Targeting benign prostate hyperplasia treatments: AR/TGF-β/NOX4 inhibition by apocynin suppresses inflammation and proliferation

INTRODUCTION

Apocynin (Apo), an NADPH oxidase (NOX) inhibitor, has been widely used to treat various inflammatory diseases. However, the therapeutic effects of Apo on benign prostatic hyperplasia (BPH), a multifactorial disease associated with chronic inflammation and hormone imbalance, remain unknown.

OBJECTIVES

The link between androgen signaling, reactive oxygen species (ROS), and prostate cell proliferation may contribute to the pathogenesis of BPH; therefore, the aim of this study was to identify the specific signaling pathway involved and to demonstrate whether the anti-oxidant Apo plays a role in the prevention and treatment of BPH.

METHODS

Ingenuity pathway analysis and si-RNA transfection were conducted to demonstrate the androgen receptor (AR) and NOX4 linkage in BPH. Pathological markers of BPH were measured by H&E staining, immunoblotting, ELISA, qRT-PCR, and immunofluorescence to examine the effect of Apo. Rats stimulated with testosterone and BPH-1 cells were used as BPH models.

RESULTS

AR and NOX4 network-mediated oxidative stress was upregulated in the BPH model. Next, we examined the effects of Apo on oxidative stress and chronic prostatic inflammation in BPH mouse models. In a testosterone-induced BPH rat model, Apo alleviated pathological prostate enlargement and suppressed androgen/AR signaling. Apo suppressed the upregulation of proinflammatory markers and promoted the expression of anti-oxidant factors. Furthermore, Apo regulated the TGF-β/Glut9/activin pathway and macrophage programming. In BPH-1 cells, Apo suppressed AR-mediated proliferation and upregulation of TGFB and NOX4 expression by alleviating oxidative stress. Apo activated anti-oxidant and anti-inflammatory systems and regulated macrophage polarization in BPH-1 cells. AR knockdown partially abolished the beneficial effects of Apo in prostate cells, indicating AR-dependent effects of Apo.

CONCLUSION

In contrast with existing BPH therapies, Apo may provide a new application for prostatic disease treatment, especially for BPH, by targeting the AR/TGF-β/NOX4 signaling pathway.

Ang-(1-7)/Mas axis ameliorates bleomycin-induced pulmonary fibrosis in mice via restoration of Nox4-Nrf2 redox homeostasis

Pulmonary fibrosis (PF) is a chronic, progressive interstitial lung disease characterized by diffuse alveolar inflammation, fibroblast differentiation, and the excessive deposition of extracellular matrix. During the progression of PF, redox imbalance caused by excessive reactive oxygen species (ROS) production can result in further destruction of lung tissue. At present, data on the role of NADPH oxidase-4 (Nox4)-nuclear factor erythroid 2-related factor 2 (Nrf2) redox imbalance in PF are limited. The angiotensin (1-7) [Ang-(1-7)]/Mas axis is a protective axis in the renin-angiotensin system (RAS) that exerts antifibrotic effects. Therefore, this study aimed to investigate the role of the Ang-(1-7)/Mas axis in PF and to explore its mechanism in depth. The results revealed that the Ang-(1-7)/Mas axis inhibited TGF-β1-induced lung fibroblast differentiation, inflammation and fibrosis in bleomycin (BLM)-treated lung tissue. A mechanistic study suggested that the Ang-(1-7)/Mas axis may restore Nox4-Nrf2 redox homeostasis by upregulating the level of p62, reducing oxidative stress and the inflammatory response and thus delaying the progression of lung fibrosis. This study provides a theoretical basis for exploring the mechanisms of PF and therapeutic targets for PF.

Neuronal NADPH oxidase is required for neurite regeneration of Aplysia bag cell neurons

NADPH oxidase (Nox), a major source of reactive oxygen species (ROS), is involved in neurodegeneration after injury and disease. Nox is expressed in both neuronal and non-neuronal cells and contributes to an elevated ROS level after injury. Contrary to the well-known damaging effect of Nox-derived ROS in neurodegeneration, recently a physiological role of Nox in nervous system development including neurogenesis, neuronal polarity, and axonal growth has been revealed. Here, we tested a role for neuronal Nox in neurite regeneration following mechanical transection in cultured Aplysia bag cell neurons. Using a novel hydrogen peroxide (H2 O2 )-sensing dye, 5'-(p-borophenyl)-2'-pyridylthiazole pinacol ester (BPPT), we found that H2 O2 levels are elevated in regenerating growth cones following injury. Redistribution of Nox2 and p40phox in the growth cone central domain suggests Nox2 activation after injury. Inhibiting Nox with the pan-Nox inhibitor celastrol reduced neurite regeneration rate. Pharmacological inhibition of Nox is correlated with reduced activation of Src2 tyrosine kinase and F-actin content in the growth cone. Taken together, these findings suggest that Nox-derived ROS regulate neurite regeneration following injury through Src2-mediated regulation of actin organization in Aplysia growth cones.

Effects and Mechanisms of Peritoneal Resuscitation on Acute Kidney Injury After Severe Burns in Rats

INTRODUCTION

Acute kidney injury (AKI) is a common complication in severe burn patients with poor prognosis and high mortality. Reduced kidney perfusion induced by the decreased effective circulating blood volume after severe burn is a common cause of AKI. Routine intravenous resuscitation (IR) is difficult or delayed in extreme conditions such as war and disaster sites. Peritoneal resuscitation (PR) is a simple, rapid resuscitation strategy via a puncture in the abdominal wall. This study investigated whether PR is a validated resuscitation strategy for AKI after severe burns in rats and explored its mechanisms.

MATERIALS AND METHODS

Eighty Sprague-Dawley rats were randomized into four groups: (1) sham group; (2) IR group, which was characterized by the full thickness burn of 50% of the total body surface area received IR immediately post-injury; (3) early PR group, in which rats with the same burn model received PR immediately post-injury; and (4) delayed resuscitation (DR) group, in which rats with the same burn model received no resuscitation within 3-hour post-injury. PR and DR groups animals received IR after 3-hour post-injury. The survival rate, mean arterial pressure, renal histopathology, renal function, indicators of renal injury, and renal hypoxia-inducible factor-1α and NADPH oxidase 4 (NOX4) proteins of rats were measured at 3 h, 12 h, and 24 h post-injury.

RESULTS

Compared with rats in the DR group, rats in the PR group had a significantly improved survival rate (100% vs. 58.3% at 24 h, P = 0.0087), an increased mean arterial pressure (92.6 ± 6.6 vs. 65.3 ± 10.7, 85.1 ± 5.7 vs. 61.1 ± 6.9, 90.1 ± 8.7 vs. 74.9 ± 7.4 mmHg, at 3 h, 12 h, and 24 h, P < 0.01), a reduced renal water content rate (51.6% ± 5.0% vs. 70.1% ± 6.8%, 57.6% ± 7.7% vs. 69.5% ± 8.7%, at 12 h and 24 h, P < 0.01), attenuated histopathological damage, reduced serum creatinine expression (36.36 ± 4.27 vs. 49.98 ± 2.42, 52.29 ± 4.31 vs. 71.32 ± 5.2, 45.25 ± 2.55 vs. 81.15 ± 6.44 μmol/L, at 3 h, 12 h, and 24 h, P < 0.01) and BUN expression (7.62 ± 0.30 vs. 10.80 ± 0.58, 8.61 ± 0.32 vs. 28.58 ± 1.99, 8.09 ± 0.99 vs. 20.95 ± 1.02 mmol/L, at 3 h, 12 h, and 24 h, P < 0.01), increased kidney injury markers neutrophil gelatinase-associated lipocalin expression (95.09 ± 7.02 vs. 101.75 ± 6.23, 146.77 ± 11.54 vs. 190.03 ± 9.87, 112.79 ± 15.8 vs. 194.43 ± 11.47 ng/mL, at 3 h, 12 h, and 24 h, P < 0.01) and cystatin C expression (0.185 ± 0.006 vs. 0.197 ± 0.006, 0.345 ± 0.036 vs. 0.382 ± 0.013, 0.297 ± 0.012 vs. 0.371 ± 0.028 ng/mL, at 3 h, 12 h, and 24 h, P < 0.01), and reduced renal hypoxia-inducible factor-1α and NADPH oxidase 4 protein expression (P < 0.01). There was no significant difference between rats in the PR group and the IR group in the above indicators.

CONCLUSIONS

Early PR could protect severe burn injury rats from AKI. It may be an alternative resuscitation strategy in severe burn injury when IR cannot be achieved.

Adipocyte-Derived Exosomal NOX4-Mediated Oxidative Damage Induces Premature Placental Senescence in Obese Pregnancy

Background

A recent study has reported that maternal obesity is linked to placental oxidative damage and premature senescence. NADPH oxidase 4 (NOX4) is massively expressed in adipose tissue, and its induced reactive oxygen species have been found to contribute to cellular senescence. While, whether, in obese pregnancy, adipose tissue-derived NOX4 is the considerable cause of placental senescence remained elusive.

Methods

This study collected term placentas from obese and normal pregnancies and obese pregnant mouse model was constructed by a high fat diet to explore placental senescence. Furthermore, adipocyte-derived exosomes were isolated from primary adipocyte medium of obese and normal pregnancies to examine their effect on placenta functions in vivo and vitro.

Results

The placenta from the obese group showed a significant increase in placental oxidative damage and senescence. Exosomes from obese adipocytes contained copies of NOX4, and when cocultured with HTR8/SVneo cells, they induced severe oxidative damage, cellular senescence, and suppressed proliferation and invasion functions when compared with the control group. In vivo, adipocyte-derived NOX4-containing exosomes could induce placental oxidative damage and senescence, ultimately leading to adverse pregnancy outcomes.

Conclusion

In obesity, adipose tissue can secrete exosomes containing NOX4 which can be delivered to trophoblast resulting in severe DNA oxidative damage and premature placental senescence, ultimately leading to adverse pregnancy outcomes.

The selective NOX4 inhibitor GLX7013159 decreases blood glucose concentrations and human beta-cell apoptotic rates in diabetic NMRI nu/nu mice transplanted with human islets

NADPH oxidase 4 (NOX4) inhibition has been reported to mitigate diabetes-induced beta-cell dysfunction and improve survival in vitro, as well as counteract high-fat diet-induced glucose intolerance in mice. We investigated the antidiabetic effects of the selective NOX4 inhibitor GLX7013159 in vivo in athymic diabetic mice transplanted with human islets over a period of 4 weeks. The GLX7013159-treated mice achieved lower blood glucose and water consumption throughout the treatment period. Furthermore, GLX7013159 treatment resulted in improved insulin and c-peptide levels, better insulin secretion capacity, as well as in greatly reduced apoptotic rates of the insulin-positive human cells, measured as colocalization of insulin and cleaved caspase-3. We conclude that the antidiabetic effects of NOX4 inhibition by GLX7013159 are observed also during a prolonged study period in vivo and are likely to be due to an improved survival and function of the human beta-cells.

NOX2 and NOX4 control mitochondrial function in chronic myeloid leukaemia

Cancer cells are characterised by an elevated metabolic plasticity and enhanced production of reactive oxygen species (ROS), two features acknowledged as hallmarks in cancer, with a high translational potential to the therapeutic setting. These aspects, that have been traditionally studied separately, are in fact intimately intermingled. As part of their transforming activity, some oncogenes stimulate rewiring of metabolic processes, whilst simultaneously promoting increased production of intracellular ROS. In this scenario the latest discoveries suggest the relevance of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) to connect ROS production and metabolic control. Here we have analysed the relevance of NOX2 and NOX4 in the regulation of metabolism in chronic myeloid leukaemia (CML), a neoplasia driven by the expression of the breakpoint cluster region-Abelson fusion oncogene (BCR-ABL). Silencing of NOX2 enhances glycolysis and oxidative phosphorylation rates, together with an enhanced production of mitochondrial ROS and a decrease in mitochondrial DNA copy number, which reflects mitochondrial dysfunction. NOX4 expression was upregulated upon NOX2 silencing, and this was required to alter mitochondrial function. Our results support the relevance of NOX2 to regulate metabolism-related signalling pathways downstream of BCR-ABL. Overall we show that NOX2, through the regulation of NOX4 expression, controls metabolism and mitochondrial function in CML cells. This notion was confirmed by transcriptomic analyses, that strongly relate both NOX isoforms with metabolism regulation in CML.

Pre-clinical evidence of a dual NADPH oxidase 1/4 inhibitor (setanaxib) in liver, kidney and lung fibrosis

Fibrosis describes a dysregulated tissue remodelling response to persistent cellular injury and is the final pathological consequence of many chronic diseases that affect the liver, kidney and lung. Nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase (NOX) enzymes produce reactive oxygen species (ROS) as their primary function. ROS derived from NOX1 and NOX4 are key mediators of liver, kidney and lung fibrosis. Setanaxib (GKT137831) is a first-in-class, dual inhibitor of NOX1/4 and is the first NOX inhibitor to progress to clinical trial investigation. The anti-fibrotic effects of setanaxib in liver, kidney and lung fibrosis are supported by multiple lines of pre-clinical evidence. However, despite advances in our understanding, the precise roles of NOX1/4 in fibrosis require further investigation. Additionally, there is a translational gap between the pre-clinical observations of setanaxib to date and the applicability of these to human patients within a clinical setting. This narrative review critically examines the role of NOX1/4 in liver, kidney and lung fibrosis, alongside the available evidence investigating setanaxib as a therapeutic agent in pre-clinical models of disease. We discuss the potential clinical translatability of this pre-clinical evidence, which provides rationale to explore NOX1/4 inhibition by setanaxib across various fibrotic pathologies in clinical trials involving human patients.

The Protective Effect of Vitexin Compound B-1 on Rat Cerebral I/R Injury through a Mechanism Involving Modulation of miR-92b/NOX4 Pathway

BACKGROUND

Recent studies have uncovered that vitexin compound B-1 (VB-1) can protect neurons against hypoxia/reoxygenation (H/R)-induced oxidative injury through suppressing NOX4 expression.

OBJECTIVE

The aims of this study are to investigate whether VB-1 can protect the rat brain against ischemia/ reperfusion (I/R) injury and whether its effect on NOX4 expression is related to modulation of certain miRNAs expression.

METHODS

Rats were subjected to 2 h of cerebral ischemia followed by 24 h of reperfusion to establish an I/R injury model, which showed an increase in neurological deficit score and infarct volume concomitant with an upregulation of NOX4 expression, increase in NOX activity, and downregulation of miR-92b.

RESULTS

Administration of VB-1 reduced I/R cerebral injury accompanied by a reverse in NOX4 and miR-92b expression. Similar results were achieved in a neuron H/R injury model. Next, we evaluated the association of miR-92b with NOX4 by its mimics in the H/R model. H/R treatment increased neurons apoptosis concomitant with an upregulation of NOX4 and NOX activity while downregulation of miR-92b. All these effects were reversed in the presence of miR-92b mimics, confirming the function of miR-92b in suppressing NOX4 expression.

CONCLUSION

We conclude the protective effect of VB-1 against rat cerebral I/R injury through a mechanism involving modulation of miR-92b/NOX4 pathway.

[Effect of electroacupuncture combined with Zhuang-medicine-thread moxibustion on oxidative stress in gastric antrum of diabetic gastroparesis rats]

OBJECTIVE

To observe the effect of electroacupuncture (EA) combined with Zhuang-medicine-thread moxibustion on oxidative stress-related indicators in diabetic gastroparesis (DGP) rats, so as to explore its mechanism underlying improvement of DGP.

METHODS

Male SD rats were randomly divided into normal, model, medication, EA, Zhuang-medicine-thread moxibustion (moxibustion) and EA+Zhuang-medicine-thread moxibustion (combination) groups (15 rats in each group). The DGP model was established by intraperitoneal injection of streptozotocin (STZ). Rats of the medication group were treated by gavage of 0.15 mg/mL mosapride citrate suspension（10 mL/kg）. EA (10 Hz/50 Hz, 2 mA, 20 min) or Zhuang-medicine-thread moxibustion (3 cones) was applied to "Zhongwan" (CV12), bilateral "Neiguan" (PC6) and bilateral "Sanyinjiao" (SP6) of the related groups, once a day for 3 weeks. The body weight, blood glucose, gastric emptying rate and intestinal propulsion rate of rats were measured. The serum malondialdehyde (MDA) content was measured by thiobarbituric acid method, the serum supero-xide dismutase (SOD) activity was measured by xanthine oxidase method, and the serum reactive oxygen species (ROS) activity was detected by ELISA. HE staining was used to observe the pathological changes of gastric antrum. The expression of heme oxygenase-1 (HO-1), nuclear factor erythroid 2-related factor 2 (Nrf2), nicotin-amide adenine dinucleotide phosphate oxidases (NOX4), peroxisome proliferators activated receptor-gamma coactivator 1α(PGC-1α) proteins and mRNAs in gastric antrum was detected by Western blot and real-time quantitative PCR, respectively.

RESULTS

Compared with the normal group, the body weight, gastric emptying rate, intestinal propulsion rate, serum SOD activity, the expressions of HO-1, PGC-1α, total Nrf2 proteins and mRNAs, and Nrf2 nuclear translocation in gastric antrum were decreased (P<0.01), while the blood glucose, serum MDA content and ROS activity, NOX4 protein and mRNA expressions in gastric antrum were increased (P<0.01) in the model group. Compared with the model group, the blood glucose was decreased in the EA, moxibustion and combination groups (P<0.01); the body weight, gastric emptying rate, intestinal propulsion rate, and the expressions of HO-1 and PGC-1α mRNAs in gastric antrum were all increased in the four treatment groups (P<0.01, P<0.05), while the serum MDA content and ROS activity, NOX4 protein and mRNA expressions in gastric antrum were all decreased (P<0.01); the serum SOD activity and total Nrf2 protein expression in gastric antrum were increased in medication, moxibustion and combination groups (P<0.01, P<0.05); the expressions of HO-1 and PGC-1α proteins, and Nrf2 nuclear translocation in gastric antrum were increased in medication and combination groups (P<0.05, P<0.01); the expression of Nrf2 mRNA was increased in the medication, EA and combination groups (P<0.01, P<0.05). Compared with the combination group, the body weight, gastric emptying rate and intestine propulsion rate were decreased in the medication, EA and moxibustion groups(P<0.01, P<0.05), and the blood glucose increased (P<0.01); the serum MDA content and ROS activity, NOX4 protein and mRNA expressions in gastric antrum were increased (P<0.01, P<0.05), serum SOD activity, and the expressions of total Nrf2 protein, PGC-1α protein and mRNA, HO-1 mRNA in gastric antrum were decreased (P<0.01, P<0.05) in the EA and moxibustion groups; the expression of Nrf2 mRNA was decreased in the moxibustion group (P<0.05). HE staining showed a large number of inflammatory cell infiltration in the lamina propria and submucosa, and the gastric glands in the lamina propria were significantly expanded, the submucosa was severely edematous in the model group, which were relative milder in the four treatment groups.

CONCLUSION

EA combined with Zhuang-medicine-thread moxibustion can effectively improve the activity of antioxidant enzymes, reduce the production of lipid peroxide, and regulate the expression of antioxidant related proteins and genes, which may be one of the mechanisms in treating DGP.

Evolutionary and structural analyses of the NADPH oxidase family in eukaryotes reveal an initial calcium dependency

Reactive oxygen species are unstable molecules generated by the partial reduction of dioxygen. NADPH oxidases are a ubiquitous family of enzymes devoted to ROS production. They fuel an array of physiological roles in different species and are chemically demanding enzymes requiring FAD, NADPH and heme prosthetic groups in addition to either calcium or a various number of cytosolic mediators for activity. These activating partners are exclusive components that partition and distinguish the NOX members from one another. To gain insight into the evolution of these activating mechanisms, and in general in their evolutionary history, we conducted an in-depth phylogenetic analysis of the NADPH oxidase family in eukaryotes. We show that all characterized NOXs share a common ancestor, which comprised a fully formed catalytic unit. Regarding the activation mode, we identified calcium-dependency as the earliest form of NOX regulation. The protein-protein mode of regulation would have evolved more recently by gene-duplication with the concomitant loss of the EF-hands motif region. These more recent events generated the diversely activated NOX systems as observed in extant animals and fungi.

Targeting Hydrogen Sulfide Modulates Dexamethasone-Induced Muscle Atrophy and Microvascular Rarefaction, through Inhibition of NOX4 and Induction of MGF, M2 Macrophages and Endothelial Progenitors

Long-term use of Glucocorticoids produces skeletal muscle atrophy and microvascular rarefaction. Hydrogen sulfide (H2S) has a potential role in skeletal muscle regeneration. However, the mechanisms still need to be elucidated. This is the first study to explore the effect of Sodium hydrosulfide (NaHS) H2S donor, against Dexamethasone (Dex)-induced soleus muscle atrophy and microvascular rarefaction and on muscle endothelial progenitors and M2 macrophages. Rats received either; saline, Dex (0.6 mg/Kg/day), Dex + NaHS (5 mg/Kg/day), or Dex + Aminooxyacetic acid (AOAA), a blocker of H2S (10 mg/Kg/day) for two weeks. The soleus muscle was examined for contractile properties. mRNA expression for Myostatin, Mechano-growth factor (MGF) and NADPH oxidase (NOX4), HE staining, and immunohistochemical staining for caspase-3, CD34 (Endothelial progenitor marker), vascular endothelial growth factor (VEGF), CD31 (endothelial marker), and CD163 (M2 macrophage marker) was performed. NaHS could improve the contractile properties and decrease oxidative stress, muscle atrophy, and the expression of NOX4, caspase-3, Myostatin, VEGF, and CD31 and could increase the capillary density and expression of MGF with a significant increase in expression of CD34 and CD163 as compared to Dex group. However, AOAA worsened the studied parameters. Therefore, H2S can be a promising target to attenuate muscle atrophy and microvascular rarefaction.

Backstage players of fibrosis: NOX4, mTOR, HDAC, and S1P; companions of TGF-β

The fibrotic process could be easily defined as a pathological excess of extracellular matrix deposition, leading to disruption of tissue architecture and eventually loss of function; however, this process involves a complex network of several signal transduction pathways. Virtually almost all organs could be affected by fibrosis, the most affected are the liver, lung, skin, kidney, heart, and eyes; in all of them, the transforming growth factor-beta (TGF-β) has a central role. The canonical and non-canonical signal pathways of TGF-β impact the fibrotic process at the cellular and molecular levels, inducing the epithelial-mesenchymal transition (EMT) and the induction of profibrotic gene expression with the consequent increase in proteins such as alpha-smooth actin (α-SMA), fibronectin, collagen, and other extracellular matrix proteins. Recently, it has been reported that some molecules that have not been typically associated with the fibrotic process, such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4), mammalian target of rapamycin (mTOR), histone deacetylases (HDAC), and sphingosine-1 phosphate (S1P); are critical in its development. In this review, we describe and discuss the role of these new players of fibrosis and the convergence with TGF-β signaling pathways, unveiling new insights into the panorama of fibrosis that could be useful for future therapeutic targets.

C-C motif ligand 8 promotes atherosclerosis via NADPH oxidase 2/reactive oxygen species-induced endothelial permeability increase

Chemokines have been reported to play important roles in atherosclerotic development. Recently, we found C-C motif ligand 8 (CCL8), a rarely studied chemokine in atherosclerosis, was highly expressed in the endothelium of advanced human carotid plaques. We hypothesized whether CCL8 promotes atherosclerosis through endothelial dysfunction. Apolipoprotein E-deficient mice under the Western diet were used to construct atherosclerosis models. Adeno-associated viruses (AAV) with CCL8 and the CCL8-antibody were injected into mice respectively to conduct CCL8 overexpression and suppression. The results showed that atherosclerotic lesions were significantly increased in the AAV-CCL8 group, while, lesions in the aortic sinus were reduced in the CCL8-antibody group. With CCL8 treatment (200 ng/ml, 24 h) in vitro, the permeability of human aortic endothelial cells (HAECs) increased and the expression of junctional proteins Zonula occluden-1, and Vascular endothelial cadherin were decreased. This effect was dependent on reactive oxygen species (ROS) generation, which could be blocked by l-Ascorbic acid and Apocynin. Results showed that NADPH oxidase 2 (NOX2) expression also increased with CCL8 stimulation and the ROS, and permeability increase of HAECs could be inhibited when NOX2 interfered with the specific siRNA. Additionally, we further found ERK1/2, PI3K-AKT, and NF-κB pathways were involved in the activation of CCL8. Our results indicated that CCL8 might also play important roles in atherosclerosis and this effect, at least in part, was caused by NOX2/ROS-induced endothelial permeability increase. This study might contribute to a deeper understanding of the connection between chemokines and atherosclerosis.

NADPH Oxidases Are Required for Full Platelet Activation In Vitro and Thrombosis In Vivo but Dispensable for Plasma Coagulation and Hemostasis

OBJECTIVE

Using 3KO (triple NOX [NADPH oxidase] knockout) mice (ie, NOX1-/-/NOX2-/-/NOX4-/-), we aimed to clarify the role of this family of enzymes in the regulation of platelets in vitro and hemostasis in vivo. Approach and Results: 3KO mice displayed significantly reduced platelet superoxide radical generation, which was associated with impaired platelet aggregation, adhesion, and thrombus formation in response to the key agonists collagen and thrombin. A comparison with single-gene knockouts suggested that the phenotype of 3KO platelets is the combination of the effects of the genetic deletion of NOX1 and NOX2, while NOX4 does not show any significant function in platelet regulation. 3KO platelets displayed significantly higher levels of cGMP-a negative platelet regulator that activates PKG (protein kinase G). The inhibition of PKG substantially but only partially rescued the defective phenotype of 3KO platelets, which are responsive to both collagen and thrombin in the presence of the PKG inhibitors KT5823 or Rp-8-pCPT-cGMPs, but not in the presence of the NOS (NO synthase) inhibitor L-NG-monomethyl arginine. In vivo, triple NOX deficiency protected against ferric chloride-driven carotid artery thrombosis and experimental pulmonary embolism, while hemostasis tested in a tail-tip transection assay was not affected. Procoagulatory activity of platelets (ie, phosphatidylserine surface exposure) and the coagulation cascade in platelet-free plasma were normal.

CONCLUSIONS

This study indicates that inhibiting NOXs has strong antithrombotic effects partially caused by increased intracellular cGMP but spares hemostasis. NOXs are, therefore, pharmacotherapeutic targets to develop new antithrombotic drugs without bleeding side effects.

NOD1 activation induces oxidative stress via NOX1/4 in adipocytes

Activation of innate immune components promotes cell autonomous inflammation in adipocytes. Oxidative stress links pattern recognition receptor-mediated detection of inflammatory ligands and the immune response. Reactive oxygen species (ROS) may mediate the effect of nucleotide-binding oligomerization domain protein-1 (NOD1) activation on inflammation in adipocytes. Here, we define the potential role of NADPH oxidase (NOX)-derived ROS in NOD1-mediated inflammatory response in adipocytes. Differentiated 3T3-L1 adipocytes were treated with NOD1 activating ligand D-gamma-Glu-meso-diaminopimelic acid (iE-DAP) to evaluate the oxidative stress and contribution of NOX as source of intracellular ROS. NOD1 activation potently induced ROS generation in 3T3-L1 adipocytes. Of the NOX family members, expression of NOX1 and NOX4 was increased upon NOD1 activation, in a PKCδ-dependent manner. siRNA-mediated down-regulation of NOX1 or NOX4 inhibited NOD1-mediated ROS production and increased the expression of antioxidant defense enzyme catalase and superoxide dismutase (SOD). siRNA-mediated lowering of NOX1 or NOX4 also suppressed NOD1-mediated activation of JNK1/2 and NF-κB, and consequent activation of inflammatory response in 3T3-L1 adipocytes. In summary, our findings demonstrate that NOD1 activation provokes oxidative stress in adipocytes via NOX1/4 and that oxidative stress, at least in part, contributes to induction of inflammatory response. Defining the source of ROS after immune response engagement may lead to new therapeutic strategies for adipose tissue inflammation.

[Resveratrol inhibits hypoxia-induced oxidative stress and proliferation in pulmonary artery smooth muscle cells through the HIF-1α/NOX4/ROS signaling pathway]

The purpose of the present study was to determine the effects of resveratrol on hypoxia-induced oxidative stress and proliferation in pulmonary artery smooth muscle cells (PASMCs) and the underlying mechanism. Primary rat PASMCs were isolated and cultured in vitro and pretreated with different concentrations of resveratrol (10, 20, and 40 µmol/L) or the NADPH oxidase (NOX) inhibitor VAS2870 (10 µmol/L) for 0.5 h. The cells were then cultured under normoxia (21% O₂, 5% CO₂) or hypoxia (2% O₂, 5% CO₂) for 24 h. The proliferation of cells was measured using the CCK-8 method and the expression of proliferating cell nuclear antigen (PCNA). The production of reactive oxygen species (ROS) was detected by DCFH-DA. The expression of rat NOX1, NOX4 and hypoxia inducible factor 1α (HIF-1α) was detected by real-time RT-PCR and Western blotting assays. The related signaling pathways were determined using the small interference RNAs (siRNAs) specifically targeting Hif-1α and Nox4. The results showed that resveratrol and VAS2870 significantly inhibited hypoxia-induced cell proliferation and ROS production in rat PASMCs. Resveratrol also effectively prevented hypoxia-induced increase of HIF-1α protein levels and NOX4 up-regulation, but had little effect on NOX1. After the knocking down of Hif-1α or Nox4 with siRNAs, hypoxia-induced cell proliferation and ROS accumulation were significantly decreased, and both were further inhibited by resveratrol treatment. These results suggest that resveratrol inhibits hypoxia-induced oxidative stress and cell proliferation in rat PASMCs possibly through blocking the HIF-1α/NOX4/ROS pathway.

NOX4 Inhibition Potentiates Immunotherapy by Overcoming Cancer-Associated Fibroblast-Mediated CD8 T-cell Exclusion from Tumors

Determining mechanisms of resistance to αPD-1/PD-L1 immune-checkpoint immunotherapy is key to developing new treatment strategies. Cancer-associated fibroblasts (CAF) have many tumor-promoting functions and promote immune evasion through multiple mechanisms, but as yet, no CAF-specific inhibitors are clinically available. Here we generated CAF-rich murine tumor models (TC1, MC38, and 4T1) to investigate how CAFs influence the immune microenvironment and affect response to different immunotherapy modalities [anticancer vaccination, TC1 (HPV E7 DNA vaccine), αPD-1, and MC38] and found that CAFs broadly suppressed response by specifically excluding CD8+ T cells from tumors (not CD4+ T cells or macrophages); CD8+ T-cell exclusion was similarly present in CAF-rich human tumors. RNA sequencing of CD8+ T cells from CAF-rich murine tumors and immunochemistry analysis of human tumors identified significant upregulation of CTLA-4 in the absence of other exhaustion markers; inhibiting CTLA-4 with a nondepleting antibody overcame the CD8+ T-cell exclusion effect without affecting Tregs. We then examined the potential for CAF targeting, focusing on the ROS-producing enzyme NOX4, which is upregulated by CAF in many human cancers, and compared this with TGFβ1 inhibition, a key regulator of the CAF phenotype. siRNA knockdown or pharmacologic inhibition [GKT137831 (Setanaxib)] of NOX4 "normalized" CAF to a quiescent phenotype and promoted intratumoral CD8+ T-cell infiltration, overcoming the exclusion effect; TGFβ1 inhibition could prevent, but not reverse, CAF differentiation. Finally, NOX4 inhibition restored immunotherapy response in CAF-rich tumors. These findings demonstrate that CAF-mediated immunotherapy resistance can be effectively overcome through NOX4 inhibition and could improve outcome in a broad range of cancers. SIGNIFICANCE: NOX4 is critical for maintaining the immune-suppressive CAF phenotype in tumors. Pharmacologic inhibition of NOX4 potentiates immunotherapy by overcoming CAF-mediated CD8+ T-cell exclusion. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/9/1846/F1.large.jpg.See related commentary by Hayward, p. 1799.

Isoform-selective NADPH oxidase inhibitor panel for pharmacological target validation

Dysfunctional reactive oxygen species (ROS) signaling is considered an important disease mechanism. Therapeutically, non-selective scavenging of ROS by antioxidants, however, has failed in multiple clinical trials to provide patient benefit. Instead, pharmacological modulation of disease-relevant, enzymatic sources of ROS appears to be an alternative, more promising and meanwhile successfully validated approach. With respect to targets, the family of NADPH oxidases (NOX) stands out as main and dedicated ROS sources. Validation of the different NOX isoforms has been mainly through genetically modified rodent models and is lagging behind in other species. It is unclear whether the different NOX isoforms are sufficiently distinct to allow selective pharmacological modulation. Here we show for five widely used NOX inhibitors that isoform selectivity can be achieved, although individual compound specificity is as yet insufficient. NOX1 was most potently (IC₅₀) targeted by ML171 (0.1 μM); NOX2, by VAS2870 (0.7 μM); NOX4, by M13 (0.01 μM) and NOX5, by ML090 (0.01 μM). In addition, some non-specific antioxidant and assay artefacts may limit the interpretation of data, which included, surprisingly, the clinically advanced NOX inhibitor, GKT136901. In a human ischemic blood-brain barrier hyperpermeability model where genetic target validation is not an option, we provide proof-of-principle that pharmacological target validation for different NOX isoforms is possible by applying an inhibitor panel at IC₅₀ concentrations. Moreover, our findings encourage further lead optimization and development efforts for isoform-selective NOX inhibitors in different indications.

NADPH oxidase 1 mediates caerulein-induced pancreatic fibrosis in chronic pancreatitis

Inflammatory disorders of the pancreas are divided into acute (AP) and chronic (CP) forms. Both states of pancreatitis are a result of pro-inflammatory mediators, including reactive oxygen species (ROS). One of the sources of ROS is NADPH oxidase (Nox). The rodent genome encodes Nox1-4, Duox1 and Duox2. Our purpose was to assess the extent to which Nox enzymes contribute to the pathogenesis of both AP and CP using Nox-deficient mice. Using RT-PCR, Nox1 was found in both isolated mouse pancreatic acini and pancreatic stellate cells (PaSCs). Subsequently, mice with genetically deleted Nox1 were further studied and showed that the histo-morphologic characteristics of caerulein-induced CP, but not caerulein-induced AP, was ameliorated in Nox1 KO mice. We also found that the lack of Nox1 impaired caerulein-induced ROS generation in PaSCs. Using Western blotting, we found that AKT mediates the fibrotic effect of Nox1 in a mouse model of CP. We also found a decrease in phospho-ERK and p38MAPK levels in Nox1 KO mice with CP, but not with AP. Both CP-induced TGF-β up-regulation and NF-ĸB activation were impaired in pancreas from Nox1 KO mice. Western blotting indicated increases in proteins involved in fibrosis and acinar-to-ductal metaplasia in WT mice with CP. No change in those proteins were observed in Nox1 KO mice. The lack of Nox1 lowered mRNA levels of CP-induced matrix metalloproteinase MMP-9 and E-cadherin repressor Twist in PaSCs. CONCLUSION: Nox1-derived ROS in PaSCs mediate the fibrotic process of CP by activating the downstream redox-sensitive signaling pathways AKT and NF-ĸB, up-regulating MMP-9 and Twist, and producing α-smooth muscle actin and collagen I and III.

Targeting the Myofibroblastic Cancer-Associated Fibroblast Phenotype Through Inhibition of NOX4

Background

Cancer-associated fibroblasts (CAFs) are tumor-promoting and correlate with poor survival in many cancers, which has led to their emergence as potential therapeutic targets. However, effective methods to manipulate these cells clinically have yet to be developed.

Methods

CAF accumulation and prognostic significance in head and neck cancer (oral, n = 260; oropharyngeal, n = 271), and colorectal cancer (n = 56) was analyzed using immunohistochemistry. Mechanisms regulating fibroblast-to-myofibroblast transdifferentiation were investigated in vitro using RNA interference/pharmacological inhibitors followed by polymerase chain reaction (PCR), immunoblotting, immunofluorescence, and functional assays. RNA sequencing/bioinformatics and immunohistochemistry were used to analyze NAD(P)H Oxidase-4 (NOX4) expression in different human tumors. NOX4's role in CAF-mediated tumor progression was assessed in vitro, using CAFs from multiple tissues in Transwell and organotypic culture assays, and in vivo, using xenograft (n = 9-15 per group) and isograft (n = 6 per group) tumor models. All statistical tests were two-sided.

Results

Patients with moderate/high levels of myofibroblastic-CAF had a statistically significant decrease in cancer-specific survival rates in each cancer type analyzed (hazard ratios [HRs] = 1.69-7.25, 95% confidence intervals [CIs] = 1.11 to 31.30, log-rank P ≤ .01). Fibroblast-to-myofibroblast transdifferentiation was dependent on a delayed phase of intracellular reactive oxygen species, generated by NOX4, across different anatomical sites and differentiation stimuli. A statistically significant upregulation of NOX4 expression was found in multiple human cancers (P < .001), strongly correlating with myofibroblastic-CAFs (r = 0.65-0.91, adjusted P < .001). Genetic/pharmacological inhibition of NOX4 was found to revert the myofibroblastic-CAF phenotype ex vivo (54.3% decrease in α-smooth muscle actin [α-SMA], 95% CI = 10.6% to 80.9%, P = .009), prevent myofibroblastic-CAF accumulation in vivo (53.2%-79.0% decrease in α-SMA across different models, P ≤ .02) and slow tumor growth (30.6%-64.0% decrease across different models, P ≤ .04).

Conclusions

These data suggest that pharmacological inhibition of NOX4 may have broad applicability for stromal targeting across cancer types.

Lycopene Inhibits Metastasis of Human Liver Adenocarcinoma SK-Hep-1 Cells by Downregulation of NADPH Oxidase 4 Protein Expression

NADPH oxidase 4 (NOX4), with the sole function to produce reactive oxygen species (ROS), can be a molecular target for disrupting cancer metastasis. Several studies have indicated that lycopene exhibited anti-metastatic actions in vitro and in vivo. However, the role of NOX4 in the anti-metastatic action of lycopene remains unknown. Herein, we first confirmed the anti-metastatic effect of lycopene (0.1-5 μM) on human liver adenocarcinoma SK-Hep-1 cells. We showed that lycopene significantly inhibited NOX4 protein expression, with the strongest inhibition of 64.3 ± 10.2% (P < 0.05) at 2.5 μM lycopene. Lycopene also significantly inhibited NOX4 mRNA expression, NOX activity, and intracellular ROS levels in SK-Hep-1 cells. We then determined the effects of lycopene on transforming growth factor β (TGF-β)-induced metastasis. We found that TGF-β (5 ng/mL) significantly increased migration, invasion, and adhesion activity, the intracellular ROS level, matrix metalloproteinase 9 (MMP-9) and MMP-2 activities, the level of NOX4 protein expression, and NOX activity. All these TGF-β-induced effects were antagonized by the incubation of SK-Hep-1 cells with lycopene (2.5 μM). Using transient transfection of siRNA against NOX4, we found that the downregulation of NOX4 could mimic lycopene by inhibiting cell migration and the activities of MMP-9 and MMP-2 during the incubation with or without TGF-β on SK-Hep-1 cells. The results demonstrate that the downregulation of NOX4 plays a crucial role in the anti-metastatic action of lycopene in SK-Hep-1 cells.

Eicosapentaenoic acid prevents arterial calcification in klotho mutant mice

BACKGROUND

The klotho gene was identified as an "aging-suppressor" gene that accelerates arterial calcification when disrupted. Serum and vascular klotho levels are reduced in patients with chronic kidney disease, and the reduced levels are associated with arterial calcification. Intake of eicosapentaenoic acid (EPA), an n-3 fatty acid, reduces the risk of fatal coronary artery disease. However, the effects of EPA on arterial calcification have not been fully elucidated. The aim of this study was to determine the effect of EPA on arterial calcification in klotho mutant mice.

METHODS AND RESULTS

Four-week-old klotho mutant mice and wild-type (WT) mice were given a diet containing 5% EPA (EPA food, klotho and WT: n = 12, each) or not containing EPA (control food, klotho and WT: n = 12, each) for 4 weeks. Calcium volume scores of thoracic and abdominal aortas assessed by computed tomography were significantly elevated in klotho mice after 4 weeks of control food, but they were not elevated in klotho mice after EPA food or in WT mice. Serum levels of EPA and resolvin E1, an active metabolite of EPA, in EPA food-fed mice were significantly increased compared to those in control food-fed mice. An oxidative stress PCR array followed by quantitative PCR revealed that NADPH oxidase-4 (NOX4), an enzyme that generates superoxide, gene expression was up-regulated in arterial smooth muscle cells (SMCs) of klotho mice. Activity of NOX was also significantly higher in SMCs of klotho mice than in those of WT mice. EPA decreased expression levels of the NOX4 gene and NOX activity. GPR120, a receptor of n-3 fatty acids, gene knockdown by siRNA canceled effects of EPA on NOX4 gene expression and NOX activity in arterial SMCs of klotho mice.

CONCLUSIONS

EPA prevents arterial calcification together with reduction of NOX gene expression and activity via GPR120 in klotho mutant mice.

Dipeptidyl peptidase-4 inhibitor gemigliptin protects against vascular calcification in an experimental chronic kidney disease and vascular smooth muscle cells

Although dipeptidyl peptidase-4 inhibitors, a class of antidiabetic drugs, have various pleiotropic effects, it remains undetermined whether gemigliptin has a beneficial effect on vascular calcification. Therefore, this study was performed to evaluate the effect of gemigliptin on vascular calcification in a rat model of adenine-induced chronic kidney disease and in cultured vascular smooth muscle cells. Gemigliptin attenuated calcification of abdominal aorta and expression of RUNX2 in adenine-induced chronic kidney disease rats. In cultured vascular smooth muscle cells, phosphate-induced increase in calcium content was reduced by gemigliptin. Gemigliptin reduced phosphate-induced PiT-1 mRNA expression, reactive oxygen species generation, and NADPH oxidase mRNA expression (p22phox and NOX4). The reduction of oxidative stress by gemigliptin was associated with the downregulation of phospho-PI3K/AKT expression. High phosphate increased the expression of frizzled-3 (FDZ3) and decreased the expression of dickkopf-related protein-1 (DKK-1) in the Wnt pathway. These changes were attenuated by gemigliptin treatment. Gemigliptin restored the decreased expression of vascular smooth muscle cells markers (α-SMA and SM22α) and increased expression of osteogenic makers (CBFA1, OSX, E11, and SOST) induced by phosphate. In conclusion, gemigliptin attenuated vascular calcification and osteogenic trans-differentiation in vascular smooth muscle cells via multiple steps including downregulation of PiT-1 expression and suppression of reactive oxygen species generation, phospho-PI3K/AKT, and the Wnt signaling pathway.

The NADPH oxidase NOX4 represses epithelial to amoeboid transition and efficient tumour dissemination

Epithelial to mesenchymal transition is a common event during tumour dissemination. However, direct epithelial to amoeboid transition has not been characterized to date. Here we provide evidence that cells from hepatocellular carcinoma (HCC), a highly metastatic cancer, undergo epithelial to amoeboid transition in physiological environments, such as organoids or three-dimensional complex matrices. Furthermore, the NADPH oxidase NOX4 inhibits this transition and therefore suppresses efficient amoeboid bleb-based invasion. Moreover, NOX4 expression is associated with E-cadherin levels and inversely correlated with invasive features. NOX4 is necessary to maintain parenchymal structures, increase cell-cell and cell-to-matrix adhesion, and impair actomyosin contractility and amoeboid invasion. Importantly, NOX4 gene deletions are frequent in HCC patients, correlating with higher tumour grade. Contrary to that observed in mesenchymal cell types, here NOX4 suppresses Rho and Cdc42 GTPase expression and downstream actomyosin contractility. In HCC patients, NOX4 expression inversely correlates with RhoC and Cdc42 levels. Moreover, low expression of NOX4 combined with high expression of either RhoC or Cdc42 is associated with worse prognosis. Therefore, loss of NOX4 increases actomyosin levels and favours an epithelial to amoeboid transition contributing to tumour aggressiveness.