Adverse reactions during endovascular treatment of aortic aneurysms may be triggered by interleukin 6 release from the thrombotic content

Purpose: It has been shown that endovascular aortic aneurysm repair might induce a significant inflammatory response, mainly involving tumor necrosis factor (TNF-alpha) release. This study determined in vitro whether these inflammatory responses could depend on white blood cell (WBC) activation caused by the aneurysmal mural thrombus. Methods: Mural thrombus specimens obtained from 10 different aortic aneurysms were weighed, homogenized, and assayed for interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), TNF-alpha, and soluble TNF receptor (sTNFRI). Results:Only high amounts of IL-6 (mean, 2973 pg/mL) were found. In contrast, after the addition of healthy donor WBCs to the thrombus mass supernatants, elevated levels of TNF-alpha (mean, 523 pg/mL) were seen. Theoretically, WBCs were stimulated by IL-6, resulting in TNF-a release. In additional experiments, it was proven that stimulated WBCs, induced by thrombus mass supernatants, synthesize TNF-alpha (mean, 796 pg/mL), and monoclonal antibodies against IL-6, prevented such TNF-alpha production (mean, 62 pg/mL). Conclusion: The biologic responses during endovascular repair may be explained by a release of IL-6 from the aneurysmal thrombus, causing WBC stimulation and production of TNF-alpha. More complex processes cannot be excluded, but the present findings suggest that restrictions of manipulations within the aneurysm may be advisable.