The 161TT genotype in the exon 6 of the peroxisome-proliferator-activated receptor γ gene is associated with premature acute myocardial infarction and increased lipid peroxidation in habitual heavy smokers

Modifiable and Non-Modifiable Risk Factors for Premature Coronary Heart Disease (PCHD): Systematic Review and Meta-Analysis

AIM

We aimed to compare the prevalence of modifiable and non-modifiable coronary heart disease (CHD) risk factors among those with premature CHD and healthy individuals.

METHODS

PubMed, CINAHL, Embase, and Web of Science databases were searched (review protocol is registered in PROSPERO CRD42020173216). The quality of studies was assessed using the National Heart, Lung and Blood Institute tool for cross-sectional, cohort and case-control studies. Meta-analyses were performed using Review Manager 5.3. Effect sizes for categorical and continuous variables, odds ratio (OR) and mean differences (MD)/standardised mean differences (SMD) with 95% confidence intervals (CI) were reported.

RESULTS

A total of n=208 primary studies were included in this review. Individuals presenting with premature CHD (PCHD, age ≤65 years) had higher mean body mass index (MD 0.54 kg/m2, 95% CI 0.24, 0.83), total cholesterol (SMD 0.27, 95% CI 0.17, 0.38), triglycerides (SMD 0.50, 95% CI 0.41, 0.60) and lower high-density lipoprotein cholesterol (SMD 0.79, 95% CI: -0.91, -0.68) compared with healthy individuals. Individuals presenting with PCHD were more likely to be smokers (OR 2.88, 95% CI 2.51, 3.31), consumed excessive alcohol (OR 1.40, 95% CI 1.05, 1.86), had higher mean lipoprotein (a) levels (SMD 0.41, 95% CI 0.28, 0.54), and had a positive family history of CHD (OR 3.65, 95% CI 2.87, 4.66) compared with healthy individuals. Also, they were more likely to be obese (OR 1.59, 95% CI 1.32, 1.91), and to have had dyslipidaemia (OR 2.74, 95% CI 2.18, 3.45), hypertension (OR 2.80, 95% CI 2.28, 3.45), and type 2 diabetes mellitus (OR 2.93, 95% CI 2.50, 3.45) compared with healthy individuals.

CONCLUSION

This meta-analysis confirms current knowledge of risk factors for PCHD, and identifying these early may reduce CHD in young adults.

The Correlation Between Peroxisome Proliferator-Activated Receptor Alpha and Gamma Polymorphisms and Acute Coronary Syndrome

Objective: This study aims to evaluate the relationship between peroxisome proliferator-activated receptor (PPAR) alpha and gamma gene polymorphisms and acute coronary syndrome (ACS) clinically.

Subject and methods: Peripheral blood samples were collected from a total of 200 people, including 100 acute coronary syndrome patients and 100 controls aged 19 to 93 years, admitted to the Pamukkale University Emergency Medicine Department. The healthy volunteers had no known chronic or acute diseases, no history of drug use, and no recent history of coronary artery disease (CAD). PPAR alpha L162V and PPAR gamma C161T gene polymorphic regions were detected using DNA sequencing analyses. In addition, data collected from the hemogram and biochemical parameters and comorbidities of the patients were statistically analyzed.

Results: PPAR gamma C161T polymorphisms were compared between groups. The CT heterozygous rate in the patient group (74%) was higher than in the control group (7%). The T allele was more common in the patient group (0.37) compared to the control group (0.03). When PPAR alpha L162V polymorphism was compared, VV homozygous individuals were %19 in the patient group and none in the control group. The V allele was found to be statistically higher in patients with ACS (p<0.01).

Conclusion: The findings revealed that elevated PPAR alpha L162V and PPAR gamma C161T gene polymorphisms were associated with a progressive risk of ACS.

PPARγ Gene Polymorphisms, Metabolic Disorders, and Coronary Artery Disease

Being activated by endogenous and exogenous ligands, nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) enhances insulin sensitivity, promotes adipocyte differentiation, stimulates adipogenesis, and has the properties of anti-atherosclerosis, anti-inflammation, and anti-oxidation. The Human PPARγ gene (PPARG) contains thousands of polymorphic loci, among them two polymorphisms (rs10865710 and rs7649970) in the promoter region and two polymorphisms (rs1801282 and rs3856806) in the exonic region were widely reported to be significantly associated with coronary artery disease (CAD). Mechanistically, PPARG polymorphisms lead to abnormal expression of PPARG gene and/or dysfunction of PPARγ protein, causing metabolic disorders such as hypercholesterolemia and hypertriglyceridemia, and thereby increasing susceptibility to CAD.

G Allele of the rs1801282 Polymorphism in PPARγ Gene Confers an Increased Risk of Obesity and Hypercholesterolemia, While T Allele of the rs3856806 Polymorphism Displays a Protective Role Against Dyslipidemia: A Systematic Review and Meta-Analysis

BACKGROUND

The relationships between the rs1801282 and rs3856806 polymorphisms in nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) gene and obesity indexes as well as serum lipid levels have been extensively investigated in various studies, but the results were inconsistent and even contradictory.

METHODS

PubMed, Google Scholar, Embase, Cochrane Library, Web of Science, Wanfang, CNKI and VIP databases were searched for eligible studies. The random-effTPDEects model was used, and standardized mean difference (SMD) with 95% confidence interval (CI) was calculated to estimate the differences in obesity indexes and serum lipid levels between the subjects with different genotypes in a dominant model. Heterogeneity among studies was assessed by Cochran's x²-based Q-statistic test. Publication bias was identified by using Begg's test.

RESULTS

One hundred and twenty studies (70,317 subjects) and 33 studies (18,353 subjects) were identified in the analyses for the rs1801282 and rs3856806 polymorphisms, respectively. The G allele carriers of the rs1801282 polymorphism had higher levels of body mass index (SMD = 0.08 kg/m², 95% CI = 0.04 to 0.12 kg/m², p < 0.001), waist circumference (SMD = 0.12 cm, 95% CI = 0.06 to 0.18 cm, p < 0.001) and total cholesterol (SMD = 0.07 mmol/L, 95% CI = 0.02 to 0.11 mmol/L, p < 0.01) than the CC homozygotes. The T allele carriers of the rs3856806 polymorphism had lower levels of low-density lipoprotein cholesterol (SMD = -0.09 mmol/L, 95% CI = -0.15 to -0.03 mmol/L, p < 0.01) and higher levels of high-density lipoprotein cholesterol (SMD = 0.06 mmol/L, 95% CI = 0.02 to 0.10 mmol/L, p < 0.01) than the CC homozygotes.

CONCLUSIONS

The meta-analysis suggests that the G allele of the rs1801282 polymorphism confers an increased risk of obesity and hypercholesterolemia, while the T allele of the rs3856806 polymorphism displays a protective role against dyslipidemia, which can partly explain the associations between these polymorphisms and cardiovascular disease.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier [CRD42022319347].

C1431T Variant of PPARγ Is Associated with Preeclampsia in Pregnant Women

Peroxisome proliferator-activated receptor γ (PPARγ) is essential for placental development, whose SNPs have shown increased susceptibility to pregnancy-related diseases, such as preeclampsia. Our aim was to investigate the association between preeclampsia and three PPARγ SNPs (Pro12Ala, C1431T, and C681G), which together with nine clinical factors were used to build a pragmatic model for preeclampsia prediction. Data were collected from 1648 women from the EDEN cohort, of which 35 women had preeclamptic pregnancies, and the remaining 1613 women had normal pregnancies. Univariate analysis comparing preeclamptic patients to the control resulted in the SNP C1431T being the only factor significantly associated with preeclampsia (p < 0.05), with a confidence interval of 95% and odds ratio ranging from 4.90 to 8.75. On the other hand, three methods of multivariate feature selection highlighted seven features that could be potential predictors of preeclampsia: maternal C1431T and C681G variants, obesity, body mass index, number of pregnancies, primiparity, cigarette use, and education. These seven features were further used as input into eight different machine-learning algorithms to create predictive models, whose performances were evaluated based on metrics of accuracy and the area under the receiver operating characteristic curve (AUC). The boost tree-based model performed the best, with respective accuracy and AUC values of 0.971 ± 0.002 and 0.991 ± 0.001 in the training set and 0.951 and 0.701 in the testing set. A flowchart based on the boost tree model was constructed to depict the procedure for preeclampsia prediction. This final decision tree showed that the C1431T variant of PPARγ is significantly associated with susceptibility to preeclampsia. We believe that this final decision tree could be applied in the clinical prediction of preeclampsia in the very early stages of pregnancy.

Associations between peroxisome proliferator-activated receptor γ (PPAR-γ) polymorphisms and serum lipids: Two cross-sectional studies of community-dwelling adults

Dyslipidemia is a well-established risk factor for cardiovascular disease. Experimental studies have reported that peroxisome proliferator-activated receptor γ (PPAR-γ) regulates adipocyte differentiation, lipid storage, and glucose metabolism. Therefore, we examined the associations between PPAR-γ polymorphisms (rs1801282, rs3856806, rs12497191, rs1151999, and rs1152003) and serum lipids in two cross-sectional studies. In the Shizuoka area of the Japan Multi-Institutional Collaborative Cohort Study, we examined 4,952 participants (3,356 men and 1,596 women) in a baseline survey and 2,245 participants (1,550 men and 695 women) in a second survey 5 years later. Outcome measures were the prevalence of dyslipidemia (low-density lipoprotein-cholesterol [LDL-C] ≥ 140 mg/dl, high-density lipoprotein-cholesterol < 40 mg/dl, triglycerides ≥ 150 mg/dl, and/or use of cholesterol-lowering drugs) and the prevalence of high LDL-C (LDL-C ≥ 140 mg/dl and/or use of cholesterol-lowering drugs). Multivariate odds ratios (ORs) were estimated by using unconditional logistic regression models. A total of 2,114 and 1,431 individuals (42.7% and 28.9%) had dyslipidemia and high LDL-C in the baseline survey, respectively, as did 933 and 716 (41.6% and 31.9%), respectively, in the second survey. In the baseline study, compared with major allele homozygotes, minor allele homozygotes of rs3856806 and rs12497191 had a 42% (OR, 0.58; 95% confidence interval (CI), 0.39-0.85) and 23% (OR, 0.77; 95% CI, 0.60-0.99) lower risk of dyslipidemia, respectively, after adjustment for potential confounding factors. In addition, minor allele homozygotes of rs3856806 had a 45% (OR, 0.55; 95% CI, 0.35-0.86) lower risk of high LDL-C. Similar risk reductions were found in the second survey. In conclusion, rs3856806 and rs12497191 polymorphisms may be related to a lower risk of dyslipidemia and high LDL-C.

Polymorphism related to cardiovascular risk in hemodialysis subjects: a systematic review

Cardiovascular disease (CVD) is one of the leading causes of mortality in hemodialysis (HD) subjects. In addition to the traditional risk factors that are common in these individuals, genetic factors are also involved, with emphasis on single nucleotide polymorphs (SNPs). In this context, the present study aims to systematically review the studies that investigated the polymorphisms associated with cardiovascular risk in this population. In general, the SNPs present in HD individuals are those of genes related to inflammation, oxidative stress and vascular calcification, also able of interfering in the cardiovascular risk of this population. In addition, polymorphisms in genes related to recognized risk factors for CVD, such as dyslipidemia, arterial hypertension and left ventricular hypertrophy, also influence cardiovascular morbidity and mortality.

PON2 and PPARG polymorphisms as biomarkers of risk for coronary heart disease

Aim: Investigate the correlation between paraoxonase 2 (PON2) Ser311Cys polymorphism as well as the peroxisome proliferator-activated receptor gamma (PPARG) His477His polymorphism and the susceptibility to development of coronary heart diseases (CHD) through a meta-analysis. Methods: Odds ratio and the corresponding 95% CI were used to assess the results. We included 7476 CHD patients and 8504 healthy controls. All the statistical analyses were performed by Comprehensive Meta-Analysis software (CMA, version 2.0). Results: The Ser311Cys polymorphism decreased susceptibility in the overall population and Asian population to CHD. The His477His polymorphism has a protective role in the overall population; however, the subgroup analysis by ethnicity suggested that in Asian population, His477His might increase the risk of CHD. Conclusion: These polymorphisms constitute important predictive indicators of CHD susceptibility.

PPARγ2 C1431T Polymorphism Interacts with the Antiobesogenic Effects of Kochujang, a Korean Fermented, Soybean-Based Red Pepper Paste, in Overweight/Obese Subjects: A 12-Week, Double-Blind Randomized Clinical Trial

Kochujang, a Korean fermented soybean-based red pepper paste, has been reported to have beneficial health effects. The aim of this study was to examine the antiobesity effects of Kochujang as a supplement in overweight/obese subjects according polymorphisms in the obesity-linked gene, peroxisome proliferator activator receptor γ (PPARγ2). Sixty overweight/obese subjects, who had body mass indexes (BMI, kg/m2) ≥23 or waist/hip ratios (WHR) ≥0.90 for males or ≥0.85 for females, were randomly assigned to either taking 32 g/day of placebo or Kochujang for 12 weeks. Before and after the intervention, anthropometric and metabolic parameters and body fat distribution (by computed tomography) were measured. After PPARγ2 C1431T polymorphism was analyzed by PCR-restriction fragment length polymorphism, the differences among the four groups (wild and mutant alleles in Kochujang and placebo groups) were determined. Between the Kochujang (n = 26) and placebo (n = 27) groups, there were no differences in body composition, insulin resistance, or antioxidant biomarkers before and after intervention. Compared to placebo, Kochujang significantly decreased plasma triglyceride (TG), TG/high-density lipoprotein (HDL), and dietary intakes of protein, sodium, and potassium after age, sex, and BMI were adjusted. The beneficial effects of Kochujang on lowering of TG and TG/HDL were weakened in subjects with the PPARγ2 mutant T allele with increasing subcutaneous fat area. However, the interaction between Kochujang and the PPARγ2 T allele improved insulin sensitivity. The obesogenic variables affected by the T mutant allele of PPARγ2 C1431T SNP were different in overweight/obese subjects in response to Kochujang.

Nutrigenomic Functions of PPARs in Obesogenic Environments

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that mediate the effects of several nutrients or drugs through transcriptional regulation of their target genes in obesogenic environments. This review consists of three parts. First, we summarize current knowledge regarding the role of PPARs in governing the development of white and brown/beige adipocytes from uncommitted progenitor cells. Next, we discuss the interactions of dietary bioactive molecules, such as fatty acids and phytochemicals, with PPARs for the modulation of PPAR-dependent transcriptional activities and metabolic consequences. Lastly, the effects of PPAR polymorphism on obesity and metabolic outcomes are discussed. In this review, we aim to highlight the critical role of PPARs in the modulation of adiposity and subsequent metabolic adaptation in response to dietary challenges and genetic modifications. Understanding the changes in obesogenic environments as a consequence of PPARs/nutrient interactions may help expand the field of individualized nutrition to prevent obesity and obesity-associated metabolic comorbidities.

Association between peroxisome proliferator-activated receptor-alpha, delta, and gamma polymorphisms and risk of coronary heart disease: A case-control study and meta-analysis

OBJECTIVES

Risk of coronary heart disease (CHD) has been suggested to be associated with polymorphisms of peroxisome proliferator-activated receptors (PPARs), while the results were controversial. We aimed to systematically assess the association between PPAR polymorphisms and CHD risk.

METHODS

A case-control study with 446 subjects was conducted to evaluate the association between CHD risk and C161T polymorphism, which was of our special interest as this polymorphism showed different effects on risks of CHD and acute coronary syndrome (ACS). Meta-analyses were conducted to assess all PPAR polymorphisms. Either a fixed- or a random-effects model was adopted to estimate overall odds ratios (ORs).

RESULTS

In the case-control study, T allele carriers of C161T polymorphism were not significantly associated with CHD risk (Odds ratio (OR) = 0.74, 95% confidence interval (CI) 0.47-1.15, P = 0.19), while T allele carriers showed higher risk of ACS (OR = 1.63, 95% CI 1.00-2.65, P = 0.048). The meta-analysis indicated that compared with CC homozygous, T allele carriers had lower CHD risk (OR = 0.69, 95% CI 0.59-0.82, P < 0.001) but higher ACS risk (OR = 1.43, 95% CI 1.09-1.87, P = 0.010). Three other polymorphisms were also found to be significantly associated with CHD risk under dominant model: PPAR-alpha intron 7G/C polymorphism (CC+GC vs GG, OR 1.42, 95% CI 1.13-1.78, P = 0.003), L162V polymorphism (VV+LV vs LL, OR 0.74, 95% CI 0.56-0.97, P = 0.031), and PPAR-delta +294T/C polymorphism (CC+TC vs TT, OR 1.51, 95% CI 1.12-2.05, P = 0.007).

CONCLUSIONS

The results suggested that PPAR-alpha intron 7G/C and L162V, PPAR-delta +294T/C and PPAR-gamma C161T polymorphisms could affect CHD susceptibility, and C161T polymorphism might have different effects on CHD and ACS.

Impact of the C1431T Polymorphism of the Peroxisome Proliferator Activated Receptor-Gamma (PPAR-γ) Gene on Fasted Serum Lipid Levels in Patients with Coronary Artery Disease

BACKGROUND/AIMS

The C1431T polymorphism of peroxisome proliferator activated receptor-γ (PPAR-γ) gene is related to diabetes and metabolic-syndrome. However, studies have been inconclusive about its association with coronary artery disease (CAD) and there have been no studies analyzing the association of this polymorphism with fasted-serum-lipid levels in Iranian-individuals with CAD. We investigated the association of PPAR-γ C1431T-polymorphism with CAD and dyslipidaemia in 787 individuals.

METHODS

Anthropometric-parameters and biochemical-measurements were evaluated, followed by genotyping. The association of the genetic-polymorphisms with CAD and lipid-profile was determined by univariate/multivariate-analyses.

RESULTS

Patients with CT or CT+TT genotype were at an increased-risk of CAD relative to CC-carriers (adjusted odds ratio: 2.03; 95% confidence interval, 1.01-4.09; p = 0.046). However, in the larger population, CT genotype was present at a higher frequency in the group with a positive angiogram. Furthermore, CT+TT genotypes were associated with an altered fasted-lipid-profile in the initial population sample of patients with a positive angiogram, compared to the group with a negative-angiogram. The angiogram-positive patients carrying the T allele had a significantly higher triglyceride, serum C-reactive protein and fasting-blood-glucose.

CONCLUSION

We have found the PPAR-γ C1431T polymorphism was significantly associated with fasted serum lipid profile in individuals with angiographically defined CAD. Since accumulating data support the role of PPAR-γ polymorphisms in CAD, further studies are required to investigate the association of this polymorphism with coronary artery disease.

Association between Peroxisome Proliferator-activated Receptor Gamma Gene Polymorphisms and Atherosclerotic Diseases: A Meta-analysis of Case-control Studies

AIM

The aim of this study was to perform a meta-analysis to investigate the association between PPARγ rs1801282/rs3856806 polymorphisms and atherosclerotic diseases.

METHODS

The meta-analysis was performed by searching the PubMed, Embase and Web of Science databases from the first available year to September 10, 2013. Additionally, reference lists from the identified articles, reviews and abstracts presented at the meetings of related scientific societies were also checked. All case-control studies investigating the association between PPARγ rs1801282/rs3856806 polymorphisms and the risk of atherosclerotic disease were included. The association was assessed according to the odds ratio (OR) with a 95% confidence interval (CI). Publication bias was analyzed using Begg's funnel plot and Egger's regression test.

RESULTS

A total of 29 studies reporting PPARγ rs1801282/rs3856806 polymorphism were included in the final meta-analysis. Neither the rs1801282 (Pro12Ala) nor rs3856806 (C161T) polymorphisms showed any significant associations with susceptibility to atherosclerotic diseases. In the meta-analysis performed to assess the association between the rs3856806 gene polymorphism and atherosclerotic disease based on ethnicity and the type of disease, significant associations were found in the Caucasian subgroup, Asian, CAD and MI subgroups.

CONCLUSIONS

The present data suggest that there is no statistical evidence of a significant association between the PPARγ gene rs1801282/rs3856806 polymorphism and the risk of atherosclerotic disease. In contrast, the rs3856806 polymorphism was associated with an increased risk in the Caucasian and MI subgroups, whereas decreased risks were noted in the Asian and CAD subgroups. Due to significant between-study heterogeneity, further studies with a larger sample size involving homogeneous AS patients and well-matched controls are required in the future.

Association of the variants in the PPARG gene and serum lipid levels: a meta-analysis of 74 studies

Considerable studies have been carried out to investigate the relationship between the polymorphisms of PPARG (Pro12Ala, C161T and C1431T) and serum lipid levels, but the results were inconclusive. Hence, we conducted a meta-analysis to clarify the association. MEDLINE, EMBASE and the Cochrane Library databases were searched systematically. The subgroup analysis was performed based on ethnicity. Seventy-four studies with 54,953 subjects were included in this meta-analysis. In Pro12Ala, the group with the ‘PP’ (C/C genotype) genotype group had lower levels of total cholesterol (TC) (mean difference, MD: −0.02, P < 0.00001; I² = 28%), low-density lipoprotein cholesterol (LDL-C) (MD: −0.02, P < 0.00001; I² = 30%) and higher levels of triglyceride (TG) (MD: 0.06, P < 0.00001; I² = 30%) than the combined ‘PA+AA’ (PA = C/G genotype, AA = G/G genotype) genotype group in Asian population, and the group with the ‘PP’ genotype had higher levels of TG (MD: 0.07, P < 0.02; I² = 67%) than the combined ‘PA+AA’ genotype group in non-Asian population. No statistically significant differences in the levels of TC, TG, high-density lipoprotein cholesterol, LDL-C were detected between different genotypes in C161T(Asian or non-Asian) and C1431T(Asian) polymorphisms. This meta-analysis was a renewed and confirmed study to assess the association between PPARG polymorphisms and serum lipid levels in Asian and non-Asian populations. There is a prominent association between Pro12Ala polymorphism and the levels of TC, LDL-C and TG in Asian population. No statistically significant differences in serum lipid levels were detected between different genotypes in C161T and C1431T polymorphisms.

Association of peroxisome proliferator-activated receptorγ gene Pro12Ala and C161T polymorphisms with cardiovascular risk factors in maintenance hemodialysis patients

The Pro12Ala and C161T polymorphisms in peroxisome proliferator-activated receptor γ (PPARγ) have been shown to be associated with carotid artery atherosclerosis. It remains unclear whether these two polymorphisms are associated with risk factors for cardiovascular disease (CVD) in hemodialysis (HD) patients. Therefore, the PPARγ genotypes in 99 HD patients and 149 controls were determined, and clinical characteristics among the different genotypes were compared. We found that the frequency of the Pro12Ala and C161T polymorphisms in HD patients was similar to that in healthy controls, but C161T polymorphism and T allele frequencies in HD patients with CVD were lower than that in HD patients without CVD. Carotid artery plaque (CAP) and carotid intima-media thickness (CIMT) in HD patients with CT + TT or Pro12Ala genotypes were also less than that in patients with CCor Pro12Pro genotypes, respectively. HD patients with CT + TT genotype had lower serum C reactive protein (CRP) levels, as well as higher triceps skin fold (TSF) thickness, mid arm circumference (MAC) and mean mid arm circumference (MMAC) than HD patients with CC genotype (P < 0.05). Moreover, CIMT of the Pro12Ala-CT161 subgroup was less than the Pro12Pro-CC161 and Pro12Pro-CT161 subgroup, and, CAP amounts of the Pro12Ala-CT161 subgroup was less than the Pro12Pro-CC161 subgroup. Our results indicate that the Pro12Ala and C161T polymorphisms were associated with some important risk factors for CVD in HD patients in the Han Chinese population.

Effect of the PPARγ C161T gene variant on serum lipids in ischemic stroke patients with and without type 2 diabetes mellitus

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor involved in the regulation of lipid metabolism, diabetes, obesity, atherogenesis and inflammation. PPARγ genetic variation has been associated with metabolic and cardiovascular diseases. The aim of this study was to explore, for the first time, the relationship between PPARγ C161T polymorphism and the risk of ischemic stroke (IS) among patients with type 2 diabetes mellitus (T2DM). A total of 196 patients with IS (117 diabetics and 79 nondiabetics) and 192 controls were recruited to enroll in this study. PPARγ C161T genotyping was performed by PCR-RFLP technique. The 161T allele as compared with C allele was found to be higher in controls than in IS patients (with or without T2DM). After adjusting for multiple risk factors, the T allele carriers had significantly reduced IS risk (OR=0.575, 95% CI 0.348-0.951, p=0.030) compared to the CC homozygotes which increased significantly the risk in IS patients with T2DM (OR=1.85, 95% CI 1.23-2.62). Moreover, the triglycerides (TG) and ApoB levels in CC homozygote carriers were significantly higher than those in T allele carriers. These results indicate that the C161T of PPARγ may reduce the risk of IS by modulation of adipose metabolism especially TG and ApoB in IS patients with T2DM.

Doenjang, a Korean fermented soy food, exerts antiobesity and antioxidative activities in overweight subjects with the PPAR-γ2 C1431T polymorphism: 12-week, double-blind randomized clinical trial

We examined the antiobesity and antioxidant effects of supplementation with doenjang, a fermented soybean paste, in overweight Koreans with the PPAR-γ2 C1431T polymorphism. Sixty overweight subjects were randomly assigned to consume either 9.8 g/day of doenjang or placebo for 12 weeks. Before and after the intervention, anthropometric and metabolic parameters, along with abdominal fat distribution and PPAR-γ2 polymorphisms, were measured. Fifty-one subjects completed the study, doenjang (n=26) and placebo (n=25) groups. Relative frequencies of the PPAR-γ2 genotypes CC, TC, and TT were 70% (n=41), 25.9% (15), and 3.4% (2), whereas those of the PPAR-γ2 alleles C and T were 81.6% and 18.4%. Visceral fat area (VFA) was significantly decreased by doenjang supplementation in subjects with a mutant T allele of PPAR-γ2 compared to those with a C allele after adjusting for age, sex, and body mass index. Plasma free fatty acid, insulin, and homeostatic model assessment insulin resistance (HOMA-IR) levels were also significantly increased in the doenjang group. Doenjang pills significantly activated radical clearance capacity (ORAC and DNA tail length) in subjects with the C allele. The catalase (CAT) activity was increased twofold in the doenjang-treated group with the C allele, but this phenomenon was reversed in those with the T allele. Doenjang-treated subjects tended to have low dietary carbohydrate and sodium intakes compared with those given placebo. We found that doenjang supplementation decreased visceral fat accumulation and aging most effectively in subjects with PPAR-γ polymorphisms. This study suggests that doenjang has antiobesity and antioxidative effects in overweight individuals with mutant alleles of PPAR-γ2.

The C161T polymorphism in the peroxisome proliferator-activated receptor gamma gene (PPARγ) is associated with risk of coronary artery disease: a meta-analysis

The researches attempting to associate the PPARγ C161T polymorphism with coronary artery disease (CAD) yielded complicated and contradictory results. We aimed for more precise estimate of the relationship and conducted a comprehensive meta-analysis. Publications written in English or Chinese were screened in MEDLINE, Embase, CNKI, Wanfang and CBM. Data on 11 studies including 3,020 cases and 2,853 controls were extracted. A random-effects model was available to synthesize the inconsistent outcomes of the individual studies, while addressing between-study heterogeneity and publication bias. The PPARγ C161T polymorphism followed Hard-Weinberg Equilibrium for all studies (P > 0.05).Overall, there was no evidence for a significant association under all genetic models but with distinct heterogeneity (T vs. C: P = 0.29, OR = 0.91, 95 %CI 0.77-1.08, P heterogeneity = 0.004, I (2) = 61.2 %). However, in the subgroup analysis by ethnicity, the T allele carriers showed a prominent 26 % risk reduction of CAD among Chinese (dominant genetic model: P = 0.03, 95 %CI 0.57-0.97, P heterogeneity = 0.03, I (2) = 56.1 %). After dividing into population source, the significance of CAD risk reduction was strengthened in hospital-based studies (allele comparison: P = 0.04, OR = 0.82, 95 %CI 0.67-1.00, P heterogeneity = 0.04, I (2) = 52.5 %; dominant model: P = 0.01, OR = 0.73, 95 %CI 0.57-0.92, P heterogeneity = 0.05, I (2) = 50.8 %). There was no obvious publication bias verified in the method of funnel plot and Egger's linear regression test (t = -0.11, P = 0.913). Taken together, our results revealed the PPARγ C161T polymorphism might play a moderate protective effect on developing CAD among Chinese, but not among Caucasians.

The effect of PPARG gene polymorphisms on the risk of coronary heart disease: a meta-analysis

The peroxisome proliferator-activated receptor-γ (PPARG) is a member of the nuclear hormone receptor superfamily that has attracted considerable attention as a candidate gene for coronary heart disease (CHD) based on its function as a key factor involved in the regulation of lipid and glucose metabolism. In the past decade, a number of case-control studies have been carried out to investigate the relationship between the PPARG polymorphisms and CHD. However, these studies have yielded contradictory results. To derive a more precise estimation of the relationship, a meta-analysis of 33 studies including a total of 12,340 cases and 17,471 controls on 3 PPARG polymorphisms (Pro12Ala, C161T and C1431T) was performed. In a combined analysis, the summary per-allele odds ratio for CHD was 1.02 (95 % CI: 0.93-1.13), 0.86 (95 % CI: 0.72-1.02), and 0.92 (95 % CI: 0.74-1.16) for PPARG 12Ala, 161T and 1431T alleles, respectively. No significant results were observed under dominant or recessive genetic models for these polymorphisms in almost all comparisons. In the stratified analyses according to ethnicity, sample size, CHD endpoints and HWE status, no evidence of any gene-disease association was obtained. Our results suggest that the Pro12Ala, C161T and C1431T polymorphisms of PPARG gene are not associated with CHD susceptibility.

The meta-analysis of the association of PPARG P12A, C161T polymorphism and coronary heart disease

OBJECTIVE

Two common variations of peroxisome proliferator-activated receptor γ (PPARG), P12A (Pro12Ala, rs1801282), and C161T (His447His, rs3856806), are thought to have an effect on susceptibility to coronary heart disease (CHD), but the results are inconsistent. Therefore, a meta-analysis of published studies was performed.

METHODS

The electronic databases, PubMed, Embase, Web of Science, and CNKI (China National Knowledge Infrastructure) were searched for studies to include in the present meta-analysis (last search was updated on 30 Aug. 2011). Twenty studies testing the association between PPARG gene polymorphisms and CHD were examined: 12 studies of P12A; 8 studies of C161T. Overall and ethnicity-specific summary odds ratios and corresponding 95 % confidence intervals for CHD associated with these polymorphisms were estimated using fixed- and random-effects models. Heterogeneity and publication bias were evaluated. A total of 20 studies including 5,795 cases and 9,069 controls were included in this meta-analysis.

RESULTS

No significant associations were found in carriers of the rare Ala allele of the P12A polymorphism versus the common Pro/Pro genotype among the studies with both of the fixed-effect and random-effect model. In the subgroup analyses by ethnicity, source of control and type of study, no significant risks were found. For PPARG C161T, carriers of the T variant of C161T polymorphism were associated with an increased risk of CHD (OR = 1.182, 95 % CI: 1.023-1.341, P(heterogeneity) = 0.002), and in the stratified analysis by ethnicity and source of controls, the contrast of CT + TT vs. CC all produced significant association in Asian and hospital-based controls (OR = 1.276, 95 % CI: 1.084-1.468, P(heterogeneity) = 0.055; OR = 1.164, 95 % CI: 1.001-1.326, P(heterogeneity) = 0.002),when the fixed-effect model was used. But they were all insignificant with the random-effect model.

CONCLUSION

This meta-analysis suggests that the PPARG C161T polymorphism marginally contributes to increased susceptibility to CHD and marginally increased association between PPARG H477H polymorphism and CHD also appeared in Asian and hospital-based controls. But PPARG P12A polymorphism is not associated with CHD risk.

The Impact of PPARγ Genetic Variants on IBD Susceptibility and IBD Disease Course

PPARγ is a nuclear receptor that regulates numerous pathways including cytokine expression and immune responses and plays an important role in controlling colon inflammation. We aimed at determining the occurring PPARγ SNPs, at predicting the haplotypes, and at determining the frequency outcome in inflammatory bowel disease (IBD) patients in comparison with healthy controls. We determined genetic variants in the coding exons and flanking intronic sequences of the NR1C3 gene in 284 IBD patients and 194 controls and predicted NR1C3 haplotypes via bioinformatic analysis. We investigated whether certain NR1C3 variants are associated with susceptibility to IBD or its disease course. None of the detected 22 NR1C3 variants were associated with IBD. Two variants with allelic frequencies over 1% were included in haplotype/diplotype analyses. None of the NR3C1 haplotypes showed association with IBD development or disease course. We conclude that NR1C3 haplotypes are not related to IBD susceptibility or IBD disease activity.

Effects of the PPARG P12A and C161T gene variants on serum lipids in coronary heart disease patients with and without Type 2 diabetes

We investigated whether PPAR-γ2 gene polymorphisms are associated with serum lipids and the occurrence of coronary heart disease (CHD) prospectively characterised for the presence or absence of Type 2 diabetes in a Turkish population. Our study included 202 patients with CHD (102 with diabetes, 100 without diabetes) and 105 controls. PPARγ genotypes were determined by PCR-RFLP technique. The PPARγ-C161T CC homozygote genotype was associated with significantly increased CHD risk when compared with the T allele carriers (CT+TT) in CHD patients with diabetes (OR:1.951, 95%CI: 1.115-3.415, P = 0.019), whereas PPARγ-P12A polymorphism was not associated with CHD risk (P > 0.05). Serum HDL-C levels were significantly lower in controls with the P12A heterozygote when compared with the P12P homozygote (P = 0.002). In the CHD patients with diabetes, CT heterozygote genotype showed higher serum triglyceride than the CC homozygote genotype (CT:2.42 ± 1.89 vs. CC:1.61 ± 0.21, P = 0.015). Our findings shows the association of these two polymorphisms with serum triglyceride levels, which was increased in the order of P12P-CC < P12P-CT < P12A-CC < P12A-CT in the CHD patients with diabetes. Furthermore, we observed that the increasing effects of the CT genotype on serum triglyceride levels could be modified by PPARγ P12A polymorphism (P12A-CT:2.30 ± 1.75 vs. P12P-CC:1.79 ± 1.14, P = 0.028). We suggested that homozygote CC genotype of the PPARγ C161T polymorphism might be associated with an increased CHD risk especially in patients with diabetes. We observed that the C161T CT heterozygote genotype shows an unfavorable effect on serum lipid profile in CHD patients with diabetes and this effect was weaken with the presence of P12P homozygote genotype.

PPAR Genomics and Pharmacogenomics: Implications for Cardiovascular Disease

The peroxisome proliferator-activated receptors (PPARs) consist of three related transcription factors that serve to regulate a number of cellular processes that are central to cardiovascular health and disease. Numerous pharmacologic studies have assessed the effects of specific PPAR agonists in clinical trials and have provided insight into the clinical effects of these genes while genetic studies have demonstrated clinical associations between PPAR polymorphisms and abnormal cardiovascular phenotypes. With the abundance of data available from these studies as a background, PPAR pharmacogenetics has become a promising and rapidly advancing field. This review focuses on summarizing the current state of understanding of PPAR genetics and pharmacogenetics and the important implications for the individualization of therapy for patients with cardiovascular diseases.

Distribution of peroxisome proliferator-activated receptor-gamma polymorphisms in Chinese and Dutch patients with inflammatory bowel disease

BACKGROUND

As peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is frequently expressed in colon, its genetic polymorphism may play a role in the etiology of inflammatory bowel disease (IBD). The aims of the present study were to determine the distribution of PPAR-gamma polymorphisms Pro12Ala and C161T and to explore the association between the PPAR-gamma genotypes and phenotypes of IBD patients.

METHODS

A total of 244 IBD patients [212 ulcerative colitis (UC) and 32 Crohn's disease (CD)] and 220 controls in the Chinese population and 603 IBD patients (302 UC and 301 CD) and 180 controls in the white Dutch population were enrolled in the study. The phenotypes of Chinese IBD patients were grouped according to disease location. The PPAR-gamma polymorphisms Pro12Ala and C161T were genotyped by PCR-based methods.

RESULTS

In the Chinese population, T carriers of the PPAR-gamma C161T polymorphism were more common in UC patients than in the controls [37.7% vs. 25.5%, odds ratio 1.77, 95% confidence interval 1.18-2.68, P = 0.007], whereas Ala carriers of the Pro12Ala polymorphism showed no significant association in UC patients, but there was a significant association of Ala carriers with more extensive disease among the UC patients (P = 0.002); Pro12Ala and C161T genotypes did not show any associations with CD patients. No associations were found for the PPAR-gamma C161T SNP studied in the Dutch IBD population.

CONCLUSIONS

Our study showed the potential association between the PPAR-gamma C161T polymorphism and UC patients in the central Chinese population. This finding was not replicated in the Dutch population. Further studies are necessary to explore the functional implication of the PPAR-gamma C161T polymorphism in Chinese UC patients.

Characterization of a novel polymorphism in PPARG regulatory region associated with type 2 diabetes and diabetic retinopathy in Italy

Peroxisome proliferator-activated receptor gamma polymorphisms have been widely associated with type 2 diabetes, although their role in the pathogenesis of vascular complications is not yet demonstrated. In this study, a cohort of 211 type 2 diabetes, 205 obese, and 254 control individuals was genotyped for Pro12Ala, C1431T, C-2821T polymorphisms, and for a newly identified polymorphism (A-2819G). The above-mentioned polymorphisms were analyzed by gene-specific PCR and direct sequencing of all samples. A significant difference was found for -2819G frequency when patients with type 2 diabetes—particularly diabetic women with the proliferative retinopathy—were compared with healthy control individuals. In conclusion, we identified a novel polymorphism, A-2819G, in PPARG gene, and we found it to be associated with type 2 diabetes and proliferative retinopathy in diabetic females. In the analyzed population, this variant represents a genetic risk factor for developing the diabetic retinopathy, whereas Pro12Ala and C1431T do not.

PPAR transcriptional activator complex polymorphisms and the promise of individualized therapy for heart failure

The PPAR gene pathway consists of interrelated genes that encode transcription factors, enzymes, and downstream targets which coordinately act to regulate cellular processes central to glucose and lipid metabolism. The pathway includes the PPAR genes themselves, other class II nuclear hormone receptor transcription factors within the PPAR family, PPAR co-activators, PPAR co-repressors, and downstream metabolic gene targets. This review focuses on the transcription factors that comprise the PPAR transcriptional activator complex--the PPARs (PPARalpha, PPARbeta, or PPARgamma), PPAR heterodimeric partners, such as RXRalpha, and PPAR co-activators, such as PPARgamma coactivator 1alpha (PGC-1alpha) and the estrogen-related receptors (ERRalpha, ERRbeta, and ERRgamma). These transcription factors have been implicated in the development of myocardial hypertrophy and dilated cardiomyopathy as well as response to myocardial ischemia/infarction and, by association, ischemic cardiomyopathy. Human expression studies and animal data are presented as the background for a discussion of the emerging field of pharmacogenetics as it applies to these genes and the consequent implications for the individualization of therapy for patients with heart failure.

Peroxisome proliferator-activated receptors and inflammation: take it to heart

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors acting as key regulators of lipid metabolism as well as modulators of inflammation. The role of PPARalpha and PPARgamma in cardiac ischaemia-reperfusion injury, infarct healing and hypertrophy is the subject of intense research. Due to the later development of PPARdelta-specific ligands, the role of this PPAR isoform in cardiac disease remains to be established. Although many studies point to salutatory effects of PPAR ligands in cardiac disease, the exact molecular mechanism is still largely unsolved. Both the metabolic (via transactivation) and the more recently discovered anti-inflammatory (via transrepression) effects of PPARs are likely to play a role. In this review the reported, and sometimes contradictory, effects of PPAR ligands on ischaemia-reperfusion, infarct healing and cardiac hypertrophy are critically evaluated. In particular the role of inflammation in these disease processes, the ability of PPARs to interfere with pro-inflammatory processes, and the mechanisms of transrepression are discussed. Currently, the significance of PPARs as therapeutic targets in cardiovascular disease is receiving widespread attention. Accordingly, detailed understanding of the mechanisms controlling the activity of these nuclear hormone receptors is essential.

Variants of the peroxisome proliferator-activated receptor gamma- and beta-adrenergic receptor genes are associated with measures of compensatory eating behaviors in young children

BACKGROUND

Young children can regulate energy precisely in the short term, showing the potential for an innate compensation mechanism of eating behavior. However, data suggest that precise compensation is attenuated as a function of increasing adiposity, parental feeding style, and age. Common variation in candidate obesity genes may account for some of the individual variation observed in short-term energy compensation. Polymorphisms in the peroxisome proliferator-activated receptor gamma (PPARG) and beta-adrenergic receptor (ADRB3) genes have been linked to increased body mass index (BMI; in kg/m(2)), obesity, and more recently dietary nutrients and preferences. In addition, common variation in ADRB3 interacts with PPARG to modulate adult body weight.

OBJECTIVE

This study investigated whether variants in these genes were associated with measurable effects on child eating behavior.

DESIGN

Children (n=84) aged 4-10 y were prospectively selected for variants of the PPARG locus (Pro12Ala, C1431T). Heights and weights were measured. Energy intake from a test meal was measured 90 min after ingestion of a no-energy (NE), low-energy (LE), or high-energy (HE) preload, and the compensation index (COMPX) was calculated.

RESULTS

BMI differed significantly by gene model, whereby Pro12Ala was associated with a lower BMI. Poor COMPX was associated with the PPARG T1431 allele (P=0.009). There was a significant interaction between COMPX and the ADRB3 Trp64Arg variant in modulating compensation (P=0.003), whereas the Arg64 allele was associated with good compensation (P=0.001).

CONCLUSIONS

This is the first study to suggest that a genetic interaction involving ADRB3 and PPARG variants influences eating behavior in children.

Energy balance and food intake: the role of PPARgamma gene polymorphisms

Mechanisms regulating energy balance involve complex interactions between genetic, environmental and behavioural (learnt and intrinsic) factors. Genotype may drive the partitioning of energy metabolism and predispose to site-specific adiposity, culminating in a state of energy imbalance. One candidate gene with a direct link to adiposity is the peroxisome proliferator-activated receptor gamma (PPARG) gene. PPARG is a cell nuclear receptor expressed almost exclusively in adipose tissue that regulates adipocyte differentiation, lipid metabolism and insulin sensitivity. PPARgamma appears to be a key regulator of energy balance, with polymorphisms on the PPARG gene linked to obesity and effects on body composition. Our research has confirmed an association between the pro12ala allele and reduced incidence of obesity in pre-pubertal children and there are strong associations between genetic variation at the PPARG locus and percentage body fat. Moreover, our evidence suggests that PPARG C-681G and pro12ala polymorphisms display opposing effects in terms of growth phenotype, with pro12Ala associated with deficient energy utilisation, leading to reduced growth and the G-681 variant associated with accelerated growth compared with wildtypes. Common differences in this gene have also been associated with variations in body weight in response to dietary macronutrients. Preliminary evidence suggests that PPARG variants may even be involved in the control of short term energy compensation. Taken together these data suggest that the role of PPARG is varied and complex, influencing fat deposition and growth velocity early in life, with potential impact in the control of energy intake and appetite regulation, and could provide a key target for future research and anti-obesity agents.

The PPAR genes, cardiovascular disease and the emergence of PPAR pharmacogenetics

The peroxisome proliferator-activated receptors (PPARs) comprise a group of related transcription factors that serve to regulate a number of cellular processes that are central to cardiovascular health and disease. Two large bodies of work strongly implicate the PPARs as key factors in normal cardiovascular physiology and in cardiovascular pathophysiology: i) studies demonstrating associations between PPAR and abnormal cardiovascular phenotypes; and ii) pharmacological studies assessing the effects of specific PPAR agonists in clinical trials. With the abundance of data available from these studies as a background, PPAR pharmacogenetics has become a promising and rapidly-advancing field. This review summarises the current state of understanding of PPAR pharmacogenetics and its profound implications for the individualisation of therapy for patients with a diverse group of cardiovascular diseases.

The Pro12Ala and C-681G variants of the PPARG locus are associated with opposing growth phenotypes in young schoolchildren

AIMS/HYPOTHESIS

Peroxisome proliferator-activated receptor gamma is an important regulator of adiposity in mouse and man, and common variation in the PPARG gene has been associated with birthweight, adult obesity, insulin sensitivity and type 2 diabetes. We hypothesised that these variants may be associated with childhood obesity.

METHODS

Height and weight were recorded for 2454 prepubertal children aged between 4 and 10 years, who were then genotyped for three common variants of the PPARG locus: C-681G, Pro12Ala and C1431T.

RESULTS

No single variant of PPARG was significantly associated with height, weight or BMI. However, when modelling the variants together we detected an opposing interaction between the -681G and the Ala12 variants in height and weight, but not BMI (p=0.018, 0.013 and 0.119 respectively). The data were consistent with the Ala12 carriers being deficient in energy storage/utilisation, leading to reduced growth. In contrast, the -681G variant, which has been associated with increased adult height, was associated with accelerated growth. The two variants were in strong linkage disequilibrium. However, rare individuals bearing the isolated variants demonstrated the greatest variation from the mean, the most contrasting genotypes being associated with a variation of 7 kg in weight and 6 cm in height, standardised to 7.4-year-olds (p=0.006 and p=0.02 respectively).

CONCLUSIONS/INTERPRETATION

This study demonstrates that quantitative trait analysis of energy balance/growth and the PPARG locus is complex and requires the use of multiple genetic markers.