The on-off action of Forkhead protein O3a in endotoxin tolerance of Kupffer cells depends on the PI3K/AKT pathway

Di Mu; Chunmu Miao; Yao Cheng; Peizhi Li; Jianping Gong; Wenfeng Zhang

doi:10.1016/j.intimp.2020.106342

The on-off action of Forkhead protein O3a in endotoxin tolerance of Kupffer cells depends on the PI3K/AKT pathway

Int Immunopharmacol. 2020 Mar 3:82:106342. doi: 10.1016/j.intimp.2020.106342. Online ahead of print.

Authors

Di Mu¹, Chunmu Miao², Yao Cheng², Peizhi Li², Jianping Gong², Wenfeng Zhang³

Affiliations

¹ Key Laboratory of Laboratory Medical Diagnostics, Chinese Ministry of Education, Chongqing Medical University, Chongqing 400016, China.
² Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China.
³ Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China. Electronic address: zhangwenfeng@cqmu.edu.cn.

PMID: 32143003
DOI: 10.1016/j.intimp.2020.106342

Abstract

Background: The endotoxin tolerance (ET) of Kupffer cells (KCs) is an important protective mechanism for limiting endotoxin shock. As a key anti-inflammatory molecule, the roles and mechanism of Forkhead protein O3a (Foxo3a) in ET of KCs are not yet well understood.

Methods: ET and nonendotoxin tolerance (NET) KCs models were established in vitro and in vivo. The levels of cytokines were detected by enzyme-linked immunosorbent assay (ELISA). The protein expression and phosphorylation levels were detected by western blotting (WB). Changes in the localization of nuclear factor kappa B (NF-κB) and Foxo3a in KCs were detected by immunofluorescence assays. KCs apoptosis and survival rates were detected by flow cytometry and an automatic cell counter, respectively.

Results: The activity of NF-κB and the levels of p-Foxo3a and tumor necrosis factor (TNF-α) in the ET group were significantly lower than those in the NET group, while the levels of Foxo3a and interleukin 10 (IL-10) in the ET group were significantly higher than those in the NET group. Overexpression of Foxo3a or the use of a phosphatidylinositol-3-hydroxykinase (PI3K) inhibitor suppressed the activation of NF-κB by decreasing the levels of p-Foxo3a by inhibiting the activity of PI3K/AKT, which improved the tolerance of KCs and mice to endotoxin. In contrast, silencing Foxo3a or the use of a PI3K agonist reduced the tolerance of KCs and mice to endotoxin. The PI3K agonist counteracted the inhibitory effects of Foxo3a overexpression on NF-κB, impairing the tolerance of KCs to endotoxin.

Conclusions: The on-off action of Foxo3a in the ET of KCs depends on the PI3K/AKT pathway.

Keywords: Endotoxin tolerance; Fork head protein O3a; Kupffer cells; Nuclear factor kappa B; Phosphatidylinositol-3-hydroxykinase.