In the AD context, MMP-2 has been reported to participate in the degradation of the blood–brain barrier (BBB), facilitating the infiltration of inflammatory cells (Candelario-Jalil et al., 2011), while MMP-9 was pointed to accentuate the neurobehavioral deficits in a mouse model of AD (Ringland et al., 2021). Here, MMP9 is linked to Alzheimer disease.