Galectin-3 Inhibition Prevents Excitatory Synapse Loss in Murine Neuroinflammation Models

Microglial activation is a hallmark of the aging brain and various neurodegenerative pathologies, where these resident macrophages transition into a pro-inflammatory state often referred to as primed microglia (a hypersensitive phenotype characterized by a conserved transcriptional signature involving lysosomal and phagosomal pathways) [1, 2]. While moderate activation can be neuroprotective by clearing protein aggregates, chronic neuroinflammation frequently shifts this balance toward a neurotoxic phenotype that accelerates disease progression [3, 4]. A meta-analysis of 905 patients confirmed that Galectin-3 levels are significantly elevated in individuals with Alzheimer's and Parkinson's diseases (standardized mean difference 0.70; 95% confidence interval, 0.28 to 1.13; p = 0.001) [5, 6]. These reactive states are linked to aberrant synaptic pruning, where microglia erroneously engulf healthy neuronal connections via pathways such as the C1q/C3 complement cascade, leading to the cognitive deficits seen in clinical practice [4, 7]. New research using a lipopolysaccharide-induced neuroinflammation model (0.5 mg/kg for 7 days) demonstrates that Galectin-3 specifically mediates the selective elimination of excitatory synapses in the hippocampal CA1 region, directly impairing gamma power and cognitive performance [8]. For practicing physicians, this study identifies a specific molecular target that drives the synaptic loss underlying dementia, raising the possibility of future therapies designed to halt cognitive decline by preventing microglia from consuming healthy synapses.