Polymorphisms of the NADPH oxidase P22PHOX gene in a Caucasian population with intracranial aneurysms

Association of single nucleotide polymorphisms in the CYBA gene with coal workers' pneumoconiosis in the Han Chinese population

Coal workers' pneumoconiosis (CWP) is caused by long-term exposure to inhaled coal dust; it is likely influenced by the interaction between environmental factors and multiple susceptibility genes, such as the CYBA (cytochrome b-245α polypeptide) gene that has recently been identified to be involved in the genetic susceptibility for several pulmonary diseases. The aim of this case-control study was to explore the association between CYBA gene polymorphisms and the development of CWP in coal miners belonging to the Han ethnic group in China. Single nucleotide polymorphisms (SNPs) rs7195830, rs13306296, rs4673, rs9932581, and rs16966671 of the CYBA gene were analyzed in CWP patients (n = 652) and dust-exposed control subjects (n = 648) using the matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) on the Sequenom MassARRAY® platform (Sequenom, San Diego, CA, USA). Results from the present study showed a strong allele association between CWP patients and the CYBA SNP rs7195830 polymorphism (p < .001, OR = 1.550). Using the additive and the dominant model, the CYBA SNP rs7195830 polymorphism also showed significant associations with CWP patients (p < .001, OR = 1.621; p = .003, OR = 1.711, respectively). No statistically significant difference was demonstrated in either the allele or genotype frequencies of the other four examined SNPs (rs13306296, rs4673, rs9932581, and rs16966671) between the CWP group and dust-exposed control group (all p > .05). The present study is the first to have demonstrated an association between CYBA (rs7195830) polymorphism and the risk of developing CWP in subjects belong to the Han ethnic group in China and provides further clues for research into the pathogenesis of CWP.

The active participation of p22phox-214T/C in the formation of intracranial aneurysm and the suppressive potential of edaravone

Oxidative stress reactions play an important role in the pathogenesis of intracranial aneurysm (IA). p22phox is involved in the oxidative stress reaction, and it is a critical subunit of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. The present study investigated the association of genetic variants within the gene encoding p22phox‑214T/C with IA. The p22phox‑214T/C gene polymorphisms in 192 cases of IA and 112 controls were analyzed by polymerase chain reaction‑restriction fragment length polymorphism (PCR‑RFLP). The mRNA expression of NADPH oxidase was also analyzed by RT‑PCR. The results of RT‑PCR were validated by ELISA. In a rabbit model of elastase‑induced aneurysm, we used edaravone for anti‑oxidative stress treatment to observe the curative effects. In the clinical cases, a significant difference in p22phox‑214T/C allele frequencies in the IA group was observed compared with the control group (P<0.001). The expression level of NADPH oxidase was differed significantly between the IA group and the control group. In the rabbit model of elastase‑induced aneurysm, the success rate of the aneurysmal model in the edaravone group and the wound ulcer rate were lower than those in the control group. In addition, the diameter of the aneurysm was smaller than in the edaravone group than in the control group (3.26±0.13 mm vs. 3.85±0.07 mm), and the expression of matrix metalloproteinase‑9 (MMP‑9) was significantly lower than that in the control group (P<0.0001). Thus, these data suggest the active participation of p22phox‑214T/C in the formation of IA and the suppressive potential of edaravone against IA formation.

NADPH oxidase p22phox C242T polymorphism is associated with macroalbuminuria in diabetic patients: A meta-analysis

AIMS

Previous studies suggested an association between C242T polymorphism in NADPH Oxidase p22phox and diabetic nephropathy (DN) risk, but the results were inconsistent. To obtain a more precise estimation, we carried out a meta-analysis to analyze the effect of C242T polymorphism in NADPH Oxidase p22phox on DN risk.

METHODS

We searched PubMed, ISI Web of Science, and China National Knowledge Infrastructure for all eligible case-control studies through May 2016. The odds ratios (ORs), together with the 95% confidence intervals (CIs), were calculated to evaluate the strength of association between C242T SNP in NADPH Oxidase p22phox on DN risk.

RESULTS

Overall, ten eligible studies involving a total of 1894 cases and 1746 controls were included in our meta-analysis. The results showed that there was no statistical evidence of association between NADPH oxidase p22phox C242T polymorphism and DN in all genetic models (T vs. C: OR 1.16, 95% CI 0.85-1.59, p=0.34; TT vs. CC: OR 1.49, 95% CI 0.80-2.76, p=0.21; TT/CT vs. CC: OR 1.18, 95% CI 0.81-1.72, p=0.40; TT vs.

CT/CC

OR 1.31, 95% CI 0.82-2.11, p=0.26). However, significant association was found in diabetic patients with macroalbuminuria.

CONCLUSION

This meta-analysis indicates that NADPH oxidase p22phox C242T polymorphism is associated with macroalbuminuria in diabetic patients. However, this conclusion should be interpreted with caution due to the small sample size. Larger sample-size studies with homogeneous patients and well-matched controls are required.

15-Deoxy-∆12,14-PGJ 2, by activating peroxisome proliferator-activated receptor-gamma, suppresses p22phox transcription to protect brain endothelial cells against hypoxia-induced apoptosis

15-Deoxy-∆(12,14)-PGJ(2) (15d-PGJ(2)) and thiazolidinedione attenuate reactive oxygen species (ROS) production via a peroxisome proliferator-activated receptor-gamma (PPAR-γ)-dependent pathway. Nonetheless, how PPAR-γ mediates ROS production to ameliorate ischemic brain injury is not clear. Recent studies indicated that nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is the major source of ROS in the vascular system. In the present study, we used an in vitro oxygen-glucose deprivation and reoxygenation (hypoxia reoxygenation [HR]) paradigm to study whether PPAR-γ interacts with NADPH oxidase, thereby regulating ROS formation in cerebral endothelial cells (CECs). With pharmacological (PPAR-γ antagonist GW9662), loss-of-function (PPAR-γ siRNA), and gain-of-function (Ad-PPAR-γ) approaches, we first demonstrated that 15d-PGJ(2) protected HR-treated CECs against ROS-induced apoptosis in a PPAR-γ-dependent manner. Results of promoter and subcellular localization analyses further revealed that 15d-PGJ(2), by activating PPAR-γ, blocked HR-induced NF-κB nuclear translocation, which led to inhibited transcription of the NADPH oxidase subunit p22phox. In summary, we report a novel transrepression mechanism whereby PPAR-γ downregulates hypoxia-activated p22phox transcription and the subsequent NADPH oxidase activation, ROS formation, and CEC apoptosis.

Association between NADPH oxidase p22(phox) C242T polymorphism and ischemic cerebrovascular disease: a meta-analysis

Background

Epidemiological studies have evaluated the association between nicotinamide adenine dinucleotide phosphate (NADPH) oxidase p22^phox C242T polymorphism and risk of ischemic cerebrovascular disease (ICVD), but the results remain inconclusive. This meta-analysis was therefore designed to clarify these controversies.

Methodology/Principal Findings

Systematic searches of electronic databases Embase, PubMed and Web of Science, as well as hand searching of the references of identified articles and the meeting abstracts were performed. Statistical analyses were performed using software Review Manager (Version 5.1.7) and Stata (Version 11.0). The pooled odds ratios (ORs) with 95% confidence intervals (95%CIs) were performed. Fixed or random effects model was separately used depending on the heterogeneity between studies. Publication bias was tested by Begg's funnel plot and Egger's regression test. A total of 6 studies including 1,948 cases and 2,357 controls were combined showing no statistical evidence of association between NADPH oxidase p22^phox C242T polymorphism and overall ICVD (allelic model: OR = 1.08, 95%CI = 0.93–1.26; additive model: OR = 1.33, 95%CI = 0.81–2.17; dominant model: OR = 1.00, 95%CI = 0.86–1.15; recessive model: OR = 1.06, 95%CI = 0.77–1.45). Significant association was found in large-artery atherosclerotic stroke subgroup (allelic model: OR = 1.12, 95%CI = 0.88–1.41; additive model: OR = 1.36, 95%CI = 0.60–3.09; dominant model: OR = 1.25, 95%CI = 0.74–2.11; recessive model: OR = 2.17, 95%CI = 1.11–4.23). No statistical evidence of significant association was observed for small-vessel occlusive stroke, as well as Asian subgroup and Caucasian subgroup. Statistical powers on the combined sample size (total and subgroup) were all lower than 80%.

Conclusions/Significance

This meta-analysis indicates that NADPH oxidase p22^phox C242T polymorphism is more associated with large-artery atherosclerotic stroke than small-vessel occlusive stroke. However, this conclusion should be interpreted with caution due to the small sample size. Larger sample-size studies with homogeneous ICVD patients and well-matched controls are required.

NAD(P)H oxidase and pro-inflammatory response during maximal exercise: role of C242T polymorphism of the P22PHOX subunit

Intense exercise induces a pro-inflammatory status through a mechanism involving the NAD(P)H oxidase system. We focused our attention on p22phox, a subunit of the NAD(P)H oxidase, and on its allelic polymorphism C242T, which is known to affect the functional activity of the enzyme. We investigated whether the p22phox C242T variants exhibit systemic effects in healthy subjects by analyzing the proinflammatory and cardiocirculatory responses to physical exercise in endurance athletes. The group of study consisted of 97 long distance runners, 37 +/- 4.4 yrs of age, with similar training history. The subjects underwent a maximal stress test during which both inflammatory and cardiopulmonary parameters were monitored. Our results demonstrate that T allele deeply influences the neutrophil activation in response to intense exercise, since T carriers were characterized by significantly lower release of myeloperoxidase (MPO), a classical leukocyte derived pro-inflammatory cytokine. In addition, the presence of T allele was associated with a higher cardiopulmonary efficiency as evidenced by a significantly lower Heart Rate (HR) at the peak of exercise and, when a dominant model was assumed, by a higher maximal oxygen uptake (VO2 max). On the other hand, no effects of 242T mutation on the plasmatic total antioxidant capacity (TAC) and on the cortisol responses to the physical exercise were detected. In conclusion, our data support a systemic role for p22phox C242T polymorphism that, modifying the intensity of the inflammatory response, can influence the cardiovascular adaptations elicited by aerobic training. These results contribute to support the hypothesis of a systemic effect for the C242T polymorphism and of its possible functional rebound in healthy subjects.

NOX enzymes in the central nervous system: from signaling to disease

Oxidative stress has been implicated in the pathogenesis of neurologic and psychiatric diseases. The brain is particularly vulnerable to oxidative damage due to high oxygen consumption, low antioxidant defense, and an abundance of oxidation-sensitive lipids. Production of reactive oxygen species (ROS) by mitochondria is generally thought to be the main cause of oxidative stress. However, a role for ROS-generating NADPH oxidase NOX enzymes has recently emerged. Activation of the phagocyte NADPH oxidase NOX2 has been studied mainly in microglia, where it plays a role in inflammation, but may also contribute to neuronal death in pathologic conditions. However, NOX-dependent ROS production can be due to the expression of other NOX isoforms, which are detected not only in microglia, but also in astrocytes and neurons. The physiologic and pathophysiologic roles of such NOX enzymes are only partially understood. In this review, we summarize the present knowledge about NOX enzymes in the central nervous system and their involvement in neurologic and psychiatric diseases.

Oxidative stress and cardiovascular disease: novel tools give (free) radical insight

Cardiovascular disease is the most common cause of mortality in the Western world and accounts for up to a third of all deaths worldwide. Cardiovascular disease is multifactorial and involves complex interplay between lifestyle (diet, smoking, exercise, ethanol consumption) and fixed (genotype, age, menopausal status, gender) causative factors. The initiating step in cardiovascular disease is endothelial damage, which exposes these cells and the underlying cell layers to a deleterious inflammatory process which ultimately leads to the formation of atherosclerotic lesions. Intrinsic to lesion formation is cellular oxidative stress, due to the production of damaging free radicals (reactive oxygen and nitrogen species) by many cell types including endothelial cells, vascular smooth muscle cells and monocytes/macrophages. Exogenous factors such as smoking and the existence of other disease states such as diabetes also contribute to oxidative stress and are strong risk factors for cardiovascular disease. In this review we describe this role of free radicals in atherosclerosis and discuss the mechanisms and cellular systems by which these radicals are produced. We also highlight recent technological advances which have added to the vascular biologist's armoury and which promise to provide new insight into the role of reactive oxygen species in cardiovascular disease.

Molecular Genetics of Human Intracranial Aneurysms

Intracranial aneurysms (IAs) are the dilatations of blood vessels in the brain and pose potential risk of rupture leading to subarachnoid hemorrhage. Although the genetic basis of IAs is poorly understood, it is well-known that genetic factors play an important part in the pathogenesis of IAs. Therefore, the identifying susceptible genetic variants might lead to the understanding of the mechanism of formation and rupture of IAs and might also lead to the development of a pharmacological therapy. To elucidate the molecular pathogenesis of diseases has become a crucial step in the development of new treatment strategies. Although extensive genetic research and its potential implications for future prevention of this often fatal condition are urgently needed, efforts to elucidate the susceptibility loci of IAs are hindered by the issues bewildering the most common and complex genetic disorders, such as low penetrance, late onset, and uncertain modes of inheritance. These efforts are further complicated by the fact that many IA lesions remain asymptomatic or go undiagnosed. In this review, we present and discuss the current status of genetic studies of IAs and we recommend comprehensive genome-wide association studies to identify genetic loci that underlie this complex disease.

NADPH oxidase CYBA polymorphisms, oxidative stress and cardiovascular diseases

Oxidative stress plays a key role in the pathophysiology of several major cardiovascular diseases, including atherosclerosis, hypertension, heart failure, stroke and diabetes. ROS (reactive oxygen species) affect multiple tissues either directly or through NO depletion. ROS induce cardiovascular dysfunction by modulating cell contraction/dilation, migration, growth/apoptosis and extracellular matrix protein turnover, which contribute to vascular and cardiac remodelling. Of the several sources of ROS within the cardiovascular system, a family of multisubunit NADPH oxidases appears to be a predominant contributor of superoxide anion. Recent findings suggest a significant role of the genetic background in NADPH oxidase regulation. Common genetic polymorphisms within the promoter and exonic sequences of CYBA, the gene that encodes the p22(phox) subunit of NADPH oxidase, have been characterized in the context of cardiovascular diseases. This review aims to present the current state of research into these polymorphisms in their relationship to cardiovascular diseases.

TUMOR NECROSIS FACTOR-α GENE AND CEREBRAL ANEURYSMS

OBJECTIVE

The pathogenesis of intracranial aneurysms is still uncertain. In addition to atherosclerosis, immunological factors may play a role in the disease. Recent studies have suggested that tumor necrosis factor-alpha (TNF-alpha), one of the main proinflammatory cytokines, may play a key role in the formation and rupture of cerebral aneurysms. The purpose of this study is to evaluate the association of a functionally active polymorphism (-308 G<A) in the TNF-alpha gene with the risk and the clinical features of aneurysmal subarachnoid hemorrhage.

METHODS

A total of 171 consecutive aneurysmal subarachnoid hemorrhage patients and 144 healthy controls were involved in the study. Computed tomographic scan findings were assessed by Fisher grade; clinical neurological assessment was performed using the Hunt and Hess grading system. Patients and controls were genotyped for the-308 biallelic (G<A) polymorphism of the TNF-alpha gene.

RESULTS

The TNF-alpha G allele was significantly more frequent in patients than in controls (chi2 = 5.59; P = 0.0181) and homozygosity for the G allele, compared with remaining genotypes, was associated with a significantly increased risk of aneurysmal subarachnoid hemorrhage (odds ratio = 2.20; 95% confidence interval = 1.29<odds ratio<3.75). Allelic and genotypic frequencies of the examined polymorphism were not significantly different in disease subgroups. The different TNF-alpha genotypes do not seem to significantly modify the main clinical features of the disease.

CONCLUSION

Our data suggests that the TNF-alpha gene or a linked locus significantly modulates the risk for aneurysmal subarachnoid hemorrhage. Additional studies in different populations are warranted to confirm our findings.

The NOX family of ROS-generating NADPH oxidases: physiology and pathophysiology

For a long time, superoxide generation by an NADPH oxidase was considered as an oddity only found in professional phagocytes. Over the last years, six homologs of the cytochrome subunit of the phagocyte NADPH oxidase were found: NOX1, NOX3, NOX4, NOX5, DUOX1, and DUOX2. Together with the phagocyte NADPH oxidase itself (NOX2/gp91(phox)), the homologs are now referred to as the NOX family of NADPH oxidases. These enzymes share the capacity to transport electrons across the plasma membrane and to generate superoxide and other downstream reactive oxygen species (ROS). Activation mechanisms and tissue distribution of the different members of the family are markedly different. The physiological functions of NOX family enzymes include host defense, posttranlational processing of proteins, cellular signaling, regulation of gene expression, and cell differentiation. NOX enzymes also contribute to a wide range of pathological processes. NOX deficiency may lead to immunosuppresion, lack of otoconogenesis, or hypothyroidism. Increased NOX activity also contributes to a large number or pathologies, in particular cardiovascular diseases and neurodegeneration. This review summarizes the current state of knowledge of the functions of NOX enzymes in physiology and pathology.

The genetics of intracranial aneurysms

The rupture of an intracranial aneurysm (IA) leads to a subarachnoid hemorrhage, a sudden onset disease that can lead to severe disability and death. Several risk factors such as smoking, hypertension and excessive alcohol intake are associated with subarachnoid hemorrhage. IAs, ruptured or unruptured, can be treated either surgically via a craniotomy (through an opening in the skull) or endovascularly by placing coils through a catheter in the femoral artery. Even though the etiology of IA formation is mostly unknown, several studies support a certain role of genetic factors. In reports so far, genome-wide linkage studies suggest several susceptibility loci that may contain one or more predisposing genes. Studies of several candidate genes report association with IAs. To date, no single gene has been identified as responsible for IA formation or rupture. The identification of susceptible genes may lead to the understanding of the mechanism of formation and rupture and possibly lead to the development of a pharmacological therapy.

Nicotinamide adenine dinucleotide phosphate oxidase: a promiscuous therapeutic target for cardiovascular drugs?

The increased expression and activity of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex has emerged as a major common factor in the etiology of all forms of cardiovascular diseases since the upregulation of intravascular NADPH oxidase results in the formation of superoxide (O(2)(-)), which in turn promotes vasculopathy. An ever-increasing number of drugs commonly used in cardiovascular medicine have been shown to influence NADPH oxidase expression and activity. These include nitric oxide donors, nitroaspirin, eicosanoids, phosphodiesterase inhibitors, corticosteroids, antioxidants, and specific inhibitors. The objective of this review is to discuss these drugs in relation to the mechanisms underlying their effects on NADPH oxidase activity and the expression and therapeutic implications of these effects.

NADPH oxidase p22phox gene variants are associated with systemic oxidative stress biomarker responses to exercise training

Systemic oxidative stress plays a role in many degenerative diseases. Although regular physical activity has been known as the most effective nonpharmacological intervention to alleviate the oxidative stress, the beneficial effect varies between individuals. We investigated whether NADPH oxidase p22phox gene C242T and A640G polymorphisms are associated with systemic oxidative stress level response to exercise training (ExTr). Fifty-nine sedentary middle-aged to older Caucasians with relatively high cardiovascular disease risk factors underwent a 6-mo standardized ExTr program. Body mass index, plasma lipoprotein-lipid profiles, cardiovascular fitness, and plasma thiobarbituric acid reactive substances (TBARS) were measured before and after ExTr. Demographic and initial levels of cardiovascular disease risk factors were similar among genotype groups for both polymorphisms. Overall, TBARS was decreased by 16% with ExTr in the entire group ( P < 0.001). There was no significant difference in TBARS changes with ExTr among the C242T genotype groups. However, A allele carriers showed greater reduction in TBARS than noncarriers at the A640G locus ( P = 0.05). There was a significant interaction ( P = 0.05) between ExTr and A640G polymorphism in TBARS changes with ExTr. This interaction remained after accounting for age and baseline TBARS level. Furthermore, diplotype analysis showed that TBARS was decreased to a greater extent in the C242/A640 haplotype carriers compared with the noncarriers ( P < 0.05). We found that p22phox polymorphisms, especially A640G, were associated with differential changes in systemic oxidative stress with aerobic exercise training.

Oxidative stress and cardiovascular risk: the role of vascular NAD(P)H oxidase and its genetic variants

Several risk factors for coronary artery disease (CAD) induce atherosclerosis through endothelial activation and dysfunction, and ample evidence now suggests that the balance between production and removal of reactive oxygen species (ROS) - a condition termed oxidative stress - is implicated in such processes. A main source of ROS in vascular cells is the reduced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase system. This is a membrane-associated enzyme, composed of five subunits, catalyzing the one-electron reduction of oxygen, using NADH or NADPH as the electron donor. One of the system subunits, termed p22-phox, has a polymorphic site on exon 4, associated with variable enzyme activity. This polymorphism is generated by a point mutation (C(242)T) producing a substitution of histidine with tyrosine at position 72, which affects one of the heme binding sites essential for the NAD(P)H enzyme activity. The consequent decrease of superoxide production thus characterizes a phenotype candidate for conferring to the carrier a reduced susceptibility to CAD. At present, however, the body of evidence from current literature is not yet sufficient to confirm or exclude the hypothesis that the C(242)T polymorphism protects from CAD. The functional effects of this polymorphism and the potential and its pathophysiological consequences also need further investigation.