scholarly journals A fragment of cell adhesion molecule L1 reduces amyloid-β plaques in a mouse model of Alzheimer’s disease

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Junkai Hu ◽  
Stanley Li Lin ◽  
Melitta Schachner

AbstractDeposition of amyloid-β (Aβ) in the brain is one of the important histopathological features of Alzheimer’s disease (AD). Previously, we reported a correlation between cell adhesion molecule L1 (L1) expression and the occurrence of AD, but its relationship was unclear. Here, we report that the expression of L1 and a 70 kDa cleavage product of L1 (L1-70) was reduced in the hippocampus of AD (APPswe) mice. Interestingly, upregulation of L1-70 expression in the hippocampus of 18-month-old APPswe mice, by parabiosis involving the joining of the circulatory system of an 18-month-old APPswe mouse with a 2-month-old wild-type C57BL/6 mouse, reduced amyloid plaque deposition. Furthermore, the reduction was accompanied by the appearance of a high number of activated microglia. Mechanistically, we observed that L1-70 could combine with topoisomerase 1 (Top1) to form a complex, L1-70/Top1, that was able to regulate expression of macrophage migration inhibitory factor (MIF), resulting in the activation of microglia and reduction of Aβ plaques. Also, transforming growth factor β1 (TGFβ-1) transferred from the blood of young wild-type C57BL/6 mice to the aged AD mice, was identified as a circulating factor that induces full-length L1 and L1-70 expression. All together, these findings suggest that L1-70 contributes to the clearance of Aβ in AD, thereby adding a novel perspective in understanding AD pathogenesis.

2021 ◽  
pp. 1-13
Author(s):  
Jonathan D. Drake ◽  
Alison B. Chambers ◽  
Brian R. Ott ◽  
Lori A. Daiello ◽  

Background: Cerebrovascular dysfunction confers risk for functional decline in Alzheimer’s disease (AD), yet the clinical interplay of these two pathogenic processes is not well understood. Objective: We utilized Alzheimer’s Disease Neuroimaging Initiative (ADNI) data to examine associations between peripherally derived soluble cell adhesion molecules (CAMs) and clinical diagnostic indicators of AD. Methods: Using generalized linear regression models, we examined cross-sectional relationships of soluble plasma vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-Selectin to baseline diagnosis and functional impairment (clinical dementia rating sum-of-boxes, CDR-SB) in the ADNI cohort (n = 112 AD, n = 396 mild cognitive impairment (MCI), n = 58 cognitively normal). We further analyzed associations of these biomarkers with brain-based AD biomarkers in a subset with available cerebrospinal fluid (CSF) data (n = 351). p-values derived from main effects and interaction terms from the linear regressions were used to assess the relationship between independent and dependent variables for significance (significance level was set at 0.05 a priori for all analysis). Results: Higher mean VCAM-1 (p = 0.0026) and ICAM-1 (p = 0.0189) levels were found in AD versus MCI groups; however, not in MCI versus cognitively normal groups. Only VCAM-1 was linked with CDR-SB scores (p = 0.0157), and APOE ɛ4 genotype modified this effect. We observed independent, additive associations when VCAM-1 and CSF amyloid-β (Aβ 42), total tau, phosphorylated tau (P-tau), or P-tau/Aβ 42 (all <  p = 0.01) were combined in a CDR-SB model; ICAM-1 showed a similar pattern, but to a lesser extent. Conclusion: Our findings indicate independent associations of plasma-based vascular biomarkers and CSF biomarkers with AD-related clinical impairment.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sofia Jacob ◽  
Gethin Davies ◽  
Marijke De Bock ◽  
Bart Hermans ◽  
Cindy Wintmolders ◽  
...  

Abstract Multiple animal models have been created to gain insight into Alzheimer’s disease (AD) pathology. Among the most commonly used models are transgenic mice overexpressing human amyloid precursor protein (APP) with mutations linked to familial AD, resulting in the formation of amyloid β plaques, one of the pathological hallmarks observed in AD patients. However, recent evidence suggests that the overexpression of APP by itself can confound some of the reported observations. Therefore, we investigated in the present study the AppNL-G-Fmodel, an App knock-in (App-KI) mouse model that develops amyloidosis in the absence of APP-overexpression. Our findings at the behavioral, electrophysiological, and histopathological level confirmed an age-dependent increase in Aβ1–42 levels and plaque deposition in these mice in accordance with previous reports. This had apparently no consequences on cognitive performance in a visual discrimination (VD) task, which was largely unaffected in AppNL-G-F mice at the ages tested. Additionally, we investigated neurophysiological functioning of several brain areas by phase-amplitude coupling (PAC) analysis, a measure associated with adequate cognitive functioning, during the VD task (starting at 4.5 months) and the exploration of home environment (at 5 and 8 months of age). While we did not detect age-dependent changes in PAC during home environment exploration for both the wild-type and the AppNL-G-F mice, we did observe subtle changes in PAC in the wild-type mice that were not present in the AppNL-G-F mice.


2020 ◽  
pp. jbc.RA120.015327
Author(s):  
Ping He ◽  
Philip Schulz ◽  
Michael R. Sierks

Conformationally distinct aggregates of the Amyloid β (Aβ) peptide accumulate in brains of Alzheimer’s disease (AD) patients, but the roles of the different aggregates in disease progression are not clear. We previously isolated two single-chain variable domain antibody fragments (scFvs), C6T and A4, that selectively bind different toxic conformational variants of oligomeric Aβ. Here we utilize these scFvs to localize the presence of these Aβ variants in human AD brain and to demonstrate their potential as therapeutic agents for treating AD. Both A4 and C6T label oligomeric Aβ in extracellular amyloid plaques, while C6T also labels intracellular oligomeric Aβ in human AD brain tissue and in an AD mouse model. For therapeutic studies, the A4 and C6T scFvs were expressed in the AD mice by viral infection of liver cells.  The scFvs were administered at 2 months of age and mice sacrificed at 9 months.  The scFvs contained a peptide tag to facilitate transport across the blood brain barrier. While treatment with C6T only slightly decreased Aβ deposits and plaque-associated inflammation, it restored neuronal integrity to wild-type levels, significantly promoted growth of new neurons, and impressively rescued survival rates to wild type levels. Treatment with A4 on the other hand significantly decreased Aβ deposits, but did not significantly decrease neuroinflammation or promote neuronal integrity, neurogenesis or survival rate. These results suggest that the specific Aβ conformation targeted in therapeutic applications greatly affects the outcome, and the location of the targeted Aβ variants may also play a critical factor.


ASN NEURO ◽  
2020 ◽  
Vol 12 ◽  
pp. 175909142092535 ◽  
Author(s):  
Naomi K. Giesers ◽  
Oliver Wirths

The deposition of amyloid-β peptides in the form of extracellular plaques and neuronal degeneration belong to the hallmark features of Alzheimer’s disease (AD). In addition, impaired calcium homeostasis and altered levels in calcium-binding proteins seem to be associated with the disease process. In this study, calretinin- (CR) and parvalbumin- (PV) positive gamma-aminobutyric acid-producing (GABAergic) interneurons were quantified in different hippocampal subfields of 12-month-old wild-type mice, as well as in the transgenic AD mouse models 5XFAD and Tg4-42. While, in comparison with wild-type mice, CR-positive interneurons were mainly reduced in the CA1 and CA2/3 regions in plaque-bearing 5XFAD mice, PV-positive interneurons were reduced in all analyzed subfields including the dentate gyrus. No reduction in CR- and PV-positive interneuron numbers was detected in the non-plaque-forming Tg4-42 mouse, although this model has been previously demonstrated to harbor a massive loss of CA1 pyramidal neurons. These results provide information about hippocampal interneuron numbers in two relevant AD mouse models, suggesting that interneuron loss in this brain region may be related to extracellular amyloid burden.


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