Immune-response against Streptococcus pyogenes in the development of abdominal aortic aneurysm – A population-based case-control study

Abstract

In a population-based case-control study the association between antibodies to Streptococcus pyogenes antigens and the development of abdominal aortic aneurysm (AAA) was analysed. Forty-two patients with screening-detected AAA were compared to 100 age- and sex matched controls with normal aortas. Antibodies against three recently characterized cell wall-attached proteins of S. pyogenes (SclA, SclB and GRAB) were analysed in plasma samples obtained at screening (current), and in samples obtained from a study conducted 12 years previously on the same population (historical). Historical antibody levels against the S. pyogenes antigen GRAB were significantly higher in AAA patients compared with controls (0.25 vs 0.17, p = 0.021). A similar trend was observed in current GRAB antibody levels (0.23 vs 0.17, p = 0.072). GRAB-antibody levels at age 60 years retained the association with AAA in a logistic regression model after adjustment for a history of atherosclerosis (OR 20.2, p = 0.022), current smoking (OR 21.4, p = 0.025) and family history of AAA (OR 12.9, p = 0.053). Current and historical antibody levels against SclA and SclB in AAA patients were similar to those in controls. The results indicate that the immune response against S. pyogenes protein GRAB may be involved in the pathogenesis of AAA.