GILZ Modulates the Recruitment of Monocytes/Macrophages Endowed with a Resolving Phenotype and Favors Resolution of...

Macrophages are important effectors of inflammation resolution that contribute to the elimination of pathogens and apoptotic cells and restoration of homeostasis. Pre-clinical studies have evidenced the anti-inflammatory and pro-resolving actions of GILZ (glucocorticoid-induced leucine zipper). Here, we evaluated the role of GILZ on the migration of mononuclear cells under nonphlogistic conditions and Escherichia coli-evoked peritonitis. TAT-GILZ (a cell-permeable GILZ-fusion protein) injection into the pleural cavity of mice induced monocyte/macrophage influx alongside increased CCL2, IL-10 and TGF-β levels. TAT-GILZ-recruited macrophages showed a regulatory phenotype, exhibiting increased expression of CD206 and YM1. During the resolving phase of E. coli-induced peritonitis, marked by an increased recruitment of mononuclear cells, lower numbers of these cells and CCL2 levels were found in the peritoneal cavity of GILZ-deficient mice (GILZ^-/-) when compared to WT. In addition, GILZ^-/- showed higher bacterial loads, lower apoptosis/efferocytosis counts and a lower number of macrophages with pro-resolving phenotypes. TAT-GILZ accelerated resolution of E. coli-evoked neutrophilic inflammation, which was associated with increased peritoneal numbers of monocytes/macrophages, enhanced apoptosis/efferocytosis counts and bacterial clearance through phagocytosis. Taken together, we provided evidence that GILZ modulates macrophage migration with a regulatory phenotype, inducing bacterial clearance and accelerating the resolution of peritonitis induced by E. coli.