Myelin debris regulates inflammatory responses in an experimental demyelination animal model and multiple sclerosis lesions.
In multiple sclerosis (MS), gray matter pathology is characterized by less pronounced inflammation when compared with white matter lesions. Although regional differences in the cytoarchitecture may account for these differences, the amount of myelin debris in the cortex during a demyelinating event might also be contributory. To analyze the association between myelin debris levels and inflammatory responses, cortical areas with distinct and sparse myelination were analyzed for micro- and astrogliosis before and after cuprizone-induced demyelination in mice. In postmortem tissue of MS patients, leucocortical lesions were assessed for the type and level of inflammation in the cortical and white matter regions of the lesion. Furthermore, mice were injected intracerebrally with myelin-enriched debris, and the inflammatory response analyzed in white and grey matter areas. Our studies show that the magnitude of myelin loss positively correlates with microgliosis in the cuprizone model. In MS, the number of MHC class II expressing cells is higher in the white compared with the grey matter part of leucocortical lesions. Finally, direct application of myelin debris into the corpus callosum or cortex of mice induces profound and comparable inflammation in both regions. Our data suggest that myelin debris is an important variable in the inflammatory response during demyelinating events. Whether myelin-driven inflammation affects neuronal integrity remains to be clarified.
Institute of Neuroanatomy, Faculty of Medicine, RWTH Aachen University, Aachen, Germany.
Tim
T
Clarner
Felix
F
Diederichs
Katharina
K
Berger
Bernd
B
Denecke
Lin
L
Gan
Paul
P
van der Valk
Cordian
C
Beyer
Sandra
S
Amor
Markus
M
Kipp
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002614:Chelating Agents / Q000633:toxicity; D003337:Corpus Callosum / Q000166:cytology; D003471:Cuprizone / Q000633:toxicity; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004660:Encephalitis / Q000209:etiology*; D005260:Female; D005911:Gliosis / Q000209:etiology / Q000378:metabolism; D000949:Histocompatibility Antigens Class II; D006801:Humans; D008264:Macrophages / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008840:Microfilament Proteins / Q000378:metabolism; D017628:Microglia / Q000473:pathology; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000139:chemically induced / Q000150:complications* / Q000473:pathology*; D018991:Myelin Proteolipid Protein / Q000378:metabolism; D009186:Myelin Sheath / Q000378:metabolism*; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
C491049:Aif1 protein, mouse; D002135:Calcium-Binding Proteins; D002614:Chelating Agents; D016207:Cytokines; D000949:Histocompatibility Antigens Class II; D008840:Microfilament Proteins; D018991:Myelin Proteolipid Protein; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D003471:Cuprizone