ß-aminopropionitrile Induces Distinct Pathologies in the Ascending and Descending Thoracic Aortic Regions of Mice

The purpose of this study was to determine whether lysyl oxidase inhibition using ß-aminopropionitrile (BAPN) induced region-specific aortopathies in mice. The effects of BAPN were first characterized with regard to dose, strain, age, and sex. Subsequently, BAPN was administered to young male C57BL/6J mice. BAPN-induced aortic rupture predominantly occured or originated in the descending thoracic aorta. For mice surviving 12 weeks of BAPN administration, profound dilatation was consistently observed in the ascending region, while relatively sporadic in the descending thoracic region. Pathological features were distinct between the ascending and descending thoracic regions. Aortic pathology in the ascending region was characterized by luminal dilatation and elastic fiber disruption throughout the media. The descending thoracic region frequently had dissection with false lumen formation, macrophage infiltration, collagen deposition, and remodeling of the media and adventitia. Cells surrounding the false lumen were predominantly positive for a-smooth muscle actin. To investigate the molecular basis of the regional heterogeneity, ascending and descending thoracic aortas were harvested after one week of BAPN administration prior to the appearance of overt pathology. BAPN compromised contractile properties in both regions equivalently, while RNA sequencing demonstrated that BAPN altered transcriptomes related to extracellular matrix and cell division differentially between the two regions. In conclusion, BAPN-induced pathologies show distinct, heterogeneous features within and between ascending and descending aortic regions in young mice. Overall design: Comparative gene expression analysis of RNA-seq data for ascending and descending aortas of C57BL/6J mice administered with either water or BAPN for 1 week.