Wheat germ agglutinin enhanced cerebral uptake of anti-Aβ antibody after intranasal administration in 5XFAD mice

Real-Time Dissecting the Dynamics of Drug Transportation in the Live Brain

Brain diseases are becoming a more and more serious threat to human health. Many critical properties of the transport mechanisms of drugs in live brains remain poorly understood. In this work, single-particle tracking was used to dissect the transport dynamics of wheat germ agglutinin (WGA) in live brain and characterize the geometry and rheology of the extracellular space (ECS). The results revealed that the movements of WGA were influenced by the specific-binding molecules and the nature of the ECS. We further analyzed the mobility behaviors of WGA globally and quantitatively and found that movement of WGA in brain cells of acute slices was an active transport process associated with actin filaments and microtubules. This work paves the way for studies aiming at characterizing the biophysics of drug transport in the context of live brains, which may contribute to developing potential new therapeutic applications for brain diseases.

MicroRNA silencing: A promising therapy for Alzheimer's disease

Alzheimer's disease (AD) is a global health crisis currently afflicting ~6 million Americans (and ~40 million people worldwide). By the middle of the century, these numbers will stagger by ~16 million Americans (and ~152 million people worldwide) suffering from AD, if breakthrough disease-modifying treatments are not discovered. Currently, there are no treatments to prevent, halt or cure the disease. Multiple independent studies on brain gene expression patterns have indicated that in AD about 1/3rd of the genes are upregulated while the rest 2/3rd of the genes are downregulated. In that regard, AD therapeutics focused on antagomiR-mediated silencing of"upregulated"microRNAs (miRs) may be more feasible since upregulated miRs in AD continue to increase with the disease progression, as opposed to agomiR-mediated overexpression of down-regulated miRs with unpredictable reduced presence and relative short-life of 1-3h under pathological conditions in AD brain. Studies reported thus far indicate that most of the upregulated pathogenic genes in AD are regulated by pro-inflammatory microRNAs (miRs). Given the precedence of chronic neuroinflammation in triggering AD-like neurodegeneration and multifactorial nature of AD, silencing inflammation-specific micro-RNAs using antisense-microRNAs may be an effective adjuvant therapeutic strategy to prevent, halt or cure AD.

Amyloid Beta Oligomers Target to Extracellular and Intracellular Neuronal Synaptic Proteins in Alzheimer's Disease

Introduction: β-Amyloid protein (Aβ) putatively plays a seminal role in synaptic loss in Alzheimer's disease (AD). While there is no consensus regarding the synaptic-relevant species of Aβ, it is known that Aβ oligomers (AβOs) are noticeably increased in the early stages of AD, localizing at or within the synapse. In cell and animal models, AβOs have been shown to attach to synapses and instigate synapse dysfunction and deterioration. To establish the pathological mechanism of synaptic loss in AD, it will be important to identify the synaptic targets to which AβOs attach. Methods: An unbiased approach using far western ligand blots has identified three synaptic proteins to which AβOs specifically attach. These proteins (p100, p140, and p260) were subsequently enriched by detergent extraction, ultracentrifugation, and CHT-HPLC column separation, and sequenced by LC-MS/MS. P100, p140, and p260 were identified. These levels of AβOs targets in human AD and aging frontal cortexes were analyzed by quantitative proteomics and western-blot. The polyclonal antibody to AβOs was developed and used to block the toxicity of AβOs. The data were analyzed with one-way analysis of variance. Results: AβOs binding proteins p100, p140, and p260 were identified as Na/K-ATPase, synGap, and Shank3, respectively. α3-Na/K-ATPase, synGap, and Shank3 proteins showed loss in the postsynaptic density (PSD) of human AD frontal cortex. In short term experiments, oligomers of Aβ inhibited Na/K-ATPase at the synapse. Na/K-ATPase activity was restored by an antibody specific for soluble forms of Aβ. α3-Na/K-ATPase protein and synaptic β-amyloid peptides were pulled down from human AD synapses by co-immunoprecipitation. Results suggest synaptic dysfunction in early stages of AD may stem from inhibition of Na/K-ATPase activity by Aβ oligomers, while later stages could hypothetically result from disrupted synapse structure involving the PSD proteins synGap and Shank3. Conclusion: We identified three AβO binding proteins as α3-Na/K-ATPase, synGap, and Shank3. Soluble Aβ oligomers appear capable of attacking neurons via specific extracellular as well as intracellular synaptic proteins. Impact on these proteins hypothetically could lead to synaptic dysfunction and loss, and could serve as novel therapeutic targets for AD treatment by antibodies or other agents.

Laminar specific detection of APP induced neurodegeneration and recovery using MEMRI in an olfactory based Alzheimer's disease mouse model

Manganese enhanced MRI (MEMRI) was used to detect specific laminar changes in the olfactory bulb (OB) to follow the progression of amyloid precursor protein (APP)-induced neuronal pathology and its recovery in a reversible olfactory based Alzheimer's disease (AD) mouse model. Olfactory dysfunction is an early symptom of AD, which suggests that olfactory sensory neurons (OSNs) may be more sensitive to AD related factors than neurons in other brain areas. Previously a transgenic mouse model was established that causes degeneration of OSNs by overexpressing humanized APP (hAPP), which results in a disruption of the olfactory circuitry with changes in the glomerular structure. In the present work, OB volume and manganese enhancement of the glomerular layer in the OB were decreased in mutant mice. Turning off APP overexpression with doxycycline produced a significant increase in manganese enhancement of the glomerular layer after only 1week, and further recovery after 3weeks, while treatment with Aβ antibody produced modest improvement with MRI measurements. Thus, MEMRI enables a direct tracking of laminar specific neurodegeneration through a non-invasive in vivo measurement. The use of MRI will enable assessment of the ability of different pharmacological reagents to block olfactory neuronal loss and can serve as a unique in vivo screening tool to both identify potential therapeutics and test their efficacy.

Brain Uptake of Neurotherapeutics after Intranasal versus Intraperitoneal Delivery in Mice

There is a growing global prevalence of neurodegenerative diseases such as Alzheimer's disease and dementia. Current treatment for neurodegenerative diseases is limited due to the blood brain barrier's ability to restrict the entry of therapeutics to the brain. In that context, direct delivery of drugs from nose to brain has gained emerging interest as an important alternative to oral and parenteral routes of administration. Although there are considerable reports showing promising results after intranasal drug delivery in various disease-models and investigatory human clinical trials, there are very few studies showing a detailed pharmacokinetics with regard to the uptake and retention of intranasally delivered material(s) within specific brain regions, which are critical determining factors for dosing conditions and optimal treatment regimen. This investigation compared a time-dependent brain uptake and resident time of various radiolabeled candidate neurotherapeutics after a single bolus intranasal or intraperitoneal administration in mice. Results indicate that the brain uptake of intranasally delivered therapeutic(s) is > 5 times greater than that after intraperitoneal delivery. The peak uptake and resident time of all intranasally delivered test therapeutics for all brain regions is observed to be between 30min-12h, depending upon the distance of brain region from the site of administration, followed by gradual fading of radioactive counts by 24h post intranasal administration. Current study confirms the usefulness of intranasal administration as a non- invasive and efficient means of delivering therapeutics to the brain to treat neurodegenerative diseases including Alzheimer's disease.