Macrophages are central to inflammation resolution, an active process aimed at restoring tissue homeostasis following an inflammatory response. Here, the effects of db-cAMP on macrophage phenotype and function were investigated. Injection of db-cAMP into the pleural cavity of mice induced monocytes recruitment in a manner dependent on PKA and CCR2/CCL2 pathways. Furthermore, db-cAMP promoted reprogramming of bone-marrow-derived macrophages to a M2 phenotype as seen by increased Arg-1/CD206/Ym-1 expression and IL-10 levels (M2 markers). Db-cAMP also showed a synergistic effect with IL-4 in inducing STAT-3 phosphorylation and Arg-1 expression. Importantly, db-cAMP prevented IFN-γ/LPS-induced macrophage polarization to M1-like as shown by increased Arg-1 associated to lower levels of M1 cytokines (TNF-α/IL-6) and p-STAT1. In vivo, db-cAMP reduced the number of M1 macrophages induced by LPS injection without changes in M2 and Mres numbers. Moreover, db-cAMP enhanced efferocytosis of apoptotic neutrophils in a PKA-dependent manner and increased the expression of Annexin A1 and CD36, two molecules associated with efferocytosis. Finally, inhibition of endogenous PKA during LPS-induced pleurisy impaired the physiological resolution of inflammation. Taken together, the results suggest that cAMP is involved in the major functions of macrophages, such as nonphlogistic recruitment, reprogramming and efferocytosis, all key processes for inflammation resolution.

Nonphlogistic migration of macrophages contributes to the clearance of pathogens and apoptotic cells, a critical step for the resolution of inflammation and return to homeostasis. Angiotensin-(1-7) [Ang-(1-7)] is a heptapeptide of the renin-angiotensin system that acts through Mas receptor (MasR). Ang-(1-7) has recently emerged as a novel proresolving 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 toward a regulatory phenotype. Ang-(1-7) induction of CCL2 and mononuclear cell migration was also dependent on MasR and MEK/ERK. Of note, MasR was upregulated during the resolution phase of inflammation, and its 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 potentially novel proresolving 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.

Glucagon-like peptide-1 receptor agonists (GLP-1RAs), including dulaglutide, liraglutide, semaglutide, and exenatide, are effective treatments for type 2 diabetes mellitus (T2DM) and obesity. These agents mimic the action of the endogenous incretin glucagon-like peptide-1 (GLP-1) by enhancing insulin secretion, inhibiting glucagon release, and promoting weight loss through appetite suppression. GLP-1RAs have recently been suggested to have neuroprotective effects, suggesting their potential as treatment for neurodegenerative disorders, such as Alzheimer’s disease (AD). AD and T2DM share several common pathophysiological mechanisms, including insulin resistance, chronic inflammation, oxidative stress, and mitochondrial dysfunction. These shared mechanisms suggest that therapeutic agents targeting metabolic dysfunction may also be beneficial for neurodegenerative conditions. Preclinical studies on GLP-1RAs in AD models, both in vitro and in vivo, have demonstrated promising neuroprotective effects, including reductions in amyloid-beta accumulation, decreased tau hyperphosphorylation, improved synaptic plasticity, and enhanced neuronal survival. Despite the encouraging results from preclinical models, several challenges need to be addressed before GLP-1RAs can be widely used for AD treatment. Ongoing clinical trials are investigating the potential cognitive benefits of GLP-1RAs in AD patients, aiming to establish their role as a therapeutic option for AD. This review aimed to examine the current literature on preclinical and clinical studies investigating GLP-1 receptor agonists as potential therapeutic agents for AD.