Inducible nitric oxide synthase and nitrotyrosine are found in monocytes/macrophages and/or astrocytes in acute, but not in chronic, multiple sclerosis.
We have examined the localization of inducible nitric oxide synthase (iNOS) and nitrotyrosine (the product of nitration of tyrosine by peroxynitrite, a highly reactive derivative of nitric oxide [NO]) in demyelinating lesions from (i) two young adult patients with acute multiple sclerosis (MS), (ii) a child with MS (consistent with diffuse sclerosis), and (iii) five adult patients with chronic MS. Previous reports have suggested a possible correlation between iNOS, peroxynitrite, related nitrogen-derived oxidants, and the demyelinating processes in MS. We have demonstrated iNOS-immunoreactive cells in both acute-MS and diffuse-sclerosis-type lesions. In acute-MS lesions, iNOS was localized in both monocytes/macrophages and reactive astrocytes. However, foamy (myelin-laden) macrophages and the majority of reactive astrocytes were iNOS negative. In specimens from the childhood MS patient, iNOS protein was present only in a subpopulation of reactive or hypertrophic astrocytes. In contrast, no iNOS staining was detected in chronic-MS lesions. Immunohistochemical staining of acute-MS lesions with an antibody to nitrotyrosine revealed codistribution of iNOS- and nitrotyrosine-positive cells, although nitrotyrosine staining was more widespread in cells of the monocyte/macrophage lineage. In diffuse-sclerosis-type lesions, nitrotyrosine staining was present in hypertrophic astrocytes, whereas it was absent in chronic-MS lesions. These results suggest that NO and nitrogen-derived oxidants may play a role in the initiation of demyelination in acute-MS lesions but not in the later phase of the disease.
Fels Institute for Cancer Research and Molecular Biology, Department of Biochemistry and Neurology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
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Oleszak
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Zaczynska
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Bhattacharjee
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Butunoi
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Legido
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Katsetos
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies; D000911:Antibodies, Monoclonal; D001253:Astrocytes / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D002908:Chronic Disease; D002549:Diffuse Cerebral Sclerosis of Schilder / Q000201:enzymology / Q000378:metabolism; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008264:Macrophages / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000378:metabolism; D009103:Multiple Sclerosis / Q000201:enzymology / Q000209:etiology / Q000378:metabolism*; D009186:Myelin Sheath / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D000906:Antibodies; D000911:Antibodies, Monoclonal; D005904:Glial Fibrillary Acidic Protein; C096893:HAM-56 antibody; C002744:3-nitrotyrosine; D014443:Tyrosine; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II