Microglial advances in Parkinson’s disease

Microglia perform the function of CNS macrophages and act as the primary immune cells in the brain. They surveil the environment, phagocytose cellular debris, maintain homeostasis and respond to tissue damage. While under physiological conditions they play a role in supporting neurons, activated microglia participate directly in the degeneration of neurons in the substantia nigra, as the hallmark of the Parkinsons disease (PD). Their detrimental effects result from direct phagocytosis of dopaminergic neurons as well as via neuroinflammation and release of toxic reactive oxygen and nitrogen species. This pathological shift is driven by a complex interplay of genetic predispositions, such as LRRK2 and GBA mutations, and environmental triggers like toxins and gut dysbiosis.A central mechanism of this neurodegeneration involves extracellular α-synuclein acting as a danger signal (DAMP), which activates microglial Toll-like receptors (e.g., TLR2) to initiate a severe inflammatory cascade. Furthermore, the extreme biophysical stability of aggregated α-synuclein overwhelms the microglial endolysosomal network, leading to lysosomal failure, “frustrated phagocytosis,” and the active propagation of the disease via exosomal shedding. Relieving this maladaptive chronic neuroinflammation is a primary therapeutic goal. Modern strategies aim to break this vicious cycle through precise interventions like NLRP3 inflammasome inhibition and autophagy enhancement. Concurrently, advanced fluid biomarkers, such as seed amplification assays (SAA), alongside multidimensional neuroimaging techniques (PET, SPECT, MRI), are proving crucial for detecting these early microglial and pathological changes to guide personalized, disease-modifying therapies of PD.