The PPARγ2 Pro12Ala variant is protective against progression of nephropathy in people with type 2 diabetes

The role of the PPARG (Pro12Ala) common genetic variant on type 2 diabetes mellitus risk

Background

Type 2 diabetes (T2DM) prevalence has been rapidly increasing in the last decades. T2DM pathogenesis is related to insulin resistance and beta-cell dysfunction. Peroxisome proliferator-activated receptor gamma (PPARG) is concerned about T2DM risk through the involvement in adipocyte differentiation and energy homeostasis. The present study aimed to find the risk associated with a common genetic variant (Pro12Ala) of the PPARG gene in the development of T2DM in a group of the Iranian population.

Methods

Totally, 149 patients with T2DM and 96 healthy individuals were recruited in this case-control study. The genotyping of the genetic variant was carried out using the polymerase chain reaction (PCR) followed by Sanger sequencing.

Results

No significant difference is observed between the CG and GG genotypes frequency of the PPARG variant (P = 0.17) in T2DM patient and the control groups. Furthermore, the frequency of the G allele was similar between case and control groups. The Pro12Ala variant may decrease the risk of diabetic retinopathy (DR) which was not statistically significant. Furthermore, the Pro12Ala variant caused a 27% increase in the risk of diabetes nephropathy (DN) among patients with T2DM but was not significant.

Conclusions

Our findings showed that the PPARG variant could not impact on T2DM development and its complications.

Role of TCF7L2 and PPARG2 Gene Polymorphisms in Renal and Cardiovascular Complications among Patients with Type 2 Diabetes: A Cohort Study

BACKGROUND

The emerging renal and cardiovascular complications of type 2 diabetes (T2DM) genetics involves differently assembled gene variants including transcription factor 7-like 2 (TCF7L2) and peroxisome proliferator-activated receptor gamma 2 (PPARG2) polymorphisms. However, the relevance of these genes for complication prediction has not been extensively tested.

METHODS

We analyzed the SNP rs7903146 variants in TCF7L2 and PPARG2 gene polymorphisms for their contribution to the incidence of chronic kidney disease (CKD) and cardiovascular complications in a prospective cohort study. All T2DM patients were followed up to estimate the glomerular filtration rate and cardiovascular outcomes. Cox proportional hazards regression models were used to estimate the genotype effect on the incidence of CKD and vascular complications.

RESULTS

A total of 422 patients were included. SNP rs7903146 variants in the TCF7L2 gene were classified into 3 groups: CC, 385 patients (91.2%), CT, 32 patients (7.6%), and TT, 5 patients (1.2%), while in the PPARG2 gene they were classified into 2 groups: Pro12Pro, 404 patients (95.7%) and Pro12Ala, 18 patients (4.3%). The prevalence of CKD, cardiovascular disease, and death at the end of the 5-year follow-up was 16.8, 29, and 7.9%, respectively. The Pro12Ala variant of the PPARG2 gene was significantly associated with increased CKD risk at the end of the study (adjusted HR 3.45, 95% CI 1.01-11.77, p = 0.046); it showed a significant association with increased cerebrovascular risk, but not cardiovascular disease and mortality. No genotype effect of rs7903146 in the TCF7L2 gene was apparent on renal and cardiovascular complications, except the TT variant of rs7903146 increased cardiovascular events when compared with the non-TT variant.

CONCLUSION

The findings of our study were that the Pro12Ala variant in the PPARG2 gene was associated with risk of developing CKD and cerebrovascular disease in Asian T2DM subjects in a prospective cohort study. The TCF7L2 polymorphism was not associated with cardiovascular outcomes.

Nitrolipids in kidney physiology and disease

The kidneys are vital organs responsible for maintaining body fluid homeostasis within proper physiologic ranges. Kidney disease is an epidemic clinical problem causing significant morbidity and mortality, and current treatments are limited to renin-angiotensin system blockade or renal replacement therapy for the majority of affected individuals. There is a critical, unmet need for novel pharmacological agents to improve the outcome of patients with kidney disease. Nitro-oleic acid (NO2-OA) is an endogenously generated electrophilic compound with the capacity to modify thiols in proteins, altering their function. The most important targets appear to be the Keap1/Nrf2 and NF-κB pathways, which have widespread effects on antioxidant, detoxifying, and inflammatory responses in cells and tissues. Through these and potentially additional protective actions, NO2-OA may be capable of preserving or enhancing kidney function in acute and chronic kidney diseases.

Relationship between renal function and periodontal disease in community-dwelling elderly women with different genotypes

OBJECTIVES

The aim of this study was to examine the association between periodontal disease and renal function in elderly women with different genotypes.

MATERIAL AND METHODS

A total of 332 postmenopausal never-smoking women were analysed. Poor renal function was defined as serum cystatin C > 0.91 mg/l. Periodontal disease markers such as periodontal inflamed surface area (PISA) were evaluated. Selected variables, including PISA quartile, body mass index (BMI), HbA1C and age in Arg allele carriers and non-carriers based on the beta-3 adrenergic receptor, or between Ala allele carriers and non-carriers based on peroxisome proliferator-activated receptor gamma, were analysed using multiple logistic regression analysis.

RESULTS

The odds ratios of serum cystatin C level and PISA (fourth quartile) were significantly positive for both Arg (2.52; p = 0.035) and Ala allele non-carriers (2.36; p = 0.021). A significant association was also found between serum cystatin C level and BMI for both Arg (1.18; p = 0.001) and Ala allele non-carriers (1.12; p = 0.003).

CONCLUSION

The results of this study suggest that periodontal inflammation might be associated with renal function. Furthermore, in both the Arg and Ala allele non-carriers, the associations between BMI and PISA for renal function became stronger.

ISN Forefronts Symposium 2015: Nuclear Receptors and Diabetic Nephropathy

Diabetic nephropathy (DN) is the major reason for end stage renal disease in the western world. Patients with DN developed more severe cardiovascular complications with worse prognosis. In spite of tight blood pressure and glucose control through applying angiotensin II receptor antagonism, angiotensin receptor inhibitors and even direct renin inhibitors, the progression and development of DN has continued to accelerate. Nuclear receptors are, with few exceptions, ligand-depended transcription factors some of which modulate genes involved in the transportation and metabolism of carbohydrate or lipid, and inflammation. Considering the diverse biological functions of nuclear receptors, efforts have been made to explore their contributions to the pathogenesis of DN and potential therapeutic strategies. This review is mainly focused on the association between various nuclear receptors and the pathogenesis of DN, the potential beneficial effects of targeting these receptors for preventing the progress of DN, and the important role that nuclear receptors may play in future therapeutic strategies for DN.

Network biology concepts in complex disease comorbidities

The co-occurrence of diseases can inform the underlying network biology of shared and multifunctional genes and pathways. In addition, comorbidities help to elucidate the effects of external exposures, such as diet, lifestyle and patient care. With worldwide health transaction data now often being collected electronically, disease co-occurrences are starting to be quantitatively characterized. Linking network dynamics to the real-life, non-ideal patient in whom diseases co-occur and interact provides a valuable basis for generating hypotheses on molecular disease mechanisms, and provides knowledge that can facilitate drug repurposing and the development of targeted therapeutic strategies.

Nephroprotection by Hypoglycemic Agents: Do We Have Supporting Data?

Current therapy directed at delaying the progression of diabetic nephropathy includes intensive glycemic and optimal blood pressure control, renin angiotensin-aldosterone system blockade and multifactorial intervention. However, the renal protection provided by these therapeutic modalities is incomplete. There is a scarcity of studies analysing the nephroprotective effect of antihyperglycaemic drugs beyond their glucose lowering effect and improved glycaemic control on the prevention and progression of diabetic nephropathy. This article analyzes the exisiting data about older and newer drugs as well as the mechanisms associated with hypoglycemic drugs, apart from their well known blood glucose lowering effect, in the prevention and progression of diabetic nephropathy. Most of them have been tested in humans, but with varying degrees of success. Although experimental data about most of antihyperglycemic drugs has shown a beneficial effect in kidney parameters, there is a lack of clinical trials that clearly prove these beneficial effects. The key question, however, is whether antihyperglycemic drugs are able to improve renal end-points beyond their antihyperglycemic effect. Existing experimental data are post hoc studies from clinical trials, and supportive of the potential renal-protective role of some of them, especially in the cases of dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors. Dedicated and adequately powered renal trials with renal outcomes are neccessary to assess the nephrotection of antihyperglycaemic drugs beyond the control of hyperglycaemia.