AIM2 levels and DNA-triggered inflammasome response are increased in peripheral leukocytes of patients with abdominal aortic aneurysm.

Objective And Design: Abdominal aortic aneurysm (AAA) is heavily infiltrated with leukocytes, expressing the DNA sensor absent in melanoma 2 (AIM2) and other inflammasome components.

Methods: Using multicolour flow cytometry, we here compared the expression of the inflammasome components AIM2, NLRP3, and ASC in different peripheral immune cells derived from AAA patients with those from non-AAA patients in a case-control study. In parallel, peripheral blood mononuclear cells (PBMC) of AAA patients and controls were stimulated in vitro with poly-dA:dT or lipopolysaccharide (LPS) to analyze inflammasome activation.

Results: AIM2 expression was significantly increased in peripheral granulocytes (P = 0.026), monocytes (P = 0.007), B lymphocytes (P < 0.0001), and T lymphocytes (P = 0.004) of AAA patients. Expression of other inflammasome components did not differ between the groups. Following in vitro stimulation with foreign DNA, PBMC derived from AAA patients released significantly more IL-1β (P = 0.022) into the supernatant than PBMC from control patients. In contrast, IL-1β release upon LPS stimulation did not differ between the PBMC groups.

Conclusion: The data indicate the increased activation of an AIM2 inflammasome in peripheral immune cells of AAA patients and point to a systemic AIM2-associated immune response to AAA.