MAPT and Alzheimer disease: The abundance of gingipains correlates with the tau protein load in AD brain autopsies (Dominy et al., 2019), and gingipains can cleave tau in vitro (Dominy et al., 2019), an activity that might contribute to aberrant tau phosphorylation and accumulation of insoluble tau forms in AD (Kovacech and Novak, 2010).