S. J. Concors1,3, D. R. Murken1, D. D. Aufhauser1, Z. Wang1, G. Ge1, W. W. Hancock2,4, M. H. Levine1,3 1University Of Pennsylvania,Surgery,Philadelphia, PA, USA 2University Of Pennsylvania,Pathology And Laboratory Medicine,Philadelphia, PA, USA 3Children’s Hospital Of Philadelphia,Surgery,Philadelphia, PA, USA 4Children’s Hospital Of Philadelphia,Pathology And Laboratory Medicine,Philadelphia, PA, USA
Introduction: Ischemia/reperfusion injury (IRI) leads to significant morbidity and mortality in liver transplantation. Understanding the physiology of IRI is necessary to develop methods of prevention and treatment. Histone deacetylases (HDACs) regulate diverse cellular processes. We have previously shown protection from renal IRI with HDAC inhibition. We wished to investigate the effects of HDAC inhibition in liver IRI, and if this protective effect is translatable to other mechanisms of liver injury.
Methods: Male wild type C57BL/6 (WT) mice were treated with pan-HDAC inhibitor trichostain A (TSA), class I HDAC inhibitor MS-275, HDAC6 inhibitor Tubastatin-A (TubA), Hsp90 inhibitor 17AAG, or DMSO at 16 and 1 h pre-IRI. Whole-body HDAC-1, -2, -6, and -8 deficient and tamoxifen-treated WT male mice were also used. Mice were subjected to 70% liver ischemia for 60 min under strict temperature control. For the acetaminophen (APAP) toxicity experiment, WT mice were treated with DMSO or TubA at 16 h and again just prior to administration of a sublethal dose of APAP (500mg/kg). In both experiments, AST and ALT levels were assessed 24 hours after injury, as well as histopathologic examination and Suzuki liver injury scale scoring at 48 hours post injury.
Results: TSA- and TubA-treated mice developed significantly less hepatocellular injury after liver IRI than controls with significantly lower AST/ALT levels(Fig 1A); Tub-A developed significantly less liver injury on histopathology. H1-/- mice developed significantly less injury after IRI compared to controls, but HDAC6 gene deletion did not mitigate IRI (Fig 1B). TubA also mitigated APAP-induced liver injury (Fig 1C).
Conclusion:Pan-HDAC inhibition mitigates liver injury after IRI in mice. Selective inhibition of HDAC1 via inducible gene deletion and pharmacologic inhibition of HDAC6 both replicate this protection. These findings are distinct from the pattern of HDAC involvement in renal IRI and suggest tissue-specific roles for HDACs in IRI response. Pharmacologic inhibition of HDAC6 also mitigated APAP-induced hepatocellular injury suggesting that the protective effects of TubA are not injury-type specific.
