New approach for treating Alzheimer’s shows success in mouse models

by Ben-Gurion University of the Negev

VDAC1 is highly expressed in the neuropil surrounding the Aβ plaques of the 5 × FAD mouse model. a–d Representative cortical and hippocampal sections from WT and 5 × FAD mice treated and untreated with VBIT-4, IHC stained for Aβ (a, b) or VDAC1 (c, d). Higher magnifications of selected areas are shown within the dashed-line squares. e Confocal IF images of cortical and hippocampal sections from 5 × FAD mice co-IF-stained for Aβ and VDAC1. The over-expressed VDAC1 rings are formed around the Aβ plaques. f–h Quantitative analysis of VDAC1 expression levels in cortical sections outside the plaques (g), (area a in f) and in the neuropil surrounding the Aβ plaques (h), (area b in f); in h, numbers are relative to levels outside of the plaque (a). Results show means ± SEM (n = 3). **P < 0.01, ***P < 0.001, ****P < 0.0001. i Representative Co-IF staining of cortical sections from 5 × FAD mice for VDAC1 and neuronal markers (TUBB3, NeuN, synaptophysin); microglia (IBA1) or astrocytes (GFAP). Credit: Translational Neurodegeneration (2022). DOI: 10.1186/s40035-022-00329-7

The growing number of Alzheimer’s disease (AD) cases, projected to reach 135 million by 2050, highlights the urgent need for effective therapeutics. Accumulated evidence points to an impairment of the metabolic mechanism in Alzheimer’s patients that develops several decades before the onset of dementia and deterioration of cognitive function. Reduced metabolism results from a dysfunction of the mitochondria, which is responsible for producing most of the energy in the cell but is also involved in cell death, inflammation and immune response.

Despite the disease being linked to mitochondrial dysfunction, currently, no drug candidates have targeted this aspect. Researchers at Ben-Gurion University of the Negev are proposing a new treatment approach by targeting the mitochondrial gatekeeper, the voltage-dependent anion channel-1 (VDAC1), which controls mitochondrial activity and controls cell life and death.

The new proposed target and therapy demonstrated significant improvement across multiple parameters in mouse models, as reported in the journal Translational Neurodegeneration.

VDAC1 plays a crucial role in the cell death process mediated by mitochondria, which is why the team of researchers led by Prof. Varda Shoshan-Barmatz chose to focus their efforts on the dysfunction of the mitochondria in a mouse model for Alzheimer’s disease as a target for treatment.

Prof. Shoshan-Barmatz’s research showed that an increase in the amount of the VDAC1 protein in the cell leads to its organization as a ring, with a large channel through which death-factor proteins and mitochondrial DNA exit, causing cell death and an immune response, respectively. A high increase in VDAC1 levels has been found in heart diseases, intestinal diseases (Crohn’s), autoimmune diseases (lupus) and others. Here, the researchers show that the protein is produced in huge levels in the brain of a mouse model for Alzheimer’s disease and is concentrated in the nerve cells around the plaque, leading to their death.

Prof. Shoshan-Barmatz has developed a small molecule, VBIT-4, that binds to VDAC1 and prevents the pathophysiological changes associated with Alzheimer’s. VBIT-4, a molecule that can cross the blood-brain barrier (BBB), was able to prevent the pathophysiological changes associated with Alzheimer’s disease, such as neuronal cell death, neuroinflammation and neuro-metabolic dysfunctions. Additionally, it also induced a neuroprotective phenotype in astrocytes and microglia, which are normally pro-inflammatory and neurotoxic.

This means that not only did the treatment protect against degeneration, it also promoted the healthy growth and normal functioning of neurons. Furthermore, the therapy also prevented decline of cognitive skills such as learning and memory in the mice.

Interestingly, the protective effects were achieved without significantly reducing Tau or amyloid (Aβ) plaques, which are commonly believed to be the main causes of Alzheimer’s. This suggests that the Aβ-cascade hypothesis, which posits that these elements are the primary cause of the disease, may not accurately reflect the underlying cause of Alzheimer’s disease.

“Targeting VDAC1 with a novel molecule we developed presents an innovative approach to Alzheimer’s treatment, and can even be used as a preventive treatment,” said lead author Prof. Shoshan-Barmatz.