Angiotensin-(1-7)/MasR axis promotes migration of monocytes/macrophages with a regulatory phenotype to perform phagocytosis and efferocytosis

Abstract

Nonphlogistic migration of macrophages contributes to the clearance of pathogens and apoptotic cells: critical steps for the resolution of inflammation and return to homeostasis. Angiotensin-(1-7) [Ang-(1-7)] is an heptapeptide of the Renin-Angiotensin system that acts through Mas receptor (MasR). Ang-(1-7) has recently emerged as a novel pro-resolving mediator, yet Ang-(1-7) resolution mechanisms are not fully determined. Herein, Ang-(1-7) stimulated migration of human and murine monocytes/macrophages in a MasR, CCR2 and MEK/ERK1/2-dependent manner. Pleural injection of Ang-(1-7) promoted nonphlogistic mononuclear cell influx alongside increased levels of CCL2, IL-10 and macrophage polarization towards a regulatory phenotype. Ang-(1-7) induction of CCL2 and mononuclear cell migration was also dependent on MasR and MEK/ERK. Noteworthy, MasR was upregulated during resolution phase of inflammation and their pharmacological inhibition or genetic deficiency impaired mononuclear cell recruitment during self-resolving models of LPS pleurisy and E. coli peritonitis. Inhibition/absence of MasR was associated with reduced CCL2 levels, impaired phagocytosis of bacteria, efferocytosis and delayed resolution of inflammation. In summary, we have uncovered a novel pro-resolving feature of Ang-(1-7), namely the recruitment of mononuclear cells favoring efferocytosis, phagocytosis and resolution of inflammation. Mechanistically, cell migration was dependent on MasR, CCR2 and the MEK/ERK pathway.

Glucocorticoid-Induced Leucine Zipper Alleviates Lung Inflammation and Enhances Bacterial Clearance during Pneumococcal Pneumonia

“…In addition to inducing neutrophil apoptosis, TAT-GILZ also promoted macrophage polarization and increased efferocytosis [13]. The efferocytosis of apoptotic neutrophils by macrophages is a process mediated mainly by M2-like macrophages and is a critical stage of inflammation resolution [26]. M2-like macrophages produces antiinflammatory mediators such as IL-10 and TGF-β [26,45] and biologically active amounts of pro-resolving mediators [46].…”

“…The efferocytosis of apoptotic neutrophils by macrophages is a process mediated mainly by M2-like macrophages and is a critical stage of inflammation resolution [26]. M2-like macrophages produces antiinflammatory mediators such as IL-10 and TGF-β [26,45] and biologically active amounts of pro-resolving mediators [46]. Indeed, under M1 (IFN-γ+ LPS) polarization stimuli, BMDMs from GILZ −/− mice show increased secretion of pro-inflammatory cytokines (IL-6 and TNF-α), while secretion of the anti-inflammatory cytokine IL-10 was reduced, as compared to BMDMs from WT littermates.…”

“…Phagocytosis was evaluated as previously described [11,26]. Briefly, 2 × 10 5 alveolar macrophages AMJ2-C11 (ATCC CRL-2456) or BMDMs isolated from WT and GILZ − / − mice were plated, and incubated with S. pneumoniae (MOI 1:10) for 3 h to allow phagocytosis (1 h of adhesion at 4 • C followed by 2 h at 37 • C and 5% CO 2 ).…”

“…Noninternalized bacteria were washed out with penicillin and streptomycin (30 µg/mL in PBS by 30 min). To assess phagocytosed bacteria, macrophages were lysed as described [11,26] and viable internalized bacteria were counted in blood agar plates after overnight incubation at 37 • C and 5% CO 2 . Pre-treatment with TAT or TAT-GILZ were by 18 h before the experiments and the dose was based in previous published studies [13,27].…”

“…The identification and counts of macrophages with engulfed apoptotic bodies was performed by light microscopy (100× objective -(500 cells/slides). Results are expressed as the mean ± SEM of the percentage of macrophages with apoptotic cells inside [13,26].…”