SHIP-1 Regulates Phagocytosis and M2 Polarization Through the PI3K/Akt–STAT5–Trib1 Circuit in Pseudomonas aeruginosa Infection
Shugang Qin, Jiaxin Li, Chuan‐Min Zhou, Breanna Privratsky, Jacob Schettler, Xin Deng, Zhenwei Xia, Yong Zeng, Hong Wu, Min Wu
Abstract
SHIP-1 is an inositol phosphatase that hydrolyzes phosphatidylinositide 3-kinase (PI3K) products and negatively regulates protein kinase B (Akt) activity, thereby modulating a variety of cellular processes in mammals. However, the role of SHIP-1 in bacterial-induced sepsis is largely unknown. Here, we show that SHIP-1 regulates inflammatory responses during Gram-negative bacterium Pseudomonas aeruginosa infection. We found that infected-SHIP-1-/- mice exhibited decreased survival rates, increased inflammatory responses and susceptibility owing to elevated expression of PI3K compared to wild type (WT) mice. Inhibiting SHIP-1 via siRNA silencing resulted in lipid raft aggregates, aggravated oxidative damage and bacterial burden in macrophages after PAO1 infection. Mechanistically, SHIP-1 deficiency augmented phosphorylation of PI3K, and nuclear transcription of signal transducer and activator of transcription 5 (STAT5) to induce the expression of Trib1, which is critical for differentiation of M2 but not M1 macrophages. These findings reveal a previously unrecognized role of SHIP-1in inflammatory responses and macrophage homeostasis during P. aeruginosa infection through a PI3K/Akt-STAT5-Trib1 axis.