Important Alzheimer's Disease Research Articles

The Alzheimer's disease risk gene BIN1 regulates activity-dependent gene expression in human-induced glutamatergic neurons.

Bridging Integrator 1 (BIN1) is the second most important Alzheimer's disease (AD) risk gene, but its physiological roles in neurons and its contribution to brain pathology remain largely elusive. In this work, we show that BIN1 plays a critical role in the regulation of calcium homeostasis, electrical activity, and gene expression of glutamatergic neurons. Using single-cell RNA-sequencing on cerebral organoids generated from isogenic BIN1 wild type (WT), heterozygous (HET) and homozygous knockout (KO) human-induced pluripotent stem cells (hiPSCs), we show that BIN1 is mainly expressed by oligodendrocytes and glutamatergic neurons, like in the human brain. Both BIN1 HET and KO cerebral organoids show specific transcriptional alterations, mainly associated with ion transport and synapses in glutamatergic neurons. We then demonstrate that BIN1 cell-autonomously regulates gene expression in glutamatergic neurons by using a novel protocol to generate pure culture of hiPSC-derived induced neurons (hiNs). Using this system, we also show that BIN1 plays a key role in the regulation of neuronal calcium transients and electrical activity via its interaction with the L-type voltage-gated calcium channel Cav1.2. BIN1 KO hiNs show reduced activity-dependent internalization and higher Cav1.2 expression compared to WT hiNs. Pharmacological blocking of this channel with clinically relevant doses of nifedipine, a calcium channel blocker, partly rescues electrical and gene expression alterations in BIN1 KO glutamatergic neurons. Further, we show that transcriptional alterations in BIN1 KO hiNs that affect biological processes related to calcium homeostasis are also present in glutamatergic neurons of the human brain at late stages of AD pathology. Together, these findings suggest that BIN1-dependent alterations in neuronal properties could contribute to AD pathophysiology and that treatment with low doses of clinically approved calcium blockers should be considered as an option to slow disease-onset and progression.

Generation and Study of Antibodies against Two Triangular Trimers Derived from Aβ.

Monoclonal antibodies (mAbs) that target the P-amyloid peptide (Aβ) are important Alzheimer's disease research tools and are now being used as Alzheimer's disease therapies. Conformation-specific mAbs that target oligomeric and fibrillar Aβ assemblies are of particular interest, as these assemblies are associated with Alzheimer's disease pathogenesis and progression. This paper reports the generation of rabbit mAbs against two different triangular trimers derived from Aβ. These antibodies are the first mAbs generated against Aβ oligomer mimics in which the high-resolution structures of the oligomers are known. We describe the isolation of the mAbs using single B-cell sorting of peripheral blood mononuclear cells (PBMCs) from immunized rabbits, the selectivity of the mAbs for the triangular trimers, the immunoreactivity of the mAbs with aggregated Aβ42, and the immunoreactivity of the mAbs in brain tissue from the 5xFAD Alzheimer's disease mouse model. The characterization of these mAbs against structurally defined trimers derived from Aβ enhances understanding of antibody-amyloid recognition and may benefit the development of diagnostics and immunotherapies in Alzheimer's disease.

Effect of Cocos nucifera L. Water on Scopolamine-Induced Memory Impairment in the Wistar Rat

Memory loss is an important Alzheimer's disease indicator (AD) linked with hippocampal damage. Scopolamine (SCO) antagonizes muscarinic acetylcholine receptor (mAChR) whose effect is similar to AD symptoms. Cocos nucifera L. (coconut) water is a crucial biological fluid containing nutritional components, and consumed for its health benefits. This study investigated the effect of C. nucifera water on memory impairment caused by SCO in rats. Thirty-two male Wistar rats were divided into four groups (n=8): control (normal saline); SCO (1 mg/kg/i.p.), C. nucifera water (0.4 mL/20 g) + SCO (1 mg/kg/i.p.), and donepezil (5 mg/kg/i.p.)+ SCO (1 mg/kg/i.p.). The levels of acetylcholinesterase (AChE), brain-derived neurotrophic factor (BDNF), interleukin-6 (IL-6), tumour necrosis factor (TNF-α), and cyclo-oxygenase-2 (Cox-2) were measured. Hippocampal histology was done. Utilizing GraphPad Prism for statistical analy-sis, pre-treatment with C. nucifera water and donepezil displayed higher (p<0.01) spontaneous alternation in the Y-maze, and decreased escape latency, increased entries and time spent in the target quadrant (p<0.01) of the Morris water maze compared to the SCO group. These pre-treatment also inhibited AChE activity (p<0.001), and reduced expressions of IL-6, TNF-α and Cox-2 (p<0.001). However, there were no marked differences (p>0.05) in BDNF across the groups. Histology of SCO-only group revealed degenerated neurons, whereas the pre-treated groups showed regenerated neurons with less necrotic cells. The administration of SCO to the rats resulted in some form of memory impairment, and C. nucifera water showed promise for reversing this deficits

Role of the late-onset Alzheimer's disease risk genes bin1 and ptk2b in the hyperexcitability of hiPSC-derived neurons.

The BIN1 (Bridging Integrator-1) gene is the second most important Alzheimer's disease risk gene and has been associated with synaptic transmission defects in animal models. PTK2B (Protein Tyrosine Kinase 2β) is a Ca2+ -activated non-receptor tyrosine kinase, also identified by genome-wide association study (GWAS) as an important AD risk factor, and playing a role in the mouse hippocampal synaptic plasticity. In this work, we aimed at studying the possible effects of BIN1 or PTK2B underexpression in the electrical activity taking advantage of human induced pluripotent stem cell (hiPSC)-derived neurons. To this aim, we are using hiPSCs expressing allelic variants of BIN (BIN1+/+ and BIN1-/-) or PTK2B (PTK2B+/+, PTK2B+/- and PTK2B -/-). Human induced neural progenitor cells (hiNPCs) are generated from these hiPSCs, which are further differentiated into mature neurons and glia. We evaluated the gene expression, cell type composition of cultures, and neuronal electrical activity using western blot, immunocytochemistry, pharmacological assays, and calcium imaging as a readout of the electrical function. Our preliminary data suggest that BIN1 KO decreases proliferation of NPCs. In addition, analyses of calcium imaging recordings show decreased number of active cells although, the active ones show a higher calcium spikes frequency and less synchronization. Furthermore, neuronal activity or PTK2B underexpression impairs the differentiation potential of hiNPCs into neurons. As well, and increased calcium spikes frequency in hiNs. Taken together, our preliminary panel of data suggests that both BIN1 and PTK2B regulate important biological processes involved in neuronal differentiation and electrical maturation. Thus, altered expression of these genes in the AD brain could play a role in neuronal hyperexcitability observed in patients.

Non-SELEX isolation of DNA aptamers for the homogeneous-phase fluorescence anisotropy sensing of tau Proteins

Herein, we report for the first time the isolation of DNA aptamers directed against the whole tau protein, an important Alzheimer's disease (AD) biomarker. Non-SELEX approach based on the capillary electrophoresis partitioning technique was employed to isolate a high-affinity DNA sequence pool towards the target in only three rounds and one working day. High-throughput sequencing was next performed and the recognition ability of five selected aptamers was preliminary evaluated by surface plasmon resonance using the protein target immobilized on the chip. Finally, the analytical potential of the most affine aptamer was demonstrated through the design of a homogeneous-phase fluorescence anisotropy assay. This DNA aptamer was found to be able to recognize not only the whole τ-441 but also the τ-381, τ-352, τ-383 isoforms. The sensing platform allowed the determination of these four targets with a detection limit of 28 nM, 3.2 nM, 6.3 nM and 22 nM, respectively.

Type 2 diabetes mellitus and cerebrospinal fluid Alzheimer's disease biomarker amyloid β1-42 in Alzheimer's Disease Neuroimaging Initiative participants

IntroductionType 2 diabetes mellitus (T2DM) is a risk factor for Alzheimer's disease. Cerebrospinal fluid (CSF) amyloid β (Aβ) 1-42 is an important Alzheimer's disease biomarker. However, it is inconclusive on how T2DM is related to CSF Aβ1-42. MethodsParticipants with T2DM were selected from the Alzheimer's Disease Neuroimaging Initiative by searching keywords from the medical history database. A two-way analysis of covariance model was used to analyze how T2DM associates with CSF Aβ1-42 or cerebral cortical Aβ. ResultsCSF Aβ1-42 was higher in the T2DM group than the nondiabetic group. The inverse relation between CSF Aβ1-42 and cerebral cortical Aβ was independent of T2DM status. Participants with T2DM had a lower cerebral cortical Aβ in anterior cingulate, precuneus, and temporal lobe than controls. DiscussionT2DM is positively associated with CSF Aβ1-42 but negatively with cerebral cortical Aβ. The decreased cerebral cortical Aβ associated with T2DM is preferentially located in certain brain regions.

In vitro formulation optimization of intranasal galantamine leading to enhanced bioavailability and reduced emetic response in vivo

The purpose of the current investigation was to optimize an intranasal (IN) galantamine (an acetylcholinesterase inhibitor used for treatment of Alzheimer's disease) formulation using an in vitro tissue model, to correlate those results to in vivo bioavailability, and to compare emetic response to oral dosing. A design-of-experiments (DOE) based formulation screening employing an in vitro tissue model of human nasal epithelium was used to assess drug permeability, tight junction modulation, and cellular toxicity. In vivo studies in rats compared pharmacokinetic (PK) profiles of different formulations dosed intranasally.Finally, studies in ferrets evaluated PK and gastrointestinal (GI) related side effects of oral compared to nasal dosage forms. Galantamine permeation was enhanced without increasing cytotoxicity. Pharmacokinetic testing in rats confirmed the improved drug bioavailability and demonstrated an in vitro–in vivo correlation. Compared to oral dosing, IN galantamine resulted in a dramatically lowered incidence of GI-related side effects, e.g., retching and emesis. These findings illustrate that IN delivery represents an attractive alternative to oral dosing for this important Alzheimer's disease therapeutic. To our knowledge, the data herein represent the first direct confirmation of reducing GI-related side effects for IN galantamine compared to oral dosing.