Interleukin-1 receptor antagonist is detectable in human carotid artery plaques and is related to triglyceride levels and Chlamydia pneumoniae IgA antibodies.

OBJECTIVES: To investigate whether the interleukin-1 receptor antagonist (Il-1ra) and interleukin-1beta (Il-1beta) can be detected in human carotid artery tissue, and whether their presence is related to evidence of Chlamydia pneumoniae infection, risk factors for atherosclerosis, and clinical data. SETTING: Departments of Vascular Diseases and Surgical Pathophysiology, University Hospital, Malmö, Sweden. SUBJECTS: A total of 66 patients undergoing carotid endarterectomy (median age 74, range 53-89 years, 26 women). Il-1beta and Il-1ra were studied in carotid artery plaques and in Il-1ra in serum. RESULTS: Interleukin-1 receptor antagonist was detected in mononuclear cells in plaques from 37/66 (56%) patients. Patients with Il-1ra in plaques showed higher [2.04 (1.70-3.14) mmol x L(-1) vs. 1.69 (1.09-1.99) mmol x L(-1); P < 0.05] serum(s-)triglyceride(tg) levels, and a higher frequency of IgA seropositivity for C. pneumoniae (76% vs. 52%; P < 0.05) than those without. S-Il-1ra levels correlated with s-tg levels (r=0.38; P=0.047). There were no differences between patients with and without Il-1ra in plaques concerning s-Il-1ra, blood(b-)haemoglobin or leucocyte count, s-cholesterol, b-glucose, blood pressure, IgG seropositivity for C. pneumoniae, prevalence of neurological symptoms preceding operation, smoking, or diabetes mellitus. There were no differences in frequency of Il-1ra in plaques or in s-Il-1ra levels between patients with symptomatic and asymptomatic stenosis, between smokers and nonsmokers, or between diabetic and nondiabetic patients. Il-1beta was not detected in plaques in the current study. CONCLUSION: Interleukin-1 receptor antagonist can be detected in human atherosclerotic carotid artery plaques, and is related to s-triglyceride levels and IgA seropositivity for C. pneumoniae, but not to prevalence of neurological symptoms related to embolization.