Multiple sclerosis: The resolving lesion revealed

A little studied lesion, the resolving lesion, is described in multiple sclerosis (MS). Unusual features of early resolving lesions comprised a fibrous astrogliotic parenchyma replete with lipid-laden (foamy) microglia/macrophages widely scattered throughout and lined up at the edge, separating demyelinated plaque from myelinated white matter. Ongoing myelin breakdown was absent, as was remyelination. Later resolving lesions displayed the unusual coexistence of macrophages and remyelination within the gliotic parenchyma. Collectively, these observations may provide for the first time evidence for a role in MS for mitigating factors like alternatively-activated (M2) microglia/macrophages, known to have an anti-inflammatory phenotype and to be associated with wound-healing and repair.