Chronic administration of AMD3100 increases survival and alleviates pathology in SOD1(G93A) mice model of ALS.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a progressive fatal neurodegenerative disease, involving both upper and lower motor neurons. The disease is induced by multifactorial pathologies, and as such, it requires a multifaceted therapeutic approach. CXCR4, a chemokine receptor widely expressed in neurons and glial cells and its ligand, CXCL12, also known as stromal-cell-derived factor (SDF1), modulate both neuronal function and apoptosis by glutamate release signaling as well as hematopoietic stem and progenitor cells (HSPCs) migration into the blood and their homing towards injured sites. Inhibition approaches towards the CXCR4/CXCL12 signaling may result in preventing neuronal apoptosis and alter the HSPCs migration and homing. Such inhibition can be achieved by means of treatment with AMD3100, an antagonist of the chemokine receptor CXCR4. METHODS: We chronically treated male and female transgenic mice model of ALS, SOD1(G93A) mice, with AMD3100. Mice body weight and motor function, evaluated by Rotarod test, were recorded once a week. The most effective treatment regimen was repeated for biochemical and histological analyses in female mice. RESULTS: We found that chronic administration of AMD3100 to SOD1(G93A) mice led to significant extension in mice lifespan and improved motor function and weight loss. In addition, the treatment significantly improved microglial pathology and decreased proinflammatory cytokines in spinal cords of treated female mice. Furthermore, AMD3100 treatment decreased blood-spinal cord barrier (BSCB) permeability by increasing tight junction proteins levels and increased the motor neurons count in the lamina X area of the spinal cord, where adult stem cells are formed. CONCLUSIONS: These data, relevant to the corresponding disease mechanism in human ALS, suggest that blocking CXCR4 by the small molecule, AMD3100, may provide a novel candidate for ALS therapy with an increased safety.

Inhibition of amyloid precursor protein beta-secretase cleavage site affects survival and motor functions of amyotrophic lateral sclerosis transgenic mice.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease defined by motor neuron loss. Recent studies have reported an increase in amyloid precursor protein (APP) levels and in its cleavage products in ALS patients indicating their possible involvement in this disease. APP is a transmembrane protein processed either by ß-secretase or α-secretase followed by γ-secretase. The APP cleavage products--soluble APP-ß (sAPPß), amyloidogenic Aß, and amino-terminal fragment N-APP--mediate a reduction in synaptic transmission, synaptic loss, neurite retraction and, ultimately, programmed cell death. OBJECTIVE: To elucidate the role of APP cleavage products in the pathology of ALS. METHODS: ALS mouse models that express mutant superoxide dismutase 1 were treated intraventricularly with a monoclonal antibody that blocks the ß-secretase cleavage site on APP. Levels of the APP cleavage product called sAPPß, motor functions and survival were assessed. RESULTS: Inhibition of APP cleavage at a presymptomatic stage resulted in a decrease in the levels of sAPPß, delay of disease onset and deterioration while at the symptomatic stage there was almost no beneficial effect. CONCLUSION: APP cleavage products might contribute to the degeneration in ALS, and early inhibition of the APP process may ameliorate disease progression.

Multifunctional Effect of Human Serum Albumin Reduces Alzheimer's Disease Related Pathologies in the 3xTg Mouse Model.

Alzheimer's disease (AD), the prevalent dementia in the elderly, involves many related and interdependent pathologies that manifests simultaneously, eventually leading to cognitive impairment and death. No treatment is currently available; however, an agent addressing several key pathologies simultaneously has a better therapeutic potential. Human serum albumin (HSA) is a highly versatile protein, harboring multifunctional properties that are relevant to key pathologies underlying AD. This study provides insight into the mechanism for HSA's therapeutic effect. In vivo, a myriad of beneficial effects were observed by pumps infusing HSA intracerebroventricularly, for the first time in an AD 3xTg mice model. A significant effect on amyloid-ß (Aß) pathology was observed. Aß1-42, soluble oligomers, and total plaque area were reduced. Neuroblastoma SHSY5Y cell line confirmed that the reduction in Aß1-42 toxicity was due to direct binding rather than other properties of HSA. Total and hyperphosphorylated tau were reduced along with an increase in tubulin, suggesting increased microtubule stability. HSA treatment also reduced brain inflammation, affecting both astrocytes and microglia markers. Finally, evidence for blood-brain barrier and myelin integrity repair was observed. These multidimensional beneficial effects of intracranial administrated HSA, together or individually, contributed to an improvement in cognitive tests, suggesting a non-immune or Aß efflux dependent means for treating AD.

Mutant SOD1 Increases APP Expression and Phosphorylation in Cellular and Animal Models of ALS.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease and it is the most common adult onset neurodegenerative disorder affecting motor neurons. There is currently no effective treatment for ALS and our understanding of the pathological mechanism is still far away from prevention and/or treatment of this devastating disease. Amyloid precursor protein (APP) is a transmembrane protein that undergoes processing either by ß-secretase or α-secretase, followed by γ-secretase. In the present study, we show that APP levels, and aberrant phosphorylation, which is associated with enhanced ß-secretase cleavage, are increased in SOD1G93A ALS mouse model. Fluorescence resonance energy transfer (FRET) analysis suggests a close interaction between SOD1 and APP at hippocampal synapses. Notably, SOD1G93A mutation induces APP-SOD1 conformational changes, indicating a crosstalk between these two signaling proteins. Inhibition of APP processing via monoclonal antibody called BBS that blocks APP ß-secretase cleavage site, resulted in reduction of mutant SOD1G93A levels in animal and cellular models of ALS, significantly prolonged life span of SOD1G93A mice and diminished inflammation. Beyond its effect on toxic mutant SOD1G93A, BBS treatment resulted in a reduction in the levels of APP, its processing product soluble APPß and pro-apoptotic p53. This study demonstrates that APP and its processing products contribute to ALS pathology through several different pathways; thus BBS antibody could be a promising neuroprotective strategy for treatment of this disease.

Immunomodulation of AßPP processing alleviates amyloid-ß-related pathology in Alzheimer's disease transgenic mice.

Among the different paradigms aimed at interfering with amyloid-ß (Aß)-related pathology, the attenuation of amyloid-ß protein precursor (AßPP) processing to limit Aß levels seems to be a promising one. Along with the development of BACE1 inhibitors, and the generation of its knock-out mice, accumulating data raise concerns regarding a total inhibition of the enzyme as it shares the processing of other substrates. We described a novel approach to interfere with the specific interaction between AßPP and BACE1 using monoclonal antibodies directed to the ß-secretase cleavage site upon the substrate, AßPP. Such antibodies limit AßPP cleavage in a cellular model of Alzheimer's disease (AD) and avoid the total inhibition of BACE1. Here, we demonstrate the ability of AßPP ß-site antibodies to interfere with Aß production in vivo. Systemic antibody treatment diminished Aß plaques, membrane-associated oligomers, and intracellular Aß accumulation, all of which have been implicated in cellular death and synaptic loss, suggesting that this approach may be an applicable strategy for AD treatment.