The time course of elastin fiber degeneration in a rat aneurysm model

Abstract

Previous findings vary regarding the timing and cause of elastin fiber degeneration in the elastase-induced rat abdominal aortic aneurysm model. We examined the timing and cause of elastin fiber degeneration after elastase infusion using two different elastase infusion times. Twenty-four Sprague-Dawley rats were divided into two groups. The infrarenal abdominal aorta was infused with 15 U of elastase for 15 min (n = 12, 15-min infusion group) or 30 min (n = 12, 30-min infusion group). In each group, three rats were killed immediately and 1, 3, and 7 days after infusion, and then the aortas were excised for a histologic examination. Elastin fibers did not stain, even immediately after elastase infusion, in the 30-min infusion group. The degeneration of elastin fibers did not progress in the 15-min infusion group during the period of observation. Inflammatory cells infiltrated mainly to the adventitia near regions where the degeneration of elastin fibers spread totally through the aortic media. Elastin fibers degenerate immediately after elastase infusion and thus seem to degenerate not due to endogenous proteinases that are produced by the infiltrating cells, but due to the exogenously infused elastase itself. Inflammatory cell infiltration was thus found to be a result of the degeneration of elastin fibers in this model.

Expression of annexin II in experimental abdominal aortic aneurysms

“…Thus, we were not able to develop a model that had different levels of elastic tissue degeneration over time. Based on previous studies, there is a lack of consensus on the time course of elastin fiber degeneration in the elastase-induced AAA rat model [21,23,24].…”

Letter regarding “Interference of doxycycline pretreatment in a model of abdominal aortic aneurysms”

“…This AAA model indicates that MMPs play an "evil" role in AAA formation, and it is scientific to prevent AAA by inhibiting MMPs. The enlargement of the aorta coincides with inflammatory cell infiltration a few days after infusion in this model [4]. We speculate that aneurysm is mainly due to the expansion of the weakened wall when exposed to pulsatile blood flow, and inflammatory cell infiltration is the result of damage to the aorta by chemical corrosion rather than cause of AAA progression.…”

Degradation of elastic fiber and elevated elastase expression in long head of biceps tendinopathy

“…We have previously shown that peritendinous elastase treatment induces tendon degeneration in rats, indicating that elastase may cause changes in extracellular matrices (ECMs) . Elastase breaking down elastic fibers has been reported in various diseases, such as aneurysms and atherosclerosis . Degradation of elastin caused by activated elastase results in the release of soluble elastin‐derived peptides (EDPs).…”