Levels and Determinants of Inflammatory Biomarkers in a Swiss Population-Based Sample (CoLaus Study)

et al. (2011) Levels and Determinants of Inflammatory Biomarkers in a Swiss Population- Based Sample (CoLaus Study). PLoS ONE 6(6): e21002. doi:10.1371/journal.pone.0021002 Levels and Determinants of Inflammatory Biomarkers in a Swiss Population-Based Sample (CoLaus Study) Pedro Marques-Vidal 0 Murielle Bochud 0 Franc ois Bastardot 0 Thomas Lu scher 0 Franc ois Ferrero 0 Jean-Michel Gaspoz 0 Fred Paccaud 0 Adrian Urwyler 0 Roland von Ka nel 0 Christoph Hock 0 Ge rard 0 Waeber 0 Martin Preisig 0 Peter Vollenweider 0 Massimo Federici, University of Tor Vergata, Italy 0 1 Institute of Social and Preventive Medicine (IUMSP), CHUV and Faculty of Biology and Medicine , Lausanne , Switzerland , 2 Department of Medicine, Internal Medicine, CHUV and Faculty of Biology and Medicine , Lausanne , Switzerland , 3 Department of Medicine, University of Zu rich, Zu rich, Switzerland, 4 Department of Psychiatry, University of Geneva , Geneva , Switzerland , 5 Department of Community Medicine, University of Geneva , Geneva, Switzerland, 6 Cytolab, Da llikon, Switzerland , 7 Division of Psychosomatic Medicine, Bern University Hospital Inselspital, and University of Bern , Bern , Switzerland , 8 Department of Psychiatry, University Hospital Zu rich, Z u rich, Switzerland, 9 Department of Psychiatry, CHUV , Lausanne , Switzerland Objective: to assess the levels and determinants of interleukin (IL)-1b, IL-6, tumour necrosis factor (TNF)-a and C-reactive protein (CRP) in a healthy Caucasian population. Methods: population sample of 2884 men and 3201 women aged 35 to 75. IL-1b, IL-6 and TNF-a were assessed by a multiplexed particle-based flow cytometric assay and CRP by an immunometric assay. Results: Spearman rank correlations between duplicate cytokine measurements (N = 80) ranged between 0.89 and 0.96; intra-class correlation coefficients ranged between 0.94 and 0.97, indicating good reproducibility. Among the 6085 participants, 2289 (37.6%), 451 (7.4%) and 43 (0.7%) had IL-1b, IL-6 and TNF-a levels below detection limits, respectively. Median (interquartile range) for participants with detectable values were 1.17 (0.48-3.90) pg/ml for IL-1b; 1.47 (0.71-3.53) pg/ml for IL-6; 2.89 (1.82-4.53) pg/ml for TNF-a and 1.3 (0.6-2.7) ng/ml for CRP. On multivariate analysis, greater age was the only factor inversely associated with IL-1b levels. Male sex, increased BMI and smoking were associated with greater IL-6 levels, while no relationship was found for age and leisure-time PA. Male sex, greater age, increased BMI and current smoking were associated with greater TNF-a levels, while no relationship was found with leisure-time PA. CRP levels were positively related to age, BMI and smoking, and inversely to male sex and physical activity. Conclusion: Population-based levels of several cytokines were established. Increased age and BMI, and to a lesser degree sex and smoking, significantly and differentially impact cytokine levels, while leisure-time physical activity has little effect. - Funding: The CoLaus study was supported by research grants from the Swiss National Science Foundation (grant no: 33CSCO-122661) from GlaxoSmithKline and the Faculty of Biology and Medicine of Lausanne, Switzerland. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Proinflammatory cytokines, such as interleukin (IL)-1b, IL-6 and tumor necrosis factor (TNF)-a and the acute phase reactant C-reactive protein (CRP) have important effects in inflammation and atherosclerosis. Elevated levels of these inflammatory biomarkers have been associated with an increased risk of developing incident coronary heart disease [13]. Several studies have shown that cytokine levels can be mediated by several lifestyle factors such as smoking [4] and physical activity [46]. Still, contrary to the considerable data regarding the contribution of cytokines to atherothrombotic diseases, little information is available regarding the distribution of cytokine levels and their determinants within a population-based sample [7,8]. Hence, we used the data from the large, population-based CoLaus study to 1) assess cytokine levels in an apparently healthy, population-based Caucasian adult sample and 2) assess the independent effects of sex, age, BMI, smoking and physical activity on cytokine levels. To our knowledge, this is currently the largest population study that has cytokines levels measured. Ethics statement The CoLaus Study was approved by the Institutional Ethics Committee of the University of Lausanne (decision 19 February 2003, protocol number 16/03). Written informed consent was obtained from all participants. Recruitment The CoLaus Study is a cross-sectional study aimed at assessing the prevalence of CVD risk factors as the molecular determinants of CVD in the Caucasian population of Lausanne, Switzerland, a town of 117,161 inhabitants, of which 79,420 are of Swiss nationality. The sampling procedure of the CoLaus Study has previously been described [9]. Recruitment began in June 2003 and ended in May 2006. Participation rate was 41%. All participants attended the outpatient clinic of the University Hospital of Lausanne in the morning after an overnight fast. Data were collected by trained field interviewers in a single visit lasting about 60 min. No information regarding revenues or social deprivation was collected. Lifestyle and clinical data Participants were classified as never, current, or former smokers. A participant was considered as physically active if he/she reported practicing at least 2 hours of leisure-time physical activity per week. Body weight and height were measured with participants standing without shoes in light indoor clothes. Body weight was measured in kilograms to the nearest 100 g using a SecaH scale, regularly calibrated. Height was measured to the nearest 5 mm using a SecaH height gauge. Overweight was defined as a BMI $25 and ,30 kg.m22; obesity was defined as a BMI $30 kg.m22. Cytokine measurement Venous blood samples (50 mL) were drawn in the fasting state and allowed to clot. Serum was preferred to plasma as it has been shown that different anticoagulants may affect absolute cytokine levels differently [10,11]. High sensitive CRP (hs-CRP) was assessed by immunoassay and latex HS (IMMULITE 1000High, Diagnostic Products Corporation, LA, CA, USA) with maximum intra- and interbatch coefficients of variation of 1.3% and 4.6%, respectively. Serum samples were kept at 280uC before assessment of IL-1b, IL-6, and TNF-a and sent in dry ice to the laboratory. Levels of these cytokines were measured using a multiplexed particle-based flow cytometric cytokine assay [12]. This methodology yields cytokine concentrations which correlate well with those obtained by other methods such as ELISA [13] (for a review, see [14]). Milliplex kits were purchased from Millipore (Zug, Switzerland). The procedures closely followed the manuf (...truncated)