Glia 2002 Oct;40(1):121-9
Werner K, Bitsch A, Bunkowski S, Hemmerlein B, Bruck W.
Department of Neuropathology, Charite, Humboldt-Universitat, Campus Virchow-Klinikum, Berlin, Germany.
The activation of macrophages/microglia in multiple sclerosis (MS) lesions plays a central role in the effector phase of myelin breakdown.
The precise patterns of macrophage/microglia activation during demyelination have not yet been defined.
The growth and activating factor macrophage-colony stimulating factor (M-CSF) and its specific receptor (M-CSFR) may be involved in this process.
The present study investigated the expression of M-CSF and M-CSFR mRNA by in situ hybridization in 60 lesions from 32 MS patients.
In the control and periplaque white matter, microglia was almost completely M-CSFR positive.
Irrespective of the demyelinating activity, an increased number of cells expressed M-CSF or M-CSFR mRNA within the lesions.
However, despite the tremendous increase in macrophages/microglia within the lesions, the relative number of these cells expressing M-CSF or M-CSFR decreased.
There was no correlation of M-CSF or M-CSFR expression with active myelin breakdown.
The correlation between the clinical course and the expression of M-CSF or M-CSFR mRNA revealed significant differences with the lowest expression in primary progressive MS.
These results suggest a downregulation of M-CSF and M-CSFR inside the MS plaque probably due to the high amount of macrophage-derived cytokines or mediators.
Nevertheless, the differences in the relative number of cells expressing the M-CSF/M-CSFR pathway implicate that this pathway may be an important contributory factor in different forms of MS pathology.