Abstract: TH-PO080
Kidney Proximal Tubular TLR9 Exacerbates Ischemic AKI
Session Information
- AKI: Inflammation, New Technologies, Omics
October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Authors
- Han, Sang Jun, Columbia University Medical Center, New York, New York, United States
- Kim, Mihwa, Columbia University, New York, New York, United States
- Lee, H. Thomas, Department of Anesthesiology, New York, New York, United States
Background
Ischemic acute kidney injury (AKI) is a major clinical problem. Although Toll-like receptor 9 (TLR9) mediates cell death and inflammation in the liver, the role for kidney TLR9 in ischemic AKI is unknown. Here, we tested the hypothesis that renal proximal tubular TLR9 activation exacerbates ischemic AKI by promoting renal tubular apoptosis and inflammation.
Methods
Wild type mice (WT, TLR9fl/fl) or renal proximal tubular TLR9 null mice (TLR9fl/fl PEPCK Cre) were subjected to sham surgery or 30min kidney ischemia/reperfusion (IR) injury. A separate cohort of mice was pretreated with a selective TLR9 agonist (1mg/kg ODN-1668) or control ODN and subjected to 20min renal IR injury. Cultured mouse proximal tubule cells or immortalized human proximal tubule (HK-2) cells were treated with a selective TLR9 agonist (1-5 µM ODN-BW006) to determine whether TLR9 activation induces renal proximal tubular pro-inflammatory cytokines and NFκB activation in vitro.
Results
Renal proximal tubular TLR9 null mice were protected against renal IR injury with decreased plasma creatinine (1.8±0.2mg/dL), NGAL mRNA (362.6±61.6 fold increase over sham), neutrophil infiltration and TUNEL positive cells compared to WT mice (Cr=2.6±0.1mg/dL, NGAL=667.6±122.3 fold increase over sham, N=8 for all groups). In addition, renal proximal tubular TLR9 deletion reduced pro-inflammatory cytokine synthesis, caspase 3 and 8 activation when compared to WT mice after renal IR injury. Consistent with this, a selective TLR9 agonist exacerbated renal IR injury in WT mice (Cr=1.4±0.1mg/dL, 0.93±0.04mg/dL of vehicle) but not in renal proximal tubular TLR9 null mice (Cr=0.7±0.02mg/dL, 0.73±0.02mg/dL of vehicle, N=5 for all groups). In HK-2 cells, a TLR9 selective ligand induced NFκB activation, pro-inflammatory cytokine mRNA synthesis as well as caspase 3 and 8 activation. In primary cultures of mouse proximal tubule cells from TLR9fl/fl PEPCK Cre mice, TLR9 selective ligand induced significantly less pro-inflammatory cytokine mRNA synthesis compared to cells from WT mice.
Conclusion
Taken together, our studies suggest that renal proximal tubular TLR9 activation exacerbates ischemic AKI by promoting renal tubular inflammation and apoptosis after IR via NFκB, caspase 3, and 8 activation. Our studies provide novel insight to the pathophysiology of kidney proximal tubule TLR9 in ischemic AKI, suggesting a potential therapy for ischemic AKI.