Intervenção na Neurodegeneração Através da Sinalização RhoA e Reforço da Função Microglial

Compelling evidence suggests that neuroinflammation is central to the onset and progression of neurodegenerative diseases, including AD. Microglia (MG), the resident immune cells of the central nervous system (CNS), are the main cellular component of neuroinflammation. Preventing or reducing MG-mediated neuroinflammation and the production of inflammatory mediators driving the progressive synaptic and neuronal loss and cognitive deterioration in neurodegenerative disorders is a major objective for effective neuroprotection. Despite efforts to find a cure for AD, the goal has yet to be attained. While the current pharmacological treatments available for AD mainly target Aß and tau pathologies, they have only shown modest improvements in cognitive decline and cannot slow down the neurodegenerative process [14], which is critical to mitigating the AD pandemic we face. We have recently shown that loss of the RhoGTPase RhoA in MG is sufficient to trigger spontaneous MG-mediated neuroinflammation, resulting in AD-like neurodegeneration [4]. Importantly, we have now shown that RhoA activity is decreased in brain MG of human AD patients (Annex 1). Based on our results and recent work from others [4-6], we posited that diminishing microglial RhoA activity is critical in triggering MG reactivity and neuroinflammation that may lead to AD-like neurodegeneration. In this project grant, we will test this hypothesis. Therefore, the two main objectives of the NEUROSAFE project are: First, using phosphoproteomics, bioinformatics, and high-content FRET-based validation of relevant signaling molecules, together with intravital imaging, we will understand in molecular detail why diminishing MG RhoA activity disrupts MG homeostasis and specifically leads to spontaneous MG reactivity. Second, to test, using AAV-mediated transduction of hippocampal MG with a constitutive RhoA mutant, whether restoring microglial RhoA signaling can prevent or be used as a stopgap measure to delay MG-mediated neuroinflammation and the onset and/or progression of the disease in the 5xFAD AD mouse model, which mimics several features of AD. To bridge the gap between pre-clinical animal models and human clinical studies, we will also use an AD 3D humanized model system that recapitulates some disease features. The combined knowledge achieved by these 2 objectives will be critical to unraveling the signaling pathways underlying RhoA-mediated MG reactivity and neurodegeneration and formally proving that the regulation of RhoA activity is a novel therapeutic avenue to alleviate neuroinflammation and the burden of neurodegeneration. The international and multidisciplinary NEUROSAFE team will use state-of-the-art technologies and models to achieve these objectives through the completion of a set of complementary but not entirely interdependent activities. These include: establishing the phosphoproteomics profile of RhoA cKO and comparing it with other relevant datasets; intravital imaging of RhoA cKO; MG AAV transduction of a constitutive mutant form of RhoA to prevent and/or delay neuroinflammation and ensuing neurodegeneration in the 5xFAD AD mouse model and; to bridge the gap between human clinical studies and animal models the use of an humanized 3D model system in which we will confirm that reinstating MG RhoA activity can be used as a stopgap measure against pathological changes in AD.