Background/Aim: Sirtuin1 (SIRT1), a NAD⁺-dependent type III histone/protein deacetylase, plays a key role in inflammation responses and stress resistance. Although SIRT1 may regulate innate activation in liver ischemia-reperfusion injury (IRI), the role of macrophage-specific SIRT1 in IR-stress remains elusive. Although tumor suppressor gene p53 may control macrophage activation/inflammation responses, crosstalk between SIRT1 and p53 at the macrophage level has not been studied. Here, we focused on mechanisms by which SIRT1/p19/p53 signaling regulates macrophage activation and inflammation.

Methods: Male C57BL/6 wild type (WT) mice underwent warm partial hepatic ischemia (90min); liver samples were harvested at 6h of reperfusion. Separate groups of mice were treated with SIRT1 activator (Resveratrol, Res; 25mg/kg ip) or vehicle (Vhc) at 1 h prior to ischemia insult. LPS-stimulated bone marrow-derived macrophage (BMM) cultures were set-up to dissect individual macrophage signaling pathways in vitro.

Results: Res treatment attenuated liver IRI in WT mice as compared to control (Con) or the Vhc group. (sALT: Con 12,749±3,988, Res 7,818±1,536, Vhc 13,617±2,024 IU/L; sAST: Con 14,440±2,585, Res 4,929±989, Vhc 12,890±2,088 IU/L; n=4-5, p<0.05). Western blot analysis showed increased protein levels of SIRT1, p19, p53, MDM2 and PUMA in Res-treated IR-stressed livers as compared to Con or Vhc groups, data confirmed by RT-PCR analyses. Liver IRI cytokine signature (MCP1, IL-1β, TNFα) was suppressed in the Res group (p<0.05). BMM cell cultures revealed that Res (100uM) selectively increased protein levels of SIRT1, p19, p53, MDM2, PUMA while downregulating p-Stat1, iNOS and p-IkBα. SIRT1 knock-down by siRNA produced opposite transcriptional signaling profile in BMM cultures. RT-PCR also showed that unlike SIRT1-siRNA, addition of Res to BMM increased SIRT1, Noxa, p21 and decreased MCP1, IL-1β, CCL-5, GzmB, CXCL-10 and iNOS. Moreover Res-mediated induction of p53, MDM2, PUMA, Noxa and p21 while suppressing iNOS, p-IkBα, IL-1β and CCL-5, were impaired by p19 knockdown. Knockdown of p53 by siRNA prevented Res from suppressing iNOS, p-IkBα, IL-1β and CCL-5.

Conclusion: Resveratrol regulates macrophage activation and suppresses inflammation through SIRT1/p19/p53 pathway, which in turn attenuates liver IRI.

CITATION INFORMATION: Nakamura K, Zhang M, Ke B, Kageyama S, Busuttil R, Araujo J, Kupiec-Weglinski J. Resveratrol Attenuates Liver IRI by Regulating Macrophage Activation Through SIRT1/p19/p53 Pathway. Am J Transplant. 2016;16 (suppl 3).

« Back to 2016 American Transplant Congress