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Background/Aims: Transient receptor potential cation channel 1 (TRPC1)-mediated the calcium (Ca2+) influx plays an important role in several brain disorders. However, the function of TRPC1 in ischemia/reperfusion (I/R)-induced neurological injury is unclear. Methods: Wild-type or TRPC1 knockout mice underwent middle cerebral artery occlusion for 90 min followed by 24 h of reperfusion. In an in vitro study, neuronal cells were treated with oxygen–glucose deprivation and reoxygenation (OGD/R) to mimic I/R. The intracellular Ca2+ concentration [Ca2+]i was measured by Fura 2-AM under a microscope. Cerebral infarct volume was measured by triphenyltetrazolium chloride staining. Neurological function was examined by neurological severity score, Morris water maze test, rotarod test and string test. Oxidative parameters were detected by malondialdehyde, glutathione peroxidase, and superoxide dismutase commercially available kits. The protein expression levels of TRPC1, Nox4, p22phox, p47phox, and p67phox were analyzed by western blotting. Results: Brain tissues from cerebral I/R mice showed decreased TRPC1 expression. Similarly, TRPC1 expression was reduced in HT22 cells upon exposure to OGD/R treatment, followed by decreased Ca2+ influx. However, TRPC1 overexpression reversed the OGD/R-induced decrease in [Ca2+]i. TRPC1 knockout significantly exacerbated I/R-induced brain infarction, edema, neurological severity score, memory impairment, neurological deficits, and oxidative stress. In contrast, TRPC1 upregulation inhibited the increase in reactive oxygen species (ROS) generation induced by OGD/R. Analysis of key subunits of the Nox family and mitochondrial ROS revealed that the effects of TRPC1 downregulation on oxidative stress were associated with activation of Nox4-containing NADPH oxidase. TRPC1 interacted with Nox4 and facilitated Nox4 protein degradation under OGD/R conditions. In addition, TRPC1 inhibition potentiated the OGD/R-induced translocation of p47phox and p67phox as well as the interaction between Nox4 and p47phox or p67phox, whereas TRPC1 overexpression had the opposite effects. Conclusion: TRPC1 deficiency potentiates ROS generation via Nox4-containing NADPH oxidase, which exacerbates cerebral I/R injury. TRPC1 may be a promising molecular target for the treatment of stroke.

Background/Aims: Ischemic stroke is still one of the leading debilitating diseases with high morbidity and mortality. NADPH oxidase (NOX)-derived reactive oxygen species (ROS) play an important role in cerebral ischemia/reperfusion (I/R) injury. However, the mechanism underlying the regulation of ROS generation is still not fully elucidated. This study aims to explore the role of transforming growth beta (TGF-β) signals in ROS generation. Methods: Sprague–Dawley rats were subjected to I/R injury, and PC-12 cells were challenged by hypoxia/reoxygenation (H/R) and/or treated with activin receptor-like kinase (ALK5) inhibitor Sb505124 or siRNA against ALK5. Brain damage was evaluated using neurological scoring, triphenyl tetrazolium chloride staining, hematoxylin and eosin staining, infarct volume measurement, TUNEL staining, and caspase-3 activity measurement. Expression of TGF-β and oxidative stress-related genes was analyzed by real-time polymerase chain reaction and Western blot; NOX activity and ROS level were measured using spectrophotometry and fluorescence microscopy, respectively. Results: I/R contributed to severe brain damage (impaired neurological function, brain infarction, tissue edema, apoptosis), TGF-β signaling activation (upregulation of ALK5, phosphorylation of SMAD2/3) and oxidative stress (upregulation of NOX2/4, rapid release of ROS [oxidative burst]). However, Sb505124 significantly reversed these alterations and protected rats against I/R injury. As in the animal results, H/R also contributed to TGF-β signaling activation and oxidative stress. Likewise, the inhibition of ALK5 or ALK5 knockdown significantly reversed these alterations in PC-12 cells. Other than ALK5 knockdown, ALK5 inhibition had no effect on the expression of ALK5 in PC-12 cells. Conclusions: Our studies demonstrated that TGF-β signaling activation is involved in the regulation of NOX2/NOX4 expression and exacerbates cerebral I/R injury.

Background/Aims: Nuclear erythroid 2-related factor-2 (Nrf2) is a major stress-response transcription factor that has been implicated in regulating ischemic angiogenesis. We investigated the effects of Nrf2 in regulating revascularization and modulating acute lung injury. Methods: The expression of Nrf2 and sirtuin1 (Sirt1) was assessed in lung tissue by western blotting and immunofluorescence staining after intestinal ischemia/reperfusion (IIR) in Nrf2–/– and wild-type (WT) mice. The involvement of Nrf2 in angiogenesis, cell viability, and migration was investigated in human pulmonary microvascular endothelial cells (PMVECs). Additionally, the influence of Nrf2 expression on NOX pathway activation was measured in PMVECs after oxygen–glucose deprivation/reoxygenation. Results: We found activation and nuclear accumulation of Nrf2 in lung tissue after IIR. Compared to IIR in WT mice, IIR in Nrf2–/– mice significantly enhanced leukocyte infiltration and collagen deposit, and inhibited endothelial cell marker CD31 expression. Nrf2 upregulation and translocation into the nucleus stimulated by Sirt1 overexpression exhibited remission of histopathologic changes and enhanced CD31 expression. Nrf2 knockdown repressed non-phagocytic cell oxidase 4 (NOX4), hypoxia-inducible factor (HIF-1α) and vascular endothelial growth factor (VEGF) expression after IIR. Nrf2 upregulation by Sirt1 enhances NOX4, HIF-1α and VEGF expression after IIR in WT mice. Furthermore, Nrf2 knockdown suppressed cell viability, capillary tube formation and cell migration in PMVECs after oxygen–glucose deprivation/reoxygenation and also inhibited NOX4, HIF-1 and VEGF expression. Moreover, NOX4 knockdown in PMVECs decreased the levels of VEGF, HIF-1α and angiogenesis. Conclusion: Nrf2 stimulation by Sirt1 plays an important role in sustaining angiogenic potential through NOX4-mediated gene regulation.

Background/Aims: Nonalcoholic steatohepatitis includes steatosis along with liver inflammation, hepatocyte injury and fibrosis. In this study, we investigated the protective role and the potential mechanisms of a traditional Chinese medicine ShenFu (SF) preparation in an in vitro hepatic steatosis model. Methods: In palmitic acid (PA)-induced murine hepatic AML12 cell injury, effects of SF preparation on cellular apoptosis and intracellular triglyceride (iTG) level were assessed using TUNEL and TG Colorimetric Assay. Reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) levels were measured using DCF and JC-1 assay. Cytokine levels were evaluated using ELISA assay. Immunoblot was used to compare the activation level of c-Jun N terminal kinase (JNK), NADPH oxidase (Nox4), and NFκB pathways. Results: Addition of SF preparation prevented PA-mediated increase of apoptosis and iTG as well as IL-8 and IL-6. In PA-treated cell, SF preparation reduced the level of Nox4 and ROS, while increasing the level of MMP and the expression of manganese superoxide dismutase (MnSOD) and catalase, indicating emendation of mitochondrial dysfunction. Nox4 inhibitor GKT137381 prevented PA-induced increase of ROS and apoptosis, while decreasing iTG slightly and not influencing the level of IL-8 and IL-6. SF preparation prevented PA-induced upregulation of phospho-JNK. JNK inhibitor SP600125 prevented PA-mediated increase of Nox4, IL-8, IL-6 and iTG. Nuclear translocation of NFκB/p65 was detected in PA-treated cells, which was prevented by SF preparation. An IκB degradation inhibitor, BAY11-7082, prevented PA-induced increase of IL-8 and IL-6 as well as iTG, whereas it only decreased ROS levels slightly and showed no influence on cellular apoptosis. Conclusion: SF preparation shows a beneficial role in prevention of hepatocyte injury by attenuating oxidative stress and cytokines production at least partially through inhibition of JNK/Nox4 and JNK/NFκB pathway, respectively.

Background/Aims: Elevated production of reactive oxygen species (ROS) is linked to endothelial dysfunction and is one of the key contributors to the pathogenesis of diabetic vascular complications. Emerging evidence has indicated that ellagic acid (EA), a polyphenol found in fruits and nuts, possesses numerous biological activities including radical scavenging. However, whether EA exerts a vasculo-protective effect via antioxidant mechanisms in blood vessels exposed to diabetic conditions remains unknown. Accordingly, the goal of this current study was to determine whether EA decreases vascular ROS production and thus ameliorates endothelial dysfunction in the diabetic milieu. Methods: Intact rat aortas and human aortic endothelial cells (HAEC) were stimulated with 30mM high glucose (HG) with and without EA co-treatment. Endothelium-dependent vasodilation was measured using a wire myograph. Gene and protein expression of non-phagocytic nicotinamide adenine dinucleotide phosphate (NADPH) oxidases 4 (NOX4) were detected using RT-PCR and western blotting, respectively. Oxidative stress was determined by measuring ROS levels using dihydroethidium (DHE) staining. Results: Intact aortas exposed to HG condition displayed exacerbated ROS production and impairment of endothelium-dependent vasodilation, characterizing endothelial dysfunction. These effects were markedly reduced with EA treatment. HG enhanced ROS production in HAEC, paralleled by increased ERK1/2 activation and NOX4 expression. EA treatment blunted the increase of ROS generation, ERK1/2 activation and decreased NOX4. Conclusions: EA significantly decreases endothelial ROS levels and ameliorates the impairment of vascular relaxation induced by HG. Our results suggest that EA exerts a vasculo-protective effect under diabetic conditions via an antioxidant effect that involves inhibition of ERK1/2 and downregulation of NOX4.

Background/Aims: Our previous studies have indicated that a novel endothelin receptor antagonist CPU0213 effectively normalized renal function in diabetic nephropathy. However, the molecular mechanisms mediating the nephroprotective role of CPU0213 remain unknown. Methods and Results: In the present study, we first detected the role of CPU0213 on apoptosis in human renal tubular epithelial cell (HK-2). It was shown that high glucose significantly increased the protein expression of Bax and decreased Bcl-2 protein in HK-2 cells, which was reversed by CPU0213. The percentage of HK-2 cells that showed Annexin V-FITC binding was markedly suppressed by CPU0213, which confirmed the inhibitory role of CPU0213 on apoptosis. Given the regulation of endothelin (ET) system to oxidative stress, we determined the role of redox signaling in the regulation of CPU0213 on apoptosis. It was demonstrated that the production of superoxide (O2-.) was substantially attenuated by CPU0213 treatment in HK-2 cells. We further found that CPU0213 dramatically inhibited expression of Nox4 protein, which gene silencing mimicked the role of CPU0213 on the apoptosis under high glucose stimulation. We finally examined the role of CPU0213 on ET-1 receptors and found that high glucose-induced protein expression of endothelin A and B receptors was dramatically inhibited by CPU0213. Conclusion: Taken together, these results suggest that this Nox4-dependenet O2- production is critical for the apoptosis of HK-2 cells in high glucose. Endothelin receptor antagonist CPU0213 has an anti-apoptosis role through Nox4-dependent O2-.production, which address the nephroprotective role of CPU0213 in diabetic nephropathy.

Background/Aims: The incidence of developing microvascular dysfunction is significantly higher in type 1 diabetic (T1D) patients. Hyperketonemia (acetoacetate, β-hydroxybutyrate) is frequently found along with hyperglycemia in T1D. Whether hyperketonemia per se contributes to the excess oxidative stress and cellular injury observed in T1D is not known. Methods: HUVEC were treated with ketones in the presence or absence of high glucose for 24 h. NOX4 siRNA was used to specifically knockdown NOX4 expression in HUVEC. Results: Ketones alone or in combination with high glucose treatment cause a significant increase in oxidative stress, ICAM-1, and monocyte adhesivity to HUVEC. Using an antisense approach, we show that ketone induced increases in ROS, ICAM-1 expression, and monocyte adhesion in endothelial cells were prevented in NOX4 knockdown cells. Conclusion: This study reports that elevated levels of ketones upregulate NOX, contributing to increased oxidative stress, ICAM-1 levels, and cellular dysfunction. This provides a novel biochemical mechanism that elucidates the role of hyperketonemia in the excess cellular injury in T1D. New drugs targeting inhibition of NOX seems promising in preventing higher risk of complications associated with T1D.

Background/Aims: High phosphate (Pi) levels and extracellular matrix (ECM) accumulation are associated with chronic kidney disease progression. However, how high Pi levels contribute to ECM accumulation in mesangial cells is unknown. The present study investigated the role and mechanism of high Pi levels in ECM accumulation in immortalized human mesangial cells (iHMCs). Methods: iHMCs were exposed to normal (0.9 mM) or increasing Pi concentrations (2.5 and 5 mM) with or without diferent blockers or activators. NOX4, phosphorylated AMPK (p-AMPK), phosphorylated SMAD3 (p-SMAD3), fibronectin (F/N), collagen IV (C-IV) and alpha-smooth muscle actin (α-SMA) expression was assessed via western blot and immunofluorescence. Lucigenin-enhanced chemiluminescence, and dihydroethidium (DHE) assessed NADPH oxidase activity and superoxide (SO), respectively. Results: In iHMCs, a Pi transporter blocker (PFA) abrogated high Pi-induced AMPK inactivation, increase in NADPH oxidase-induced reactive oxygen species (ROS) levels, NOX4, p-SMAD3, α-SMA and C-IV expression. AMPK activation by AICAR, NOX4 silencing or NADPH oxidase blocker prevented high Pi-induced DHE levels, p-SMAD3, F/N, C-IV and α-SMA expression. Conclusion: AMPK inactivation with NOX4-induced ROS formation and transforming growth factor ß-1 (TGFß-1) signaling activation mediates high Pi-induced ECM accumulation in iHMCs. Maneuvers increasing AMPK or reducing NOX4 activity may contribute to renal protection under hyperphosphatemia.

Background/aims: Transient receptor potential cation channel 1 (TRPC1)-mediated the calcium (Ca2+) influx plays an important role in several brain disorders. However, the function of TRPC1 in ischemia/reperfusion (I/R)-induced neurological injury is unclear., Methods: Wild-type or TRPC1 knockout mice underwent middle cerebral artery occlusion for 90 min followed by 24 h of reperfusion. In an in vitro study, neuronal cells were treated with oxygen-glucose deprivation and reoxygenation (OGD/R) to mimic I/R. The intracellular Ca2+ concentration [Ca2+]i was measured by Fura 2-AM under a microscope. Cerebral infarct volume was measured by triphenyltetrazolium chloride staining. Neurological function was examined by neurological severity score, Morris water maze test, rotarod test and string test. Oxidative parameters were detected by malondialdehyde, glutathione peroxidase, and superoxide dismutase commercially available kits. The protein expression levels of TRPC1, Nox4, p22phox, p47phox, and p67phox were analyzed by western blotting., Results: Brain tissues from cerebral I/R mice showed decreased TRPC1 expression. Similarly, TRPC1 expression was reduced in HT22 cells upon exposure to OGD/R treatment, followed by decreased Ca2+ influx. However, TRPC1 overexpression reversed the OGD/R-induced decrease in [Ca2+]i. TRPC1 knockout significantly exacerbated I/R-induced brain infarction, edema, neurological severity score, memory impairment, neurological deficits, and oxidative stress. In contrast, TRPC1 upregulation inhibited the increase in reactive oxygen species (ROS) generation induced by OGD/R. Analysis of key subunits of the Nox family and mitochondrial ROS revealed that the effects of TRPC1 downregulation on oxidative stress were associated with activation of Nox4-containing NADPH oxidase. TRPC1 interacted with Nox4 and facilitated Nox4 protein degradation under OGD/R conditions. In addition, TRPC1 inhibition potentiated the OGD/R-induced translocation of p47phox and p67phox as well as the interaction between Nox4 and p47phox or p67phox, whereas TRPC1 overexpression had the opposite effects., Conclusion: TRPC1 deficiency potentiates ROS generation via Nox4-containing NADPH oxidase, which exacerbates cerebral I/R injury. TRPC1 may be a promising molecular target for the treatment of stroke., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Background/aims: Ischemic stroke is still one of the leading debilitating diseases with high morbidity and mortality. NADPH oxidase (NOX)-derived reactive oxygen species (ROS) play an important role in cerebral ischemia/reperfusion (I/R) injury. However, the mechanism underlying the regulation of ROS generation is still not fully elucidated. This study aims to explore the role of transforming growth beta (TGF-β) signals in ROS generation., Methods: Sprague-Dawley rats were subjected to I/R injury, and PC-12 cells were challenged by hypoxia/reoxygenation (H/R) and/or treated with activin receptor-like kinase (ALK5) inhibitor Sb505124 or siRNA against ALK5. Brain damage was evaluated using neurological scoring, triphenyl tetrazolium chloride staining, hematoxylin and eosin staining, infarct volume measurement, TUNEL staining, and caspase-3 activity measurement. Expression of TGF-β and oxidative stress-related genes was analyzed by real-time polymerase chain reaction and Western blot; NOX activity and ROS level were measured using spectrophotometry and fluorescence microscopy, respectively., Results: I/R contributed to severe brain damage (impaired neurological function, brain infarction, tissue edema, apoptosis), TGF-β signaling activation (upregulation of ALK5, phosphorylation of SMAD2/3) and oxidative stress (upregulation of NOX2/4, rapid release of ROS [oxidative burst]). However, Sb505124 significantly reversed these alterations and protected rats against I/R injury. As in the animal results, H/R also contributed to TGF-β signaling activation and oxidative stress. Likewise, the inhibition of ALK5 or ALK5 knockdown significantly reversed these alterations in PC-12 cells. Other than ALK5 knockdown, ALK5 inhibition had no effect on the expression of ALK5 in PC-12 cells., Conclusions: Our studies demonstrated that TGF-β signaling activation is involved in the regulation of NOX2/NOX4 expression and exacerbates cerebral I/R injury., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Background/aims: Nonalcoholic steatohepatitis includes steatosis along with liver inflammation, hepatocyte injury and fibrosis. In this study, we investigated the protective role and the potential mechanisms of a traditional Chinese medicine ShenFu (SF) preparation in an in vitro hepatic steatosis model., Methods: In palmitic acid (PA)-induced murine hepatic AML12 cell injury, effects of SF preparation on cellular apoptosis and intracellular triglyceride (iTG) level were assessed using TUNEL and TG Colorimetric Assay. Reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) levels were measured using DCF and JC-1 assay. Cytokine levels were evaluated using ELISA assay. Immunoblot was used to compare the activation level of c-Jun N terminal kinase (JNK), NADPH oxidase (Nox4), and NFκB pathways., Results: Addition of SF preparation prevented PA-mediated increase of apoptosis and iTG as well as IL-8 and IL-6. In PA-treated cell, SF preparation reduced the level of Nox4 and ROS, while increasing the level of MMP and the expression of manganese superoxide dismutase (MnSOD) and catalase, indicating emendation of mitochondrial dysfunction. Nox4 inhibitor GKT137381 prevented PA-induced increase of ROS and apoptosis, while decreasing iTG slightly and not influencing the level of IL-8 and IL-6. SF preparation prevented PA-induced upregulation of phospho-JNK. JNK inhibitor SP600125 prevented PA-mediated increase of Nox4, IL-8, IL-6 and iTG. Nuclear translocation of NFκB/p65 was detected in PA-treated cells, which was prevented by SF preparation. An IκB degradation inhibitor, BAY11-7082, prevented PA-induced increase of IL-8 and IL-6 as well as iTG, whereas it only decreased ROS levels slightly and showed no influence on cellular apoptosis., Conclusion: SF preparation shows a beneficial role in prevention of hepatocyte injury by attenuating oxidative stress and cytokines production at least partially through inhibition of JNK/Nox4 and JNK/NFκB pathway, respectively., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Background/aims: Nuclear erythroid 2-related factor-2 (Nrf2) is a major stress-response transcription factor that has been implicated in regulating ischemic angiogenesis. We investigated the effects of Nrf2 in regulating revascularization and modulating acute lung injury., Methods: The expression of Nrf2 and sirtuin1 (Sirt1) was assessed in lung tissue by western blotting and immunofluorescence staining after intestinal ischemia/reperfusion (IIR) in Nrf2-/- and wild-type (WT) mice. The involvement of Nrf2 in angiogenesis, cell viability, and migration was investigated in human pulmonary microvascular endothelial cells (PMVECs). Additionally, the influence of Nrf2 expression on NOX pathway activation was measured in PMVECs after oxygen-glucose deprivation/reoxygenation., Results: We found activation and nuclear accumulation of Nrf2 in lung tissue after IIR. Compared to IIR in WT mice, IIR in Nrf2-/- mice significantly enhanced leukocyte infiltration and collagen deposit, and inhibited endothelial cell marker CD31 expression. Nrf2 upregulation and translocation into the nucleus stimulated by Sirt1 overexpression exhibited remission of histopathologic changes and enhanced CD31 expression. Nrf2 knockdown repressed non-phagocytic cell oxidase 4 (NOX4), hypoxia-inducible factor (HIF-1α) and vascular endothelial growth factor (VEGF) expression after IIR. Nrf2 upregulation by Sirt1 enhances NOX4, HIF-1α and VEGF expression after IIR in WT mice. Furthermore, Nrf2 knockdown suppressed cell viability, capillary tube formation and cell migration in PMVECs after oxygen-glucose deprivation/reoxygenation and also inhibited NOX4, HIF-1 and VEGF expression. Moreover, NOX4 knockdown in PMVECs decreased the levels of VEGF, HIF-1α and angiogenesis., Conclusion: Nrf2 stimulation by Sirt1 plays an important role in sustaining angiogenic potential through NOX4-mediated gene regulation., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Background/aims: Elevated production of reactive oxygen species (ROS) is linked to endothelial dysfunction and is one of the key contributors to the pathogenesis of diabetic vascular complications. Emerging evidence has indicated that ellagic acid (EA), a polyphenol found in fruits and nuts, possesses numerous biological activities including radical scavenging. However, whether EA exerts a vasculo-protective effect via antioxidant mechanisms in blood vessels exposed to diabetic conditions remains unknown. Accordingly, the goal of this current study was to determine whether EA decreases vascular ROS production and thus ameliorates endothelial dysfunction in the diabetic milieu., Methods: Intact rat aortas and human aortic endothelial cells (HAEC) were stimulated with 30mM high glucose (HG) with and without EA co-treatment. Endothelium-dependent vasodilation was measured using a wire myograph. Gene and protein expression of non-phagocytic nicotinamide adenine dinucleotide phosphate (NADPH) oxidases 4 (NOX4) were detected using RT-PCR and western blotting, respectively. Oxidative stress was determined by measuring ROS levels using dihydroethidium (DHE) staining., Results: Intact aortas exposed to HG condition displayed exacerbated ROS production and impairment of endothelium-dependent vasodilation, characterizing endothelial dysfunction. These effects were markedly reduced with EA treatment. HG enhanced ROS production in HAEC, paralleled by increased ERK1/2 activation and NOX4 expression. EA treatment blunted the increase of ROS generation, ERK1/2 activation and decreased NOX4., Conclusions: EA significantly decreases endothelial ROS levels and ameliorates the impairment of vascular relaxation induced by HG. Our results suggest that EA exerts a vasculo-protective effect under diabetic conditions via an antioxidant effect that involves inhibition of ERK1/2 and downregulation of NOX4., (© 2017 The Author(s). Published by S. Karger AG, Basel.)