Induction of interleukin-8 messenger RNA in heart and skeletal muscle during pediatric cardiopulmonary bypass

Total Liquid Ventilation Reduces Lung Injury in Piglets After Cardiopulmonary Bypass

BACKGROUND

Cardiopulmonary bypass may cause lung injury that does not respond to traditional therapies. Total liquid ventilation has been developed as an alternative ventilatory strategy for severe lung injury. The aim of this study is to investigate the effect of total liquid ventilation on lung injury in piglets after cardiopulmonary bypass.

METHODS

After exposure to 60 minutes of cardiac arrest and weaning from cardiopulmonary bypass, 12 piglets (4.2 +/- 0.3 kg) were randomly treated with conventional gas ventilation (control group) or total liquid ventilation (study group) for 240 minutes. Samples for blood gas analysis were collected before, and at 30-minute intervals after, cardiopulmonary bypass. The degree of lung injury was quantified by histologic examination. The inflammatory cells and the levels of interleukin-6, interleukin-8, and myeloperoxidase in bronchoalveolar lavage were analyzed.

RESULTS

Neutrophil and macrophage count in bronchoalveolar lavage were significantly decreased in the study group (52.4 +/- 6.82 vs 0.46 +/- 0.11 10(4)/mL; 58.33 +/- 0.88 vs 4.37 +/- 0.90 10(5)/mL; p < 0.001, respectively). The inflammation score and the total lung injury score were also reduced in the study group (4.39 +/- 1.14 vs 2.61 +/- 1.09; 11.06 +/- 1.66 vs 6.94 +/- 1.43; p < 0.05, respectively). The concentrations of interleukin-6 and myeloperoxidase in bronchoalveolar lavage were significantly reduced in the study group (81.32 +/- 15.23 vs 53.55 +/- 15.48 pg/mL, 75.00 +/- 9.19 vs 50.00 +/- 7.37 u/mL; p < 0.05, respectively), whereas the interleukin-8 levels were similar between both groups (551.63 +/- 119.34 vs 563.68 +/- 137.14 pg/mL, p > 0.05).

CONCLUSIONS

Total liquid ventilation with FC-77 (3M, St. Paul, MN) reduces biochemical and histologic lung injury in piglets after cardiopulmonary bypass.

Cytokine response in children undergoing surgery for congenital heart disease

Pediatric cardiac surgery with cardiopulmonary bypass (CPB) induces a complex inflammatory response that may cause multiorgan dysfunction. The objective of this study was to measure postoperative cytokine production and correlate the magnitude of this response with intraoperative variables and postoperative outcomes. Serum samples from 20 children (median age, 15 months) undergoing cardiac surgery with CPB were obtained preoperatively and on postoperative days (POD) 1-3. Serum levels of interleukin (IL)-6, IL-8, and IL-10 increased significantly on POD 1 (p < 0.01) vs pre-op values to 271 +/- 68, 44 +/- 9, 7.5 +/- 0.8 pg/ml, respectively, whereas serum IL-1beta, IL-12, and tumor neurosis factor -alpha were not significantly changed. The serum IL-6 and IL-8 levels correlated positively (p < 0.01) with the degree of postoperative medical intervention as measured by the Therapeutic Interventional Scoring System and indicated a greater need for inotropic support (p = 0.057). A negative correlation (p < 0.01) between IL-6, IL-8, and mixed venous oxygen saturation suggested compromised cardiopulmonary function. Patients with single ventricle anatomy had the highest levels of IL-6 and IL-8 (629 +/- 131 and 70 +/- 17 pg/ml, respectively), with a mean CPB time of 106 +/- 23 minutes. Thus, the proinflammatory response after surgery with CPB was associated with postoperative morbidity with increased need for medical intervention.

The effects of propofol on lipid peroxidation and inflammatory response in elective coronary artery bypass grafting

OBJECTIVE

To determine whether the antioxidant and anti-inflammatory properties of propofol confer benefit in adult patients undergoing elective coronary artery bypass grafting.

DESIGN

Prospective, blinded, randomized, controlled clinical investigation.

SETTING

Single-center, university teaching hospital and academic research laboratory.

PARTICIPANTS

Twenty-one adult patients (11 control, 10 intervention) with chronic stable angina and normal ventricular function scheduled to undergo elective coronary artery bypass grafting.

INTERVENTIONS

All patients received a standardized fentanyl-isoflurane anesthetic. Fifteen minutes before reperfusion, patients in the intervention group received a target-controlled infusion of propofol, continued for 4 hours after cross-clamp release. Patients in the control group received saline administered in a similar fashion.

MEASUREMENTS

Serum concentration of malondialdehyde (MDA) (from systemic and coronary sinus blood); systemic concentrations of interleukins 4, 6, 8, and 10; and systemic leukocyte functions (respiratory burst, phagocytosis, and beta(2) integrin expression) were measured up to 36 hours after reperfusion.

RESULTS

A high serum malondialdehyde concentration was detected in the coronary sinus in control patients, 10 minutes after reperfusion; serum malondialdehyde was not detected in the coronary sinus at this time in patients who received propofol (41.4 [15.6-1,150] micromol/L v 0, p = 0.004). Interleukin-8 concentrations increased 2 and 4 hours after reperfusion in the control group. Interleukin-6 concentrations were greater in the control group than the propofol group 4 hours after clamp release (289.1 [165.2-561] rhog/mL v 153.2 (58.2-280.3) rhog/mL, respectively, p = 0.003). Mean dose of propofol was 31.7 mg/kg during the study period.

CONCLUSION

Clinically relevant concentrations of propofol may attenuate free radical-mediated and inflammatory components of myocardial reperfusion injury in patients undergoing elective coronary artery bypass graft surgery.

Side Effects of Cardiopulmonary Bypass:. What Is the Reality?

Despite many years of clinical and experimental research, the contribution of cardiopulmonary bypass (CPB) and cardioplegic arrest to morbidity and mortality following cardiac surgery remains unclear. This is due, in part, to lack of suitable control group against which bypass and cardioplegic arrest can be compared. The recent success of beating heart coronary artery bypass grafting has, however, for the first time, provided an opportunity to compare the same operation, in similar patient groups, with, or without CPB and cardioplegic arrest. CPB is associated with an acute phase reaction of protease cascades, leucocyte, and platelet activation that result in tissue injury. This is largely manifest as subclinical organ dysfunction that produces a clinical effect in those patients that generate an excessive inflammatory response or in those with limited functional reserve. The contribution of myocardial ischemia/reperfusion, secondary to aortic cross-clamping, and cardioplegic arrest, to the systemic inflammatory response and wider organ dysfunction is unknown, and requires further evaluation in clinical trials.

Differential-display polymerase chain reaction identifies nicotinamide adenine dinucleotide-ubiquinone oxidoreductase as an ischemia/reperfusion-regulated gene in cardiomyocytes

OBJECTIVE

Cardiac ischemia/reperfusion-induced oxidative damage often occurs in mitochondria. We identified differentially expressed genes in the canine heart after global cardiac ischemia/reperfusion injury was induced during cardiopulmonary bypass (CPB).

METHODS

Differential-display polymerase chain reaction (ddPCR) was performed on cardiac tissue from canine hearts with or without global cardiac ischemia/reperfusion injury induced during CPB. Ischemia/reperfusion-associated mitochondrial injury was investigated at the protein level using various cardioplegic solutions and Western blot analysis.

RESULTS

A mitochondrial protein nicotinamide adenine dinucleotide (NADH):ubiquinone oxidoreductase gene was identified on ddPCR. The NADH:ubiquinone oxidoreductase gene was up-regulated in canine hearts after 60 min of global cardiac ischemia/reperfusion injury during CPB. Western blot analysis revealed that, after manipulation with different cardioplegic solutions, increased Bcl-2 expression and decreased cytochrome c expression were associated with cardiomyocytic apoptosis.

CONCLUSIONS

The NADH:ubiquinone oxidoreductase gene is up-regulated during global cardiac ischemia/reperfusion injury during CPB in canines. To our knowledge, involvement of this gene in global cardiac ischemia/reperfusion injury during CPB has not been described previously. The NADH:ubiquinone oxidoreductase gene may have a role in the regulation of molecular changes during the global cardiac ischemia/reperfusion injury during CPB, such as the up-regulation of Bcl-2, which might block release of cytochrome c from the mitochondria and prevent cardiomyocytic apoptosis.

Glucocorticoids reduce cardiac dysfunction after cardiopulmonary bypass and circulatory arrest in neonatal piglets

OBJECTIVE

The hypotheses were that glucocorticoid administration could improve ventricular recovery by reducing cardiopulmonary bypass (CPB)-induced inflammatory response and that presurgical administration might be more effective than intraoperative dosing.

DESIGN

Animal case study.

SUBJECTS

Crossbred piglets (5-7 kg).

INTERVENTIONS

Piglets were cooled with CPB, followed by 120 mins of deep hypothermic circulatory arrest (DHCA). Animals were rewarmed to 38 degrees C, removed from CPB, and maintained for 120 mins. Methylprednisolone (60 mg/kg) was administered in the CPB pump prime (intraoperative glucocorticoid [intraop GC]) or 6 hrs before CPB (30 mg/kg) in addition to the intraoperative dose (30 mg/kg; pre- and intraop GC). Controls (no GC) received saline.

MEASUREMENTS AND MAIN RESULTS

In no GC, left ventricle (LV) positive change in pressure in time (+dP/dt) (mm Hg/sec) had a mean +/- SD of 1555 +/- 194 at baseline vs. 958 +/- 463 at 120 mins after CPB, p=.01). LV +dP/dt was maintained in glucocorticoid-treated animals (1262 +/- 229 at baseline vs. 1212 +/- 386 in intraop GC and 1471 +/- 118 vs. 1393 +/- 374 in pre-intraop GC). Glucocorticoids reduced myocardial interleukin-6 messenger RNA expression, measured by ribonuclease protection assay, at 120 mins after CPB compared with animals receiving saline (p<.05), although interleukin-6 plasma and LV protein concentrations were not affected. Interleukin-10 myocardial protein concentrations were elevated after CPB-DHCA with higher concentrations in glucocorticoid-treated animals (p<.05). Glucocorticoid treatment maintained myocardial concentrations of the inhibitor of nuclear factor-kappaB in the cytosol and decreased nuclear factor-kappaB concentrations detected in the nucleus in a DNA/protein interaction array.

CONCLUSIONS

Glucocorticoids improved recovery of LV systolic function in neonatal animals undergoing CPB-DHCA. Animals receiving glucocorticoids before CPB had better postoperative oxygen delivery than those receiving only intraoperative treatment. Maintenance of cardiac function after glucocorticoids might be due, in part, to alterations in the balance of pro- and anti-inflammatory proteins, possibly through nuclear factor-kappaB-dependent pathways.

Gene expression profile after cardiopulmonary bypass and cardioplegic arrest

OBJECTIVE

This study examines the cardiac and peripheral gene expression responses to cardiopulmonary bypass and cardioplegic arrest.

METHODS

Atrial myocardium and skeletal muscle were harvested from 16 patients who underwent coronary artery bypass grafting before and after cardiopulmonary bypass and cardioplegic arrest. Ten sample pairs were selected for patient similarity, and oligonucleotide microarray analyses of 12,625 genes were performed using matched precardiopulmonary bypass tissues as controls. Array results were validated with Northern blotting, real-time polymerase chain reaction, in situ hybridization, and immunoblotting. Statistical analyses were nonparametric.

RESULTS

Median durations of cardiopulmonary bypass and cardioplegic arrest were 74 and 60 minutes, respectively. Compared with precardiopulmonary bypass, postcardiopulmonary bypass myocardial tissues revealed 480 up-regulated and 626 down-regulated genes with a threshold P value of.025 or less (signal-to-noise ratio: 3.46); skeletal muscle tissues showed 560 and 348 such genes, respectively (signal-to-noise ratio: 3.04). Up-regulated genes in cardiac tissues included inflammatory and transcription activators FOS; jun B proto-oncogene; nuclear receptor subfamily 4, group A, member 3; MYC; transcription factor-8; endothelial leukocyte adhesion molecule-1; and cysteine-rich 61; apoptotic genes nuclear receptor subfamily 4, group A, member 1 and cyclin-dependent kinase inhibitor 1A; and stress genes dual-specificity phosphatase-1, dual-specificity phosphatase-5, and B-cell translocation gene 2. Up-regulated skeletal muscle genes included interleukin 6; interleukin 8; tumor necrosis factor receptor superfamily, member 11B; nuclear receptor subfamily 4, group A, member 3; transcription factor-8; interleukin 13; jun B proto-oncogene; interleukin 1B; glycoprotein Ib, platelet, alpha polypeptide; and Ras-associated protein RAB27A. Down-regulated genes included haptoglobin and numerous immunoglobulins in the heart, and factor H-related gene 2, protein phosphatase 1, regulatory subunit 3A, and growth differentiation factor-8 in skeletal muscle.

CONCLUSIONS

By establishing a profile of the gene-expression responses to cardiopulmonary bypass and cardioplegia, this study allows a better understanding of their effects and provides a framework for the evaluation of new cardiac surgical modalities directly at the genome level.

Combined steroid treatment for congenital heart surgery improves oxygen delivery and reduces postbypass inflammatory mediator expression

BACKGROUND

Steroid administration during cardiopulmonary bypass is thought to improve cardiopulmonary function by modulating bypass-related inflammation. This study was designed to compare preoperative and intraoperative methylprednisolone (MP) to intraoperative MP alone with respect to postbypass inflammation and clinical outcome.

METHODS AND RESULTS

Twenty-nine pediatric patients undergoing bypass procedures were randomly assigned to receive preoperative and intraoperative MP (30 mg/kg 4 hours before bypass and in bypass prime, n=14) or intraoperative MP only (30 mg/kg, n=15). Myocardial inflammatory mediator mRNA expression was determined in paired atrial biopsies (before and after bypass) by ribonuclease protection. Before and after bypass, serum IL-6 and IL-10 were measured by ELISA. Postoperative outcome was assessed by intubation time, CICU length of stay, fluid balance, arterio-venous O2 difference (DeltaA-VO2), and inotrope requirements. Compared with intraoperative MP alone, combined preoperative and intraoperative MP was associated with reduced myocardial mRNA expression for IL-6, MCP-1, and ICAM-1 both before and after bypass (P<0.05). Patients who received combined steroids had lower serum IL-6 and increased IL-10 at end-bypass (P<0.05), although differences were negligible by 24 hours. Combined MP treatment was associated with reduced fluid requirements, lower body temperature, and lower DeltaA-VO2 for the first 24 hours after surgery (P<0.05), along with trends toward improvement in other clinical outcomes.

CONCLUSIONS

Compared with intraoperative steroid treatment, combined preoperative and intraoperative steroid administration attenuates inflammatory mediator expression more effectively and is associated with improved indexes of O2 delivery in the first 24 hours after congenital heart surgery. These findings need to be confirmed in a larger multicenter trial.

Plasma cytokines do not reflect expression of pro- and anti-inflammatory cytokine mRNA at organ level after cardiopulmonary bypass in neonatal pigs

BACKGROUND

Plasma concentrations of inflammatory markers are increased in response to the trauma of cardiac surgery and cardiopulmonary bypass (CPB). It is, however, unknown whether the plasma cytokine levels and cytokine mRNA expression at organ level reflect each other.

METHODS

Twenty-six piglets (17-19 days) were allocated to the sham-group (sternotomy only, n = 13) or to the CPB-group (sternotomy, 120 min CPB procedure with 60-min aortic cross-clamp, n = 13). The pigs were observed for 0.5 h or 4 h post-CPB. Plasma levels of IL-1beta, IL-6, IL-8 and IL-10 and mRNA expression of TNF-alpha, IL-1beta, IL-6, IL-8, IL-10 and iNOS in organs were registered with concomitant changes in oxygenation index (OI) and expiratory nitric oxide (NO).

RESULTS

In pigs killed 0.5 h post-CPB there was a significant increase in IL-10 mRNA in the lungs and kidneys compared with the sham-group. IL-1beta mRNA was detectable in the kidneys and lungs of the CPB-pigs, while IL-6 mRNA was up regulated only in lungs. In pigs killed 4 h post-CPB a significantly higher IL-6 mRNA was found in heart tissue and a lower IL-10 mRNA was found in lungs of CPB pigs compared with the sham-group. There was a concomitant significant increase in OI and increased plasma IL-8 and IL-10 concentrations in the CPB-pigs compared with the sham-pigs.

CONCLUSION

The cytokine mRNA expression pattern was very different for the pigs killed already 0.5 h after the CPB procedure compared with the pigs killed 4 h post-CPB. The plasma cytokine levels poorly reflected mRNA expression of the pro- and anti-inflammatory cytokines.

Expression of FHL2 and cytokine messenger RNAs in human myocardium after cardiopulmonary bypass

BACKGROUND

Proinflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-6, and IL-8 have been implicated in myocardial injury following cardiopulmonary bypass (CPB). However, little evidence is currently available to directly confirm such a relationship. We have previously documented that a newly discovered 'four and a half LIM-only protein 2' (FHL2) is exclusively expressed in myofibres. We hypothesized that the upregulation of FHL2 is proportional to the degree of myocardial injury and investigated the myocardial expression of FHL2 together with these cytokine messenger RNAs (mRNAs) during clinical CPB.

METHODS

Intermittent hypothermic blood cardioplegia was used in all patients. Atrial myocardial biopsies were obtained immediately at the onset and at the end of CPB in 33 consecutive patients undergoing valvular or coronary artery surgery. TNF-alpha, IL-6, and IL-8 mRNA expressions in these myocardial samples were determined by semi-quantitative reverse transcription-polymerase chain reaction. Myocardial FHL2 expression was determined by Western blot analysis. Serum levels of the MB isoenzyme of creatine kinase (CK-MB) and cardiac troponin-I (cTnI) before surgery and 24 h after the end of CPB were also measured.

RESULTS

The duration of aortic crossclamping and CPB was 70+/-33 and 99+/-37 min, respectively. No elevated myocardial TNF-alpha mRNA expression was found after CPB. IL-6 mRNA expressions were detected in 14 pairs of the myocardial biopsies and were elevated in 11 (33%) post-CPB biopsies. Similarly, IL-8 mRNA expressions were detected in 19 pairs of samples and were elevated in 14 (42%) post-CPB biopsies. Among the 17 pairs of biopsies with positive FHL2 expression, FHL2 levels were increased in 11 (33%) post-CPB samples. Moreover, the elevated FHL2 expression was associated with an increase in IL-6 (P=0.018) and IL-8 (P=0.024) mRNA expression after CPB. Postoperative CK-MB and cTnI levels were significantly higher in patients with myocardial FHL2 expressions than those without (CK-MB, 13.5+/-2.3 vs. 6.5+/-0.8 ng/ml, P=0.022; cTnI, 10.7+/-2.0 vs. 3.5+/-0.6 ng/ml, P=0.0013).

CONCLUSIONS

Our findings demonstrate for the first time that both IL-6 and IL-8 mRNAs are upregulated in human cardiac myocytes following CPB and these cytokines may be involved in myocardial ischemia-reperfusion injury, as reflected by their association with an increased expression of FHL2.

Interleukin-8 secretion following cardiopulmonary bypass in children as a marker of early postoperative morbidity

BACKGROUND

Interleukin (IL)-8, an 8 kDa peptide, is the first chemoattractant identified as being specific for neutrophils. Its possible association with early postoperative morbidity following cardiopulmonary bypass (CPB) in infants and children is unknown. This prospective cohort study sought possible roles of IL-8 in the inflammatory response to CPB and investigated if changes in IL-8 levels and clinical course and outcome were related.

METHODS

IL-8 levels were measured in 16 children undergoing CPB. Systemic blood was collected after induction of anaesthesia (baseline), at 15 min after CPB onset and cessation, and at 1, 4, 8, 12 and 24 h thereafter.

RESULTS

Correlation coefficients between IL-8 levels and CPB time ranged from 0.45 to 0.55, heart rate 0.41--0.44, surgical time 0.41--0.63 and pH --0.56 to --0.50 (P < 0.05 for all parameters). Univariate analyses showed that patients requiring inotropic support and those with tachycardia had significantly higher postoperative IL-8 levels (P < 0.05). Furthermore, IL-8 levels were significantly higher in patients with surgical times > 200 min and in patients with an aortic clamp in place for > 65 min.

CONCLUSIONS

There was an association between IL-8 and early postoperative heart rate, and the need for inotropic support IL-8 correlated positively with surgical time, CPB time and heart rate and negatively with pH. IL-8 release may be related to some of the haemodynamic changes in the early postoperative course following CPB. The relationship between IL-8 and late markers of patient outcome in high-risk infants awaits further studies.

Myocardial immediate early gene activation after cardiopulmonary bypass with cardiac ischemia-reperfusion

BACKGROUND

The inflammatory process after cardiopulmonary bypass is accompanied by alterations in gene expression for various inflammatory mediators.

METHODS

To analyze differential gene expression after myocardial ischemia-reperfusion, subtraction hybridization was used to discover induction of TIS7/PC4, an immediate early gene heretofore not observed in the heart. This prompted characterization of the related immediate early genes c-fos and c-jun, by Northern analysis and in situ hybridization in human and lamb myocardium subjected to cardiopulmonary bypass with myocardial ischemia. For comparison, we analyzed expression of inducible nitric oxide synthase (iNOS), which requires cytokine-activation, resulting in a "delayed" response.

RESULTS

In ischemic-reperfused myocardium at endcardiopulmonary bypass, c-fos, c-jun, and TIS7/PC4 were induced, whereas iNOS transcripts were undetectable. Expression patterns of c-fos and c-jun by in situ hybridization were markedly different; myocardial c-fos expression was diffuse and homogeneous, whereas c-jun expression was patchy with areas of intense focal localization.

CONCLUSIONS

Cardiopulmonary bypass with myocardial ischemia rapidly induces the immediate early genes TIS7/PC4 (discovered by subtraction hybridization), and c-fos and c-jun (precursors to the transcriptional regulator AP-1). Immediate early genes presumably contribute to activation of inflammatory mediators after cardiopulmonary bypass and differences in their tissue expression patterns, as observed for c-fos and c-jun, presumably modulate their effect upon downstream gene activation.

Myositis in children with meningococcal disease: a role for tumour necrosis factor-alpha and interleukin-8?

OBJECTIVES

Myalgia is under-recognized in meningococcal disease (MCD). In septic shock, myositis is thought to be mediated by pro-inflammatory cytokines such as tumour necrosis factor-alpha (TNF-alpha), interleukin-8 (IL-8) and interleukin-6 (IL-6) but this has never previously been studied in MCD. We aimed to demonstrate whether muscle damage mediated via TNF-alpha and other pro-inflammatory cytokines occurs in MCD, as estimated by creatine kinase skeletal muscle isoenzyme (CK-MM) and cardiac isoenzyme (CK-MB) concentrations.

METHODS

A total of 68 children, median age 2.7 years, with a diagnosis of MCD were prospectively studied. Severity of disease was measured using the Glasgow Meningococcal Septicaemia Prognostic Score (GMSPS). Severe disease was defined as a GMSPS of > or =8. TNF-alpha, IL-8, IL-6 and IL-1Ra concentrations were determined on samples taken on admission.

RESULTS

CK-MM correlated significantly with TNF-alpha, IL-8 and GMSPS. There was no significant correlation between CK-MB and TNF-alpha or IL-6, but CK-MB correlated with GMSPS and IL-8. Fifty-six percent of children with MCD had evidence of muscle damage as manifested by elevated CK-MM.

CONCLUSIONS

TNF-alpha and IL-8 may be potential mediators in the pathophysiology of skeletal muscle damage in MCD.

Cellular and molecular aspects of myocardial dysfunction

Disruption of any one of a large number of balanced systems that maintain cardiomyocyte structure and function can cause myocardial dysfunction. Such disruption can occur either in response to acute stresses such as cardiac surgery with cardiopulmonary bypass and cross-clamping of the aorta or because of more chronic stresses resulting from factors such as genetic abnormalities, infection, or chronic ischemia. Several currently available therapies such as beta-adrenergic receptor agonists and antagonists, phosphodiesterase inhibitors, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and other agents affect cardiomyocytes in ways that are more far reaching than initially appreciated when these agents were first introduced into clinical practice. As our knowledge and understanding of myocardial dysfunction increases, particularly in the neonatal and pediatric patient, we will be able to further target interventions to highly specific perturbations of cellular function and individual genetic variability.

IL-8 concentration in coronary sinus blood during early coronary reperfusion after ischemic arrest

OBJECTIVE

Activation of the inflammatory response is an important factor contributing to complications of cardiopulmonary bypass. Increased level of proinflammatory cytokine - IL-8 has been reported during coronary artery bypass grafting (CABG) operations with the use of cardiopulmonary bypass. The aim of this study was to find out whether the heart is the main source of IL-8 during early coronary reperfusion.

METHODS

IL-8 concentration in coronary sinus before clamping and 5, 10, and 15 min after declamping of the aorta as well as in radial artery blood before clamping and 10 min after declamping of the aorta, was assessed in 30 patients undergoing CABG surgery.

RESULTS

We observed increase in IL-8 concentration in coronary sinus blood after declamping of the aorta, however no difference between coronary sinus and arterial blood concentration was noted. The median value of IL-8 concentration in coronary sinus blood was 1.85 pg/ml before ischemia and 15.4, 20.3, and 29.3 pg/ml in 5, 10 and 15 min after aortic declamping, respectively. Our additional finding was that there was a negative correlation between IL-8 level and hemoglobin saturation with oxygen in coronary sinus blood 10 min after coronary reperfusion.

CONCLUSIONS

We conclude that the heart is not the main source of IL-8 in early coronary reperfusion, although coronary reperfusion induces its release.

Sialyl lewis oligosaccharide preserves cardiopulmonary and endothelial function after hypothermic circulatory arrest in lambs

OBJECTIVE

Neutrophil adhesion to endothelium contributes to cardiopulmonary dysfunction after cardiac surgical procedures. Initial neutrophil-endothelial interactions involve selectins, which bind carbohydrate ligands, such as sialyl-Lewis(X). Blockade of selectin-mediated neutrophil interactions with CY1503, a synthetic oligosaccharide analog of sialyl-Lewis(X), could limit neutrophil-mediated injury after cardiopulmonary bypass.

METHODS

The efficacy of CY1503 treatment was tested in a lamb model of cardiopulmonary bypass with hypothermic circulatory arrest. Neonatal lambs received CY1503 (n = 6, CPB-CY1503) or saline solution vehicle (n = 7, CPB-saline) into the pump prime before bypass and as a continuous infusion throughout reperfusion. Five lambs served as control animals for in vitro microvessel studies. Indexes of myocardial function (preload recruitable stroke work index, and rate of pressure rise) and pulmonary function (compliance, airway resistance, and arterial PO (2)) were measured before bypass and during reperfusion. The effect of CY1503 on endothelium-dependent vascular reactivity was assessed by means of in vitro pulmonary and coronary microvessel studies.

RESULTS

Myocardial function was depressed after circulatory arrest, but CY1503 preserved function near baseline (36% +/- 25% vs 99% +/- 19% of baseline at 3 hours of reperfusion). CY1503-treated animals also demonstrated improved pulmonary function during reperfusion. In vitro microvessel analysis of vascular reactivity revealed endothelial dysfunction after circulatory arrest compared with control lambs. CY1503-treated lambs (CPB-CY1503) had intact endothelial function, as demonstrated by normal vasodilatory responses to endothelium-dependent vasodilators.

CONCLUSIONS

CY1503 preserves cardiopulmonary and endothelial function after cardiopulmonary bypass and hypothermic circulatory arrest in neonatal lambs. This suggests a role for selectin-mediated, neutrophil-endothelial interactions in the inflammatory response after cardiac operations.

Leukocyte-depleted continuous blood cardioplegia for coronary artery bypass grafting

Many cardiac surgeries are performed with blood cardioplegia. However, some studies suggest that activated neutrophils form blood cardioplegia can cause reperfusion injury. In this study we assessed myocardial protection using a leukocyte-depleted cardioplegic solution. Patients undergoing elective coronary artery bypass grafting (CABG) with continuous blood cardioplegia were divided into two groups: the LD group, which received leukocyte-depleted blood cardioplegia (n = 11); and the control group, which received nonfiltered blood cardioplegia (n = 11). IL-6, IL-8, CK-MB, and troponin T were measured in the coronary sinus blood immediately after the release of the aortic cross-clamp. Cytokine concentrations were also measured upon the patient's return to the ICU. The total dopamine and dobutamine doses, hemodynamic measurements after surgery, and the leukocyte filtration rate were also measured. During antegrade cardioplegia infusion, leukocytes were almost completely removed (filtration rate: 85.8+/-4.0%). However, during terminal warm cardioplegia, leukocyte removal decreased (filtration rate: 39.9+/-7.8%). Immediately after the release of the aortic cross-clamp, plasma CK-MB and troponin T concentrations were significantly lower in the LD group (17.7+/-1.9 U/l and 0.017+/-0.002 ng/ml, respectively) than in the control group (30.3+/-3.6 U/l and 0.072+/-0.029 ng/ml, respectively). The IL-6 and IL-8 concentrations were similar in the LD group and the control group. After the return to the ICU, the CK-MB and troponin T concentrations were similar in the two groups. No significant differences were found in the total doses of dopamine or dobutamine after surgery in the two groups (99+/-77 vs 101+/-128 microg/kg/min). No significant differences were found in the hemodynamic parameters after surgery in the two groups. In patients undergoing CABG with continuous blood cardioplegia, leukocyte-depleted blood cardioplegic solution may attenuate reperfusion injury.

Effect of ultrafiltration during cardiopulmonary bypass for pediatric cardiac surgery

The effect of ultrafiltration during cardiopulmonary bypass (CPB) was evaluated for correcting ventricular septal defects with associated pulmonary hypertension in patients less than 18 months old. Interleukin (IL)-6 and IL-8 concentrations in the blood, ultrafiltrate, and urine were measured. The blood IL-6 concentration increased to 128.4+/-20.2 pg/ml by the end of surgery, which is lower than the concentration seen in adult patients (273.1+/-48.2 pg/ml, p < 0.02). The blood IL-8 concentration was not significantly different than that of adults. The total amounts of excreted IL-6 in the ultrafiltrate and urine during CPB were 11.5+/-0.32 pg/kg and 0.32+/-0.07 pg/kg, respectively (p < 0.05). The total amounts of excreted IL-8 in the ultrafiltrate and urine were 4.64+/-0.69 pg/kg and 1.92+/-0.56 pg/kg, respectively (p < 0.05). No differences were seen in these values for excretion between children and adults. We conclude that ultrafiltration during CPB in pediatric patients is more effective in removing proinflammatory cytokines than in adults and more effective than renal filtration alone.

Interleukin-8 mRNA expression in circulating leucocytes during cardiopulmonary bypass

Interleukin-8 (IL-8) is found in patients following cardiopulmonary bypass (CPB). It may contribute to microvascular injury by activating neutrophils. We examined IL-8 mRNA expression in leucocytes in bypass. IL-8 mRNA levels were measured by Northern analysis and densitometry of isolated mononuclear leucocytes and neutrophils from blood samples taken before, during, and 2 and 48 h after CPB. Plasma IL-8 was measured at each time-point by immunoassay. A strong signal for IL-8 mRNA was detected in neutrophils in five of five and, more weakly, in mononuclear leucocytes of three of five patients studied. The signal peaked consistently during, and fell following bypass, usually to undetectable levels by 48 h. There was always a detectable signal in neutrophils preoperatively. Plasma IL-8 increased from undetectable prebypass levels and peaked later (2 h postbypass) in four of five patients. In the other patient, the cytokine remained detectable throughout. These data demonstrate that IL-8 transcription occurs in leucocytes before and during CPB, but suggest that much of the IL-8 detectable in plasma following bypass may derive, not from these leucocytes, but from other cell types. The release of some IL-8 by neutrophils could lead to local positive feedback in neutrophil recruitment and associated endothelial injury.

Inhibition of interleukin-8 blocks myocardial ischemia-reperfusion injury

INTRODUCTION

Interleukin-8 is thought to play a role in neutrophil activation and transcapillary migration into the interstitium. Because neutrophils are principal effector cells in acute myocardial ischemia-reperfusion injury, we postulated that the inhibition of interleukin-8 activity with a neutralizing monoclonal antibody directed against rabbit interleukin-8 (ARIL8.2) would attenuate the degree of myocardial injury encountered during reperfusion.

METHODS

In New Zealand White rabbits, the large branch of the marginal coronary artery supplying most of the left ventricle was occluded for 45 minutes, followed by 2 hours of reperfusion. Fifteen minutes before reperfusion, animals were given an intravenous bolus of either 2 mg/kg of ARIL8.2 or 2 mg/kg anti-glycoprotein-120, an isotype control antibody that does not recognize interleukin-8. At the completion of the 120-minute reperfusion period, infarct size was determined.

RESULTS

In the area at risk for infarction, 44.3% +/- 4% of the myocardium was infarcted in the anti-glycoprotein-120 group compared with 24.8% +/- 9% in the ARIL8.2 group (p < 0.005). In control animals, edema and diffuse infiltration of neutrophils were observed predominantly in the infarct zone and the surrounding area at risk. Tissue myeloperoxidase determinations did not differ significantly between groups, indicating that the cardioprotective effect of ARIL8.2 was independent of an effect on neutrophil infiltration.

CONCLUSIONS

A specific monoclonal antibody that neutralizes interleukin-8 significantly reduces the degree of necrosis in a rabbit model of myocardial ischemia-reperfusion injury.

Interindividual variations in cytokine levels following cardiopulmonary bypass

Cardiopulmonary bypass (CPB) is associated with an inflammatory response, mainly caused by the trauma of surgery, contact of blood with the artificial surface of the circuit, and reperfusion injury, resulting in increased capillary permeability, respiratory distress, low cardiac output, and multiorgan failure. The inflammatory reaction includes an activation of the humoral and cellular immune system with enhanced release of cytokines. The present study focused on the effect of CPB on the time course of pro- and anti-inflammatory cytokines. In 20 patients undergoing coronary artery bypass grafting, the plasma concentration of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-2, IL-4, IL-6, IL-8, and IL-10 was investigated pre-, intra-, and postoperatively by enzyme-linked immunosorbent assay technique. With the exception of IFN-gamma, all the other cytokines could be detected in the patients plasma. However, neither TNF-alpha nor IL-1 beta and IL-2 revealed significant changes in concentration during the investigated time period. In contrast, IL-6 and IL-8 levels peaked early postoperatively, reaching median concentrations of 430 pg/ml (221 pg per ml/558 pg per ml; lower/upper quartiles, respectively) and approximately 12 pg/ml (0/17 pg/ml; lower/upper quartiles, respectively). IL-4 and IL-10, respectively, revealed maximal concentrations of approximately 2 pg/ml (0/39 pg/ml; lower/upper quartiles, respectively) and 208 pg/ml (76 pg per ml/380 pg per ml; lower/upper quartiles, respectively) immediately after protamine administration, preceding the maximal concentration of IL-6. The degree of the observed modulation of cytokine patterns during and after CPB seemed to be patient-dependent, since large interindividual variations in cytokine levels were observed, not only preoperatively, but especially during and following CPB. However, IL-6 and IL-10 showed the least interindividual variations, suggesting that these cytokines may give reliable information regarding modulation of the immune response following CPB and its consequences for the patient's outcome.

Cytokine responses to cardiopulmonary bypass: lessons learned from cardiac transplantation

BACKGROUND

A growing body of evidence relates the release during cardiopulmonary bypass (CPB) of proinflammatory cytokines, such as tumor necrosis factor-alpha, interleukin (IL)-6, and IL-8, to the postoperative systemic inflammatory response syndrome. Antiinflammatory cytokines, such as IL-10, however, may also play an important role in limiting these complications.

METHODS

The English-language literature was reviewed. Emphasis was placed on cytokine responses during clinical CPB for cardiac operations and, in particular, for heart and heart-lung transplantation.

RESULTS

The recent data indicate that (1) although cytokine release can be triggered by many factors during CPB, ischemia-reperfusion may play the most important role; (2) the levels of tumor necrosis factor-alpha, IL-6, and IL-8 are correlated with the duration of cardiac ischemia and the myocardium is a major source of these three cytokines during CPB; (3) IL-10 levels are correlated with the duration of CPB and the liver is a major source of IL-10 during CPB; and (4) steroid pretreatment is an effective intervention to inhibit the release of proinflammatory cytokines and enhance IL-10 production.

CONCLUSIONS

The improved knowledge of cytokine responses to CPB may help to develop interventions aimed at reducing postoperative morbidity and mortality.