Role for Functional SOD2 Polymorphism in Pulmonary Arterial Hypertension in a Chinese Population

Modifiable risk factors, oxidative stress markers, and SOD2 rs4880 SNP in coronary artery disease: an association study

BACKGROUND

Coronary artery disease (CAD) has been linked to single nucleotide polymorphism (SNP) in superoxide dismutase 2 (SOD 2) gene. Additionally, several modifiable risk factors are also known to influence the CAD risk.

AIM

To investigate the association between selected modifiable risk factors and oxidative stress markers with the SOD2 rs4880 SNP in CAD patients.

METHODS

A cohort of 150 angiographically confirmed CAD patients, and 100 control subjects in the same geographic area were enrolled. SOD levels and lipid peroxidation were assessed in the blood samples using standard protocols. The genotyping of the SOD2 gene was conducted through the PCR-sequencing method.

RESULTS

This study indicated that CAD patients with the rs4880 SNP having heterozygous AG and mutated homozygous GG genotypes have increased oxidative stress, decreased SOD activity, and a positive association with CAD risk (OR 2.85) in comparison with control individuals. The investigation among CAD patients was then carried out based on modifiable risk factors. The risk factors selected were clinical characteristics, physical habits, nutritional status, and body mass index. In all the cases, MDA levels showed a positive association, and SOD activity showed a negative association with the selected polymorphism.

CONCLUSIONS

The study suggests that the selected modifiable risk factors have an important role in the higher oxidative stress found in patients, which may lead to SOD2 polymorphism. It also suggests that the SOD2 locus can be identified as a marker gene for CAD susceptibility.

Association of CYBA C242T and superoxide dismutase 2 A16V genetic variants with preeclampsia

OBJECTIVE

To investigate the relationship between NADPH oxidase p22phox subunit (CYBA; C242T) and superoxide dismutase 2 (SOD2; A16V) polymorphisms and the risk of preeclampsia (PE) in Chinese women.

METHODS

This case-control study included 325 patients with PE and 1294 controls. The genotypes were determined by polymerase chain reaction-restriction fragments length polymorphism method. Clinical, metabolic, and oxidative stress parameters were analyzed.

RESULTS

Participants with T allele of the CYBA C242T polymorphism had a decreased risk of PE (OR = 0.62, 95% CI: 0.42-0.92, P = 0.016) and those with the A allele of the SOD2 A16V polymorphism had increased risk of PE (OR = 1.44, 95% CI: 1.09-1.89, P = 0.010). The coexistence of the SOD2 AA + AV genotypes and the CYBA CC genotype further increased the risk of PE (OR = 2.32, 95% CI: 1.31-4.10, P = 0.003) when the CT + TT/VV combined genotype was the reference category.

CONCLUSION

The T allele of the CYBA C242T polymorphism is related to a decreased risk of PE, while the A allele of the SOD2 A16V polymorphism and its combination with the CYBA CC genotype are associated with an increased risk of PE in Chinese women.

Influences of the polymorphisms of the Sod2 gene (rs4880) on the motility and vigor of X- and Y-bearing sperm at different pH values

Superoxide dismutase 2 (SOD2) is an antioxidant enzyme that appears phylogenetically conserved. However, functional Sod2 polymorphisms have been studied, and the specific polymorphisms are related to activity alterations of the SOD2 enzyme. An example of a polymorphism of SOD2 is Val16Ala (rs4880), which has been identified in exon 2 of the human Sod2 gene. This polymorphism is recognized as a single nucleotide polymorphism (SNP) and alters the conformation of SOD2. Additionally, recent studies have shown that the Ala16 Val polymorphism in Sod2 can be related to different pathological diseases. In these terms, the objective of the present study was to evaluate whether the polymorphism of SOD2 in Val16Ala (rs4880) influences the motility and vigor of X- and Y-bearing sperm at different pH values promoting sperm selection. We found that polymorphism rs4880 at normal pH conditions can result in alterations in the activity of superoxide dismutase in the sperm through different assay analyses. Moreover, compelling modulation evidence indicates that this effect could also mediate seminal plasma redox alterations and consequently can play an important role in sperm physiology, fertilization, and postfertilization.

Riding the tiger - physiological and pathological effects of superoxide and hydrogen peroxide generated in the mitochondrial matrix

Elevated mitochondrial matrix superoxide and/or hydrogen peroxide concentrations drive a wide range of physiological responses and pathologies. Concentrations of superoxide and hydrogen peroxide in the mitochondrial matrix are set mainly by rates of production, the activities of superoxide dismutase-2 (SOD2) and peroxiredoxin-3 (PRDX3), and by diffusion of hydrogen peroxide to the cytosol. These considerations can be used to generate criteria for assessing whether changes in matrix superoxide or hydrogen peroxide are both necessary and sufficient to drive redox signaling and pathology: is a phenotype affected by suppressing superoxide and hydrogen peroxide production; by manipulating the levels of SOD2, PRDX3 or mitochondria-targeted catalase; and by adding mitochondria-targeted SOD/catalase mimetics or mitochondria-targeted antioxidants? Is the pathology associated with variants in SOD2 and PRDX3 genes? Filtering the large literature on mitochondrial redox signaling using these criteria highlights considerable evidence that mitochondrial superoxide and hydrogen peroxide drive physiological responses involved in cellular stress management, including apoptosis, autophagy, propagation of endoplasmic reticulum stress, cellular senescence, HIF1α signaling, and immune responses. They also affect cell proliferation, migration, differentiation, and the cell cycle. Filtering the huge literature on pathologies highlights strong experimental evidence that 30-40 pathologies may be driven by mitochondrial matrix superoxide or hydrogen peroxide. These can be grouped into overlapping and interacting categories: metabolic, cardiovascular, inflammatory, and neurological diseases; cancer; ischemia/reperfusion injury; aging and its diseases; external insults, and genetic diseases. Understanding the involvement of mitochondrial matrix superoxide and hydrogen peroxide concentrations in these diseases can facilitate the rational development of appropriate therapies.

Association of Genes Related to Oxidative Stress with the Extent of Coronary Atherosclerosis

Oxidative stress is believed to play a critical role in atherosclerosis initiation and progression. In line with this, in a group of 1099 subjects, we determined eight single nucleotide polymorphisms (SNPs) related to oxidative stress (PON1 c.575A>G, MPO c.−463G>A, SOD2 c.47T>C, GCLM c.−590C>T, NOS3 c.894G>T, NOS3 c.−786T>C, CYBA c.214C>T, and CYBA c.−932A>G) and assessed the extent of atherosclerosis in coronary arteries based on Gensini score. An increased risk of having a Gensini score in the higher half of the distribution was observed for the PON1 c.575G allele (odds ratio (OR) = 1.27, 95% confidence interval (CI): 1.004–1.617, p = 0.046). Next, the genetic risk score (GRS) for the additive effect of the total number of pro-oxidative alleles was assessed. We noted an increase in the risk of having a Gensini score above the median with the maximum number of risk alleles (OR = 2.47, 95% CI: 1.19–5.23, p = 0.014). A univariate Spearman’s test revealed significant correlation between the total number of pro-oxidant alleles (GRS) and the Gensini score (ρ = 0.068, p = 0.03). In conclusion, the PON1 c.575A>G variant and the high number of risk alleles (GRS) were independent risk factors for a high Gensini score. We suggest, however, that GRS might occur as a more valuable component in adding a predictive value to the genetic background of atherosclerosis.

Bone morphogenetic protein 9, and its genetic variants contribute to susceptibility of idiopathic pulmonary arterial hypertension

Considering the predominant role of rare variants of the Bone morphogenetic protein 9 (BMP9) gene in the occurrence of idiopathic pulmonary arterial hypertension (IPAH), here we conducted a case-control study, together with functional validation, to explore the relationships between variants of the BMP9 gene and development of IPAH. We found minor alleles of rs3740297 (OR: 0.72, 95% CI: 0.59-0.87, P=7.77×10-5) and rs7923671 (OR: 0.76, 95% CI: 0.62-0.93, P=0.009) were significantly associated with decreased risk of IPAH. Minor alleles of rs3740297 and rs7923671 were significantly associated with increased plasma level of BMP9 in both IPAH cases and controls (P<0.001). An allele of rs7923671 showed higher relative luciferase activity compared to that containing G allele (P<0.001). Mechanism exploration found that pulmonary artery smooth muscle cells (PASMC) cell line transfected with rs3740297 C allele construct, miR-149 mimic, and antagomir miR-149 showed more sensitive change of the relative luciferase activity and BMP9 expression. This means minor allele T of rs3740297 could significantly decrease susceptibility of IPAH in Chinese population, possibly by increasing BMP9 expression through losing a miR-149 binding site. Our study provides evidence for genetic associations between two specific variants in the BMP9 gene and plasma level of BMP9, occurrence of IPAH.

SOD2 ameliorates pulmonary hypertension in a murine model of sleep apnea via suppressing expression of NLRP3 in CD11b+ cells

Background

High prevalence of obstructive sleep apnea (OSA) in the pulmonary hypertension (PH) population suggests that chronic intermittent hypoxia (CIH) is an important pathogenic factor of PH. However, the exact mechanism of CIH induced PH is not clear. One of the molecules that plays a key role in regulating pulmonary artery function under hypoxic conditions is superoxide dismutase 2 (SOD₂).

Methods

Our study utilized heterozygous SOD₂^−/+ mice firstly in CIH model to explore the exact role of SOD₂ in CIH causing PH. Expression of SOD2 was analyzed in CIH model. Echocardiography and pulmonary hypertension were measured in wild type (WT) and SOD2^−/+ mice under normal air or CIH condition. Hematoxylin–Eosin (H&E) staining and masson staining were carried out to evaluate pulmonary vascular muscularization and remodeling. Micro-PET scanning of in vivo ^99mTc-labelled- MAG3-anti-CD11b was applied to assess CD11b in quantification and localization. Level of nod-like receptor pyrin domain containing 3 (NLRP3) was analyzed by real time PCR and immunohistochemistry (IHC).

Results

Results showed that SOD₂ was down-regulated in OSA/CIH model. Deficiency of SOD2 aggravated CIH induced pulmonary hypertension and pulmonary vascular hypertrophy. CD11b⁺ cells, especially monocytic myeloid cell line-Ly6C⁺Ly6G⁻ cells, were increased in the lung, bone marrow and the blood under CIH condition, and down-regulated SOD2 activated NLRP3 in CD11b⁺ cells. SOD₂-deficient-CD11b⁺ myeloid cells promoted the apoptosis resistance and over-proliferation of human pulmonary artery smooth muscle cells (PASMCs) via up-regulating NLRP3.

Conclusion

CIH induced down-regulating of SOD2 increased pulmonary hypertension and vascular muscularization. It could be one of the mechanism of CIH leading to PH.

Oxidative Stress-Related Gene Polymorphisms Are Associated With Hepatitis B Virus-Induced Liver Disease in the Northern Chinese Han Population

Oxidative stress is closely related to the occurrence and development of various diseases such as cancer, diabetes, and cardiovascular and infectious diseases. We identified six critical genetic variants related to oxidative stress, and evaluated their main effects and their interaction effects on hepatitis B virus (HBV)-induced liver diseases. We enrolled 3,128 Han Chinese subjects into five groups: healthy controls, chronic hepatitis B (CHB), liver cirrhosis (LC), hepatocellular carcinoma (HCC), and natural clearance. We then determined the genotypes in each group for CYBA-rs4673, NCF4-rs1883112, NOX4-rs1836882, rs3017887, SOD2-rs4880, and GCLM-rs41303970, and evaluated the association between these variants and HBV-induced liver diseases. Gene-gene interactions were evaluated using generalized multifactor dimensionality reduction, logistic regression, and four-by-two tables. Significant associations were observed between healthy controls and the CIB group (CHB+LC+HCC). The CYBA-rs4673AG genotype was associated with a 1.356 rate of susceptibility of HBV-induced liver disease compared to the wild type GG genotype. The NCF4-rs1883112G allele occurred more frequently in healthy controls than in the CIB group in all three models (dominant, codominant, and recessive). Nox4-rs1836882 TC showed a protective association, being more frequent in healthy controls compared to the wild type TT genotype. GCLM-rs41303970A was associated with HBV-induced liver disease. The overall best model by multifactor dimensionality reduction was a five factor interaction model that had the highest cross validation consistency (10/10) and test accuracy (0.5669), P= 0.001. Oxidative stress-related gene polymorphisms are likely to be associated with HBV-induced liver disease, suggesting that information on these variations is useful for risk assessment of HBV-induced liver disease.

Redox Biology of Peroxisome Proliferator-Activated Receptor-γ in Pulmonary Hypertension

Significance: Peroxisome proliferator-activated receptor-gamma (PPARγ) maintains pulmonary vascular health through coordination of antioxidant defense systems, inflammation, and cellular metabolism. Insufficient PPARγ contributes to pulmonary hypertension (PH) pathogenesis, whereas therapeutic restoration of PPARγ activity attenuates PH in preclinical models. Recent Advances: Numerous studies in the past decade have elucidated the complex mechanisms by which PPARγ in the pulmonary vasculature and right ventricle (RV) protects against PH. The scope of PPARγ-interconnected pathways continues to expand and includes induction of antioxidant genes, transrepression of inflammatory signaling, regulation of mitochondrial biogenesis and bioenergetic integrity, control of cell cycle and proliferation, and regulation of vascular tone through interactions with nitric oxide and endogenous vasoactive molecules. Furthermore, PPARγ interacts with an extensive regulatory network of transcription factors and microRNAs leading to broad impact on cell signaling. Critical Issues: Abundant evidence suggests that targeting PPARγ exerts diverse salutary effects in PH and represents a novel and potentially translatable therapeutic strategy. However, progress has been slowed by an incomplete understanding of how specific PPARγ pathways are critically disrupted across PH disease subtypes and lack of optimal pharmacological ligands. Future Directions: Recent studies indicate that ligand-induced post-translational modifications of the PPARγ receptor differentially induce therapeutic benefits versus adverse side effects of PPARγ receptor activation. Strategies to selectively target PPARγ activity in diseased cells of pulmonary circulation and RV, coupled with development of ligands designed to specifically regulate post-translational PPARγ modifications, may unlock the full therapeutic potential of this versatile master transcriptional and metabolic regulator in PH.

The effect of GPx-1 rs1050450 and MnSOD rs4880 polymorphisms on PE susceptibility: a case- control study

Preeclampsia (PE) is a serious pregnancy complication whose etiology is not fully understood. However, previous reports have suggested that oxidative stress and genetic variants may contribute to the development of PE. This study aimed to examine the relationship between the Glutathione peroxidase-1(GPx-1) and Manganese Superoxide dismutase (MnSOD) polymorphisms and preeclampsia (PE) risk in Iranian women. Genotyping of the studied women, including 179 preeclamptic cases and 202 controls, for GPx-1 rs1050450 and MnSOD rs4880 polymorphisms was conducted using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Our results showed a 1.7- to 1.6-fold increased risk of PE in the rs1050450 CT and CT + TT (dominant model) genotypes compared to CC genotype (OR = 1.7, 95%CI 1.1-2.7; P = 0.01 and OR = 1.6, 95%CI 1.1-2.4; P = 0.02; respectively). We also found a marked correlation between TC and CC genotypes of MnSOD rs4880 polymorphism and a 1.9- to 2.3-fold increase risk of PE (OR = 1.9, 95%CI 1.2-2.9; P = 0.005 and OR = 2.3, 95%CI 1-5.1; P = 0.04, respectively). The rs4880 MnSOD polymorphism was correlated with increased risk of PE in the allelic and dominant models (OR = 1.8, 95% CI 1.2-2.5, P = 0.002; OR = 1.9, 95%CI 1.3-3, P = 0.002, respectively). High frequency of TC/CC genotype of MnSOD rs4880 and CT genotypes of rs1050450 polymorphism in PE patients compared to controls showed the contribution of these variants to PE susceptibility.

Association of SOD2 A16V and PON2 S311C polymorphisms with polycystic ovary syndrome in Chinese women

PURPOSE

To investigate the relationship between superoxide dismutase 2 (SOD2) A16V and paraoxonase 2 (PON2) S311C gene variants and the risk of polycystic ovary syndrome (PCOS) and evaluate the effects of the genotypes on clinical, hormonal, metabolic and oxidative stress indexes in Chinese women.

METHODS

This is a cross-sectional study of 932 patients with PCOS and 745 control women. For the clinical and metabolic association study of genotypes, 631 patients and 492 controls were included after excluding the subjects with interferential factors. Genotypes were determined by polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis. Serum total oxidant status, total antioxidant capacity (T-AOC), oxidative stress index and malondialdehyde (MDA) levels, and clinical and metabolic parameters were also analyzed.

RESULTS

The prevalence of the A allele of SOD2 A16V polymorphism was significantly greater in patients with PCOS than in control subjects. Genotype (AA + AV) remained a significant predictor for PCOS in prognostic models including age, body mass index, insulin resistance index, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides (TGs) as covariates. Patients carrying the A allele had significantly higher serum luteinizing hormone (LH) levels, and the ratio of LH to follicle-stimulating hormone compared with patients with the VV genotype. We also showed that patients carrying the C allele of the PON2 S311C polymorphism had lower T-AOC compared with patients carrying the SS genotype. However, no significant differences were observed in the frequencies of the S311C genotypes and alleles of the PON2 gene between PCOS and control groups.

CONCLUSION

The SOD2 A16V, but not PON2 S311C, polymorphism may be one of the genetic determinants for PCOS in Chinese women.

Role of Gender in Regulation of Redox Homeostasis in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is one of the diseases with a well-established gender dimorphism. The prevalence of PAH is increased in females with a ratio of 4:1, while poor survival prognosis is associated with the male gender. Nevertheless, the specific contribution of gender in disease development and progression is unclear due to the complex nature of the PAH. Oxidative and nitrosative stresses are important contributors in PAH pathogenesis; however, the role of gender in redox homeostasis has been understudied. This review is aimed to overview the possible sex-specific mechanisms responsible for the regulation of the balance between oxidants and antioxidants in relation to PAH pathobiology.

Association between Polymorphisms of Antioxidant Gene (MnSOD, CAT, and GPx1) and Risk of Coronary Artery Disease

Objective

Reactive oxygen species (ROS) been cited as one of the major causes of atherosclerosis and coronary artery disease which are possible agents inducing DNA damage. Manganese superoxide dismutase (MnSOD), catalase (CAT), and glutathione peroxidase-1 (GPx1) have evolved to address primary defense against free radical mediated damage in mitochondria. The aim of this study was to delineate the association of MnSOD, CAT, and GPx1 polymorphisms and risk of CAD in Taiwan.

Methods

We conducted a case-control study with 657 participants recruited at a medical center. All subjects were evaluated by noninvasive stress test and then quantitative coronary angiography to confirm the diagnosis of CAD. 447 CAD cases were defined as >50% stenosis of coronary artery and 210 controls were stenosed below 50%. Polymorphisms of MnSOD (Val16Ala), CAT (C-262T), and GPx1 (Pro198Leu) genes were determined by polymerase chain reaction methods. Multivariate logistic regression model was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs).

Results

The MnSOD Val/Ala+Ala/Ala genotype was significantly associated with an increased risk of CAD compared to the Val/Val genotype (OR = 1.86, 95% CI = 1.15-3.01). This polymorphism was also associated with the severity of CAD of single and two vessel diseases. The corresponding ORs were 2.31 (95% CI = 1.32-4.03) and 1.92 (95% CI = 1.02-3.61), respectively. Among cigarette smokers, the harmful genetic effect of MnSOD Ala allele on CAD risk was much higher (OR = 2.23, 95% CI = 1.02-4.88). However, the interaction between MnSOD genotype and cigarette smoking on CAD risk was not significant. No significant association between CAT and GPx1 polymorphisms and CAD risk was observed.

Conclusion

Our results suggest that MnSOD polymorphism is an independent risk factor for susceptibility to CAD in the Chinese population.

Short- and long-term gene expression profiles induced by inhaled TiO2 nanostructured aerosol in rat lung

The number of workers potentially exposed to nanoparticles (NPs) during industrial processes is increasing, although the toxicological properties of these compounds still need to be fully characterized. As NPs may be aerosolized during industrial processes, inhalation represents their main route of occupational exposure. Here, the short- and long-term pulmonary toxicological properties of titanium dioxide were studied, using conventional and molecular toxicological approaches. Fischer 344 rats were exposed to 10 mg/m³ of a TiO₂ nanostructured aerosol (NSA) by nose-only inhalation for 6 h/day, 5 days/week for 4 weeks. Lung samples were collected up to 180 post-exposure days. Biochemical and cytological analyses of bronchoalveolar lavage (BAL) showed a strong inflammatory response up to 3 post-exposure days, which decreased overtime. In addition, gene expression profiling revealed overexpression of genes involved in inflammation that was maintained 6 months after the end of exposure (long-term response). Genes involved in oxidative stress and vascular changes were also up-regulated. Long-term response was characterized by persistent altered expression of a number of genes up to 180 post-exposure days, despite the absence of significant histopathological changes. The physiopathological consequences of these changes are not fully understood, but they should raise concerns about the long-term pulmonary effects of inhaled biopersistent NPs such as TiO₂.

Reactive Oxygen and Nitrogen Species in the Development of Pulmonary Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease of the lung vasculature that involves the loss of endothelial function together with inappropriate smooth muscle cell growth, inflammation, and fibrosis. These changes underlie a progressive remodeling of blood vessels that alters flow and increases pulmonary blood pressure. Elevated pressures in the pulmonary artery imparts a chronic stress on the right ventricle which undergoes compensatory hypertrophy but eventually fails. How PAH develops remains incompletely understood and evidence for the altered production of reactive oxygen and nitrogen species (ROS, RNS respectively) in the pulmonary circulation has been well documented. There are many different types of ROS and RNS, multiple sources, and collective actions and interactions. This review summarizes past and current knowledge of the sources of ROS and RNS and how they may contribute to the loss of endothelial function and changes in smooth muscle proliferation in the pulmonary circulation.