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Updated: Mar 31, 2026
Depletion and Reconstitution of Macrophages in Mice
Published on: August 1, 2012
Azithromycin protects mice against ischemic stroke injury by promoting macrophage transition towards M2 phenotype
Diana Amantea1, Michelangelo Certo1, Francesco Petrelli1
1Section of Preclinical and Translational Pharmacology, Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende (CS), Italy.
Abstract:
To develop novel and effective treatments for ischemic stroke, we investigated the neuroprotective effects of the macrolide antibiotic azithromycin in a mouse model system of transient middle cerebral artery occlusion. Intraperitoneal administration of azithromycin significantly reduced blood-brain barrier damage and cerebral infiltration of myeloid cells, including neutrophils and inflammatory macrophages. These effects resulted in a dose-dependent reduction of cerebral ischemic damage, and in a remarkable amelioration of neurological deficits up to 7 days after the insult. Neuroprotection was associated with increased arginase activity in peritoneal exudate cells, which was followed by the detection of Ym1- and arginase I-immunopositive M2 macrophages in the ischemic area at 24-48 h of reperfusion. Pharmacological inhibition of peritoneal arginase activity counteracted azithromycin-induced neuroprotection, pointing to a major role for drug-induced polarization of migratory macrophages towards a protective, non-inflammatory M2 phenotype.
Insights
Azithromycin shows neuroprotective effects against ischemic stroke by reducing brain damage and improving neurological function in mice. This protection is linked to promoting anti-inflammatory M2 macrophages.
Area of Science:
- Neuroscience
- Pharmacology
- Immunology
Background:
- Ischemic stroke poses a significant therapeutic challenge.
- Novel treatments are needed to mitigate brain damage and improve recovery.
- Macrolide antibiotics like azithromycin are being explored for non-antimicrobial properties.
Purpose of the Study:
- To investigate the neuroprotective potential of azithromycin in a mouse model of ischemic stroke.
- To elucidate the underlying mechanisms of azithromycin's effects on the brain and immune system.
Main Methods:
- Transient middle cerebral artery occlusion (tMCAO) mouse model.
- Intraperitoneal administration of azithromycin.
- Assessment of blood-brain barrier integrity and myeloid cell infiltration.
- Measurement of arginase activity and M2 macrophage polarization.
- Pharmacological inhibition of arginase.
Main Results:
- Azithromycin significantly reduced blood-brain barrier damage and myeloid cell infiltration in the ischemic brain.
- A dose-dependent reduction in cerebral ischemic damage and improved neurological deficits were observed.
- Neuroprotection correlated with increased arginase activity and M2 macrophage presence in the ischemic area.
- Inhibition of arginase activity abolished azithromycin-induced neuroprotection.
Conclusions:
- Azithromycin exerts significant neuroprotective effects in ischemic stroke.
- The mechanism involves promoting the polarization of macrophages to a protective M2 phenotype via arginase activity.
- Azithromycin represents a potential therapeutic agent for ischemic stroke treatment.
