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Abstract: FR-OR50

Impact of Caspase-1 Deletion on Apoptosis and AKI in a Murine Transplant Model

Session Information

Category: Transplantation

  • 1901 Transplantation: Basic

Authors

  • Jain, Swati, University of Colorado, Denver, Colorado, United States
  • Plenter, Robert J., University of Colorado, Denver, Colorado, United States
  • Nydam, Trevor, University of Colorado, Denver, Colorado, United States
  • Jani, Alkesh, University of Colorado, Denver, Colorado, United States
Background

Prolonged cold ischemia (CI) is a known risk factor for acute kidney injury (AKI) after kidney transplantation. However, the mechanism by which CI leads to AKI is unknown. Caspase-1 knockout mice (Casp1KO) are protected from AKI after warm ischemia/reperfusion injury. We hypothesized that Casp1KO mice would be protected from AKI following transplant.

Methods

Renal tubular cells (RTECs) were subjected to cold storage and rewarming (CS/REW). C57Bl/6J wild type or Casp1KO kidneys were subjected to CI for 30 min and then transplanted into wild type recipients (CI+Txp). The recipients underwent bilateral native nephrectomy at the time of transplant. Serum creatinine (sCr) was measured 24hrs after native nephrectomy to assess transplant function.

Results

In vitro: We observed significantly increased expression of NLRP1 inflammasome protein and Caspase-1 in cells subjected to CS/REW. Using Imagestream flow cytometer we observed spatial overlap between two different fluorescent labels of Caspase-1 and NLRP1 in RTECs exposed to CS/REW compared to control cells. In vivo studies: Wild-type kidneys subjected to CI+Txp demonstrated significantly increased Caspase-1 and NLRP1 protein expression. Caspase-1 deletion results in significantly decreased RTEC apoptosis in transplanted Casp1KO vs WT kidneys. Renal function, brush border injury, cast formation, tubular simplification were similar in both groups and not significantly different [Table 1].

Conclusion

CS/REW and CI+Txp increase NLRP1 and Caspase-1 expression and co-localization. Deletion of Caspase-1 improves tubular cell apoptosis following CI+Txp. However, Caspase-1 deletion did not prevent AKI and necrosis in kidneys subjected to CI+Txp, suggesting that other triggers of inflammation and programmed necrosis may need to be inhibited in addition to deletion of Caspase-1 to fully prevent AKI after kidney transplant.

Histological assessment of transplanted kidneys
 WT-WTCasp1KO-WT
Apoptotic cell death6.78 ± 1.214.13 ± 0.75 ***
Brush border injury (BBI)2.67 ± 0.302.59 ± 0.20
% of tubule displaying BBI79.11 ± 8.9993.15 ± 3.61
Tubular injury0.95 ± 0.210.93 ± 0.24
Casts0.59 ± 0.160.53 ± 0.20
Serum Creatnine1.58 ± 0.440.53 ± 0.20

***p<0.001 vs. WT-WT

Funding

  • Veterans Affairs Support