MMP9 and aneurysm: Nuki et al. found that Doxycycline reduced aneurysm incidence, particularly in MMP-9 knockout mice (Nuki et al., 2009), while Makino et al. showed that minocycline and Doxycycline reduced rupture rates in hypertensive mice with elastase-induced aneurysms (Makino et al., 2012).