*Purpose: Glycogen synthase kinase 3β (Gsk3β) differentially regulates pro- and anti-inflammatory programs in macrophages upon TLR stimulations. We have documented in a murine liver partial warm ischemia model that both Gsk3 inhibition in WT mice and myeloid Gsk3β deficiency protected livers from IRI. As liver macrophages (MФs) are heterogenous in their origin and function and the outcome of liver IRI is dependent on not only inflammation activation, but also its resolution, we determined how Gsk3β regulated liver IRI in MФ-specific and disease stage-specific manner.

*Methods: We compared both liver inflammation activation (6-24h) and resolution (3-7d) between WT and myeloid Gsk3β deficient mice. KCs or CD11b+ MФs were selectively depleted by low-dose clodronate liposomes (CL, 1x 200ul, i.p.,-48h) or by diphtheria toxin (DT, 2×10μg/g, i.v.) in CD11b-DTR mice. WT or Gsk3β deficient KCs or bone marrow-derived MФs (BMMs) were used to reconstitute CL- or DT-treated hosts.

*Results: When KCs were depleted prior to the onset of liver ischemia, the protection of livers from IRI at 6h post reperfusion was abolished in Gsk3β deficient mice. However, livers still recovered from IRI significantly better in these mice, as compared with the WT counterparts. The hepatocellular damages were fully repaired, neutrophils were cleared and infiltrating MФs were reprogrammed to F4/80+CD11b- KC-like cells in IR livers of the Gsk3β deficient mice at day 7 post reperfusion, while these resolution processes were significantly delayed in WT controls until day 14. To further establish that Gsk3β deficiency in KCs were sufficient to protect livers from IRI, we reconstituted KC-depleted WT hosts (by CLs) with either WT or Gsk3β deficient KCs. Indeed, Gsk3β deficient KCs were much more potent to protect livers: sALT levels were significantly lower with much better preserved liver architectures; liver pro-inflammatory activation was also inhibited more significantly, at 6h post reperfusion. Mechanistically, Gsk3β deficient KCs were protected from necroptotic depletion by IR that significantly higher numbers of Clec4F+ KCs (by immune histochemical staining) were detected in IR livers of Gsk3β deficient vs. WT mice. In vitro analysis of KCs and BMMs revealed that Gsk3β deficiency did not enhance KC efferocytosis, but rather promoted IL-10/inhibited TNF-a induction upon TLR stimulation in both types of MФs. Importantly, Gsk3β deficiency facilitated the induction of Axl, MerTK and TIM-4 expressions in BMMs upon inflammatory stimulations, which were critical for their reparative functions.

*Conclusions: Gsk3β regulates distinctive MФ subsets at different stages of liver IRI. It promotes KC pro-inflammatory activation, while facilitates infiltrating MФ reprogramming into reparative type in the resolution of liver IRI.

« Back to 2021 American Transplant Congress