Background and Aim: The PI3 kinase-Akt-Gsk3 pathway is involved in both immune regulation and hepatocyte proliferation/death in inflammatory liver diseases. PTEN is a negative regulator of this pathway ubiquitous expressed in all types of liver cells. This study explored its potential roles, specifically, in liver immune response against IR
Methods: By crossing PTEN-LoxP with Lyz-Cre mice, we created none, single and double allele PTEN KO mice to study quantitatively functions of PTEN in bone marrow-derived macrophages (BMMs) in vitro and liver immune responses against IR in vivo in a murine model of liver partial warm ischemia and reperfusion. Inflammatory gene induction profiles were determined by qRT-PCR or ELISA; intracellular signaling activation by Western blots.
Results: Cell type specific PTEN deletion was confirmed by Western blot analysis of its expressions in hepatocytes, but not BMMs. Liver IRI was significantly alleviated only in PTEN double, but not single, allele KO mice [Figure 1], indicating that a complete inhibition PTEN activities was required for its therapeutic benefit.
Analysis of liver pro-inflammatory gene expressions showed that PTEN deletion led to a reduced inflammatory immune response against IR in livers. Levels of TNF-a, IL-1b and IL-6 gene transcripts were significantly lower in PTEN (-/-) mice than in PTEN (+/-) or (+/+) mice. In vitro, TLR4- and TLR9-mediated activation of BMMs were selectively inhibited in their pro-inflammatory gene productions (TNF-a, IL-12), while anti-inflammatory IL-10 gene production was sustained. To determine whether activation of the PI3 kinase pathway was responsible for the immune regulatory effect of PTEN deletion, Wortmannin (inhibitor of PI3 kinase) was used in BMM cultures and it did significantly increased TNF-a productions from PTEN (-/-) cells in response to TLR ligands.
Conclusion: Our results revealed that PTEN promoted liver pro-inflammatory immune response against IR by regulating macrophage activations by TLRs.
To cite this abstract in AMA style:Shi Y, Rao J, Shen X, Gao F, Busuttil R, Kupiec-Weglinski J, Zhai Y. Phosphatase and Tensin Homolog (PTEN) Promotes Liver Pro-Inflammatory Immune Response Against Ischemia Reperfusion Injury (IRI) [abstract]. Am J Transplant. 2013; 13 (suppl 5). https://atcmeetingabstracts.com/abstract/phosphatase-and-tensin-homolog-pten-promotes-liver-pro-inflammatory-immune-response-against-ischemia-reperfusion-injury-iri/. Accessed June 5, 2020.
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