1. Amyloid-β PET and CSF in an autopsy-confirmed cohort
Lyduine E Collij, Annemieke J M Rozemuller, Charlotte E Teunissen, Baayla D C Boon, Juhan Reimand, Femke Bouwman, Bart N M van Berckel, Philip Scheltens, Rik Ossenkoppele Ann Clin Transl Neurol . 2020 Nov;7(11):2150-2160. doi: 10.1002/acn3.51195.
Objective:Accumulation of amyloid-β is among the earliest changes in Alzheimer's disease (AD). Amyloid-β positron emission tomography (PET) and Aβ42in cerebrospinal fluid (CSF) both assess amyloid-β pathology in-vivo, but 10-20% of cases show discordant (CSF+/PET- or CSF-/PET+) results. The neuropathological correspondence with amyloid-β CSF/PET discordance is unknown.Methods:We included 21 patients from our tertiary memory clinic who had undergone both CSF Aβ42analysis and amyloid-β PET, and had neuropathological data available. Amyloid-β PET and CSF results were compared with neuropathological ABC scores (comprising of Thal (A), Braak (B), and CERAD (C) stage, all ranging from 0 [low] to 3 [high]) and neuropathological diagnosis.Results:Neuropathological diagnosis was AD in 11 (52%) patients. Amyloid-β PET was positive in all A3, C2, and C3 cases and in one of the two A2 cases. CSF Aβ42was positive in 92% of ≥A2 and 90% of ≥C2 cases. PET and CSF were discordant in three of 21 (14%) cases: CSF+/PET- in a patient with granulomatosis with polyangiitis (A0B0C0), CSF+/PET- in a patient with FTLD-TDP type B (A2B1C1), and CSF-/PET+ in a patient with AD (A3B3C3). Two CSF+/PET+ cases had a non-AD neuropathological diagnosis, that is FTLD-TDP type E (A3B1C1) and adult-onset leukoencephalopathy with axonal spheroids (A1B1C0).Interpretation:Our study demonstrates neuropathological underpinnings of amyloid-β CSF/PET discordance. Furthermore, amyloid-β biomarker positivity on both PET and CSF did not invariably result in an AD diagnosis at autopsy, illustrating the importance of considering relevant comorbidities when evaluating amyloid-β biomarker results.
2. Cerebrospinal Fluid Amyloid-β Oligomer Levels in Patients with Idiopathic Normal Pressure Hydrocephalus
Ikuko Ogino, Hanbing Xu, Masakazu Miyajima, Yumiko Motoi, Shinya Yamada, Mitsuyasu Kanai, Akihide Kondo, Shuko Nojiri, Kostadin Karagiozov, Chihiro Akiba, Chihiro Kamohara, Takeshi Ikeuchi, Madoka Nakajima, Kaito Kawamura, Hajime Arai J Alzheimers Dis . 2021;83(1):179-190. doi: 10.3233/JAD-210226.
Background:The amyloid-β oligomers, consisting of 10-20 monomers (AβO10-20), have strong neurotoxicity and are associated with cognitive impairment in Alzheimer's disease (AD). However, their role in patients with idiopathic normal pressure hydrocephalus (iNPH) is poorly understood.Objective:We hypothesized that cerebrospinal fluid (CSF) AβO10-20 accumulates in patients with iNPH, and its clearance after CSF shunting contributes to neurological improvement. We measured CSF AβO10-20 levels before and after CSF shunting in iNPH patients evaluating their diagnostic and prognostic role.Methods:We evaluated two iNPH cohorts: "evaluation" (cohort-1) with 32 patients and "validation" (cohort-2) with 13 patients. Comparison cohorts included: 27 neurologically healthy controls (HCs), and 16 AD, 15 Parkinson's disease (PD), and 14 progressive supranuclear palsy (PSP) patients. We assessed for all cohorts CSF AβO10-20 levels and their comprehensive clinical data. iNPH cohort-1 pre-shunting data were compared with those of comparison cohorts, using cohort-2 for validation. Next, we compared cohort-1's clinical and CSF data: 1) before and after CSF shunting, and 2) increased versus decreased AβO10-20 levels at baseline, 1 and 3 years after shunting.Results:Cohort-1 had higher CSF AβO10-20 levels than the HCs, PD, and PSP cohorts. This result was validated with data from cohort-2. CSF AβO10-20 levels differentiated cohort-1 from the PD and PSP groups, with an area under receiver operating characteristic curve of 0.94. AβO10-20 levels in cohort-1 decreased after CSF shunting. Patients with AβO10-20 decrease showed better cognitive outcome than those without.Conclusion:AβO10-20 accumulates in patients with iNPH and is eliminated by CSF shunting. AβO10-20 can be an applicable diagnostic and prognostic biomarker.
3. Neuroprotective effects of donepezil against Aβ25-35-induced neurotoxicity
Chun-Feng Ren, Ning-Ning Che, Xue Li, Bu-Lang Gao Eur J Med Res . 2022 Oct 28;27(1):219. doi: 10.1186/s40001-022-00862-1.
Purpose:The purpose of this study was to investigate the neuroprotective effect of donepezil against β-amyloid25-35(Aβ25-35)-induced neurotoxicity and the possible mechanism.Methods:PC12 cells were conventionally cultured. Serial concentrations of Aβ25-35and donepezil (0, 0.5, 1, 5, 10, 20 and 50 μmol/L) were added to the PC12 cells, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) staining was performed to detect the effects of these treatments on PC 12 viability. The PC 12 cells were pretreated with 1, 5, 10, 20 or 50 μmol/L donepezil two hours before 20 μmol/L Aβ25-35was added to pretreatment groups A, B, C, D and E. Normal control group I and the 20 μmol/L Aβ25-35-treated group were selected. An MTT assay was used to detect PC12 cell viability, and the level of lactate dehydrogenase (LDH) was determined. PC12 cells were pretreated with 10 μmol/L GF109203X (a protein kinase C [PKC] antagonist) 30 min before 10 μmol/L donepezil was added to pretreatment group F, and normal control group II, the 10 μmol/L GF109203X-treated group and the 10 μmol/L donepezil-treated group were chosen. The expression of phosphorylation-PKC (P-PKC) and its major substrate phosphorylated myristoylated alanine-rich protein C kinase substrate (P-MARCKS) was measured by Western blotting. The effects of donepezil on the subcellular distribution of the PKCα and PKCε isoforms were detected by immunofluorescence staining.Results:Treatment with Aβ25-35(5, 10, 20 or 50 μmol/L) for 24 h significantly (P < 0.05) decreased PC 12 cell viability in a dose-dependent manner. Compared with the PC12 cells in the control group, those in the 20 μmol/L Aβ25-35-treated group exhibited lower viability but higher LDH release. Compared with the 20 μmol/L Aβ25-35-treated group, pretreatment groups B, C, D and E exhibited significantly (P < 0.05) increased cell viability but significantly (P < 0.05) decreased LDH release. Western blotting demonstrated that compared with control, 10 μmol/L donepezil promoted PKC and MARCKS phosphorylation and that the expression of P-PKC and P-MARCKS in pretreatment group F was significantly (P < 0.05) lower than that in the donepezil-treated group. Immunofluorescence staining revealed that the PKCα and PKCε isoforms were located mainly in the cytoplasm of PC12 control cells, whereas donepezil increased the expression of the PKCα and PKCε isoforms in the membrane fraction. The Western blot results showed that donepezil altered the subcellular distribution of the PKCα and PKCε isoforms by decreasing their expression in the cytosolic fraction but increasing their expression in the membrane fraction.Conclusion:Donepezil can antagonize Aβ25-350-induced neurotoxicity in PC 12 cells, and PKC activation may account for the neuroprotective effect of donepezil.
