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Updated: Dec 15, 2025
In Vitro Assay to Study Tumor-macrophage Interaction
Published on: August 1, 2019
Tumor-associated macrophage infiltration in meningioma
Dustin T Proctor1, Jordan Huang1,2,3, Sanju Lama1,2,3
1Project neuroArm, Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
Background:
Meningioma, a most common brain tumor, has a high rate of recurrence. Tumor-associated macrophages (TAMs) are the most abundant immune cell type in meningioma. TAMs display functional phenotypic diversity and may establish either an inflammatory and anti-tumoral or an immunosuppressive and pro-tumoral microenvironment. TAM subtypes present in meningioma and potential contribution to growth and recurrence is unknown.
Methods:
Immunofluorescence staining was used to quantify M1 and M2 TAM populations in tissues obtained from 30 meningioma patients. Associations between M1 and M2 cells, M1:M2 cell ratio to tumor characteristics, WHO grade, recurrence, size, location, peri-tumoral edema, and patient demographics such as age and sex were examined.
Results:
TAM cells accounted for ~18% of all cells in meningioma tissues. More than 80% of infiltrating TAMs were found to be of pro-tumoral M2 phenotype and correlated to tumor size (P = .0409). M1:M2 cell ratio was significantly decreased in WHO grade II, compared to grade I tumors (P = .009). Furthermore, a 2.3-fold difference in M1:M2 ratio between primary (0.14) and recurrent (0.06) tumors was observed (n = 18 and 12 respectively, P = .044).
Conclusion:
This study is the first to confirm existence of pro-tumoral M2 TAMs in the meningioma microenvironment, emphasizing its potential role in tumor growth and recurrence.
Insights
Pro-tumoral M2 tumor-associated macrophages (TAMs) are prevalent in meningioma, correlating with tumor size and recurrence. This suggests M2 TAMs play a key role in meningioma growth and recurrence.
Area of Science:
- Neuro-oncology
- Immunology
- Pathology
Background:
- Meningioma is a common brain tumor with a high recurrence rate.
- Tumor-associated macrophages (TAMs) are abundant in meningioma and can be either anti-tumoral or pro-tumoral.
- The specific TAM subtypes in meningioma and their role in tumor growth and recurrence are unknown.
Purpose of the Study:
- To investigate the presence and subtypes of TAMs in meningioma.
- To determine the association of TAM subtypes with tumor characteristics and recurrence.
Main Methods:
- Immunofluorescence staining was used to quantify M1 and M2 TAM populations in 30 meningioma tissues.
- The M1:M2 cell ratio was analyzed in relation to tumor grade, size, recurrence, and patient demographics.
Main Results:
- Tumor-associated macrophages constituted approximately 18% of cells in meningioma tissues.
- Over 80% of TAMs were of the pro-tumoral M2 phenotype, correlating with tumor size (P = .0409).
- The M1:M2 ratio was significantly lower in WHO grade II tumors versus grade I (P = .009) and differed between primary and recurrent tumors (P = .044).
Conclusions:
- This study confirms the presence of pro-tumoral M2 TAMs in the meningioma microenvironment.
- M2 TAMs are associated with increased tumor size and recurrence.
- Targeting M2 TAMs may offer a therapeutic strategy for meningioma.
