Higher cytotoxic activity and increased levels of IL-1 beta, IL-6, and TNF-alpha in patients undergoing cardiopulmonary bypass

Impact of IL1B gene polymorphisms and interleukin 1B levels on susceptibility to spontaneous preterm birth

OBJECTIVE

Genetic factors influence susceptibility to preterm birth (PTB) and the immune pathway of PTB that involves the production of cytokines such as interleukins has been implicated in PTB disease. The aim of this study is to investigate the association of interleukin 1β (IL1B) gene polymorphisms and IL1B levels with spontaneous PTB.

STUDY DESIGN

Peripheral maternal blood from 495 women was used for extraction of DNA and genotyping was carried out using the Sequenom MassARRAY platform. Maternal plasma was used to measure IL1B levels.

RESULTS

There was no significant association between the allelic and genotype distribution of IL1B single nucleotide polymorphism (SNP) (rs1143634, rs1143627, rs16944) and the risk of PTB among Malaysian Malay women (rs1143634, P=0.722; rs1143627, P=0.543; rs16944, P=0.615). However, IL1B levels were significantly different between women who delivered preterm compared with those who delivered at term (P=0.030); high mean levels were observed among Malay women who delivered at preterm (mean=32.52) compared with term (mean=21.68). IL1B SNPs were not associated with IL1B plasma levels.

CONCLUSION

This study indicates a significant association between IL1B levels and reduced risk of PTB among the Malaysian Malay women. This study shows the impact of IL1B levels on susceptibility to PTB disease; however, the high levels of IL1B observed among women in the preterm group are not associated with IL1B SNPs investigated in this study; IL1B high levels may be because of other factors not explored in this study and therefore warrant further investigation.

Continuous renal replacement therapy to reduce inflammation in a piglet hemorrhage-reperfusion extracorporeal membrane oxygenation model

BACKGROUND

During extracorporeal membrane oxygenation (ECMO), circulation of blood across synthetic surfaces triggers an inflammatory response. Therefore, we evaluated the ability of continuous renal replacement therapy (CRRT) to remove cytokines and reduce the inflammatory response in a piglet hemorrhage-reperfusion ECMO model.

METHODS

Three groups were studied: (i) uninjured controls (n = 11); (ii) hemorrhage-reperfusion while on venoarterial ECMO (30% hemorrhage with subsequent blood volume replacement within 60 min) (n = 8); (iii) treatment with CRRT after hemorrhage-reperfusion while on ECMO (n = 7). Hemodynamic parameters, oxygen utilization, and plasma and broncho-alveolar lavage (BAL) cytokine levels were recorded and lung tissue samples collected for histologic comparison.

RESULTS

Whereas mean arterial pressures decreased among hemorrhage-reperfusion piglets, ECMO with CRRT did not significantly alter mean arterial pressures or systemic vascular resistance and was able to maintain blood flow as well as oxygen delivery after hemorrhage-reperfusion. Plasma interleukin (IL)-6 and IL-10, and BAL tumor necrosis factor (TNF)-α, IL-1β, IL-6, IL-8, and IL-10 increased as a result of hemorrhage-reperfusion while on ECMO. After a 6-h period of CRRT, plasma IL-6 and BAL TNF-α, IL-6, and IL-8 levels decreased.

CONCLUSION

Data suggest CRRT may decrease inflammatory cytokine levels during the initial phase of ECMO therapy following hemorrhage-reperfusion while maintaining cardiac output and oxygen utilization.

Surgical trauma affects the proinflammatory status after cardiac surgery to a higher degree than cardiopulmonary bypass

OBJECTIVES

Cytokines contribute to the development of the systemic inflammatory response syndrome or multiple-organ failure frequently observed after cardiopulmonary bypass-supported cardiac surgery. To quantify the contribution of bypass-induced versus trauma-induced inflammatory response after coronary artery bypass grafting, we examined plasma cytokine levels in 120 patients with coronary artery disease who were treated with or without cardiopulmonary bypass-assisted procedures.

METHODS

Patients were treated in accordance with one of the following protocols: (1) elective percutaneous coronary intervention without cardiopulmonary bypass (n = 69), (2) cardiopulmonary bypass-supported percutaneous coronary intervention (cardiopulmonary bypass-percutaneous coronary intervention; n = 10), and (3) cardiopulmonary bypass-supported coronary artery bypass grafting (cardiopulmonary bypass-coronary artery bypass grafting; n = 41). Cytokine levels (picograms/milliliter) were measured by enzyme-linked immunosorbent assay from plasma samples obtained at various time points.

RESULTS

Interleukin-6 was measured in blood samples from all 3 patient populations. The maximum interleukin-6 level was 13.6 +/- 22.3 pg/mL in the percutaneous coronary intervention group, 170.4 +/- 165.4 pg/mL in the cardiopulmonary bypass-percutaneous coronary intervention group, and 640.3 +/- 285.7 pg/mL in the cardiopulmonary bypass-coronary artery bypass grafting group. Interleukin-6 levels were significantly different, and the 95% confidence intervals did not overlap. In the cardiopulmonary bypass-percutaneous coronary intervention group, bypass duration correlated well with interleukin-6 production ( r = 0.915; P < .001), whereas these parameters did not correlate in patients who underwent cardiopulmonary bypass-coronary artery bypass grafting ( r = 0.307; P = .054).

CONCLUSIONS

These findings support the suggestion that surgical trauma and cardiopulmonary bypass contribute to the inflammatory response after cardiac surgery, although trauma may contribute to a higher degree.

Cytokine response to endotoxin in individuals heterozygous for the Delta32 mutation of chemokine receptor CCR5

Studies of mice with a targeted disruption of the CCR5 gene suggest that the CC chemokine receptor 5 (CCR5) is a determinant of the cytokine response to endotoxin. In humans, a naturally occurring mutation of the CCR5 gene is a 32-basepair (bp) deletion which precludes the translation of the gene into a functional transmembrane protein. To evaluate the cytokine phenotype of heterozygosity for the 32 deletion, we studied the endotoxin-stimulated release of tumor necrosis factor-alpha, Interleukin (IL)-6, IL-8, IL-10, and IL-12 in whole blood ex-vivo of healthy volunteers and patients undergoing elective cardiac bypass surgery. This operation represents a major surgical trauma associated with ischemia-reperfusion-injury and triggers a profound inflammatory response. In these patients, cytokine plasma concentrations were measured during and after cardiac surgery. No difference was found between the frequencies of the observed and expected CCR5 genotypes in the groups of individuals studied. Furthermore, no significant difference in ex-vivo or peri- and postoperative cytokine plasma concentrations was detected between CCR5 wild-type homozygotes and individuals carrying one defective CCR5 allele. Our results indicate that heterozygosity for the 32bp deletion of CCR5 is not associated with an altered cytokine response to endotoxin or to a major surgical trauma when compared with individuals homozygous for the wild-type allele.

Tumor necrosis factor and clinical and metabolic courses after cardiac surgery in children

OBJECTIVE

This study was undertaken to determine the relationship between plasma tumor necrosis factor concentrations and hemodynamic and metabolic parameters during the postoperative clinical course in children undergoing cardiac surgery.

METHODS

Tumor necrosis factor levels of 10 consecutive children undergoing surgery for repair of congenital heart defects were analyzed in blood samples drawn at predetermined time points during surgery and up to 24 hours thereafter. Clinical data were collected at these times for correlation to tumor necrosis factor levels.

RESULTS

All the patients survived. Tumor necrosis factor was detected in all 10 children. Tumor necrosis factor levels declined after induction of general anesthesia (201 +/- 65 pg/mL) steadily decreasing during surgery, reaching 80 +/- 50 pg/mL at 24 hours after the operation. Tumor necrosis factor levels were found to be inversely correlated with mean blood pressure values and indicators of acidosis (bicarbonate levels and base excess, P <.03). They were not correlated with the durations of cardiopulmonary bypass and aortic crossclamping.

CONCLUSIONS

Tumor necrosis factor released into the circulation during and after pediatric cardiac surgery under cardiopulmonary bypass may be related to the hemodynamic and acid-base changes observed after cardiac surgery. Elucidation of the relationship between tumor necrosis factor and patient outcome in high-risk patients awaits further studies.

Inter-individual differences in cytokine release in patients undergoing cardiac surgery with cardiopulmonary bypass

Cardiac surgery with cardiopulmonary bypass (CPB) leads to a systemic inflammatory response with secretion of cytokines (e.g. IL-6, TNF-alpha, IL-1 beta and sIL-2R). The objective of the following study was to investigate in vitro and in vivo cytokine responses and white blood cell counts (WBC) of patients with high versus low cytokine secretion after a coronary artery bypass grafting (CABG) procedure. Twenty male patients undergoing elective CABG surgery with CPB under general anaesthesia were enrolled in the study. On the day of surgery (postoperatively), serum levels of TNF-alpha and IL-1 beta were significantly higher in patients of the high IL-6 level group compared to the respective values in the patient group with low IL-6 levels. The inter-individual differences in IL-6 release in patients undergoing CABG surgery with CPB were accompanied by differences in the release of other cytokines, such as TNF-alpha, IL-1 beta and sIL-2R. To understand whether genetic background plays a role in influencing cytokine plasma levels under surgical stress, we examined the distribution of polymorphic elements within the promoter regions of the TNF-alpha and IL-6 genes, and determined their genotype regarding the BAT2 gene and TNF-beta intron polymorphisms. Our preliminary data suggests that regulatory polymorphisms in or near the TNF locus, more precisely the allele set 140/150 of the BAT2 microsatellite marker combined with the G allele at -308 of the TNF-alpha gene, could be one of the genetic constructions providing for a less sensitive response to various stimuli. Our results suggest: (1) close relationships between cytokine release in the postoperative period, and (2) inter-individually varying patterns of cytokine release in patients undergoing CABG surgery with CPB.

Plasma concentrations of soluble tumor necrosis factor receptor I and tumor necrosis factor during cardiopulmonary bypass

BACKGROUND

Tumor necrosis factor-alpha (TNF) has been implicated in the development of postoperative morbidity after cardiopulmonary bypass for myocardial revascularization. Despite their postulated roles as modulators of TNF bioavailability, soluble TNF receptors have not been characterized in patients undergoing this procedure and is the focus of this study.

METHODS

Soluble tumor necrosis factor receptor I (sTNFRI) and TNF were measured by immunoassay in plasma samples collected from 36 patients at events before, during, and after cardiopulmonary bypass.

RESULTS

Plasma concentrations of sTNFRI averaged 1.39 ng/mL at the start of the operation. Preoperative sTNFRI concentrations were found to significantly correlate with a preoperative morbidity assessment score, age, duration of bypass, duration of supplemental oxygen, and length of hospital stay. Plasma sTNFRI increased in all of the patients during the procedure. Plasma concentrations of sTNFRI and TNF did not correlate at any time.

CONCLUSIONS

Preoperative measurement of sTNFRI could potentially serve as a reliable indicator for prophylactic treatment with an anti-TNF therapy. Such a therapeutic approach might help attenuate inflammatory processes thought to underlie postoperative morbidity associated with cardiopulmonary bypass.

Apoptosis of peripheral blood lymphocytes is induced by catecholamines

We explored the mechanism through which patients sometimes show immunosuppression after cardiac surgery. To test the hypothesis that commonly used drugs could cause apoptosis of immune cells, the proapoptotic effects of heparin and catecholamines (dopamine and dobutamine) on peripheral blood lymphocytes were evaluated. Peripheral blood lymphocytes were purified from blood samples of normal healthy volunteers. These cells were cultured in the presence of heparin, dobutamine or dopamine. The apoptosis was quantified by Annexin V fluorescent assay, by DNA content and by morphological assessment. Lymphocytes did not show significant levels of apoptosis induction after 24 hours of incubation with heparin. Both dopamine and dobutamine demonstrated a clear apoptosis inducing effect on lymphocytic population after 24 and 48 hours of culture, in concentrations comparable with the clinically used levels. Apoptosis was time and concentration dependent for both catecholamines. The dopamine and dobutamine effect on lymphocyte viability was due, at least partially, to lymphocyte beta receptor engagement, as proved by blocking the receptor with propranolol. These results suggest that catecholamines could induce apoptosis of lymphocytes. This finding may be associated with immunosuppression observed in patients undergoing cardiac surgery.

Perioperative serum levels of tumour-necrosis-factor alpha (TNF-alpha), IL-1 beta, IL-6, IL-10 and soluble IL-2 receptor in patients undergoing cardiac surgery with cardiopulmonary bypass without and with correction for haemodilution

Cardiac surgery with cardiopulmonary bypass (CPB) leads to a systemic inflammatory response with secretion of cytokines. Alterations in the serum concentrations of cytokines have important prognostic significance. Reports on cytokine release during cardiac surgery with CPB have yielded conflicting results. Haemodilution occurs with the onset of CPB resulting in large fluid shifts during the perioperative course of cardiac procedures. In the present study we compare the perioperative course of serum concentrations of TNF-alpha, IL-1beta, IL-6, IL-10 and sIL-2R with and without correction for haemodilution in patients undergoing coronary artery bypass grafting (CABG) surgery. Twenty male patients undergoing elective CABG surgery with CPB and general anaesthesia using a balanced technique with sufentanil, isoflurane and midazolam were enrolled into the study. Serum levels of TNF-alpha, IL-1beta, IL-6, IL-10 and sIL-2R were measured using commercially available ELISA kits. Simultaneous haematocrit values were obtained at all sample times. Statistical analysis was performed by non-parametric analysis of variance and t-tests for data corrected for haemodilution and data that were not corrected for haemodilution. Adjusted significance level was P < 0.01. Intra-operatively, up to the second post-operative day PCV values were significantly decreased compared with preoperative values. Cytokine measurements not corrected for haemodilution were significantly lower than the corrected values. The perioperative haemodilution and decrease in PCV may lead to an underestimation of the cytokine secretion in post-operative patients. We conclude that cytokine measurements were significantly influenced by the perioperative haemodilution and the subsequent decrease in PCV and may in part account for the varying results reported in the literature regarding cytokine release in patients undergoing CABG surgery.

Induced cell trauma during in vitro perfusion: a comparison between two different perfusion systems

The purpose of this study was to compare blood cell activation during in vitro long-term perfusion using 2 parallel in vitro extracorporeal membrane oxygenation (ECMO) systems. We compared two substantially different perfusion systems, an assistance respiratoire extra corporelle (AREC) system on one hand, containing an AREC pump, silicon tubing, and a hollow-fiber oxygenator, and a centrifugal pump system, on the other hand, containing a Biomedicus centrifugal pump, PVC tubing, and a membrane oxygenator. We measured the platelet count using an automated blood cell counter. Platelet activation was evaluated using a flow cytometric technique for the platelet membrane expression of glycoproteins and ELISA for the plasma concentration of beta-thromboglobulin (beta-TG), a platelet specific protein released into the blood upon platelet activation. The neutrophil count was assayed using an automated blood cell counter and the plasma concentration of cytokines using an ELISA kit. A significant difference between the two systems was observed in terms of the platelet membrane expression of glycoprotein (GP)Ib (p=0.0001) and GPIIb/IIIa (p=0.0037), indicating a lower degree of platelet activation in the AREC system. The concentration of neutrophils was significantly lower in the centrifugal system (p=0.002) compared to the AREC system. The neutrophil membrane expression of CD11b was significantly lower (p=0.0067) in the AREC system, indicating a lower degree of neutrophil activation compared to the centrifugal pump system. A significantly lower degree of hemolysis, as expressed by plasma hemoglobin, was observed in the AREC pump system (p=0.0491). In conclusion, lower degrees of the platelet membrane expression of GPIb and GPIIb/IIIa and of the neutrophil membrane expression of CD11b were observed in the AREC system, indicating a lower degree of platelet and neutrophil activation in this system. No significant difference between the two systems as to the plasma concentration of interleukin (IL)-1beta, IL-6, or IL-8 could be recorded. Further studies are warranted to specify the role of each individual component of the two systems.

Cytokine release during long-term extracorporeal circulation in an experimental model

The objective of this study was to determine the degree of leukocyte activation, as measured by cytokine release, in circulating blood during experimental extracorporeal circulation. Complete in vitro extracorporeal membrane oxygenation (ECMO) circuits were used, and 9 experiments were performed. Whole blood stored at 37 degrees C was used as the control. Blood samples were withdrawn before the start of perfusion and at 24 h of perfusion. Statistically significant releases of interleukin (IL)-1beta, IL-8, and IL-1 receptor antagonist were observed in the perfusion circuits compared to both the control blood and baseline values. Also, increases in plasma tumor necrosis factor (TNF)alpha and IL-6 were seen after 24 h of perfusion although these changes did not reach statistical significance. These results indicate that extracorporeal circulation induced leukocyte activation and cytokine release. These reactions might, as an additional trauma, deteriorate the situation in an already severely ill patient. A search for methods to counteract this untoward activation seems warranted.

Circulating endotoxin and cytokines after cardiopulmonary bypass: differential correlation with duration of bypass and systemic inflammatory response/multiple organ dysfunction syndromes

Cardiopulmonary bypass constitutes an injury that may cause postoperative pathophysiological changes due to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). These complications include coagulopathy, hypotension, capillary leakage, and multiple organ injury. To investigate the role of endotoxin and cytokines in the response to bypass injury, we measured plasma levels of endotoxin and proinflammatory cytokines in 20 pediatric patients before and after bypass. Clinical data, including duration of injury and tests indicative of SIRS/MODS, were collected. Levels of endotoxin, TNF-alpha, IL-6, and IL-8 but not IL-1 beta were significantly increased after bypass. Most of the cytokines have been found to correlate with each other. Endotoxin did not correlate with duration of bypass, cytokines, or SIRS/MODS. In contrast, TNF-alpha and IL-8 correlated with duration of bypass and were associated with SIRS/MODS. Certain clinical complications were associated with specific cytokines. Understanding the role of cytokinemia in SIRS/MODS may lead to better prognostic assessment and therapeutic modalities.