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, Malmo, Sweden. Subjects. A total of 66 patients undergoing carotid endarterectomy (median age 74, range 53-89 years, 20 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 L-1 vs. 1.69 (1.09-1.99) mmol 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.