Parkinson’s Disease, Microglia, and Extracellular Matrix Remodeling

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by the selective loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and the intracellular accumulation of alpha-synuclein (α-syn) aggregates. Historically, research has focused on neuronal mechanisms; however, growing evidence indicates that the progression of neurodegeneration is influenced by changes in the brain microenvironment, particularly through the dynamic interplay between microglia and the extracellular matrix (ECM). ECM in the central nervous system is an organized network of structural proteins, glycoproteins, and proteoglycans that encases neurons and glial cells, regulating processes such as synaptic stability, neural plasticity, and intercellular signaling. In PD, the aggregation of α-syn and neuronal damage induce sustained microglial activation, which can alter ECM structure. Activated microglia release proteases, including matrix metalloproteinases and cathepsins, which can degrade critical ECM components such as collagens, laminins, and proteoglycans. This remodeling can modify synaptic architecture, regulate cellular signaling, and disrupt neuron-glia interactions, fostering an environment conducive to dopaminergic degeneration. Furthermore, ECM remodeling and microglial activation exhibit regional variability within the brain. Regions notably prone to degeneration, such as the SNpc and striatum, display significant alterations in matrix organization and inflammatory activity, while other dopaminergic regions, including the ventral tegmental area, show increased resilience. We suggest that microglia-mediated ECM remodeling serves as a mechanistic link between neuroinflammation and neuronal susceptibility in PD. This review consolidates the existing knowledge on microglial modulation of ECM dynamics during neurodegeneration, explores regional differences in these processes, and evaluates their significance as possible treatment targets.