title: Potential role of interleukin-18 in patients with rheumatoid arthritis-associated carotid intima-media thickness but not insulin resistance.
abstract: OBJECTIVE
  Plasma interleukin-18 (IL-18) has been reported to be associated with homeostasis model assessment of insulin resistance (HOMA-IR). It also has been described as one of the factors that, in addition to insulin resistance, may also contribute to atherosclerosis. Parameters of systemic inflammation are also significantly associated with circulating IL-18. Our objective was to investigate whether IL-18 is associated with insulin resistance and atherosclerosis in patients with rheumatoid arthritis (RA) in which accelerated atherogenesis develops.
  
  
  METHODS
  Fifty-one female RA patients and 30 female controls were enrolled in the study; 31 of them were without disease-modifying antirheumatic drug (DMARD) treatment and had a relatively short disease duration. Disease activity was assessed by Disease Activity Score (DAS) 28 index. HOMA-IR method was used to detect insulin resistance. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), fasting plasma glucose (FPG), insulin, tumor necrosis factor alpha (TNF-α), and IL-18 levels were evaluated. Also, carotid intima-media thickness (cIMT) was measured.
  
  
  RESULTS
  There were no differences between patients and the control group according to age, sex, and body mass index. ESR, CRP, insulin, FPG, HOMA-IR, TNF-α, IL-18 levels, and cIMT measurements were significantly high in the patient group. HOMA-IR and cIMT measurements were similar and high in both the DMARD and non-DMARD patient groups. HOMA-IR correlated with TNF-α (r=0.308, p=0.028), but no correlation was found between IL-18 and HOMA-IR. However, IL-18 was correlated positively with cIMT (r= 0.318, p=0.028) and negatively with BMI (r=-0.360, p=0.01).
  
  
  CONCLUSIONS
  IL-18 is associated with atherosclerosis in RA patients. However, no significant relation was found with insulin resistance. IL-18 may be a marker for early evaluation of atherosclerosis in RA patients.
authors.affiliation: Department of Internal Medicine, Süleyman Demirel University Faculty of Medicine, Isparta, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Şahin
authors.affiliation: Department of Internal Medicine, Süleyman Demirel University Faculty of Medicine, Isparta, Turkey.
authors.forename: Yunus
authors.initials: Y
authors.lastname: Ugan
authors.affiliation: Department of Internal Medicine, Süleyman Demirel University Faculty of Medicine, Isparta, Turkey.
authors.forename: Şevket Ercan
authors.initials: ŞE
authors.lastname: Tunç
authors.affiliation: Department of Internal Medicine, Adnan Menderes University Faculty of Medicine, Isparta, Turkey.
authors.forename: Şule
authors.initials: Ş
authors.lastname: Akın
authors.affiliation: Department of Internal Medicine, Süleyman Demirel University Faculty of Medicine, Isparta, Turkey.
authors.forename: Banu
authors.initials: B
authors.lastname: Köroğlu
authors.affiliation: Department of Internal Medicine Düzce University Faculty of Medicine, Düzce, Turkey.
authors.forename: Ali
authors.initials: A
authors.lastname: Kutlucan
authors.affiliation: Department of Biochemistry, Katip Çelebi University Faculty of Medicine, İzmir, Turkey.
authors.forename: Recep
authors.initials: R
authors.lastname: Sütçü
authors.affiliation: Department of Radiology, Necmettin Erbakan University Faculty of Medicine, Konya, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Yeşildağ
authors.affiliation: Department of Biochemistry, Süleyman Demirel University Faculty of Medicine, Isparta, Turkey.
authors.forename: Aysun
authors.initials: A
authors.lastname: Kılbaş
keywords: Atherosclerosis; insulin resistance; interleukin-18; rheumatoid arthritis; tumor necrosis factor alpha