Abstract: FR-PO335

Disruption of Genome Maintenance Mechanisms in Renal Proximal Tubular Epithelial Cells Exacerbates Human Kidney Fibrosis

Session Information

Category: Chronic Kidney Disease (Non-Dialysis)

  • 308 CKD: Mechanisms of Tubulointerstitial Fibrosis

Authors

  • Kishi, Seiji, Tokushima University Hospital, TOKUSHIMA, TOKUSHIMA, Japan
  • Nishimura, Kenji, Tokushima University Hospital, TOKUSHIMA, TOKUSHIMA, Japan
  • Morizane, Ryuji, Brigham & Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States
  • Ichimura, Takaharu, Brigham & Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States
  • Bonventre, Joseph V., Brigham & Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States
  • Doi, Toshio, Tokushima University Hospital, TOKUSHIMA, TOKUSHIMA, Japan
Background

Renal proximal tubular epithelial cells (RPTECs) comprise the bulk of the renal parenchyma and are the primary target of a variety of insults to the kidney. While DNA damage and activation of the DNA damage response (DDR) play an important role in human disease, the role of DDR in the progression of human kidney disease remains unresolved. To investigate this mechanism, we evaluated the role of ataxia telangiectasia and Rad3-related (ATR) which is the key upstream regulator of cellular response to DNA damage.

Methods

We analyzed human kidney tissue from native kidney biopsy performed at Tokushima University Hospital. Of the 20 cases, 11 cases were kidneys with interstitial fibrosis and elevated serum creatinine, as well as 9 cases were with a pathologic diagnosis of minor glomerular abnormalities with normal serum creatinine and good preservation of tubules. An Active form of ATR (pATR) and the marker of DNA damage (γH2AX) were stained with KIM-1 to evaluate whether DDR correlates with eGFR or fibrosis.
In vitro study, to examine whether the inhibition of the ATR affects the survival of a proximal tubular epithelial cell line (HKC-8) after toxic insult, we assessed the degree of DNA damage and cell viability with or without the ATR inhibitor; VE-821.

Results

In kidney tissue from humans with CKD, ATR was activated in chronically injured RPTECs. The number of pATR and KIM-1 double positive tubules was inversely correlated with eGFR and positively correlated with the degree of kidney fibrosis. The number of γH2AX and KIM-1 double positive tubules in each kidney section was markedly increased, inversely correlated with eGFR and positively correlated with the degree of kidney fibrosis. We found an inverse correlation between γH2AX/KIM-1 positive and pATR/KIM-1 positive cells in CKD kidney. DNA damage and decline of cell viability of HKC-8 cells were further exacerbated when exposed to cisplatin, aristolochic acid or hypoxia in the presence of VE-821. Furthermore, ATR inhibition upregulated p21 and CTGF expression in HKC-8 cells after aristolochic acid treatment.

Conclusion

We demonstrate that DDR is seen in human kidney disease and ATR plays a protective role against tubular cell injury, death and fibrotic response. Regulation of ATR may be a therapeutic target against human kidney disease.

Funding

  • Government Support - Non-U.S.