The Neuroimmune Landscape of the Lysosomal Storage Disorder Sanfilippo Syndrome.

Lysosomal storage disorders (LSDs) such as Sanfilippo syndrome (Mucopolysaccharidosis type III) are characterized by impaired lysosomal degradation due to inherited in lysosomal proteins. This dysfunction leads to the accumulation of undegraded substrates, such as heparan sulfate, ultimately leading to progressive neuroinflammation and neurodegeneration. Despite well-defined genetic causes, no disease-modifying therapies exist for Sanfilippo syndrome. While microglia, the brain's resident immune cells, can play both protective and pathogenic roles, the contribution of neuroinflammation to LSD pathology remains underexplored. This review examines the contribution of neuroinflammation to Sanfilippo syndrome, emphasizing emerging mechanisms involving TLR4 signaling, inflammasome activation, the cGAS-STING pathway, and lysosomal biogenesis regulators such as TFE family transcription factors. We also discuss the potential of cellular therapies to modulate neuroimmune responses and offer new therapeutic avenues. By integrating insights from neuroimmunology and lysosomal biology, we aim to identify shared mechanisms and therapeutic targets across Sanfilippo syndrome and related LSDs.