Different content of chitin-like polysaccharides in multiple sclerosis and Alzheimer's disease brains.
Chitin is an insoluble N-acetyl-glucosamine polymer coating fungi cell wall and several human parasites. It is hydrolysed by chitotriosidase (Chit); however, as chitin is absent in humans, the significance of human Chit activity is unknown. The level of plasma Chit activity positively correlates with Alzheimer's disease (AD) and multiple sclerosis (MS). A recent study revealed the presence of potentially detrimental chitin-like substances in AD brain by Calcofluor histochemistry, whilst its search in MS brains has never been described to date. Through a comparative immunohistochemical analysis we confirm the presence of abundant chitin-like deposition in AD brains but fail to demonstrate it in MS brains. Interestingly, co-localization of beta-amyloid, Calcofluor and the nuclear marker DAPI was observed. Therefore, Chit production in MS patients is induced by mechanisms other than those operating in AD. Microglia-derived Chit activity in MS may counterbalance the naturally occurring glucosamine aggregation, protecting the brain from the chitin-like substance deposition.
Sotgiu
Stefano
S
Dipartimento di Neuroscienze e Scienze Materno-Infantili, University of Sassari, Italy. stefanos@uniss.it
Musumeci
Salvatore
S
Marconi
Silvia
S
Gini
Beatrice
B
Bonetti
Bruno
B
D000117:Acetylglucosamine / Q000378:metabolism; D000368:Aged; D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology; D001923:Brain Chemistry; D002686:Chitin / Q000032:analysis / Q000378:metabolism*; D005625:Frontal Lobe / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008264:Macrophages / Q000737:chemistry / Q000378:metabolism; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000378:metabolism* / Q000473:pathology; D011134:Polysaccharides / Q000032:analysis / Q000378:metabolism*; D013702:Temporal Lobe / Q000737:chemistry / Q000378:metabolism
D011134:Polysaccharides; D002686:Chitin; D000117:Acetylglucosamine