Notch1 hyperactivity drives ubiquitination of NOX2 and dysfunction of CD8+ regulatory T cells in patients with systemic lupus erythematosus

OBJECTIVES

Patients with systemic lupus erythematosus (SLE) display heightened immune activation and elevated IgG autoantibody levels, indicating compromised regulatory T cell (Tregs) function. Our recent findings pinpoint CD8+ Tregs as crucial regulators within secondary lymphoid organs, operating in a NOX2-dependent mechanism. However, the specific involvement of CD8+ Tregs in SLE pathogenesis and the mechanisms underlying their role remain uncertain.

METHODS

SLE and healthy individuals were enlisted to assess the quantity and efficacy of Tregs. CD8+CD45RA+CCR7+ Tregs were generated ex vivo, and their suppressive capability was gauged by measuring pZAP70 levels in targeted T cells. Notch1 activity was evaluated by examining activated Notch1 and HES1, with manipulation of Notch1 accomplished with Notch inhibitor DAPT, Notch1 shRNA, and Notch1-ICD. To create humanized SLE chimeras, immune-deficient NSG mice were engrafted with PBMCs from SLE patients.

RESULTS

We observed a reduced frequency and impaired functionality of CD8+ Tregs in SLE patients. There was a downregulation of NOX2 in CD8+ Tregs from SLE patients, leading to a dysfunction. Mechanistically, the reduction of NOX2 in SLE CD8+ Tregs occurred at a post-translational level rather than at the transcriptional level. SLE CD8+ Tregs exhibited heightened Notch1 activity, resulting in increased expression of STUB1, an E3 ubiquitin ligase that binds to NOX2 and facilitates its ubiquitination. Consequently, restoring NOX2 levels and inhibiting Notch1 activity could alleviate the severity of the disease in humanized SLE chimeras.

CONCLUSION

Notch1 is the cell-intrinsic mechanism underlying NOX2 deficiency and CD8+ Treg dysfunction, serving as a therapeutic target for clinical management of SLE.

The NADPH oxidase 2 subunit p47phox binds to the WAVE regulatory complex and p22phox in a mutually exclusive manner

The actin cytoskeleton and reactive oxygen species (ROS) both play crucial roles in various cellular processes. Previous research indicated a direct interaction between two key components of these systems: the WAVE1 subunit of the WAVE regulatory complex (WRC), which promotes actin polymerization and the p47phox subunit of the NADPH oxidase 2 complex (NOX2), which produces ROS. Here, using carefully characterized recombinant proteins, we find that activated p47phox uses its dual Src homology 3 domains to bind to multiple regions within the WAVE1 and Abi2 subunits of the WRC, without altering WRC's activity in promoting Arp2/3-mediated actin polymerization. Notably, contrary to previous findings, p47phox uses the same binding pocket to interact with both the WRC and the p22phox subunit of NOX2, albeit in a mutually exclusive manner. This observation suggests that when activated, p47phox may separately participate in two distinct processes: assembling into NOX2 to promote ROS production and engaging with WRC to regulate the actin cytoskeleton.

Reactive oxygen species and its role in pathogenesis and resistance to therapy in acute myeloid leukemia

Relapse following a short clinical response to therapy is the major challenge for the management of acute myeloid leukemia (AML) patients. Leukemic stem cells (LSC), as the source of relapse, have been investigated for their metabolic preferences and their alterations at the time of relapse. As LSC rely on oxidative phosphorylation (OXPHOS) for energy requirement, reactive oxygen species (ROS), as by-products of OXPHOS, have been investigated for their role in the effectiveness of the standard AML therapy. Increased levels of non-mitochondrial ROS, generated by nicotinamide adenine dinucleotide phosphate oxidase, in a subgroup of AML patients add to the complexity of studying ROS. Although there are various studies presenting the contribution of ROS to AML pathogenesis, resistance, and its inhibition or activation as a target, a model that can clearly explain its role in AML has not been conceptualized. This is due to the heterogeneity of AML, the dynamics of ROS production, which is influenced by factors such as the type of treatment, cell differentiation state, mitochondrial activity, and also the heterogeneous generation of non-mitochondrial ROS and limited available data on their interaction with the microenvironment. This review summarizes these challenges and the recent progress in this field.

Gestational Hypoxia Impaired Endothelial Nitric Oxide Synthesis Via miR-155-5p/NADPH Oxidase/Reactive Oxygen Species Axis in Male Offspring Vessels

BACKGROUND

Nitric oxide (NO) is the most important vasodilator secreted by vascular endothelial cells, and its abnormal synthesis is involved in the development of cardiovascular disease. The prenatal period is a critical time for development and largely determines lifelong vascular health in offspring. Given the high incidence and severity of gestational hypoxia in mid-late pregnancy, it is urgent to further explore whether it affects the long-term synthesis of NO in offspring vascular endothelial cells.

METHODS AND RESULTS

Pregnant Sprague-Dawley rats were housed in a normoxic or hypoxic (10.5% O2) chamber from gestation days 10 to 20. The thoracic aortas of fetal and adult male offspring were isolated for experiments. Gestational hypoxia significantly reduces the NO-dependent vasodilation mediated by acetylcholine in both the fetal and adult offspring thoracic aorta rings. Meanwhile, acetylcholine-induced NO synthesis is impaired in vascular endothelial cells from hypoxic offspring thoracic aortas. We demonstrate that gestational hypoxic offspring exhibit a reduced endothelial NO synthesis capacity, primarily due to increased expression of NADPH oxidase 2 and enhanced reactive oxygen species. Additionally, gestational hypoxic offspring show elevated levels of miR-155-5p in vascular endothelial cells, which is associated with increased expression of NADPH oxidase 2 and reactive oxygen species generation, as well as impaired NO synthesis.

CONCLUSIONS

The present study is the first to demonstrate that gestational hypoxia impairs endothelial NO synthesis via the miR-155-5p/NADPH oxidase 2/reactive oxygen species axis in offspring vessels. These novel findings indicate that the detrimental effects of gestational hypoxia on fetal vascular function can persist into adulthood, providing new insights into the development of vascular diseases.

Inhibition of NOX2 or NLRP3 inflammasome prevents cardiac remote ischemic preconditioning

Introduction: Short episodes of ischemia-reperfusion (IR) in the heart (classical ischemic preconditioning, IPC) or in a limb (remote ischemic preconditioning, RIPC) before a prolonged ischemic episode, reduce the size of the infarct. It is unknown whether IPC and RIPC share common mechanisms of protection. Animals KO for NOX2, a superoxide-producing enzyme, or KO for NLRP3, a protein component of inflammasome, are not protected by IPC. The aim of this study was to investigate if NOX2 or NLRP3 inflammasome are involved in the protection induced by RIPC. Methods: We preconditioned rats using 4 × 5 min periods of IR in the limb with or without a NOX2 inhibitor (apocynin) or an NLRP3 inhibitor (Bay117082). In isolated hearts, we measured the infarct size after 30 min of ischemia and 60 min of reperfusion. In hearts from preconditioned rats we measured the activity of NOX2; the mRNA of Nrf2, gamma-glutamylcysteine ligase, glutathione dehydrogenase, thioredoxin reductase and sulfiredoxin by RT-qPCR; the content of glutathione; the activation of the NLRP3 inflammasome and the content of IL-1β and IL-10 in cardiac tissue. In exosomes isolated from plasma, we quantified NOX2 activity. Results: The infarct size after IR decreased from 40% in controls to 9% of the heart volume after RIPC. This protective effect was lost in the presence of both inhibitors. RIPC increased NOX2 activity in the heart and exosomes, as indicated by the increased association of p47phox to the membrane and by the increased oxidation rate of NADPH. RIPC also increased the mRNA of Nrf2 and antioxidant enzymes. Also, RIPC increased the content of glutathione and the GSH/GSSG ratio. The inflammasome proteins NLRP3, procaspase-1, and caspase-1 were all increased in the hearts of RIPC rats. At the end of RIPC protocol, IL-1β increased in plasma but decreased in cardiac tissue. At the same time, IL-10 did not change in cardiac tissue but increased by 70% during the next 50 min of perfusion. Conclusion: RIPC activates NOX2 which upregulates the heart's antioxidant defenses and activates the NLRP3 inflammasome which stimulates a cardiac anti-inflammatory response. These changes may underlie the decrease in the infarct size induced by RIPC.

Tocovid Attenuated Oxidative Stress and Cognitive Decline by Inhibiting Amyloid-β-Induced NOX2 Activation in Alzheimer's Disease Mice

Background

NADPH oxidase 2 (NOX2) is an important source of reactive oxygen species (ROS). Activated NOX2 may contribute to Alzheimer's disease (AD). Our previous studies showed that a novel vitamin E mixture, Tocovid, had potential neuroprotective effects in a stroke mice model and an AD cell model.

Objective

The aim of this study was two-fold: to assess whether long-term Tocovid treatment can regulate NOX2, and the therapeutic effects of long-term administration of Tocovid to an AD mice model.

Methods

Therapeutic effects of long-term administration of Tocovid (200 mg/kg /day) on an Aβ-overexpressed transgenic AD mice model (APP23, n = 8) was investigated. The therapeutic effect of Tocovid in 16-month-old mice compared with the no-treatment APP23 group (n = 9) was assessed.

Results

Tocovid treatment strongly improved motor and memory deficits of APP23 mice by attenuating NOX2 expression, oxidative stress, neuroinflammation, neurovascular unit dysfunction, synaptic alteration, and Aβ deposition after 16 months.

Conclusion

These findings suggest that NOX2 is a potential target in AD pathology. Long-term administration of Tocovid may be a promising candidate for AD treatment.

Dose-response effect of L-citrulline on skeletal muscle damage after acute eccentric exercise: an in vivo study in mice

Background

Eccentric exercise may trigger mechanical stress, resulting in muscle damage that may decrease athletic performance. L-citrulline potentially prevents skeletal muscle damage after acute eccentric exercise. This study aimed to assess the dose-response effect of L-citrulline as a preventive therapy for skeletal muscle damage in mice after acute eccentric exercise.

Methods

This is a controlled laboratory in vivo study with a post-test-only design. Male mice (BALB/c, n = 25) were randomized into the following groups: a normal control (C1) (n = 5); a negative control (C2) with downhill running and placebo intervention (n = 5); treatment groups: T1 (n = 5), T2 (n = 5), and T3 (n = 5), were subjected to downhill running and 250, 500, and 1,000 mg/kg of L-citrulline, respectively, for seven days. Blood plasma was used to determine the levels of TNNI2 and gastrocnemius muscle tissue NOX2, IL-6, and caspase 3 using ELISA. NF-κB and HSP-70 expressions were determined by immunohistochemistry.

Results

Skeletal muscle damage (plasma TNNI2 levels) in mice after eccentric exercise was lower after 250 and 500 mg/kg of L-citrulline. Further, changes in oxidative stress markers, NOX2, were reduced after a 1,000 mg/kg dose. However, a lower level of change has been observed in levels of cellular response markers (NF-κB, HSP-70, IL-6, and caspase 3) after administration of L-citrulline doses of 250, 500, and 1,000 mg/kg.

Conclusion

L-citrulline may prevent skeletal muscle damage in mice after acute eccentric exercise through antioxidant effects as well as inflammatory and apoptotic pathways. In relation to dose-related effects, it was found that L-citrulline doses of 250, 500, and 1,000 mg/kg significantly influenced the expression of NF-κB and HSP-70, as well as the levels of IL-6 and caspase 3. Meanwhile, only doses of 250 and 500 mg/kg had an impact on TNNI2 levels, and the 1,000 mg/kg dose affected NOX2 levels.

NOX2 control over energy metabolism plays a role in acute myeloid leukaemia prognosis and survival

Acute myeloid leukaemia (AML) is a highly heterogeneous disease, however the therapeutic approaches have hardly changed in the last decades. Metabolism rewiring and the enhanced production of reactive oxygen species (ROS) are hallmarks of cancer. A deeper understanding of these features could be instrumental for the development of specific AML-subtypes treatments. NADPH oxidases (NOX), the only cellular system specialised in ROS production, are also involved in leukemic metabolism control. NOX2 shows a variable expression in AML patients, so patients can be classified based on such difference. Here we have analysed whether NOX2 levels are important for AML metabolism control. The lack of NOX2 in AML cells slowdowns basal glycolysis and oxidative phosphorylation (OXPHOS), along with the accumulation of metabolites that feed such routes, and a sharp decrease of glutathione. In addition, we found changes in the expression of 725 genes. Among them, we have discovered a panel of 30 differentially expressed metabolic genes, whose relevance was validated in patients. This panel can segregate AML patients according to CYBB expression, and it can predict patient prognosis and survival. In summary, our data strongly support the relevance of NOX2 for AML metabolism, and highlights the potential of our discoveries in AML prognosis.

Protective effects of tanshinone IIA on Porphyromonas gingivalis-induced atherosclerosis via the downregulation of the NOX2/NOX4-ROS mediation of NF-κB signaling pathway

Tanshinone IIA (TSA), an active component isolated from Danshen, possess high medicinal values against atherosclerosis by reducing vascular oxidative stress, inhibiting platelet aggregation, and protecting the endothelium from damage. The periodontal pathogen Porphyromonas gingivalis (P. gingivalis) has been proven to accelerate the development of atherosclerosis. We aim to determine the effects of TSA on P. gingivalis-induced atherosclerosis in ApoE-knockout (ApoE-/-) mice. After feeding with a high-lipid diet and infected with P. gingivalis three times per week for four weeks, TSA-treated (60 mg/kg/d) mice greatly inhibited atherosclerotic lesions both morphologically and biochemically and exhibited significantly reduction ROS, 8-OHdG, and ox-LDL levels in serum compared with P. gingivalis-infected mice. Additionally, TSA-treated mice were observed a marked reduction of ROS, 8-OHdG and ox-LDL in the serum, mRNA levels of COX-2, LOX-1, NOX2 and NOX4 in the aorta, as well as the levels of NOX2, NOX4, and NF-κB. These results suggest that TSA attenuates oxidative stress by decreasing NOX2 and NOX4 and downregulating NF-κB signaling pathway, which might be contributed to the amelioration of atherosclerosis.

TNFα counteracts interleukin-10 anti-inflammatory pathway through the NOX2-Lyn-SHP-1 axis in human monocytes

TNFα-mediated signaling pathways play a pivotal role in the pathogenesis of inflammatory diseases such as rheumatoid arthritis (RA) and inflammatory bowel disease (IBD) by promoting phagocyte inflammatory functions, notably cytokine release and reactive oxygen species (ROS) production by NOX2. In contrast, interleukin-10 (IL-10), a powerful anti-inflammatory cytokine, potently shuts down phagocyte activation, making IL-10 an attractive therapeutic candidate. However, IL-10 therapy has shown limited efficacy in patients with inflammatory diseases. Here, we report that TNFα blocks IL-10 anti-inflammatory pathways in human monocytes, thereby prolonging inflammation. TNFα decreased IL-10-induced phosphorylation of STAT3 and consequently IL-10-induced expression of the major anti-inflammatory factor, SOCS3. Decreased STAT3 phosphorylation was due to a SHP1/2 phosphatase, as NSC-87877, a SHP1/2 inhibitor, restored STAT3 phosphorylation and prevented the TNFα-induced inhibition of IL-10 signaling. TNFα activated only SHP1 in human monocytes and this activation was NOX2-dependent, as diphenyleneiodonium, a NOX2 inhibitor, suppressed SHP1 activation and STAT3 dephosphorylation triggered by TNFα. ROS-induced activation of SHP1 was mediated by the redox-sensitive kinase, Lyn, as its inhibition impeded TNFα-induced SHP1 activation and STAT3 dephosphorylation. Furthermore, H2O2 recapitulated TNFα-inhibitory activity on IL-10 signaling. Finally, NSC-87877 dampened collagen antibody-induced arthritis (CAIA) in mice. These results reveal that TNFα disrupts IL-10 signaling by inducing STAT3 dephosphorylation through a NOX2-ROS-Lyn-SHP1 axis in human monocytes and that inhibition of SHP1/2 in vivo protects against CAIA. These new findings might explain the poor efficacy of IL-10 therapy in patients with inflammatory diseases and suggest that anti-TNFα agents and SHP1/2 inhibitors could improve the therapeutic use of IL-10.

Traumatic brain injury-induced inflammatory changes in the olfactory bulb disrupt neuronal networks leading to olfactory dysfunction

Approximately 20-68% of traumatic brain injury (TBI) patients exhibit trauma-associated olfactory deficits (OD) which can compromise not only the quality of life but also cognitive and neuropsychiatric functions. However, few studies to date have examined the impact of experimental TBI on OD. The present study examined inflammation and neuronal dysfunction in the olfactory bulb (OB) and the underlying mechanisms associated with OD in male mice using a controlled cortical impact (CCI) model. TBI caused a rapid inflammatory response in the OB as early as 24 h post-injury, including elevated mRNA levels of proinflammatory cytokines, increased numbers of microglia and infiltrating myeloid cells, and increased IL1β and IL6 production in these cells. These changes were sustained for up to 90 days after TBI. Moreover, we observed significant upregulation of the voltage-gated proton channel Hv1 and NOX2 expression levels, which were predominantly localized in microglia/macrophages and accompanied by increased reactive oxygen species production. In vivo OB neuronal firing activities showed early neuronal hyperexcitation and later hypo-neuronal activity in both glomerular layer and mitral cell layer after TBI, which were improved in the absence of Hv1. In a battery of olfactory behavioral tests, WT/TBI mice displayed significant OD. In contrast, neither Hv1 KO/TBI nor NOX2 KO/TBI mice showed robust OD. Finally, seven days of intranasal delivery of a NOX2 inhibitor (NOX2ds-tat) ameliorated post-traumatic OD. Collectively, these findings highlight the importance of OB neuronal networks and its role in TBI-mediated OD. Thus, targeting Hv1/NOX2 may be a potential intervention for improving post-traumatic anosmia.

Inhibition of NADPH oxidase 2 improves cognitive abilities by modulating aquaporin-4 after traumatic brain injury in mice

Traumatic brain injury (TBI) is caused by acquired damage that includes cerebral edema after a mechanical injury and may cause cognitive impairment. We explored the role of nicotinamide adenine dinucleotide phosphate oxidase 2 (NADPH oxidase 2; NOX2) and aquaporin-4 (AQP4) in the process of edema and cognitive abilities after TBI in NOX2-/- and AQP4-/- mice by using the Morris water maze test (MWM), step-down test (STD), novel object recognition test (NOR) and western blotting. Knockout of NOX2 in mice decreased the AQP4 and reduce edema in the hippocampus and cortex after TBI in mice. Moreover, inhibiting AQP4 by 2-(nicotinamide)-1,3,4-thiadiazole (TGN-020) or genetic deletion of AQP4 could attenuate neurological deficits without changing reactive oxygen species (ROS) levels after TBI in mice. Taken together, we suspected that inhibiting NOX2 could improve cognitive abilities by modulating ROS levels, then affecting AQP4 levels and brain edema after in TBI mice. Our study demonstrated that NOX2 play a key role in decreasing edema in brain and improving cognitive abilities by modulating AQP4 after TBI.

NADPH Oxidases and Oxidative Stress in the Pathogenesis of Atrial Fibrillation

Atrial fibrillation (AF) is the most common type of cardiac arrhythmia and its prevalence increases with age. The irregular and rapid contraction of the atria can lead to ineffective blood pumping, local blood stasis, blood clots, ischemic stroke, and heart failure. NADPH oxidases (NOX) and mitochondria are the main sources of reactive oxygen species in the heart, and dysregulated activation of NOX and mitochondrial dysfunction are associated with AF pathogenesis. NOX- and mitochondria-derived oxidative stress contribute to the onset of paroxysmal AF by inducing electrophysiological changes in atrial myocytes and structural remodeling in the atria. Because high atrial activity causes cardiac myocytes to expend extremely high energy to maintain excitation-contraction coupling during persistent AF, mitochondria, the primary energy source, undergo metabolic stress, affecting their morphology, Ca2+ handling, and ATP generation. In this review, we discuss the role of oxidative stress in activating AF-triggered activities, regulating intracellular Ca2+ handling, and functional and anatomical reentry mechanisms, all of which are associated with AF initiation, perpetuation, and progression. Changes in the extracellular matrix, inflammation, ion channel expression and function, myofibril structure, and mitochondrial function occur during the early transitional stages of AF, opening a window of opportunity to target NOX and mitochondria-derived oxidative stress using isoform-specific NOX inhibitors and mitochondrial ROS scavengers, as well as drugs that improve mitochondrial dynamics and metabolism to treat persistent AF and its transition to permanent AF.

NOX2 deficiency enhances priming and activation of the NLRP3 inflammasome

BACKGROUND

Nicotinamide adenine dinucleotide phosphate oxidase complex 2 (NOX2) deficiency, or chronic granulomatous disease (CGD), is an inborn error of immunity associated with increased susceptibility to infection and inflammatory manifestations. The pathophysiologic mechanism leading to the increased inflammatory response in CGD remains elusive.

OBJECTIVE

We investigated the pathophysiologic mechanisms leading to NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation in NOX2 deficiency.

METHODS

We used NOX2-deficient human primary and CRISPR-engineered macrophages to show that NOX2 deficiency enhances the inflammatory response mainly by modulating the 2 steps of NLRP3 inflammasome activation: its transcriptional priming and its posttranslational triggering.

RESULTS

At the transcriptional level, NOX2-deficient phagocytes display increased priming of the NLRP3 inflammasome, as evidenced by increased transcription of NLRP3 and IL-1β through an IL-1β-dependent stimulation of the nuclear factor kappa-light-chain enhancer of activated B cells (aka NF-κB) pathway. At the posttranslational level, the absence of NOX2 triggers the NLRP3 inflammasome activation by increased K+ efflux and excessive release of mitochondrial DNA due to mitochondrial damage. Furthermore, NLRP3-driven pyroptosis in NOX2-deficient phagocytes further enhances NLRP3 activation by increasing K+ efflux.

CONCLUSION

Our results unveil the role of NOX2 as a repressor of the inflammatory response at both transcriptional and posttranslational levels and pave the way for a more targeted approach to treating CGD patients with inflammatory manifestations.

Activated SIRT1 contributes to DPT-induced glioma cell parthanatos by upregulation of NOX2 and NAT10

Parthanatos is a type of programmed cell death dependent on hyper-activation of poly (ADP-ribose) polymerase 1 (PARP-1). SIRT1 is a highly conserved nuclear deacetylase and often acts as an inhibitor of parthanatos by deacetylation of PARP1. Our previous study showed that deoxypodophyllotoxin (DPT), a natural compound isolated from the traditional herb Anthriscus sylvestris, triggered glioma cell death via parthanatos. In this study, we investigated the role of SIRT1 in DPT-induced human glioma cell parthanatos. We showed that DPT (450 nmol/L) activated both PARP1 and SIRT1, and induced parthanatos in U87 and U251 glioma cells. Activation of SIRT1 with SRT2183 (10 μmol/L) enhanced, while inhibition of SIRT1 with EX527 (200 μmol/L) or knockdown of SIRT1 attenuated DPT-induced PARP1 activation and glioma cell death. We demonstrated that DPT (450 nmol/L) significantly decreased intracellular NAD+ levels in U87 and U251 cells. Further decrease of NAD+ levels with FK866 (100 μmol/L) aggravated, but supplement of NAD+ (0.5, 2 mmol/L) attenuated DPT-induced PARP1 activation. We found that NAD+ depletion enhanced PARP1 activation via two ways: one was aggravating ROS-dependent DNA DSBs by upregulation of NADPH oxidase 2 (NOX2); the other was reinforcing PARP1 acetylation via increase of N-acetyltransferase 10 (NAT10) expression. We found that SIRT1 activity was improved when being phosphorylated by JNK at Ser27, the activated SIRT1 in reverse aggravated JNK activation via upregulating ROS-related ASK1 signaling, thus forming a positive feedback between JNK and SIRT1. Taken together, SIRT1 activated by JNK contributed to DPT-induced human glioma cell parthanatos via initiation of NAD+ depletion-dependent upregulation of NOX2 and NAT10.

Effect of Colchicine in reducing MMP-9, NOX2, and TGF- β1 after myocardial infarction

BACKGROUND

According to WHO 2020, CAD is the second leading cause of death in Indonesia with death cases reaching 259,297 or 15.33% of total deaths. Unfortunately, most of the patients of CAD in Indonesia did not match the golden period or decline to be treated with Percutaneous Coronary Intervention (PCI). Based on the recent study, there were increases in MMP-9, NOX2, and TGF-β1 in STEMI patients which contribute to cardiac remodeling. Moreover, there is controversy regarding the benefit of late PCI (12-48 hours after onset of STEMI) in stable patients. Lately, colchicine is widely used in cardiovascular disease. This study was conducted to explore the effect of colchicine to reduce MMP- 9, NOX2, and TGF-β1 levels after myocardial infarction in stable patients.

METHOD

In this clinical trial study, we assessed 129 STEMI patients, about 102 patients who met inclusion criteria were randomized into four groups. Around 25 patients received late PCI (12-48 h after the onset of chest pain), optimal medical treatment (OMT) for STEMI, and colchicine; 24 patients received late PCI and OMT; 22 patients didn't get the revascularization (No Revas), OMT, and colchicine; and 31 patients received No Revas and OMT only. The laboratory test for MMP-9, NOX2, and TGF-β1 were tested in Day-1 and Day-5. The data were analyzed using Mann-Whitney.

RESULTS

A total of 102 patients with mean age of 56 ± 9.9, were assigned into four groups. The data analysis showed significant results within No Revas + OMT + Colchicine group versus No Revas + OMT + Placebo in MMP-9 (Day-1: p = 0.001; Day-5: p = 0.022), NOX2 (Day-1: p = 0.02; Day-5: p = 0.026), and TGF-β1 (Day-1: p = 0.00; Day-5: p = 0.00) with the less three markers in OMT + Colchicine group than OMT + Placebo group. There were no significant differences within the late PCI + OMT + colchicine group and PCI + OMT + Placebo group.

CONCLUSIONS

Colchicine could significantly reduce MMP-9, NOX2, and TGF-β1 levels in stable STEMI patients. So that, colchicine could be a potential agent in STEMI patients and prevent cardiac remodeling events.

Apocynin, an NADPH Oxidase Enzyme Inhibitor, Prevents Amebic Liver Abscess in Hamster

Amebiasis is an intestinal infection caused by Entamoeba histolytica. Amebic liver abscess (ALA) is the most common extraintestinal complication of amebiasis. In animal models of ALA, neutrophils have been shown to be the first cells to come into contact with Entamoeba histolytica during the initial phase of ALA. One of the multiple mechanisms by which neutrophils exhibit amebicidal activity is through reactive oxygen species (ROS) and the enzyme NADPH oxidase (NOX2), which generates and transports electrons to subsequently reduce molecular oxygen into superoxide anion. Previous reports have shown that ROS release in the susceptible animal species (hamster) is mainly stimulated by the pathogen, in turn provoking such an exacerbated inflammatory reaction that it is unable to be controlled and results in the death of the animal model. Apocynin is a natural inhibitor of NADPH oxidase. No information is available on the role of NOX in the evolution of ALA in the hamster, a susceptible model. Our study showed that administration of a selective NADPH oxidase 2 (NOX2) enzyme inhibitor significantly decreases the percentage of ALA, the size of inflammatory foci, the number of neutrophils, and NOX activity indicated by the reduction in superoxide anion (O2-) production. Moreover, in vitro, the apocynin damages amoebae. Our results showed that apocynin administration induces a decrease in the activity of NOX that could favor a decrease in ALA progression.

Purinergic receptor P2X7 activates NOX2/JNK signaling to participate in granulosa cell inflammation and apoptosis in polycystic ovary syndrome

Increasing evidence shows that polycystic ovary syndrome (PCOS) is often accompanied by an inflammatory response, hence, appropriately managing granulosa cell inflammation is critical to regaining ovarian function in PCOS. In this study, the differential levels of purinergic receptor P2X7 between the control and PCOS samples in the dataset GSE34526 were assessed, then PCOS mouse models were established. Following evaluating the fluctuations in hormone levels, inflammatory cytokines, and P2X7, mice received treatment with the P2X7 antagonist A740003. Its effects on hormones, inflammation, apoptosis, and NOX2 signaling in mice were examined. Afterward, primary mouse granulosa cells were isolated, and the mediating role of NOX2 signaling in the P2X7 regulatory pathway was confirmed by transfection of NOX2 overexpression plasmids. The results demonstrated that P2X7 was significantly elevated in the PCOS samples in the dataset. Compared with the control group, PCOS mice had significant differences in the follicle-stimulating hormone, luteinizing hormone, testosterone, anti-Müllerian hormone, inflammatory factors, and P2X7. Treatment with A740003 partially restored these parameter levels, including NOX2 signaling. Based on in vitro experiments on primary mouse granulosa cells, the above findings were re-verified, and the overexpression of NOX2 could reverse the regulatory function of P2X7. The present study highlights that P2X7 level increases in PCOS, and inhibition of P2X7 can reduce disease symptoms. It is involved in inflammation and apoptosis in granulosa cells through NOX2/JNK signaling.

Unlocking the power of NOX2: A comprehensive review on its role in immune regulation

Reactive oxygen species (ROS) are a family of highly reactive molecules with numerous, often pleiotropic functions within the cell and the organism. Due to their potential to destroy biological structures such as membranes, enzymes and organelles, ROS have long been recognized as harmful yet unavoidable by-products of cellular metabolism leading to "oxidative stress" unless counterbalanced by cellular anti-oxidative defense mechanisms. Phagocytes utilize this destructive potential of ROS released in high amounts to defend against invading pathogens. In contrast, a regulated and fine-tuned release of "signaling ROS" (sROS) provides essential intracellular second messengers to modulate central aspects of immunity, including antigen presentation, activation of antigen presenting cells (APC) as well as the APC:T cell interaction during T cell activation. This regulated release of sROS is foremost attributed to the specialized enzyme NADPH-oxidase (NOX) 2 expressed mainly in myeloid cells such as neutrophils, macrophages and dendritic cells (DC). NOX-2-derived sROS are primarily involved in immune regulation and mediate protection against autoimmunity as well as maintenance of self-tolerance. Consequently, deficiencies in NOX2 not only result in primary immune-deficiencies such as Chronic Granulomatous Disease (CGD) but also lead to auto-inflammatory diseases and autoimmunity. A comprehensive understanding of NOX2 activation and regulation will be key for successful pharmaceutical interventions of such ROS-related diseases in the future. In this review, we summarize recent progress regarding immune regulation by NOX2-derived ROS and the consequences of its deregulation on the development of immune disorders.

NOX2 inhibition stabilizes vulnerable plaques by enhancing macrophage efferocytosis via MertK/PI3K/AKT pathway

NADPH oxidases 2 (NOX2) is the main source of ROS in macrophages, which plays a critical role in the formation of atherosclerosis. However, effects of NOX2 inhibition on established vulnerable plaques and the potential role involved remain unclear. The purpose of this study is to investigate the latent mechanism of NOX2-triggered vulnerable plaque development. We generated a vulnerable carotid plaque model induced by carotid branch ligation and renal artery constriction, combined with a high-fat diet in ApoE^-/- mice. NOX2 specific inhibitor, GSK2795039 (10 mg/kg/day by intragastric administration for 8 weeks) significantly prevented vulnerable plaque, evaluated by micro-ultrasound imaging parameters. A profile of less intraplaque hemorrhage detection, increased collagen-lipid ratio, fibrous cap thickness and less necrotic core formation were also found in GSK2795039 treated group. Mechanistically, reduced 4-HNE, in situ lesional apoptosis and enhanced efferocytosis were involved in mice treated with NOX2 inhibitor. Further analysis in mouse macrophages confirmed the role of NOX2 inhibition in enhancing macrophage efferocytosis by regulating the MertK/PI3K/AKT pathway. In summary, our data defined previously few recognized roles of NOX2 in vulnerable plaque pathogenesis and an undescribed NOX2-ROS-MerTK axis acts involved in regulating macrophage efferocytosis in the formation of rupture-prone vulnerable plaques.

Astragaloside IV targets PRDX6, inhibits the activation of RAC subunit in NADPH oxidase 2 for oxidative damage

BACKGROUND

Radix Astragali Mongolici, as a traditional Chinese medicine, is widely used in the treatment of qi deficiency, viral or bacterial infection, inflammation and cancer. Astragaloside IV (AST), a key active compound in Radix Astragali Mongolici, has been shown to reduce disease progression by inhibiting oxidative stress and inflammation. However, the specific target and mechanism of action of AST in improving oxidative stress are still unclear.

PURPOSE

This study aims to explore the target and mechanism of AST to improve oxidative stress, and to explain the biological process of oxidative stress.

METHODS

AST functional probes were designed to capture target proteins and combined with protein spectrum to analyze target proteins. Small molecule and protein interaction technologies were used to verify the mode of action, while computer dynamics simulation technology was used to analyze the site of interaction with the target protein. The pharmacological activity of AST in improving oxidative stress was evaluated in a mouse model of acute lung injury induced by LPS. Additionally, pharmacological and serial molecular biological approaches were used to explore the underlying mechanism of action.

RESULTS

AST inhibits PLA2 activity in PRDX6 by targeting the PLA2 catalytic triad pocket. This binding alters the conformation and structural stability of PRDX6 and interferes with the interaction between PRDX6 and RAC, hindering the activation of the RAC-GDI heterodimer. Inactivation of RAC prevents NOX2 maturation, attenuates superoxide anion production, and improves oxidative stress damage.

CONCLUSION

The findings of this research indicate that AST impedes PLA2 activity by acting on the catalytic triad of PRDX6. This, in turn, disrupts the interaction between PRDX6 and RAC, thereby hindering the maturation of NOX2 and diminishing the oxidative stress damage.

Metformin inhibits ovarian granular cell pyroptosis through the miR-670-3p/NOX2/ROS pathway

Recent studies have demonstrated that ovarian granular cells (OGCs) pyroptosis is present in the ovaries of polycystic ovary syndrome (PCOS) mice and that NLRP3 activation destroys follicular functions. Metformin has been shown to protect against PCOS by reducing insulin resistance in women, whereas its role in OGC pyroptosis is unknown. This study aimed to investigate the impact of metformin on OGC pyroptosis and the underlying mechanisms. The results showed that treating a human granulosa-like tumor cell line (KGN) with metformin significantly decreased LPS-induced expression of miR-670-3p, NOX2, NLRP3, ASC, cleaved caspase-1, and GSDMD-N. Cellular caspase-1 activity; ROS production; oxidative stress; and the secretion of IL-1β, IL-6, IL-18, and TNF-α were also diminished. These effects were amplified by adding N-acetyl-L-cysteine (NAC), a pharmacological inhibitor of ROS. In contrast, metformin's anti-pyroptosis and anti-inflammatory effects were robustly ameliorated by NOX2 overexpression in KGN cells. Moreover, bioinformatic analyses, RT-PCR, and Western blotting showed that miR-670-3p could directly bind to the NOX2 (encoded by the CYBB gene in humans) 3'UTR and decrease NOX2 expression. Metformin-induced suppression of NOX2 expression, ROS production, oxidative stress, and pyroptosis was significantly alleviated by transfection with the miR-670-3p inhibitor. These findings suggest that metformin inhibits KGN cell pyroptosis via the miR-670-3p/NOX2/ROS pathway.

Inhibition of NADPH Oxidase (NOX) 2 Mitigates Colitis in Mice with Impaired Macrophage AMPK Function

Macrophage adenosine monophosphate-activated protein kinase (AMPK) limits the development of experimental colitis. AMPK activation inhibits NADPH oxidase (NOX) 2 expression, reactive oxygen species (ROS) generation, and pro-inflammatory cytokine secretion in macrophages during inflammation, while increased NOX2 expression is reported in experimental models of colitis and inflammatory bowel disease (IBD) patients. Although there are reductions in AMPK activity in IBD, it remains unclear whether targeted inhibition of NOX2 in the presence of defective AMPK can reduce the severity of colitis. Here, we investigate whether the inhibition of NOX2 ameliorates colitis in mice independent of AMPK activation. Our study identified that VAS2870 (a pan-Nox inhibitor) alleviated dextran sodium sulfate (DSS)-induced colitis in macrophage-specific AMPKβ1-deficient (AMPKβ1^LysM) mice. Additionally, VAS2870 blocked LPS-induced TLR-4 and NOX2 expression, ROS production, nuclear translocation of NF-κB, and pro-inflammatory cytokine secretion in bone marrow-derived macrophages (BMDMs) from AMPKβ1^LysM mice, whereas sodium salicylate (SS; AMPK β1 activator) did not. Both VAS2870 and SS inhibited LPS-induced NOX2 expression, ROS production, and pro-inflammatory cytokine secretions in bone marrow-derived macrophages (BMDMs) from wildtype (AMPKβ1^fl/fl) mice but only VAS2870 inhibited these effects of LPSs in AMPKβ1^LysM BMDMs. Furthermore, in macrophage cells (RAW 264.7), both SS and VAS2870 inhibited ROS production and the secretion of pro-inflammatory cytokines and reversed the impaired autophagy induced by LPSs. These data suggest that inhibiting NOX2 can reduce inflammation independent of AMPK in colitis.

CRISPR-gene-engineered CYBB knock-out PLB-985 cells, a useful model to study functional impact of X-linked chronic granulomatous disease mutations: application to the G412E X91+-CGD mutation

Chronic granulomatous disease (CGD) is a rare primary immune disorder caused by mutations in one of the five subunits of the NADPH oxidase complex expressed in phagocytes. Two-thirds of CGD cases are caused by mutations in CYBB that encodes NOX2 or gp91phox. Some rare X91+-CGD point mutations lead to a loss of function but with a normal expression of the mutated NOX2 protein. It is therefore necessary to ensure that this mutation is indeed responsible for the loss of activity in order to make a safe diagnosis for genetic counselling. We previously used the X-CGD PLB-985 cell model of M.C. Dinauer obtained by homologous recombination in the original PLB-985 human myeloid cell line, in order to study the functional impact of such mutations. Although the PLB-985 cell line was originally described by K.A. Tucker et al. in1987 as a distinct cell line isolated from a patient with acute nonlymphocytic leukemia, it is actually identified as a subclone of the HL-60 cells. In order to use a cellular model that meets the quality standard for the functional study of X91+-CGD mutations in CGD diagnosis, we developed our own model using the CRISPR-Cas9 technology in a certified PLB-985 cell line from DSMZ-German Collection of Microorganisms and Cell Cultures. Thanks to this new X-CGD model, we demonstrated that the G412E mutation in NOX2 found in a X91+-CGD patient prohibits access of the electron donor NADPH to its binding site explaining the absence of superoxide production in his neutrophils.

Activation of neuronal NADPH oxidase NOX2 promotes inflammatory neurodegeneration

Strong evidence indicates critical roles of NADPH oxidase (a key superoxide-producing enzyme complex during inflammation) in activated microglia for mediating neuroinflammation and neurodegeneration. However, little is known about roles of neuronal NADPH oxidase in neurodegenerative diseases. This study aimed to investigate expression patterns, regulatory mechanisms and pathological roles of neuronal NADPH oxidase in inflammation-associated neurodegeneration. The results showed persistent upregulation of NOX2 (gp91^phox; the catalytic subunit of NADPH oxidase) in both microglia and neurons in a chronic mouse model of Parkinson's disease (PD) with intraperitoneal LPS injection and LPS-treated midbrain neuron-glia cultures (a cellular model of PD). Notably, NOX2 was found for the first time to exhibit a progressive and persistent upregulation in neurons during chronic neuroinflammation. While primary neurons and N27 neuronal cells displayed basal expression of NOX1, NOX2 and NOX4, significant upregulation only occurred in NOX2 but not NOX1 or NOX4 under inflammatory conditions. Persistent NOX2 upregulation was associated with functional outcomes of oxidative stress including increased ROS production and lipid peroxidation. Neuronal NOX2 activation displayed membrane translocation of cytosolic p47^phox subunit and was inhibited by apocynin and diphenyleneiodonium chloride (two widely-used NADPH oxidase inhibitors). Importantly, neuronal ROS production, mitochondrial dysfunction and degeneration induced by inflammatory mediators in microglia-derived conditional medium were blocked by pharmacological inhibition of neuronal NOX2. Furthermore, specific deletion of neuronal NOX2 prevented LPS-elicited dopaminergic neurodegeneration in neuron-microglia co-cultures separately grown in the transwell system. The attenuation of inflammation-elicited upregulation of NOX2 in neuron-enriched and neuron-glia cultures by ROS scavenger N-acetylcysteine indicated a positive feedback mechanism between excessive ROS production and NOX2 upregulation. Collectively, our findings uncovered crucial contribution of neuronal NOX2 upregulation and activation to chronic neuroinflammation and inflammation-related neurodegeneration. This study reinforced the importance of developing NADPH oxidase-targeting therapeutics for neurodegenerative diseases.

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.

Caspase Inhibition Modulates Monocyte-Derived Macrophage Polarization in Damaged Tissues

Circulating monocytes are recruited in damaged tissues to generate macrophages that modulate disease progression. Colony-stimulating factor-1 (CSF-1) promotes the generation of monocyte-derived macrophages, which involves caspase activation. Here, we demonstrate that activated caspase-3 and caspase-7 are located to the vicinity of the mitochondria in CSF1-treated human monocytes. Active caspase-7 cleaves p47^PHOX at aspartate 34, which promotes the formation of the NADPH (nicotinamide adenine dinucleotide phosphate) oxidase complex NOX2 and the production of cytosolic superoxide anions. Monocyte response to CSF-1 is altered in patients with a chronic granulomatous disease, which are constitutively defective in NOX2. Both caspase-7 down-regulation and radical oxygen species scavenging decrease the migration of CSF-1-induced macrophages. Inhibition or deletion of caspases prevents the development of lung fibrosis in mice exposed to bleomycin. Altogether, a non-conventional pathway that involves caspases and activates NOX2 is involved in CSF1-driven monocyte differentiation and could be therapeutically targeted to modulate macrophage polarization in damaged tissues.

Structure, Activation, and Regulation of NOX2: At the Crossroad between the Innate Immunity and Oxidative Stress-Mediated Pathologies

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) is a multisubunit enzyme complex that participates in the generation of superoxide or hydrogen peroxide (H₂O₂) and plays a key role in several biological functions. Among seven known NOX isoforms, NOX2 was the first identified in phagocytes but is also expressed in several other cell types including endothelial cells, platelets, microglia, neurons, and muscle cells. NOX2 has been assigned multiple roles in regulating many aspects of innate and adaptive immunity, and human and mouse models of NOX2 genetic deletion highlighted this key role. On the other side, NOX2 hyperactivation is involved in the pathogenesis of several diseases with different etiologies but all are characterized by an increase in oxidative stress and inflammatory process. From this point of view, the modulation of NOX2 represents an important therapeutic strategy aimed at reducing the damage associated with its hyperactivation. Although pharmacological strategies to selectively modulate NOX2 are implemented thanks to new biotechnologies, this field of research remains to be explored. Therefore, in this review, we analyzed the role of NOX2 at the crossroads between immunity and pathologies mediated by its hyperactivation. We described (1) the mechanisms of activation and regulation, (2) human, mouse, and cellular models studied to understand the role of NOX2 as an enzyme of innate immunity, (3) some of the pathologies associated with its hyperactivation, and (4) the inhibitory strategies, with reference to the most recent discoveries.

NOX2 inhibition enables retention of the circadian clock in BV2 microglia and primary macrophages

Introduction

Sustained neuroinflammation is a major contributor to the progression of neurodegenerative diseases such as Alzheimer's (AD) and Parkinson's (PD) diseases. Neuroinflammation, like other cellular processes, is affected by the circadian clock. Microglia, the resident immune cells in the brain, act as major contributors to neuroinflammation and are under the influence of the circadian clock. Microglial responses such as activation, recruitment, and cytokine expression are rhythmic in their response to various stimuli. While the link between circadian rhythms and neuroinflammation is clear, significant gaps remain in our understanding of this complex relationship. To gain a greater understanding of this relationship, the interaction between the microglial circadian clock and the enzyme NADPH Oxidase Isoform 2 (NOX2) was studied; NOX2 is essential for the production of reactive oxygen species (ROS) in oxidative stress, an integral characteristic of neuroinflammation.

Methods

BV2 microglia were examined over circadian time, demonstrating oscillations of the clock genes Per2 and Bmal1 and the NOX2 subunits gp91phox and p47phox.

Results

The BV2 microglial clock exerted significant control over NOX2 expression and inhibition of NOX2 enabled the microglia to retain a functional circadian clock while reducing levels of ROS and inflammatory cytokines. These trends were mirrored in mouse bone marrow-derived primary macrophages.

Conclusions

NOX2 plays a crucial role in the interaction between the circadian clock and the activation of microglia/macrophages into their pro-inflammatory state, which has important implications in the control of neuroinflammation.

Exosomal RBP4 potentiated hepatic lipid accumulation and inflammation in high-fat-diet-fed mice by promoting M1 polarization of Kupffer cells

Exosomes containing various biological cargoes have potential to be novel diagnostic biomarkers for metabolic diseases. In this study, retinol-binding protein 4 (RBP4) was found to be enriched in serum exosomes, and its increased levels could be considered as an independent risk factor for the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Exosomal RBP4 (exo-RBP4), primarily derived from hepatocytes, significantly enhanced the M1-like polarization of Kupffer cells (KCs) via promoting the activation of NOX2 and NF-κB and reactive oxygen species (ROS) accumulation, resulting in the over-production of inflammatory cytokines including TNF-α. Subsequently, those excess cytokines remarkably increased the levels of intracellular free fatty acid uptake and lipogenesis-related genes (FAS and SREBP-1c) but decreased fatty acid degradation-related genes (CPT-1 and PPARα) in palmitic acid-treated LO2 cells. More notably, TNF-α significantly elevated RBP4 transcription by activating STAT3 in hepatocytes, playing a positive role in NAFLD development. Intravenous injection with RBP4 (50 μg/kg) potentiated hepatic lipid accumulation, M1-type KC proportion, and serum pro-inflammatory cytokine levels in the hepatic tissues of high-fat-diet-fed mice. Collectively, these data indicated that exo-RBP4 converted KCs to M1 subtype by mediating the NOX2/ROS/NF-κB pathway, subsequently promoting de novo lipogenesis in hepatocytes by TNF-α secretion to activate the JAK2/STAT3 signaling pathway. Therefore, this study uncovered a novel intercellular communication between the inflammatory microenvironment and lipid metabolism for fostering NAFLD progression and found the potential of exo-RBP4 as a novel diagnostic biomarker and therapeutic target for NAFLD.

Effects of NADPH Oxidase Isoform-2 (NOX2) Inhibition on Behavioral Responses and Neuroinflammation in a Mouse Model of Neuropathic Pain

NADPH oxidase isoform-2 (NOX2) has been implicated in the pathophysiology of neuropathic pain (NP), mostly through the modulation of neuroinflammation. Since it is also accepted that some neuroimmune mechanisms underlying NP are sex-dependent, we aimed to evaluate the effects of early systemic treatment with the NOX2-selective inhibitor (NOX2i) GSK2795039 on behavioral responses and spinal neuroinflammation in spared nerve injury (SNI)-induced NP in male and female mice. Mechanical sensitivity was evaluated with the von Frey test, while general well-being and anxiety-like behavior were assessed with burrowing and light/dark box tests. Spinal microglial activation and cytokines IL-1β, IL-6, and IL-10, as well as macrophage colony-stimulating factor (M-CSF) were evaluated by immunofluorescence and multiplex immunoassay, respectively. NOX2i treatment reduced SNI-induced mechanical hypersensitivity and early SNI-induced microglial activation in both sexes. SNI-females, but not males, showed a transient reduction in burrowing activity. NOX2i treatment did not improve their burrowing activity, but tendentially reduced their anxiety-like behavior. NOX2i marginally decreased IL-6 in females, and increased M-CSF in males. Our findings suggest that NOX2-selective inhibition may be a potential therapeutic strategy for NP in both male and female individuals, with particular interest in females due to its apparent favorable impact in anxiety-like behavior.

Renoprotective Effect of Thymoquinone against Streptozotocin-Induced Diabetic Nephropathy: Role of NOX2 and Nrf2 Signals

OBJECTIVE

Diabetic nephropathy is an unavoidable complication of chronic uncontrolled diabetes mellitus. The pathogenesis of diabetic nephropathy is multifactorial, and the development of an effective therapy remains to be elucidated. The aim of the present study was to assess the role of NOX2 and Nrf2 in the protective mechanism of thymoquinone (THQ) against streptozotocin (STZ)-induced diabetic nephropathy.

METHODS

Rats were injected with STZ (55 mg/kg) to induce diabetes. The diabetic rats were orally treated with THQ (10 mg/kg/day) for eight weeks.

RESULTS

STZ-treated rats exhibit an elevation of serum creatinine, serum urea, and creatinine clearance. The renal abnormalities were associated with increased NADPH oxidase isoform, NOX2 protein expression, and activity, along with elevated malondialdehyde (MDA). In addition, the tumor necrotic factor-alpha (TNF-α) level and nitric oxide (NO) bioavailability, as well as the transforming growth factor-beta (TGF)-β, were markedly increased. On the other hand, the nuclear factor-E2-related factor (Nrf2) protein expression was significantly reduced in diabetic rats compared to the control. However, treatment with THQ significantly reversed these alterations with subsequent ameliorating renal dysfunction and pathological abnormalities.

CONCLUSION

The present study demonstrates that THQ could protect against STZ-induced diabetic nephropathy by modulating the Nrf2/NOX2 signaling pathway.

Colchicine as potential inhibitor targeting MMP-9, NOX2 and TGF-β1 in myocardial infarction: a combination of docking and molecular dynamic simulation study

The global data revealed that myocardial infarction (MI) in coronary heart disease has been the leading cause of mortality worldwide in both developing and developed countries. The remodeling process after MI is essential to be the leading cause of heart failure due to cardiac remodeling. The evidence showed the increment of MMP-9, NOX2 and TGF-β1 expressions are biomarkers that influence cardiac remodeling. Lately, colchicine is widely used in the treatment of cardiovascular diseases. The effects of colchicine on NOX2, MMP-9 and TGF-β1 in the molecular models are still not yet discussed. We proposed a molecular docking and molecular dynamics simulation study to show the interaction between colchicine, NOX2, MMP-9 and TGF-β1. Colchicine has a good binding affinity with MMP-9, NOX2 and TGF-β1 based on the value, which are -8.3 Kcal/mol, -6.7 Kcal/mol and -6.5 Kcal/mol, respectively. Colchicine also binds to some catalytic residues in MMP-9, NOX2 and TGF-β1 that are responsible for inhibitor effects. The RMSD values between colchicine and MMP-9, NOX2 and TGF-β1 are 2.4 Å, 2 Å and 2.1 Å, respectively. The RMSF values of ligand and receptors complex showed relatively similar fluctuations. The SASA analysis showed that colchicine could create a more stable interaction with MMP-9. PCA analysis revealed that colchicine is capable of creating a solid and stable interaction with MMP-9 mainly, also NOX2 and TGF-β1. In conclusion, docking and molecular dynamics analysis showed evidence of colchicine roles in the inhibition of MMP-9, NOX2 and TGF-β1 in order to inhibit the remodeling process after MI.Communicated by Ramaswamy H. Sarma.

Chemical synthesis of a reported p47phox/p22phox inhibitor and characterization of its instability and irreproducible activity

The nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) multi-subunit complex is a highly abundant and central source of reactive oxygen species. NOX2 is a key enzyme of the innate immune system involved in antibacterial response, but excessive NOX2 activity is involved in oxidative stress and inflammation in many diseases. Inhibition of NOX2 has great potential as a therapeutic strategy. An intriguing pharmacological approach for inhibiting NOX2 is to target the p47phox subunit and thereby block the protein-protein interaction with p22phox, whereby assembling and activation of NOX2 is prevented. However, the shallow binding pocket of p47phox makes it difficult to develop drug-like p47phox/p22phox inhibitors. Recently, the small molecule LMH001 was reported to inhibit the p47phox/p22phox interaction, reduce endothelial NOX2 activity, and protect mice from angiotensin II-induced vascular oxidative stress. These noteworthy results could have significant impact on the field of NOX2 pharmacology, as specific and efficient inhibitors are scarce. Here, we synthesized and tested LMH001 to have it available as a positive control. We established a robust synthetic route for providing LMH001, but subsequently we experienced that LMH001 is chemically unstable in aqueous buffer. In addition, neither LMH001 nor its breakdown products were able to inhibit the p47phox/p22phox interaction in a non-cellular fluorescence polarization assay. However, LHM001 was a weak inhibitor of NOX2 in a functional cell assay, but with same low potency as one of its breakdown products. These findings question the activity and suggested mechanism of LMH001 and constitute important information for other researchers interested in chemical probes for studying NOX2 biology.

NOX2 and NOX5 are increased in cardiac microvascular endothelium of deceased COVID-19 patients

BACKGROUND

Cardiac injury and inflammation are common findings in COVID-19 patients. Autopsy studies have revealed cardiac microvascular endothelial damage and thrombosis in COVID-19 patients, indicative of microvascular dysfunction in which reactive oxygen species (ROS) may play a role. We explored whether the ROS producing proteins NOX2, NOX4 and NOX5 are involved in COVID-19-induced cardio-microvascular endothelial dysfunction.

METHODS

Heart tissue were taken from the left (LV) and right (RV) ventricle of COVID-19 patients (n = 15) and the LV of controls (n = 14) at autopsy. The NOX2-, NOX4-, NOX5- and Nitrotyrosine (NT)-positive intramyocardial blood vessels fractions were quantitatively analyzed using immunohistochemistry.

RESULTS

The LV NOX2+, NOX5+ and NT+ blood vessels fractions in COVID-19 patients were significantly higher than in controls. The fraction of NOX4+ blood vessels in COVID-19 patients was comparable with controls. In COVID-19 patients, the fractions of NOX2+, NOX5+ and NT+ vessels did not differ significantly between the LV and RV, and correlated positively between LV and RV in case of NOX5 (r = 0.710; p = 0.006). A negative correlation between NOX5 and NOX2 (r = -0.591; p = 0.029) and between NOX5 and disease time (r = -0.576; p = 0.034) was noted in the LV of COVID-19 patients.

CONCLUSION

We show the induction of NOX2 and NOX5 in the cardiac microvascular endothelium in COVID-19 patients, which may contribute to the previously observed cardio-microvascular dysfunction in COVID-19 patients. The exact roles of these NOXes in pathogenesis of COVID-19 however remain to be elucidated.

NOX2 oxidase inhibitor GSK2795039 possess antiviral activity against H1N1 influenza A virus in vitro and vivo

The continuous zoonotic circulation and reassortment potential of influenza A viruses (IAV) in nature represents an enormous public health threat to humans. Beside vaccination antivirals are needed to efficiently control spreading of the disease. The previous research has shown that NOX2 involved in IAV replication, but the detailed mechanism has not been reported. In the present study we investigated the roles of NOX2 in host inflammatory response and IAV replication using a novel inhibitor GSK2795039. The drug significantly reduced H1N1 virus induced NOX2 activity and ROS release in human lung epithelial cells. The results of time course experiments suggested that GSK2795039 inhibited an early post-entry step of viral infection. Concomitantly, there was a decreased expression of pro-inflammatory cytokines (tumor necrosis factor (TNF)-α, interferon (IFN)-β and interleukin (IL)-6) in NOX2 suppressed cells. In vivo, compared with control groups, suppression of NOX2 improved the survival rate of mice infected with H1N1 virus (42.9% in GSK2795039 treated mice versus >0% of control mice) and viral burden also decreased in the GSK2795039 treated group. Thus, our data demonstrated a critical role for NOX2 in the establishment of H1N1 infection and subsequent inflammatory reactions, which suggest that GSK2795039 may be a potential therapeutic drug for IAV infection.

KMT2B-dependent RFK transcription activates the TNF-α/NOX2 pathway and enhances ferroptosis caused by myocardial ischemia-reperfusion

Epigenetic regulation such as histone modification is implicated in the pathogenesis of myocardial ischemia/reperfusion injury (MIRI). Lysine-specific methyltransferase 2B (KMT2B) is a histone H3 lysine 4 (H3K4) methyltransferase. This study aims at exploring the role of KMT2B-mediated histone modification in MIRI. Peripheral blood samples were collected from 30 patients with acute myocardial infarction (AMI) and 30 healthy volunteers for analyses of the expression levels of KMT2B, riboflavin kinase (RFK), tumor necrosis factor (TNF)-α, and NADPH oxidase 2 (NOX2). H9C2 cardiomyocytes and Sprague-Dawley rats were utilized for developing in vitro and in vivo models. To evaluate the effects of the aforementioned molecules on cellular damage and MIRI, short hairpin RNAs or overexpression plasmids were introduced into cardiomyocytes for gene silencing or overexpression and also, they were packaged into adenovirus vectors for in vivo interventions. Immunoprecipitation assays were conducted to assess the interactions between KMT2B and RFK and among RFK, NOX2 sub-unit p22^phox, and TNF receptor 1-associated death domain protein. KMT2B, RFK, TNF-α, and NOX2 were notably upregulated in AMI patients. KMT2B knockdown resulted in considerably attenuated cell apoptosis and reduced myocardial infarct area. Additionally, the release of pro-inflammatory proteins and ferroptosis were suppressed. Furthermore, KMT2B could promote RFK gene transcription by upregulating H3 methylation levels and consequently activate the TNF-α/NOX2 axis, which was the possible mechanism underlying the role of KMT2B in MIRI. KMT2B motivates MIRI-induced cellular injury and ferroptosis by inducing RFK transcription and mediating the TNF-α/NOX2 axis.

CTRP1 Aggravates Cardiac Fibrosis by Regulating The NOX2/P38 Pathway in Macrophages

OBJECTIVE

C1q/TNF-related proteins 1 (CTRP1) is a recently identified adiponectin associated with obesity-linked disorders and adverse cardiovascular events. The effect of CTRP1 on cardiac fibrosis has not yet been fully elucidated; thus, we aimed to explore this association.

MATERIALS AND METHODS

In this experimental study, a mouse model of cardiac fibrosis was established by administering isoproterenol (ISO) (subcutaneously injecting 10 mg/kg/day for 3 days and then 5 mg/kg/day for 11 days). Mice were also injected with recombinant CTRP1 protein (200 μg/kg) 14 days after the final ISO administration. Adult mouse fibroblasts were isolated and stimulated with transforming growth factor (TGF) β1, followed by treatment with recombinant CTRP1. Primary bone marrow-derived macrophages were isolated from C57BL/6J mice and treated with recombinant CTRP1 as well.

RESULTS

CTRP1 level was increased in mouse plasma and heart tissue 2 weeks after ISO injection. Our findings indicated that recombinant CTRP1 injection aggravated ISO-induced cardiac fibrosis and dysfunction. However, recombinant CTRP1 did not alter TGFβ1-induced fibroblast proliferation and activation or collagen transcription. Recombinant CTRP1 exacerbated ISO-induced macrophage infiltration and inflammatory response. We determined that macrophages treated with recombinant CTRP1 showed increased pro-inflammatory cytokine release. Fibroblasts co-cultured with macrophages treated with recombinant CTRP1 showed increased proliferation and collagen transcription. We also found that CTRP1 upregulated the NADPH oxidase 2 (NOX2)/p38 pathway in macrophages. When we inhibited p38 signaling, the pro-inflammatory effect of CTRP1 on macrophages was counteracted. Fibroblasts co-cultured with macrophages treated with a p38 inhibitor also showed limited proliferation and collagen transcription.

CONCLUSION

Cardiac fibrosis was aggravated with the activation of the NOX2/p38 pathway in macrophages after CTRP1 treatment.

Specific inhibition of NADPH oxidase 2 modifies chronic epilepsy

Recent work by us and others has implicated NADPH oxidase (NOX) enzymes as main producers of reactive oxygen species (ROS) following a brain insult such as status epilepticus, contributing to neuronal damage and development of epilepsy. Although several NOX isoforms have been examined in the context of epilepsy, most attention has focused on NOX2. In this present study, we demonstrate the effect of gp91ds-tat, a specific competitive inhibitor of NOX2, in in vitro epileptiform activity model as well as in temporal lobe epilepsy (TLE) model in rats. We showed that in in vitro seizure model, gp91ds-tat modulated Ca²⁺ oscillation, prevented epileptiform activity-induced ROS generation, mitochondrial depolarization, and neuronal death. Administration of gp91ds-tat 1 h after kainic acid-induced status epilepticus significantly decreased the expression of NOX2, as well as the overall NOX activity in the cortex and the hippocampus. Finally, we showed that upon continuous intracerebroventricular administration to epileptic rats, gp91ds-tat significantly reduced the seizure frequency and the total number of seizures post-treatment compared to the scrambled peptide-treated animals. The results of the study suggest that NOX2 may have an important effect on modulation of epileptiform activity and has a critical role in mediating seizure-induced NOX activation, ROS generation and oxidative stress in the brain, and thus significantly contributes to development of epilepsy following a brain insult.

Telomere Shortening in Hypertensive Heart Disease Depends on Oxidative DNA Damage and Predicts Impaired Recovery of Cardiac Function in Heart Failure

BACKGROUND

Heart failure (HF) coincides with cardiomyocyte telomere shortening. Arterial hypertension is the most prominent risk factor for HF. Both HF and arterial hypertension are associated with dysregulation of the neurohormonal axis. How neurohormonal activation is linked to telomere shortening in the pathogenesis of HF is incompletely understood.

METHODS

Cardiomyocyte telomere length was assessed in a mouse model of hypertensive HF induced by excess neurohormonal activation (AngII [angiotensin II] infusion, high salt diet, and uninephrectomy), in AngII-stimulated cardiomyocytes and in endomyocardial biopsies from patients with HF. Superoxide production, expression of NOX2 (NADPH oxidase 2) and PRDX1 (peroxiredoxin 1) and HDAC6 (histone deacetylase 6) activity were assessed.

RESULTS

Telomere shortening occurred in vitro and in vivo, correlating with both left ventricular (LV) dilatation and LV systolic function impairment. Telomere shortening coincided with increased superoxide production, increased NOX2 expression, increased HDAC6 activity, loss of the telomere-specific antioxidant PRDX1, and increased oxidative DNA-damage. NOX2 knockout prevented PRDX1 depletion, DNA-damage and telomere shortening confirming this enzyme as a critical source of reactive oxygen species. Cotreatment with the NOX inhibitor apocynin ameliorated hypertensive HF and telomere shortening. Similarly, treatment with the HDAC6 inhibitor tubastatin A, which increases PRDX1 bioavailability, prevented telomere shortening in adult cardiomyocytes. To explore the clinical relevance of our findings, we examined endomyocardial biopsies from an all-comer population of patients with HF with reduced ejection fraction. Here, cardiomyocyte telomere length predicted the recovery of cardiac function.

CONCLUSIONS

Cardiomyocyte telomere shortening and oxidative damage in heart failure with reduced ejection fraction induced by excess neurohormonal activation depends on NOX2-derived superoxide and may help to stratify HF therapy.

The loss of pancreatic islet NADPH oxidase (NOX)2 improves islet transplantation

Islet transplantation is a promising treatment strategy for type 1 diabetes mellitus (T1DM) patients. However, oxidative stress-induced graft failure due to an insufficient revascularization is a major problem of this therapeutic approach. NADPH oxidase (NOX)2 is an important producer of reactive oxygen species (ROS) and several studies have already reported that this enzyme plays a crucial role in the endocrine function and viability of β-cells. Therefore, we hypothesized that targeting islet NOX2 improves the outcome of islet transplantation. To test this, we analyzed the cellular composition and viability of isolated wild-type (WT) and Nox2-/- islets by immunohistochemistry as well as different viability assays. Ex vivo, the effect of Nox2 deficiency on superoxide production, endocrine function and anti-oxidant protein expression was studied under hypoxic conditions. In vivo, we transplanted WT and Nox2-/- islets into mouse dorsal skinfold chambers and under the kidney capsule of diabetic mice to assess their revascularization and endocrine function, respectively. We found that the loss of NOX2 does not affect the cellular composition and viability of isolated islets. However, decreased superoxide production, higher glucose-stimulated insulin secretion as well as expression of nuclear factor erythroid 2-related factor (Nrf)2, heme oxygenase (HO)-1 and superoxide dismutase 1 (SOD1) was detected in hypoxic Nox2-/- islets when compared to WT islets. Moreover, we detected an early revascularization, a higher take rate and restoration of normoglycemia in diabetic mice transplanted with Nox2-/- islets. These findings indicate that the suppression of NOX2 activity represents a promising therapeutic strategy to improve engraftment and function of isolated islets.

Mycobacterium tuberculosis Utilizes Host Histamine Receptor H1 to Modulate Reactive Oxygen Species Production and Phagosome Maturation via the p38MAPK-NOX2 Axis

Tuberculosis (TB), which is caused by the single pathogenic bacterium, Mycobacterium tuberculosis, is among the top 10 lethal diseases worldwide. This situation has been exacerbated by the increasing number of cases of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB). Histamine is an organic nitrogenous compound that mediates a plethora of cell processes via different receptors. The expression of histamine receptor H1 (HRH1), one of the four histamine receptors identified to date was previously reported to be augmented by M. tuberculosis infection, although the underlying mechanism is unclear. In the present study, we applied confocal microscopy, flow cytometry, and Western blotting to show that HRH1 expression was enhanced in macrophages following mycobacterial infection. Furthermore, by combining techniques of gene knockdown, immunoprecipitation, intracellular bacterial burden analysis, fluorescence labeling, and imaging, we found that M. tuberculosis targeted the host HRH1 to suppress NOX2-mediated cROS production and inhibit phagosome maturation and acidification via the GRK2-p38MAPK signaling pathway. Our findings clarified the underlying mechanism of the M. tuberculosis and host HRH1 interaction and may provide useful information for the development of novel antituberculosis treatments.

Two major genes associated with autoimmune arthritis, Ncf1 and Fcgr2b, additively protect mice by strengthening T cell tolerance

A breach of T cell tolerance is considered as a major step in the pathogenesis of rheumatoid arthritis. In collagen-induced arthritis (CIA) model, immunization with type II collagen (COL2) leads to arthritis in mice through T cells responding to the immunodominant COL2_259–273 peptide. T cells could escape from thymus negative selection because endogenous COL2_259–273 peptide only weakly binds to the major histocompatibility complex class II (MHCII) molecule A^q. To investigate the regulation of T cell tolerance, we used a new mouse strain BQ.Col2^266E with homozygous D266E mutations in the Col2 gene leading to a replacement of the endogenous aspartic acid (D) to glutamic acid (E) at position 266 of the COL2_259–273 peptide, resulting in stronger binding to A^q. We also established BQ.Col2^264R mice carrying an additional K264R mutation changed the lysine (K) at position 264 to eliminate the major TCR recognition site. The BQ.Col2^266E mice were fully resistant to CIA, while the BQ.Col2^264R mice developed severe arthritis. Furthermore, we studied two of the most important non-MHCII genes associated with CIA, i.e., Ncf1 and Fcgr2b. Deficiency of either gene induced arthritis in BQ.Col2^266E mice, and the downstream effects differ as Ncf1 deficiency reduced Tregs and was likely to decrease expression of autoimmune regulator (AIRE) while Fcgr2b did not. In conclusion, the new human-mimicking mouse model has strong T cell tolerance to COL2, which can be broken by deficiency of Fcgr2b or Ncf1, allowing activation of autoreactive T cells and development of arthritis.

MiR-190 ameliorates glucotoxicity-induced dysfunction and apoptosis of pancreatic β-cells by inhibiting NOX2-mediated reactive oxygen species production

Glucotoxicity-induced pancreatic β-cell failure contributes to the development of type 2 diabetes mellitus (T2DM). Accumulating evidence reveals that miRNAs play a critical role in regulating pancreatic β-cell function and survival. In this study, we employed a self-assembled cell microarray (SAMcell)-based functional screening assay to identify miRNAs that are capable of regulating the dysfunction of β-cells induced by glucotoxicity. Among 62 conserved miRNAs we tested, miR-190 was identified as a candidate regulator that could effectively restore insulin expression in NIT-1 cells under high-glucose (HG) stimulation. Further analyses demonstrated that miR-190 was significantly down-regulated in HG-treated NIT-1 cells, as well as in the pancreas of diabetic mice. Mechanistic studies showed that Cybb is the direct target gene of miR-190, which encodes the gp91phox protein, a subunit of the NOX2 complex. Furthermore, both miR-190 overexpression and Cybb knockdown inhibited apoptosis and improved glucose-stimulated insulin secretion (GSIS) in HG-stimulated NIT-1 cells by attenuating the excessive production of reactive oxygen species (ROS). More importantly, a targeted delivery of mPEG-PCL-g-PDMAEMA nanoparticles/miR-190 complexes (PECgD NPs/miR-190) to the pancreas significantly ameliorated hyperglycemia, decreased fasting serum insulin levels, and improved glucose tolerance in diabetic mice. Taken together, our findings suggest that the miR-190/Cybb axis plays an important role in glucotoxicity-induced pancreatic β-cell failure. Restoring miR-190 expression levels may be a possible therapeutic strategy to protect β-cells in T2DM.

A novel synthetic peptide SVHRSP attenuates dopaminergic neurodegeneration by inhibiting NADPH oxidase-mediated neuroinflammation in experimental models of Parkinson's disease

Current treatment of Parkinson's disease (PD) ameliorates symptoms but fails to block disease progression. This study was conducted to explore the protective effects of SVHRSP, a synthetic heat-resistant peptide derived from scorpion venom, against dopaminergic neurodegeneration in experimental models of PD. Results showed that SVHRSP dose-dependently reduced the loss of dopaminergic neuron in the nigrostriatal pathway and motor impairments in both rotenone and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine/probenecid (MPTP/p)-induced mouse PD models. Microglial activation and imbalance of M1/M2 polarization were also abrogated by SVHRSP in both models. In rotenone-treated primary midbrain neuron-glial cultures, loss of dopaminergic neuron and microglial activation were mitigated by SVHRSP. Furthermore, lipopolysaccharide (LPS)-elicited microglial activation, M1 polarization and related dopaminergic neurodegeneration in primary cultures were also abrogated by SVHRSP, suggesting that inhibition of microglial activation contributed to SVHRSP-afforded neuroprotection. Mechanistic studies revealed that SVHRSP blocked both LPS- and rotenone-induced microglial NADPH oxidase (NOX2) activation by preventing membrane translocation of cytosolic subunit p47phox. NOX2 knockdown by siRNA markedly attenuated the inhibitory effects of SVHRSP against LPS- and rotenone-induced gene expressions of proinflammatory factors and related neurotoxicity. Altogether, SVHRSP protects dopaminergic neurons by blocking NOX2-mediated microglial activation in experimental PD models, providing experimental basis for the screening of clinical therapeutic drugs for PD.

Upregulation of p67phox in response to ischemia/reperfusion is cardioprotective by increasing ZIP2 expression via STAT3

While the zinc transporter ZIP2 (Slc39a2) is upregulated via STAT3 as an adaptive response to protect the heart from ischemia/reperfusion (I/R) injury, the precise mechanism underlying its upregulation remains unclear. The purpose of this study was to investigate the role of NADPH oxidase (NOX) isoform NOX2-derived ROS in the regulation of ZIP2 expression, focusing on the role of the NOX2 cytosolic factor p67^phox. Mouse hearts or H9c2 cells were subjected to I/R. Protein expression was detected with Western blotting. Infarct size was measured with TTC staining. The cardiac-specific p67^phox conditional knockout mice (p67^phox cKO) were generated by adopting the CRISPR/Cas9 system. I/R-induced upregulation of STAT3 phosphorylation and ZIP2 expression was reversed by the ROS scavenger N-acetylcysteine (NAC) and the NOX inhibitor diphenyleneiodonium (DPI). p67^phox but not NOX2 expression was increased 30 min after the onset of reperfusion, and downregulation of p67^phox by siRNA or cKO invalidated I/R-induced upregulation of STAT3 phosphorylation and ZIP2 expression. Both NAC and DPI prevented upregulation of STAT3 phosphorylation and ZIP2 expression induced by overexpression of p67^phox, whereas the STAT3 inhibitor stattic abrogated upregulation ZIP2 expression, indicating that the increase of p67^phox at reperfusion is an upstream signaling event responsible for ZIP2 upregulation via STAT3. Experiments also showed that chelation of Zn²⁺ markedly enhanced p67^phox and ZIP2 expression as well as STAT3 phosphorylation, whereas supplementation of Zn²⁺ had the opposite effects, indicating that cardiac Zn²⁺ loss upon reperfusion triggers p67^phox upregulation. Furthermore, ischemic preconditioning (IPC) upregulated ZIP2 via p67^phox, and cKO of p67^phox aggravated cardiac injury after I/R, indicating that p67^phox upregulation is cardioprotective against I/R injury. In conclusion, an increase of p67^phox expression in response to Zn²⁺ is an intrinsic adaptive response to I/R and leads to cardioprotection against I/R by upregulating ZIP2 via STAT3.

Prednisone Ameliorates Atrial Inflammation and Fibrosis in Atrial Tachypacing Dogs

Atrial inflammation and fibrosis have long been considered culprits in the development of atrial fibrillation (AF). Prior clinical studies showed that corticosteroid therapy is beneficial in patients with AF. Here we sought to determine whether prednisone treatment prevents atrial tachypacing (ATP) induced atrial fibrosis.Dogs were randomized into the sham, ATP, ATP + low-dose prednisone (ALP), and ATP + high-dose prednisone (AHP) groups. After 6 days of recovery from surgery, dogs were subjected to ATP at 400 beats per minute for 4 weeks while being treated with prednisone (15 or 40 mg/day) or a placebo. Pacemakers were not activated in the sham group.Compared with the ATP group, the expression of collagen I, collagen III, α-smooth muscle actin, transforming growth factor-β1 and connective tissue growth factor were significantly reduced in the ALP and AHP groups. Fluorescence assays showed that reactive oxygen species formation in the right atrium was suppressed in the ALP and AHP groups compared with the ATP group. The protein level of NADPH oxidase 2 was reduced in the ALP and AHP groups' versus ATP group, while NOX4 and NOX5 were unchanged. ATP-induced downregulation of BH4 and eNOS uncoupling in the atria was partially restored in the prednisone-treated groups.Our study demonstrated that atrial fibrosis induced by ATP were suppressed by prednisone. Low-dose prednisone was also effective in suppressing the development of atrial fibrosis.

Liraglutide inhibits receptor for advanced glycation end products (RAGE)/reduced form of nicotinamide-adenine dinucleotide phosphate (NAPDH) signaling to ameliorate non-alcoholic fatty liver disease (NAFLD) in vivo and vitro

The study was designed to investigate the effects of liraglutide and reveal its action mechanism associated with RAGE/NAPDH in NAFLD. The liver tissue was collected for HE, Masson, and ROS staining. Apoptosis levels were detected through TUNEL staining and ROS levels were evaluated through ROS staining. The expression levels of c-Jun N-terminal kinase (JNK) and transforming growth factor-β (TGF-β) were detected through Western blot. JNK and the expression of Collagenα1, Collagenα2 and connective tissue growth factor (CTGF) were detected through RT-qPCR and Western blot and the expression in mouse liver stellate cells (JS-1) cells were evaluated through immunofluorescence staining. We detected the effects of liraglutide on NAFLD in high-fat diet (HFD)-fed mice. Liraglutide treatment improved bridging fibrosis and liver function, as well as lessening ROS levels and the protein levels of RAGE, NOX1, NOX2 and NOX4. In PA and H2O2-induced AML12 cells, liraglutide treatment was able to decrease cell apoptosis, ROS levels and the levels of inflammatory factors including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6, while it effects were reversed by the induction of RAGE overexpression or NOX2 overexpression. In JS-1 cells treated with medium culturing AML12 cells, liraglutide markedly suppressed cell proliferation and activation, while RAGE overexpression or NOX2 overexpression blunted these effects of liraglutide. Taken together, liraglutide exerts a protective role in improving liver injury caused by HFD, which could be related to decreased apoptosis and oxidative stress of liver cells, as well as decreased proliferation and activation of hepatic stellate cells through RAGE/NOX2.

Outgrowth endothelial progenitor cells restore cerebral barrier function following ischaemic damage: the impact of NOX2 inhibition

Disruption of blood-brain barrier (BBB), formed mainly by human brain microvascular endothelial cells (HBMECs), constitutes the major cause of mortality following ischaemic stroke. This study investigates whether OECs (outgrowth endothelial cells) can restore BBB integrity and function following ischaemic damage, and how inhibition of NOX2, a main source of vascular oxidative stress, affects the characteristics of BBB established with OECs and HBMECs in ischaemic settings. In vitro models of human BBB were constructed by co-culture of pericytes and astrocytes with either OECs or HBMECs before exposure to oxygen-glucose deprivation (OGD) alone or followed by reperfusion (OGD+R) in the absence or presence of NOX2 inhibitor, gp91ds-tat. The function and integrity of BBB were assessed by measurements of paracellular flux of sodium fluorescein (NaF) and transendothelial electrical resistance (TEER), respectively. Treatment with OECs during OGD+R effectively restored BBB integrity and function. Compared to HBMECs, OECs possessed lower NADPH oxidase activity, superoxide anion levels, and had greater total antioxidant capacity during OGD and OGD+R. Inhibition of NADPH oxidase during OGD and OGD+R restored the integrity and function of BBB established by HBMECs. This was evidenced by reductions in NADPH oxidase activity and superoxide anion levels. In contrast, treatment with gp91ds-tat aggravated ischaemic injury-induced BBB damage constructed by OECs. In conclusion, OECs are more resistant to ischaemic conditions and can effectively repair cerebral barrier following ischaemic damage. Suppression of oxidative stress through specific targeting of NOX2 requires close attention while using OECs as therapeutics.

NOX2-Induced High Glycolytic Activity Contributes to the Gain of COL5A1-Mediated Mesenchymal Phenotype in GBM

Simple Summary

Glioblastoma multiforme (GBM) is the most aggressive type of glioma and exhibits extensive heterogeneity and poor prognosis with a high recurrence rate. Among the genetic alterations in GBM with different phenotypic states, a mesenchymal subtype has been associated with a worse outcome in patients with GBM. The mechanisms for the gain of the mesenchymal subtype in GBM remain unclear. Our aim was to investigate whether NOX2-induced high glycolytic activity could contribute to the gain of the mesenchymal phenotype in GBM. We revealed that NOX2-induced high glycolytic activity can induce the gain of the COL5A1-mediated mesenchymal phenotype in GBM. Our findings will provide the molecular mechanism by which NOX2 contributes to the gain of mesenchymal phenotype in GBM.

Abstract

The alteration of the cellular metabolism is a hallmark of glioma. The high glycolytic phenotype is a critical factor in the pathogenesis of high-grade glioma, including glioblastoma multiforme (GBM). GBM has been stratified into three subtypes as the proneural, mesenchymal, and classical subtypes. High glycolytic activity was found in mesenchymal GBM relative to proneural GBM. NADPH oxidase 2 (NOX2) has been linked to cellular metabolism and epithelial-mesenchymal transition (EMT) in tumors. The role of NOX2 in the regulation of the high glycolytic phenotype and the gain of the mesenchymal subtype in glioma remain unclear. Here, our results show that the levels of NOX2 were elevated in patients with GBM. NOX2 induces hexokinase 2 (HK2)-dependent high glycolytic activity in U87MG glioma cells. High levels of NOX2 are correlated with high levels of HK2 and glucose uptake in patients with GBM relative to benign glioma. Moreover, NOX2 increases the expression of mesenchymal-subtype-related genes, including COL5A1 and FN1 in U87MG glioma cells. High levels of NOX2 are correlated with high levels of COL5A1 and the accumulation of extracellular matrix (ECM) in patients with GBM relative to benign glioma. Furthermore, high levels of HK2 are correlated with high levels of COL5A1 in patients with GBM relative to benign glioma. Our results suggest that NOX2-induced high glycolytic activity contributes to the gain of the COL5A1-mediated mesenchymal phenotype in GBM.