Tumor-associated macrophages in feline meningiomas: Exploring their prognostic significance
Maria Teresa Mandara1, Giuseppe Giglia1, Greta Benedetti1
1Department of Veterinary Medicine, University of Perugia, Italy.
Abstract:
Tumor-associated macrophages (TAMs) are the predominant immune cells in the tumor microenvironment (TME) of human meningiomas. They exhibit different functional phenotypes that contribute either to an anti-inflammatory and anti-tumor response (M1 phenotype), or an immunosuppressive and pro-tumor response (M2 phenotype). In meningiomas of cats, the specific role of TAMs in determining prognosis and post-surgery outcome remains unclear. This study aimed to characterize the macrophage population in feline meningiomas, differentiate M1 from M2 phenotype, and investigate the relationship of the results to prognosis. Fifty-seven surgically removed feline meningiomas were studied. Immunolabeling was performed on formalin-fixed paraffin embedded samples with primary antibodies anti-MAC387 (M1 macrophage), CD163 and CD204 (M2 macrophage), Iba1 (pan-macrophage), and Ki67. The cells in all cases expressed Iba1 and CD163, while MAC387 and CD204-expression varied. Moreover, macrophages were more numerous in high-grade tumors across both M1 and M2 phenotypes. Although none of the markers were predictive of recurrence on Cox models (P > .05), based on the significant association between M2 CD163-positive macrophages and high-grade tumors, and their shorter post-surgery recurrence-free times, the results suggest that M2 macrophages might play a role in the behavior and prognosis of feline meningiomas.
Insights
Tumor-associated macrophages (TAMs) are key immune cells in feline meningiomas. While M2 macrophages correlate with high-grade tumors and shorter recurrence-free times, their exact role in prognosis requires further investigation.
Area of Science:
- Veterinary Pathology
- Immunology
- Oncology
Background:
- Tumor-associated macrophages (TAMs) are prevalent immune cells in the tumor microenvironment.
- TAMs have distinct M1 (anti-tumor) and M2 (pro-tumor) phenotypes.
- The role of TAMs in feline meningiomas and their prognostic significance is not well understood.
Purpose of the Study:
- To characterize macrophage populations in feline meningiomas.
- To differentiate M1 and M2 macrophage phenotypes.
- To investigate the association between macrophage phenotypes and tumor prognosis.
Main Methods:
- Immunohistochemistry was performed on 57 feline meningiomas using antibodies for M1 (MAC387), M2 (CD163, CD204), pan-macrophage (Iba1), and proliferation (Ki67) markers.
- Macrophage populations and phenotypes were analyzed.
- Statistical analysis, including Cox models, was used to assess prognostic value.
Main Results:
- All tumors expressed Iba1 and CD163 (M2 marker).
- MAC387 (M1) and CD204 (M2) expression varied.
- Macrophage numbers, including both M1 and M2 phenotypes, were higher in high-grade tumors.
- No markers were individually predictive of recurrence via Cox models.
- A significant association was found between M2 CD163-positive macrophages, high-grade tumors, and shorter recurrence-free survival.
Conclusions:
- M2 macrophages, particularly CD163-positive cells, may be associated with aggressive behavior in feline meningiomas.
- Further research is needed to elucidate the precise role of M2 macrophages in feline meningioma prognosis and outcomes.
