*Purpose: Although Ikaros is a well-established regulator of lymphopoiesis, its role in myeloid cells and organ IRI remains unclear. We recently reported that the SIRT1-mediated autophagy promotes hepatic rejuvenation in mouse and human liver transplantation (LT). It is currently unclear whether Ikaros, a regulator of AMPK signaling, and SIRT1 are involved in immune liver injury and metabolic homeostasis.

*Methods: To interrogate the significance of myeloid Ikaros-SIRT1 axis in the context of innate immune activation, we undertook comprehensive molecular/functional studies using in vitro bone marrow-derived macrophages (BMM) treated with siRNA to Ikaros, and in vivo mouse models utilizing liver warm IRI in WT, myeloid-specific SIRT1-KO, and CD11b-DTR mouse systems. In the clinical arm, retrospective analyses were performed on clinical hepatic biopsies (Bx) taken from human LT patients (n=55).

*Results: First, clinical LT Bx were divided into “high” and “low” groups, based on Ikaros levels (RT-PCR). The Ikaros “high” expression group showed significantly elevated sALT at POD1-4, in association with increased cleaved caspase1 (cCasp1) but lower SIRT1 protein levels in post-transplant Bx (p<0.05), as compared to Ikaros “low”-expression controls. Using flow-cytometry/immunofluorescence staining, we determined that the major source of Ikaros signaling in ischemia-stressed livers comes from recruited macrophages. Murine BMM assays were then used to assess Ikaros function in innate-immune activation. Ikaros silencing in BMM decreased LPS/ATP-induced cCasp1, cleaved Gasdermin D (cGSDMD) and mature IL1β in a SIRT1-dependent manner. When CD11b+ cells were depleted from IR-stressed CD11b-DTR hosts, livers showed suppressed Ikaros expression that could be reversed along with cCasp1 and cGSDMD levels, after adoptive transfer of normal BMM. Interestingly, IR-stressed livers in CD11b-deficient mice reconstituted with Ikaros-depleted BMM showed increased SIRT1, decreased cCasp1/cGSDMD and preservation of the hepatocellular function (n=6, p<0.05). Finally, mSIRT1-KO mice suffered from exacerbated hepatic IRI, accompanied by up-regulated cCasp1/cGSDMD (n=7, p<0.05).

*Conclusions: Our results identify the Ikaros – SIRT1 signaling axis as a novel regulator of the canonical inflammasome-pyroptosis pathway, with divergent innate phenotypic signatures in sterile inflammation response in liver transplantation.

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