Lesions of Baló ’ s concentric sclerosis are characterized by alternating l ayers of myelinated and demyelinated tissue. The reason for concentric demyelina tion in this variant of multiple sclerosis is unclear....Lesions of Baló ’ s concentric sclerosis are characterized by alternating l ayers of myelinated and demyelinated tissue. The reason for concentric demyelina tion in this variant of multiple sclerosis is unclear. In the present study we i nvestigated the immunopathology in autopsy tissue of 14 patients with acute mult iple sclerosis or fulminant exacerbations of chronic multiple sclerosis with Bal ó - type lesions in the CNS, focusing on the patterns of tissue injury in acti vely demyelinating lesions.We found that all active concentric lesions followed a pattern of demyelination that bears resemblance s to hypoxia- like tissue injury. This was associated with high expression of i nducible nitric oxide synthase in macrophages and microglia. At the edge of acti ve lesions and, less consistently, in the outermost layer of preserved myelin, p roteins involved in tissue preconditioning,such as hypoxia- inducible factor 1 α and heat- shock protein 70, were expressed mainly in oligodendrocytes and t o a lesser degree also in astrocytes and macrophages. Due to their neuroprotecti ve effects, the rim of periplaque tissue, where these proteins are expressed, ma y be resistant to further damage in an expanding lesion and may therefore remain as a layer of preserved myelinated tissue.展开更多
文摘Lesions of Baló ’ s concentric sclerosis are characterized by alternating l ayers of myelinated and demyelinated tissue. The reason for concentric demyelina tion in this variant of multiple sclerosis is unclear. In the present study we i nvestigated the immunopathology in autopsy tissue of 14 patients with acute mult iple sclerosis or fulminant exacerbations of chronic multiple sclerosis with Bal ó - type lesions in the CNS, focusing on the patterns of tissue injury in acti vely demyelinating lesions.We found that all active concentric lesions followed a pattern of demyelination that bears resemblance s to hypoxia- like tissue injury. This was associated with high expression of i nducible nitric oxide synthase in macrophages and microglia. At the edge of acti ve lesions and, less consistently, in the outermost layer of preserved myelin, p roteins involved in tissue preconditioning,such as hypoxia- inducible factor 1 α and heat- shock protein 70, were expressed mainly in oligodendrocytes and t o a lesser degree also in astrocytes and macrophages. Due to their neuroprotecti ve effects, the rim of periplaque tissue, where these proteins are expressed, ma y be resistant to further damage in an expanding lesion and may therefore remain as a layer of preserved myelinated tissue.
