Cytokine Responses in Low-Risk Coronary Artery Bypass Surgery

Effects of intravenous inflammasome inhibitor (NuSepin) on suppression of proinflammatory cytokines release induced by cardiopulmonary bypass in swine model: a pilot study

The systemic inflammatory response syndrome can occur due to an inflammatory reaction to the release of cytokines, and it has been linked to the circulation of pro- and anti-inflammatory cytokines. The cardiopulmonary bypass (CPB) system is known to activate numerous inflammatory pathways. Applying CPB in large animals for an extended period may be useful as a controlled experimental model for systemic inflammatory responses. The authors hypothesized that 0.2 mg/kg NuSepin® would inhibit CBP-induced proinflammatory cytokine release, and attenuate CPB-induced vasoplegia. CPB was maintained for 2 h in 8 male Yorkshire pigs. Ten ml of saline was administered intravenously to the control group, while the study group received 10 ml of NuSepin® (0.2 mg/kg), before start of CPB. Blood samples were collected at four different time points to evaluating the level of cytokine (TNF-α, IL-1β, IL-6, IL-8) release during and after CBP. All vital signals were recorded as continuous waveforms using the vital recorder®. Our study demonstrated that IL-6 increased in both groups during CPB remained unchanged. However, in the Nusepin group, IL-6 levels rapidly decreased when CPB was stopped and the proinflammatory reaction subsided. Furthermore, the dose of norepinephrine required to maintain a mean pressure of 60 mmHg was also lower in the Nusepin group.

Monocyte Metabolism and Function in Patients Undergoing Cardiac Surgery

Objective

Cardiopulmonary bypass (CPB) can lead to systemic inflammation, which is associated with higher morbidity. Therefore, we investigated the metabolism of isolated blood monocytes before and after CPB compared to healthy controls.

Methods

In this prospective, monocentric, observational study, we included 30 patients undergoing CPB and 20 controls. We isolated monocytes from heparinized blood and investigated their metabolism by using Seahorse technology before (t0), 4 h (t4), and 24 h (t24) after the start of the CPB. We also examined programmed cell death 1 ligand (PD-L1), PD-L2, V-domain Ig suppressor of T cell activation (VISTA), and human leukocyte antigen-DR isotype (HLA-DR) using fluorescence-activated cell sorting analysis. Additionally, we investigated plasma cytokine levels in patients without and after ex vivo stimulation.

Results

CPB-induced inflammatory responses are shown by significantly elevated plasma interleukin-6 levels in the CPB group compared to baseline and controls [t0: 0 ng/ml (95%CI 0-0 ng/ml); t4: 0.16 ng/ml (95%CI 0.1-0.197 ng/ml), p < 0.0001; t24: 0.11 ng/ml (95% CI 0.1-0.16 ng/ml), p < 0.0001, and controls: 0 ng/ml (95% CI 0-0 ng/ml)]. The cytokine release in the ex vivo stimulation is reduced for lipopolysaccharide stimulation at t4 [t0: 35.68 ng/ml (95% CI 22.17-46.57 ng/ml) vs. t4: 15.02 (95% CI 10.25-24.78 ng/ml), p < 0.0001]. Intracellular metabolism of monocytes after CPB showed a protracted shift to aerobic glycolysis [t0: 179.2 pmol/min (95% CI 138.0-205.1 pmol/min) vs. t24: 250.1 pmol/min (95% CI 94.8-300.2 pmol/min), p < 0.0001]. Additionally, we observed an altered metabolism in monocytes in patients undergoing cardiac surgery compared to controls even before any surgical procedure [t0: 179.2 pmol/min (95% CI 138.0-205.1) vs. controls 97.4 (95% CI 59.13-144.6 pmol/min), p = 0.0031].

Conclusion

After CPB, patients' monocytes show a shift in metabolism from oxidative phosphorylation to aerobic glycolysis, which is associated with energy-demanding and proinflammatory processes. This is the first study to show changes in monocyte immunometabolism in cardiac surgery. Monocytes of patients undergoing cardiac surgery were leaning toward aerobic glycolysis even before any surgical procedure was conducted. Leaving the question of the pathophysiological mechanisms for future studies to be investigated and paving the way for potential therapy approaches preventing inflammatory effects of CPB.

Pathophysiology of Cardiopulmonary Bypass

The techniques and equipment of cardiopulmonary bypass (CPB) have evolved over the past 60 years, and numerous numbers of cardiac surgical procedures are conducted around the world using CPB. Despite more widespread applications of percutaneous coronary and valvular interventions, the need for cardiac surgery using CPB remains the standard approach for certain cardiac pathologies because some patients are ineligible for percutaneous procedures, or such procedures are unsuccessful in some. The ageing patient population for cardiac surgery poses a number of clinical challenges, including anemia, decreased cardiopulmonary reserve, chronic antithrombotic therapy, neurocognitive dysfunction, and renal insufficiency. The use of CPB is associated with inductions of systemic inflammatory responses involving both cellular and humoral interactions. Inflammatory pathways are complex and redundant, and thus, the reactions can be profoundly amplified to produce a multiorgan dysfunction that can manifest as capillary leak syndrome, coagulopathy, respiratory failure, myocardial dysfunction, renal insufficiency, and neurocognitive decline. In this review, pathophysiological aspects of CPB are considered from a practical point of view, and preventive strategies for hemodilutional anemia, coagulopathy, inflammation, metabolic derangement, and neurocognitive and renal dysfunction are discussed.

The effect of RBC transfusions on cytokine gene expression after cardiac surgery in patients developing post-operative multiple organ failure

AIM

To determine the effect of red blood cell (RBC) transfusions during cardiac surgery on cytokine gene expression (GE) in relation to multiple organ failure (MOF) development after systemic inflammatory response syndrome (SIRS).

BACKGROUND

RBC transfusion in cardiac surgery patients is dose-dependently associated with post-operative MOF, possibly acting as a second hit after cardiopulmonary bypass.

METHODS

For this observational study, 29 patients divided into four groups of cardiac surgery patients were selected from a randomised controlled trial (RCT). Group 1: no-RBC, no-MOF (N = 8); group 2: MOF, no-RBC (N = 7); group 3: RBC, no-MOF (N = 6); group 4: RBC and MOF (N = 8). Selection was based on age, gender, number of (leukocyte-depleted) RBC transfusions, type and duration of surgery. A 114 cytokine GE array was applied to blood samples withdrawn before and 24 h after surgery. Expression of selected genes was confirmed with reverse transcriptase real time-polymerase chain reaction (RT-PCR).

RESULTS

Nineteen of the 39 detectable genes showed a significant change in GE after surgery. Confirmed by RT-PCR, transfused MOF patients exhibit significantly less downregulation of CD40 ligand than control patients. Patients who would develop MOF show significantly larger increases in GE of transforming growth factor-α (TGF-α), tumour necrosis factor (TNF)-superfamily members 10 and 13B (TNFsf10/13B).

CONCLUSIONS

When tested at 24 h after surgery, cytokine GE in peripheral blood leucocytes showed no significant differences between those transfused and those not transfused. Some alterations were seen in those developing MOF compared to those who did not, but the findings offer no role of leukocyte depleted (LD) RBC transfusion in the development of MOF.

Soluble adhesion molecules in coronary artery bypass surgery

Plasma levels of sE-selectin, sP-selectin, and sICAM-1 were measured before anesthesia and at 0.5, 4, and 20 hours after cardiopulmonary bypass in 37 men undergoing coronary artery bypass surgery. Plasma sE-selectin remained close to the preoperative levels. The levels of sP-selectin increased significantly from 46.5 +/- 15.3 ng x mL(-1) to 69.3 +/- 39.6 ng x mL(-1) at 0.5 hours, 84.1 +/- 45.5 ng x mL(-1) at 4 hours, and 79.6 +/- 35.5 ng x mL(-1) at 20 hours. Plasma sICAM-1 levels decreased 0.5 hours after cardiopulmonary bypass, recovered at 4 hours, and showed a significant increase at 20 hours. The changes in plasma levels of adhesion molecules did not correlate with the duration of bypass or aortic crossclamping, hemodynamics, or creatine kinase-MB levels. However, sE-selectin and sICAM-1 levels increased considerably more in patients who needed norepinephrine in the intensive care unit. These results indicate that the transient changes in plasma levels of soluble adhesion molecules are not associated with postoperative myocardial injury in low-risk coronary grafting, although they correlate with the need for a vasopressor.

Imbalance of pro- and anti-inflammatory cytokine responses in elderly patients after coronary artery bypass grafting

BACKGROUND AND AIMS

Increased inflammatory activity has been observed in elderly people. The aim of this study was to determine whether cytokine responses after coronary artery bypass grafting (CABG) in elderly patients are different from those in younger patients.

METHODS

Fifty-five male patients admitted for first-time elective coronary artery bypass surgery were divided into two age groups: group I, patients younger than 70 years (N=40); and group II, patients aged 70 years or older (N=15). Perioperative levels of cytokines and CK-MB were measured. Hemodynamic data were recorded.

RESULTS

Marginally higher IL-6 (p=0.048) and IL-8 (p=0.041) levels were observed during the intensive care unit (ICU) stay in the elderly as compared with younger patients. Lower IL-10 levels were detected in the elderly 5 minutes after reperfusion to the myocardium (p<0.05). Although the postoperative hemodynamic change was similar in both groups, the elderly needed vasopressor treatment more often during the ICU stay. This was associated with lower IL-10 levels 5 minutes after reperfusion.

CONCLUSIONS

The present results show the age-related imbalance of pro- and anti-inflammatory responses after CABG, associated with hemodynamic instability in the elderly.

Soluble adhesion molecules in coronary surgery and cardiopulmonary bypass with pump prime aprotinin

OBJECTIVE

The purpose of the present study was to establish whether pump prime aprotinin could influence soluble adhesion molecules in patients undergoing elective coronary artery bypass surgery.

DESIGN

Thirty patients admitted for first-time elective coronary artery bypass surgery were randomized into control or aprotinin groups. Patients in the aprotinin group received 280 mg of aprotinin in the pump prime. Plasma levels of soluble adhesion molecules were analyzed perioperatively.

RESULTS

There were no significant changes in plasma sE-selectin after the operation in either group. Plasma sP-selectin increased significantly up to 20 h after reperfusion to the myocardium. Plasma sICAM-1 decreased in the early stage after cardiopulmonary bypass (CPB), then recovered at 4 h after reperfusion and a significant increase in sICAM-1 was observed 20 h later. There were no significant differences between the groups in postoperative changes in sP-selectin (p = 0.21) and sICAM-1 (p = 0.91).

CONCLUSION

Pump prime aprotinin did not influence plasma levels of E-selectin, P-selectin and ICAM-1 in the present patients. The present results do not support the concept of an anti-inflammatory effect of pump prime aprotinin.

Cardioprotective effect of adenosine pretreatment in coronary artery bypass grafting

OBJECTIVE

There are several reports of the use of adenosine as a cardioprotective agent during cardiac surgery. Adenosine treatment might affect neutrophils and inflammatory mediators. The present prospective randomized study was designed to investigate the effect of adenosine pretreatment on myocardial recovery and inflammatory response in patients undergoing elective coronary artery bypass surgery.

DESIGN

A prospective, randomized, controlled study.

SETTING

Operative unit and ICU in a university hospital in Finland.

PATIENTS

Thirty male patients undergoing primary, elective coronary revascularization.

INTERVENTIONS

Patients in the adenosine group received a 7-min infusion of adenosine (total, 650 microg/kg) before the initiation of cardiopulmonary bypass.

MEASUREMENTS

Postoperative creatine kinase (CK)-MB release and hemodynamics were recorded. Perioperative leukocyte and cytokine release were measured.

RESULTS

Adenosine pretreatment resulted in less CK-MB release and an improved postbypass cardiac index. Similar leukocyte counts and cytokine responses were seen in both groups perioperatively. Neutrophil counts were similar between the groups before and after myocardial ischemia when measured simultaneously in arterial and coronary sinus blood.

CONCLUSIONS

The present results support the hypothesis that adenosine pretreatment is cardioprotective in humans, but the present dose failed to regulate the inflammatory responses after coronary artery bypass grafting.

Inflammatory cytokines and soluble receptors after coronary artery bypass grafting

Much interest has been focused on the overexpression of proinflammatory cytokines, but studies on their soluble receptors are rare. For a comprehensive picture of cytokine activation in cardiac surgery, a combination of cytokines and the corresponding soluble receptor concentration should be determined. Blood samples were collected from the radial artery and coronary sinus perioperatively in ten patients undergoing coronary artery bypass grafting with cardiopulmonary bypass. TNF-alpha, IL-6, sTNFRI, sTNFRII, and sIL-6R levels in the plasma were determined. Systemic TNFRI, TNFRII and IL-6 increased significantly after reperfusion to the myocardium, while perioperative systemic sIL-6r levels were similar. Arterial and sinus levels of TNFRI, TNFRII and sIL-6r were similar before cardiopulmonary bypass. Five minutes after reperfusion to the myocardium, higher sinus TNFRI and TNFRII and lower sinus sIL-6R levels were observed as compared to the arterial levels. The myocardium release of sTNFRI (r=0.57, P=0.089) and sTNFRII (r=0.64, P=0.047) positively correlated with the change of cardiac index after cardiopulmonary bypass. Myocardium releases sTNFRI and sTNFRII after ischaemic-reperfusion injury, and this may be of benefit to cardiac performance. sIL-6R is constantly being produced in areas other than the myocardium, while sIL-6R levels are reduced by consumption in the myocardium after ischaemic-reperfusion injury.