influence of ARBs treatment on HVPG. PubMed, Embase, and Cochrane's Library were searched for relevant RCTs. A fixed or a randomized effect model was used to pool the results according the heterogeneity. Subgroup analyses were performed to explore the source of heterogeneity.

RESULTS

Eleven RCTs with 394 patients were included. ARBs treatment did not significantly change HVPG as compared with controls (weighted mean difference [WMD] = -0.63, 95% confidence interval [CI] -1.73 to 0.47 mmHg, p = 0.26; I2 = 60%). These results were consistent in studies comparing ARBs with propranolol (WMD = -0.40, 95% CI -2.22 to 1.41 mmHg, p = 0.67; I2 = 68%), and those comparing ARBs with non-active controls including placebo or no treatment (WMD = -1.05, 95% CI -2.33 to 0.24 mmHg, p = 0.13; I2 = 44%). These results were also not affected by the individual ARBs used. Moreover, treatment of ARBs significantly reduced mean arterial blood pressure (WMD = -6.12, 95% CI -9.69 to -2.55 mmHg, p = 0.008; I2 = 53%), and the risk of symptomatic hypotension was increased (RR = 4.13, 95% CI 0.94 to 18.18, p = 0.06; I2 = 0%).

CONCLUSIONS

ARBs did not reduce portal pressure in patients with cirrhosis; moreover, the risk of symptomatic hypotension may increase.

Future Pharmacotherapy for Non-alcoholic Steatohepatitis (NASH): Review of Phase 2 and 3 Trials

Non-alcoholic steatohepatitis (NASH) results from inflammation and hepatocyte injury in the setting of hepatic steatosis. Non-alcoholic steatohepatitis increases the risk of progression to liver fibrosis and cirrhosis, and is the most rapidly growing etiology for liver failure and indication for liver transplantation in the USA. Weight loss and lifestyle modification remain the standard first-line treatment, as no USA Food and Drug Administration-approved pharmacotherapy currently exists. The past decade has seen an explosion of interest in drug development targeting pathologic pathways in non-alcoholic steatohepatitis, with numerous phase 2 and 3 trials currently in progress. Here, we concisely review the major targets and mechanisms of action by class, summarize results from completed pivotal phase 2 studies, and provide a detailed outline of key active studies with trial data for drugs in development, including obeticholic acid, elafibranor, cenicriviroc and selonsertib.

The potential therapeutic use of renin-angiotensin system inhibitors in the treatment of inflammatory diseases

Inflammation is a normal part of the immune response to injury or infection but its dysregulation promotes the development of inflammatory diseases, which cause considerable human suffering. Nonsteroidal anti-inflammatory agents are the most commonly prescribed agents for the treatment of inflammatory diseases, but they are accompanied by a broad range of side effects, including gastrointestinal and cardiovascular events. The renin-angiotensin system (RAS) is traditionally known for its role in blood pressure regulation. However, there is increasing evidence that RAS signaling is also involved in the inflammatory response associated with several disease states. Angiotensin II increases blood pressure by binding to angiotensin type 1 (AT₁ ) receptor, and direct renin inhibitors, angiotensin-converting enzyme (ACE) inhibitors and AT₁ receptor blockers (ARBs) are clinically used as antihypertensive agents. Recent data suggest that these drugs also have anti-inflammatory effects. Therefore, this review summarizes these recent findings for the efficacy of two of the most widely used antihypertensive drug classes, ACE inhibitors and ARBs, to reduce or treat inflammatory diseases such as atherosclerosis, arthritis, steatohepatitis, colitis, pancreatitis, and nephritis.

Compound Astragalus and Salvia miltiorrhiza extract inhibits hepatocarcinogenesis via modulating TGF-β/TβR and Imp7/8

Compound Astragalus and Salvia miltiorrhiza extract (CASE) is a Chinese herbal formula consisting of astragalosides, astragalus polysaccharide and salvianolic acids extracted from Astragalus membranaceus and Salvia miltiorhiza. Previous studies by our group have demonstrated that CASE effectively suppresses diethylinitrosamine (DEN)-induced hepatocellular carcinoma (HCC) in rats via modulating transforming growth factor β/Mothers against decapentaplegic (TGFβ/Smad) signaling. To further elucidate the mechanism of CASE, the effects of CASE on TGF-β₁, the serine/threonine kinase receptors of TGF-β [TGF-β receptor type-I (TβRI) and TβRII] and karyopherins [Importin 7 (Imp7) and Imp8], which are crucial for TGF-β/Smad signaling in fibro-hepatocarcinogenesis, were assessed in the present study using in vivo (DEN-induced HCC in rats) and in vitro [TGF-β₁-stimulated rat myofibroblasts (MFBs) and HepG2 cells] models of fibro-hepatocarcinogenesis. Hematoxylin and eosin staining revealed that CASE may suppress inflammatory reactions and fibrosis in HCC as well as increasing the differentiation of HCC cells. Positive TGF-β₁ staining was increased in HCC nodule areas and in adjacent normal liver tissues in DEN-treated rats, while TβRI staining was increased only in normal adjacent liver tissues. The elevated expression of TGF-β₁, TβRI and TβRII was suppressed by CASE. CASE treatment also reduced glutathione S-transferase P 1 and Imp7/8 protein expression in fibro-hepatocarcinogenesis. In vitro experiments confirmed that CASE was able to decrease the expression of TβRI and TβRII in TGF-β₁-stimulated MFBs and HepG2 cells. These results indicate that the anti-HCC effect of CASE may be achieved by mediating TGF-β/TβR and Imp7/8 protein expression, suggesting that CASE has multiple targets in HCC treatment.

Therapeutic effect of renin angiotensin system inhibitors on liver fibrosis

Background and objective:

Currently, there is no effective therapy available for liver fibrosis. This study aims to evaluate the efficacy of renin angiotensin system inhibitors on liver fibrosis.

Method:

Full-text randomized controlled trials in patients with liver fibrosis were identified and included in the meta-analysis. The primary outcome measure was the histological fibrosis score of the liver. Secondary outcome measures included fibrosis area of the liver, serological levels of fibrosis markers, adverse events, and withdrawals.

Results:

From 6973 non-duplicated entries by systematic search, four randomized controlled trials with 210 patients were identified. The renin angiotensin system inhibitors therapy resulted in a marginally significant reduction in liver fibrosis score (MD = -0.30; 95% CI: -0.62–0.02, p = 0.05) and a significant reduction in liver fibrosis area (MD = -2.36%; 95% CI: -4.22%–-0.50%, p = 0.01) as compared with control. The therapy was well tolerated and there was no significant difference in withdrawals between treatment and control groups (RD = 0.00; 95% CI: -0.06–0.06, p = 0.97).

Conclusions:

Renin angiotensin system inhibitor therapy results in a reduction in liver fibrosis score and liver fibrosis area in patients with hepatic fibrosis with good safety profile. However, randomized controlled trials of high-quality will clarify the effectiveness of renin angiotensin system inhibitors on liver fibrosis.

MAPK inhibitors modulate Smad2/3/4 complex cyto-nuclear translocation in myofibroblasts via Imp7/8 mediation

Mitogen-activated protein kinase (MAPK) pathway-dependent linker phosphorylation of Smad2/3 and subsequent formation of Smad2/3/4 complex and its nuclear translocation are crucial for dysregulated transforming growth factor beta (TGF)-β/Smad signaling in liver fibrosis. Abrogation of this critical step of TGF-β/Smad signaling leading to liver fibrosis could provide new insights for future therapy, but the mechanisms remain incompletely understood. In pursuit, we investigated the subcellular expression and nuclear trafficking of the rate limiting Smad2/3/4 complex in exogenous TGF-β1-stimulated myofibroblasts (MFBs) using three MAPK-specific inhibitors. Our results showed that exogenous TGF-β1 stimulation of MFBs produced both increased protein expression and nuclear translocation of phosphorylated (p)-Smad2C/L, oncogenic pSmad3L, Smad4, importin7/8 (Imp7/8), and plasminogen activator inhibitor (PAI)-1 (Protein and mRNA), while decreased Smad7 protein expression. However, the MAPK-specific inhibitors differentially reversed these observations; for instance, ERK-specific inhibitor blocked the expression and nuclear translocation of pSmad2C/L, while both JNK and p38-specific inhibitors blocked the expression and nuclear translocation of pSmad2C/L and oncogenic pSmad3L. The MAPK-specific inhibitors had no significant effect on the total protein expression of Smad4, but rather significantly blocked its nuclear translocation. All the MAPK-specific inhibitors restored Smad7 expression and also decreased Imp7/8 and PAI-1 (Protein and mRNA) expression. Evidently, the MAPK-specific inhibitors blocked Smad2/3/4 complex formation via restoration of inhibitory Smad7 expression and blockade of Smad3L phosphorylation, while they blocked nuclear translocation of Smad2/3/4 complex through inhibition of Imp7/8 leading to decreased PAI-1 (Protein and mRNA) expression.

Preoperative administration of polysaccharide Kureha and reduced plasma transforming growth factor-β in patients with advanced gastric cancer: A randomized clinical trial

Systemic abrogation of TGF-β signaling results in tumor reduction through cytotoxic T lymphocytes activity in a mouse model. The administration of polysaccharide-Kureha (PSK) into tumor-bearing mice also showed tumor regression with reduced TGF-β. However, there have been no studies regarding the PSK administration to cancer patients and the association with plasma TGF-β. PSK (3 g/day) was administered as a neoadjuvant therapy for 2 weeks before surgery. In total, 31 advanced gastric cancer (AGC) patients were randomly assigned to group A (no neoadjuvant PSK; n=14) or B (neoadjuvant PSK therapy; n=17). Plasma TGF-β was measured pre- and postoperatively. The allocation factors were clinical stage (cStage) and gender. Plasma TGF-β ranged from 1.85-43.5 ng/ml (average, 9.50 ng/ml) in AGC, and 12 patients (38.7%) had a high value, >7.0 ng/ml. These patients were largely composed of poorly-differentiated adenocarcinoma with pathological stage III/IV. All the six elevated cases in group B showed a significant reduction of plasma TGF-β (from 21.6 to 4.5 ng/ml, on average), whereas this was not exhibited in group A. The cases within the normal limits of TGF-β remained unchanged irrespective of PSK treatment. Analysis of variance showed a statistically significant reduction in the difference of plasma TGF-β between groups A and B (P=0.019). PSK reduced the plasma TGF-β in AGC patients when the levels were initially high. The clinical advantage of PSK may, however, be restricted to specific histological types of AGC. Perioperative suppression of TGF-β by PSK may antagonize cancer immune evasion and improve patient prognosis in cases of AGC.

TGF-β signal shifting between tumor suppression and fibro-carcinogenesis in human chronic liver diseases

Perturbation of transforming growth factor (TGF)-β signaling in hepatocytes persistently infected with hepatitis viruses promotes both fibrogenesis and carcinogenesis (fibro-carcinogenesis). Insights into hepatocytic fibro-carcinogenesis have emerged from recent detailed analyses of context-dependent and cell type-specific TGF-β signaling processes directed by multiple phosphorylated forms (phospho-isoforms) of Smad mediators. In the course of hepatitis virus-related chronic liver diseases, chronic inflammation, ongoing viral infection, and host genetic/epigenetic alterations additively shift hepatocytic Smad phospho-isoform signaling from tumor suppression to fibro-carcinogenesis, accelerating liver fibrosis and increasing risk of hepatocellular carcinoma (HCC). After successful antiviral therapy, patients with chronic hepatitis can experience less risk of HCC occurrence by reversing Smad phospho-isoform signaling from fibro-carcinogenesis to tumor suppression. However, patients with cirrhosis can still develop HCC owing to sustained, intense fibro-carcinogenic signaling. Recent progress in understanding Smad phospho-isoform signaling should permit use of Smad phosphorylation as a tool predicting the likelihood of liver disease progression, and as a biomarker for assessing the effectiveness of interventions aimed at reducing fibrosis and cancer risk.

Therapeutic potential of microRNA: a new target to treat intrahepatic portal hypertension?

Intrahepatic portal hypertension accounts for most of the morbidity and mortality encountered in patients with liver cirrhosis, due to increased portal inflow and intrahepatic vascular resistance. Most treatments have focused only on portal inflow or vascular resistance. However, miRNA multitarget regulation therapy may potentially intervene in these two processes for therapeutic benefit in cirrhosis and portal hypertension. This review presents an overview of the most recent knowledge of and future possibilities for the use of miRNA therapy. The benefits of this therapeutic modality--which is poorly applied in the clinical setting--are still uncertain. Increasing the knowledge and current understanding of the roles of miRNAs in the development of intrahepatic portal hypertension and hepatic stellate cells (HSCs) functions, as well as their potential as novel drug targets, is critical.

Valsartan improves portal hypertensive gastropathy in rats possibly via TGF-β1/Smad signaling pathway

AIM: To investigate the efficacy and mechanisms of action of valsartan on portal hypertensive gastropathy in rats with gastric mucosa lesions.

METHODS: Forty-eight SD rats were randomly divided into a sham-operated group, a portal hypertension gastropathy group, a valsartan prevention group, a normal dose valsartan group and a high dose valsartan group. Portal hypertensive gastropathy was induced by the partial portal vein ligation method. Gastric mucosa TGF-beta1 expression and microvessel density (MVD) were detected by immunohistochemical staining method. Gastric mucosa Smad2 and Smad7 protein expression was detected by Western blot. Plasma levels of rennin activity (PRA), angiotensin II (Ang II), alanine aminotransferase (ALT), and albumin (ALB) were determined by ELISA.

RESULTS: Compared with the model group, gastric mucosa TGF-β1 (11.58 ± 2.27, 13.29 ± 2.82, 13.15 ± 3.36 vs 24.25 ± 3.48, all P <0.05) and Smad2 (0.86 ± 0.59, 0.82±0.36, 0.83 ± 0.49 vs 1.60 ± 0.77, P < 0.05) protein expression was significantly decreased in the valsartan prevention group, normal dose valsartan group and high dose valsartan group. Smad7 protein expression in the valsartan prevention group, normal dose valsartan group and high dose valsartan group was significantly higher than that in the model group (1.59 ± 0.72, 1.65 ± 0.80, 1.69 ± 0.85 vs 0.58 ± 0.35, all P < 0.05). Plasma PRA (16.49 ng/mL ± 2.77 ng/mL, 15.92 ng/mL ± 4.30 ng/mL, 16.72 ng/mL ± 5.48 ng/mL vs 11.49 ng/mL ± 2.12 ng/mL, all P <0.05) and Ang II (1664.44 pg/mL ± 285.47 pg/mL, 1686.82 pg/mL ± 499.16 pg/mL, 1734.07 pg/mL ± 326.66 pg/mL vs 1110.38 pg/mL ± 193.85 pg/mL, all P <0.01) were also significantly higher in the valsartan prevention group, normal dose valsartan group and high dose valsartan group than in the model group.

CONCLUSION: Valsartan can improve portal hypertensive gastropathy probably by down-regulating TGF-β1 and Smad2 expression and up-regulating Smad7 expression.

p38 MAPK-mediated proliferation-promoting effect of angiotensin Ⅱ on hepatic stellate cells

AIM: To elucidate the signal transduction mechanism by which angiotensin Ⅱ promotes the proliferation of hepatic stellate cells (HSCs).

METHODS: The influence of angiotensin Ⅱ on p38 MAPK expression in primarily cultured HSCs was detected by Western blot. The p38 MAPK inhibitor SB203580 was incubated with HSCs to observe its effect on angiotensin Ⅱ-induced transforming growth factor-β (TGF-β) secretion and collagen Ⅰ and Ⅳ expression.

RESULTS: Western blot analysis showed that, compared to the normal saline group, treatment with angiotensin Ⅱ (10^-8, 10^-7, 10^-6 moL/L) for 24 h significantly induced p38 MAPK expression (0.45 ± 0.052, 0.61 ± 0.026, 0.87 ± 0.032 vs 0.27 ± 0.020, all P < 0.0005). Compared to the normal saline group, treatment with angiotensin Ⅱ (10^-6 moL/L) for 24 h significantly induced HSC proliferation (0.1073 ± 0.0093 vs 0.5233 ± 0.0240, P < 0.0005), promoted incretion of TGF-β1 (10.6 ng/mL ± 0.98 ng/mL vs 100.8 ng/mL ± 3.67 ng/mL, P < 0.0005), and increased the expression of collagen α1(Ⅰ) and α1(Ⅳ) (1.13 ± 0.053 vs3.74 ± 0.047; 1.35 ± 0.035 vs 4.07 ± 0.072; both P < 0.0005). Pre-treatment with SB203580 significantly attenuated the effect of angiotensin Ⅱ on the above parameters in HSCs (0.2033 ± 0.0176 vs 0.5233 ± 0.0240; 21.07 ng/mL ± 2.08 ng/mL vs 100.8 ng/mL ± 3.67 ng/mL; 1.16 ± 0.024 vs 3.74 ± 0.047; 1.56 ± 0.075 vs 4.07 ± 0.072, all P < 0.0005).

CONCLUSION: Angiotensin Ⅱ induces HSC proliferation and increases expression of TGF-β1 via the p38 MAPK pathway.