Glioma grade is associated with the accumulation and activity of cells bearing M2 monocyte markers
Menée sur des échantillons tumoraux prélevés sur des patients atteints d'un gliome de grade II à IV, cette étude suggère que la mesure de l'expression de certains marqueurs des macrophages M2 permet de distinguer les astrocytomes de grade II et IV
Purpose: This study is directed at identifying the cell source(s) of immunomodulatory cytokines in high grade gliomas and establishing whether the analysis of associated markers has implications for tumor grading.
Experimental Design: Glioma specimens classified as WHO Grade II-IV by histopathology were assessed by gene expression analysis and immunohistochemistry to identify the cells producing IL-10, which was confirmed by flow cytometry and factor secretion in culture. Finally, Principal Component Analysis (PCA) and Mixture Discriminant Analysis (MDA) were used to investigate associations between expressed genes and glioma grade.
Results: The principle source of glioma-associated IL-10 is a cell type that bears phenotype markers consistent with M2 monocytes but does not express all M2-associated genes. Measures of expression of the M2 cell markers CD14, CD68, CD163 and CD204, which are elevated in high grade gliomas, and the neutrophil/MDSC subset marker CD15, which is reduced, provide the best index of glioma grade.
Conclusions: Grade II and IV astrocytomas can be clearly differentiated based on the expression of certain M2 markers in tumor tissues while Grade III astrocytomas exhibit a range of expression between the lower and higher grade specimens. The content of CD163+ cells distinguishes Grade III astrocytoma subsets with different prognosis.
Clinical Cancer Research , résumé, 2013