Association between the adiponectin promoter rs266729 gene variant and oxidative stress in patients with diabetes mellitus.

AIMS: Low levels of adiponectin are associated with type 2 diabetes and coronary heart disease (CHD). Recent evidence also suggests that low levels of adiponectin are associated with increased oxidative stress. Our aim was to examine the association between the rs266729 promoter gene variant (-11377C > G) and plasma markers of oxidative stress in diabetes subjects. METHODS AND RESULTS: Seven hundred and sixty-seven Caucasian subjects with diabetes were successfully genotyped (CC/CG/GG). Genotype data were analysed in relation to plasma total antioxidant status (TAOS) and Oxidized-LDL (Ox-LDL). Plasma adiponectin measurements were available in 206 samples. There was a significant association between genotype and plasma TAOS (CC: 42.1 +/- 13.4% vs. CG: 42.0 +/- 12.0% vs. GG: 47.9 +/- 12.0%, P = 0.02; for CC/CG vs. GG, P = 0.006). With respect to Ox-LDL, CC subjects had 8% higher plasma Ox-LDL compared with CG/GG [CC vs. CG vs. GG: 48.5 (36.3-60.2) U/L vs. 44.8 (35.6-54.1) U/L vs. 44.9 (41.2-49.1) U/L, for CC vs. CG/GG P = 0.03]. For plasma adiponectin, GG subjects had the highest levels [CC vs. CG vs. GG: 8.18 (5.69-15.38) microg/mL vs. 7.12 (5.34-12.97) microg/mL vs. 11.84 (6.98-25.25) microg/mL, P = 0.09; for CC/CG vs. GG, P = 0.05]. CONCLUSION: This study shows an association between a promoter variant in the adiponectin gene and plasma markers of oxidative stress. In line with previous studies, this work supports an antioxidant role for adiponectin which may explain its cardioprotective effect. Further prospective study is necessary to explore the effect of this gene variant in diabetes in relation to CHD risk and oxidative stress.

The effect of WNT5B IVS3C>G on the susceptibility to type 2 diabetes in UK Caucasian subjects.

BACKGROUND AND AIMS: The wnt signaling pathway regulates adipogenesis and insulin secretion. The WNT5B gene has been reported to confer susceptibility to type 2 diabetes (T2D) in the Japanese population, and we therefore evaluated this in Caucasian subjects with respect to obesity status. METHODS AND RESULTS: Two thousand seven hundred and one Caucasian middle-aged men from the prospective Northwick Park Heart Study II (NPHSII) of whom 153 developed T2D over 15 years and 1268 Caucasian middle-aged patients with T2D (60% male) were genotyped using a TaqMan assay for the IVS3C>G variant (rs2270031) in the WNT5B gene. The frequency of the G allele was 0.026 (0.022-0.031) in controls and 0.031 (0.025-0.039) in patients with diabetes, p=0.24. In the prospective analysis, G allele carriers with BMI below 26 kg/m(2) had significantly higher T2D hazard risk [3.46 (1.34-8.96), p=0.01]. Comparing T2D cases with NPHSII controls, the G allele was associated with a significantly higher T2D odds ratio (OR) of 1.50 (1.06-2.12), p=0.02 in subjects with BMI lower than 30 kg/m(2). Increasing BMI had a smaller effect on risk in G allele carriers. The effect on risk was not explained by genotype being associated with any classical T2D risk factor. When the combined effect of this SNP and the TCF7L2 IVS3C>T SNP (rs7903146) was evaluated, a 2.07 (1.40-3.07), p<0.0001 fold higher OR was observed in carriers of both the rare alleles. CONCLUSION: Variation in WNT5B predisposes to T2D in the absence of obesity. The increase in risk conferred by the presence of both WNT5B and TCF7L2 variants strengthens the role of wnt signaling in T2D.

The effect of APOA5 and APOC3 variants on lipid parameters in European Whites, Indian Asians and Afro-Caribbeans with type 2 diabetes.

Common variants in APOA5 and APOC3 have been associated with differences in plasma triglyceride (TG) levels in healthy individuals. The aim of this study was to examine the association of APOA5 (-1131T>C, S19W) and APOC3 (-482C>T, 1100C>T) polymorphisms in patients with type 2 diabetes (T2D) of European White (EW) (n=931), Indian Asian (IA) (n=610) and Afro-Caribbean (AC) (n=167) origin, with lipid and T2D parameters. Rare allele frequencies and linkage disequilibrium differed significantly amongst ethnic groups. Compared to APOA5 -1131T and 19S homozygotes, -1131C and 19W carriers had higher TGs in all groups, but this effect was only statistically significant for the -1131C in the EWs (P=0.04) and 19W in the IAs (P<0.001). APOC3 SNPs showed no significant association with lipid levels in any ethnic group. While haplotypes carrying -1131C allele showed significant TG-raising in the EWs only, the 19W defined haplotype showed significant TG-raising in both IAs and EWs. Comparing all four SNPs in EW T2D subjects with healthy EWs (n=2579), the APOC3 1100C>T frequency was significantly higher in T2D [0.26 (0.24, 0.28)] vs. healthy EWs [0.22 (0.20, 0.23)], P=0.001. While the variable size effects of the two APOA5 SNPs on TG levels may result from ethnically different gene-gene or gene-environment interactions, APOA5 and APOC3 variants did not affect parameters of T2D. However, comparison between EWs with T2D and healthy EWs suggest APOC3 1100C>T is associated with increased risk of diabetes probably through mechanisms other than direct effects on TG.

Interaction between the uncoupling protein 2 -866G>A gene variant and cigarette smoking to increase oxidative stress in subjects with diabetes.

BACKGROUND AND AIMS: Increased oxidative stress is associated with coronary heart disease (CHD). The mitochondrial uncoupling protein-2 (UCP2) negatively regulates reactive oxygen species generation. We have observed that a common variant (-866G>A) in the promoter region of UCP2 is associated with increased CHD risk in healthy men and increased oxidative stress in diabetic men with CHD. The aim of the current study was to test the hypothesis that this variant might interact with smoking (an environmental stress) to influence plasma markers of oxidative stress. METHODS AND RESULTS: Amongst 453 Caucasian diabetic men there was a significant interaction (p=0.001) between genotype and smoking in determining plasma Total AntiOxidant Status (TAOS). Current smokers with the -866AA genotype had the lowest TAOS (indicating higher oxidative stress) of all subjects (AA vs. GG: 32.00+/-17.4% vs. 45.8+/-12.6%, p=0.04). In a sub-sample of 20 subjects (10 GG, 10 AA) matched for baseline characteristics, plasma markers of oxidative stress in current smokers were significantly higher in AA compared to GG subjects (TAOS 36.8+/-9.5% vs. 51.4+/-9.5%, p=0.04; F(2)-isoprostanes 1133.6+/-701.2 pg ml(-1) vs. 500.8+/-64.7 pg ml(-1), p=0.04). CONCLUSIONS: This study demonstrates an interaction between the UCP2 -866G>A variant and smoking to increase oxidative stress in vivo.

Mitochondrial oxidative stress, endothelial function and metabolic control in patients with type II diabetes and periodontitis: A randomised controlled clinical trial.

BACKGROUND: Periodontitis (PD) and type 2 diabetes (T2D) are characterized by increased mitochondrial oxidative stress production (mtROS), which has been associated with a greater risk of cardiovascular diseases (CVD). Intensive PD treatment (IPT) can significantly improve endothelial function and metabolic control, although the mechanisms remain unclear. We explored whether, in patients with PD and T2D, changes of mtROS are associated with improvement of endothelial function and metabolic control after IPT. METHODS: 51 patients with T2D and PD were enrolled in a single-blind controlled trial and randomised to either intensive (n = 27) or standard (CPT, n = 24) PD treatment. Levels of mtROS in peripheral blood mononuclear cells (PBMC) were measured using a FACS-based assay at baseline and 24 h, 1 week, 2 and 6 months after PD treatment. Inflammatory cytokines, CVD risk factors, metabolic control and endothelial function were assessed at baseline and 6 months after intervention. RESULTS: After 6 months from PD treatment, the IPT group had lower mtROS (in both the whole PBMC and lymphocytes), circulating levels of HbA1c, glucose, INF-γ, TNF-α (p < 0.05 for all), and improved endothelial function (p < 0.05) compared to the CPT group. There was an association between higher mtROS and lower endothelial function at baseline (r = -0.39; p = 0.01) and, in the IPT group, changes of mtROS were associated with changes of endothelial function (r = 0.41; p < 0.05). CONCLUSIONS: Reduced mtROS is associated with improved endothelial function and accompanied by better metabolic control in patients with T2D and PD. mtROS could represent a novel therapeutic target to prevent CVD in T2D.

Combined immunosuppression and radiotherapy in thyroid eye disease (CIRTED): a multicentre, 2 × 2 factorial, double-blind, randomised controlled trial.

BACKGROUND: Standard treatment for thyroid eye disease is with systemic corticosteroids. We aimed to establish whether orbital radiotherapy or antiproliferative immunosuppression would confer any additional benefit. METHODS: CIRTED was a multicentre, double-blind, randomised controlled trial with a 2 × 2 factorial design done at six centres in the UK. Adults with active moderate-to-severe thyroid eye disease associated with proptosis or ocular motility restriction were recruited to the trial. Patients all received a 24 week course of oral prednisolone (80 mg per day, reduced to 20 mg per day by 6 weeks, 10 mg per day by 15 weeks, and 5 mg per day by 21 weeks) and were randomly assigned via remote computerised randomisation to receive either radiotherapy or sham radiotherapy and azathioprine or placebo in a 2 × 2 factorial design. Randomisation included minimisation to reduce baseline disparities in potential confounding variables between trial interventions. Patients and data analysts were masked to assignment, whereas trial coordinators (who monitored blood results), pharmacists, and radiographers were not. The radiotherapy dose was 20 Gy administered to the retrobulbar orbit in ten to 12 fractions over 2 to 3 weeks. Azathioprine treatment was provided for 48 weeks at 100-200 mg per day (dispensed as 50 mg tablets), depending on bodyweight (100 mg for <50 kg, 150 mg 50-79 kg, 200 mg for ≥80 kg). The primary outcomes were a binary composite clinical outcome score and an ophthalmopathy index at 48 weeks, and a clinical activity score at 12 weeks. The primary analysis was based on the intention-to-treat allocation and safety was assessed in all participants. This study is registered with ISRCTN, number 22471573. FINDINGS: Between Feb 15, 2006, and Oct 3, 2013, 126 patients were recruited and randomly assigned to groups: 31 patients to radiotherapy plus azathioprine, 31 to sham radiotherapy and azathioprine, 32 to radiotherapy and placebo, and 32 to sham radiotherapy and placebo. Outcome data were available for 103 patients (54 for sham radiotherapy vs 49 for radiotherapy and 53 for placebo vs 50 for azathioprine), of whom 84 completed their allocated treatment of radiotherapy or sham radiotherapy and 57 continued to take azathioprine or placebo up to 48 weeks. There was no interaction betweeen azathioprine and radiotherapy (pinteraction=0·86). The adjusted odds ratio (ORadj) for improvement in the binary clinical composite outcome measure was 2·56 (95% CI 0·98-6·66, p=0·054) for azathioprine and 0·89 (0·36-2·23, p=0·80) for radiotherapy. In a post-hoc analysis of patients who completed their allocated therapy the ORadj for improvement was 6·83 (1·66-28·1, p=0·008) for azathioprine and 1·32 (0·30-4·84, p=0·67) for radiotherapy. The ophthalmopathy index, clinical activity score, and numbers of adverse events (161 with azathioprine and 156 with radiotherapy) did not differ between treatment groups. In both groups, the most common adverse events were mild infections. No patients died during the study. INTERPRETATION: In patients receiving oral prednisolone for 24 weeks, radiotherapy did not have added benefit. We also did not find added benefit for addition of azathioprine in the primary analysis; however, our conclusions are limited by the high number of patients who withdrew from treatment. Results of post-hoc analysis of those who completed the assigned treatment suggest improved clinical outcome at 48 weeks with azathioprine treatment. FUNDING: National Eye Research Centre, Above and Beyond, and Moorfields Eye Charity.

Plasma heat shock protein 60 and cardiovascular disease risk: the role of psychosocial, genetic, and biological factors.

The Whitehall Study is a prospective epidemiological study of cardiovascular risk factors in healthy members of the British Civil Service, which has identified psychological distress as a major risk factor for coronary heart disease. The levels of circulating Hsp60 in 860 participants from the Whitehall cohort and 761 individuals diagnosed with diabetes have been measured and related to psychological, biological, and genetic factors. In the Whitehall participants, concentrations of Hsp60 ranged from undetectable to mg/mL levels. Circulating Hsp60 correlated with total and low-density lipoprotein (LDL) cholesterol and was positively associated with a flattened slope of cortisol decline over the day. Levels of this stress protein also correlated with measures of psychological stress including psychological distress, job demand, and low emotional support. Mass spectrometric analysis of circulating immunoreactive Hsp60 reveal that it is predominantly the intact protein with no mitochondrial import peptide, suggesting that this circulating protein emanates from mitochondria. The Hsp60 is stable when added to plasma and the levels in the circulation of individuals are remarkably constant over a 4-year period, suggesting plasma levels are partly genetically controlled. Sequence analysis of the HSP60-HSP10 intergenic promoter region identified a common variant 3175 C>G where the G allele had a frequency of 0.30 and was associated with higher Hsp60 levels in 761 type 2 diabetic patients. The extended range of plasma Hsp60 concentrations in the general population is genuine and is likely to be related to genetic, biological, and psychosocial risk factors for coronary artery disease.

Common variants in the TCF7L2 gene and predisposition to type 2 diabetes in UK European Whites, Indian Asians and Afro-Caribbean men and women.

Common variants of TCF7L2, encoding a beta-cell-expressed transcription factor, are strongly associated with increased risk of type 2 diabetes (T2D). We examined this association using both prospective and case-control designs. A total of 2,676 healthy European white middle-aged men from the prospective NPHSII (158 developed T2D over 15 years surveillance) were genotyped for two intronic SNPs [rs 7903146 (IVS3C>T) and rs12255372 (IVS4G>T)] which showed strong linkage disequilibrium (D' = 0.88, p<0.001; R(2)=0.76, p<0.001). The IVS5T allele frequency was 0.28 (95% CI 0.27-0.29) and 0.33 (0.28-0.39) in healthy and T2D, respectively (p=0.04). Compared to CC men, CT and TT men had an adjusted [for age, body mass index, systolic blood pressure, triglyceride and C-reactive protein levels] hazard ratio for T2D of 1.65 (1.13-2.41) and 1.87 (0.99-3.53), respectively, p<0.01. The population attributable fraction for diabetes risk was 17%. In 1459, European white T2D men and women (60% male), T allele frequency was 0.36 (0.34-0.38), and compared to NPHSII healthy men the OR for T2D for the CT and TT subjects was 1.43 (1.24-1.65) and 2.11 (1.69-2.63), respectively p=<0.0001. A similar effect was observed in 919 T2D Indian Asians [OR=1.50 (1.14-1.99) and 1.64 (1.03-2.63) p=0.003] and 385 Afro-Caribbean subjects [OR=1.25 (0.90-1.75) and 1.32 (0.74-2.33) p=0.17] compared to non-diabetic ethnically matched subjects from South London. Weaker associations were found for the IVS4G>T in all studies. Linkage disequilibrium between the two SNPs was high in Indian Asians (D'=0.94), but much weaker in Afro-Caribbeans (D'=0.17) and haplotype frequencies differed markedly in this group. These results extend previous observations to other ethnic groups, and strongly confirm that TCF7L2 genotype is a major risk factor for development of T2D.

Peroxisome proliferator-activated receptor alpha gene variation influences age of onset and progression of type 2 diabetes.

Dysregulation of fatty acid metabolism is important in the pathogenesis of type 2 diabetes. Peroxisome proliferator-activated receptor (PPAR)alpha is a master regulator of fatty acid catabolism, and PPARalpha activators delay the onset of type 2 diabetes. We examined association between three PPARalpha gene polymorphisms (an A-->C variant in intron 1, the L162V variant, and the intron 7 G-->C variant) and age at diagnosis of type 2 diabetes in 912 Caucasian type 2 diabetic subjects. Individually, PPARalpha gene variants did not influence age at diagnosis, but in combination, the rare alleles of both the intron 1 A-->C (P < 0.001) and intron 7 G-->C (P = 0.025) variants synergistically lowered age at diagnosis (interaction P < 0.001). Overall, the PPARalpha haplotype signficantly influenced age at diagnosis (P = 0.027), with the C-L-C and C-V-C haplotypes (intron 1-L162V-intron 7) accelerating onset of diabetes by 5.9 (P = 0.02) and 10 (P = 0.03) years, respectively, as compared with the common A-L-G haplotype, and was associated with an odds ratio for early-onset diabetes (age at diagnosis

A common variant in the glutathione S transferase gene is associated with elevated markers of inflammation and lipid peroxidation in subjects with diabetes mellitus.

INTRODUCTION: Glutathione S transferases (GST) are enzymes responsible for the metabolism of numerous xenobiotics and play a major cellular antioxidant role. Our aim was firstly, to examine the association between the GST M1/GST mu-1 (GSTM1) and GST T1/GST theta-1 (GSTT1) gene variants with markers of oxidative stress and inflammation in diabetic patients, and secondly to examine the association and potential interaction between these variants and cigarette smoking. METHODS: Seven hundred and seventy-three Caucasian subjects with diabetes and 2592 Caucasian non-diabetic subjects were successfully genotyped. Plasma total antioxidant status, C-reactive protein (CRP), oxidized-LDL (Ox-LDL) and LDL-mean/peak particle diameter were recorded in the diabetes sample. RESULTS: No association was seen between genotype and cardiovascular disease (CVD) risk. In the diabetic subjects, GSTT1-1 compared to GSTT1-0 subjects had significantly higher CRP (p=0.001), Ox-LDL (p=0.004) and smaller LDL particles (p=0.01). In subjects without CVD, there was a significant interaction between the GSTT1-1 variant and smoking in determining Ox-LDL (p=0.04). Furthermore, CVD risk was higher in smokers compared to non-smokers with GSTT1-1. No significant associations were observed by GSTM1. Within the non-diabetic sample, no association was observed between genotype and prospective coronary heart disease (CHD) risk. Of note, the frequency of the GSTT1-1 variant was significantly lower in the diabetes subjects compared to the non-diabetic sample (p=0.01). CONCLUSIONS: This study demonstrates an association between the GSTT1-1 variant and markers of inflammation and lipid peroxidation. Furthermore this variant interacts with smoking to increase lipid peroxidation.

Insight into the nature of the CRP-coronary event association using Mendelian randomization.

BACKGROUND: It is unclear wheather the association between C-reactive protein (CRP) and incident coronary events is free from bias and confounding. Individuals homozygous for a +1444C>T polymorphism in the CRP gene have higher circulating concentrations of CRP. Since the distribution of this polymorphism occurs at random during gamete formation, its association with coronary events should not be biased or confounded. METHODS: We calculated the weighted mean difference in CRP between individuals with variants of the +1444C>T polymorphism in the CRP gene among 4,659 European men from six studies (genotype-intermediate phenotype studies). We used this difference together with data from previous observational studies to compute an expected odds ratio (OR) for non-fatal myocardial infarction (MI) among individuals homozygous for the T allele. We then performed four new genetic association studies (6,201 European men) to obtain a summary OR for the association between the +1444C>T polymorphism and non-fatal MI (genotype-disease studies). RESULTS: CRP was 0.68 mg/l [95% confidence interval (95% CI) 0.31-1.10; P = 0.0001] higher among subjects homozygous for the +1444-T allele, with no confounding by a range of covariates. The expected ORs among TT subjects for non-fatal MI corresponding to this difference in CRP was 1.20 (95% CI 1.07-1.38) using the Reykjavik Heart study data and 1.25 (1.09-1.43) for all observational studies to 2004. The estimate for the observed adjusted-OR for non-fatal MI among TT subjects was 1.01 (95% CI 0.74-1.38), lower than both expected ORs. CONCLUSIONS: A common CRP gene polymorphism is associated with important differences in CRP concentrations, free from confounding. The null association of this variant with coronary events suggests possible residual confounding (or reverse causation) in the CRP-coronary event association in observational studies, though the confidence limits are still compatible with a modest causal effect. Additional studies of genotype (or haplotype) and coronary events would help clarify whether or not the link between CRP and coronary events in observational studies is causal.

A common variant in the ACE gene is associated with peripheral neuropathy in women with type 2 diabetes mellitus.

AIMS: The D allele of the ACE I/D gene variant is associated with higher tissue and serum ACE activity. Previously, studies have suggested an association between the D allele with the microvascular complications of diabetes. The aim of this study was to explore the impact of this genotype in relation to clinically manifest peripheral neuropathy (PN) in a cohort of subjects with type 2 diabetes mellitus (type 2 DM). METHODS: Five hundred and seventy-two Caucasian subjects (230 females, 342 males) with type 2 DM were recruited from the diabetes clinic at University College London Hospitals NHS Trust. Clinically manifest PN was determined from a standardized clinical examination. RESULTS: The ACE I/D genotype distribution was in Hardy-Weinberg equilibrium. In the whole group, no significant association was seen between genotype and PN; however, when stratified by sex, the D allele was associated with PN in females but not in males. The odds ratio (OR) for PN in the D allele carriers compared to those homozygous for the I allele was significantly higher in females [OR 2.93 (1.09-7.63), P=.027] but not in males [OR 1.2 (0.61-2.36), P=.60]. CONCLUSIONS: The presence of the D allele is associated with increased risk of peripheral neuropathy in females but not in male subjects with type 2 DM, suggesting a role for the renin-angiotensin system in the development of PN.

Telomere length, antioxidant status and incidence of ischaemic heart disease in type 2 diabetes.

BACKGROUND: Type 2 diabetes (T2D) is associated with an increased risk of ischaemic heart disease (IHD). An accelerated process of vascular ageing induced by an increased oxidative stress exposure is suggested as potential pathway accounting for this association. However, no studies have explored the relationship between markers of vascular ageing, measures of oxidative stress and risk of IHD in T2D. OBJECTIVES: To explore the association between plasma antioxidant status, marker of cellular ageing (leukocyte telomere length, LTL) and 10years risk of IHD in patients with T2D. METHODS: Between 2001 and 2002, 489 Caucasians subjects with T2D were enrolled at the diabetic clinic, University College London Hospital. Plasma total anti-oxidant status (TAOS) and LTL were measured by photometric microassay and RT-PCR, respectively. The incidence of IHD over 10years was determined through linkage with the national clinical audit of acute coronary syndrome in UK. RESULTS: At baseline, TAOS was associated with LTL (age adjusted: r=0.106, p=0.024). After 10years, 61 patients developed IHD. Lower TAOS and shorter LTL at baseline predicted an increased IHD risk at follow-up (age adjusted: p=0.033 and p=0.040, respectively). These associations were independent of age, gender, cardiovascular risk factors, circulating levels of CRP and medication differences. CONCLUSIONS: Reduced TAOS and short LTL are interrelated pathways which predict risk of IHD in patients with T2D. Our findings suggest that antioxidant defences are important to maintain telomere integrity, potentially reducing the progression of vascular ageing in patients with T2D.

Capnocytophaga spp. in periodontitis patients manifesting diabetes mellitus.

BACKGROUND: The subgingival microflora in patients presenting concurrently with periodontitis and diabetes mellitus (DM) are poorly understood. While traditional putative periodontal pathogens are implicated, research involving other oral organisms; e.g., Capnocytophaga spp., is lacking. These organisms produce a range of bacterial enzymes relevant to periodontal breakdown. It is inferred that periodontal bacteria acquire systemic access through the ulcerated periodontal pocket surface; conclusive evidence supporting this notion is limited. The aims of this investigation were to: 1) quantify and identify Capnocytophaga spp. present in healthy and diseased sites in periodontitis patients with and without DM, and 2) isolate periodontal pathogens from these patients' blood. METHODS: Twenty-one DM-periodontitis and 25 periodontitis patients were recruited. Subgingival plaque was collected from three healthy and three diseased sites per subject. Capnocytophaga spp. and total (facultative and obligate) anaerobic counts from each site were estimated. Capnocytophaga spp. were identified using 16S rRNA polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP). Statistical analyses were performed using multilevel modeling. Blood samples were subjected to HbA(1c) estimation and bacterial culture. RESULTS: A total of 848 Capnocytophaga spp. were isolated and identified. Significantly higher numbers of Capnocytophaga spp. (P <0.001) and anaerobes (P <0.001) were present in diseased sites in DM-periodontitis subjects compared to healthy sites in non-DM-periodontitis and DM-periodontitis subjects. C. ochracea (and variant) and C. granulosa were the most prevalent species. Blood samples were negative for Capnocytophaga spp. CONCLUSIONS: Total mean counts for Capnocytophaga spp. were significantly higher in DM-periodontitis subjects versus non-DM-periodontitis (P = 0.025) and at diseased sites versus healthy sites (P <0.001). Analysis of individual species revealed that the outcome varied with site status and DM status.

An interaction between the interleukin-6 -174G>C gene variant and urinary protein excretion influences plasma oxidative stress in subjects with type 2 diabetes.

BACKGROUND: Microalbuminuria and subsequent progression to proteinuria and nephropathy is associated with increased oxidative stress, increased inflammatory cytokines and increased cardiovascular (CVD) risk. The common functional IL-6 -174G>C gene variant is also associated with elevated levels of inflammatory cytokines and CVD risk. METHODS: The aim of this study was to examine the association between the IL-6 -174G>C gene variant with plasma total antioxidant status (TAOS) in 552 subjects with type 2 diabetes in relation to urinary protein excretion. RESULTS: In subjects free from CVD, there was a significant interaction between urinary protein excretion (normoalbuminuria/ microalbuminuria/proteinuria) and the -174C allele (compared to -174GG) in determining plasma TAOS (p value for interaction = 0.03). In the -174C allele carriers there was a significant association between plasma TAOS and urinary protein excretion: normalbuminuria v microalbuminuria v proteinuria: 44.30% +/- 11.32 vs. 39.74% +/- 14.83 vs. 37.93% +/- 16.42, ANOVA p = 0.025. In those with CVD, no interaction or association was observed with the -174C allele (p = 0.246). CONCLUSION: The IL-6 -174G>C gene variant is associated with differences in plasma oxidative stress in response to altered protein excretion in subjects with type 2 diabetes.

Association between plasma IL-6, the IL6 -174G>C gene variant and the metabolic syndrome in type 2 diabetes mellitus.

Elevated plasma interleukin-6 (IL-6) is associated with coronary heart disease (CHD), impaired glucose tolerance (IGT), and type 2 diabetes (T2DM). We and others have described an association between the human interleukin-6 -174G>C gene variant and body mass index (BMI). Within our previous sample of subjects with T2DM, we measured plasma IL-6 and grouped subjects by the WHO-defined metabolic syndrome, in order to study the association between the -174G>C gene variant, plasma IL-6 and the metabolic syndrome (and component parts). Genotype was obtained in 571 Caucasian subjects with plasma IL-6 measures. There was a significant association between genotype and plasma IL-6 (GG vs GC vs CC: 3.23+/-0.93 pg/ml vs 3.42+/-0.95 pg/ml vs 4.16+/-1.18 pg/ml, p=0.02; for GG/GC vs CC p=0.008). No interactions were observed between genotype and the individual components of the metabolic syndrome in determining plasma IL-6. Increased plasma IL-6 was also associated with the number of components (none vs 1 vs 2 vs > or =3: 2.67+/-0.71 pg/ml vs 2.97+/-0.94 pg/ml vs 4.07+/-1.13 pg/ml, p<0.0001). Within the sample, 76% of CC compared to 56% of GG subjects had the metabolic syndrome (p=0.007). Further analysis of association between the genotype and the components of the metabolic syndrome revealed no further associations than that with BMI previously described. The association of this gene variant with the metabolic syndrome is intimately linked with obesity per se. Further prospective work is required to explore the effect of this gene variant in relation to obesity, the metabolic syndrome and 'prediabetes'.

Tagging SNP haplotype analysis of the secretory PLA2-V gene, PLA2G5, shows strong association with LDL and oxLDL levels, suggesting functional distinction from sPLA2-IIA: results from the UDACS study.

Animal and human studies suggest that both secretory PLA2 (sPLA2)-V and sPLA2-IIA (encoded, respectively, by the neighbouring PLA2G5 and PLA2G2A genes) contribute to atherogenesis. Elevated plasma sPLA2-IIA predicts coronary heart disease (CHD) risk, but no mass assay for sPLA2-V is available. We previously reported that tagging single nucleotide polymorphism (tSNP) haplotypes of PLA2G2A are strongly associated with sPLA2-IIA mass, but not lipid levels. Here, we use tSNPs of the sPLA2-V gene to investigate the association of PLA2G5 with CHD risk markers. Seven PLA2G5 tSNPs genotypes, explaining >92% of the locus genetic variability, were determined in 519 patients with Type II diabetes (in whom PLA2G2A tSNP data was available), and defined seven common haplotypes (frequencies >5%). PLA2G5 and PLA2G2A tSNPs showed linkage disequilibrium (LD). Compared to the common PLA2G5 haplotype, H1 (frequency 34.9%), haplotypes H2-7 were associated with overall higher plasma LDL (P < 0.00004) and total cholesterol (P < 0.00003) levels yet lower oxLDL/LDL (P = 0.006) and sPLA2-IIA mass (P = 0.04), probably reflecting LD with PLA2G2A. Intronic tSNP (rs11573248), unlikely itself to be functional, distinguished H1 from LDL-raising haplotypes and may mark a functional site. In conclusion, PLA2G5 tSNP haplotypes demonstrate an association with total and LDL cholesterol and oxLDL/LDL, not seen with PLA2G2A, thus confirming distinct functional roles for these two sPLA2s.