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Abstract: TH-PO227

Role of Cellular Senescence and Epigenetic Drift in Interstitial Fibrosis of Diabetic Kidney Disease

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Tsukagoshi, Ayano, Chiba Daigaku Daigakuin Igaku Kenkyuin Igakubu, Chiba, Chiba, Japan
  • Maezawa, Yoshiro, Chiba Daigaku Daigakuin Igaku Kenkyuin Igakubu, Chiba, Chiba, Japan
  • Kaneko, Hiyori, Chiba Daigaku Daigakuin Igaku Kenkyuin Igakubu, Chiba, Chiba, Japan
  • Ide, Shintaro, Chiba Daigaku Daigakuin Igaku Kenkyuin Igakubu, Chiba, Chiba, Japan
  • Koshizaka, Masaya, Chiba Daigaku Daigakuin Igaku Kenkyuin Igakubu, Chiba, Chiba, Japan
  • Yokote, Koutaro, Chiba Daigaku Daigakuin Igaku Kenkyuin Igakubu, Chiba, Chiba, Japan
Background

In recent years, the number of elderly patients with diabetes has been increasing. In diabetic kidney disease, accumulation of senescent cells and senescence-related epigenome changes may contribute to renal fibrosis.

Methods

We investigated senescence markers, histone and its methylation in human renal fibroblasts (HKF) after replicative senescence. In addition, we created elderly diabetes model using streptozotocin injection to 108-week-old mice, and evaluated the phenotypes.

Results

HKF was mitotically arrested at passage 18 (p18). P18 HKF showed characteristics of cellular senescence including positive staining for senescence-associated βGal (SAβ-Gal), elevated expressions of CDKN2A, CDKN1A and IL6, one of the senescence-associated secretory phenotype (SASP). RNA-seq and pathway analysis revealed that senescent HKFs were associated with “SASP-related pathway” and “epigenetic gene regulation”. Interestingly, gene expression of histone methyltransferases such as EHMT2, EZH2, PRMT1 and SUV39H2 were decreased by 41%, 43%, 29% and 59%, respectively in p18 HKF compared to p12. In addition, by western blot, senescent HKFs showed a marked decrease of HistoneH3 and a concomitant loss of H3K9me3 and H3K27me3, suggesting the HKFs are undergoing the epigenetic drift. The kidneys of aged mice showed enlarged Masson’s Trichrome-positive area (18.6% at 18 weeks vs. 34.3% at 120 weeks of age), irregular vascular structure, and increased number of PDGFRβ-positive cells, indicating fibrosis. These findings were worsened in aged mice with STZ diabetes. Tubules, podocytes and some interstitial cells in aged mice were positive for SAβ-Gal and P16 staining. When examined by Nephroseq database, EHMT2 expression was significantly decreased in the tubule-interstitial region of human diabetic kidney disease. In addition, Camptothecin-induced senescence in HKF resulted in decreased extracellular matrix expressions such as Acta2, Col1a1 and FN1 after Tgfβ stimulation, suggesting that senescent kidney fibroblasts are responsible for inflammation, but they do not contribute to matrix production.

Conclusion

Senescent fibroblast with decreased histone methylation may provide increased SASP production, promote chronic inflammation and renal fibrosis.