Type B acute aortic dissection (AAD) spares the ascending aorta and is optimally managed by medical therapy in the absence of complications. However, patients with enhanced inflammation sometimes present with aortic enlargement, thereby facing undesirable outcomes. Thus, a better understanding of the molecular and cellular mechanisms involved in AAD-associated inflammatory processes and the requirement for a novel therapeutic approach for patients with type B AAD are unmet clinical needs. This study showed that dissection per se induced neutrophil-chemoattractant chemokine expression in the aortic tunica adventitia, possibly by mechanical injury and stretching followed by pseudolumen formation. Subsequent systemic changes in chemokine-dependent signaling caused neutrophilia and massive neutrophil accumulation in the dissected aorta, thereby leading to aortic enlargement and rupture via interleukin-6 production. Importantly, temporal and spatial dynamics of inflammatory cytokine and chemokine elevation, as well as leukocyte recruitment, were consistent between rodents and humans. Our study provides a new mechanistic insight into neutrophil-mediated adventitial inflammation after AAD and implicates CXCR2- or interleukin-6 neutralization as novel therapeutic strategies to prevent large-artery complications, including aneurysm formation and rupture, in patients with type B AAD.
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