Attenuation of hepatic fibrosis through captopril and enalapril in the livers of bile duct ligated rats

Repurposing of Angiotensin-converting-enzyme Inhibitor on Prevention of Post-surgical Tendon Adhesion

BACKGROUND

Formation of adhesion bands is a frequent clinical complication after tendon injury or surgery with limited treatment options. This study investigates the repurposing of Angiotensin-Converting-Enzyme Inhibitor (ACEI) in attenuating post-operative tendon-sheath adhesion bands in an Achilles tendon rat model.

METHODS

Structural, mechanical, histological, and biochemical characteristics of the Achilles tendons were compared in the presence and absence of oral ACEI (enalapril) using the Achilles tendon adhesion (TA) model in rats. Inflammation and total fibrosis of tendon tissues were compared between groups using molecular investigations along with macroscopic and histological scoring methods.

RESULTS

ACEI significantly alleviated the severity, length, and density of Achilles TAs. Moreover, histopathological changes, recruitment of inflammatory cells, and inflammation were significantly decreased in post-operative tissue samples as quantified with the Moran scoring model. We showed that ACEI treatment elicits a potent anti-fibrotic effect on tendon tissue samples, as illustrated by decreasing the severity and extent of the formed fibrotic tissue and collagen accumulation at the site of surgery when scored either by Tang or Ishiyama grading systems. The H&E staining showed no histopathological changes or damage to the principal organs.

CONCLUSION

Our results showed that ACEI is a safe and effective therapeutic candidate with potent immunomodulatory and anti-fibrotic features to alleviate surgery-induced development of fibrotic adhesive tissue. However, its efficacy needs to be further validated in clinical studies.

Effect of angiotensin II pathway inhibitors on post-surgical adhesion band formation: a potential repurposing of old drugs

BACKGROUND

In this study we investigated the therapeutic potential of angiotensin II pathway inhibitors in attenuating post-surgical adhesion band formation in tendon injury.

METHOD

We assigned 30 Wistar albino rats to 5 groups, including negative control, positive control, sham, Telmisartan- and Enalapril-treated groups (n=6). Telmisartan and Enalapril at a dose of 10 mg/kg were administered intraperitoneally for 21 days. Hematoxylin-Eosin, and Masson's trichrome staining were used to measure the inflammatory cell accumulation and collagen deposition in the Achilles tendon tissue sections. Oxidative stress markers were analyzed in tissue samples by spectrophotometric methods. Properties of Achilles tendon adhesions were compared based on Tang and Ishiyama scoring systems in the presence and absence of angiotensin II pathway inhibitors.

RESULTS

Telmisartan and Enalapril reduced severity, length, and density of surgical-induced tendon adhesion at site of injury (***p < 0.001). Our results showed that administration of angiotensin II pathway inhibitors decreased infiltration of inflammatory cells to the injured area (*p < 0.05) and suppressed inflammation by regulating oxidative stress markers including MDA (***p < 0.001), total thiol (***p < 0.001), CAT (***p < 0.001), and SOD (***p < 0.001), in post-operative Achilles tendon tissues. Significant lower collagen deposition and formation of fibrotic tissues was seen in Telmisartan- and Enalapril-treated groups as detected by Masson's trichrome staining which correlated with a decrease in quantity (**p < 0.01) and grading of fibrosis score (***p < 0.001), in adhesive tissues. Moreover, inhibition of angiotensin II pathway could also ameliorate mechanical properties including ultimate load (***p < 0.001), and ultimate stress (*p < 0.05) in injured Tendons.

CONCLUSION

Our results showed that ssuppression of inflammation and fibrosis are two mechanisms by which Telmisartan and Enalapril elicit potent protective responses post Achilles tendon injuries.

Promising results of captopril in improving knee arthrofibrosis and cartilage status: an animal model study

PURPOSE

Several cytokines and growth factors start and progress the destruction process of joint hyaline cartilage and fibrosis formation. Captopril is classified as an Angiotensin-converting enzyme inhibitor in which several studies revealed that captopril significantly decreases fibrosis formation in some organs like the liver, heart, and kidney. This study aimed to evaluate the use of captopril in reducing the possibility of arthrofibrosis and osteoarthritis in an animal model.

METHOD

In this in-vivo animal model study, the anterior cruciate ligament of 24 rabbits was transected to induce osteoarthritis and arthrofibrosis. The control group contained 11 rabbits and the second group consisted of 13 rabbits. The second group was treated with 10 mg/ kilogram/day captopril through a nasogastric tube. The control group was treated with normal saline in the same way. Cartilage damage and osteoarthritis were evaluated by Osteoarthritis Research Society International (OARSI) scoring system. After 30 days, animals were sacrificed, and arthrofibrosis and cartilage damage were evaluated microscopically and macroscopically.

RESULTS

According to macroscopic and microscopic evaluation, captopril dramatically reduced arthrofibrosis formation based on visual scoring and the Masson trichrome staining system. Cartilage damage was lower in the intervention group compared to the control group.

CONCLUSIONS

Captopril is an angiotensin-converting enzyme inhibitor that demonstrated to significantly decreases the possibility of arthrofibrosis. Although the beneficial preventive effect of captopril on osteoarthritis was not proved statistically, better results may be obtained if the route of administration or drug dosage is changed.

Captopril suppresses hepatic mammalian target of rapamycin cell signaling and biomarkers of inflammation and oxidative stress in thioacetamide-induced hepatotoxicity in rats

BACKGROUND

The potential inhibitory effects of captopril, the angiotensin-converting enzyme inhibitor, on thioacetamide (TAA)-induced hepatic mammalian target of rapamycin (mTOR), liver injury enzymes, blood pressure, and biomarkers of inflammation and oxidative stress have not been investigated before.

MATERIALS AND METHODS

Rats were either injected with TAA (200 mg/kg; twice a week for 8 weeks) before being sacrificed after 10 weeks (model group) or were pretreated with captopril (150 mg/kg) daily for two weeks prior to TAA injections and continued receiving both agents until the end of the experiment (protective group).

RESULTS

Captopril significantly (p < .05) inhibited TAA-induced hypertension, liver tissue levels of mTOR, TIMP-1, TNF-α, IL-6, MDA; and blood levels of lipids, ALT, and AST. We further demonstrated a significant (p < .01) positive correlation between mTOR scoring and the levels of inflammatory, oxidative and liver injury biomarkers.

CONCLUSIONS

Captopril protects against TAA-induced mTOR, liver injury enzymes, dyslipidemia, hypertension, inflammation, and oxidative stress.

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.

The comparative efficacy of renin-angiotensin system blockers in schistosomal hepatic fibrosis

Schistosomiasis mansoni is involved in hepatic fibrogenesis and portal hypertension. Previous studies proved that blockade of some components of the renin-angiotensin system (RAS) reduce liver fibrogenesis. However, the effects of inhibition of early stages of RAS pathway in schistosomal fibrosis have not been studied yet. Thus, the aim of this study was to compare the role of different antihypertensive drugs on hepatic fibrosis in murine schistosomiasis. BALB/c mice (n = 50) weighing 20g were subjected to inoculation of 50 cercariae and submitted to different treatments: aliskiren, 50 mg/kg (n = 10); bradykinin, 2 μg/kg (n = 5); losartan, 10 mg/kg (n = 10); lisinopril 10 mg/kg (n = 5) and control, proportional volume vehicle (n = 5); daily for 14 weeks. Six animals were not subjected to cercariae inoculation or any type of treatment. Ultrasound, histological, immunohistochemical and proteomic analyzes were performed to evaluate markers associated with hepatic fibrogenesis. The hepatic areas stained with Sirius red and thenumber of cells marked by α-SMA in animals treated with aliskiren, bradykinin, lisinopril and losartan were diminished when compared to control group, demonstrating reduced hepatic fibrosis after RAS blockade. These results were reinforced by ultrasonography analysis and protein expression of TGFβ. These findings demonstrated the effect of RAS inhibition on hepatic fibrosis in murine schistosomiasis, with the most evident results being observed in the losartan and aliskiren treated groups. The main mechanisms underlying this process appear to involve anti-fibrogenic activity through the inhibition of collagen and TGFβ synthesis.

Mechanotransduction-modulated fibrotic microniches reveal the contribution of angiogenesis in liver fibrosis

The role of pathological angiogenesis on liver fibrogenesis is still unknown. Here, we developed fibrotic microniches (FμNs) that recapitulate the interaction of liver sinusoid endothelial cells (LSECs) and hepatic stellate cells (HSCs). We investigated how the mechanical properties of their substrates affect the formation of capillary-like structures and how they relate to the progression of angiogenesis during liver fibrosis. Differences in cell response in the FμNs were synonymous of the early and late stages of liver fibrosis. The stiffness of the early-stage FμNs was significantly elevated due to condensation of collagen fibrils induced by angiogenesis, and led to activation of HSCs by LSECs. We utilized these FμNs to understand the response to anti-angiogenic drugs, and it was evident that these drugs were effective only for early-stage liver fibrosis in vitro and in an in vivo mouse model of liver fibrosis. Late-stage liver fibrosis was not reversed following treatment with anti-angiogenic drugs but rather with inhibitors of collagen condensation. Our work reveals stage-specific angiogenesis-induced liver fibrogenesis via a previously unrevealed mechanotransduction mechanism which may offer precise intervention strategies targeting stage-specific disease progression.

Effect of Renin-Angiotensin System Blockage in Patients with Acute Respiratory Distress Syndrome: A Retrospective Case Control Study

Background

Acute respiratory distress syndrome (ARDS) remains a life-threatening disease. Many patients with ARDS do not recover fully, and progress to terminal lung fibrosis. Angiotensin-converting enzyme (ACE) inhibitor is known to modulate the neurohormonal system to reduce inflammation and to prevent tissue fibrosis. However, the role of ACE inhibitor in the lungs is not well understood. We therefore conducted this study to elucidate the effect of renin-angiotensin system (RAS) blockage on the prognosis of patients with ARDS.

Methods

We analyzed medical records of patients who were admitted to the medical intensive care unit (ICU) at a tertiary care hospital from January 2005 to December 2010. ARDS was determined using the Berlin definition. The primary outcome was the mortality rate of ICU. Survival analysis was performed after adjustment using propensity score matching.

Results

A total of 182 patients were included in the study. Thirty-seven patients (20.3%) took ACE inhibitor or angiotensin receptor blocker (ARB) during ICU admission, and 145 (79.7%) did not; both groups showed similar severity scores. In the ICU, mortality was 45.9% in the RAS inhibitor group and 58.6% in the non-RAS inhibitor group (P = 0.166). The RAS inhibitor group required a longer duration of mechanical ventilation (29.5 vs. 19.5, P = 0.013) and longer ICU stay (32.1 vs. 20.2 days, P < 0.001). In survival analysis, the RAS inhibitor group showed better survival rates than the non-RAS group (P < 0.001).

Conclusions

ACE inhibitor or ARB may have beneficial effect on ARDS patients.

Active immunization against transforming growth factor beta1 prevents hepatic fibrosis in a rat model of liver disease

Transforming growth factor beta1 (TGF-β1) plays an important role in hepatic fibrogenesis. In this study, we documented the effects of active immunization against TGF-β1 on hepatic fibrosis in an animal model of chronic liver disease. BALB/c mice were immunized against 3 different peptides of TGF-β1 ligated into hepatitis B virus core protein (HBVc). Titers of TGF-β1 antibodies were documented by enzyme linked immunoassays and antibody activity by cell membrane receptor binding and proliferation assays. The most immunogenic recombinant HBVc + TGF-β1 peptide (HBVc + C) then served as a vaccine in Sprague-Dawley rats with dimethylnitrosamine-induced chronic liver disease. Hepatic fibrosis was documented by serum hyaluronic acid levels, liver histology, and reverse transcriptase polymerase chain reaction for hepatic collagen I (α1) and smooth muscle alpha actin mRNA expression. Relative to control rats vaccinated with HBVc alone, recombinant HBVc + C vaccinated animals had significantly lower serum hyaluronic acid levels, less histologic evidence of hepatic fibrosis, and reduced expression of collagen I (α1) and smooth muscle alpha actin mRNA in the liver. The results of this proof-of-concept study suggest that active immunization against TGF-β1 is a worthwhile strategy to pursue in efforts to prevent hepatic fibrosis associated with chronic liver disease.

Antifibrotic effect of AT-1 blocker and statin in rats with hepatic fibrosis

Hepatic fibrosis is an outcome of chronic liver injury. Angiotensin II (ANG II) may play a role in the pathogenesis of hepatic fibrosis. Certain drugs such as ACE inhibitors, ANG II antagonists, and even statins could interfere with the renin angiotensin system and modulate its deleterious effects. This study was carried out to investigate the possible role of losartan and atorvastatin in liver fibrosis. Liver fibrosis was induced in rats by i.p. injection of 50% CCl₄ twice per week for 8 weeks. The rats intoxicated with CCl₄ were divided into four groups: fibrosis control; losartan group; atorvastatin group; and co-treated group. A fifth group of normal healthy rats served as a control group. The results showed that losartan and atorvastatin, either alone or in combination, significantly decreased ALT, AST, hyaluronic acid and hydroxyproline levels in their groups compared to those of the fibrosis control group. A significant decrease in TGF-β was found in the losartan and co-treated groups but not in the atorvastatin group. These biochemical data were supported by liver histopathology and α-SMA. The results indicate that the combined treatment with both losartan and atorvastatin produced a greater effect than either drug alone and proved a beneficial role in inhibiting or reversing liver fibrosis.

Telmisartan attenuates hepatic fibrosis in bile duct-ligated rats

AIM

To evaluate the antifibrotic effect of telmisartan, an angiotensin II receptor blocker, in bile duct-ligated rats.

METHODS

Adult Sprague-Dawley rats were allocated to 3 groups: sham-operated rats, model rats underwent common bile duct ligation (BDL), and BDL rats treated with telmisartan (8 mg/kg, po, for 4 weeks). The animals were sacrificed on d 29, and liver histology was examined, the Knodell and Ishak scores were assigned, and the expression of angiotensin-converting enzyme (ACE) and ACE2 was evaluated with immunohistochemical staining. The mRNAs and proteins associated with liver fibrosis were evaluated using RTQ-PCR and Western blot, respectively.

RESULTS

The mean fibrosis score of BDL rats treated with telmisartan was significantly lower than that of the model rats (1.66±0.87 vs 2.13±0.35, P=0.015). However, there was no significant difference in inflammation between the two groups, both of which showed moderate inflammation. Histologically, treatment with telmisartan significantly ameliorated BDL-caused the hepatic fibrosis. Treatment with telmisartan significantly upregulated the mRNA levels of ACE2 and MAS, and decreased the mRNA levels of ACE, angiotensin II type 1 receptor (AT1-R), collagen type III, and transforming growth factor β1 (TGF-β1). Moreover, treatment with telmisartan significantly increased the expression levels of ACE2 and MAS proteins, and inhibited the expression levels of ACE and AT1-R protein.

CONCLUSION

Telmisartan attenuates liver fibrosis in bile duct-ligated rats via increasing ACE2 expression level.

Attenuation of hepatic fibrosis through ultrasound-microbubble-mediated HGF gene transfer in rats

OBJECTIVE

The objective was to explore the feasibility of ultrasound-microbubble-mediated hepatocyte growth factor (HGF) gene transfer for treating rat hepatic fibrosis induced by CCl(4).

METHODS

Forty-eight male SD rats were divided into ultrasound-microbubble-HGF group (U-M-HGF group), ultrasound-HGF group (U-HGF group), microbubble-HGF group (M-HGF group), HGF group (HGF group), CCl(4) group (control group), and normal group. The serum levels of alanine transaminase (ALT), aspartate transaminase (AST), total protein, albumin (ALB), and globulin (GLB) and the ratio of ALB/GLB were determined after treatment. The degree of hepatic fibrosis was evaluated by histopathological numerical scores. The protein expressions of HGF, collagen I, collagen III, and α-smooth muscle antibody (α-SMA) were detected by immunohistochemistry.

RESULTS

Ultrasound-microbubble-mediated HGF therapy significantly reduced the serum level of ALT and AST to 59.88% and 49.18% of the control group, respectively. Ultrasound-microbubble-mediated HGF therapy prevented liver fibrosis, with an obvious decrease in fibrosis areas and extracellular matrix production of collagen I, collagen III, and α-SMA. The gene therapy could induce HGF delivery into the fibrotic liver effectively.

CONCLUSIONS

Ultrasound-microbubble-mediated HGF gene therapy can reduce liver fibrosis, which provides a novel strategy for gene therapy of chronic liver disease.

β-Adrenoceptor blockade in sclerosing cholangitis of Mdr2 knockout mice: antifibrotic effects in a model of nonsinusoidal fibrosis

Primary sclerosing cholangitis (PSC) is a cholestatic liver disease with high propensity to develop into cholangiocarcinoma. The hepatobiliary disorder of PSC is due to progressive fibrosis surrounding the intra- and extrahepatic bile ducts. Until now, no effective medical therapy exists. To study the progression of sclerosing cholangitis after inhibition of the sympathetic nervous system by blockade of the β-adrenoceptors, we used the Mdr2(-/-) mouse model, which develops periportal fibrosis similar to human PSC. Liver tissues of Mdr2(-/-) mice untreated or treated with the β-adrenoceptor antagonist propranolol were analyzed for inflammation and fibrosis progression at different time points by histological scoring and immunostaining for α-smooth muscle actin (α-SMA), CD45 and S100A4. Transaminases and hydroxyproline contents were determined. Expression of angiotensinogen, endothelin-1, TGF-β, TNF-α, CTGF and procollagen 1A1 was studied by real-time PCR on laser-microdissected areas of acinar zones I and II-III. After 3 months, periportal fibrosis had developed in Mdr2(-/-) mice, but immunostaining revealed no sinusoidal and only minor periportal contribution of myofibroblasts with prominent fibroblasts. Propranolol treatment of Mdr2(-/-) mice improved liver architecture. Additionally, inflammation and fibrosis were significantly reduced. After 3 months of treatment, the antifibrotic effect of the β-blockade was most obvious. The transcript levels of procollagen 1A1, TNF-α, TGF-β, CTGF and endothelin-1 were markedly repressed in the portal areas of treated mice. Taken together, these data show that propranolol efficiently delays progression of sclerosing cholangitis. Therefore, the blockade of β-adrenoceptors is a promising option to support future therapeutic strategies in the treatment of human PSC.

Protective effects of Salvia plebeia compound homoplantaginin on hepatocyte injury

Salvia plebeia R. Br is a traditional Chinese herb which has been considered as an inflammatory mediator used for treatment of many infectious diseases including hepatitis. Previously, the compound homoplantaginin was isolated in our group. Hence, we evaluated the protective effects of homoplantaginin on hepatocyte injury. Homoplantaginin displayed an antioxidant property in a cell-free system and showed IC(50) of reduction level of DPPH radical at 0.35 microg/ml. In human hepatocyte HL-7702 cells exposed to H(2)O(2), the addition of 0.1-100 microg/ml of homoplantaginin, which did not have a toxic effect on cell viability, significantly reduced lactate dehydrogenase (LDH) leakage, and increased glutathione (GSH), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) in supernatant. In vivo assay, we employed the model of Bacillus Calmette-Guérin (BCG)/lipopolysaccharide (LPS)-induced hepatic injury mice to evaluate efficacy of homoplantaginin. Homoplantaginin (25-100mg/kg) significantly reduced the increase in serum alanine aminotranseferase (ALT) and aspartate aminotransferase (AST), decreased the levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1). The same treatment also reduced the content of thiobarbituric acid-reactive substances (TBARS), elevated the levels of GSH, GSH-Px and SOD in hepatic homogenate. The histopathological analysis showed that the grade of liver injury was ameliorated with reduction of inflammatory cells and necrosis of liver cells in homoplantaginin treatment mice. These results suggest that homoplantaginin has a protective and therapeutic effect on hepatocyte injury, which might be associated with its antioxidant properties.