Altered Sphingolipid Balance in Capillary Cerebral Amyloid Angiopathy.
BACKGROUND
The majority of patients with Alzheimer's disease (AD) exhibit amyloid-β (Aβ) deposits at the brain vasculature, a process referred to as cerebral amyloid angiopathy (CAA). In over 51% of AD cases, Aβ also accumulates in cortical capillaries, which is termed capillary CAA (capCAA). It has been postulated that the presence of capCAA in AD is a specific subtype of AD, although underlying mechanisms are not yet fully understood. Sphingolipids (SLs) are implicated in neurodegenerative disorders, including AD. However, to date it remains unknown whether alterations in the SL pathway are involved in capCAA pathogenesis and if these differ from AD.


OBJECTIVE
To determine whether AD cases with capCAA have an altered SL profile compared to AD cases without capCAA.


METHODS
Immunohistochemistry was performed to assess the expression and localization of ceramide, acid sphingomyelinase (ASM), and sphingosine-1-phosphate receptors (S1P1, S1P3). In addition, we determined the concentrations of S1P as well as different chain-lengths of ceramides using HPLC-MS/MS.


RESULTS
Immunohistochemical analysis revealed an altered expression of ceramide, ASM, and S1P receptors by reactive astrocytes and microglial cells specifically associated with capCAA. Moreover, a shift in the balance of ceramides with different chain-lengths and S1P content is observed in capCAA.


CONCLUSIONS
Here we provide evidence of a deregulated SL balance in capCAA. The increased levels of ASM and ceramide in activated glia cells suggest that the SL pathway is involved in the neuroinflammatory response in capCAA pathogenesis. Future research is needed to elucidate the role of S1P in capCAA.
Department of Molecular Cell Biology and Immunology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
Nienke M
NM
de Wit
Department of Pathology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
Hripsime
H
Snkhchyan
Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands.
Sandra
S
den Hoedt
Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands.
Darcos
D
Wattimena
Laboratorium Pathology Oost Nederland, Enschede, The Netherlands.
Rob
R
de Vos
Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands.
Monique T
MT
Mulder
Department of Neurology, University of Bonn, Bonn, Germany.
Jochen
J
Walter
Department of Neuroscience, School of Mental Health and Neuroscience, Maastricht University, The Netherlands.
Pilar
P
Martinez-Martinez
Department of Pathology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
Jeroen J
JJ
Hoozemans
Department of Pathology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
Annemieke J
AJ
Rozemuller
Department of Molecular Cell Biology and Immunology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
Helga E
HE
de Vries
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D000682:Amyloid / Q000378:metabolism; D001253:Astrocytes / Q000378:metabolism / Q000473:pathology; D002196:Capillaries / Q000378:metabolism* / Q000473:pathology; D016657:Cerebral Amyloid Angiopathy / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D017628:Microglia / Q000378:metabolism / Q000473:pathology; D009778:Occipital Lobe / Q000378:metabolism* / Q000473:pathology; D049349:Receptors, Lysosphingolipid / Q000378:metabolism; D013107:Sphingolipids / Q000378:metabolism*; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism
D000682:Amyloid; D049349:Receptors, Lysosphingolipid; D013107:Sphingolipids; D013108:Sphingomyelin Phosphodiesterase
Acid sphingomyelinase; Alzheimer’s disease; capillary cerebral amyloid angiopathy; ceramide; inflammation; neurodegenerative disease; sphingosine-1-phosphate