Combined administration of propranolol + AG490 offers better effects on portal hypertensive rats with cirrhosis

Adrenergic receptors blockade alleviates dexamethasone-induced neurotoxicity in adult male Wistar rats: Distinct effects on β-arrestin2 expression and molecular markers of neural injury

BACKGROUND

Dexamethasone-induced neurotoxicity has been previously reported. However, the molecular mechanisms are still not completely understood.

OBJECTIVES

The current work aimed to investigate the modulatory effects of α- and β-adrenergic receptors on dexamethasone-induced neurotoxicity in rats focused on changes in β-arrestin2 and molecular markers of neural injury in cerebral cortex.

METHODS

Male Wistar rats were subcutaneously injected with dexamethasone (10 mg/kg/day) for 7 days to induce neural injury in the cerebral cortex. The experiment involved 5 groups: control, dexamethasone, carvedilol, propranolol, and doxazosin. In the last 3 groups, drugs were given 2 hours before dexamethasone injection. At the end of experiment, brain samples were collected for measurement of brain derived neurotrophic factor (BDNF), glial fibrillary acidic protein (GFAP), kinase activity of protein kinase B (Akt), diacylglycerol (DAG), α-smooth muscle actin (α-SMA), Smad3, β-amyloid and phospho-tau protein levels in addition to histopathological examination of brain tissue using hematoxylin-eosin, Nissl, and Sirius red stains. Moreover, β-arrestin2 levels in the cerebral cortex were measured using immunohistochemical examination.

RESULTS

Dexamethasone slightly reduced brain weight and significantly decreased BDNF, Akt kinase activity and β-arrestin2 but markedly induced degeneration of cortical neurons and significantly increased GFAP, DAG, α-SMA, Smad3, β-amyloid and phospho-tau protein levels compared to controls. Carvedilol, propranolol, and doxazosin reversed all dexamethasone-induced molecular changes and slightly ameliorated the histopathological changes. Carvedilol significantly increased brain weight and β-arrestin2 levels compared to dexamethasone, propranolol, and doxazosin groups.

CONCLUSION

blocking α- and/or β-adrenergic receptors alleviate dexamethasone-induced neurotoxicity despite their distinct effects on β-arrestin2 levels in the cerebral cortex.

Curcumol Attenuates Portal Hypertension and Collateral Shunting Via Inhibition of Extrahepatic Angiogenesis in Cirrhotic Rats

Liver cirrhosis can cause disturbances in blood circulation in the liver, resulting in impaired portal blood flow and ultimately increasing portal venous pressure. Portal hypertension induces portal-systemic collateral formation and fatal complications. Extrahepatic angiogenesis plays a crucial role in the development of portal hypertension. Curcumol is a sesquiterpenoid derived from the rhizome of Curcumae Rhizoma and has been confirmed to alleviate liver fibrosis by inhibiting angiogenesis. Therefore, our study was designed to explore the effects of curcumol on extrahepatic angiogenesis and portal hypertension. To induce cirrhosis, Sprague Dawley rats underwent bile duct ligation (BDL) surgery. Rats received oral administration with curcumol (30 mg/kg/d) or vehicle (distilled water) starting on day 15 following surgery, when BDL-induced liver fibrosis had developed. The effect of curcumol was assessed on day 28, which is the typical time of BDL-induced cirrhosis. The results showed that curcumol markedly reduced portal pressure in cirrhotic rats. Curcumol inhibited abnormal splanchnic inflow, mitigated liver injury, improved liver fibrosis, and attenuated portal-systemic collateral shunting in cirrhotic rats. These protective effects were partially attributed to the inhibition on mesenteric angiogenesis by curcumol. Mechanically, curcumol partially reversed the BDL-induced activation of the JAK2/STAT3 signaling pathway in cirrhotic rats. Collectively, curcumol attenuates portal hypertension in liver cirrhosis by suppressing extrahepatic angiogenesis through inhibiting the JAK2/STAT3 signaling pathway.

Effect and mechanism of HMG-CoA reductase inhibitor on the improvement of elderly essential hypertension-induced vascular endothelial function impairment based on the JAK/STAT pathway

OBJECTIVE

Our research was designed to figure out the influence and mechanism of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor on the improvement of elderly essential hypertension-induced vascular endothelial function impairment based on the JAK/STAT pathway.

METHODS

Eighty-six elderly patients with essential hypertension were randomized into a control group (oral Amlodipine Besylate Tablets) and an observation group (oral Amlodipine Besylate Tablets + HMG-CoA reductase inhibitor atorvastatin calcium). Patients in both groups were treated with the drug for 12 weeks. Blood pressure, serum levels of inflammatory factors, and vascular endothelial function indicators, and levels of blood lipids were measured. The modeled rats were treated with atorvastatin calcium and a JAK/STAT pathway inhibitor (AG490), and the levels of cardiac function-related indices, left ventricular mass index, lipid levels, serum inflammatory factors and vascular endothelial function-related indices were detected in each group.

RESULTS

HMG-CoA reductase inhibitor improved blood pressure levels, lipid levels, serum inflammatory factor levels and cardiac function in elderly patients with essential hypertension. Both HMG-CoA reductase inhibitor and AG490 improved blood pressure levels, lipid levels, serum inflammatory factor levels and cardiac function in SHR rats. Both HMG-CoA reductase inhibitor and AG490 decreased p-JAK2/JAK2 and p-STAT3/STAT3 expression levels.

CONCLUSION

Our study demonstrates that HMG-CoA reductase inhibitor improves elderly essential hypertension-induced vascular endothelial function impairment by blocking the JAK/STAT pathway.

Downregulation of miR-20b-5p Contributes to the Progression of Liver Fibrosis via the STAT3 Signaling Pathway In Vivo and In Vitro

BACKGROUND

Activated hepatic stellate cells (HSCs) are primarily involved in liver fibrosis and portal hypertension (PHT). We aimed to investigate the effect of miR-20b-5p on HSCs, liver fibrosis, and PHT.

METHODS

MiR-20b-5p expression in HSCs and in mouse liver fibrosis was determined by qPCR. Further, the effects of miR-20b-5p mimic on HSCs migration, proliferation, and apoptosis were investigated in vitro. A dual-luciferase reporter assay was performed to confirm the direct interaction between miR-20b-5p and STAT3. In vivo, mouse liver fibrosis was established by common bile duct ligation and intervened by agomiR-20b-5p. Sirius red staining and hydroxyproline content were used to evaluate collagen deposition. The α-SMA expression in the liver was detected by IHC and Western blotting. The STAT3 signaling pathway and its downregulated cytokines as well as portal pressure and angiogenesis were explored.

RESULTS

MiR-20b-5p was significantly downregulated during HSCs activation and in mouse liver fibrosis. The functional analyses demonstrated that miR-20b-5p inhibited cell proliferation, activation, and promoted apoptosis in HSCs in vitro. Moreover, miR-20b-5p regulated STAT3 expression by binding to the 3'UTR of its miRNA directly. Overexpression of miR-20b-5p facilitated HSC activation and proliferation by inhibiting the STAT3 signaling pathway. MiR-20b-5p overexpression suppressed the STAT3 and its downstream cytokines and ameliorated liver fibrosis in mice. The intra- and inter-hepatic angiogenesis were also effectively inhibited. The inhibition of liver fibrosis and neoangiogenesis contributed to the decrease of portal pressure.

CONCLUSIONS

MiR-20b-5p plays an important role in the fibrosis and angiogenesis of liver fibrosis by targeting the STAT3 signaling pathway.

Carvedilol ameliorates dexamethasone-induced myocardial injury in rats independent of its action on the α1-adrenergic receptor

The current study aimed to investigate the cardiotoxic effect of dexamethasone-high-dose in rats, the therapeutic effect of carvedilol and the role of α1-adrenergic receptor (α1AR). The experiment involved 6 groups: control, dexamethasone (10 mg/kg), carvedilol (10 mg/kg), phenylephrine (1 mg/kg), phenylephrine plus carvedilol and propranolol (30 mg/kg). Drugs and vehicles were given for 7 days. Dexamethasone was given with the drugs in the last 4 groups. On the 8th-day and after overnight fasting, serum and cardiac samples were collected. Serum levels of cardiac troponin I and creatine kinase-myoglobin as well as cardiac levels of diacylglycerol, malondialdehyde, kinase activity of Akt, transforming growth factor-β, Smad3 and alpha smooth muscle actin were measured. Cardiac samples were also used for histopathological examination using hematoxylin-eosin and Sirius red stains, in addition to immunohistochemical examination using β-arrestin2 antibody. Dexamethasone induced cardiac injury via increasing oxidative stress, apoptosis and profibrotic signals. Carvedilol significantly reduced the dexamethasone-induced cardiotoxicity. Using phenylephrine, a competitive α1-agonist, with carvedilol potentiated the cardioprotective actions of carvedilol. Propranolol, a β-blocker without activity on α1ARs, showed higher cardiac protection than carvedilol. Dexamethasone-high-dose upregulates cardiac oxidative stress, apoptotic and profibrotic signals and induces cardiac injury. Blocking the α1-adrenergic receptor by carvedilol attenuates its cardioprotective effects against dexamethasone-induced cardiotoxicity.

Mitigation of dexamethasone-induced nephrotoxicity by modulating the activity of adrenergic receptors: Implication of Wnt/β-arrestin2/β-catenin pathway

The present study aimed to investigate the role of α and β-adrenergic receptors (βARs) in mediation or modulation of the dexamethasone-induced nephrotoxicity by using different pharmacological interventions. Nephrotoxicity was induced by subcutaneous injection of dexamethasone (10 mg/kg) for 7 days in Wistar albino rats. Eight groups were used: control; dexamethasone; carvedilol; phenylephrine; carvedilol and phenylephrine; propranolol; doxazosin; propranolol and doxazosin. At the end of experiment, rats were euthanized and blood, urine and kidney samples were collected. Serum and urinary creatinine and urinary total protein levels were measured. Also, the renal tissue levels of diacylglycerol (DAG); Akt kinase activity, malondialdehyde (MDA), NADPH oxidase 2 (NOX2), transforming growth factor-β (TGF-β), Wnt3A and β-catenin were recorded. Furthermore, histopathological and β-arrestin2-immunohistochemical examinations of renal tissues were performed. Results: Dexamethasone induced glomerular damage, proteinuria, renal oxidative stress and upregulated the renal Wnt/β-arrestin2/β-catenin pathway and the profibrotic signals. Blocking the α1 and βARs by carvedilol reduced the dexamethasone-induced nephrotoxicity. Pre-injection of phenylephrine did not reduce the reno-protective action of carvedilol. Blocking the βARs only by propranolol reduced the dexamethasone-induced nephrotoxicity to the same extent of carvedilol group. Blocking the α1ARs only by doxazosin reduced dexamethasone-induced nephrotoxicity to a higher extent than other treatments. However, combined use of propranolol and doxazosin did not synergize the reno-protective effects of doxazosin. Conclusion: Dexamethasone induces nephrotoxicity, possibly, by upregulating the Wnt/β-arrestin2/β-catenin pathway. Blocking either α1ARs or βARs can effectively protect against the dexamethasone-induced nephrotoxicity. However, combined blocking of α1ARs and βARs does not synergize the reno-protective effects.

Propranolol and low-dose isoproterenol ameliorate insulin resistance, enhance β-arrestin2 signaling, and reduce cardiac remodeling in high-fructose, high-fat diet-fed mice: Comparative study with metformin

AIMS

β-Arrestin2 signaling has emerged as a promising therapeutic target for the management of insulin resistance and related complications. Moreover, recent studies have shown that certain G protein-coupled receptor (GPCR) ligands can modulate β-arrestin2 signaling. The current study examined the effects of the β-blocker propranolol and a low dose of the agonist isoproterenol (L-D-ISOPROT) on β-arrestin2 signaling, insulin resistance, and cardiac remodeling in high-fructose, high-fat diet (HFrHFD)-fed mice. In addition, the effects of these agents were compared to those of the clinical antidiabetic agent, metformin.

MATERIALS AND METHODS

Insulin resistance was induced by HFrHFD feeding for 16 weeks. Mice were then randomly allocated to groups receiving propranolol, L-D-ISOPROT, metformin, or vehicle (control) for 4 weeks starting on week 13 of HFrHFD feeding. Survival rate, body weight, visceral fat weight, blood glucose, serum insulin, insulin resistance index, hepatic β-arrestin2 signaling, heart weight, left and right ventricular thicknesses, cardiac fibrosis severity, serum endothelin-1, cardiac cardiotrophin-1, and cardiac β-arrestin2 signaling were then compared among groups.

KEY FINDINGS

HFrHFD for 16 weeks significantly increased insulin resistance index, cardiac fibrosis area, and serum endothelin-1, and reduced hepatic β-arrestin2 signaling, cardiac cardiotrophin-1, and cardiac β-arrestin2 signaling without significant changes in survival rate, body weight, visceral fat weight, heart weight, or left and right ventricular thicknesses. All three drugs reduced insulin resistance and cardiac remodeling parameters and enhanced β-arrestin2 signaling with variable efficacies.

SIGNIFICANCE

Propranolol and L-D-ISOPROT, like metformin, can reduce insulin-resistance and cardiac remodeling in HFrHFD-fed mice, possibly by upregulating β-arrestin2 signaling activity. Therefore, β-arrestin2-signaling modulation might be a promising strategy for insulin-resistance treatment.

Portal hypertension in cirrhosis: Pathophysiological mechanisms and therapy

Portal hypertension, defined as increased pressure in the portal vein, develops as a consequence of increased intrahepatic vascular resistance due to the dysregulation of liver sinusoidal endothelial cells (LSECs) and hepatic stellate cells (HSCs), frequently arising from chronic liver diseases. Extrahepatic haemodynamic changes contribute to the aggravation of portal hypertension. The pathogenic complexity of portal hypertension and the unsuccessful translation of preclinical studies have impeded the development of effective therapeutics for patients with cirrhosis, while counteracting hepatic and extrahepatic mechanisms also pose a major obstacle to effective treatment. In this review article, we will discuss the following topics: i) cellular and molecular mechanisms of portal hypertension, focusing on dysregulation of LSECs, HSCs and hepatic microvascular thrombosis, as well as changes in the extrahepatic vasculature, since these are the major contributors to portal hypertension; ii) translational/clinical advances in our knowledge of portal hypertension; and iii) future directions.

Thalidomide for the Treatment of Thrombocytopenia and Hypersplenism in Patients With Cirrhosis or Thalassemia

Hypersplenism and thrombocytopenia are common complications of liver cirrhosis or thalassemia, but current treatment strategies are limited. This study aimed to evaluate the efficacy and safety of thalidomide in the treatment of hypersplenism and thrombocytopenia in patients with liver cirrhosis or thalassemia. A total of 31 patients with hepatic cirrhosis (n=19) or thalassemia (n=12) diagnosed with hypersplenism and thrombocytopenia (platelet count [PLT] <100×10⁹/L) were included in this prospective cohort study between January 2015 and May 2017. Patients were treated with thalidomide (150-200 mg/d) plus conventional therapy. Spleen length, PLT, leukocyte count (WBC), absolute neutrophil count (ANC), and hemoglobin level (Hb) were measured at baseline, 3, 6, and 12 months. Any adverse events were noted. All of the 31 patients were showed a progressive increase PLT during the 12-month follow-up, and similar results were obtained when subgroup analyses were performed based on the primary disease (cirrhosis or thalassemia). WBC, ANC, and Hb also increased progressively during the 12-month follow-up. Spleen length decreased progressively during the follow-up. No serious adverse events occurred. Thalidomide is a potential treatment for thrombocytopenia caused by hypersplenism in patients with cirrhosis or thalassemia.

Advances in therapeutic options for portal hypertension

Portal hypertension represents one of the major clinical consequences of chronic liver disease, having a deep impact on patients' prognosis and survival. Its pathophysiology defines a pathological increase in the intrahepatic vascular resistance as the primary factor in its development, being subsequently aggravated by a paradoxical increase in portal blood inflow. Although extensive preclinical and clinical research in the field has been developed in recent decades, no effective treatment targeting its primary mechanism has been defined. The present review critically summarizes the current knowledge in portal hypertension therapeutics, focusing on those strategies driven by the disease pathophysiology and underlying cellular mechanisms.

Research progress on signaling pathways in cirrhotic portal hypertension

Portal hypertension (PHT) is an important consequence of liver cirrhosis, which can lead to complications that adversely affect a patient’s quality of life and survival, such as upper gastrointestinal bleeding, ascites, and portosystemic encephalopathy. In recent years, advances in molecular biology have led to major discoveries in the pathological processes of PHT, including the signaling pathways that may be involved: PI3K-AKT-mTOR, RhoA/Rho-kinase, JAK2/STAT3, and farnesoid X receptor. However, the pathogenesis of PHT is complex and there are numerous pathways involved. Therefore, the targeting of signaling pathways for medical management is lagging. This article summarizes the progress that has been made in understanding the signaling pathways in PHT, and provides ideas for treatment of the disorder.

Novel treatment options for portal hypertension

Portal hypertension is most frequently associated with cirrhosis and is a major driver for associated complications, such as variceal bleeding, ascites or hepatic encephalopathy. As such, clinically significant portal hypertension forms the prelude to decompensation and impacts significantly on the prognosis of patients with liver cirrhosis. At present, non-selective β-blockers, vasopressin analogues and somatostatin analogues are the mainstay of treatment but these strategies are far from satisfactory and only target splanchnic hyperemia. In contrast, safe and reliable strategies to reduce the increased intrahepatic resistance in cirrhotic patients still represent a pending issue. In recent years, several preclinical and clinical trials have focused on this latter component and other therapeutic avenues. In this review, we highlight novel data in this context and address potentially interesting therapeutic options for the future.

CXCR2 is involved in pulmonary intravascular macrophage accumulation and angiogenesis in a rat model of hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is a lung complication in various liver diseases, with high incidence, poor prognosis and no effective non-surgical treatments in patients with hepatocirrhosis. Therefore, assessing HPS pathogenesis to explore proper therapy strategies is clinically relevant. In the present study, male Sprague–Dawley rats underwent sham operation or common bile duct ligation (CBDL). Two weeks post-surgery, the following groups were set up for 2 weeks of treatment: sham + normal saline, CBDL + CXCR2 antagonist SB225002, CBDL + tumour necrosis factor α (TNF-α) antagonist PTX and CBDL + normal saline groups. Liver and lung tissues were collected after mean arterial pressure (MAP) and portal venous pressure (PVP) measurements. Haematoxylin and eosin (H&E) staining (lung) and Masson staining (liver) were performed for pathological analyses. Finally, pulmonary tissue RNA and total protein were assessed for target effectors. The mRNA and protein levels of CXCR2 were significantly increased in the pulmonary tissue of CBDL rats. What's more, CXCR2 inhibition by SB225002 reduced the expression of CD68 and von Willebrand factor (vWf) in CBDL rats. Importantly, CXCR2 inhibition suppressed the activation of Akt and extracellular signal-regulated kinase (ERK) in CBDL rats. Antagonization of TNF-α with PTX down-regulated the expression of CXCR2. During HPS pathogenesis in rats, CXCR2 might be involved in the accumulation of pulmonary intravascular macrophages and angiogenesis, possibly by activating Akt and ERK, with additional regulation by TNF-α that enhanced pulmonary angiogenesis by directly acting on the pulmonary tissue. Finally, the present study may provide novel targets for the treatment of HPS.