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Effects of insulin therapy on inflammatory mediators in infants undergoing cardiac surgery with cardiopulmonary bypass
Cytokine 44 (2008) 96–100
Contents lists available at ScienceDirect
Cytokine journal homepage: www.elsevier.com/locate/issn/10434666
Effects of insulin therapy on inflammatory mediators in infants undergoing cardiac surgery with cardiopulmonary bypass Gu Chun-Hu a,1, Cui Qin a,1, Wang Yun-Ya b,1, Wang Jing b, Dou Ya-Wei a, Zhao Rong a, Liu Yang a, Wang Jin a, Pei Jian-Ming c,*, Yi Ding-Hua a,* a
Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, 15# Changle West Road, Xi’an 710032, Shaanxi, China Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, Shaanxi, China c Department of Physiology, National Key Discipline of Cell Biology, Fourth Military Medical University, 169# Changle West Road, Xi’an 710032, Shaanxi, China b
a r t i c l e
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Article history: Received 15 February 2008 Received in revised form 4 June 2008 Accepted 27 June 2008
Keywords: Insulin Cardiopulmonary bypass Interleukin Tumor necrosis factor Nuclear factor-jBp65 IjB
a b s t r a c t To determine whether insulin administration modulates the systemic inflammatory response in infants undergoing cardiac surgery with cardiopulmonary bypass, 60 infants undergoing cardiopulmonary bypass were randomly assigned into a routine therapy group or to an intensive insulin therapy group with 30 infants in each group. Plasma IL-1b, IL-6, IL-10, and TNF-a levels were determined before anesthesia, at the initiation of cardiopulmonary bypass, and at 0, 6, 12, 24, and 48 h after cardiopulmonary bypass. Nuclear factor-jBp65 expression and IjB expression in peripheral blood mononuclear cells were also measured by Western blot analysis. TNF-a, IL-1b, IL-6, and IL-10 levels were all elevated after the initiation of cardiopulmonary bypass. However, TNF-a, IL-1b, and IL-6 levels were significantly attenuated in the intensive insulin therapy group compared to those in the routine therapy group after initiation of cardiopulmonary bypass (p < 0.05 or <0.01). Meanwhile, plasma IL-10 levels were significantly higher in the intensive insulin therapy group than in the routine therapy group after initiation of cardiopulmonary bypass (p < 0.05 or <0.01). Accordingly, Nuclear factor-jBp65 expression and IjB expression were significantly increased after initiation of cardiopulmonary bypass in both groups (p < 0.05 or <0.01). The expression of Nuclear factor-jBp65, which induces the transcription of pro-inflammatory cytokines was significantly attenuated in the intensive insulin therapy group (p < 0.05 or <0.01). Meanwhile, the expression of IjB, an inhibitor of NF-jB, was significantly higher in the intensive insulin therapy group (p < 0.05 or <0.01). These results suggested that intensive insulin therapy may attenuate the systemic inflammatory response in infants undergoing cardiopulmonary bypass. Ó 2008 Published by Elsevier Ltd.
1. Introduction Cardiac surgery with cardiopulmonary bypass (CPB) provokes a systemic inflammatory response. This inflammatory reaction and injury may contribute to the development of postoperative complications [1,2]. The magnitude and duration of the systemic inflammatory response determines the development and degree of tissue damage, multiorgan failure, or even death [3,4]. The pathophysiological cascade is mediated by pro-inflammatory cytokines, such as IL-1b, IL-6, or TNF, that are potentially detrimental. Pro-inflammatory mediators are balanced by antiinflammatory cytokines, such as IL-2, IL-4, or IL-10 [5]. It has been shown that the expression and synthesis of pro- and anti-inflammatory cytokines are controlled by signal transcription factors [6].
* Corresponding authors. Fax: +86 29 83210092 (D.-H. Yi). E-mail addresses: [email protected] (J.-M. Pei), [email protected] (D.-H. Yi). 1 These authors contributed equally to this work. 1043-4666/$ - see front matter Ó 2008 Published by Elsevier Ltd. doi:10.1016/j.cyto.2008.06.014
The prime cellular signal of inflammation is the transcription factor, Nuclear factor kappaB (NF-jB), which induces the transcription of pro-inflammatory cytokines, adhesion molecules, and enzymes generating reactive oxygen species (ROS), and IjB is an inhibitor of NF-jB [7]. Despite recent advances in the understanding of the molecular cascade of the systemic inflammatory response, the lack of an effective treatment still remains a clinical problem. Insulin given at doses to maintain blood glucose at less than 110 mg/dL has been reported to decrease the incidence of complications and reduce the fatality rate in critically ill patients who require intensive care for more than five days and improve the patients’ prognosis [8,9]. The mechanisms by which insulin improves survival in critically ill patients have not been elucidated so far. Insulin has been shown to alter inflammatory mediators and improve liver morphology and function after a thermal injury [10,11]. In recent observations, insulin has been shown to suppress several pro-inflammatory transcription factors, such as Nuclear factor (NF)-jB, Egr-1, and activating protein-1 (AP-1) and the corresponding genes regulated by
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them, which mediate inflammation [6,12]. However, there are few studies on the mechanism and effects of intensive insulin therapy on inflammatory cytokines in patients during CPB, especially in infants. Therefore, the aim of the present study was to determine whether insulin administration modulates the systemic inflammatory response in infants undergoing CPB.
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blood glucose of 2.8–3.3 mmol/L. When the blood glucose level was below 2.8 mmol/L, insulin infusion was discontinued, and 10 mL of 20% glucose was infused intravenously. (4) Insulin was discontinued when rewarming. (5) The postoperative blood glucose level was adjusted to ‘U/kg/h’ by the schedule of Ref. [13]. 2.3. Determination of insulin, IL-1b, IL-6, IL-10, and TNF-a
2. Methods 2.1. Patients The study was approved by our Local Ethics Committee. Anonymous data acquisition and data publication are in accordance with the Declaration of Helsinki. Preoperatively all the infants’ parents received detailed information on the insulin therapy and gave their written consent. Sixty infants undergoing cardiac surgery with CPB for congenital heart disease were enrolled at our hospital from August 2006 to January 2007. None of the infants had a history of diabetes mellitus. These infants were randomly divided into a routine therapy group (n = 30) and an intensive insulin therapy group (n = 30). The patient characteristics are summarized in Table 1. No significant difference was found in age, sex, body weight, or any other operative procedure between the two groups (Table 1). Exclusive criteria included: preoperative liver and kidney disease or dysfunction, preoperative coagulation disorder, palliative operation or second operation, or impairment of blood glucose control. 2.2. Blood glucose control Blood glucose levels were 4.4–10.0 mmol/L during the operation and 4.4–8.3 mmol/L after the operation in the intensive insulin therapy group. Changes in blood glucose levels were not controlled in the routine therapy group. Patients in the routine therapy group received standard institutional operative and postoperative care. For the intensive insulin therapy group, the intraoperative schedule was as follows. (1) Insulin was infused into the central vein of infants at 0.2 U/kg/h with a micro pump after anesthesia. (2) The flow rate was adjusted to 0.5 U/kg/h after the infants underwent thoracotomy. (3) The flow rate was adjusted to 1.5–2 U/kg/ h when IL was determined. Blood glucose was measured every 15 min. The insulin infusion was regulated as follows. The flow rate would be increased by 0.2 U/kg/h for 8.9–9.4 blood glucose of mmol/L; increased by 0.4 U/kg/h for blood glucose of 9.4– 10.0 mmol/L; increased by 0.6 U/kg/h for blood glucose over 10.0 mmol/L. The flow rate would be decreased by 0.2 U/kg/h for blood glucose of 3.3–3.9 mmol/L; decreased by 0.5 U/kg/h for
Table 1 Baseline characteristics and operative data of infants Data
IT group (n = 30)
RT group (n = 30)
Male gender (%) Age (year) Body weight (kg) Left ventricular ejection fraction (%) Cardiopulmonary bypass time (min) Cross-clamping time (min) Cardiopulmonary bypass -flow (L/min/m2) Ultrafiltration (mL/kg) Insulin (lU/mL) Blood glucose level (mmol/L) Tumor necrosis factor-a (pg/mL) Interleukin-1b (pg/mL) Interleukin-6 (pg/mL) Interleukin-10 (pg/mL)
18 (60) 1.4 ± 0.5 5.7 ± 2.0 66.0 ± 7.2 55.2 ± 3.9 31.6 ± 2.4 2.9 ± 0.3 342 ± 35 7.9 ± 1.6 4.5 ± 0.6 31.9 ± 2.5 6.3 ± 1.2 18.9 ± 3.7 50.9 ± 3.6
16 (53) 1.6 ± 0.4 6.2 ± 1.6 64.5 ± 5.1 58.1 ± 2.8 32.4 ± 3.8 3.0 ± 0.2 334 ± 32 8.3 ± 1.6 4.3 ± 0.8 32.3 ± 3.2 6.2 ± 1.5 21.2 ± 2.5 46.6 ± 4.6
Data are presented as the number (%) of patients or mean values ± SD. RT group, routine therapy group; IT group, intensive insulin therapy group.
Blood samples were taken in heparinized tubes at 7 time points for each patient as follows: before surgical anesthesia (T1), at the initiation of CPB (T2), at the termination of CPB (T3), 6 h after CPB (T4), 12 h after CPB (T5), 24 h after CPB (T6), and 48 h after CPB (T7). Plasma insulin levels were measured in all infants of the two groups with an Insulin Kit (R&D Systems, Abingdon, UK). Plasma IL-6, IL-8, IL-10, as well as TNF-a levels were determined using commercially available ELISA kits (R&D Systems, Abingdon, UK) as our previous study documented [14]. All enzyme-linked immunoabsorption assay (ELISA) protocols were carried out according to kit guidelines. Results of the measurements were corrected according to the following formula: Taking an example of the haematocrit, the corrected value is equal to the actual measure (1 haematocrit sample level)/(1 haematocrit level before anesthesia). 2.4. Peripheral blood mononuclear cell isolation from blood samples Blood samples were collected in Na–EDTA as an anticoagulant. Anticoagulant-treated blood was thoroughly mixed with Hanks’ solution (1:1) and layered on Ficoll-Paque solution and centrifuged at 800g for 15 min at 20 °C. First, the upper layer of plasma was discarded. Then the lymphocyte layer was transferred to a clean centrifuge tube containing 4–5 mL Hanks’ solution and centrifuged at 800g for 10 min. The upper layer was discarded. Two washing steps followed, adding three volumes of Hanks’ solution and centrifugation at 800g for 10 min at 20 °C. The supernatant was removed, and the peripheral blood mononuclear cells (PBMCs) in the pellets were reconstituted to a concentration of 4 105 cells/ mL in Hanks’ solution. 2.5. Western blot PBMC lysates were prepared by adding 1 mL boiling lysis buffer (1% SDS), 1 mm sodium ortho-vanadate, 10 mm Tris (pH 7.4) to the PBMC pellet. The protein concentration was quantitated with the BCA protein quantitation kit (Pierce, USA). Sixty micrograms of total cell lysate were electrophoresed on 12% SDS for NF-jBp65 or 15% SDS for IjB. Protein was isolated by SDS/PGEA electrophoresis, transferred onto polyvinylidene difluoride (Bio-Rad Laboratories, USA) by the semi-dry electrophoretic transfer technique, blocked with 5% skimmed milk, and incubated with polyclonal antibody against IkB (Sigma, USA) or a monoclonal antibody against NF-jBp65 (Sigma, USA) overnight at 4 °C, and then incubated with the corresponding second antibody at room temperature for 1 h after washing the membranes. An immunodetection kit was used for fluorescence detection (Pierce, USA). 2.6. Statistical analysis Measurements were presented as means ± SD. Statistical analysis was performed using SPSS 11.0 software. Standard methods were used, as indicated in the figure legends and tables—for example, repeated measures analysis of variance (ANOVA) models and ordinary ANOVA models (see Section 3) (Figs. 1–4), and t-tests (Table 1). A value of p < 0.05 was considered statistically significant.
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Fig. 1. Changes in blood glucose levels and insulin levels in the perioperative period. *p < 0.05, **p < 0.01 compared with basal levels. #p < 0.05, ##p < 0.01 compared with RT group. The error bars are the standard deviation (CPB, cardiopulmonary bypass; RT group, routine therapy group; IT group, intensive insulin therapy group; T, time; T1, before anesthesia; T2, initiation of CPB; T3, termination of CPB; T4, 6 h after CPB; T5, 12 h after CPB; T6, 24 h after CPB; T7, 48 h after CPB.).
Fig. 2. Pre and postoperative interleukins. *p < 0.05, **p < 0.01 compared with basal levels. #p < 0.05, ##p < 0.01 compared with RT group. The error bars are the standard deviation. IL-1b, IL-6, and TNF-a levels are higher than basal levels and did not normalize within the study period in the RT group (A–C). However, there was no significant difference in IL-10 levels between the RT group and IT group (IL, interleukins; TNF, tumor necrosis factor-a; CPB, cardiopulmonary bypass; RT group, routine therapy group; IT group, intensive insulin therapy group; T, time; T1, before anesthesia; T2, initiation of CPB; T3, termination of CPB; T4, 6 h after CPB; T5, 12 h after CPB; T6, 24 h after CPB; T7, 48 h after CPB.).
3. Results 3.1. Changes in blood glucose level and insulin levels After anesthesia, there was a biphasic response of blood glucose levels in the routine group (Fig. 1A). The first phase consisted of an
increase in blood glucose levels 1.7-fold at the initiation of CPB and 3.1-fold at the end of CPB, relative to the preoperative baseline level, respectively. The blood glucose level transiently decreased to 2.7-fold the baseline level 6 h after CPB. The second phase of the increase in blood glucose levels occurred 12 h after CPB, then continuously decreased, but did not reach the preoperative level
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therapy group than in the routine therapy group at each time point after CPB (p < 0.05 or 0.01). 3.2. Changes in plasma IL-1b, IL-6, TNF-a, and IL-10 levels
Fig. 3. Changes in NF-jBp65 expression in peripheral blood mononuclear cells. * p < 0.05, **p < 0.01 compared with basal levels. #p < 0.05, ##p < 0.01 compared with RT group. (A) Representative Western blot showing the increase in NF-jBp65 quantity in peripheral blood mononuclear cell homogenates following routine therapy (upper gel) or intensive insulin therapy (lower gel). (B) Densitometric quantitative analysis of NF-jBp65 protein content (CPB, cardiopulmonary bypass; RT group, routine therapy group; IT group, intensive insulin therapy group; NF-jBp65, Nuclear factor jBp65; T, time; T1, before anesthesia; T2, initiation of CPB; T3, termination of CPB; T4, 6 h after CPB; T5, 12 h after CPB; T6, 24 h after CPB; T7, 48 h after CPB.).
The pro-inflammatory cytokines TNF-a, IL-1b, and IL-6 showed a monophasic response in both groups (Fig. 2A–C). Samples from the routine therapy group showed a 2.7-fold increase for TNF-a, a 6.6-fold increase for IL-1b, and a 7.6-fold increase for IL-6 6 h after CPB, then a decrease, although not back to the preoperative level 48 h after CPB (Fig. 2A–C). Although the monophasic response of TNF-a, IL-1b, and IL-6 was similar in both groups, the levels remained significantly higher in the routine therapy group compared with the intensive insulin therapy group at each time point after the initiation of CPB (p < 0.05 or 0.01) (Fig. 2A–C). Anti-inflammatory cytokine IL-10 levels were elevated immediately after CPB, and reached a peak at 12 h after CPB, then decreased, but did not reach the preoperative level 48 h after CPB in either group. IL-10 levels were significantly higher in the insulin therapy group than in the routine therapy group at each time point after the termination of CPB (p < 0.05 or 0.01) (Fig. 2D). 3.3. Changes in NF-jBp65 and IjB expression in the PBMCs Fig. 3A shows a representative Western blot of NF-jBp65 expression in the two groups. NF-jBp65 in PBMCs were increased significantly after the termination of CPB in both groups, with a peak at 6 h after CPB (252 ± 52% of the basal level for the routine therapy group, 395 ± 102% of the basal level for the insulin therapy group), then they decreased, but did not reach the preoperative level 48 h after CPB in either group. NF-jBp65 expression was significantly lower in insulin therapy group than in the routine therapy group after the termination of CPB (p < 0.05 or 0.01) (Fig. 3B). Fig. 4A shows a representative Western blot of IjB expression in the two groups. IjB protein levels in PBMCs in the insulin therapy group increased significantly to 172 ± 30% at the end of CPB, peaked at 6 h after CPB (332 ± 100% of the basal level) and declined at 12 h after CPB, but did not reach the preoperative level 48 h after CPB. IjB expression was significantly higher in the insulin therapy group than in the routine therapy group at each time point after the termination of CPB (p < 0.05 or 0.01). (Fig. 4B). 3.4. Clinical results
Fig. 4. Changes in IjB expression in the peripheral blood mononuclear cells. * p < 0.05, **p < 0.01 compared with basal levels. #p < 0.05, ##p < 0.01 compared with RT group. (A) Representative Western blot showing the increase in IjB in peripheral blood mononuclear cell homogenates following routine therapy (upper gel) or intensive insulin therapy (lower gel). (B) Densitometric quantitative analysis of IjB protein content (CPB, cardiopulmonary bypass; RT group, routine therapy group; IT group, intensive insulin therapy group; T, time; T1, before anesthesia; T2, initiation of CPB; T3, termination of CPB; T4, 6 h after CPB; T5, 12 h after CPB; T6, 24 h after CPB; T7, 48 h after CPB.).
All the patients survived. The duration of postoperative mechanical ventilation was 7.2 ± 1.6 h in the control group and 10.3 ± 1.8 h in the intensive insulin therapy group (p < 0.05). The length of stay in the intensive care unit was 65.3 ± 12.1 h in the routine therapy group and 48.9 ± 12.9 h in the intensive insulin therapy group (p < 0.05).
at 48 h after CPB. Blood glucose levels were reasonably controlled in the intensive insulin therapy group. Blood glucose levels were significantly higher in the routine group than in the intensive insulin therapy group at each time point after initiation of CPB (p < 0.05 or 0.01) (Fig. 1A). An apparently similar biphasic response could be observed for plasma levels of insulin in both groups (Fig. 1B). After a first increase 0 h postoperatively (4.6-fold for the intensive therapy group and 2.6-fold for the routine therapy group), plasma insulin levels declined transiently in both groups after 6 h, but the second phase of increase after 12 h was not as marked as the first phase (Fig. 1B). Insulin levels were significantly higher in the intensive insulin
Many studies have verified that intensive insulin therapy could improve the prognosis of severe diseases, especially cardiovascular disease [7,8,15]. However, its mode of action has not been clearly identified so far. This study investigated the effects of intensive insulin therapy on pro-inflammatory cytokines, anti-inflammatory cytokines levels, and the expression of NF-jBp65 and IjB in the PBMCs in infants undergoing CPB. CPB provokes a systemic inflammatory response. This inflammatory reaction and injury may contribute to the development of postoperative complications. Our study showed that TNF-a, IL-1b, IL-6 levels, and NF-jB expression were significantly increased after the initiation of CPB in both groups. Several factors
4. Discussion
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may contribute to such problems. First, CPB could activate the complement system and produce anaphylatoxin that could activate neutrophils, macrophages, and monocytes. Second, CPB always causes stress hyperglycemia because of anesthesia, operation, postoperative pain, dysphoria of patients, use of assisted ventilation, and so on [16]. Hyperglycemia could promote oxidative stress and induce Nuclear factor-jB activation [17]. Additionally CPB could impair the barrier function of the digestive tract, allowing bacteria into the blood circulation, resulting in endotoxemia [16]. Endotoxins could generate TNF by activating macrophages and monocytes [16,18]. Furthermore, interaction of various cytokines occurs [19]. TNF-a, IL-1, and IL-6 generated in the early inflammatory reaction could trigger an inflammatory reaction and amplify the inflammatory process [14]. Activated TNF-a could reactivate NF-jB and cause the excessive activation of Nuclear factor jB. Peripheral blood mononuclear cells are cellular mediators of inflammation. The prime cellular signal of inflammation is the transcription factor, NF-jB, that leads to the transcription of proinflammatory cytokines and adhesion molecules and to enzymatic mechanisms that cause generation of reactive oxygen species (ROS) [20,21]. IjB binds to cytosolic NF-jB and prevents its translocation into the nucleus [22,23]. Our data showed for the first time that intensive insulin therapy could inhibit NF-jB expression and increase IjB expression in PBMCs of infants undergoing CPB. These changes are characteristic of an anti-inflammatory effect at the cellular and molecular level. Pro-inflammatory cytokines, such as IL-1, IL-6, or TNF, are balanced by anti-inflammatory cytokines, such as IL-2 and IL-10. Our study showed that the levels of pro-inflammatory cytokines were significantly lower in the intensive insulin therapy group after termination of CPB compared to the routine therapy group, while the levels of the anti-inflammatory cytokines were significantly higher in the intensive insulin therapy group after the termination of CPB. The mechanism may be as follows: hyperglycemia could promote the occurrence of oxidative stress, while control of blood glucose could reduce oxidative stress and inhibit NF-jB expression [17]. Additionally, insulin could modify the metabolism of free fatty acids, weakening the inflammation-promoting effects, and reduce the release of inflammatory mediators [24]. Furthermore, insulin could reduce the occurrence of oxidative stress, inhibit NADPH oxidase expression and the expression and adhesion of NF-jB in the cellular nucleus, activate IjB expression, followed by a decrease in the concentrations of plasminogen activator inhibitor-1, intercellular adhesion molecule-1, and monocyte chemoattractant protein-1 [6,12,25]. So, insulin may result in the reduction in the pro-inflammatory mediators by reducing blood glucose and by decreasing the release of pro-inflammatory mediators. In addition, hyperglycemia could directly cause cellular damage and water–electrolyte disturbances induced by tissue hypertonicity, reduce the immune function of the body, predispose to infection, and directly affect the operative outcome and patients’ prognosis. Therefore, strict blood glucose control has been a key treatment for acute and severe symptoms in postoperative patients [8,9]. In our study, the glucose levels in the routine therapy group were significantly increased after the initiation of CPB. In contrast, blood glucose levels were reasonably controlled in the intensive therapy group. The results of our study showed for the first time that intensive insulin therapy in infants undergoing cardiac surgery with CPB could control blood glucose levels, as well as attenuate the systemic inflammatory response by modifying the expression of pro-inflammatory and anti-inflammatory cytokines. It is suggested that intensive insulin therapy may represent an important and safe therapeutic option in the treatment of patients undergoing CPB.
Acknowledgments The work was supported by a grant from National Natural Science Foundation (No.30770802) of China, and a National Key Technology Research and Development Program (2006BAI01A08) from National Natural Science Foundation of China. References [1] Aebert H, Kirchner S, Keyser A, Birnbaum DE, Holler E, Andreesen R, et al. Endothelial apoptosis is induced by serum of patients after cardiopulmonary bypass. Eur J Cardiothorac Surg 2000;18:589–93. [2] Asahara T, Masuda H, Takahashi T, Kalka C, Pastore C, Silver M, et al. Bone marrow origin of endothelial progenitor cells responsible for postnatal vasculogenesis in physiological and pathological neovascularization. Circ Res 1999;85:221–8. [3] Wang H, Bloom O, Zhna M, Vishnubhakat JM, Ombrellino M, Che J, et al. HMG-1 as a late mediator of endotoxin lethality in mice. Science 1999;285:248–51. [4] Tracey KJ, Fong Y, Hesse DG, Manogue KR, Lee AT, Kuo GC, et al. Anti-cachectin/ TNF monoclonal antibodies prevent septic shock during lethal bacteraemia. Nature 1987;330:662–4. [5] Jeschke MG, Klein D, Bolder U, Einspanier R. Insulin attenuates the systemic inflammatory response in endotoxemic rats. Endocrinology 2004;145(9): 4084–93. [6] Dandona P, Aljada A, Mohanty P, Ghanim H, Hamouda W, Assian E, et al. Insulin inhibits intranuclear nuclear factor jB and stimulates IjB in mononuclear cells in obese subjects: evidence for an anti-inflammatory effect? J Clin Endocrinol Metab 2001;86:3257–65. [7] Baeuerle PA, Henkel T. Function and activation of NF-j B in the immune system. Annu Rev Immunol 1994;12:141–79. [8] Van den Berghe G, Wouters P, Weekers F, Verwaest C, Bruyninckx F, Schetz M, et al. Intensive insulin therapy in critically ill patients. N Engl J Med 2001;345:1359–67. [9] Van den Berghe G, Wilmer A, Hermans G, Meersseman W, Wouters PJ, Milants I, et al. Intensive insulin therapy in the medical ICU. N Engl J Med 2006;354(5):449–61. [10] Jeschke MG, Einspanier R, Klein D, Jauch KW. Insulin attenuates the systemic inflammatory response to thermal trauma. Mol Med 2002;8:443–50. [11] Jeschke MG, Klein D, Herndon DN. Insulin treatment improves the systemic inflammatory reaction and hepatic acute-phase-response to severe thermal injury. Ann Surg 2004;239:553–60. [12] Aljada A, Ghanim H, Mohanty P, Kapur N, Dandona P. Insulin inhibits the proinflammatory transcription factor early growth response gene-1 (Egr)-1 expression in mononuclear cells (MNC) and reduces plasma tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1) concentrations. J Clin Endocrinol Metab 2002;87:1419–22. [13] Furnary AP, Wu Y. Clinical effects of hyperglycemia in the cardiac surgery population: the Portland diabetic project. Endocr Pract 2006;12(Suppl. 3):22–6. [14] Liu Ya-Li, Bi Hui, Chi Su-Min, Fan Rong, Wang Yue-Min, Ma Xin-Liang, et al. The effect of compound nutrients on the stress-induced serum IL-2, IL-6 and TNF-a levels in rat. Cytokine 2007;37:14–21. [15] Golden SH, Peart-Vigilance C, Kao WH, Brancati FL. Perioperative glycemic control and the risk of infectious complications in a cohort of adults with diabetes. Diabetes Care 1999;22(9):1408–14. [16] Watarida S, Mori A, Onoe M, Tabata R, Shiraishi S, Sugita T, et al. A clinical study on the effects of pulsatile cardiopulmonary bypass on the blood endotoxin levels. J Thorac Cardiovasc Surg 1994;108:620–5. [17] Ha H, Yu MR, Choi YJ, Kitamura M, Lee HB. Role of high glucose-induced nuclear factor-kappaB activation in monocyte chemoattractant protein-1 expression by mesangial cells. Am Soc Nephrol 2002;13:894–902. [18] Beutler B, Milsark JM, Cerami A. Cachectin/tumor necrosis factor production distribution, and metabolic fate in vivo. J Immunol 1985;135:3972–7. [19] VanDamme J. In: Thomson A, editor. Interleukin-8 and related molecules. London: Academic Press Ltd.; 1991. p. 201–14. [20] Emanuelli B, Peraldi P, Filloux C, Sawka-Verhelle D, Hilton D Van Obberghen E. SOCS-3 is an insulin-induced negative regulator of insulin signalling. J Biol Chem 2000;275:15985–91. [21] Nelson PJ, Kim HT, Manning WC, Goralski TJ, Krensky AM. Genomic organization and transcriptional regulation of the RANTES chemokine gene. J Immunol 1993;151:2601–12. [22] Pruitt JH, Copeland EM, Moldawer LL. Interleukin-1 and interleukin-1 antagonism in sepsis systemic inflammatory response syndrome and septic shock. Shock 1999;3:235–51. [23] Alexander HR, Doherty GM, Buresh CM. A recombinant human receptor antagonist to interleukin-1 improves survival after lethal endotoxemia in mice. J Exp Med 1991;173:1029–32. [24] Tripathy D, Mohanty P, Dhindsa S, Syed T, Ghanim H, Aljada A, et al. Elevation of free fatty acids induces inflammation and impairs vascular reactivity in healthy subjects. Diabetes 2003;52:2882–7. [25] Dandona P, Aljada A, Mohanty P. The anti-inflammatory and potential antiatherogenic effect of insulin: a new paradigm. Diabetologia 2002;45:924–30.
Contents lists available at ScienceDirect
Cytokine journal homepage: www.elsevier.com/locate/issn/10434666
Effects of insulin therapy on inflammatory mediators in infants undergoing cardiac surgery with cardiopulmonary bypass Gu Chun-Hu a,1, Cui Qin a,1, Wang Yun-Ya b,1, Wang Jing b, Dou Ya-Wei a, Zhao Rong a, Liu Yang a, Wang Jin a, Pei Jian-Ming c,*, Yi Ding-Hua a,* a
Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, 15# Changle West Road, Xi’an 710032, Shaanxi, China Department of Nuclear Medicine, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, Shaanxi, China c Department of Physiology, National Key Discipline of Cell Biology, Fourth Military Medical University, 169# Changle West Road, Xi’an 710032, Shaanxi, China b
a r t i c l e
i n f o
Article history: Received 15 February 2008 Received in revised form 4 June 2008 Accepted 27 June 2008
Keywords: Insulin Cardiopulmonary bypass Interleukin Tumor necrosis factor Nuclear factor-jBp65 IjB
a b s t r a c t To determine whether insulin administration modulates the systemic inflammatory response in infants undergoing cardiac surgery with cardiopulmonary bypass, 60 infants undergoing cardiopulmonary bypass were randomly assigned into a routine therapy group or to an intensive insulin therapy group with 30 infants in each group. Plasma IL-1b, IL-6, IL-10, and TNF-a levels were determined before anesthesia, at the initiation of cardiopulmonary bypass, and at 0, 6, 12, 24, and 48 h after cardiopulmonary bypass. Nuclear factor-jBp65 expression and IjB expression in peripheral blood mononuclear cells were also measured by Western blot analysis. TNF-a, IL-1b, IL-6, and IL-10 levels were all elevated after the initiation of cardiopulmonary bypass. However, TNF-a, IL-1b, and IL-6 levels were significantly attenuated in the intensive insulin therapy group compared to those in the routine therapy group after initiation of cardiopulmonary bypass (p < 0.05 or <0.01). Meanwhile, plasma IL-10 levels were significantly higher in the intensive insulin therapy group than in the routine therapy group after initiation of cardiopulmonary bypass (p < 0.05 or <0.01). Accordingly, Nuclear factor-jBp65 expression and IjB expression were significantly increased after initiation of cardiopulmonary bypass in both groups (p < 0.05 or <0.01). The expression of Nuclear factor-jBp65, which induces the transcription of pro-inflammatory cytokines was significantly attenuated in the intensive insulin therapy group (p < 0.05 or <0.01). Meanwhile, the expression of IjB, an inhibitor of NF-jB, was significantly higher in the intensive insulin therapy group (p < 0.05 or <0.01). These results suggested that intensive insulin therapy may attenuate the systemic inflammatory response in infants undergoing cardiopulmonary bypass. Ó 2008 Published by Elsevier Ltd.
1. Introduction Cardiac surgery with cardiopulmonary bypass (CPB) provokes a systemic inflammatory response. This inflammatory reaction and injury may contribute to the development of postoperative complications [1,2]. The magnitude and duration of the systemic inflammatory response determines the development and degree of tissue damage, multiorgan failure, or even death [3,4]. The pathophysiological cascade is mediated by pro-inflammatory cytokines, such as IL-1b, IL-6, or TNF, that are potentially detrimental. Pro-inflammatory mediators are balanced by antiinflammatory cytokines, such as IL-2, IL-4, or IL-10 [5]. It has been shown that the expression and synthesis of pro- and anti-inflammatory cytokines are controlled by signal transcription factors [6].
* Corresponding authors. Fax: +86 29 83210092 (D.-H. Yi). E-mail addresses: [email protected] (J.-M. Pei), [email protected] (D.-H. Yi). 1 These authors contributed equally to this work. 1043-4666/$ - see front matter Ó 2008 Published by Elsevier Ltd. doi:10.1016/j.cyto.2008.06.014
The prime cellular signal of inflammation is the transcription factor, Nuclear factor kappaB (NF-jB), which induces the transcription of pro-inflammatory cytokines, adhesion molecules, and enzymes generating reactive oxygen species (ROS), and IjB is an inhibitor of NF-jB [7]. Despite recent advances in the understanding of the molecular cascade of the systemic inflammatory response, the lack of an effective treatment still remains a clinical problem. Insulin given at doses to maintain blood glucose at less than 110 mg/dL has been reported to decrease the incidence of complications and reduce the fatality rate in critically ill patients who require intensive care for more than five days and improve the patients’ prognosis [8,9]. The mechanisms by which insulin improves survival in critically ill patients have not been elucidated so far. Insulin has been shown to alter inflammatory mediators and improve liver morphology and function after a thermal injury [10,11]. In recent observations, insulin has been shown to suppress several pro-inflammatory transcription factors, such as Nuclear factor (NF)-jB, Egr-1, and activating protein-1 (AP-1) and the corresponding genes regulated by
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them, which mediate inflammation [6,12]. However, there are few studies on the mechanism and effects of intensive insulin therapy on inflammatory cytokines in patients during CPB, especially in infants. Therefore, the aim of the present study was to determine whether insulin administration modulates the systemic inflammatory response in infants undergoing CPB.
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blood glucose of 2.8–3.3 mmol/L. When the blood glucose level was below 2.8 mmol/L, insulin infusion was discontinued, and 10 mL of 20% glucose was infused intravenously. (4) Insulin was discontinued when rewarming. (5) The postoperative blood glucose level was adjusted to ‘U/kg/h’ by the schedule of Ref. [13]. 2.3. Determination of insulin, IL-1b, IL-6, IL-10, and TNF-a
2. Methods 2.1. Patients The study was approved by our Local Ethics Committee. Anonymous data acquisition and data publication are in accordance with the Declaration of Helsinki. Preoperatively all the infants’ parents received detailed information on the insulin therapy and gave their written consent. Sixty infants undergoing cardiac surgery with CPB for congenital heart disease were enrolled at our hospital from August 2006 to January 2007. None of the infants had a history of diabetes mellitus. These infants were randomly divided into a routine therapy group (n = 30) and an intensive insulin therapy group (n = 30). The patient characteristics are summarized in Table 1. No significant difference was found in age, sex, body weight, or any other operative procedure between the two groups (Table 1). Exclusive criteria included: preoperative liver and kidney disease or dysfunction, preoperative coagulation disorder, palliative operation or second operation, or impairment of blood glucose control. 2.2. Blood glucose control Blood glucose levels were 4.4–10.0 mmol/L during the operation and 4.4–8.3 mmol/L after the operation in the intensive insulin therapy group. Changes in blood glucose levels were not controlled in the routine therapy group. Patients in the routine therapy group received standard institutional operative and postoperative care. For the intensive insulin therapy group, the intraoperative schedule was as follows. (1) Insulin was infused into the central vein of infants at 0.2 U/kg/h with a micro pump after anesthesia. (2) The flow rate was adjusted to 0.5 U/kg/h after the infants underwent thoracotomy. (3) The flow rate was adjusted to 1.5–2 U/kg/ h when IL was determined. Blood glucose was measured every 15 min. The insulin infusion was regulated as follows. The flow rate would be increased by 0.2 U/kg/h for 8.9–9.4 blood glucose of mmol/L; increased by 0.4 U/kg/h for blood glucose of 9.4– 10.0 mmol/L; increased by 0.6 U/kg/h for blood glucose over 10.0 mmol/L. The flow rate would be decreased by 0.2 U/kg/h for blood glucose of 3.3–3.9 mmol/L; decreased by 0.5 U/kg/h for
Table 1 Baseline characteristics and operative data of infants Data
IT group (n = 30)
RT group (n = 30)
Male gender (%) Age (year) Body weight (kg) Left ventricular ejection fraction (%) Cardiopulmonary bypass time (min) Cross-clamping time (min) Cardiopulmonary bypass -flow (L/min/m2) Ultrafiltration (mL/kg) Insulin (lU/mL) Blood glucose level (mmol/L) Tumor necrosis factor-a (pg/mL) Interleukin-1b (pg/mL) Interleukin-6 (pg/mL) Interleukin-10 (pg/mL)
18 (60) 1.4 ± 0.5 5.7 ± 2.0 66.0 ± 7.2 55.2 ± 3.9 31.6 ± 2.4 2.9 ± 0.3 342 ± 35 7.9 ± 1.6 4.5 ± 0.6 31.9 ± 2.5 6.3 ± 1.2 18.9 ± 3.7 50.9 ± 3.6
16 (53) 1.6 ± 0.4 6.2 ± 1.6 64.5 ± 5.1 58.1 ± 2.8 32.4 ± 3.8 3.0 ± 0.2 334 ± 32 8.3 ± 1.6 4.3 ± 0.8 32.3 ± 3.2 6.2 ± 1.5 21.2 ± 2.5 46.6 ± 4.6
Data are presented as the number (%) of patients or mean values ± SD. RT group, routine therapy group; IT group, intensive insulin therapy group.
Blood samples were taken in heparinized tubes at 7 time points for each patient as follows: before surgical anesthesia (T1), at the initiation of CPB (T2), at the termination of CPB (T3), 6 h after CPB (T4), 12 h after CPB (T5), 24 h after CPB (T6), and 48 h after CPB (T7). Plasma insulin levels were measured in all infants of the two groups with an Insulin Kit (R&D Systems, Abingdon, UK). Plasma IL-6, IL-8, IL-10, as well as TNF-a levels were determined using commercially available ELISA kits (R&D Systems, Abingdon, UK) as our previous study documented [14]. All enzyme-linked immunoabsorption assay (ELISA) protocols were carried out according to kit guidelines. Results of the measurements were corrected according to the following formula: Taking an example of the haematocrit, the corrected value is equal to the actual measure (1 haematocrit sample level)/(1 haematocrit level before anesthesia). 2.4. Peripheral blood mononuclear cell isolation from blood samples Blood samples were collected in Na–EDTA as an anticoagulant. Anticoagulant-treated blood was thoroughly mixed with Hanks’ solution (1:1) and layered on Ficoll-Paque solution and centrifuged at 800g for 15 min at 20 °C. First, the upper layer of plasma was discarded. Then the lymphocyte layer was transferred to a clean centrifuge tube containing 4–5 mL Hanks’ solution and centrifuged at 800g for 10 min. The upper layer was discarded. Two washing steps followed, adding three volumes of Hanks’ solution and centrifugation at 800g for 10 min at 20 °C. The supernatant was removed, and the peripheral blood mononuclear cells (PBMCs) in the pellets were reconstituted to a concentration of 4 105 cells/ mL in Hanks’ solution. 2.5. Western blot PBMC lysates were prepared by adding 1 mL boiling lysis buffer (1% SDS), 1 mm sodium ortho-vanadate, 10 mm Tris (pH 7.4) to the PBMC pellet. The protein concentration was quantitated with the BCA protein quantitation kit (Pierce, USA). Sixty micrograms of total cell lysate were electrophoresed on 12% SDS for NF-jBp65 or 15% SDS for IjB. Protein was isolated by SDS/PGEA electrophoresis, transferred onto polyvinylidene difluoride (Bio-Rad Laboratories, USA) by the semi-dry electrophoretic transfer technique, blocked with 5% skimmed milk, and incubated with polyclonal antibody against IkB (Sigma, USA) or a monoclonal antibody against NF-jBp65 (Sigma, USA) overnight at 4 °C, and then incubated with the corresponding second antibody at room temperature for 1 h after washing the membranes. An immunodetection kit was used for fluorescence detection (Pierce, USA). 2.6. Statistical analysis Measurements were presented as means ± SD. Statistical analysis was performed using SPSS 11.0 software. Standard methods were used, as indicated in the figure legends and tables—for example, repeated measures analysis of variance (ANOVA) models and ordinary ANOVA models (see Section 3) (Figs. 1–4), and t-tests (Table 1). A value of p < 0.05 was considered statistically significant.
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Fig. 1. Changes in blood glucose levels and insulin levels in the perioperative period. *p < 0.05, **p < 0.01 compared with basal levels. #p < 0.05, ##p < 0.01 compared with RT group. The error bars are the standard deviation (CPB, cardiopulmonary bypass; RT group, routine therapy group; IT group, intensive insulin therapy group; T, time; T1, before anesthesia; T2, initiation of CPB; T3, termination of CPB; T4, 6 h after CPB; T5, 12 h after CPB; T6, 24 h after CPB; T7, 48 h after CPB.).
Fig. 2. Pre and postoperative interleukins. *p < 0.05, **p < 0.01 compared with basal levels. #p < 0.05, ##p < 0.01 compared with RT group. The error bars are the standard deviation. IL-1b, IL-6, and TNF-a levels are higher than basal levels and did not normalize within the study period in the RT group (A–C). However, there was no significant difference in IL-10 levels between the RT group and IT group (IL, interleukins; TNF, tumor necrosis factor-a; CPB, cardiopulmonary bypass; RT group, routine therapy group; IT group, intensive insulin therapy group; T, time; T1, before anesthesia; T2, initiation of CPB; T3, termination of CPB; T4, 6 h after CPB; T5, 12 h after CPB; T6, 24 h after CPB; T7, 48 h after CPB.).
3. Results 3.1. Changes in blood glucose level and insulin levels After anesthesia, there was a biphasic response of blood glucose levels in the routine group (Fig. 1A). The first phase consisted of an
increase in blood glucose levels 1.7-fold at the initiation of CPB and 3.1-fold at the end of CPB, relative to the preoperative baseline level, respectively. The blood glucose level transiently decreased to 2.7-fold the baseline level 6 h after CPB. The second phase of the increase in blood glucose levels occurred 12 h after CPB, then continuously decreased, but did not reach the preoperative level
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therapy group than in the routine therapy group at each time point after CPB (p < 0.05 or 0.01). 3.2. Changes in plasma IL-1b, IL-6, TNF-a, and IL-10 levels
Fig. 3. Changes in NF-jBp65 expression in peripheral blood mononuclear cells. * p < 0.05, **p < 0.01 compared with basal levels. #p < 0.05, ##p < 0.01 compared with RT group. (A) Representative Western blot showing the increase in NF-jBp65 quantity in peripheral blood mononuclear cell homogenates following routine therapy (upper gel) or intensive insulin therapy (lower gel). (B) Densitometric quantitative analysis of NF-jBp65 protein content (CPB, cardiopulmonary bypass; RT group, routine therapy group; IT group, intensive insulin therapy group; NF-jBp65, Nuclear factor jBp65; T, time; T1, before anesthesia; T2, initiation of CPB; T3, termination of CPB; T4, 6 h after CPB; T5, 12 h after CPB; T6, 24 h after CPB; T7, 48 h after CPB.).
The pro-inflammatory cytokines TNF-a, IL-1b, and IL-6 showed a monophasic response in both groups (Fig. 2A–C). Samples from the routine therapy group showed a 2.7-fold increase for TNF-a, a 6.6-fold increase for IL-1b, and a 7.6-fold increase for IL-6 6 h after CPB, then a decrease, although not back to the preoperative level 48 h after CPB (Fig. 2A–C). Although the monophasic response of TNF-a, IL-1b, and IL-6 was similar in both groups, the levels remained significantly higher in the routine therapy group compared with the intensive insulin therapy group at each time point after the initiation of CPB (p < 0.05 or 0.01) (Fig. 2A–C). Anti-inflammatory cytokine IL-10 levels were elevated immediately after CPB, and reached a peak at 12 h after CPB, then decreased, but did not reach the preoperative level 48 h after CPB in either group. IL-10 levels were significantly higher in the insulin therapy group than in the routine therapy group at each time point after the termination of CPB (p < 0.05 or 0.01) (Fig. 2D). 3.3. Changes in NF-jBp65 and IjB expression in the PBMCs Fig. 3A shows a representative Western blot of NF-jBp65 expression in the two groups. NF-jBp65 in PBMCs were increased significantly after the termination of CPB in both groups, with a peak at 6 h after CPB (252 ± 52% of the basal level for the routine therapy group, 395 ± 102% of the basal level for the insulin therapy group), then they decreased, but did not reach the preoperative level 48 h after CPB in either group. NF-jBp65 expression was significantly lower in insulin therapy group than in the routine therapy group after the termination of CPB (p < 0.05 or 0.01) (Fig. 3B). Fig. 4A shows a representative Western blot of IjB expression in the two groups. IjB protein levels in PBMCs in the insulin therapy group increased significantly to 172 ± 30% at the end of CPB, peaked at 6 h after CPB (332 ± 100% of the basal level) and declined at 12 h after CPB, but did not reach the preoperative level 48 h after CPB. IjB expression was significantly higher in the insulin therapy group than in the routine therapy group at each time point after the termination of CPB (p < 0.05 or 0.01). (Fig. 4B). 3.4. Clinical results
Fig. 4. Changes in IjB expression in the peripheral blood mononuclear cells. * p < 0.05, **p < 0.01 compared with basal levels. #p < 0.05, ##p < 0.01 compared with RT group. (A) Representative Western blot showing the increase in IjB in peripheral blood mononuclear cell homogenates following routine therapy (upper gel) or intensive insulin therapy (lower gel). (B) Densitometric quantitative analysis of IjB protein content (CPB, cardiopulmonary bypass; RT group, routine therapy group; IT group, intensive insulin therapy group; T, time; T1, before anesthesia; T2, initiation of CPB; T3, termination of CPB; T4, 6 h after CPB; T5, 12 h after CPB; T6, 24 h after CPB; T7, 48 h after CPB.).
All the patients survived. The duration of postoperative mechanical ventilation was 7.2 ± 1.6 h in the control group and 10.3 ± 1.8 h in the intensive insulin therapy group (p < 0.05). The length of stay in the intensive care unit was 65.3 ± 12.1 h in the routine therapy group and 48.9 ± 12.9 h in the intensive insulin therapy group (p < 0.05).
at 48 h after CPB. Blood glucose levels were reasonably controlled in the intensive insulin therapy group. Blood glucose levels were significantly higher in the routine group than in the intensive insulin therapy group at each time point after initiation of CPB (p < 0.05 or 0.01) (Fig. 1A). An apparently similar biphasic response could be observed for plasma levels of insulin in both groups (Fig. 1B). After a first increase 0 h postoperatively (4.6-fold for the intensive therapy group and 2.6-fold for the routine therapy group), plasma insulin levels declined transiently in both groups after 6 h, but the second phase of increase after 12 h was not as marked as the first phase (Fig. 1B). Insulin levels were significantly higher in the intensive insulin
Many studies have verified that intensive insulin therapy could improve the prognosis of severe diseases, especially cardiovascular disease [7,8,15]. However, its mode of action has not been clearly identified so far. This study investigated the effects of intensive insulin therapy on pro-inflammatory cytokines, anti-inflammatory cytokines levels, and the expression of NF-jBp65 and IjB in the PBMCs in infants undergoing CPB. CPB provokes a systemic inflammatory response. This inflammatory reaction and injury may contribute to the development of postoperative complications. Our study showed that TNF-a, IL-1b, IL-6 levels, and NF-jB expression were significantly increased after the initiation of CPB in both groups. Several factors
4. Discussion
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may contribute to such problems. First, CPB could activate the complement system and produce anaphylatoxin that could activate neutrophils, macrophages, and monocytes. Second, CPB always causes stress hyperglycemia because of anesthesia, operation, postoperative pain, dysphoria of patients, use of assisted ventilation, and so on [16]. Hyperglycemia could promote oxidative stress and induce Nuclear factor-jB activation [17]. Additionally CPB could impair the barrier function of the digestive tract, allowing bacteria into the blood circulation, resulting in endotoxemia [16]. Endotoxins could generate TNF by activating macrophages and monocytes [16,18]. Furthermore, interaction of various cytokines occurs [19]. TNF-a, IL-1, and IL-6 generated in the early inflammatory reaction could trigger an inflammatory reaction and amplify the inflammatory process [14]. Activated TNF-a could reactivate NF-jB and cause the excessive activation of Nuclear factor jB. Peripheral blood mononuclear cells are cellular mediators of inflammation. The prime cellular signal of inflammation is the transcription factor, NF-jB, that leads to the transcription of proinflammatory cytokines and adhesion molecules and to enzymatic mechanisms that cause generation of reactive oxygen species (ROS) [20,21]. IjB binds to cytosolic NF-jB and prevents its translocation into the nucleus [22,23]. Our data showed for the first time that intensive insulin therapy could inhibit NF-jB expression and increase IjB expression in PBMCs of infants undergoing CPB. These changes are characteristic of an anti-inflammatory effect at the cellular and molecular level. Pro-inflammatory cytokines, such as IL-1, IL-6, or TNF, are balanced by anti-inflammatory cytokines, such as IL-2 and IL-10. Our study showed that the levels of pro-inflammatory cytokines were significantly lower in the intensive insulin therapy group after termination of CPB compared to the routine therapy group, while the levels of the anti-inflammatory cytokines were significantly higher in the intensive insulin therapy group after the termination of CPB. The mechanism may be as follows: hyperglycemia could promote the occurrence of oxidative stress, while control of blood glucose could reduce oxidative stress and inhibit NF-jB expression [17]. Additionally, insulin could modify the metabolism of free fatty acids, weakening the inflammation-promoting effects, and reduce the release of inflammatory mediators [24]. Furthermore, insulin could reduce the occurrence of oxidative stress, inhibit NADPH oxidase expression and the expression and adhesion of NF-jB in the cellular nucleus, activate IjB expression, followed by a decrease in the concentrations of plasminogen activator inhibitor-1, intercellular adhesion molecule-1, and monocyte chemoattractant protein-1 [6,12,25]. So, insulin may result in the reduction in the pro-inflammatory mediators by reducing blood glucose and by decreasing the release of pro-inflammatory mediators. In addition, hyperglycemia could directly cause cellular damage and water–electrolyte disturbances induced by tissue hypertonicity, reduce the immune function of the body, predispose to infection, and directly affect the operative outcome and patients’ prognosis. Therefore, strict blood glucose control has been a key treatment for acute and severe symptoms in postoperative patients [8,9]. In our study, the glucose levels in the routine therapy group were significantly increased after the initiation of CPB. In contrast, blood glucose levels were reasonably controlled in the intensive therapy group. The results of our study showed for the first time that intensive insulin therapy in infants undergoing cardiac surgery with CPB could control blood glucose levels, as well as attenuate the systemic inflammatory response by modifying the expression of pro-inflammatory and anti-inflammatory cytokines. It is suggested that intensive insulin therapy may represent an important and safe therapeutic option in the treatment of patients undergoing CPB.
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