Matrix metalloproteinase-9 leads to blood–brain barrier leakage in mice with eosinophilic meningoencephalitis caused by Angiostrongylus cantonensis

Blood-brain barrier (BBB) disruption is associated with tight junction protein degradation, basal membrane disruption, and astrocyte damage. This study aims to investigate the role of matrix metalloproteinase (MMP)-9 in BBB disruption during Angiostrongylus cantonensis infection. We used mice infected with A. cantonensis, in which parasite-induced eosinophilia and inflammation might induce MMP-9 elevation. MMP-9 could cause claudin-5 degradation in endothelium tight junction, collagen type IV degradation in basal membranes, and S100B degradation in astrocytes of wild-type mice. BBB permeability was significantly attenuated in MMP-9 knockout mice than in wild-type mice in angiostrongyliasis meningoencephalitis. Immune cell aggregates were also more attenuated in the brains of MMP-9 knockout mice than in the brains of wild-type mice. Results suggest that MMP-9 activities are significant in BBB disruption in angiostrongyliasis meningoencephalitis. This study improves understanding of molecular mechanisms that underlie brain invasion by A. cantonensis, which is a key step in the pathogenesis of meningoencephalitis, and can offer a new strategy to reduce mortality.