- Email: [email protected]
Intravenous catheters induce a local inflammatory response
Cytokine xxx (xxxx) xxx–xxx
Contents lists available at ScienceDirect
Cytokine journal homepage: www.elsevier.com/locate/cytokine
Intravenous catheters induce a local inflammatory response Katherine Chabotb, Marie-Eve Lavoiea,b, Jean-Philippe Bastardc,d,e, Rémi Rabasa-Lhoreta,b,
⁎
a
Department of Nutrition, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada Institut de recherches cliniques de Montréal (affiliated to the Université de Montréal), 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada AP-HP, Hôpital Tenon, UF Bio-marqueurs Inflammatoires et Métaboliques, Service de Biochimie et Hormonologie, Paris F75020, France d Sorbonne Universities UPMC Paris 6, UMR_S 938 CDR-Saint-Antoine, F-75012 Paris, France e University Hospital ICAN Institute, Paris, France b c
A R T I C LE I N FO
A B S T R A C T
Keywords: Inflammation IL-6 CRP Intravenous catheter
Aim: Chronic inflammation has been associated to the development of cardiometabolic dysfunctions. The use of an intravenous (IV) catheter is highly recommended for physiology testing. Yet, the presence of an IV catheter triggers local inflammation that does not reflect systemic inflammatory status. The aim of this study was to assess the effect of an IV catheter on serum concentrations of IL-6, IL-8 and hsCRP in a fasting state and after a high-fat meal known to trigger low-grade inflammation. Methods: Twenty-two healthy subjects (7 men, 15 women) were included in this study. The trial included 2 visits. After an overnight fast, a venous catheter was inserted into an antecubital vein. A first blood sample was collected through this catheter at T = 0 min. On each visit, participants were requested either to drink only water for the whole duration of the test (WO test), or to consume a high-fat meal (HFM). Blood samples were collected through the catheter at T60, T120, T180 and T300 min. Additional venous punctures were performed on the contralateral arm at T180 and T300 min. Serum inflammatory mediators were measured at each time point of both interventions. Results: When serum was collected by venous punctures, IL-6 concentrations remained unchanged during both WO and HFM tests (Ptime = 0.15 and Ptime = 0.23, respectively), whereas the concentrations increased progressively over time when serum was collected through the catheter (Ptime < 0.001). The high-fat meal had no additional effect on IL-6 levels (Pmeal = 0.27) neither in serum collected by venous puncture nor in serum collected through the catheter. Serum IL-8 and hsCRP concentrations did not vary over time, and were influenced neither by the meal type nor by the blood collection method. Conclusion: The insertion of an indwelling catheter is associated with a local inflammatory response possibly mediated by IL-6 but not IL-8. This inflammatory response was not enhanced by a pro-inflammatory high-fat meal.
1. Introduction
Chronic low-grade inflammation has been associated to the development of cardiometabolic dysfunctions such as insulin resistance, type 2 diabetes and atherosclerosis [3]. Elevated blood concentrations of inflammatory molecules and biomarkers (e.g. interleukin [IL]-6, C-reactive protein [CRP]) predict future development of insulin resistance and type 2 diabetes [4]. On the other hand, cytokines are regularly used to monitor the activity of inflammatory conditions such as arthritis and Crohn’s disease and to assess effectiveness of their treatment [5,6]. In research facilities, the use of an intravenous (IV) catheter is highly recommended for physiology testing in order to provide continuous venous access and to avoid multiple venous punctures [7]. Yet, it has been suggested that the presence of an IV catheter triggers a local
Inflammation is a protective host response intended to eliminate the cause of cell injury and to restore homeostasis [1]. It is induced by exogenous (e.g. microbes, allergens, foreign bodies) and/or endogenous stimuli (e.g. damaged vascular endothelium, monosodium urate crystals, auto anti-bodies), and is mediated by inflammatory molecules such as vasoactive amines, arachidonic acid metabolites, cytokines and chemokines [1,2]. The inflammatory response can be subdivided into acute or chronic: while acute inflammation has a rapid onset and a short duration, chronic inflammation has a more insidious development [1].
Abbreviations: BMI, body mass index; CRP, C-reactive protein; HFM, high fat meal; IL, interleukin; IV, intravenous; LBM, lean body mass; TNF, tumor necrosis factor; WO, water only ⁎ Corresponding author at: Institut de recherches cliniques de Montréal (IRCM), 110, avenue Des Pins Ouest, Montréal, Québec H2W 1R7, Canada. E-mail address: [email protected] (R. Rabasa-Lhoret). https://doi.org/10.1016/j.cyto.2018.05.034 Received 4 November 2017; Received in revised form 13 April 2018; Accepted 29 May 2018 1043-4666/ © 2018 Elsevier Ltd. All rights reserved.
Please cite this article as: Chabot, K., Cytokine (2018), https://doi.org/10.1016/j.cyto.2018.05.034
Cytokine xxx (xxxx) xxx–xxx
K. Chabot et al.
test). Subsequent blood samples were collected through the catheter at T60, T120, T180 and T300 min. Additional venous punctures were performed on the contralateral arm at T180 and T300 min. Subjects who were randomized to the water-only test on their first visit would be requested to consume the high-fat meal on their next visit, and vice versa. The two interventions were separated by 1 to 4 weeks. For women subjects specifically, the interventions were separated by exactly 1 month such that both test occurred at the same phase of their menstrual cycle (i.e. 10 days following the onset of menses). All subjects were asked to standardize their lifestyle for the 2 days preceding each test to minimize the confounding effect of variations in diet and/or exercise habits on inflammation.
inflammatory reaction at the insertion site, and that this local inflammation detectable in blood samples does not reflect systemic inflammatory status [8–11]. To date, studies have mainly focused on the effect of the catheter on IL-6 concentrations, except for Haack et al. who also evaluated plasma concentrations of tumor necrosis factor α (TNFα), but showed no significant effect of the catheter on this cytokine [9]. Nevertheless, these few studies suggest that blood collection through an indwelling catheter could introduce a significant bias in the assessment of inflammation. The aim of this study is thus to assess the effect of an IV catheter on serum concentrations of IL-6, IL-8 and hsCRP in a fasting state and after a high-fat meal known to trigger low-grade systemic inflammation [12]. We hypothesize that the catheter will increase serum concentrations of inflammatory mediators locally, but not systemically, and that a highfat meal will have no additional effect on this local inflammatory response.
2.4. High-fat test meal The high-fat meal consisted of 50 g of cheddar cheese, one slice (30 g) of bread and a milkshake made with 250 mL of 3.25% fat milk, 250 mL of vanilla ice cream, 100 mL of eggs and 15 mL of cocoa powder. This meal provided 867 kcal and its macronutrients composition was as follows: 17% of total energy intake from proteins, 31% from carbohydrates and 52% from lipids.
2. Subjects and methods 2.1. Subjects Twenty-two healthy subjects (7 men, 15 women), all students or staff of the Institut de Recherches Cliniques de Montreal (IRCM), were included in this study. Subjects were included if they met the following criteria: age 18–50 years; body mass index (BMI) 18–27 kg/m2; nonsmoking; stable weight ( ± 3 kg) for 3 months; good venous access. The exclusion criteria were as follows: (1) type 1 or type 2 diabetes; (2) hypertension; (3) dyslipidemia; (4) acute medical event in the previous 4 months; (5) symptomatic infectious event in the previous month; (6) history of chronic inflammatory disease or cancer; (7) use of drugs that may modulate inflammation (unless dose was stable for ≥ 1 month); (8) any unstable chronic condition (e.g. untreated hypothyroidism); (9) lactose intolerance, or intolerance to any food included in the test meal; (10) pregnant or breastfeeding women. This randomized, crossover intervention study was approved by the IRCM’s ethics committee. Subjects were recruited and examined by our research team from 2010 to 2013. All enrolled subjects read and signed a consent form prior to the beginning of proceedings.
2.5. Blood analysis Serum inflammatory mediators IL-6 and IL-8 were measured at each time point of both interventions using commercially available ELISA kits (Quantikine, Minneapolis, MN, USA). Serum high-sensitive CRP (hsCRP) was measured by an automated analyzer (COBAS INTEGRA® 400, Roche Diagnostic, Montreal, Canada) at T0, T180 and T300 min of each intervention. 2.6. Statistical analysis The D’Agostino and Pearson omnibus normality test was used to evaluate the distribution of all parameters. Skewed variables were analyzed using nonparametric tests. We performed three-way ANOVAs using time (Ptime), meal type (Pmeal) and blood collection method (Pmethod) as independent variables and serum IL-6, IL-8 or hsCRP as dependent variables. In case of significant interaction, an additional Wilcoxon rank test or a Friedman test was performed, as appropriate. Dunn's multiple comparison tests were used in case of a significant Pvalue, when appropriate. All statistical analyses were performed using SPSS Statistics Version 24.0 for Windows (SPSS Inc., Chicago, IL, USA), and results were considered statistically significant when P < 0.05.
2.2. Preliminary characterization On their first visit, which took place 1 to 4 weeks before the main trial, all participants underwent a medical examination to determine their eligibility. Blood pressure and anthropometric parameters were also measured. Blood pressure was determined as the average of three readings in the left arm after subjects rested for 10 min using a Spot Vital Signs® Device (Welch Allyn Inc., San Diego, CA). Body weight and standing height were measured using a calibrated electronic scale (Balances Industrielles Montreal Inc., Montreal, Canada) and a wall stadiometer (Perspective Enterprises, Portage, MI, USA), respectively. Body mass index (BMI) was calculated as follows: BMI (kg/m2) = [body weight/height2]. Waist circumference was measured with a non-extendable linear tape measure at the top of the iliac crest. Lean body mass (kg), fat mass (kg), and body fat percentage were measured by dual energy X-ray absorptiometry using a Lunar iDXA Podigy system (General Electric Lunar Corporation, Madison, WI, USA).
3. Results Anthropometric and hemodynamic characteristics of the study subjects are presented in Table 1. Fig. 1 depicts the 5-hour time course of IL-6 concentrations in serum collected by venous punctures and Table 1 Baseline anthropometric and hemodynamic characteristics of study subjects. Variables n Sex, F:M Age, y BMI, kg/m2 Waist circumference, cm Fat mass, kg LBM, kg Body fat, % Systolic blood pressure, mm Hg Diastolic blood pressure, mm Hg
2.3. Study design The main trial included two visits at our research facility. After a 12hour overnight fast, a venous catheter made of fluorinated ethylene propylene (Smiths Medical Jelco®, 20G x 1¼ inch) was inserted into an antecubital vein. A first blood sample was collected through the catheter in Vacutainer® tubes at T = 0 min (T0). Participants were then requested either to drink only water for the whole duration of the test, or to consume a high-fat meal within 20 min (water allowed during the
27.4 23.3 80.8 16.9 45.8 26.1 108.2 69.7
22 15:7 ± ± ± ± ± ± ± ±
5.4 3.1 9.2 5.9 10.0 8.5 10.0 7.1
Data are expressed as mean ± SD. Abbreviations: F, female; M, male; BMI, body mass index; LBM, lean body mass. 2
Cytokine xxx (xxxx) xxx–xxx
K. Chabot et al.
Fig. 1. Time course of interleukin-6 (IL-6) concentrations in serum collected by venous punctures and through an indwelling catheter during a water-only (WO) test and after a high-fat meal (HFM). Data are presented as mean ± SEM. test. * p < 0.05; ** p < 0.01; *** p < 0. 001.
on inflammation, and (2) that this inflammatory response is localized rather than systemic. As expected, serum CRP concentrations were unchanged in our study. Indeed, CRP is produced almost exclusively by hepatocytes, mainly under transcriptional control in response to IL-6, IL-1 and TNFalpha. Its synthesis begins 4–6 h after stimulation and its maximum serum concentrations are reached usually in about 48 h [13,14]. In our study, serum IL-6 concentrations were increased locally, but not at the systemic level which could explain a lack of stimulation of hepatocytes to produce CRP. Interleukin 8 remained also unchanged during the test. However, unlike CRP, many different cell types, including dermal fibroblasts, keratinocytes, endothelial cells and platelets [15], have the ability to express and secrete IL-8. This chemokine is produced upon inflammation, infection and trauma, for example. Some evidences indicate that a catheter indwelling within a vein exerts constant pressure upon the endothelium, which can promote an inflammatory response. Recently, Weiss et al. showed that mechanical compression of in-vitro cultured endothelial cells increases the release of IL-8 by these cells [16]. However, we did not observe any effect of the indwelling catheter on the IL-8 levels. Similarly, the alteration of the cutaneous barrier following the insertion of a catheter did not seem to induce the secretion of IL-8 in our study. Interleukin-1 and TNF-alpha are considered the most important stimuli to induce IL-8 secretion [14], and the peak increase in IL-8 concentrations is observed 2 h after stimulation [15]. Unfortunately, serum concentrations of IL-1 and TNF-alpha have not been measured in this study, therefore limiting our interpretation of the results. Nevertheless, a previous study did not demonstrate a local increase in secretion of post-catheter TNF-alpha [9]. Moreover, the fact that IL-8 did not increase during the test is not in favor of a local increase in either TNF-alpha or IL-1. There is growing body of literature on the role played by platelets in inflammation. Platelets patrol the blood vasculature for endothelial damages and the presence of intravascular pathogens. Through their interactions with other cell types, including monocytes, neutrophils and
through an indwelling catheter, during a water-only (WO) test and after a high-fat meal (HFM). Mean concentrations of IL-6 were significantly higher in serum collected before the HFM as compared to serum collected at the beginning of the WO test (0.65 ± 0.92 pg/mL vs 0.30 ± 0.34 pg/mL, respectively, P = 0.02). At that time point, all samples were collected through an indwelling catheter. There was a significant interaction between time and blood collection method (P = 0.015). IL-6 concentrations remained unchanged during both WO and HFM tests (Ptime = 0.15 and Ptime = 0.23, respectively) when serum was collected by venous punctures, whereas the concentrations increased progressively over time to reach levels as high as 8-times the baseline concentrations when serum was collected through the catheter (Ptime < 0.001). Except for the significant difference in baseline IL-6 concentrations, the high-fat meal had no significant effect on IL-6 levels (Pmeal = 0.27) neither in serum collected by venous puncture nor in serum collected through an indwelling catheter. Figs. 2 and 3 show the time courses of IL-8 and hsCRP concentrations, respectively. Serum IL-8 concentrations did not vary over time (Ptime = 0.77), and were influenced neither by the meal type (Pmeal = 0.28) nor the blood collection method (Pmethod = 0.72). Similar results were observed with serum hsCRP concentrations (Ptime = 0.98, Pmeal = 0.25, Pmethod = 0.70).
4. Discussion The aim of this study was to evaluate the effect of an indwelling catheter on serum concentrations of IL-6, IL-8 and hsCRP in a fasting state and after a pro-inflammatory high-fat meal. Our hypotheses were that the catheter would significantly increase serum concentrations of inflammatory mediators, and that this inflammatory response would be local rather than systemic. As reported in other studies [8–11], our analyses showed that IL-6 concentrations increased significantly over time in serum collected through an IV catheter, but remained unchanged in serum collected by repeated venous punctures in the contralateral arm. These results suggest (1) a causative role of the catheter 3
Cytokine xxx (xxxx) xxx–xxx
K. Chabot et al.
Fig. 2. Time course of interleukin-8 (IL-8) concentrations in serum collected by venous punctures and through an indwelling catheter during a water-only (WO) test and after a high-fat meal (HFM). Data are presented as mean ± SEM.
provide continuous venous access and to avoid multiple venous punctures [7], it is known that a biofilm is formed when they are used for a prolonged time. Biofilms are a universal problem and are involved in various infections or diseases [20]. Biofilm provides habitats for microorganisms, in which they are protected from harmful conditions, such as antibacterial treatment, and these microorganisms can infect the host. In short-term catheterization, skin organisms that invade the percutaneous tract at the site of insertion are the major source of
endothelium, platelets contribute to the inflammatory response and tissue healing [2,17]. They release numerous mediators of inflammation, including cytokines. Platelets are a major source of IL-1beta [18] and animal studies suggested that they can contribute to the increase in IL-6 levels during injury [19]. Unfortunately, platelets were not measured in our study, therefore limiting the interpretation of our results. Although the use of an intravenous (IV) catheter is highly recommended in research facilities for physiology testing in order to
Fig. 3. Time course of high-sensitivity C-reactive protein (hsCRP) concentrations in serum collected by venous punctures and through an indwelling catheter during a water-only (WO) test and after a high-fat meal (HFM). Data are presented as mean ± SEM. 4
Cytokine xxx (xxxx) xxx–xxx
K. Chabot et al.
References
infection [21]. Biofilm composition depends on the surface characteristics of the device [22]. The only way to determine whether there is presence of a biofilm is to examine the device by scanning electron microscopy or by a culture, once removed from the body [22]. We did not assess the venous catheters used in our study for the presence of a biofilm; therefore we cannot exclude the possibility that biofilms have contributed to the inflammatory response observed in our study. We also hypothesized that a high-fat meal would have no additional effect on the local inflammation induced by the catheter. Numerous studies have investigated the effect of a high-fat meal on inflammation, but findings are inconsistent [12,23,24]. This could be explained, at least partly, by differences in study design variables, including meal size and composition, subject characteristics, previous acute exercise and method used to collect blood samples. A recent systemic review that characterized the magnitude and timing of the inflammatory response to a high-fat meal in healthy adults found that IL-6 consistently increase after a high-fat meal, with a peak 6 h postprandial [25]. Moreover, change in IL-6 levels was not associated with the BMI of the subjects. However, in line with other publications [26,27], and as hypothesized, there was no significant effect of the high-fat meal on IL-6 levels in our study (P = 0.27). Surprisingly, we found that baseline IL-6 concentrations were significantly higher before the high-fat meal than at the beginning of the water-only test. Yet, in both interventions, blood samples were collected through a catheter after an overnight fast. Therefore, neither the catheter, nor the meal could be responsible for this statistical difference. Furthermore, precautions were taken to conduce the interventions at the same phase of the menstrual cycle and to standardize lifestyle conditions in order to reduce confounding factors on inflammatory status. It is possible that the reported difference between groups is in fact due to a simple type I error, but factors such as psychological stress [28] or mild sleep deprivation [29] could contribute to this apparent intra-individual variation in fasting IL-6 concentrations. In the worst case scenario, this baseline difference in IL-6 concentrations would have tended to reject our hypothesis that a high-fat meal would have no additional effect on local inflammation.
[1] V. Kumar, A.K. Abbas, J.C. Aster, Inflammation and repair, in: Robbins Basic Pathology, Saunders (Ed.), Philadelphia, 2013, pp. 29–73. [2] R. Medzhitov, Origin and physiological roles of inflammation, Nature 454 (7203) (2008) 428–435. [3] K.E. Wellen, G.S. Hotamisligil, Inflammation, stress, and diabetes, J. Clin. Invest. 115 (5) (2005) 1111–1119. [4] X. Wang, W. Bao, J. Liu, Y.Y. Ouyang, D. Wang, S. Rong, et al., Inflammatory markers and risk of type 2 diabetes: a systematic review and meta-analysis, Diabetes Care 36 (1) (2013) 166–175. [5] G.R. Lichtenstein, S.B. Hanauer, W.J. Sandborn, Management of Crohn's disease in adults, Am. J. Gastroenterol. 104 (2) (2009) 465–483 quiz 4, 84. [6] V.P. Bykerk, P. Akhavan, G.S. Hazlewood, O. Schieir, A. Dooley, B. Haraoui, et al., Canadian Rheumatology Association recommendations for pharmacological management of rheumatoid arthritis with traditional and biologic disease-modifying antirheumatic drugs, J. Rheumatol. 39 (8) (2012) 1559–1582. [7] R. Maughan, S.M. Shirreffs, J.B. Leiper, Blood sampling, in: E.M. Winter (Ed.), Sport and Exercise Physiology Testing Guidelines: The British Association of Sport and Exercise Sciences guide, Routledge, New York, NY, 2007, p. 272. [8] A. Gudmundsson, W.B. Ershler, B. Goodman, S.J. Lent, S. Barczi, M. Carnes, Serum concentrations of interleukin-6 are increased when sampled through an indwelling venous catheter, Clin. Chem. 43 (11) (1997) 2199–2201. [9] M. Haack, A. Reichenberg, T. Kraus, A. Schuld, R. Yirmiya, T. Pollmacher, Effects of an intravenous catheter on the local production of cytokines and soluble cytokine receptors in healthy men, Cytokine 12 (6) (2000) 694–698. [10] W. Seiler, H. Muller, C. Hiemke, Interleukin-6 in plasma collected with an indwelling cannula reflects local, not systemic, concentrations, Clin. Chem. 40 (9) (1994) 1778–1779. [11] N.C. Dixon, T.L. Hurst, D.C. Talbot, R.M. Tyrrell, D. Thompson, Active middle-aged men have lower fasting inflammatory markers but the postprandial inflammatory response is minimal and unaffected by physical activity status, J. Appl. Physiol. 107 (1) (2009) 63–68 (1985). [12] M. Herieka, C. Erridge, High-fat meal induced postprandial inflammation, Mol. Nutr. Food Res. 58 (1) (2014) 136–146. [13] M.B. Pepys, G.M. Hirschfield, C-reactive protein: a critical update, J. Clin. Invest. 111 (12) (2003) 1805–1812. [14] C. Mitaka, Clinical laboratory differentiation of infectious versus non-infectious systemic inflammatory response syndrome, Clin. Chim. Acta 351 (1–2) (2005) 17–29. [15] P. Hillyer, E. Mordelet, G. Flynn, D. Male, Chemokines, chemokine receptors and adhesion molecules on different human endothelia: discriminating the tissue-specific functions that affect leucocyte migration, Clin. Exp. Immunol. 134 (3) (2003) 431–441. [16] D. Weiss, S. Avraham, R. Guttlieb, L. Gasner, A. Lotman, O.M. Rotman, et al., Mechanical compression effects on the secretion of vWF and IL-8 by cultured human vein endothelium, PLoS One 12 (1) (2017) e0169752. [17] S.J. Kim, R.P. Davis, C.N. Jenne, Platelets as modulators of Inflammation, Semin. Thromb. Hemost. 44 (2) (2018) 91–101. [18] S. Lindemann, N.D. Tolley, D.A. Dixon, T.M. McIntyre, S.M. Prescott, G.A. Zimmerman, et al., Activated platelets mediate inflammatory signaling by regulated interleukin 1beta synthesis, J. Cell Biol. 154 (3) (2001) 485–490. [19] N. Ding, G. Chen, R. Hoffman, P.A. Loughran, C.P. Sodhi, D.J. Hackam, et al., Tolllike receptor 4 regulates platelet function and contributes to coagulation abnormality and organ injury in hemorrhagic shock and resuscitation, Circ. Cardiovasc. Genet. 7 (5) (2014) 615–624. [20] M.S. Aparna, S. Yadav, Biofilms: microbes and disease, Braz. J. Infect. Dis. 12 (6) (2008) 526–530. [21] S.S. Talsma, Biofilms on medical devices, Home Healthc. Nurse 25 (9) (2007) 589–594. [22] M. Habash, G. Reid, Microbial biofilms: their development and significance for medical device-related infections, J. Clin. Pharmacol. 39 (9) (1999) 887–898. [23] F. Schwander, K.A. Kopf-Bolanz, C. Buri, R. Portmann, L. Egger, M. Chollet, et al., A dose-response strategy reveals differences between normal-weight and obese men in their metabolic and inflammatory responses to a high-fat meal, J. Nutr. 144 (10) (2014) 1517–1523. [24] A. Schmid, N. Petry, B. Walther, U. Butikofer, W. Luginbuhl, D. Gille, et al., Inflammatory and metabolic responses to high-fat meals with and without dairy products in men, Br. J. Nutr. 113 (12) (2015) 1853–1861. [25] S.R. Emerson, S.P. Kurti, C.A. Harms, M.D. Haub, T. Melgarejo, C. Logan, et al., Magnitude and timing of the postprandial inflammatory response to a high-fat meal in healthy adults: a systematic review, Adv. Nutr. 8 (2) (2017) 213–225. [26] D. Esser, E. Oosterink, J. Op't Roodt, R.M. Henry, C.D. Stehouwer, M. Müller, et al., Vascular and inflammatory high fat meal responses in young healthy men; a discriminative role of IL-8 observed in a randomized trial, PLoS One 8 (2) (2013) e53474. [27] L.K. Phillips, J.M. Peake, X. Zhang, I.J. Hickman, D.R. Briskey, B.E. Huang, et al., Postprandial total and HMW adiponectin following a high-fat meal in lean, obese and diabetic men, Eur. J. Clin. Nutr. 67 (4) (2013) 377–384. [28] A. Steptoe, M. Hamer, Y. Chida, The effects of acute psychological stress on circulating inflammatory factors in humans: a review and meta-analysis, Brain Behav. Immun. 21 (7) (2007) 901–912. [29] A.N. Vgontzas, E. Zoumakis, E.O. Bixler, H.M. Lin, H. Follett, A. Kales, et al., Adverse effects of modest sleep restriction on sleepiness, performance, and inflammatory cytokines, J. Clin. Endocrinol. Metab. 89 (5) (2004) 2119–2126.
5. Conclusion In conclusion, our study provides a template for collection of basal data on healthy individuals. Our main findings are that the insertion of an indwelling catheter is associated with a local inflammatory response mediated by IL-6 but not IL-8 and that this inflammatory response was not modulated by the pro-inflammatory high-fat meal. Although blood collection through an IV catheter is more convenient for both research participants and staff, the use of such a catheter could impact on the assessment of inflammation during physiology testing and bias the interpretation of the data. This blood sampling method should therefore be discussed as a potential limitation in future publications, especially when IL-6 concentrations are reported. Acknowledgments This work was supported by grants from the J-A DeSève Chair for Clinical Research to R.R.-L. R.R.-L holds a senior scholar from Fonds de recherche du Québec – Santé. Author contributions: K.C. acquired, analyzed, and interpreted the data; wrote the manuscript; and approved the final version to be published. M.-E.L. acquired, analyzed, and interpreted the data; and approved the final version to be published. J-P.B. edited and revised the manuscript, and approved the final version to be published. R.R.-L. designed the research, obtained funding, edited and revised the manuscript, and approved the final version to be published. Disclosure Statement. The authors have nothing to disclose. 5
Contents lists available at ScienceDirect
Cytokine journal homepage: www.elsevier.com/locate/cytokine
Intravenous catheters induce a local inflammatory response Katherine Chabotb, Marie-Eve Lavoiea,b, Jean-Philippe Bastardc,d,e, Rémi Rabasa-Lhoreta,b,
⁎
a
Department of Nutrition, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada Institut de recherches cliniques de Montréal (affiliated to the Université de Montréal), 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada AP-HP, Hôpital Tenon, UF Bio-marqueurs Inflammatoires et Métaboliques, Service de Biochimie et Hormonologie, Paris F75020, France d Sorbonne Universities UPMC Paris 6, UMR_S 938 CDR-Saint-Antoine, F-75012 Paris, France e University Hospital ICAN Institute, Paris, France b c
A R T I C LE I N FO
A B S T R A C T
Keywords: Inflammation IL-6 CRP Intravenous catheter
Aim: Chronic inflammation has been associated to the development of cardiometabolic dysfunctions. The use of an intravenous (IV) catheter is highly recommended for physiology testing. Yet, the presence of an IV catheter triggers local inflammation that does not reflect systemic inflammatory status. The aim of this study was to assess the effect of an IV catheter on serum concentrations of IL-6, IL-8 and hsCRP in a fasting state and after a high-fat meal known to trigger low-grade inflammation. Methods: Twenty-two healthy subjects (7 men, 15 women) were included in this study. The trial included 2 visits. After an overnight fast, a venous catheter was inserted into an antecubital vein. A first blood sample was collected through this catheter at T = 0 min. On each visit, participants were requested either to drink only water for the whole duration of the test (WO test), or to consume a high-fat meal (HFM). Blood samples were collected through the catheter at T60, T120, T180 and T300 min. Additional venous punctures were performed on the contralateral arm at T180 and T300 min. Serum inflammatory mediators were measured at each time point of both interventions. Results: When serum was collected by venous punctures, IL-6 concentrations remained unchanged during both WO and HFM tests (Ptime = 0.15 and Ptime = 0.23, respectively), whereas the concentrations increased progressively over time when serum was collected through the catheter (Ptime < 0.001). The high-fat meal had no additional effect on IL-6 levels (Pmeal = 0.27) neither in serum collected by venous puncture nor in serum collected through the catheter. Serum IL-8 and hsCRP concentrations did not vary over time, and were influenced neither by the meal type nor by the blood collection method. Conclusion: The insertion of an indwelling catheter is associated with a local inflammatory response possibly mediated by IL-6 but not IL-8. This inflammatory response was not enhanced by a pro-inflammatory high-fat meal.
1. Introduction
Chronic low-grade inflammation has been associated to the development of cardiometabolic dysfunctions such as insulin resistance, type 2 diabetes and atherosclerosis [3]. Elevated blood concentrations of inflammatory molecules and biomarkers (e.g. interleukin [IL]-6, C-reactive protein [CRP]) predict future development of insulin resistance and type 2 diabetes [4]. On the other hand, cytokines are regularly used to monitor the activity of inflammatory conditions such as arthritis and Crohn’s disease and to assess effectiveness of their treatment [5,6]. In research facilities, the use of an intravenous (IV) catheter is highly recommended for physiology testing in order to provide continuous venous access and to avoid multiple venous punctures [7]. Yet, it has been suggested that the presence of an IV catheter triggers a local
Inflammation is a protective host response intended to eliminate the cause of cell injury and to restore homeostasis [1]. It is induced by exogenous (e.g. microbes, allergens, foreign bodies) and/or endogenous stimuli (e.g. damaged vascular endothelium, monosodium urate crystals, auto anti-bodies), and is mediated by inflammatory molecules such as vasoactive amines, arachidonic acid metabolites, cytokines and chemokines [1,2]. The inflammatory response can be subdivided into acute or chronic: while acute inflammation has a rapid onset and a short duration, chronic inflammation has a more insidious development [1].
Abbreviations: BMI, body mass index; CRP, C-reactive protein; HFM, high fat meal; IL, interleukin; IV, intravenous; LBM, lean body mass; TNF, tumor necrosis factor; WO, water only ⁎ Corresponding author at: Institut de recherches cliniques de Montréal (IRCM), 110, avenue Des Pins Ouest, Montréal, Québec H2W 1R7, Canada. E-mail address: [email protected] (R. Rabasa-Lhoret). https://doi.org/10.1016/j.cyto.2018.05.034 Received 4 November 2017; Received in revised form 13 April 2018; Accepted 29 May 2018 1043-4666/ © 2018 Elsevier Ltd. All rights reserved.
Please cite this article as: Chabot, K., Cytokine (2018), https://doi.org/10.1016/j.cyto.2018.05.034
Cytokine xxx (xxxx) xxx–xxx
K. Chabot et al.
test). Subsequent blood samples were collected through the catheter at T60, T120, T180 and T300 min. Additional venous punctures were performed on the contralateral arm at T180 and T300 min. Subjects who were randomized to the water-only test on their first visit would be requested to consume the high-fat meal on their next visit, and vice versa. The two interventions were separated by 1 to 4 weeks. For women subjects specifically, the interventions were separated by exactly 1 month such that both test occurred at the same phase of their menstrual cycle (i.e. 10 days following the onset of menses). All subjects were asked to standardize their lifestyle for the 2 days preceding each test to minimize the confounding effect of variations in diet and/or exercise habits on inflammation.
inflammatory reaction at the insertion site, and that this local inflammation detectable in blood samples does not reflect systemic inflammatory status [8–11]. To date, studies have mainly focused on the effect of the catheter on IL-6 concentrations, except for Haack et al. who also evaluated plasma concentrations of tumor necrosis factor α (TNFα), but showed no significant effect of the catheter on this cytokine [9]. Nevertheless, these few studies suggest that blood collection through an indwelling catheter could introduce a significant bias in the assessment of inflammation. The aim of this study is thus to assess the effect of an IV catheter on serum concentrations of IL-6, IL-8 and hsCRP in a fasting state and after a high-fat meal known to trigger low-grade systemic inflammation [12]. We hypothesize that the catheter will increase serum concentrations of inflammatory mediators locally, but not systemically, and that a highfat meal will have no additional effect on this local inflammatory response.
2.4. High-fat test meal The high-fat meal consisted of 50 g of cheddar cheese, one slice (30 g) of bread and a milkshake made with 250 mL of 3.25% fat milk, 250 mL of vanilla ice cream, 100 mL of eggs and 15 mL of cocoa powder. This meal provided 867 kcal and its macronutrients composition was as follows: 17% of total energy intake from proteins, 31% from carbohydrates and 52% from lipids.
2. Subjects and methods 2.1. Subjects Twenty-two healthy subjects (7 men, 15 women), all students or staff of the Institut de Recherches Cliniques de Montreal (IRCM), were included in this study. Subjects were included if they met the following criteria: age 18–50 years; body mass index (BMI) 18–27 kg/m2; nonsmoking; stable weight ( ± 3 kg) for 3 months; good venous access. The exclusion criteria were as follows: (1) type 1 or type 2 diabetes; (2) hypertension; (3) dyslipidemia; (4) acute medical event in the previous 4 months; (5) symptomatic infectious event in the previous month; (6) history of chronic inflammatory disease or cancer; (7) use of drugs that may modulate inflammation (unless dose was stable for ≥ 1 month); (8) any unstable chronic condition (e.g. untreated hypothyroidism); (9) lactose intolerance, or intolerance to any food included in the test meal; (10) pregnant or breastfeeding women. This randomized, crossover intervention study was approved by the IRCM’s ethics committee. Subjects were recruited and examined by our research team from 2010 to 2013. All enrolled subjects read and signed a consent form prior to the beginning of proceedings.
2.5. Blood analysis Serum inflammatory mediators IL-6 and IL-8 were measured at each time point of both interventions using commercially available ELISA kits (Quantikine, Minneapolis, MN, USA). Serum high-sensitive CRP (hsCRP) was measured by an automated analyzer (COBAS INTEGRA® 400, Roche Diagnostic, Montreal, Canada) at T0, T180 and T300 min of each intervention. 2.6. Statistical analysis The D’Agostino and Pearson omnibus normality test was used to evaluate the distribution of all parameters. Skewed variables were analyzed using nonparametric tests. We performed three-way ANOVAs using time (Ptime), meal type (Pmeal) and blood collection method (Pmethod) as independent variables and serum IL-6, IL-8 or hsCRP as dependent variables. In case of significant interaction, an additional Wilcoxon rank test or a Friedman test was performed, as appropriate. Dunn's multiple comparison tests were used in case of a significant Pvalue, when appropriate. All statistical analyses were performed using SPSS Statistics Version 24.0 for Windows (SPSS Inc., Chicago, IL, USA), and results were considered statistically significant when P < 0.05.
2.2. Preliminary characterization On their first visit, which took place 1 to 4 weeks before the main trial, all participants underwent a medical examination to determine their eligibility. Blood pressure and anthropometric parameters were also measured. Blood pressure was determined as the average of three readings in the left arm after subjects rested for 10 min using a Spot Vital Signs® Device (Welch Allyn Inc., San Diego, CA). Body weight and standing height were measured using a calibrated electronic scale (Balances Industrielles Montreal Inc., Montreal, Canada) and a wall stadiometer (Perspective Enterprises, Portage, MI, USA), respectively. Body mass index (BMI) was calculated as follows: BMI (kg/m2) = [body weight/height2]. Waist circumference was measured with a non-extendable linear tape measure at the top of the iliac crest. Lean body mass (kg), fat mass (kg), and body fat percentage were measured by dual energy X-ray absorptiometry using a Lunar iDXA Podigy system (General Electric Lunar Corporation, Madison, WI, USA).
3. Results Anthropometric and hemodynamic characteristics of the study subjects are presented in Table 1. Fig. 1 depicts the 5-hour time course of IL-6 concentrations in serum collected by venous punctures and Table 1 Baseline anthropometric and hemodynamic characteristics of study subjects. Variables n Sex, F:M Age, y BMI, kg/m2 Waist circumference, cm Fat mass, kg LBM, kg Body fat, % Systolic blood pressure, mm Hg Diastolic blood pressure, mm Hg
2.3. Study design The main trial included two visits at our research facility. After a 12hour overnight fast, a venous catheter made of fluorinated ethylene propylene (Smiths Medical Jelco®, 20G x 1¼ inch) was inserted into an antecubital vein. A first blood sample was collected through the catheter in Vacutainer® tubes at T = 0 min (T0). Participants were then requested either to drink only water for the whole duration of the test, or to consume a high-fat meal within 20 min (water allowed during the
27.4 23.3 80.8 16.9 45.8 26.1 108.2 69.7
22 15:7 ± ± ± ± ± ± ± ±
5.4 3.1 9.2 5.9 10.0 8.5 10.0 7.1
Data are expressed as mean ± SD. Abbreviations: F, female; M, male; BMI, body mass index; LBM, lean body mass. 2
Cytokine xxx (xxxx) xxx–xxx
K. Chabot et al.
Fig. 1. Time course of interleukin-6 (IL-6) concentrations in serum collected by venous punctures and through an indwelling catheter during a water-only (WO) test and after a high-fat meal (HFM). Data are presented as mean ± SEM. test. * p < 0.05; ** p < 0.01; *** p < 0. 001.
on inflammation, and (2) that this inflammatory response is localized rather than systemic. As expected, serum CRP concentrations were unchanged in our study. Indeed, CRP is produced almost exclusively by hepatocytes, mainly under transcriptional control in response to IL-6, IL-1 and TNFalpha. Its synthesis begins 4–6 h after stimulation and its maximum serum concentrations are reached usually in about 48 h [13,14]. In our study, serum IL-6 concentrations were increased locally, but not at the systemic level which could explain a lack of stimulation of hepatocytes to produce CRP. Interleukin 8 remained also unchanged during the test. However, unlike CRP, many different cell types, including dermal fibroblasts, keratinocytes, endothelial cells and platelets [15], have the ability to express and secrete IL-8. This chemokine is produced upon inflammation, infection and trauma, for example. Some evidences indicate that a catheter indwelling within a vein exerts constant pressure upon the endothelium, which can promote an inflammatory response. Recently, Weiss et al. showed that mechanical compression of in-vitro cultured endothelial cells increases the release of IL-8 by these cells [16]. However, we did not observe any effect of the indwelling catheter on the IL-8 levels. Similarly, the alteration of the cutaneous barrier following the insertion of a catheter did not seem to induce the secretion of IL-8 in our study. Interleukin-1 and TNF-alpha are considered the most important stimuli to induce IL-8 secretion [14], and the peak increase in IL-8 concentrations is observed 2 h after stimulation [15]. Unfortunately, serum concentrations of IL-1 and TNF-alpha have not been measured in this study, therefore limiting our interpretation of the results. Nevertheless, a previous study did not demonstrate a local increase in secretion of post-catheter TNF-alpha [9]. Moreover, the fact that IL-8 did not increase during the test is not in favor of a local increase in either TNF-alpha or IL-1. There is growing body of literature on the role played by platelets in inflammation. Platelets patrol the blood vasculature for endothelial damages and the presence of intravascular pathogens. Through their interactions with other cell types, including monocytes, neutrophils and
through an indwelling catheter, during a water-only (WO) test and after a high-fat meal (HFM). Mean concentrations of IL-6 were significantly higher in serum collected before the HFM as compared to serum collected at the beginning of the WO test (0.65 ± 0.92 pg/mL vs 0.30 ± 0.34 pg/mL, respectively, P = 0.02). At that time point, all samples were collected through an indwelling catheter. There was a significant interaction between time and blood collection method (P = 0.015). IL-6 concentrations remained unchanged during both WO and HFM tests (Ptime = 0.15 and Ptime = 0.23, respectively) when serum was collected by venous punctures, whereas the concentrations increased progressively over time to reach levels as high as 8-times the baseline concentrations when serum was collected through the catheter (Ptime < 0.001). Except for the significant difference in baseline IL-6 concentrations, the high-fat meal had no significant effect on IL-6 levels (Pmeal = 0.27) neither in serum collected by venous puncture nor in serum collected through an indwelling catheter. Figs. 2 and 3 show the time courses of IL-8 and hsCRP concentrations, respectively. Serum IL-8 concentrations did not vary over time (Ptime = 0.77), and were influenced neither by the meal type (Pmeal = 0.28) nor the blood collection method (Pmethod = 0.72). Similar results were observed with serum hsCRP concentrations (Ptime = 0.98, Pmeal = 0.25, Pmethod = 0.70).
4. Discussion The aim of this study was to evaluate the effect of an indwelling catheter on serum concentrations of IL-6, IL-8 and hsCRP in a fasting state and after a pro-inflammatory high-fat meal. Our hypotheses were that the catheter would significantly increase serum concentrations of inflammatory mediators, and that this inflammatory response would be local rather than systemic. As reported in other studies [8–11], our analyses showed that IL-6 concentrations increased significantly over time in serum collected through an IV catheter, but remained unchanged in serum collected by repeated venous punctures in the contralateral arm. These results suggest (1) a causative role of the catheter 3
Cytokine xxx (xxxx) xxx–xxx
K. Chabot et al.
Fig. 2. Time course of interleukin-8 (IL-8) concentrations in serum collected by venous punctures and through an indwelling catheter during a water-only (WO) test and after a high-fat meal (HFM). Data are presented as mean ± SEM.
provide continuous venous access and to avoid multiple venous punctures [7], it is known that a biofilm is formed when they are used for a prolonged time. Biofilms are a universal problem and are involved in various infections or diseases [20]. Biofilm provides habitats for microorganisms, in which they are protected from harmful conditions, such as antibacterial treatment, and these microorganisms can infect the host. In short-term catheterization, skin organisms that invade the percutaneous tract at the site of insertion are the major source of
endothelium, platelets contribute to the inflammatory response and tissue healing [2,17]. They release numerous mediators of inflammation, including cytokines. Platelets are a major source of IL-1beta [18] and animal studies suggested that they can contribute to the increase in IL-6 levels during injury [19]. Unfortunately, platelets were not measured in our study, therefore limiting the interpretation of our results. Although the use of an intravenous (IV) catheter is highly recommended in research facilities for physiology testing in order to
Fig. 3. Time course of high-sensitivity C-reactive protein (hsCRP) concentrations in serum collected by venous punctures and through an indwelling catheter during a water-only (WO) test and after a high-fat meal (HFM). Data are presented as mean ± SEM. 4
Cytokine xxx (xxxx) xxx–xxx
K. Chabot et al.
References
infection [21]. Biofilm composition depends on the surface characteristics of the device [22]. The only way to determine whether there is presence of a biofilm is to examine the device by scanning electron microscopy or by a culture, once removed from the body [22]. We did not assess the venous catheters used in our study for the presence of a biofilm; therefore we cannot exclude the possibility that biofilms have contributed to the inflammatory response observed in our study. We also hypothesized that a high-fat meal would have no additional effect on the local inflammation induced by the catheter. Numerous studies have investigated the effect of a high-fat meal on inflammation, but findings are inconsistent [12,23,24]. This could be explained, at least partly, by differences in study design variables, including meal size and composition, subject characteristics, previous acute exercise and method used to collect blood samples. A recent systemic review that characterized the magnitude and timing of the inflammatory response to a high-fat meal in healthy adults found that IL-6 consistently increase after a high-fat meal, with a peak 6 h postprandial [25]. Moreover, change in IL-6 levels was not associated with the BMI of the subjects. However, in line with other publications [26,27], and as hypothesized, there was no significant effect of the high-fat meal on IL-6 levels in our study (P = 0.27). Surprisingly, we found that baseline IL-6 concentrations were significantly higher before the high-fat meal than at the beginning of the water-only test. Yet, in both interventions, blood samples were collected through a catheter after an overnight fast. Therefore, neither the catheter, nor the meal could be responsible for this statistical difference. Furthermore, precautions were taken to conduce the interventions at the same phase of the menstrual cycle and to standardize lifestyle conditions in order to reduce confounding factors on inflammatory status. It is possible that the reported difference between groups is in fact due to a simple type I error, but factors such as psychological stress [28] or mild sleep deprivation [29] could contribute to this apparent intra-individual variation in fasting IL-6 concentrations. In the worst case scenario, this baseline difference in IL-6 concentrations would have tended to reject our hypothesis that a high-fat meal would have no additional effect on local inflammation.
[1] V. Kumar, A.K. Abbas, J.C. Aster, Inflammation and repair, in: Robbins Basic Pathology, Saunders (Ed.), Philadelphia, 2013, pp. 29–73. [2] R. Medzhitov, Origin and physiological roles of inflammation, Nature 454 (7203) (2008) 428–435. [3] K.E. Wellen, G.S. Hotamisligil, Inflammation, stress, and diabetes, J. Clin. Invest. 115 (5) (2005) 1111–1119. [4] X. Wang, W. Bao, J. Liu, Y.Y. Ouyang, D. Wang, S. Rong, et al., Inflammatory markers and risk of type 2 diabetes: a systematic review and meta-analysis, Diabetes Care 36 (1) (2013) 166–175. [5] G.R. Lichtenstein, S.B. Hanauer, W.J. Sandborn, Management of Crohn's disease in adults, Am. J. Gastroenterol. 104 (2) (2009) 465–483 quiz 4, 84. [6] V.P. Bykerk, P. Akhavan, G.S. Hazlewood, O. Schieir, A. Dooley, B. Haraoui, et al., Canadian Rheumatology Association recommendations for pharmacological management of rheumatoid arthritis with traditional and biologic disease-modifying antirheumatic drugs, J. Rheumatol. 39 (8) (2012) 1559–1582. [7] R. Maughan, S.M. Shirreffs, J.B. Leiper, Blood sampling, in: E.M. Winter (Ed.), Sport and Exercise Physiology Testing Guidelines: The British Association of Sport and Exercise Sciences guide, Routledge, New York, NY, 2007, p. 272. [8] A. Gudmundsson, W.B. Ershler, B. Goodman, S.J. Lent, S. Barczi, M. Carnes, Serum concentrations of interleukin-6 are increased when sampled through an indwelling venous catheter, Clin. Chem. 43 (11) (1997) 2199–2201. [9] M. Haack, A. Reichenberg, T. Kraus, A. Schuld, R. Yirmiya, T. Pollmacher, Effects of an intravenous catheter on the local production of cytokines and soluble cytokine receptors in healthy men, Cytokine 12 (6) (2000) 694–698. [10] W. Seiler, H. Muller, C. Hiemke, Interleukin-6 in plasma collected with an indwelling cannula reflects local, not systemic, concentrations, Clin. Chem. 40 (9) (1994) 1778–1779. [11] N.C. Dixon, T.L. Hurst, D.C. Talbot, R.M. Tyrrell, D. Thompson, Active middle-aged men have lower fasting inflammatory markers but the postprandial inflammatory response is minimal and unaffected by physical activity status, J. Appl. Physiol. 107 (1) (2009) 63–68 (1985). [12] M. Herieka, C. Erridge, High-fat meal induced postprandial inflammation, Mol. Nutr. Food Res. 58 (1) (2014) 136–146. [13] M.B. Pepys, G.M. Hirschfield, C-reactive protein: a critical update, J. Clin. Invest. 111 (12) (2003) 1805–1812. [14] C. Mitaka, Clinical laboratory differentiation of infectious versus non-infectious systemic inflammatory response syndrome, Clin. Chim. Acta 351 (1–2) (2005) 17–29. [15] P. Hillyer, E. Mordelet, G. Flynn, D. Male, Chemokines, chemokine receptors and adhesion molecules on different human endothelia: discriminating the tissue-specific functions that affect leucocyte migration, Clin. Exp. Immunol. 134 (3) (2003) 431–441. [16] D. Weiss, S. Avraham, R. Guttlieb, L. Gasner, A. Lotman, O.M. Rotman, et al., Mechanical compression effects on the secretion of vWF and IL-8 by cultured human vein endothelium, PLoS One 12 (1) (2017) e0169752. [17] S.J. Kim, R.P. Davis, C.N. Jenne, Platelets as modulators of Inflammation, Semin. Thromb. Hemost. 44 (2) (2018) 91–101. [18] S. Lindemann, N.D. Tolley, D.A. Dixon, T.M. McIntyre, S.M. Prescott, G.A. Zimmerman, et al., Activated platelets mediate inflammatory signaling by regulated interleukin 1beta synthesis, J. Cell Biol. 154 (3) (2001) 485–490. [19] N. Ding, G. Chen, R. Hoffman, P.A. Loughran, C.P. Sodhi, D.J. Hackam, et al., Tolllike receptor 4 regulates platelet function and contributes to coagulation abnormality and organ injury in hemorrhagic shock and resuscitation, Circ. Cardiovasc. Genet. 7 (5) (2014) 615–624. [20] M.S. Aparna, S. Yadav, Biofilms: microbes and disease, Braz. J. Infect. Dis. 12 (6) (2008) 526–530. [21] S.S. Talsma, Biofilms on medical devices, Home Healthc. Nurse 25 (9) (2007) 589–594. [22] M. Habash, G. Reid, Microbial biofilms: their development and significance for medical device-related infections, J. Clin. Pharmacol. 39 (9) (1999) 887–898. [23] F. Schwander, K.A. Kopf-Bolanz, C. Buri, R. Portmann, L. Egger, M. Chollet, et al., A dose-response strategy reveals differences between normal-weight and obese men in their metabolic and inflammatory responses to a high-fat meal, J. Nutr. 144 (10) (2014) 1517–1523. [24] A. Schmid, N. Petry, B. Walther, U. Butikofer, W. Luginbuhl, D. Gille, et al., Inflammatory and metabolic responses to high-fat meals with and without dairy products in men, Br. J. Nutr. 113 (12) (2015) 1853–1861. [25] S.R. Emerson, S.P. Kurti, C.A. Harms, M.D. Haub, T. Melgarejo, C. Logan, et al., Magnitude and timing of the postprandial inflammatory response to a high-fat meal in healthy adults: a systematic review, Adv. Nutr. 8 (2) (2017) 213–225. [26] D. Esser, E. Oosterink, J. Op't Roodt, R.M. Henry, C.D. Stehouwer, M. Müller, et al., Vascular and inflammatory high fat meal responses in young healthy men; a discriminative role of IL-8 observed in a randomized trial, PLoS One 8 (2) (2013) e53474. [27] L.K. Phillips, J.M. Peake, X. Zhang, I.J. Hickman, D.R. Briskey, B.E. Huang, et al., Postprandial total and HMW adiponectin following a high-fat meal in lean, obese and diabetic men, Eur. J. Clin. Nutr. 67 (4) (2013) 377–384. [28] A. Steptoe, M. Hamer, Y. Chida, The effects of acute psychological stress on circulating inflammatory factors in humans: a review and meta-analysis, Brain Behav. Immun. 21 (7) (2007) 901–912. [29] A.N. Vgontzas, E. Zoumakis, E.O. Bixler, H.M. Lin, H. Follett, A. Kales, et al., Adverse effects of modest sleep restriction on sleepiness, performance, and inflammatory cytokines, J. Clin. Endocrinol. Metab. 89 (5) (2004) 2119–2126.
5. Conclusion In conclusion, our study provides a template for collection of basal data on healthy individuals. Our main findings are that the insertion of an indwelling catheter is associated with a local inflammatory response mediated by IL-6 but not IL-8 and that this inflammatory response was not modulated by the pro-inflammatory high-fat meal. Although blood collection through an IV catheter is more convenient for both research participants and staff, the use of such a catheter could impact on the assessment of inflammation during physiology testing and bias the interpretation of the data. This blood sampling method should therefore be discussed as a potential limitation in future publications, especially when IL-6 concentrations are reported. Acknowledgments This work was supported by grants from the J-A DeSève Chair for Clinical Research to R.R.-L. R.R.-L holds a senior scholar from Fonds de recherche du Québec – Santé. Author contributions: K.C. acquired, analyzed, and interpreted the data; wrote the manuscript; and approved the final version to be published. M.-E.L. acquired, analyzed, and interpreted the data; and approved the final version to be published. J-P.B. edited and revised the manuscript, and approved the final version to be published. R.R.-L. designed the research, obtained funding, edited and revised the manuscript, and approved the final version to be published. Disclosure Statement. The authors have nothing to disclose. 5