Polymorphisms in the Mn-SOD and EC-SOD genes and their relationship to diabetic neuropathy in type 1 diabetes mellitus

Redefining distal symmetrical polyneuropathy features in type 1 diabetes: a systematic review

Diabetic neuropathy is among the most frequent complications of both type 1 (T1DM) and type 2 diabetes (T2DM) and commonly manifests as a distal symmetrical polyneuropathy (DSPN). Despite evidence that T1DM- and T2DM-related DSPN are separate entities, most of our knowledge on diabetic DSPN derives from studies focused on type 2 diabetes. This systematic review provides an overview of current evidence on DSPN in T1DM, including its epidemiological, pathophysiological and clinical features, along with principal diagnostic tests findings. This review included 182 clinical and preclinical studies. The results indicate that DSPN is a less frequent complication in T1DM compared with T2DM and that distinctive pathophysiological mechanisms underlie T1DM-related DSPN development, with hyperglycemia as a major determinant. T1DM-related DSPN more frequently manifests with non-painful than painful symptoms, with lower neuropathic pain prevalence compared with T2DM-associated DSPN. The overt clinical picture seems characterized by a higher prevalence of large fiber-related clinical signs (e.g., ankle reflexes reduction and vibration hypoesthesia) and to a lesser extent small fiber damage (e.g., thermal or pinprick hypoesthesia). These findings as a whole suggest that large fibers impairment plays a dominant role in the clinical picture of symptomatic T1DM-related DSPN. Nevertheless, small fiber diagnostic testing shows high diagnostic accuracy in detecting early nerve damage and may be an appropriate diagnostic tool for disease monitoring and screening.

Concentration/activity of superoxide dismutase isozymes and the pro-/antioxidative status, in context of type 2 diabetes and selected single nucleotide polymorphisms (genes: INS, SOD1, SOD2, SOD3) - Preliminary findings

The alterations in concentration/activity of superoxide dismutase isozymes in the context of type 2 diabetes or obesity are well-described. Moreover, many hereditary factors, including single-nucleotide polymorphisms (SNPs) of genes for coding insulin, insulin receptors, or insulin receptor substrates (INS, INSR, IRS1, IRS2) or superoxide dismutase isozymes (SOD1, SOD2, SOD3), have been linked with the incidence of obesity and diabetes. However, the underlying changes in the plasma concentration/activity of superoxide dismutase isozymes and their potential connection with the said hereditary factors remain unexplored. Previously, we have observed that the plasma concentration/activity of superoxide dismutase isozymes differs in the context of obesity and/or rs2234694 (SOD1) and rs4880 (SOD2) and that the concentrations of SOD1, SOD2, SOD3 are correlated with each other. Intersexual variability of SOD1 concentration was detected regardless of obesity. In this study, the variability of concentration/activity of superoxide dismutase isozymes in plasma is considered in the context of type 2 diabetes and/or SNPs: rs2234694 (SOD1), rs5746105 (SOD2), rs4880 (SOD2), rs927450 (SOD2), rs8192287 (SOD3). Genotypic variability of SNP rs3842729 (INS), previously studied in the context of insulin-dependent diabetes, is investigated in terms of selected clinical parameters associated with type 2 diabetes. This study revealed higher SOD1 concentration in diabetic men compared to women, and extremely high SOD1 concentration, higher total superoxide dismutase, and copper-zinc superoxide dismutase activity, and lower superoxide dismutase and copper-zinc superoxide dismutase activity (when adjusted for the concentration of SODs) in the diabetic group regardless of sex. Multiple logistic regression, applied to explore possible links between the studied SNPs and other factors with the odds of type 2 diabetes or obesity, revealed that the genotypic variability of rs4880 (SOD2) could affect these odds, supporting the findings of several other studies.

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.

Interaction of antioxidant gene variants and susceptibility to type 2 diabetes mellitus

Background: Diabetes is the seventh most common disease leading to death with a global estimate of 425 million diabetics, expected to be 629 million in 2045. The role of reactive metabolites and antioxidants, such as glutathione, glutathione peroxidase, superoxide dismutase and catalase in type 2 diabetes mellitus (T2DM) provides an opportunity for identifying gene variants and risk genotypes. We hypothesised that certain antioxidant gene-gene interactions are linked with T2DM and can model disease risk prediction.Materials and methods: Genotyping of single nucleotide polymorphisms (SNPs) in antioxidant genes for glutathione (GST), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) was performed in 558 T2DMs and 410 age and sex matched healthy controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), routine lab indices by standard techniques.Results: The null/null allele combination of GSTM1del and GSTT1del increased disease risk up to 1.7-fold. The combination of SNPs in GSTM1del, GSTT1del, GSTP1 + 313A/G and in CAT-21A/T, SOD2 + 47C/T, GPx1 + 599C/T increased the risk of diabetes 13.5 and 2.1-fold, respectively. Interaction of SNPs GSTM1del, GSTT1del, GSTP1 + 313A/G (105Ile/Val), CAT-21A/T, SOD2 + 47C/T, GPx1 + 599C/T were significantly linked with disease risk >5 × 10³ fold.Conclusion: As the number of gene combinations increase, there is a rise in the odds ratio of disease risk, suggesting that gene-gene interaction plays an important role in T2DM susceptibility. Individuals who possess the GSTM1del, GSTT1del, GSTP1 105I/V(+313A/G), CAT-21A/T, SOD2 + 47C/T and GPx1 + 599C/T are at very high risk of developing T2DM.

The relationship between MnSOD Val16Ala gene polymorphism and the level of serum total antioxidant capacity with the risk of chronic kidney disease in type 2 diabetic patients: a nested case-control study in the Tehran lipid glucose study

Background

Several studies have shown significant associations between manganese superoxide dismutase (MnSOD) Val16Ala polymorphism and diabetic complications, but this association has not been explored in relation with chronic kidney disease (CKD) in Type 2 diabetes mellitus (T2DM) patients. Total antioxidant capacity (TAC) level changes in diabetic condition and may play important role in onset or progression of the disease and its complications. The present study investigated the association of MnSOD Val16Ala polymorphism and serum TAC with the risk of CKD in T2DM patients.

Methods

This nested case-control study included 280 type 2 diabetic patients with CKD and 280 age, sex and diabetes duration-matched control subjects selected from the participants of the Tehran Lipid and Glucose Study. MnSOD val16Ala (rs4880) SNP was genotyped by the Tetra-Primer ARMS-polymerase chain reaction analysis. Serum TAC was measured using ferric-reducing antioxidant power assay. Statistical analysis was performed using STATA statistical package v.12.0 or SPSS (Version 22.0).

Results

The Ala allele of the MnSOD Val16Ala polymorphism was associated with a lower risk of CKD (odds ratio (OR), 0.55; 95% confidence interval (CI), 0.36–0.84; P = 0.006). Median serum TAC in CKD group was 920 μmol/L and was significantly lower (p < 0.001) compared to the control group (1045 μmol/L). Using an adjusted conditional logistic regression, we didn’t observe any significant interaction between MnSOD Val16Ala SNP with quartiles of serum TAC in relation to CKD.

Conclusion

A significant association was found between the MnSOD Val16Ala polymorphism and CKD, but this association is not affected by serum TAC level in T2DM patients.

Superoxide Dismutase 1 and 2 Gene Polymorphism in Turkish Vitiligo Patients

Vitiligo is an acquired disease of unknown etiology. Several theories have been proposed to understand the pathogenesis. The role of oxidative stress has been getting more important in recent years. One of the primary antioxidant enzymes in vitiligo is the superoxide dismutase (SOD). The aim of this study is to investigate the polymorphisms of the SOD1 and SOD2 in Turkish vitiligo patients. One hundred one vitiligo patients and 99 healthy controls without family history of vitiligo were included into the study. The SOD1 35 A/C and SOD2 A16V (C/T) polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphim (PCR-RFLP). Vitiligo patients and control group of SOD1 35 A/C and SOD2 A16V (C/T) polymorphism allele frequencies were compared by using χ² tests. The distribution of the SOD1 35 AA and AC genotypes were similar in vitiligo patients and control group. When the patient and the control groups were compared for the SOD2 Ala9Val (C/T) polymorphism, a significant difference was determined for the distribution of the genotypes [p = 0.047, odds ratio (OR) = 2.075, 95% confidence interval (95% CI) = 1.008-4.272]. The relative risk for development of vitiligo was found as a 2-fold increase in the TT genotype. The increase of TT homozygosity in the vitiligo cases creates the problem on the transfer of the enzyme to the mitochondria and thus, the SODs antioxidant effect may decrease in vitiligo but the polymorphism was not determined in all patients, so this study needs to be substantiated by other studies containing a higher number of patients.

Human Nutrition and Genetic Variation

Human genetic variation is a determinant of nutrient efficacy and of tolerances and intolerances and has the potential to influence nutrient intake values (NIVs). Knowledge derived from the comprehensive identification of human genetic variation offers the potential to predict the physiological and pathological consequences of individual genetic differences and prevent and/or manage adverse outcomes through diet. Nutrients and genomes interact reciprocally; genomes confer differences in nutrient utilization, whereas nutrients effectively modify genome expression, stability, and viability. Understanding the interactions that occur among human genes, including all genetic variants thereof, and environmental exposures is enabling the development of genotype-specific nutritional regimens that prevent disease and promote wellness for individuals and populations throughout the life cycle. Genomic technologies may provide new criteria for establishing NIVs. The impact of a gene variant on NIVs will be dependent on its penetrance and prevalence within a population. Recent experiences indicate that few gene variants are anticipated to be sufficiently penetrant to affect average requirement (AR) values to a greater degree than environmental factors. If highly penetrant gene variants are identified that affect nutrient requirements, the prevalence of the variant in that country or region will determine the feasibility and necessity of deriving more than one AR or upper limit (UL) for affected genetic subgroups.

Role of Superoxide Dismutase 2 Gene Ala16Val Polymorphism and Total Antioxidant Capacity in Diabetes and its Complications

Diabetes Mellitus (DM) is a chronic heterogeneous disorder and oxidative stress is a key participant in the development and progression of it and its complications. Anti-oxidant status can affect vulnerability to oxidative damage, onset and progression of diabetes and diabetes complications. Superoxide dismutase 2 (SOD2) is one of the major antioxidant defense systems against free radicals. SOD2 is encoded by the nuclear SOD2 gene located on the human chromosome 6q25 and the Ala16Val polymorphism has been identified in exon 2 of the human SOD2 gene. Ala16Val (rs4880) is the most commonly studied SOD2 single nucleotide polymorphism (SNP) in SOD2 gene. This SNP changes the amino acid at position 16 from valine (Val) to alanine (Ala), which has been shown to cause a conformational change in the target sequence of manganese superoxide dismutase (MnSOD) and also affects MnSOD activity in mitochondria. Ala16Val SNP and changes in the activity of the SOD2 antioxidant enzyme have been associated with altered progression and risk of different diseases. Association of this SNP with diabetes and some of its complications have been studied in numerous studies. This review evaluated how rs4880, oxidative stress and antioxidant status are associated with diabetes and its complications although some aspects of this line still remain unclear.

Association investigation of BACH2 rs3757247 and SOD2 rs4880 polymorphisms with the type 1 diabetes and diabetes long-term complications risk in the Polish population

Genetic factors are indicated in the development of type 1 diabetes (DM1). Recently, nucleotide variants of BACH2 and SOD2 have been associated with this chronic condition. Therefore, the purpose of the present study was to investigate the contribution of BACH2 rs3757247 and SOD2 rs4880 (Ala16Val) polymorphisms to the risk of DM1 and diabetes long-term complications. Selected polymorphic variants of BACH2 and SOD2 were investigated in a group of 141 patients with DM1 and in a group of age, gender-matched healthy subjects (n=369) using a high-resolution melting curve method. There was no evidence for either allelic or genotypic association with the risk of DM1 and diabetes chronic complications for analysed polymorphisms. In addition, no interaction between BACH2 and SOD2 variants in the development of this condition was observed. However, the frequency of BACH2 rs3757247 AG and AA genotypes was statistically different between DM1 patients with retinopathy and healthy individuals (odds ratio, 2.455; 95% confidence interval, 0.999-6.035; P=0.044), but this result did not survive multiple testing corrections. The present study did not confirm the involvement of BACH2 rs3757247 and SOD2 rs4880 polymorphisms in the development of DM1 and diabetes long-term complications. Further studies in a larger population sample are required.

Association of Superoxide dismutases (SOD1 and SOD2) and Glutathione peroxidase 1 (GPx1) gene polymorphisms with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a metabolic disorder resulting from oxidative stress (OS), the root cause of insulin resistance, β-cell dysfunction, and impaired glucose tolerance. Antioxidant enzymes play key roles in cellular defense and can be used as important biomarkers for T2DM. The present study was undertaken to evaluate three genetic polymorphisms viz. SOD1 + 35A/C, SOD2 + 47C/T, and GPx + 599C/T in 207 T2DM cases and 210 healthy controls from North India. DNA was extracted from blood samples and genotyping was done by PCR-RFLP. Genotypic/allelic frequencies and haplotype/gene-gene interaction analysis were performed using SPSS (version 15.0) and SHEsis (v. online). Except age, all other biochemical parameters showed highly significant association in T2DM cases (P < 0.001). In North Indian population, SOD1 + 35A/C variant was monomorphic. Genotype/allele frequencies of SOD2 + 47C/T polymorphism and carriage rate of 'C' allele showed significant association (p < 0.05, < 0.001; OR 2.434). Genotype/allele frequencies of GPx1 + 599C/T and carriage rate showed no association although the odds ratio of GPx1 'C' allele indicated a 1.362 times higher risk of T2DM. SOD2 'CT' and GPx1 'CC' genotypes showed maximum association with biochemical parameters. Haplotype/gene-gene interaction analysis in controls and cases showed that SOD2 + 47C/T and GPx1 + 599C/T were in linkage disequilibrium (D: 0.168; r(2): 0.10) and individuals with this combination had a 1.273 times higher risk [OR; CI (95%)] of developing T2DM. Thus, we conclude that it is essential to assess the combinatorial association of gene variants with T2DM in order to identify risk haplotypes in a population.

Association of RAGE (p.Gly82Ser) and MnSOD (p.Val16Ala) polymorphisms with diabetic retinopathy in T2DM patients from north India

AIMS

The present study aimed to examine the association of RAGE (p.Gly82Ser) and MnSOD (p.Val16Ala) polymorphisms with diabetic retinopathy (DR) in north Indian T2DM patients.

METHODS

In this case-control association study, 758 T2DM patients were recruited. 446 with retinal neovascularization, microneurysms and hemorrhages were considered as cases (DR) and 312 patients with T2DM and no clinical signs of retinopathy (DNR), were recruited as controls. Genotypes for RAGE (p.Gly82Ser) and MnSOD (p.Val16Ala) polymorphisms were generated by direct sequencing of amplified products.

RESULTS

Genotype distribution of p.Gly82Ser (RAGE) and p.Val16Ala (MnSOD) polymorphisms were significantly different between DR and DNR (p<0.05) whereas distribution of allele frequency did not differ significantly (p>0.05). A significantly higher frequency of homozygous Ser82 genotype in DR patients was detected compared with DNR (2.4% vs 0.64%) for p.Gly82Ser (RAGE) polymorphism whereas there was a higher frequency of homozygous Ala16 genotype for p.Val16Ala (MnSOD) polymorphism in DR patients compared with DNR (22.6% vs 19.3%). Binary logistic analyses showed an association of homozygous recessive genotype Ser82 with DR (OR: 2.63%, 95% CI: 0.16-15.88, p<0.033) for p.Gly82Ser (RAGE) polymorphism. However, we did not find a significant association of p.Val16Ala polymorphism in MnSOD with retinopathy.

CONCLUSIONS

The findings indicate a statistically significant association of p.Gly82Ser polymorphism in RAGE with DR in T2DM patients.

Polymorphic differences in SOD-2 may influence HCV viral clearance

Hepatitis C virus (HCV) is a pathogen causing chronic hepatitis, cirrhosis, and liver cancer occurring in about 3% of the world's population. Most individuals infected with HCV develop persistent viremia. Oxidative stress may play an important role in the pathogenesis of a number of diseases including HCV infection and diabetes mellitus. Polymorphisms in the antioxidant genes may determine cellular oxidative stress levels as a primary pathogenic role in HCV and/or in its complications. Patients with HCV and normal, healthy controls were investigated for a superoxide dismutase (SOD-2) polymorphism in the mitochondrial targeting sequence with Ala/Val (C-9T) substitution. Polymorphisms in antioxidant gene SOD-2 were carried out by PCR, restriction fragment length polymorphism assays and by polyacrylamide gel electrophoresis. For the SOD-2 polymorphism, the RNA positive group showed a higher percentage of "CT" genotype than the RNA negative group (89.3% vs. 66.1%, P = 0.001, χ(2)  = 11.9). The RNA negative group had more TT genotypes than the RNA positive group (27.4% vs. 6.80%, P = 0.01, χ(2)  = 11.6). The exposed uninfected group had an increased frequency of the "CT" genotype (86.2% vs. 66.1%, P = 0.02, χ(2)  = 5.5). The RNA positives had a higher frequency of the "CT" from the normal controls (72.1% vs. 89.2%, P = 0.005, χ(2)  = 7.8).

Association of the C47T polymorphism in SOD2 with diabetes mellitus and diabetic microvascular complications: a meta-analysis

AIMS/HYPOTHESIS

A meta-analysis was performed to assess the association of C47T (rs4880) (also called Val16Ala) polymorphism in SOD2 gene with reduced risk of diabetes mellitus, including type 1 and type 2 diabetes, and diabetic microvascular complications (DMI) including diabetic nephropathy, diabetic retinopathy and diabetic polyneuropathy.

METHODS

A comprehensive search was conducted to identify all case-control or cohort design studies of the above-mentioned associations. The fixed or random effect pooled measure was selected on the basis of homogeneity test among studies. Heterogeneity among studies was evaluated using the I (2). Meta-regression and the 'leave one out' sensitive analysis of Patsopoulos et al. were used to explore potential sources of between-study heterogeneity. Publication bias was estimated using modified Egger's linear regression test as proposed by Harbord et al.

RESULTS

Seventeen articles were included. After excluding articles that deviated from Hardy-Weinberg equilibrium in cases and/or in controls, and were also the key contributors to between-study heterogeneity, the meta-analysis showed a significant association of the C allele with reduced risk of DMI in dominant (OR 0.788, 95% CI 0.680-0.914), recessive (OR 0.808, 95% CI 0.685-0.953) and codominant (OR 0.828, 95% CI 0.751-0.913) models. It also showed a significant association with reduced risk of diabetic nephropathy in the dominant model (OR 0.801, 95% CI 0.664-0.967), and reduced risk of diabetic retinopathy in the dominant (OR 0.601, 95% CI 0.423-0.855), recessive (OR 0.548, 95% CI 0.369-0.814) and codominant (OR 0.651, 95% CI 0.517-0.820) models.

CONCLUSIONS/INTERPRETATION

The meta-analysis suggested that C allele of C47T polymorphism in SOD2 gene has protective effects on risk of DMI, diabetic nephropathy and diabetic retinopathy. This risk needs to be confirmed by further studies.

Association between the rs4880 superoxide dismutase 2 (C>T) gene variant and coronary heart disease in diabetes mellitus

Mitochondrial superoxide dismutase 2 (SOD2) is an endogenous anti-oxidant enzyme. The rs4880 gene variant results in a C>T substitution, influencing SOD enzymatic activity. This variant has been associated with micro- and macro-vascular complications in diabetes mellitus. Our aim was to examine the association between this variant and coronary heart disease (CHD) risk in a cross-sectional sample of subjects with diabetes. 776 Caucasian subjects with diabetes were genotyped. CHD risk, oxidised-LDL and plasma total anti-oxidant status (TAOS) were analysed in relation to genotype. In females, the TT genotype was associated with CHD (CC/CT/TT: No CHD vs. CHD: 22.4/56.0/21.6% vs. 12.0/50.0/38.0%, p=0.03; for CC/CT vs. TT, p=0.01). The odds ratio for CHD associated with the TT genotype compared to CC/CT was 2.22 [95%CI: 1.17-4.24], p=0.01. The TT genotype was also associated with significantly lower plasma TAOS. In males, no association was observed between genotype and CHD risk, but CHD was significantly associated with age, lower HDL, higher triglycerides, higher BMI and cigarette smoking. The TT genotype of this variant is associated with increased CHD risk and lower plasma anti-oxidant defences in females with diabetes. This modest genotype-effect is not apparent in males where traditional risk factors may play a greater role.

A novel Real Time PCR strategy to detect SOD3 SNP using LNA probes

Extracellular superoxide dismutase (SOD3) is the primary enzymatic antioxidant defence of the vascular wall. The physiopathological role of SOD3 has been examined in vascular-related diseases, atherosclerosis, hypertension, diabetes, ischaemia-reperfusion injury, lung disease, various inflammatory conditions, and neurological diseases. An important single nucleotide polymorphism (SNP), nt.760 G>C of the SOD3 gene (rs#1799895) leads to the amino acid substitution Arg(213)Gly (R213G) in the center of the heparin-binding domain and consequently to a lowered affinity for the endothelium. This mutation, which occurs with a relatively high frequency in the population (4% of Swedish, 3% of Australian and 6% of Japanese people), is associated with decreased tissue antioxidant defences and increased risk of ischaemic heart disease. The identification of patients carrying this mutation is therefore of great interest in order to highlight lowered antioxidant defences at a vascular level which could lead to increased susceptibility toward coronary artery disease and atherogenesis. Here we describe a method to detect the 760 G>C single nucleotide polymorphism based on Real Time PCR strategy using locked nucleic acid (LNA) probes. This technique, a modification of classic TaqMan probes SNP genotyping, amplifies and detects the mutation in a single reaction tube. Moreover, the implementation of LNA probes remarkably increases the specificity of the reaction. The proposed method enables unambigous and rapid discrimination of wild type and mutant genotype both in plasmid and genomic DNA samples. In light of the role of SOD3 polymorphism, the genotyping of 760 G>C mutant has important clinical implications. The proposed assay combines rapidity, high specificity, can be easily automated and overall reduces labor and cost of analyses. Moreover, identification of patients with lowered vascular antioxidant defences could address pharmacogenomical approaches to the therapy of cardiovascular diseases.

Oxidative stress pathway genes and chronic renal insufficiency in Asian Indians with Type 2 diabetes

BACKGROUND

There are significant regional variations in prevalence of diabetes and diabetic chronic renal insufficiency (CRI) in India. Oxidative stress plays an important role in the development of diabetic complications. To determine the importance of the polymorphisms in the genes involved in maintenance of cellular redox balance, we performed a case control study in subjects from south and north India.

METHODS

Successive cases presenting to the study centers with Type 2 diabetes of >2 years duration and moderate CRI (n=194, south India 104, north India 90) diagnosed by serum creatinine >or=2 mg/dl after exclusion of nondiabetic causes of CRI were compared with diabetes subjects with no evidence of renal disease (n=224, south India 149, north India 75). Twenty-six polymorphisms from 13 genes from the oxidative stress pathway were analyzed using polymerase chain reaction-restriction fragment length polymorphism. Genes included were superoxide dismutases (SOD1, 2, 3), uncoupling proteins (UCP1, 2), endothelial nitric oxide synthase (NOS3), glutathione-S-transferases (GST) (M1, T1, P1), vascular endothelial growth factor (VEGF), paraoxonase (PON) 1 and 2, and nicotinamide adenine dinucleotide phosphate reduced, oxidase p22(phox). Genes were tested for their association with CRI using chi(2) test.

RESULTS

In south Indian (SI) subjects there was significant allelic and genotypic association of the wild-type allele in SOD2 (Ala9Val; P=.002 and P=.013, respectively), UCP1 (-112 T>G, P=.012 and P=.009; Ala64Thr, P=.015 and P=.004), NOS3 (Glu298Asp, P=.002 and P=.009) and GSTP1 (Ile105Val, P=.003 and P=.004) genes with development of CRI. None of these observations were replicated in the north Indian (NI) subjects. A genotypic but not allelic association was observed for two markers, VEGF (-460 T>C) and PON1 (Arg192Gly) among NI diabetic CRI subjects.

CONCLUSION

The nonreplication of association suggests differential genetic susceptibility of the two populations to diabetic chronic renal insufficiency. In the SI diabetic subjects, oxidative stress pathway genes might be an important predictor for the development of diabetic complications. Further, the association of wild-type alleles may suggest that they confer greater survival ability to comorbid complications and may be nephroprotective.

Manganese superoxide dismutase gene polymorphism, MnSOD plasma levels and risk of epithelial ovarian cancer

AIM

We aimed to confirm any relation between the manganese-containing superoxide dismutase (MnSOD) polymorphism and risk of ovarian carcinoma as well as to demonstrate any relation between the MnSOD mitochondrial signal sequence polymorphism and plasma MnSOD enzyme levels in women with ovarian carcinoma and healthy subjects.

METHODS

In a population-based case - control study, we compared 55 cases with ovarian carcinoma and 51 controls regarding the occurrence of the C/T (alanine/valine, A/V) substitution at the -9 position in the mitochondrial signal sequence of the MnSOD gene. Polymerase chain reaction, restriction fragment length polymorphism and Nu-Sieve agarose gel electrophoresis were utilized to perform genotyping. Additionally, MnSOD plasma levels were measured using enzyme-linked immunosorbent assay methodology.

RESULTS

There were no statistically significant elevated risks associated with V or A alleles. No statistically significant association between the alleles and plasma MnSOD levels were found. Overall plasma MnSOD levels were found to be significantly higher in the patient group.

CONCLUSIONS

Although in this study, patients with ovarian carcinoma had significantly higher plasma MnSOD levels than the control group (P<0.001), no influence of the allelic distribution on plasma MnSOD levels could be detected in either group. Our results are in disagreement with earlier findings that there was an association between the A allele and increased risk for ovarian carcinoma. Thus, an extended study for a possible association between the MnSOD diallelic polymorphism and risk of ovarian cancer may be warranted.

Manganese superoxide dismutase gene coding region polymorphisms lack clinical incidence in general population

Two functional polymorphisms within the manganese superoxide dismutase (MnSOD) gene have been reported to lead to increased oxidative stress damage. The MnSOD 58T > C single nucleotide polymorphism (SNP) within exon 3 changes isoleucine to threonine, leading to decreased thermal stability and reduced enzymatic activity in vivo and in vitro. The MnSOD 60C > T polymorphism within exon 3 changes leucine to phenylalanine, rendering the protein sensitive to redox regulation by intracellular thiols. Thus, the goal of this study was to evaluate the 58T > C and 60C > T MnSOD polymorphisms in a large case-control study. Taqman allelic discrimination assays were developed to identify the 58T > C and 60C > T SNPs in exon 3. Two hundred and eight lung cancer cases and 141 controls were evaluated for these two SNPs, and all 349 subjects were of the wild-type homozygous genotype for both 58C and 60T in exon 3. This study suggests that although the 58T > C and 60C > T polymorphisms reduce MnSOD enzymatic activity, these polymorphisms were not identified in the present case-control study population.

Gene polymorphisms of superoxide dismutases and catalase in diabetes mellitus

Background

Reactive oxygen species generated by hyperglycaemia modify structure and function of lipids, proteins and other molecules taking part in chronic vascular changes in diabetes mellitus (DM). Low activity of scavenger enzymes has been observed in patients with DM. Protective role of scavenger enzymes may be deteriorated by oxidative stress. This study was undertaken to investigate the association between gene polymorphisms of selected antioxidant enzymes and vascular complications of DM.

Results

Significant differences in allele and genotype distribution among T1DM, T2DM and control persons were found in SOD1 and SOD2 genes but not in CAT gene (p < 0,01). Serum SOD activity was significantly decreased in T1DM and T2DM subjects compared to the control subjects (p < 0,05). SOD1 and SOD2 polymorphisms may affect SOD activity. Serum SOD activity was higher in CC than in TT genotype of SOD2 gene (p < 0,05) and higher in AA than in CC genotype of SOD1 gene (p < 0,05). Better diabetes control was found in patients with CC than with TT genotype of SOD2 gene. Significantly different allele and genotype frequencies of SOD2 gene polymorphism were found among diabetic patients with macroangiopathy and those without it. No difference was associated with microangiopathy in all studied genes.

Conclusion

The results of our study demonstrate that oxidative stress in DM can be accelerated not only due to increased production of ROS caused by hyperglycaemia but also by reduced ability of antioxidant defense system caused at least partly by SNPs of some scavenger enzymes.

Polymorphism in the manganese superoxide dismutase gene

Oxidative stress and mitochondrial damage occur in sepsis. Manganese superoxide dismutase (MnSOD) provides the main defence against oxidative stress within mitochondria. Ala9Val is a single nucleotide polymorphism (SNP) in the MnSOD gene, predicted to affect intra-mitochondrial transport of the enzyme. We found a significant difference in the genotype frequency between healthy subjects (n = 100) and patients with sepsis (n = 40, p = 0.009). For assessment of functionality ten healthy subjects of each homozygous genotype (A/A or V/V) were studied. Peripheral blood mononuclear cells were separated and incubated for 18 h with lipopolysaccharide (LPS), followed by analysis of mitochondrial and cytosolic fractions. There was no difference between genotypes in MnSOD activity and cytochrome c concentration, and minor differences in total antioxidant capacity (TAC) and mitochondrial membrane potential, which did not affect response to LPS. Despite predictions from structural enzyme studies that mitochondrial trafficking would be affected by the Ala9Val polymorphism of the MnSOD gene had little functional effect.

The investigation of GSTT1, GSTM1 and SOD polymorphism in bladder cancer patients

Glutathione S transferases (GSTT1, GSTM1, GSTP1) are enzymes that activate the detoxification of endogenous and exogenous agents. The genetic polymorphism in these genes may change the response of individuals to environmental toxicants. The genetic polymorphisms of GSTT1, GSTM1, GSTP1 have been studied extensively in the determination of individual cancer risks. Some studies showed a strong relationship between polymorphism of GSTs and superoxidedismutase enzymes. Using the polymerase chain reaction (PCR) the prevalence of genetic polymorphisms of GSTT1, GSTM1 and MnSOD (Manganese Superoxide Dismurase) was investigated in 104 cases and controls to seek any association with the risk of bladder cancer. The frequency of GSTT1 +/+ polymorphism was 65% (33/51) in the cases and 79% (42/53) in the controls. The frequency of the GSTM1 +/+ polymorphism was 33% (17/51) in the cases and 58% (31/53) in the controls. The frequency of the GSTM1 null genotype was 42% (22/53) in the controls and 68% (34/51) in the patients. The frequency of the SOD AA genotype was 36% (17/51) in the cases and 33% (19/53) in the controls. There was no association between the GSTT1 and SOD polymorphism and bladder cancer incidence. The incidence of the GSTM1 null genotype was increased in bladder cancer patients compared to controls (OR = 1.755, 95% CI = 1.119-2.751).

Association of manganese superoxide dismutase gene polymorphism (V16A) with diabetic macular edema in Korean type 2 diabetic patients

This study was designed to investigate whether V16A polymorphism of the manganese superoxide dismutase (Mn-SOD) gene is associated with the development of type 2 diabetes mellitus and with progression of diabetic retinopathy (DR) and diabetic macular edema (DME). We simultaneously analyzed insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene in the 16th intron to avoid its confounding effect. A total of 192 nondiabetic subjects and 304 type 2 diabetic patients were included in the study. Diabetic retinopathy was classified as nonretinopathy, nonproliferative retinopathy, and proliferative retinopathy. Diabetic macular edema was defined as thickening of the retina and/or hard exudates within a 1-disk diameter of the center of the macula. Diabetic macular edema was further classified into focal, diffuse, and ischemic types. The A allele frequency of the Mn-SOD gene was not different between nondiabetic and type 2 diabetic subjects, between the normotensive and hypertensive groups, between the DR (-) and DR (+) groups, and among the stages of DR. In the DR (+) group, the DME (+) group had a lower A allele frequency than that of the DME (-) group. In the DME (+) group, focal, diffuse, and ischemic types were found in 8, 23, and 6 patients, respectively. The A allele frequency of each type was 0.188, 0.109, and 0.0. The D allele frequency of the angiotensin-converting enzyme gene did not differ in any of the comparisons. Clinical and laboratory parameters of the A allele carriers were not different from those of the noncarriers except for the prevalence of hypertension and DME. Hypertension, diabetic duration, and insulin therapy were related to DR. The A allele, hypertension, and insulin therapy were associated with DME. In conclusion, our results suggest that V16A polymorphism of the Mn-SOD gene is not related to the development of diabetes and progression of DR, but is associated with DME in Korean type 2 diabetic patients.

Uncoupling protein 2 promoter polymorphism -866G/A affects peripheral nerve dysfunction in Japanese type 2 diabetic patients

OBJECTIVE

To determine genetic predispositions for diabetic polyneuropathy, we investigated the relationship between the -866G/A polymorphism of uncoupling protein (UCP) 2 and neurological manifestations in 197 type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

We first examined whether UCP2 mRNA had been expressed in the dorsal root ganglion (DRG) in four Long-Evans Tokushima Otsuka rats using RT-PCR and electrophoresis. Genotyping of UCP2 promoter polymorphism -866G/A was then performed in 197 unrelated Japanese type 2 diabetic patients, who were subjected to nerve conduction, quantitative vibratory perception, head-up tilt, and heart rate variability tests, by PCR restriction fragment-length polymorphism. The relationships between UCP2 genotype and various nerve functions were analyzed by uni- and multivariable analysis.

RESULTS

Expression of UCP2 mRNA was confirmed in rat DRG. Multiple regression analysis clarified the hypothesis that the G/A + A/A genotype was significantly related to decreased motor nerve conduction velocity and impaired blood pressure maintenance on the head-up tilt test. Multiple logistic regression analysis revealed that the G/A + A/A genotypes are a significant risk factor for sensory nerve conduction slowing and orthostatic hypotension.

CONCLUSIONS

UCP2 promoter gene polymorphism -866 G/A was significantly associated with nerve conduction slowing and vasomotor sympathetic functions. These findings suggest that the higher UCP2 activity related to the A allele has an energy-depleting effect on peripheral nerve function in type 2 diabetic patients.

Manganese superoxide dismutase gene polymorphism (V16A) is associated with stages of albuminuria in Korean type 2 diabetic patients

Several single-nucleotide polymorphisms of genes related to oxidative stress have been evaluated because intracellular reactive oxygen species are associated with development of diabetes and its microvascular complications. We performed a case-control study to investigate whether V16A polymorphism of manganese superoxide dismutase (Mn-SOD) gene is related to pathogenesis of diabetes and whether the polymorphism is associated with stages of albuminuria in Korean type 2 diabetic patients. Genotype distributions were studied in 178 nondiabetic subjects and 371 type 2 diabetic patients of 3 groups with a normoalbuminuria group (Normo group, n = 244), a microalbuminuria group (Micro group, n = 86), and an overt albuminuria group (Macro group, n = 41). The albumin/creatinine ratio (ACR) was defined as a urinary albumin/creatinine ratio. V16A genotypes were determined with polymerase chain reaction-restriction fragment length polymorphism method. Between nondiabetic subjects and type 2 diabetic patients, Mn-SOD genotype distribution (VV/VA + AA, 146/32 vs 314/57) and A allele frequency (0.121 vs 0.104) were not different. Patients with nephropathy, Micro and Macro groups, had significantly lower A allele frequency, longer diabetic duration, higher prevalence of hypertension, and greater ACR than those of patients without nephropathy (P < .05). A allele was significantly less frequent with progression of nephropathy (Normo group, 0.119; Micro group, 0.073; Macro group, 0.03; P < .05). In type 2 diabetic patients, A allele carriers had significantly lower prevalence of hypertension and lesser ACR than those of A allele noncarriers (P < .01). In multivariate analysis, hypertension, duration of diabetes, serum total cholesterol level, and A allele of Mn-SOD gene were independently associated with stages of albuminuria. These results suggest that V16A polymorphism of Mn-SOD gene is not related to pathogenesis of diabetes but is associated with stages of albuminuria in Korean type 2 diabetes.

Manganese superoxide dismutase alanine to valine polymorphism and risk of neuropathy and nephropathy in Egyptian type 1 diabetic patients

Oxidative stress, characterized by a marked increase in the level of oxygen free radicals (OFR), has been implicated in the development of diabetic microangiopathic complications, such as diabetic neuropathy (DN) and nephropathy (DP). Antioxidant enzymes may protect against the rapid onset and progression of microangiopathy, by reducing the excess of OFR and peroxides. Mutations and polymorphisms in genes encoding such enzymes may therefore result in a predisposition to this disorder.

AIM

We investigated the role of genes encoding the antioxidant enzyme, mitochondrial superoxide dismutase (Mn-SOD2), in DN and DP pathogenesis in an Egyptian population. We studied Ala(-9)Val polymorphism of the Mn-SOD2 gene in type 1 diabetic patients (n = 65) with DN (n = 40) or DP (n = 45).

METHODS

We used polymerase chain reaction (PCR) assays with restriction fragment length polymorphism for rapid detection of polymorphisms. These assays involved the use of mismatch PCR primers to create restriction sites in the amplified product only in presence of the polymorphic base. The PCR product was then digested with AgeI restriction enzyme to detect Ala(-9)Val polymorphic sites.

RESULTS

The frequencies of the Ala allele (odds ratio (OR) = 0.438, 95% CI of 0.247-0.778) and the Ala/Ala genotype (OR = 0.26, 95% CI of 1.39-10.266) were significantly lower in diabetic neuropathy patients. In contrast, the frequencies of the Val allele (OR = 2.282, 95% CI of 1.286-4.05) and the homozygous Val/Val genotype (OR = 6.68, 95% CI of 0.3-0.76) were significantly higher in patients with DN than diabetics without neuropathy. Although the Val allele was more frequently detected in DP patients than diabetics without nephropathy (OR = 3.2), this difference was statistically non-significant. In conclusion, Ala(-9)Val substitution in the Mn-SOD2 gene was associated with DN in Egyptian diabetic children but not a significant factor in diabetic patients with nephropathy.

Genetic polymorphism in the manganese superoxide dismutase gene, antioxidant intake, and breast cancer risk: results from the Shanghai Breast Cancer Study

INTRODUCTION

It has been suggested that oxidative stress and mitochondrial DNA damage play important roles in breast cancer carcinogenesis. Manganese superoxide dismutase (MnSOD) is a major enzyme that is responsible for the detoxification of reactive oxygen species in the mitochondria. A T --> C substitution in the MnSOD gene results in a Val --> Ala change at the -9 position of the mitochondrial targeting sequence (Val-9Ala), which alters the protein secondary structure and thus affects transport of MnSOD into the mitochondria.

METHODS

We evaluated this genetic polymorphism in association with breast cancer risk using data from the Shanghai Breast Cancer Study, a population-based case-control study conducted in urban Shanghai from 1996 to 1998. The MnSOD Val-9Ala polymorphism was examined in 1125 breast cancer cases and 1197 age-frequency-matched control individual.

RESULTS

Breast cancer risk was slightly elevated in women with Ala/Ala genotype (odds ratio [OR] 1.3, 95% confidence interval [CI] 0.7-2.3), particularly among premenopausal women (OR 1.8, 95% CI 0.9-3.7), as compared with those with Val/Val genotype. The increased risk with the Ala/Ala genotype was stronger among premenopausal women with a higher body mass index (OR 2.5, 95% CI 0.9-7.0) and more years of menstruation (OR 2.6, 95% CI 0.8-8.0). The risk among premenopausal women was further increased twofold to threefold among those with a low intake of fruits, vegetables, vitamin supplements, selenium, or antioxidant vitamins, including carotenes and vitamins A, C, and E. However, the frequency of the Ala allele was low (14%) in the study population, and most of the ORs provided above were not statistically significant.

CONCLUSION

The present study provides some evidence that genetic polymorphism in the MnSOD gene may be associated with increased risk of breast cancer among Chinese women with high levels of oxidative stress or low intake of antioxidants. Studies with a larger sample size are needed to confirm the findings.

Aldose reductase gene polymorphisms and peripheral nerve function in patients with type 2 diabetes

OBJECTIVE

We screened the human aldose reductase (ALR) gene for DNA sequence variants in type 2 diabetic and nondiabetic subjects and investigated whether the previously reported and novel polymorphisms were associated with neurophysiologic deterioration and clinical peripheral neuropathy.

RESEARCH DESIGN AND METHODS

The study population included 85 Finnish type 2 diabetic and 126 nondiabetic subjects. The genetic analyses were performed using the PCR, single-strand conformation polymorphism, restriction fragment-length polymorphism, and automated laser fluorescence scanning analyses. A detailed neurologic examination and neurophysiologic analyses were performed at the time of diagnosis and at the 10-year examination.

RESULTS

The genetic screening identified four polymorphisms: C-106T, C-11G, A11370G, and C19739A. The C and Z-2 alleles of the C-106T polymorphism and the previously reported (CA)(n) repeat marker were more frequent in type 2 diabetic subjects than in nondiabetic subjects. At baseline, the diabetic subjects with the T allele of the C-106T polymorphism had lower sensory response amplitude values in the peroneal (P = 0.025), sural (P = 0.007), and radial (P = 0.057) nerves and, during follow-up, a greater decrease in the conduction velocity of the motor peroneal nerve than those with the C-106C genotype. No associations were found between the polymorphisms examined and clinical polyneuropathy.

CONCLUSIONS

The C-106T polymorphism of the ALR gene may contribute to an early development of neurophysiologic deterioration in type 2 diabetic patients.

PCR/RFLP-based cost-effective identification of SOD2 signal (leader) sequence polymorphism (Ala–9Val) using NgoM IV: a detailed methodological approach

BACKGROUND

Superoxide dismutases (SOD) play an important role in the protection of cells and extracellular space from the products of oxidative stress. Two allelic variants have been described for the SOD2 gene (Ile58Thr involves a C to T substitution at nucleotide residue 339 and Ala-9Val involves a T to C substitution at nucleotide residue 1183). The enzyme proteins encoded by the different alleles have been suggested to have different activity patterns.

METHODS

The SOD2 polymorphism was determined using a polymerase chain reaction (PCR) and RFLP techniques with restriction endonuclease NgoM IV.

RESULTS

The most available results were obtained from with 20 pmol primer final concentration in PCR reaction. A total of 20 pmol seems the cost-effective primer concentration with maximum quality. There were no difference between the band quality of 1-5 units of restriction endonucleases. On the other hand, short and long incubation times seem to be similar in order to obtain sharp bands on agarose gel.

CONCLUSIONS

We have extended a method of SOD2 polymorphism (Ala-9Val) in mitochondrial sequence. This method provides the ability to genotype of SOD2, and it represents a fast, reliable, cost-effective and semi-automated methodology to determine SOD2 polymorphism in order to perform large-scale population studies.

[Genetics of diabetic complications: peripheral neuropathy]

Diabetic neuropathy is a common complication of type 1 and 2 diabetes mellitus. Chronic hyperglycaemia and/or insulin deficiency in the peripheral nerve lead to metabolic and vascular disturbances, responsible for the functional alterations and the characteristic histological abnormalities observed in the nerve fibre. Recently, genetic factors have been described, suggestive of a predisposition and/or a protective effect for diabetic neuropathy in certain patients. The search for these genetic factors through the study of polymorphism of gene involved in the various metabolic and vascular pathways, is currently increasing, but with contradictory results. The main studies and data are reviewed in this Article. The identification of candidate-genes should allowed, in the future, to better identify and manage diabetic patients at-risk for peripheral neuropathy.

Increased breath biomarkers of oxidative stress in diabetes mellitus

BACKGROUND

Oxidative stress has been implicated in the major complications of diabetes mellitus, including retinopathy, nephropathy, neuropathy and accelerated coronary artery disease. There is a clinical need for a marker of oxidative stress which could potentially identify diabetic patients at increased risk for these complications. We measured oxidative age, a new breath marker of oxidative stress, in diabetic patients.

METHODS

Three groups were studied: type 1 diabetes mellitus (n=9), type 2 diabetes mellitus (n=53) and non-diabetic normals (n=39). Volatile organic compounds (VOCs) in breath were assayed by gas chromatography and mass spectroscopy to construct the breath methylated alkane contour (BMAC), a three-dimensional display of oxidative stress markers, C4-C20 alkanes and monomethylated alkanes. The collective abundance of these VOCs was reduced to a single value, the oxidative age, comprising the volume under the curve of the BMAC corrected for chronological age.

RESULTS

Oxidative age was significantly increased in type 1 diabetes (mean=0.103, S.E.M.=0.119, p<0.01) and type 2 diabetes (mean=0.103, S.E.M.=0.047, p<0.05) compared to age-matched normals (mean=-0.248, S.E.M.=0.079). No significant correlation between oxidative age and blood glucose or hemoglobin A1C was observed in either group.

CONCLUSIONS

Oxidative age, a marker of oxidative stress, was significantly increased in both type 1 and type 2 diabetes mellitus. Oxidative age merits further study as a candidate marker of risk for the complications of diabetes mellitus.

MnSOD polymorphism and breast cancer in a population-based case-control study

A polymorphism in the signal sequence (Ala-9Val) of the gene encoding the free radical-quenching manganese superoxide dismutase (MnSOD) has been reported to alter the risk for breast cancer. We evaluated this relationship in a population-based case-control study (476 breast cancer cases and 502 controls). Overall, relative risks were not significantly elevated in women with one (RR: 1.27; 95% CI: 0.91-1.77) or two (RR: 1.18; 95% CI: 0.81-1.73) Ala alleles compared to those homozygous for the wild-type Val genotype. Results do not support any overall association of the Ala-9Val MnSOD polymorphism to the development of breast cancer.

High glucose stimulates angiotensinogen gene expression via reactive oxygen species generation in rat kidney proximal tubular cells

The present studies investigated whether the effect of high glucose levels on angiotensinogen (ANG) gene expression in kidney proximal tubular cells is mediated via reactive oxygen species (ROS) generation and p38 MAPK activation. Rat immortalized renal proximal tubular cells (IRPTCs) were cultured in monolayer. Cellular ROS generation and p38 MAPK phosphorylation were assessed by lucigenin assay and Western blot analysis, respectively. The levels of immunoreactive rat ANG secreted into the media and cellular ANG mRNA were determined by a specific RIA and RT-PCR, respectively. High glucose (25 mM) evoked ROS generation and p38 MAPK phosphorylation as well as stimulated immunoreactive rat ANG secretion and ANG mRNA expression in IRPTCs. These effects of high glucose were blocked by antioxidants (taurine and tiron), inhibitors of mitochondrial electron transport chain complex I (rotenone) and II (thenoyltrifluoroacetone), an inhibitor of glycolysis-derived pyruvate transport into mitochondria (alpha-cyano-4-hydroxycinnamic acid), an uncoupler of oxidative phosphorylation (carbonyl cyanide m-chlorophenylhydrazone), a manganese superoxide dismutase mimetic, catalase, and a specific inhibitor of p38 MAPK (SB 203580), but were not affected by an inhibitor of the malate-aspartate shuttle (aminooxyacetate acid). Hydrogen peroxide (>/=10(-5) M) also stimulated p38 MAPK phosphorylation, ANG secretion, and ANG mRNA gene expression, but its stimulatory effect was blocked by catalase and SB 203580. These studies demonstrate that the stimulatory action of high glucose on ANG gene expression in IRPTCs is mediated at least in part via ROS generation and subsequent p38 MAPK activation.