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Updated: Aug 30, 2025
Depletion and Reconstitution of Macrophages in Mice
Published on: August 1, 2012
Distribution of M1 and M2 macrophages in cerebral granulomas caused by Encephalitozoon cuniculi
Adolfo Soto-Domínguez1, Jennifer A González-Castillo2, Uziel Castillo-Velázquez2
1Cuerpo Académico Consolidado de Morfología e Histología, Mexico.
Abstract:
Encephalitozoon cuniculi spores cause severe granulomatous inflammation in the brain where mononuclear cells and macrophages infiltrate. Here, we orally infected New Zealand white rabbits with 1 × 106E. cuniculi viable spores to study the recruitment and localization of macrophages in brain granulomas. At day 30 post-infection, the positive phenotype markers iNOS (M1) and Arg-1 (M2) were located in the periphery and center of granulomas, respectively. Live intracytoplasmic spores were found only in positive Arg-1 cells. This is the first work to describe the recruitment and distribution of M1 and M2 macrophages in the brain granulomas of rabbits infected with E. cuniculi.
Insights
Encephalitozoon cuniculi infection causes brain inflammation. This study reveals M1 and M2 macrophages concentrate in different brain granuloma areas, with live spores found in M2 macrophages.
Area of Science:
- Neuroimmunology
- Parasitology
- Veterinary Pathology
Background:
- Encephalitozoon cuniculi (E. cuniculi) spores trigger severe granulomatous brain inflammation.
- Mononuclear cells and macrophages are key infiltrators in these inflammatory sites.
Purpose of the Study:
- To investigate the recruitment and spatial distribution of M1 and M2 macrophages within brain granulomas.
- To characterize macrophage phenotypes in response to E. cuniculi infection in a rabbit model.
Main Methods:
- Oral infection of New Zealand white rabbits with 1 × 10^6 E. cuniculi viable spores.
- Analysis of macrophage phenotype markers (iNOS for M1, Arg-1 for M2) at 30 days post-infection.
- Localization of live intracytoplasmic spores within specific macrophage populations.
Main Results:
- M1 macrophages (iNOS positive) were predominantly found at the granuloma periphery.
- M2 macrophages (Arg-1 positive) were concentrated in the granuloma center.
- Live E. cuniculi spores were exclusively observed within Arg-1 positive (M2) macrophages.
Conclusions:
- This study provides the first detailed description of M1 and M2 macrophage distribution in E. cuniculi-induced brain granulomas in rabbits.
- Macrophage polarization (M1/M2) is spatially organized within brain granulomas during E. cuniculi infection.
- M2 macrophages play a crucial role in harboring live E. cuniculi spores within the brain.
