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Abstract: FR-OR049

Aberrant DNA Methylation of mTOR Pathway Promotes Inflammatory Activation of Immune Cells in Diabetic Kidney Disease

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Chen, Guochun, The Second Xiangya Hospital, Changsha, China
  • Dong, Zheng, Medical College of Georgia, Augusta, United States
  • Sun, Lin, The Second Xiangya Hospital, Changsha, China
Background

DNA methylation has been implicated in the pathogenesis of diabetic kidney disease (DKD), but the underlying mechanism is unclear. We hypothesize that aberrant DNA methylation in peripheral immune cells may contribute to the inflammation and pathological progression in DKD.

Methods

Whole DNA samples were extracted from human peripheral blood mononuclear cells (PBMCs) and applied to genome-wide methylation analysis. PBMCs were isolated from human whole blood samples to determine the expressions of DNMTs and their relationship with the inflammatory activities. At 8 weeks of age, db/db mice were treated with 5-Aza or PBS twice a week for 12 weeks. Peripheral immune cells were isolated from donor db/db mice with or without 5-Aza treatments and intravenously infused to host diabetic animals. In in-vitro studies, human PBMCs and mouse splenocytes were isolated and applied to the intervention experiments of targeting DNMT1 or mTOR pathway.

Results

The key DNA methylation enzyme DNMT1 increased along with the inflammatory activity of PBMCs in DKD patients. Inhibition of DNMT1 with 5-Aza markedly increased CD4+CD25+ regulatory T (Treg) cells in the peripheral immune cells from DKD patients and in db/db diabetic animals, leading to enhanced immunosuppressive activity. In db/db mice, adoptive transfer of Treg cells from 5-Aza-treated animals beneficially modified the inflammatory phenotype of host immune system, resulting in significant improvement of diabetic albuminuria and chronic kidney injuries. We demonstrated differentially methylated genes in diabetic PBMCs, revealing prominent DNA hypomethylation in the upstream regulatory genes of mTOR pathway. Further mRNA array confirmed the induction of genes predominantly in the positive, rather than negative, regulators of mTOR pathway in DKD. In db/db mice, mTOR activity showed a correlation with the level of global DNA methylation and the inflammatory capacity of kidney immune cells. Finally, mTOR interventions efficiently modified the regulatory effects of 5-Aza on diabetic immune cells.

Conclusion

Chronic hyperglycemia induces aberrant DNA methylation of mTOR pathway, leading to pathogenic activation of immune cells in DKD progression. Our study highlights the therapeutic potentials of targeting epigenetic events in the immune system for treatment of chronic kidney disease and DKD in particular.