MMP9 and epilepsy: Rankin-Gee et al. (2015) find that seizure activity increases MMP proteolysis of aggrecan, which suggests a mechanism by which PNNs are degraded in epilepsy and thus contribute to the progression of the disorder. Indeed, one study found that two different strains of MMP-9 overexpressing rats displayed higher seizure susceptibility to PTZ kindling than wild type rats (Wilczynski et al., 2008). Kim et al. (2017) found upregulation of genes encoding MMP9 and 14 and ADAMTS1 in multiple brain injury and BBB leakage models as well as in resected tissue from human TLE patients (Kim et al., 2017).