Abdominal aortic aneurysms: an underestimated type of immune-mediated large vessel arteritis?

To review recent studies on the immune-mediated pathogenesis of abdominal aortic aneurysms, opening a wide field for possible new therapeutic approaches.

Immune-mediated processes including involvement of neutrophils, interferon-gamma producing T cells and proinflammatory cytokines play an important role especially in the initiation of abdominal aortic aneurysm disease. C-reactive protein was associated with aneurysm size and is possibly produced by the aneurysmal tissue itself. From the clinical perspective, both inflammatory and noninflammatory abdominal aortic aneurysms are associated with various autoimmune diseases. Preliminary data of F-FDG positron emission tomography imaging of abdominal aortic aneurysms suggest focal uptake of F-FDG within the aneurysm wall in patients with either large, rapidly expanding or symptomatic aneurysms that are prone to rupture. Thus basic research findings and clinical research focusing on the underlying immune-mediated mechanisms of abdominal aortic aneurysms will likely pave the way for new medical therapies in the future. In animal models the effects of rapamycin as an immunosuppressive agent, modulation of estrogen receptors by tamoxifen as well as gene therapy using decoy oligonucleotides binding to the transcription factor ets has already proved helpful in decreasing aneurysm expansion rates.

Pathophysiological, immunogenetical and interventional studies support the concept of abdominal aortic aneurysm as an immune-mediated process, which will help to identify more laboratory and imaging signs of development in the future. Further research will now assess the possible benefit of antiinflammatory therapeutic approaches, especially in patients with small abdominal aortic aneurysms.