Objective: It is suggested that chronic infections are risk factors for cardiovascular disease, and a positive correlation between periodontitis and stroke has been established. Recently, we reported that the leukotoxin of the periodontitis-associated bacterium A. actinomycetemcomitans (Aa) induces abundant secretion of IL-1b from macrophages. Here the prevalence of systemic antibodies to Aa-leukotoxin in stroke subjects and controls were analysed and compared. Methods: This study was an incident case-control study nested within the Västerbotten Intervention Program and Northern Sweden MONICA cohorts. All strokes were defined according to strict WHO criteria. Up to year 2000, 74,000 subjects had participated in one of the surveys. For this study 273 cases and 546 matched controls were extracted. The survey was performed before the stroke event. Antibodies to Aa-leukotoxin were analyzed in a bioassay employing HL-60 cells exposed to leukotoxin. A sample that inhibited ³50% of leukotoxin-induced cell-lysis was considered positive. Conditional logistic regression was used to investigate the association between antibodies and stroke. Univariate analysis including antibodies (pos/neg) was carried out. To adjust for possible confounders multiple regression analyses were used. The results are presented as odds ratios (OR) and 95% confidence intervals (CI). Results: Antibodies to Aa-leukotoxin were detected in 17% of the subjects. Prevalence of antibodies was negatively associated with a future stroke (OR=0.557, CI: 0.363-0.854). Females with antibodies had decreased risk for stroke (OR=0.281, CI: 0.134-0.590), while no statistically significant association was seen for men (OR=0.884, CI: 0.517-1.512). Adjusting for the possible confounders BMI, smoking, cholesterol, diabetes, hypertension and educational level verified the results. The association between antibodies and a future stroke did not vary substantially depending on type of stroke. Conclusion: Immunoreacitivity to Aa-leukotoxin correlates negatively with a future stroke. Further studies are needed to explain the mechanisms behind, as well as the biological relevance of this unexpected finding.

Back to the Microbiology / Immunology and Infection Control Program
Back to the IADR/AADR/CADR 82nd General Session (March 10-13, 2004)

Top Level Search