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Abstract: SA-PO579

Inhibition of BRD4 with MS417 Lessens the Inflammatory Response Following Ischemia Reperfusion Injury

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Reid, Shelby, Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
  • Zhou, Xiaohua, University of Toronto, Toronto, Ontario, Canada
  • John, Rohan, University Health Network, Toronto, Ontario, Canada
  • Scholey, James W., University of Toronto, Toronto, Ontario, Canada
Background

A key regulator of the immune and inflammatory response is the NFκB//Rel protein family. A variety of stimuli, including ischemia reperfusion injury (IRI), activate the NFκB signalling cascade which stimulates the transcription of genes primarily involved in immune and inflammatory response. A key regulator of NFκB transcription is BRD4 which binds to acetylated RelA leading to the recruitment and activation of CDK9, subsequently resulting in the phosphorylation of RNA polymerase II and the transcriptional activation of NFκB target genes. The key role of BRD4 in transcription has led to the development of small molecule inhibitors that competitively bind to the acetylated RelA. One inhibitor, MS417, has shown promise in attenuating injury in different models of kidney injury, but has yet to be analyzed in a model of ischemia reperfusion injury.

Methods

Male C57BL/6 mice were treated with 1 μM of MS417 or vehicle via oral gavage daily for 7 days before unilateral IR was performed by clamping off the renal artery for 45 minutes followed by reperfusion. Daily treatment was continued until the time of sacrifice when tissue was collected for immunohistochemistry (IHC) and PCR analysis. Fixed kidney tissue was paraffin-embedded, sectioned, stained with periodic acid–Schiff (PAS) and scored for glomerular injury as well as for infiltrating neutrophils in a blinded manner. RNA was extracted from snap-frozen kidney tissue and was reverse transcribed into cDNA which was subsequently used in quantitative polymerase chain reaction.

Results

IHC staining for tubular injury and neutrophil infiltration showed a marked increase in the control group (treatment with saline) when compared to shams (no IRI). Treatment with MS417 prior to IR resulted in a lower trend in both injury and neutrophil infiltration. Administration of MS417 further suppressed the increase of the transcript levels of the proinflammatory markers C-C Motif Chemokine Ligand 2, Interleukin-1β, and Interleukin-6 by approximately 50%.

Conclusion

Treatment with the BRD4 inhibitor, MS414, prior to IR resulted in reduced tubular injury and neutrophil recruitment as well as reduced expression of proinflammatory genes. Further analysis of MS417’s specificity and role in lessening the inflammatory response following IR is required.