The antiprotozoal drug nitazoxanide improves experimental liver fibrosis in mice.

Nitazoxanide is an FDA-approved antiprotozoal drug. Our previous studies find that nitazoxanide and its metabolite tizoxanide affect AMPK, STAT3, and Smad2/3 signals which are involved in the pathogenesis of liver fibrosis, therefore, in the present study, we examined the effect of nitazoxanide on experimental liver fibrosis and elucidated the potential mechanisms. The in vivo experiment results showed that oral nitazoxanide (75, 100 mg·kg-1) significantly improved CCl4- and bile duct ligation-induced liver fibrosis in mice. Oral nitazoxanide activated the inhibited AMPK and inhibited the activated STAT3 in liver tissues from liver fibrosis mice. The in vitro experiment results showed that nitazoxanide and its metabolite tizoxanide activated AMPK and inhibited STAT3 signals in LX-2 cells (human hepatic stellate cells). Nitazoxanide and tizoxanide inhibited cell proliferation and collagen I expression and secretion of LX-2 cells. Nitazoxanide and tizoxanide inhibited transforming growth factor-ß1 (TGF-ß1)- and IL-6-induced increases of cell proliferation, collagen I expression and secretion, inhibited TGF-ß1- and IL-6-induced STAT3 and Smad2/3 activation in LX-2 cells. In mouse primary hepatic stellate cells, nitazoxanide and tizoxanide also activated AMPK, inhibited STAT3 and Smad2/3 activation, inhibited cell proliferation, collagen I expression and secretion. In conclusion, nitazoxanide inhibits liver fibrosis and the underlying mechanisms involve AMPK activation, and STAT3 and Smad2/3 inhibition.

Nitazoxanide protects against experimental ulcerative colitis through improving intestinal barrier and inhibiting inflammation.

Ulcerative colitis is a chronic disease with colonic mucosa injury. Nitazoxanide is an antiprotozoal drug in clinic. Nitazoxanide and its metabolite tizoxanide have been demonstrated to activate AMPK and inhibit inflammation, therefore, the aim of the present study is to investigate the effect of nitazoxanide on dextran sulfate sodium (DSS)-induced colitis and the underlying mechanism. Oral administration of nitazoxanide ameliorated the symptoms of mice with DSS-induced colitis, as evidenced by improving the increased disease activity index (DAI), the decreased body weight, and the shortened colon length. Oral administration of nitazoxanide ameliorated DSS-induced intestinal barrier dysfunction and reduced IL-6 and IL-17 expression in colon tissues. Mechanistically, nitazoxanide and its metabolite tizoxanide treatment activated AMPK and inhibited JAK2/STAT3 signals. Nitazoxanide and tizoxanide treatment increased caudal type homeobox 2 (CDX2) expression, increased alkaline phosphatase (ALP) activity and promoted tight junctions in Caco-2 cells. Nitazoxanide and tizoxanide treatment restored the decreased zonula occludens-1(ZO-1) and occludin protein levels induced by LPS or IL-6 in Caco-2 cells. On the other hand, nitazoxanide and tizoxanide regulated macrophage bias toward M2 polarization, as evidenced by the increased arginase-1expression in bone marrow-derived macrophages (BMDM). Nitazoxanide and tizoxanide reduced the increased IL-6, iNOS and CCL2 pro-inflammatory gene expressions and inhibited JAK2/STAT3 activation in BMDM induced by LPS. In conclusion, nitazoxanide protects against DSS-induced ulcerative colitis in mice through improving intestinal barrier and inhibiting inflammation and the underlying mechanism involves AMPK activation and JAK2/STAT3 inhibition.

Effect of stearyl alcohol on imiquimod-induced psoriasis-like skin inflammation in mice.

Psoriasis is a chronic inflammatory skin disease. Topical medicines are the preferred treatment for mild to moderate psoriasis, but the effect of excipients used in semi-solid preparations on psoriasis-like skin inflammation is not fully understood. In the present study, we investigated the effect of stearyl alcohol, a commonly used excipient, on imiquimod (IMQ)-induced psoriasis-like skin inflammation in mice. Psoriasis-like skin inflammation was induced by topical IMQ treatment on the back of mice. Skin lesion severity was evaluated by using psoriasis area and severity index (PASI) scores. The skin sections were stained by haematoxylin-eosin and immunohistochemistry. Stearyl alcohol (20% in vaseline) treatment significantly reduced the IMQ-induced increase of PASI scores and epidermal thickness in mice. IMQ treatment increased the number of Ki67- and proliferating cell nuclear antigen (PCNA)-positive cells in the skin, and the increases were inhibited by stearyl alcohol (20% in vaseline) treatment. Stearyl alcohol treatment (1%, 5%, 10% in vaseline) dose-dependently ameliorated IMQ-induced increase of PASI scores and epidermal thickness in mice. Hexadecanol (20% in vaseline), stearic acid (20% in vaseline) and vaseline treatment had no significant effect on IMQ-induced psoriasis-like skin inflammation in mice. In conclusion, stearyl alcohol has the effect of improving IMQ-induced psoriasis-like skin inflammation in mice.

Sorafenib extends the lifespan of C. elegans through mitochondrial uncoupling mechanism.

Sorafenib is a targeted anticancer drug in clinic. Low-dose sorafenib has been reported to activate AMPK through inducing mitochondrial uncoupling without detectable toxicities. AMPK activation has been the approach for extending lifespan, therefore, we investigated the effect of sorafenib on lifespan and physical activity of C. elegans and the underlying mechanisms. In the present study, we found that the effect of sorafenib on C. elegans lifespan was typically hermetic. Sorafenib treatment at higher concentrations (100 µM) was toxic but at lower concentrations (1, 2.5, 5 µM) was beneficial to C. elegans. Sorafenib (1 µM) treatment for whole-life period extended C. elegans lifespan and improved C. elegans physical activity as manifested by increasing pharyngeal pumping and body movement, preserving intestinal barrier integrity, muscle fibers organization and mitochondrial morphology. In addition, sorafenib (1 µM) treatment enhanced C. elegans stress resistance. Sorafenib activated AMPK through inducing mitochondrial uncoupling in C. elegans. Sorafenib treatment activated DAF-16, SKN-1, and increased SOD-3, HSP-16.2, GST-4 expression in C. elegans. Sorafenib treatment induced AMPK-dependent autophagy in C. elegans. We conclude that low-dose sorafenib protects C. elegans against aging through activating AMPK/DAF-16 dependent anti-oxidant pathways and stimulating autophagy responses. Low-dose sorafenib could be a strategy for treating aging and aging-related diseases.

Anthelmintic nitazoxanide protects against experimental pulmonary fibrosis.

BACKGROUND AND PURPOSE: Nitazoxanide is a therapeutic anthelmintic drug. Our previous studies found that nitazoxanide and its metabolite tizoxanide activated adenosine 5'-monophosphate-activated protein kinase (AMPK) and inhibited signal transducer and activator of transcription 3 (STAT3) signals. As AMPK activation and/or STAT3 inhibition are targets for treating pulmonary fibrosis, we hypothesized that nitazoxanide would be effective in experimental pulmonary fibrosis. EXPERIMENTAL APPROACH: The mitochondrial oxygen consumption rate of cells was measured by using the high-resolution respirometry system Oxygraph-2K. The mitochondrial membrane potential of cells was evaluated by tetramethyl rhodamine methyl ester (TMRM) staining. The target protein levels were measured by using western blotting. The mice pulmonary fibrosis model was established through intratracheal instillation of bleomycin. The examination of the lung tissues changes were carried out using haematoxylin and eosin (H&E), and Masson staining. KEY RESULTS: Nitazoxanide and tizoxanide activated AMPK and inhibited STAT3 signalling in human lung fibroblast cells (MRC-5 cells). Nitazoxanide and tizoxanide inhibited transforming growth factor-ß1 (TGF-ß1)-induced proliferation and migration of MRC-5 cells, collagen-I and α-smooth muscle cell actin (α-SMA) expression, and collagen-I secretion from MRC-5 cells. Nitazoxanide and tizoxanide inhibited epithelial-mesenchymal transition (EMT) and inhibited TGF-ß1-induced Smad2/3 activation in mouse lung epithelial cells (MLE-12 cells). Oral administration of nitazoxanide reduced the bleomycin-induced mice pulmonary fibrosis and, in the established bleomycin-induced mice, pulmonary fibrosis. Delayed nitazoxanide treatment attenuated the fibrosis progression. CONCLUSIONS AND IMPLICATIONS: Nitazoxanide improves the bleomycin-induced pulmonary fibrosis in mice, suggesting a potential application of nitazoxanide for pulmonary fibrosis treatment in the clinic.

Piezo1 channel activation stimulates ATP production through enhancing mitochondrial respiration and glycolysis in vascular endothelial cells.

BACKGROUND AND PURPOSE: Piezo1 channels are mechanosensitive cationic channels that are activated by mechanical stretch or shear stress. Endothelial Piezo1 activation by shear stress caused by blood flow induces ATP release from endothelial cells; however, the link between shear stress and endothelial ATP production is unclear. EXPERIMENTAL APPROACH: The mitochondrial respiratory function of cells was measured by using high-resolution respirometry system Oxygraph-2k. The intracellular Ca2+ concentration was evaluated by using Fluo-4/AM and mitochondrial Ca2+ concentration by Rhod-2/AM. KEY RESULTS: The specific Piezo1 channel activator Yoda1 or its analogue Dooku1 increased [Ca2+ ]i in human umbilical vein endothelial cells (HUVECs), and both Yoda1 and Dooku1 increased mitochondrial oxygen consumption rates (OCRs) and mitochondrial ATP production in HUVECs and primary cultured rat aortic endothelial cells (RAECs). Knockdown of Piezo1 inhibited Yoda1- and Dooku1-induced increases of mitochondrial OCRs and mitochondrial ATP production in HUVECs. The shear stress mimetics, Yoda1 and Dooku1, and the Piezo1 knock-down technique also demonstrated that Piezo1 activation increased glycolysis in HUVECs. Chelating extracellular Ca2+ with EGTA or chelating cytosolic Ca2+ with BAPTA-AM did not affect Yoda1- and Dooku1-induced increases of mitochondrial OCRs and ATP production, but chelating cytosolic Ca2+ inhibited Yoda1- and Dooku1-induced increase of glycolysis. Confocal microscopy showed that Piezo1 channels are present in mitochondria of endothelial cells, and Yoda1 and Dooku1 increased mitochondrial Ca2+ in endothelial cells. CONCLUSION AND IMPLICATIONS: Piezo1 channel activation stimulates ATP production through enhancing mitochondrial respiration and glycolysis in vascular endothelial cells, suggesting a novel role of Piezo1 channel in endothelial ATP production.

Repurposing nitazoxanide as a novel anti-atherosclerotic drug based on mitochondrial uncoupling mechanisms.

BACKGROUND AND PURPOSE: The anthelmintic drug nitazoxanide has a mitochondrial uncoupling effect. Mitochondrial uncouplers have been proven to inhibit smooth muscle cell proliferation and migration, inhibit NLRP3 inflammasome activation of macrophages and improve dyslipidaemia. Therefore, we aimed to demonstrate that nitazoxanide would protect against atherosclerosis. EXPERIMENTAL APPROACH: The mitochondrial oxygen consumption of cells was measured by using the high-resolution respirometry system, Oxygraph-2K. The proliferation and migration of A10 cells were measured by using Edu immunofluorescence staining, wound-induced migration and the Boyden chamber assay. Protein levels were measured by using the western blot technique. ApoE (-/-) mice were fed with a Western diet to establish an atherosclerotic model in vivo. KEY RESULTS: The in vitro experiments showed that nitazoxanide and tizoxanide had a mitochondrial uncoupling effect and activated cellular AMPK. Nitazoxanide and tizoxanide inhibited serum- and PDGF-induced proliferation and migration of A10 cells. Nitazoxanide and tizoxanide inhibited NLRP3 inflammasome activation in RAW264.7 macrophages, the mechanism by which involved the AMPK/IκBα/NF-κB pathway. Nitazoxanide and tizoxanide also induced autophagy in A10 cells and RAW264.7 macrophages. The in vivo experiments demonstrated that oral administration of nitazoxanide reduced the increase in serum IL-1ß and IL-6 levels and suppressed atherosclerosis in Western diet-fed ApoE (-/-) mice. CONCLUSION AND IMPLICATIONS: Nitazoxanide inhibits the formation of atherosclerotic plaques in ApoE (-/-) mice fed on a Western diet. In view of nitazoxanide being an antiprotozoal drug already approved by the FDA, we propose it as a novel anti-atherosclerotic drug with clinical translational potential.

Anthelmintic niclosamide attenuates pressure-overload induced heart failure in mice.

The heart is a high energy demand organ and enhancing mitochondrial function is proposed as the next-generation therapeutics for heart failure. Our previous study found that anthelmintic drug niclosamide enhanced mitochondrial respiration and increased adenosine triphosphate (ATP) production in cardiomyocytes, therefore, this study aimed to determine the effect of niclosamide on heart failure in mice and the potential molecular mechanisms. The heart failure model was induced by transverse aortic constriction (TAC) in mice. Oral administration of niclosamide improved TAC-induced cardiac hypertrophy, cardiac fibrosis, and cardiac dysfunction in mice. Oral administration of niclosamide reduced TAC-induced increase of serum IL-6 in heart failure mice. In vitro, niclosamide within 0.1 µM increased mitochondrial respiration and ATP production in mice heart tissues. At the concentrations more than 0.1 µM, niclosamide reduced the increased interleukin- 6 (IL-6) mRNA expression in lipopolysaccharide (LPS)-stimulated RAW264.7 and THP-1 derived macrophages. In cultured primary cardiomyocytes and cardiac fibroblasts, niclosamide (more than 0.1 µM) suppressed IL-6- and phenylephrine-induced cardiomyocyte hypertrophy, and inhibited collagen secretion from cardiac fibroblasts. In conclusion, niclosamide attenuates heart failure in mice and the underlying mechanisms include enhancing mitochondrial respiration of cardiomyocytes, inhibiting collagen secretion from cardiac fibroblasts, and reducing the elevated serum inflammatory mediator IL-6. The present study suggests that niclosamide might be therapeutic for heart failure.

Chemical mitochondrial uncouplers share common inhibitory effect on NLRP3 inflammasome activation through inhibiting NFκB nuclear translocation.

Activation of NLRP3 inflammasome is implicated in varieties of pathologies, the aim of the present study is to characterize the effect and mechanism of mitochondrial uncouplers on NLRP3 inflammasome activation by using three types of uncouplers, niclosamide, CCCP and BAM15. Niclosamide, CCCP and BAM15 inhibited LPS plus ATP-induced increases of NLRP3 protein and IL-1ß mRNA levels in RAW264.7 macrophages and THP-1 derived macrophages. Niclosamide, CCCP and BAM15 inhibited LPS plus ATP-induced increase of NFκB (P65) phosphorylation, and inhibited NFκB (P65) nuclear translocation in RAW264.7 macrophages. Niclosamide and BAM15 inhibited LPS-induced increase of IκBα phosphorylation in RAW264.7 macrophages, and the inhibitory effect was dependent on increased intracellular [Ca2+]i; however, CCCP showed no significant effect on IκBα phosphorylation in RAW264.7 macrophages stimulated with LPS. In conclusion, chemical mitochondrial uncouplers niclosamide, CCCP and BAM15 share common inhibitory effect on NLRP3 inflammasome activation through inhibiting NFκB nuclear translocation.

Injectable pegylated niclosamide (polyethylene glycol-modified niclosamide) for cancer therapy.

Niclosamide is an antihelminthic drug. Recent studies show that niclosamide exerts antitumor activity through inhibiting multiple signals including Wnt/ß-catenin, mTORC1, signal transducer and activator of transcription 3, NF-κB, notch signals; however, the insolubility and poor bioavailability limits its potential clinic use, the aim of the present work is to synthesize an injectable pegylated niclosamide (polyethylene glycol-modified niclosamide) and investigate its antitumor activity in vitro and in vivo. The pegylated niclosamide (mPEG5000-Nic) was synthesized and the chemical structure was identified by Fourier transform infrared spectra and 1 H nuclear magnetic resonance spectra. The antitumor activity was evaluated in CT26 and HCT116 colon cancer cells in vitro and nude mouse xenograft model of CT26 cells in vivo. The water solubility of niclosamide in mPEG5000-Nic was significantly increased. Niclosamide could be released from mPEG5000-Nic nanoparticles in PBS solution. mPEG5000-Nic inhibited the cell viability of CT26 and HCT116 cells in vitro. No animal death was observed in mice with intraperitoneal injection of mPEG5000-Nic (equivalent to 1000 mg/kg niclosamide) within 24 hr, indicating that mPEG5000-Nic was less toxic. In nude mouse, xenograft model of CT26 colon carcinoma, intraperitoneal injection of mPEG5000-Nic (equivalent to niclosamide 50 mg/kg) inhibited tumor growth but had no effect on animal body weight and heart, liver, kidney, and lung weight in vivo. Meanwhile, in the same model, intraperitoneal injection of the positive clinic drug 5-fluorouracil not only inhibited the tumor growth, but also reduced the animal body weight. Our study demonstrates that pegylated niclosamide is novel niclosamide delivery system with clinical perspective for cancer therapy.

Niclosamide ethanolamine induces trachea relaxation and inhibits proliferation and migration of trachea smooth muscle cells.

Our previous study found that the anthelmintic drug niclosamide relaxed the constricted arteries and inhibited proliferation and migration of vascular smooth muscle cells. Here, we investigated the effect of niclosamide ethanolamine (NEN) on trachea function and the proliferation and migration of trachea smooth muscle cells. Isometric tension of trachea was recorded by multi-channel myograph system. The cell proliferation was detected by using BrdU cell proliferation assay. The cell migration ability was evaluated by using scratch assay. The protein level was measured by using western blot technique. Acute treatment with NEN dose-dependently relaxed acetylcholine chloride (Ach)- and High K+ physiological salt solution (KPSS)-induced constriction of mice trachea. Pre-treatment with NEN inhibited Ach- and KPSS-induced constriction of mice trachea. NEN treatment inhibited proliferation of human bronchial smooth muscle cells (HBSMCs), inhibited migration of HBSMCs and rat primary trachea smooth muscle cells. NEN treatment activated adenosine monophosphate activated protein kinase (AMPK) activity and inhibited signal transducer and activator of transcription 3 (STAT3) activity in HBSMCs. In conclusion, niclosamide ethanolamine induces trachea relaxation and inhibits proliferation and migration of trachea smooth muscle cells, indicating that niclosamide might be a potential drug for chronic asthma treatment.

The different response of cardiomyocytes and cardiac fibroblasts to mitochondria inhibition and the underlying role of STAT3.

Cardiomyocyte loss and cardiac fibrosis are the main characteristics of cardiac ischemia and heart failure, and mitochondrial function of cardiomyocytes is impaired in cardiac ischemia and heart failure, so the aim of this study is to identify fate variability of cardiomyocytes and cardiac fibroblasts with mitochondria inhibition and explore the underlying mechanism. The mitochondrial respiratory function was measured by using Oxygraph-2k high-resolution respirometry. The STAT3 expression and activity were evaluated by western blot. Cardiomyocytes and cardiac fibroblasts displayed different morphology. The mitochondrial respiratory function and the expressions of mitochondrial complex I, II, III, IV, and V of cardiac fibroblasts were lower than that of cardiomyocytes. Mitochondrial respiratory complex I inhibitor rotenone and H2O2 (100 µM, 4 h) treatment induced cell death of cardiomyocyte but not cardiac fibroblasts. The function of complex I/II was impaired in cardiomycytes but not cardiac fibroblasts stimulated with H2O2 (100 µM, 4 h) and in ischemic heart of mice. Rotenone and H2O2 (100 µM, 4 h) treatment reduced STAT3 expression and activity in cardiomyocytes but not cardiac fibroblasts. Inhibition of STAT3 impaired mitochondrial respiratory capacity and exacerbated H2O2-induced cell injury in cardiomycytes but not significantly in cardiac fibroblasts. In conclusion, the different susceptibility of cardiomyocytes and cardiac fibroblasts to mitochondria inhibition determines the cell fate under the same pathological stimuli and in which STAT3 plays a critical role.

Characterizations of mitochondrial uncoupling induced by chemical mitochondrial uncouplers in cardiomyocytes.

Induction of mild mitochondrial uncoupling is protective in a variety of disorders; however, it is unclear how to recognize the mild mitochondrial uncoupling induced by chemical mitochondrial uncouplers. The aim of the present study is to identify the pharmacological properties of mitochondrial uncoupling induced by mitochondrial uncouplers in cardiomyocytes. Neonatal rat cardiomyocytes were cultured. Protein levels were measured by using western blot technique. The whole cell respiratory function was determined by using high-resolution respirometry. The typical types of chemical mitochondrial uncouplers, carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP), niclosamide, and BAM15, induced biphasic change of STAT3 activity in cardiomyocytes, activating STAT3 at low dose and inhibiting STAT3 at high dose, though the dose range of these drugs was distinct. Low-dose uncouplers induced STAT3 activation through the mild increase of mitochondrial ROS (mitoROS) generation and the subsequent JAK/STAT3 activation in cardiomyocytes. However, high-dose uncouplers induced inhibition of STAT3, decrease of ATP production, and cardiomyocyte death. High-dose uncouplers induced STAT3 inhibition through the excessive mitoROS generation and the decreased ATP -induced AMPK activation. Low-dose mitochondrial uncouplers attenuated doxorubicin (DOX)-induced STAT3 inhibition and cardiomyocyte death, and activated STAT3 contributed to the cardioprotection of low-dose mitochondrial uncouplers. Uncoupler-induced mild mitochondrial uncoupling in cardiomyocytes is characterized by STAT3 activation and ATP increase whereas excessive mitochondrial uncoupling is characterized by STAT3 inhibition, ATP decrease and cell injury. Development of mitochondrial uncoupler with optimal dose window of inducing mild uncoupling is a promising strategy for heart protection.

Niclosamide inhibits vascular smooth muscle cell proliferation and migration and attenuates neointimal hyperplasia in injured rat carotid arteries.

BACKGROUND AND PURPOSE: The anti-helminthic drug niclosamide regulates multiple cellular signals including STAT3, AMP-activated protein kinase (AMPK), Akt, Wnt/ß-catenin and mitochondrial uncoupling which are involved in neointimal hyperplasia. Here we have examined the effects of niclosamide on vascular smooth muscle cell proliferation, migration and neointimal hyperplasia and assessed the potential mechanisms. EXPERIMENTAL APPROACH: Cell migration was measured by using wound-induced migration assay and Boyden chamber assay. Protein levels were measured by using Western blot technique. Neointimal hyperplasia in vivo was induced in rats by balloon injury to the carotid artery. KEY RESULTS: Niclosamide treatment inhibited serum-induced (15% FBS) and PDGF-BB-induced proliferation and migration of vascular smooth muscle cells (A10 cells). Niclosamide showed no cytotoxicity at anti-proliferative concentrations, but induced cell apoptosis at higher concentrations. Niclosamide treatment inhibited serum-induced (15% FBS) and PDGF-BB-induced STAT3 activation (increased protein levels of p-STAT3 at Tyr705 ) but activated AMPK, in A10 cells. Niclosamide exerted no significant effects on ß-catenin expression and the activities of ERK1/2 and Akt in A10 cells. Injection (i.p.) of soluble pegylated niclosamide (PEG5000-niclosamide) (equivalent to niclosamide 25 mg·kg-1 ) attenuated neointimal hyperplasia following balloon-injury in rat carotid arteries in vivo. CONCLUSIONS AND IMPLICATIONS: Niclosamide inhibited vascular smooth muscle cell proliferation and migration and attenuated neointimal hyperplasia in balloon-injured rat carotid arteries through a mechanism involving inhibition of STAT3.

Mitochondrial Fission Inhibitors Suppress Endothelin-1-Induced Artery Constriction.

BACKGROUND/AIMS: Endothelin-1 is implicated in the pathogenesis of hypertension, but the underlying mechanisms remained elusive. Our previous study found that inhibition of mitochondrial fission of smooth muscle cells suppressed phenylephrine- and high K+-induced artery constriction. Here, we studied the effects of mitochondrial fission inhibitors on endothelin-1-induced vasoconstriction. METHODS: The tension of rat mesenteric arteries and thoracic aorta was measured by using a multi-wire myograph system. Mitochondrial morphology of aortic smooth muscle cells was observed by using transmission electron microscopy. RESULTS: Dynamin-related protein-1 selective inhibitor mdivi-1 relaxed endothelin-1-induced constriction, and mdivi-1 pre-treatment prevented endothelin-1-induced constriction of rat mesenteric arteries with intact and denuded endothelium. Mdivi-1 had a similar inhibitory effect on rat thoracic aorta. Another mitochondrial fission inhibitor dynasore showed similar effects as mdivi-1 in rat mesenteric arteries. Mdivi-1 inhibited endothelin-1-induced increase of mitochondrial fission in smooth muscle cells of rat aorta. Rho-associated protein kinase inhibitor Y-27632 which relaxed endothelin-1-induced vasoconstriction inhibited endothelin-1-induced mitochondrial fission in smooth muscle cells of rat aorta. CONCLUSION: Endothelin-1 increases mitochondrial fission in vascular smooth muscle cells, and mitochondrial fission inhibitors suppress endothelin-1-induced vasoconstriction.

Design, synthesis and characterization of poly (methacrylic acid-niclosamide) and its effect on arterial function.

We have found that niclosamide induced relaxation of constricted artery. However, niclosamide is insoluble, the low bioavailability and the resultant low plasma concentration limit its potential exertion in vivo. The aim of the present study is to synthesize a soluble poly (methacrylic acid-niclosamide) polymer (PMAN) and study the effects of PMAN on arterial function in vitro and the blood pressure and heart rate of rats in vivo. We synthesized the poly (methacrylic acid-niclosamide) polymer (PMAN), the chemical structure of which was identified by FTIR and 1H NMR spectra. The average molecular weight and polydispersity index of PMAN were 5138 and 1.193 respectively. Compared with niclosamide, the water solubility of niclosamide in PMAN was significantly increased. PMAN showed dose-dependent vasorelaxation effect on rat mesenteric arteries with intact or denuded endothelium in phenylephrine (PE) and high K+ (KPSS)-induced vasoconstriction models in vitro. The efficacy of vasorelaxant effect and the cytotoxic effect of PMAN on vascular smooth muscle cells (A10) were lower than that of niclosamide. The LD50 of PMAN in mice (iv) was 80mg/kg. Venous injection of PMAN (equivalent 5mg niclosamide per kg) showed acute reduction of the rat blood pressure and heart rate in vivo. In conclusion, the solubility of niclosamide was increased in the way of poly (methacrylic acid-niclosamide) polymer, which relaxes the constricted arteries in vitro and reduces the rat blood pressure and heart rate in vivo, indicating that modifying niclosamide solubility through polymerization is a feasible approach to improve its pharmacokinetic profiles for potential clinic application.

Niclosamide ethanolamine inhibits artery constriction.

We previously demonstrated that the typical mitochondrial uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP) inhibited artery constriction, but CCCP was used only as a pharmacological tool. Niclosamide is an anthelmintic drug approved by FDA. Niclosamide ethanolamine (NEN) is a salt form of niclosamide and has been demonstrated to uncouple mitochondrial oxidative phosphorylation. The aim of the present study was to elucidate the vasoactivity of NEN and the potential mechanisms. Isometric tension of rat mesenteric artery and thoracic aorta was recorded by using multi-wire myograph system. The protein levels were measured by using western blot techniques. Niclosamide ethanolamine (NEN) treatment relaxed phenylephrine (PE)- and high K+ (KPSS)-induced constriction, and pre-treatment with NEN inhibited PE- and KPSS-induced constriction of rat mesenteric arteries. In rat thoracic aorta, NEN also showed antagonism against PE- and KPSS-induced constriction. NEN induced increase of cellular ADP/ATP ratio in vascular smooth muscle cells (A10) and activated AMP-activated protein kinase (AMPK) in A10 cells and rat thoracic aorta. NEN-induced aorta relaxation was attenuated in AMPKα1 knockout (-/-) mice. SERCA inhibitors cyclopiazonic acid and thapsigargin, but not KATP channel blockers glibenclamide and 5-hydroxydecanoic acid, attenuated NEN-induced vasorelaxation in rat mesenteric arteries. NEN treatment increased cytosolic [Ca2+]i and depolarized mitochondrial membrane potential in vascular smooth muscle cells (A10). Niclosamide in non-salt form showed the similar vasoactivity as NEN in rat mesenteric arteries. Niclosamide ethanolamine inhibits artery constriction, indicating that it would be promising to be developed as an anti-hypertensive drug or it would induce vasodilation-related side effects when absorbed in vivo.

Mitochondrial Fission of Smooth Muscle Cells Is Involved in Artery Constriction.

Mitochondria are dynamic organelles and continuously undergo fission and fusion processes. Mitochondrial fission is involved in multiple physiological or pathological processes, but the role of mitochondrial fission of smooth muscle cells in artery constriction is unknown. The role of mitochondrial fission of smooth muscle cells in arterial function was investigated by measuring the tension of rat mesenteric arteries and thoracic aorta and by evaluating mitochondrial fission, mitochondrial reactive oxygen species, and cytosolic [Ca2+]i in rat vascular smooth muscle cells. Mitochondrial fission inhibitors mdivi-1 and dynasore antagonized phenylephrine- and high K+-induced constriction of rat mesenteric arteries. Mdivi-1 relaxed phenylephrine-induced constriction, and mdivi-1 pretreatment prevented phenylephrine-induced constriction in mice, rat aorta, and human mesenteric arteries. Phenylephrine- and high K+-induced increase of mitochondrial fission in smooth muscle cells of rat aorta and the increase was inhibited by mdivi-1. Mdivi-1 inhibited high K+-induced increases of mitochondrial fission, mitochondrial reactive oxygen species, and cytosolic [Ca2+]i in rat vascular smooth muscle cells. Prechelation of cytosolic Ca2+ prevented high K+-induced cytosolic [Ca2+]i increase, mitochondrial fission, and mitochondrial reactive oxygen species overproduction. Mitochondria-targeted antioxidant mito-TEMPO antagonized phenylephrine- and high K+-induced constriction of rat mesenteric arteries. Nitroglycerin and ROCK (Rho-associated protein kinase) inhibitor Y27632, the 2 vasodilators with different vasorelaxant mechanisms, relaxed high K+-induced vasoconstriction and inhibited high K+-induced mitochondrial fission. In conclusion, the mitochondrial fission of smooth muscle cells is involved in artery constriction.

Mitochondrial uncoupler carbonyl cyanide m-chlorophenylhydrazone induces vasorelaxation without involving KATP channel activation in smooth muscle cells of arteries.

BACKGROUND AND PURPOSE: The effects and mechanisms of chemical mitochondrial uncouplers on vascular function have never been identified. Here, we characterized the effects of the typical mitochondrial uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP) on vascular function in rat mesenteric arteries and aorta and elucidated the potential mechanisms. EXPERIMENTAL APPROACH: Isometric tension of mesenteric artery and thoracic aorta was recorded by using a multiwire myograph system. Protein levels were measured by western blot analyses. Cytosolic [Ca2+ ]i , mitochondrial ROS (mitoROS) and mitochondrial membrane potential of smooth muscle cells (A10) were measured by laser scanning confocal microscopy. KEY RESULTS: Acute treatment with CCCP relaxed phenylephrine (PE)- and high K+ (KPSS)-induced constriction of rat mesenteric arteries with intact and denuded endothelium. Pretreatment with CCCP prevented PE- and KPSS-induced constriction of rat mesenteric arteries with intact and denuded endothelium. Similarly, CCCP prevented PE- and KPSS-induced constriction of rat thoracic aorta. CCCP increased the cellular ADP/ATP ratio in vascular smooth muscle cells (A10) and activated AMPK in A10 cells and rat thoracic aorta tissues. CCCP-induced aorta relaxation was attenuated in AMPK α1 knockout (-/-) mice. SERCA inhibitors thapsigargin and cyclopiazonic acid (CPA) but not the KATP channel blocker glibenclamide partially inhibited CCCP-induced vasorelaxation in endothelium-denuded rat mesenteric arteries. CCCP increased cytosolic [Ca2+ ]i , mitoROS production and depolarized mitochondrial membrane potential in A10 cells. FCCP, the analogue of CCCP, had similar vasoactivity as CCCP in rat mesenteric arteries. CONCLUSIONS AND IMPLICATIONS: CCCP induces vasorelaxation by a mechanism that does not involve KATP channel activation in smooth muscle cells of arteries.