miR-155 enhances apoptosis of macrophage through suppressing PI3K-AKT activation in Pseudomonas aeruginosa keratitis

Keratitis induced by <i>Pseudomonas aeruginosa</i> (<i>P</i>. <i>aeruginosa</i>) is an acute and serious corneal inflammation. As a family of gene regulators, miRNAs play a crucial role in modulating host response after microbial invasion. However, their functions in <i>P</i>. <i>aeruginosa</i> keratitis remain largely unclear. In the present study, we demonstrated that miR-155 expression was significantly increased in macrophages and corneal tissue after <i>P</i>. <i>aeruginosa</i> infection. <i>In vivo</i> studies demonstrated that mice with miR-155 knockdown displayed more resistance to <i>P. aeruginosa</i> keratitis, with a lower bacterial burden. In addition, <i>in vitro</i> and <i>in vivo</i> studies indicated that miR-155 enhanced apoptosis of macrophages after <i>P. aeruginosa</i> infection, and resulted in a susceptible phenotype of <i>P. aeruginosa</i> keratitis. Moreover, miR-155 induced apoptosis through reducing activation of PI3K-Akt signaling pathway. Our data provided evidence of miR-155 mediated apoptosis of macrophage in <i>P. aeruginosa</i> keratitis, which may be an underlying target for the therapy of <i>P. aeruginosa</i> keratitis and other infectious diseases.