Association between PNPLA2 Gene Polymorphisms and the Risk of Diabetic Kidney Disease in a Chinese Han Population with Type 2 Diabetes

Unbiased gene expression analysis of the delayed fracture healing observed in Zucker diabetic fatty rats

Aims

Impaired fracture repair in patients with type 2 diabetes mellitus (T2DM) is not fully understood. In this study, we aimed to characterize the local changes in gene expression (GE) associated with diabetic fracture. We used an unbiased approach to compare GE in the fracture callus of Zucker diabetic fatty (ZDF) rats relative to wild-type (WT) littermates at three weeks following femoral osteotomy.

Methods

Zucker rats, WT and homozygous for leptin receptor mutation (ZDF), were fed a moderately high-fat diet to induce T2DM only in the ZDF animals. At ten weeks of age, open femoral fractures were simulated using a unilateral osteotomy stabilized with an external fixator. At three weeks post-surgery, the fractured femur from each animal was retrieved for analysis. Callus formation and the extent of healing were assessed by radiograph and histology. Bone tissue was processed for total RNA extraction and messenger RNA (mRNA) sequencing (mRNA-Seq).

Results

Radiographs and histology demonstrated impaired fracture healing in ZDF rats with incomplete bony bridge formation and an influx of intramedullary inflammatory tissue. In comparison, near-complete bridging between cortices was observed in Sham WT animals. Of 13,160 genes, mRNA-Seq analysis identified 13 that were differentially expressed in ZDF rat callus, using a false discovery rate (FDR) threshold of 10%. Seven genes were upregulated with high confidence (FDR = 0.05) in ZDF fracture callus, most with known roles in inflammation.

Conclusion

These findings suggest that elevated or prolonged inflammation contributes to delayed fracture healing in T2DM. The identified genes may be used as biomarkers to monitor and treat delayed fracture healing in diabetic patients.

Xanthine-derived reactive oxygen species exacerbates adipose tissue disorders in male db/db mice induced by real-ambient PM2.5 exposure

Epidemiological and experimental data have associated exposure to fine particulate matter (PM2.5) with various metabolic dysfunctions and diseases, including overweight and type 2 diabetes. Adipose tissue is an energy pool for storing lipids, a necessary regulator of glucose homeostasis, and an active endocrine organ, playing an essential role in developing various related diseases such as diabetes and obesity. However, the molecular mechanisms underlying PM2.5-impaired functions in adipose tissue have rarely been explored. In this work, metabolomics based on liquid chromatography-mass spectrometry was performed to study the adverse impacts of PM2.5 exposure on brown adipose tissue (BAT) and white adipose tissue (WAT) in the diabetic mouse model. We found the effects of PM2.5 exposure by comparing the different metabolites in both adipose tissues of male db/db mice using real-ambient PM2.5 exposure. The results showed that PM2.5 exposure changed the purine metabolism in mice, especially the dramatic increase of xanthine content in both WAT and BAT. These changes led to significant oxidative stress. Then the results from real-time quantitative polymerase chain reaction showed that PM2.5 exposure could cause the production of inflammatory factors in both adipose tissues. Moreover, the increased reactive oxygen species (ROS) promoted triglyceride accumulation in WAT and inhibited its decomposition, causing increased WAT content in db/db mice. In addition, PM2.5 exposure significantly suppressed thermogenesis and affected energy metabolism in the BAT of male db/db mice, which may deteriorate insulin sensitivity and blood glucose regulation. This research demonstrated the impact of PM2.5 on the adipose tissue of male db/db mice, which may be necessary for public health.

Single nucleotide polymorphisms in the GFR-related gene and the SNP-SNP interactions on the risk of diabetic kidney disease in Chinese Han population

PURPOSE

Genetic susceptibility is an important pathogenic mechanism in diabetic kidney disease (DKD). However, the specific gene variant associated with DKD susceptibility remains unclear. Glomerular filtration rate (GFR), an important indicator for the process of DKD, has a heritable component. This study aimed to explore whether these GFR-related single nucleotide polymorphisms (SNPs) were associated with DKD.

METHODS

GFR-related SNPs were collected from the Phenotype-Genotype Integrator (PheGenI) database. SNPs for population cohort analysis were selected following the criteria of complete records of eQTL and MAF > 5% in the Chinese Han population. Totally 498 subjects participated, including166 patients with DKD, 166 patients with T2DM, and 166 controls. The genotypes of SNPs were determined using a Sequenom MassARRAY system. Plink software was employed to analyze the SNP-SNP interactions.

RESULTS

By screening the GFR-related SNPs recorded in the PheGenI database, four SNPs (rs1260326, rs17319721, rs35716097, and rs6420094) were finally selected to investigate the association with DKD. It was shown that one of the four SNPs was related to DKD. The G allele of SLC34A1 rs6420094 was associated with a decreased risk of DKD in DKD and T2DM groups (OR 0.716; P = 0.049). Genetic model analysis revealed that rs6420094 was a protective factor for DKD in T2DM in a dominant model and an additive model (P = 0.03; P = 0.032, respectively). Although rs17319721 was not associated with the risk of DKD, the SNP-SNP interactions between rs17319721 and rs6420094 predicted a significantly decreased risk of DKD (OR 0.464; P = 0.047).

CONCLUSION

SLC34A1 rs6420094 was associated with a decreased DKD risk in the Chinese Han population. SNP-SNP interaction between rs17319721 and rs6420094 was associated with a lower risk of DKD.