Glial transforming growth factor (TGF)-β isotypes in multiple sclerosis: Differential glial expression of TGF-β1, 2 and 3 isotypes in multiple sclerosis

We studied glial transforming growth factor (TGF)-β isotype expression in 14 cases of multiple sclerosis. Acute active lesions exhibited selective TGF-β 2 immunoreactivity of lesion encircling ramified microglia. In contrast, astrocytes within chronic active white matter lesions expressed all three isotypes. Chronic active lesions which extended into cortex exhibited selective cortical astrocyte TGF-β 2 expression. This isotype was also selectively expressed by astrocytes in apparently normal white matter. A similar pattern of glial TGF-β expression was seen in the pathological control, progressive multifocal leukoencephalopathy. The results suggest that TGF-β cytokines are locally expressed in demyelination and that the β2 isotype may be uniquely regulated.