Shp2 Deficiency Impairs the Inflammatory Response Against Haemophilus influenzae by Regulating Macrophage Polarization

Abstract

Macrophages can polarize and differentiate to regulate initiation, development, and cessation of inflammation during pulmonary infection with nontypeable Haemophilus influenzae (NTHi). However, the underlying molecular mechanisms driving macrophage phenotypic differentiation are largely unclear. Our study investigated the role of Shp2, a Src homology 2 domain-containing phosphatase, in the regulation of pulmonary inflammation and bacterial clearance. Shp2 levels were increased upon NTHi stimulation. Selective inhibition of Shp2 in mice led to an attenuated inflammatory response by skewing macrophages toward alternatively activated macrophage (M2) polarization. Upon pulmonary NTHi infection, Shp2(-/-) mice, in which the gene encoding Shp2 in monocytes/macrophages was deleted, showed an impaired inflammatory response and decreased antibacterial ability, compared with wild-type controls. In vitro data demonstrated that Shp2 regulated activated macrophage (M1) gene expression via activation of p65-nuclear factor-κB signaling, independent of p38 and extracellular regulated kinase-mitogen-activated proteins kinase signaling pathways. Taken together, our study indicates that Shp2 is required to orchestrate macrophage function and regulate host innate immunity against pulmonary bacterial infection.

Keywords: Haemophilus influenzae; inflammatory response; macrophage polarization; protein-tyrosine phosphatase Shp2.