The ubiquitous
serine/threonine kinase glycogen synthase kinase 3 beta (Gsk3β) differentially regulates macrophage
Toll-like receptor (TLR)-triggered pro- and anti-inflammatory
cytokine programs. This study was designed to determine the in vivo role and therapeutic potential of Gsk3β modulation in tissue
inflammation and injury in a murine model of liver partial
warm ischemia/
reperfusion injury (IRI). As a constitutively activated liver
kinase, Gsk3β became quickly inactivated (phosphorylated) following IR. The active Gsk3β, however, was essential for the development of IRI pathology, as administration of its specific inhibitor,
SB216763, ameliorated the hepatocellular damage, evidenced by reduced serum
alanine aminotransferase (
sALT) levels and well-preserved liver architecture compared with controls. The liver protective effect of Gsk3β inhibition was dependent on an immune regulatory mechanism, rather than direct cytoprotection via mitochondria permeability transition pores (
MPTP). Indeed: (1) coadministration of
SB216763 and
atractyloside (
MPTP opener) failed to abrogate a local cytoprotective Gsk3β inhibition effect; (2)
SB216763 selectively inhibited IR-triggered liver pro-inflammatory, but spared
interleukin (IL)-10, gene induction programs; and (3)
IL-10 neutralization restored liver
inflammation and IRI in SB216763-treated mice. Gsk3β inactivation by IR was a self-regulatory mechanism in liver homeostasis, critically dependent on
phosphoinositide 3 (PI3)-kinase activation, as administration of a
PI3 kinase inhibitor,
wortmannin, reduced Gsk3 phosphorylation and augmented liver damage. In vitro,
IL-10 was critical for the suppression of pro-inflammatory gene programs by Gsk3 inhibition in bone marrow-derived macrophages in response to TLR4 stimulation.
CONCLUSION: Our novel findings document the key immune regulatory function of Gsk3β signaling in the pathophysiology of liver IRI, and provide a rationale to target Gsk3β as a refined therapeutic strategy to ameliorate liver IRI.