Lysophospholipids in Synucleinopathies: A Conceptual Framework Linking Proteostasis and Neuroinflammatory Signaling.

Synucleinopathies, including Parkinson's disease and dementia with Lewy bodies, are characterized by progressive α-synuclein (α-Syn) aggregation accompanied by chronic neuroinflammatory changes. However, the mechanistic relationship between disrupted proteostasis and inflammatory signaling remains incompletely defined and may vary across disease stages and clinical subtypes. Lysophospholipids (LPLs) are bioactive lipids derived from membrane phospholipids that participate in diverse cellular processes. These functions are primarily mediated through G protein-coupled receptor (GPCR) signaling, but may also involve direct effects on membrane organization and biophysical properties. In addition to receptor-mediated pathways, the surrounding lipid environment may influence protein behavior, although its role in neurodegenerative processes remains to be fully elucidated. Within this framework, LPLs can be considered not only as signaling molecules but also as modulators of the cellular environment in which proteostasis and inflammatory responses occur. In this review, we adopt a lipid-centered perspective in which LPLs occupy an interface between lipid signaling, protein aggregation, and neuroinflammation. Rather than acting as a single initiating factor, altered lipid metabolism is likely to contribute through multiple interconnected pathways. Although current evidence is largely derived from preclinical studies, it supports a role for lipid-related mechanisms, particularly in early stages of synucleinopathy.