SPP1 and triple-A syndrome: Several studies have reported the role of OPN in inflammation and fibrosis regulation in human aortic aneurysm disease and animal models (Bruemmer et al., 2003; Golledge et al., 2007; Zheng et al., 2012; Fan et al., 2019), however, the structural subtype or domain of OPN that participates in or promotes the progress of AAA formation remains to be determined.