Abstract Body: Background: Environmental pollutants including particulate matter (PM) increase the morbidity and mortality for cardiovascular disorders. Recent study analyzing UK biobank datasets suggested that exposure to PM2.5 or PM10 was associated with the increased risk for abdominal aortic aneurysms (AAA). However, it has not been studied whether PM exposure alters experimental AAA formation and progression.
Methods: Experimental AAAs were induced in 9-10 weeks old male C57BL/6J mice via porcine pancreatic elastase aortic wall painting procedure. Three days following AAA induction, urban particulate matter (NIST1648a, mean particulate diameter (d50): 5.87 µm, 100 µg/mouse/day) or vehicle (saline) was daily administered via intranasal installation for 11 days. Influence on experimental AAAs was assessed via serial measurements of infrarenal aortic diameter via ultrasonography and histopathological analysis at sacrifice.
Results: In ultrasound imaging, no difference was noted in the baseline aortic diameter (either prior to AAA induction or PM exposure). However, PM exposure led to marked aneurysm enlargement on days 7 and 14 following AAA induction as compared to vehicle exposure. On histological analysis, PM exposure accelerated medial elastin degradation and smooth muscle cell loss as compared to vehicle exposure. Aortic accumulation of macrophages and lymphocytes were more remarkable in PM-, than those in vehicle-, exposed AAA mice. Additionally, PM exposure also substantially increased the density of CD31-positive neovessels in aneurysmal lesion as compared to vehicle exposure.
Conclusion: Particulate matter exposure worsens experimental AAA progression in associated with augmented aneurysmal wall inflammation.