Mireia Coma

A novel GSK-3β inhibitor reduces Alzheimer's pathology and rescues neuronal loss in vivo

Amyloid deposits, neurofibrillary tangles, and neuronal cell death in selectively vulnerable brain regions are the chief hallmarks in Alzheimers (AD) brains. Glycogen synthase kinase-3 (GSK-3) is one of the key kinases required for AD-type abnormal hyperphosphorylation of tau, which is believed to be a critical event in neurofibrillary tangle formation. GSK-3 has also been recently implicated in amyloid precursor protein (APP) processing/Abeta production, apoptotic cell death, and learning and memory. Thus, GSK-3 inhibition represents a very attractive drug target in AD and other neurodegenerative disorders. To investigate whether GSK-3 inhibition can reduce amyloid and tau pathologies, neuronal cell death and memory deficits in vivo, double transgenic mice coexpressing human mutant APP and tau were treated with a novel non-ATP competitive GSK-3beta inhibitor, NP12. Treatment with this thiadiazolidinone compound resulted in lower levels of tau phosphorylation, decreased amyloid deposition and plaque-associated astrocytic proliferation, protection of neurons in the entorhinal cortex and CA1 hippocampal subfield against cell death, and prevention of memory deficits in this transgenic mouse model. These results show that this novel GSK-3 inhibitor has a dual impact on amyloid and tau alterations and, perhaps even more important, on neuronal survival in vivo further suggesting that GSK-3 is a relevant therapeutic target in AD.

Brain Oligomeric β-Amyloid but Not Total Amyloid Plaque Burden Correlates With Neuronal Loss and Astrocyte Inflammatory Response in Amyloid Precursor Protein/Tau Transgenic Mice

It has long been assumed that &bgr;-amyloid (A&bgr;) had to assemble into fibrillar amyloid plaques to exert its neurotoxic effects in Alzheimer disease. An alternative hypothesis is that soluble oligomers ofA&bgr; play a much larger role in neuronal damage than the insoluble component. We have tested these competing hypotheses in vivo by studying the clinicopathologic correlates of oligomeric A&bgr; species and classic fibrillar amyloid plaques in the brains of double-transgenic APPsw-tauvlw mice up to 17 months of age. Biochemical and immunohistochemical measures of brain oligomeric A&bgr; exponentially increased with age. Oligomeric A&bgr; load correlated with morphological markers of fibrillar A&bgr; deposition. In contrast to total amyloid plaque burden, the amount of oligomeric A&bgr; deposits labeled by the conformational epitope-specific antibody Nab61 closely correlated with neuronal loss and numbers of astrocytes in the entorhinal cortex and the CA1 hippocampal subfield. However, like other morphological A&bgr;measurements, brain oligomeric A&bgr; burden did not correlate well with memory deficits in these mice. The number of glial fibrillary acidic protein-positive astrocytes in entorhinal cortex and CA1 most tightly correlated with memory impairment and neuronal cell loss. Based on these findings, we hypothesize that the astrocyte response, which is likely triggered by brain oligomeric A&bgr; accumulation, adversely affects cognition and might also contribute to neuronal cell death in this model.

Mild cholesterol depletion reduces amyloid-β production by impairing APP trafficking to the cell surface

It has been suggested that cellular cholesterol levels can modulate the metabolism of the amyloid precursor protein (APP) but the underlying mechanism remains controversial. In the current study, we investigate in detail the relationship between cholesterol reduction, APP processing and γ‐secretase function in cell culture studies. We found that mild membrane cholesterol reduction led to a decrease in Aβ40 and Aβ42 in different cell types. We did not detect changes in APP intracellular domain or Notch intracellular domain generation. Western blot analyses showed a cholesterol‐dependent decrease in the APP C‐terminal fragments and cell surface APP. Finally, we applied a fluorescence resonance energy transfer (FRET)‐based technique to study APP–Presenilin 1 (PS1) interactions and lipid rafts in intact cells. Our data indicate that cholesterol depletion reduces association of APP into lipid rafts and disrupts APP–PS1 interaction. Taken together, our results suggest that mild membrane cholesterol reduction impacts the cleavage of APP upstream of γ‐secretase and appears to be mediated by changes in APP trafficking and partitioning into lipid rafts.

The Proton-Pump Inhibitor Lansoprazole Enhances Amyloid Beta Production

A key event in the pathogenesis of Alzheimer’s disease (AD) is the accumulation of amyloid-β (Aβ) species in the brain, derived from the sequential cleavage of the amyloid precursor protein (APP) by β- and γ-secretases. Based on a systems biology study to repurpose drugs for AD, we explore the effect of lansoprazole, and other proton-pump inhibitors (PPIs), on Aβ production in AD cellular and animal models. We found that lansoprazole enhances Aβ37, Aβ40 and Aβ42 production and lowers Aβ38 levels on amyloid cell models. Interestingly, acute lansoprazole treatment in wild type and AD transgenic mice promoted higher Aβ40 levels in brain, indicating that lansoprazole may also exacerbate Aβ production in vivo. Overall, our data presents for the first time that PPIs can affect amyloid metabolism, both in vitro and in vivo.

Clinical, Neuropathologic, and Biochemical Profile of the Amyloid Precursor Protein I716F Mutation

We report the clinical, pathologic, and biochemical characteristics of the recently described amyloid precursor protein (APP) I716F mutation. We present the clinical findings of individuals carrying the APP I716F mutation and the neuropathologic examination of the proband. The mutation was found in a patient with Alzheimer disease with onset at the age of 31 years and death at age 36 years and who had a positive family history of early-onset Alzheimer disease. Neuropathologic examination showed abundant diffuse amyloid plaques mainly composed of amyloid-&bgr;42 and widespread neurofibrillary pathology. Lewy bodies were found in the amygdala. Chinese hamster ovary cells transfected with this mutation showed a marked increase in the amyloid-&bgr;42/40 ratio and APP C-terminal fragments and a decrease in APP intracellular domain production, suggesting reduced APP proteolysis by &ggr;-secretase. Taken together, these findings indicate that the APP I716F mutation is associated with the youngest age of onset for this locus and strengthen the inverse association between amyloid-&bgr;42/40 ratio and age of onset. The mutation leads to a protein that is poorly processed by &ggr;-secretase. This loss of function may be an additional mechanism by which some mutations around the &ggr;-secretase cleavage site lead to familial Alzheimer disease.

Methods for diagnosing perceived age on the basis of an ensemble of phenotypic features.

Background Perceived age has been defined as the age that a person is visually estimated to be on the basis of physical appearance. In a society where a youthful appearance are an object of desire for consumers, and a source of commercial profit for cosmetic companies, this concept has a prominent role. In addition, perceived age is also an indicator of overall health status in elderly people, since old-looking people tend to show higher rates of morbidity and mortality. However, there is a lack of objective methods for quantifying perceived age. Methods In order to satisfy the need of objective approaches for estimating perceived age, a novel algorithm was created. The novel algorithm uses supervised mathematical learning techniques and error retropropagation for the creation of an artificial neural network able to learn biophysical and clinically assessed parameters of subjects. The algorithm provides a consistent estimation of an individual’s perceived age, taking into account a defined set of facial skin phenotypic traits, such as wrinkles and roughness, number of wrinkles, depth of wrinkles, and pigmentation. A nonintervention, epidemiological cross-sectional study of cases and controls was conducted in 120 female volunteers for the diagnosis of perceived age using this novel algorithm. Data collection was performed by clinical assessment of an expert panel and biophysical assessment using the ANTERA 3D® device. Results and discussion Employing phenotype data as variables and expert assignments as objective data, the algorithm was found to correctly classify the samples with an accuracy of 92.04%. Therefore, we have developed a method for determining the perceived age of a subject in a standardized, consistent manner. Further application of this algorithm is thus a promising approach for the testing and validation of cosmetic treatments and aesthetic surgery, and it also could be used as a screening method for general health status in the population.

Novel Neuroprotective Multicomponent Therapy for Amyotrophic Lateral Sclerosis Designed by Networked Systems.

Amyotrophic Lateral Sclerosis is a fatal, progressive neurodegenerative disease characterized by loss of motor neuron function for which there is no effective treatment. One of the main difficulties in developing new therapies lies on the multiple events that contribute to motor neuron death in amyotrophic lateral sclerosis. Several pathological mechanisms have been identified as underlying events of the disease process, including excitotoxicity, mitochondrial dysfunction, oxidative stress, altered axonal transport, proteasome dysfunction, synaptic deficits, glial cell contribution, and disrupted clearance of misfolded proteins. Our approach in this study was based on a holistic vision of these mechanisms and the use of computational tools to identify polypharmacology for targeting multiple etiopathogenic pathways. By using a repositioning analysis based on systems biology approach (TPMS technology), we identified and validated the neuroprotective potential of two new drug combinations: Aliretinoin and Pranlukast, and Aliretinoin and Mefloquine. In addition, we estimated their molecular mechanisms of action in silico and validated some of these results in a well-established in vitro model of amyotrophic lateral sclerosis based on cultured spinal cord slices. The results verified that Aliretinoin and Pranlukast, and Aliretinoin and Mefloquine promote neuroprotection of motor neurons and reduce microgliosis.

Revealing the molecular relationship between type 2 diabetes and the metabolic changes induced by a very-low-carbohydrate low-fat ketogenic diet

BackgroundThe prevalence of type 2 diabetes is increasing worldwide, accounting for 85-95% of all diagnosed cases of diabetes. Clinical trials provide evidence of benefits of low-carbohydrate ketogenic diets in terms of clinical outcomes on type 2 diabetes patients. However, the molecular events responsible for these improvements still remain unclear in spite of the high amount of knowledge on the primary mechanisms of both the diabetes and the metabolic state of ketosis. Molecular network analysis of conditions, diseases and treatments might provide new insights and help build a better understanding of clinical, metabolic and molecular relationships among physiological conditions. Accordingly, our aim is to reveal such a relationship between a ketogenic diet and type 2 diabetes through systems biology approaches.MethodsOur systemic approach is based on the creation and analyses of the cell networks representing the metabolic state in a very-low-carbohydrate low-fat ketogenic diet. This global view might help identify unnoticed relationships often overlooked in molecule or process-centered studies.ResultsA strong relationship between the insulin resistance pathway and the ketosis main pathway was identified, providing a possible explanation for the improvement observed in clinical trials. Moreover, the map analyses permit the formulation of some hypothesis on functional relationships between the molecules involved in type 2 diabetes and induced ketosis, suggesting, for instance, a direct implication of glucose transporters or inflammatory processes. The molecular network analysis performed in the ketogenic-diet map, from the diabetes perspective, has provided insights on the potential mechanism of action, but also has opened new possibilities to study the applications of the ketogenic diet in other situations such as CNS or other metabolic dysfunctions.

Neuroprotective Drug for Nerve Trauma Revealed Using Artificial Intelligence

Here we used a systems biology approach and artificial intelligence to identify a neuroprotective agent for the treatment of peripheral nerve root avulsion. Based on accumulated knowledge of the neurodegenerative and neuroprotective processes that occur in motoneurons after root avulsion, we built up protein networks and converted them into mathematical models. Unbiased proteomic data from our preclinical models were used for machine learning algorithms and for restrictions to be imposed on mathematical solutions. Solutions allowed us to identify combinations of repurposed drugs as potential neuroprotective agents and we validated them in our preclinical models. The best one, NeuroHeal, neuroprotected motoneurons, exerted anti-inflammatory properties and promoted functional locomotor recovery. NeuroHeal endorsed the activation of Sirtuin 1, which was essential for its neuroprotective effect. These results support the value of network-centric approaches for drug discovery and demonstrate the efficacy of NeuroHeal as adjuvant treatment with surgical repair for nervous system trauma.

P4-210: Effects of mild cholesterol depletion on APP processing and gamma-secretase

containing cerebrosides or gangliosides significantly increased -secretase activity over a phosphatidylcholine-only baseline, whereas the addition of phosphatidylinositol significantly decreased activity. Addition of soluble cholesterol in the presence of phospholipids differentially increased the cleavage of APP-, APLP1and Notch-like substrates in a dose-dependent manner. Reconstitution of -secretase in complex lipid mixtures revealed that a lipid raft-like composition supported the highest level of activity compared to other membrane compositions, and reconstitution in a brain lipid extract yielded much higher activity than in liver or heart extracts. Conclusions: Taken together, these results demonstrate that membrane lipid composition is a direct and potent modulator of -secretase and that cholesterol, in particular, plays a major regulatory role.