Monitoring of monocyte functional state after extracorporeal circulation: a flow cytometry study

Effects of extracorporeal circulation with different time on platelet count after cardiac surgery: a retrospective study based on medical records

Our objective was to observe the effects of extracorporeal circulation (ECC) with different time on platelet count in patients undergoing cardiac surgery. A total of 427 patients who underwent elective cardiac surgery under ECC in affiliated hospital of north Sichuan medical college from January 1, 2018 to July 31, 2021 were divided into three groups according to ECC time. We concluded that thrombocytopenia was common after ECC, maximum drop of the platelet counts after ECC was usually seen on the second day after ECC, and platelet counts started to recover on the fifth day after ECC. With the extension of ECC time, the drop in platelet counts is more pronounced, the volume of perioperative blood loss and blood products transfusion are more, and the recovery level and speed of platelet counts is lower.

Inflammation and Oxidative Stress in the Context of Extracorporeal Cardiac and Pulmonary Support

Extracorporeal circulation (ECC) systems, including cardiopulmonary bypass, and extracorporeal membrane oxygenation have been an irreplaceable part of the cardiothoracic surgeries, and treatment of critically ill patients with respiratory and/or cardiac failure for more than half a century. During the recent decades, the concept of extracorporeal circulation has been extended to isolated machine perfusion of the donor organ including thoracic organs (ex-situ organ perfusion, ESOP) as a method for dynamic, semi-physiologic preservation, and potential improvement of the donor organs. The extracorporeal life support systems (ECLS) have been lifesaving and facilitating complex cardiothoracic surgeries, and the ESOP technology has the potential to increase the number of the transplantable donor organs, and to improve the outcomes of transplantation. However, these artificial circulation systems in general have been associated with activation of the inflammatory and oxidative stress responses in patients and/or in the exposed tissues and organs. The activation of these responses can negatively affect patient outcomes in ECLS, and may as well jeopardize the reliability of the organ viability assessment, and the outcomes of thoracic organ preservation and transplantation in ESOP. Both ECLS and ESOP consist of artificial circuit materials and components, which play a key role in the induction of these responses. However, while ECLS can lead to systemic inflammatory and oxidative stress responses negatively affecting various organs/systems of the body, in ESOP, the absence of the organs that play an important role in oxidant scavenging/antioxidative replenishment of the body, such as liver, may make the perfused organ more susceptible to inflammation and oxidative stress during extracorporeal circulation. In the present manuscript, we will review the activation of the inflammatory and oxidative stress responses during ECLP and ESOP, mechanisms involved, clinical implications, and the interventions for attenuating these responses in ECC.

Ex vivo immune profiling in patient blood enables quantification of innate immune effector functions

The assessment of a patient's immune function is critical in many clinical situations. In complex clinical immune dysfunction like sepsis, which results from a loss of immune homeostasis due to microbial infection, a plethora of pro- and anti-inflammatory stimuli may occur consecutively or simultaneously. Thus, any immunomodulatory therapy would require in-depth knowledge of an individual patient's immune status at a given time. Whereas lab-based immune profiling often relies solely on quantification of cell numbers, we used an ex vivo whole-blood infection model in combination with biomathematical modeling to quantify functional parameters of innate immune cells in blood from patients undergoing cardiac surgery. These patients experience a well-characterized inflammatory insult, which results in mitigation of the pathogen-specific response patterns towards Staphylococcus aureus and Candida albicans that are characteristic of healthy people and our patients at baseline. This not only interferes with the elimination of these pathogens from blood, but also selectively augments the escape of C. albicans from phagocytosis. In summary, our model could serve as a valuable functional immune assay for recording and evaluating innate responses to infection.

Blood Monocyte Phenotype Fingerprint of Stable Coronary Artery Disease: A Cross-Sectional Substudy of SMARTool Clinical Trial

Background and Aims

Atherosclerosis is an inflammatory disease with long-lasting activation of innate immunity and monocytes are the main blood cellular effectors. We aimed to investigate monocyte phenotype (subset fraction and marker expression) at different stages of coronary atherosclerosis in stable coronary artery disease (CAD) patients.

Methods

73 patients with chronic coronary syndrome were evaluated by CT coronary angiography (CTCA) and classified by maximal diameter stenosis of major vessels into three groups of CAD severity: CAD1 (no CAD/minimal CAD, n° = 30), CAD2 (non-obstructive CAD, n° = 21), and CAD3 (obstructive CAD, n° = 22). Flow cytometry for CD14, CD16, and CCR2 was used to quantify Mon1, Mon2, and Mon3 subsets. Expression of CD14, CD16, CD18, CD11b, HLA-DR, CD163, CCR2, CCR5, CX3CR1, and CXCR4 was also measured. Adhesion molecules and cytokines were quantified by ELISA.

Results

Total cell count and fraction of Mon2 were higher in CAD2 and CAD3 compared to CAD1. By multivariate regression analysis, Mon2 cell fraction and Mon2 expression of CX3CR1, CD18, and CD16 showed a statistically significant and independent increase, parallel to stenosis severity, from CAD1 to CAD2 and CAD3 groups. A similar trend was also present for CX3CR1 and HLA-DR expressions on total monocyte population. A less calcified plaque composition was associated to a higher Mon2 expression of CD16 and higher TNF-α levels. IL-10 levels were lower at greater stenosis severity, while the IFN-γ/IL-10 ratio, a marker of a systemic pro-inflammatory imbalance, was directly correlated to stenosis degree and number of noncalcified plaques.

Conclusions

The results of this study suggest that a specific pattern of inflammation-correlated monocyte marker expression is associated to higher stenosis severity and less calcified lesions in stable CAD. The clinical trial Identifier is NCT04448691.

Differential modulatory effects of Propofol and Sevoflurane anesthesia on blood monocyte HLA-DR and CD163 expression during and after cardiac surgery with cardiopulmonary bypass: a preliminary randomized flow cytometry study

INTRODUCTION

The increase of the anti-inflammatory CD163^highHLA-DR^low blood monocyte subset is one of the mechanisms dampening inflammation during cardiac surgery with cardiopulmonary bypass. We evaluated the effect of two different anesthetic protocols, intravenous Propofol infusion or Sevoflurane-gas administration, on the perioperative frequency of this subset.

METHODS

Blood from patients (Propofol = 11, Sevoflurane = 13) undergoing minimally invasive mitral valve surgery was drawn preoperatively (T1), before declamping (T2), at 6 (T3), 24 (T4), 48 (T5), and 72 hours (T6) after declamping. C-reactive protein, haptoglobin, and lactate dehydrogenase were measured. A hemolytic index, as C-reactive protein/haptoglobin ratio, was introduced. Monocyte expression of HLA-DR, CD163, and the CD163^highHLA-DR^low subset fraction was quantified by flow cytometry. Baseline-referred variations of plasmatic and cellular data at T2 were normalized for clamping times. Subsequent time-point variations were normalized for the final cardiopulmonary bypass times.

RESULTS

Variations of hemolytic index and lactate dehydrogenase were higher with Propofol at T3 (p = 0.004 and p = 0.02, respectively) when compared with Sevoflurane. At T2, the down-modulation of CD163 was higher with Propofol (p = 0.005). Starting from T3, the up-regulatory trend of CD163 was basically higher with Propofol, although not significantly. Propofol induced higher increments of HLA-DR low fractions, at T2 (p = 0.04) and, to a lesser extent, at T4 (p = 0.06). Starting from T3, the CD163^highHLA-DR^low subset variations were higher with Propofol, especially at T4 and T6.

CONCLUSION

Propofol seems to induce a higher postoperative fraction of the CD163^highHLA-DR^low monocyte subset. This could represent either a compensatory mechanism dampening the higher inflammatory condition observed with Propofol at T2 or a consequence of a higher postoperative Propofol-induced hemolysis.

High postoperative monocyte indicates inferior Clinicopathological characteristics and worse prognosis in lung adenocarcinoma or squamous cell carcinoma after lobectomy

BACKGROUND

Peripheral monocyte count is an assessable parameter. Recently, evidence suggested an elevated preoperative monocyte counts predicting poor prognosis in malignancies. The aim of this study was to determine the prognostic effect of early postoperative blood monocyte count in patients with lung adenocarcinoma or squamous cell carcinoma following lobectomy.

METHODS

We retrospectively reviewed patients with operated lung adenocarcinoma or squamous cell carcinoma from 2006 to 2011 in Western China Lung Cancer database. Univariate analysis on disease-free survival (DFS) and overall survival (OS) was performed using the Kaplan-Meier and log-rank tests, and multivariate analysis was conducted using the Cox proportional hazards regression model.

RESULTS

There were 433 patients enrolled in our analysis. High postoperative elevated monocyte was associated with male gender (P < 0.001), positive smoking history (P = 0.005), and higher N stage (P = 0.002) and higher tumor stage (P = 0.026). Two-tailed log-rank test indicated patients with an early postoperative elevated monocyte count predicted a poor DFS and OS overall (P < 0.001, P < 0.001, respectively) as well as in subgroup analysis, and further presented as a promising independent prognostic factor for both DFS and OS (HR = 2.991, 95%CI: 2.243-3.988, P < 0.001; HR = 2.705, 95%CI: 1.977-3.700, P < 0.001, respectively) on multivariate analysis. However, no significance was detected for preoperative monocyte in multivariate analysis.

CONCLUSIONS

Elevated early postoperative peripheral monocyte count was an independent prognostic factor of poor prognosis and inferior clinicopathological features for patients with operable lung adenocarcinoma or squamous cell carcinoma by lobectomy.

A Thrombomodulin Gene Polymorphism (C1418T) Is Associated with Early Outcomes in Patients Undergoing Coronary Artery Bypass Graft Surgery with a Conventional Cardiopulmonary Bypass during Hospitalization

Background: Thrombomodulin (TM) is a type of cell membrane-bound anticoagulant protein cofactor in the thrombin-mediated activation of protein C. Previous evidence has shown an association between TM polymorphisms and systemic inflammation. Conventional cardiopulmonary bypass (CPB), beating-heart CPB, and off-pump techniques have been widely used in cardiac surgery. However, these techniques may also cause systemic inflammatory responses in the patients. Whether TM polymorphisms are associated with systemic inflammation after cardiac surgery is still unclear. Methods: We analyzed the TM gene C1418T polymorphisms in 347 patients who underwent coronary artery bridge graft (CABG) surgery using allele-specific primers in a PCR assay. The clinical data during the hospital stay were collected and tested for correlations with the TM gene C1418T polymorphisms. Results: We separated the patients into two groups based on their TM C1418T genotype (CC genotype group and CT/TT genotype group). The days spent in an intensive care unit (ICU) and the incidence of fever in the ICU were significantly lower in the beating-heart CPB and off-pump groups than in the conventional CPB group. Additionally, the TM gene C1418T polymorphisms did not affect the early outcomes in patients in the beating-heart CPB and off-pump groups. Interestingly, in the conventional CPB group, patients with the CC genotype had a lower rate of fever, shorter duration of fever, and delay of ICU when compared with the CT/TT genotype. Conclusion: Surgeons may use a patient’s TM gene C1418T polymorphism to predict the strength of systemic inflammation and speculate on early outcomes during hospitalization before conventional CPB is performed.

Establishing a Proteomics-Based Monocyte Assay To Assess Differential Innate Immune Activation Responses

Innate immune cells are complex systems that can be simultaneously activated in a variety of ways. Common methods currently used to estimate the response of innate immune cells to stimuli are usually biased toward a single mode of activation. The aim of this study was to assess the possibility of designing an assay based on unbiased proteome analysis that would be capable of predicting the complex response of the innate immune system to various challenges. Monocytes were used as representative cells of the innate immune system. The underlying hypothesis was that their proteome response to different activating molecules would reflect the immunogenicity of these molecules. To identify the main modes of response, we treated the human monocytic THP-1 cell line with nine different stimuli. Differentiation and activation were determined to be the two major modes of monocyte response, with PMA causing the strongest differentiation and Pam3CSK4 causing the strongest proinflammatory activation. The established assay was applied to characterize the monocyte response to epidermal growth factor peptide containing isoaspartate, which induced differentiation but not proinflammatory activation. Because of its versatility, robustness, and specificity, this new assay is likely to find a niche among the more established immunological methods.

Does pharmacotherapy influence the inflammatory responses during cardiopulmonary bypass in children?

Cardiopulmonary bypass (CPB) induces a systemic inflammatory response syndrome (SIRS) by factors such as contact of the blood with the foreign surface of the extracorporeal circuit, hypothermia, reduction of pulmonary blood flow during CPB and endotoxemia. SIRS is maintained in the postoperative phase, co-occurring with a counter anti-inflammatory response syndrome. Research on the effects of drugs administered before the surgery, especially in the induction phase of anesthesia, as well as drugs used during extracorporeal circulation, has revealed that they greatly influence these postoperative inflammatory responses. A better understanding of these processes may not only improve postoperative recovery but also enable tailor-made pharmacotherapy, with both health and economic benefits. In this review, we describe the pathophysiology of SIRS and counter anti-inflammatory response syndrome in the light of CPB in children and the influence of drugs used on these syndromes.

Inhibitory CD200R and proapoptotic CD95/CD95L molecules on innate immunity cells are modulated by cardiac surgery

Introduction:

Cardiac surgery directly initiates a systemic inflammatory response with the activation of both cellular and humoral parts of the immune system. Exaggerated immune system activation is associated with a risk of life-threatening multi-organ dysfunction (MOD) and increased morbidity and mortality in the postoperative period. The immune system response is regulated and terminated by inhibitory mechanisms, including the regulatory membrane molecules, such as CD200R, CD95, CD95L and soluble sCD200R.

Methods:

We measured the expression of CD95, CD95L, CD200R and sCD200R molecules in granulocyte and monocyte populations in blood samples of 30 patients who underwent coronary artery bypass grafting (CABG) using cardiopulmonary bypass (CPB). Samples collected before surgery, after surgery and in the postoperative period were analyzed by flow cytometry and ELISA.

Results:

We found a significant increase in the percentage of granulocytes featuring the anti-inflammatory molecule CD200R (from 5% to 17.8%) after surgery. We presume that these cells were less susceptible to apoptosis because they rarely expressed CD95 as the CD200R+CD95– granulocyte sub-population prevailed. Only a small percentage of CD200R+ granulocytes expressed simultaneously CD95 (from 0.5 to 2.06 %). This small population of CD200R+CD95+ cells decreased expression of CD200R after surgery and, thus, was likely to be a source of increased sCD200R in serum (from 96 to 294 ng/mL). Also, the expression of CD95L on CD200R+ granulocytes and CD95 on CD200R+ monocytes was affected by surgery. The percentage of CD200R+ monocytes was elevated on the 1st postoperative day (from 30.6 to 49.4 %) and dropped below the preoperative value on the 7th day after surgery (from 30.6 to 19.8 %). This population comprised mainly CD200R+CD95+ monocytes in which the enhanced expression of CD95 was found.

Conclusion:

Our data show that the expression of CD200R, CD95 and CD95L was influenced by cardiac surgery and imply the role of these membrane molecules in cell regulation–inhibition and apoptosis following cardiac surgery.

Calpain activity and Toll-like receptor 4 expression in platelet regulate haemostatic situation in patients undergoing cardiac surgery and coagulation in mice

Human platelets express Toll-like receptors (TLR) 4. However, the mechanism by which TLR4 directly affects platelet aggregation and blood coagulation remains to be explored. Therefore, in this study, we evaluated the platelet TLR4 expression in patients who underwent CABG surgery; we explored the correlation between platelet TLR4 expression and the early outcomes in hospital of patients. Additionally, C57BL/6 and C57BL/6-Tlr^LPS−/− mice were used to explore the roles of platelet TLR4 in coagulation by platelet aggregometry and rotation thromboelastometry. In conclusion, our results highlight the important roles of TLR4 in blood coagulation and platelet function. Of clinical relevance, we also explored novel roles for platelet TLR4 that are associated with early outcomes in cardiac surgery.

Nutritional Effect of Oral Supplement Enriched in ω-3 Fatty Acids, Arginine, RNA on Immune Response and Leukocyte-platelet Aggregate Formation in Patients Undergoing Cardiac Surgery

The aim of the present study was to investigate the influence of a supplement enriched in ω-3 fatty acids on immune responses and platelet–leukocyte complex formation in patients undergoing cardiac surgery. Patients in the supplement group (n = 7) took a supplement enriched in ω-3 fatty acids (Impact^®) in addition to a hospital diet for five successive days before surgery; those in the control group (n = 7) took only hospital diet and did not take Impact^®. Blood samples in both groups were collected at same time points. Before surgery, samples were collected five days before surgery, at the start of supplementation (baseline), and the end of supplementation (postoperative day (POD)-0). After surgery, samples were collected on POD-1 and POD-7. The expression of human leukocyte antigen (HLA)-DR, the ratio of CD4-/CD8-positive cells, the production of interferon (IFN)-γ by CD4-positive cells, plasma levels of cytokines, and leukocyte–platelet aggregates were measured. Before surgery (POD-0), the supplement caused significant increases in HLA-DR expression, CD4/CD8 ratio, and plasma levels of IFN-γ; these levels were significantly higher compared to those in the control group (P < 0.05, respectively). After surgery (POD-1), all values dramatically decreased in comparison with those of POD-0; however, the values in the supplement group were significantly higher compared to their respective markers in the control group (P < 0.05, respectively). Significant differences of HLA-DR expression and CD4/CD8 ratio persisted through POD-7. Before surgery (POD-0), plasma levels of interleukin (IL)-10 in the supplement group decreased significantly compared with those in the control group (P < 0.05). After surgery (POD-1), plasma levels of IL-10 in both the control and supplement groups increased; these levels in the supplement group were significantly lower than those in the control group (P < 0.05). Significant decreases in the percentage of leukocyte–platelet aggregates were found after supplementation; the difference between the supplement and the control groups was found on POD-0 and POD-1 (P < 0.05, respectively). In conclusion, the dietary supplement increased HLA-DR expression, the CD4/CD8 ratio, and the production of IFN-γ by CD4-positive cells; conversely, the levels of IL-10 and the formation of leukocyte–platelet aggregates before and after surgery were suppressed. These beneficial effects may decrease the incidence of complications after surgery.

Importance of monocyte deactivation in determining early outcome after ventricular assist device implantation

BACKGROUND

Patients undergoing mechanical circulatory support using ventricular assist devices (VADs) experience a postoperative mixed antagonistic (proinflammatory and antiinflammatory) response syndrome. This response can result in immunoparalysis, exposing VAD recipients to infection and interfering with patient recovery despite adequate hemodynamic support. We undertook the present study to evaluate whether postoperative monocytic human leukocyte antigen-DR (mHLA-DR) expression is of prognostic value for mortality or infection of VAD recipients during their initial intensive care unit (ICU) stay after implantation.

METHODS

Since 2004, we have monitored postoperative mHLA-DR expression in 50 VAD recipients using flow cytometry.

RESULTS

Thirty-seven patients (74%) developed infection, and 22 patients (44%) died during their initial ICU stay. mHLA-DR expression was lowest in the immediate postoperative period (postoperative days [PODs] 1-3) but increased progressively thereafter. Multiple regression analysis showed that preoperative aspartate aminotransferase level was the only significant and independent predictor of the percentage of HLA-DR-positive monocytes on PODs 1-3 (β = -0.726, p = 0.0001). ICU death and infection were associated with significantly lower percentages of HLA-DR-positive monocytes on PODs 1-3. ROC curve analysis revealed that the percentage of HLA-DR-positive monocytes on PODs 1-3 had significant discriminative power for ICU death (area under the curve = 0.73, 95% confidence interval, 0.545-0.912, p = 0.037), but not for infection.

CONCLUSIONS

Postoperative mHLA-DR expression was closely related to preoperative hepatic cytolysis. It appeared to be the only early postoperative biological parameter that had some predictive power for death of VAD recipients in the ICU.

Effect of Cardiopulmonary Bypass on Annexin A1 Expression in Peripheral Blood Mononuclear Cells of Children with Congenital Heart Disease

This study aimed to investigate the effect of cardiopulmonary bypass (CPB) on Annexin A1 expression in the peripheral blood mononuclear cells (PBMCs) of children with congenital heart disease (CHD). A total of 30 children receiving CPB for interventricular septal defect were included. Peripheral blood was collected before and after CPB. PBMCs were collected by density gradient centrifugation. Protein extraction was performed by lysis and subjected to 2D-QUANT for protein quantitation. Isoelectric focusing electrophoresis (IEF) was carried out followed by gel image analysis. Protein spots with a difference in expression of >1.5 fold were collected as candidate proteins which were subjected to mass spectrometry for the identification of differentially expressed proteins. Western blot assay was employed to confirm the expressions of target proteins. Peripheral blood collected at two time points was subjected to two-dimensional electrophoresis, and a total of 12 differentially expressed proteins were identified. Of them, 5 proteins had decreased expression before CPB (T0) but their expressions increased after CPB (T1); the remaining 7 proteins had increased expressions before CPB but their expressions reduced after CPB. One of these differentially expressed proteins was Annexin A1. Western blot assay confirmed that Annexin A1 expression began to increase at 0.5 h after CPB, and the increase of Annexin A1 was more obvious after CPB. Our findings primarily indicate the potential mechanism underlying the role of PBMC in inflammatory response following CPB, and provide a target for the prevention and control of post-CPB systemic inflammatory response syndrome (SIRS).

Interferon gamma receptor expression on granulocytes of cardiac surgical patients is modulated differently by the type of cardiopulmonary bypass used

AIMS

To follow the IFNγ receptor expression on monocytes and granulocytes of cardiac surgical patients with respect to the type of cardiopulmonary bypass (CPB).

METHODS

Expression of IFNγ receptor on monocytes and granulocytes of 26 cardiac surgical patients operated with the use of either "standard" or "miniaturised" CPB was determined by flow cytometry.

RESULTS

The significant increase in IFNγ receptor expression on monocytes on the 1(st) and on the 3(rd) postoperative days was revealed in both groups of patients (p<0.001) irrespective of the type of CPB used, being non-significantly different between groups. In contrast, the expression of IFNγ on granulocytes displayed significant differences in terms of the CPB used. Whereas, in "standard" CPB patients, granulocyte INFγ receptor expression reached its maximum immediately after surgery (p<0.01), in "miniivasive" CPB patients, the peak in INFγ receptor expression was postponed to the 1(st) postoperative day (p<0.05). Statistically significantly higher IFNγ receptor expression on granulocytes was found in "standard" CPB patients (p<0.05).

CONCLUSION

Compared to "miniaturised" CPB patients, the significantly higher IFNγ receptor expression on granulocytes was found in "standard" CPB patients (p<0.05) on the 1(st) postoperative day.

Expression of thrombomodulin on monocytes is associated with early outcomes in patients with coronary artery bypass graft surgery

Thrombomodulin (TM) mediates blood coagulation and inflammation and is expressed constitutively on resting monocytes. This expression might be a key regulator of monocyte-related inflammation. Conventional cardiopulmonary bypass (CPB), beating-heart CPB, and off-pump techniques have been used widely in cardiac surgery. Although beating-heart CPB and off-pump techniques have reduced postoperative inflammation significantly, the underlying mechanisms remain unclear. Whether CPB affects the expression of TM and changes the actual immune capacity of monocytes is also unknown. In this study, we analyzed TM expression on monocytes and in plasma among patients undergoing elective coronary artery bypass graft surgery. The days spent in an intensive care unit (ICU) and incidence of fever in the ICU were significantly lower in the beating-heart CPB and off-pump groups than in the conventional CPB group. Enzyme-linked immunosorbent assay showed a significant increase in TM at 30 min after the commencement of CPB and at the end of surgery in the conventional CPB group, whereas the level increased less markedly in the beating-heart CPB group. Flow cytometry showed that conventional CPB markedly reduced the expression of TM on monocytes. Based on monocyte chemotaxis analysis and an actin polymerization assay, we propose that TM expression on monocytes is associated with systemic inflammation. We conclude that the beating-heart CPB and off-pump techniques have a lower impact on patients than conventional CPB. The reduced incidence of fever and shorter ICU stay seem to be associated predominantly with the lower concentration of TM in plasma and with a higher expression of TM on monocytes.

TNF-alpha inhibits toll-like receptor 4 expression on monocytic cells via tristetraprolin during cardiopulmonary bypass

Toll-like receptor 4 (TLR4) plays a major role in regulating the innate immune response, which is related to postoperative complications. Although inflammatory capacity and TNF-alpha synthesis were altered on monocytes after cardiopulmonary bypass (CPB), whether the CPB and the CPB-induced TNF-alpha affect TLR4 expression on monocytes have not yet clarified. We speculate that the changing of TNF-alpha level during CPB may be involved in monocytic TLR4 expression. As previous report, our enzyme-linked immunosorbent assay showed that CPB elevated the plasma level of TNF-alpha, whereas off-pump cardiac surgery does not. Flow cytometry reported decreased levels of monocytic TLR4 in patients undergoing CPB but not undergoing off-pump cardiac surgery. To elucidate whether the CPB-induced TNF-alpha is related to TLR4 down-regulation, we used human monocytic THP-1 cells. Actinomycin D chase experiments demonstrated that TNF-alpha decreased TLR4 expression and TLR4 mRNA stability on THP-1. Confocal microscopy and real-time polymerase chain reaction showed that TNF-alpha induced intracellular tristetraprolin (TTP) expression. Transfection with TTP siRNA reversed the down-regulation of TLR4 in TNF-alpha-stimulated THP-1. Treatment with ERK1/2 inhibitor and SAPK/JNK inhibitor decreased TNF-alpha-induced TTP expression. Immunoprecipitation and Western blot analysis showed that the TNF-alpha-mediated activation of TTP might be inhibited by p38 mitogen-activated protein kinase inhibitor and by PD98059. We also demonstrated in clinical samples with confocal microscopy and flow cytometry that CPB led to an elevation of TTP in monocytes. In conclusion, CPB and TNF-alpha decrease TLR4 expression on monocytes; TTP expression and mitogen-activated protein kinase-signaling pathways play critical roles in CPB- and TNF-alpha-mediated decreases of TLR4 on monocytes. Our results suggest that using TTP to control cytokine message decay rate may be a promising approach for controlling system inflammation and preventing post-CPB complications.

Major hepatectomy induces phenotypic changes in circulating dendritic cells and monocytes

INTRODUCTION

Patients undergoing major hepatectomy are at increased risk for post-operative morbidity and mortality, and changes in the phenotype of effector cells may predispose these patients to infectious sequelae.

METHODS

To better understand post-hepatectomy immune responses, peripheral blood from 15 hepatectomy patients was drawn immediately before and after liver resection and on post-operative days 1, 3, and 5. Circulating monocytes and dendritic cells were analyzed by flow cytometry for quantity, phenotype, activation status, human leukocyte antigen DR (HLA-DR) expression, and toll-like receptor-2 and -4 expression.

RESULTS

Major hepatectomy increased the numbers of activated CD16(bright) blood monocytes and the percentage of activated dendritic cells, although monocyte HLA-DR expression was reduced. These results may represent both dysfunctional antigen presentation and pending anergy, as well as cellular priming of immune effector cells. Better understanding of the alterations in innate immunity induced by hepatectomy may identify strategies to reduce infectious outcomes.

Expression of Toll-like receptors 2 and 4 on innate immunity cells modulated by cardiac surgical operation

OBJECTIVE

This study aimed to follow-up on the changes in the expression of Toll-like receptors (TLRs) on monocytes and granulocytes in venous blood of patients undergoing cardiac surgical operation.

MATERIAL AND METHODS

TLR2 and TLR4 expression on blood cells was determined by flow cytometry in 40 patients undergoing cardiac surgery performed either with cardiopulmonary bypass (CPB) ("on-pump") or without it ("off-pump").

RESULTS

Intensity of the expression of TLR2 on both monocytes and granulocytes, expressed as median fluorescence intensity, is significantly reduced during CPB, being lower in both groups at the finish of surgery. These changes are not so remarkable in the case of TLR4 expression. Compared to "on-pump" patients, there is a higher relative number of TLR2(+) granulocytes in "off-pump" patients at the finish of surgery and of TLR4(+) granulocytes on the first postoperative day.

CONCLUSIONS

We found characteristic patterns in the expression of TLR2 and TLR4 on monocytes and granulocytes in venous blood of patients undergoing cardiac surgery with or without CPB.

A comparison of monocyte counts and ex vivo and in vitro monocyte cytokine production after major surgical trauma

BACKGROUND

Impaired function of cluster of differentiation 14-positive (CD14+) monocytes (MOs) after major surgical trauma is believed to predispose to infectious complications. Postoperative decreases in human leukocyte antigen (HLA)-DR expression, tumor necrosis factor-alpha (TNF-alpha) production and interleukin (IL)-12 synthesis have been reported. There are no studies comparing absolute MO counts and MO cytokine synthesis in peripheral blood and stimulated cultures.

METHODS

The study group included 10 low-risk patients undergoing elective cardiac surgery with extracorporeal circulation. Preoperatively (d0) and on the first (d1) and third (d3) postoperative d, we analyzed leukocyte counts, CD14+ MO absolute counts, HLA-DR expression, and stimulated IL-12 and TNF-alpha synthesis using flow cytometry. In addition, IL-12 and TNF-alpha release in stimulated whole blood cultures was assayed.

RESULTS

Whereas the absolute numbers of leukocytes and CD14+ MOs were significantly elevated, HLA-DR expression was suppressed postoperatively. The proportion of TNF-alpha- and IL-12-producing MOs was reduced after surgery. This, however, led to a significant postoperative decrease only in the absolute numbers of peripheral blood IL-12+ MOs. IL-12 secretion was postoperatively reduced in whole blood cultures. The IL-12-synthesizing capacity of IL-12+ MOs was significantly reduced only on d1.

CONCLUSIONS

The immediate postoperative period is associated with an increase in the absolute MO numbers and an impairment of MO function, which is reflected in a reduced capacity to synthesize IL-12 and TNF-alpha and a decreased ability to express HLA-DR and present antigens. Whereas the cytokine-producing capacity returns to normal levels on d3, the suppression of HLA-DR expression persists.

PDMS content affects in vitro hemocompatibility of synthetic vascular grafts

An unsolved problem when employing small-diameter vascular grafts for aorto-coronary by-pass and peripheral reconstruction is the early thrombotic occlusion. The PEtU-PDMS is a new elastomeric material, composed of poly(ether)urethane and polydimethylsiloxane, synthesized to realize grafts with improved hemocompatibility characteristics. In order to investigate the effect of PDMS content on hemocompatibility, three different percentages of PDMS containing grafts (10, 25 and 40) were evaluated. Grafts realized with Estane 5714-F1 and silicone medical grade tubes were used as references. The hemocompatibility was investigated by an in vitro circuit in which human anticoagulated blood was circulated into grafts by a peristaltic pump modified to obtain a passive flow. For each experiment, 40 cm length graft was closed into a circular loop and put in rotation for 2 h at 37 degrees C. At the end of the experiments different parameters regarding platelet adhesion and activation were evaluated: circulating platelets count, beta-thromboglobulin release, platelet CD62P expression and amount of monocyte-platelet conjugates. PEtU-PDMS grafts with 25 and 40% of PDMS induced the lowest platelet adhesion, plasma level of beta-TG and amount of monocyte-platelet conjugates. No significative variations were observed in CD62P expression. In conclusion, PDMS content significatively affects blood-graft surface interaction, in fact higher PDMS percentage containing grafts showed the best in vitro hemocompatibility.

ALTERATIONS IN INFLAMMATORY CAPACITY AND TLR EXPRESSION ON MONOCYTES AND NEUTROPHILS AFTER CARDIOPULMONARY BYPASS

Cardiopulmonary bypass (CPB) is associated with immune paresis, which predisposes to the development of postoperative sepsis. The aims of this study were to characterize the ex vivo cytokine responses to bacterial cell wall components in whole blood from patients undergoing CPB and to determine whether altered leukocyte expression of Toll-like receptors (TLRs) is involved in immune paresis after CPB. We recruited 6 patients undergoing routine cardiac surgery with CPB. Preoperatively, at the end of CPB and 20 h later, blood was obtained, anticoagulated, and leukocyte surface expression of CD14, TLR2, and TLR4 was quantified by flow cytometry. In addition, blood was incubated at 37 degrees C in the presence of peptidoglycan (PepG) and/or lipopolysaccharide (LPS), and plasma cytokines were measured by enzyme immunoassay. At the end of CPB, ex vivo production of tumor necrosis factor alpha, interleukin (IL) 1beta, IL-8, and IL-10 in response to PepG or LPS was virtually abolished (P < 0.05). The following day, there was recovery of all cytokine responses to PepG. Tumor necrosis factor alpha and IL-1beta responses to LPS partially recovered, whereas IL-8 and IL-10 responses recovered. At the end of CPB, there was more than 50% reduction in neutrophil TLR2 and TLR4 expression (P < 0.05), with recovery to baseline the following day. There was a 29% reduction in monocyte TLR4 expression at the end of CPB (P < 0.05) and more than 120% increase in monocyte TLR2 and 4 expression the following day (P < 0.05). In conclusion, reduced ex vivo production of cytokines cannot be fully accounted for by downregulation of TLR expression, although receptor upregulation may contribute to the later recovery of responsiveness.

An increased platelet–leukocytes interaction at the culprit site of coronary artery occlusion in acute myocardial infarction: A pathogenic role for “no-reflow” phenomenon?

BACKGROUND

Distal protection devices have been shown to reduce the incidence of "no flow" phenomenon during primary percutaneous coronary intervention (PCI). So far, it has not been well clarified which mechanism is mainly involved in distal coronary protection.

AIM

To investigate the activation state of leukocytes and platelets locally present within the blood from the site of coronary occlusion.

METHODS

Ten patients with acute myocardial infarction (AMI) underwent primary PCI with an embolization protection device and aspiration catheter (PercuSurge GuardWire) were included. The following functional parameters: a) monocyte and neutrophils surface molecules; b) platelet surface activatory antigens; c) leukocytes-platelet conjugates were studied by flow cytometry in blood obtained from the site of coronary occlusion and from peripheral femoral artery.

RESULTS

The leukocyte-platelet adhesion index was significantly higher in the aspirated blood at the site of coronary occlusion than in the peripheral arterial blood for both monocytes (0.226+/-0.04 vs. 0.084+/-0.01; p=0.004) and neutrophils (1.372+/-0.3 vs. 0.524+/-0.1; p=0.02). Moreover, the volume of coaggregates exhibited a significant increase in coronary blood for both populations (p=0.02 for monocytes and for neutrophils). Interestingly, a significant up-regulation of the adhesive molecule CD18 was observed in coronary blood respect to systemic circulation either in monocytes (p=0.01) than in neutrophils (p=0.003). A significant up-regulation of monocyte (HLA-DR) and neutrophil (CD66b) activatory molecules expression was also observed in the aspirated coronary compared to peripheral artery blood (p=0.02 and p=0.03 for HLA-DR and CD66b, respectively).

CONCLUSIONS

These data indicate an increased leukocyte-platelet functional interaction in AMI at the site of plaque rupture relative to the systemic circulation, which may be one of the pathogenetic mechanisms responsible for myocardial "no-reflow" phenomenon.

In Vitro Restoration of Post-Operatively Decreased IFN-Gamma Levels After Cardiac Surgery and Its Effect on Pro- and Anti-Inflammatory Mediators

BACKGROUND

A decreased synthesis of interferon gamma (IFN-gamma) by TH 1 lymphocytes after cardiac operations with cardiopulmonary bypass (CPB) is part of the inflammatory response to local operative and systemic traumas. The consequences of this mechanism on the release of pro- and anti-inflammatory cytokines remain unclear. To evaluate the role of IFN-gamma, we added recombinant IFN-gamma to peripheral blood mononuclear cells (PBMCs) on the first post-operative day in an attempt to restore pre-operative values and then measured the release of pro- and anti-inflammatory cytokines in vitro.

METHODS

PBMCs of 10 patients scheduled for elective coronary artery bypass grafting (CABG) were obtained pre-operatively (d0) and on the first (d1) and third (d3) post-operative days. The release of IL-6, IL-8, TNF-alpha, IFN-gamma, IL-10, IL-2, and IL-4 was studied after stimulation (48 h) with PHA (phytohemagglutinin) and LPS (lipopolysaccharide) in the absence or presence of recombinant human IFN-gamma.

RESULTS

Endogenous IFN-gamma synthesis was suppressed on d1. Adding exogenous IFN-gamma restored IFN-gamma levels to normal on d1 and doubled IFN-gamma levels on d0 and d3. The addition of IFN-gamma increased TNF-alpha levels up to 250% on d1 and IL-2 synthesis by 75% on d1 and d3; the IL-2 levels, however, were still significantly depressed. The addition of recombinant IFN-gamma did not affect the synthesis of IL-6, IL-8, IL-10, and IL-4.

CONCLUSIONS

Contrary to our expectations, the in vitro release of IL-6 and IL-8 as well as IL-10 and IL-4 was not influenced by the addition of IFN-gamma. However, TNF-alpha production in isolated PBMC cultures increased significantly on the first post-operative day. This may indicate a hyper-reactivity of PBMCs to IFN-gamma and suggests that the decrease in IFN-gamma synthesis might prevent an excessive stimulation of the non-specific immune system by high TNF-alpha levels after cardiac surgery.

Is Interferon Gamma Suppression After Cardiac Surgery Caused by a Decreased Interleukin-12 Synthesis?

BACKGROUND

The suppression of interferon gamma (IFN-gamma) synthesis after cardiac surgery is discussed as a cause of postoperative immunosuppression that predisposes to postoperative infectious complications. Because several studies have suggested that interleukin-12 (IL-12) production by monocytes and macrophages is reduced after cardiac surgery, this might cause a decrease in IFN-gamma release. To better understand these processes, we assessed the role of IL-12 in IFN-gamma synthesis in vitro before and after cardiac surgery.

METHODS

Heparinized whole blood samples were obtained from 20 patients undergoing elective cardiac surgery preoperatively (day 0) and on the first (day 1), third (day 3), and fifth (day 5) postoperative days, and stimulated (24 hours) with staphylococcal enterotoxin B and lipopolysaccharide. Recombinant IL-12 was added at each time point investigated. Interferon-gamma, IL-12, IL-2, IL-4, and IL-5 concentrations and histocompatibility leukocyte antigen-DR (HLA-DR) expression on monocytes and macrophages were assayed by flow cytometry.

RESULTS

The HLA-DR expression, IL-12 release, and IFN-gamma synthesis were significantly reduced on day 1, day 3, and day 5. Recovery began on day 3. Interleukin-12 caused a significant increase in IFN-gamma synthesis at each time point. When IL-12 was added, IFN-gamma synthesis returned to preoperative levels on days 3 and 5.

CONCLUSIONS

The synthesis of IFN-gamma is significantly reduced after cardiac surgery. The application of IL-12 causes an increase in IFN-gamma synthesis before surgery and a return of IFN-gamma to preoperative levels within a few days after surgery. These findings suggest that postoperative suppression of IFN-gamma release is caused by a decrease in IL-12 synthesis. In addition, IL-12 has a mainly proinflammatory effect both before and after surgery.

Expression of CD97 and Adhesion Molecules on Circulating Leukocytes in Patients Undergoing Coronary Artery Bypass Surgery

OBJECTIVE

Leukocyte activation is thought to be responsible for the adverse effects and postoperative complications following cardiopulmonary bypass (CPB). A novel cell surface molecule, CD97, is a sensitive marker of leukocyte and primary lymphocyte activation. The present study aimed to determine the activation of different leukocyte subsets by comparing the expression of CD97 and adhesion molecules (CD11, CD18) in patients receiving coronary surgery with or without CPB.

METHODS

30 patients were enrolled and scheduled for coronary bypass surgery under CPB (20 patients, group A) and with off-pump (OP) operation (10 patients, group B). Blood samples were taken before and during surgery, and over the following first week.

RESULTS

Here, we report an early decrease in CD97 expression of granulocytes (PMN) and monocytes (MC) followed by an intensive increase reaching the maximum on postoperative days 2 and 3 in patients operated with CPB. The rate of active CD97-positive lymphocytes showed a marked, gradual increase until postoperative day 3 and remained elevated up to day 7 after CPB. OP surgery resulted in moderate alteration in the presence of CD97 on PMN, MC and lymphocytes. The expression of adhesion molecules was similar to CD97 in all leukocyte subsets.

CONCLUSION

The findings about CD97 expression suggest considerable leukocyte activation following coronary bypass with CPB compared to OP surgery. The collected data show that the lymphocytes are highly activated and involved in leukocyte sequestration after CPB. Moreover, the importance of CD97 in CPB-related inflammatory response can be stated.

Post-reperfusion changes of monocyte function in coronary blood after extracorporeal circulation

BACKGROUND

Neutrophil and mononuclear cell functional changes represent a hallmark of inflammation during cardiopulmonary bypass and cardiovascular surgery. Knowledge of mechanisms underlying monocyte functional modulation in coronary blood may be useful to develop protective interventions that can limit ischemia/reperfusion injury.

METHODS

Samples of 13 patients were drawn from venous coronary sinus before cardioplegic arrest and after reperfusion. The following parameters were studied: surface molecules expression (CD18, CD11b, CD44, CD162, CD15s, CD80, CD86, CD16, CD49d, CD29, CD25, HLA-DR, Toll-like receptor-4 [TLR-4], CXCR1, CCR2, CCR5, CX3CR1), oxidative burst response, monocyte-platelet conjugates (using antibodies against CD45, CD14, CD41a), and platelet activation (CD62P, PAC-1). Enzyme-linked immunosorbent assays were performed to measure levels of interleukin (IL)-1beta, IL-6, IL-8, IL-10, and tumor necrosis factor-alpha (TNF-alpha).

RESULTS

Coronary reperfusion down-modulated monocyte molecules expression, especially for CD18 (P = 0.048), CD44 (P = 0.0035), CD49d (P = 0.0029), CD29 (P = 0.032), HLA-DR (P < 0.0001), TLR-4 (P = 0.0109), CCR2 (P = 0.0184), CCR5 (P = 0.0396), and CX3CR1 (P < 0.0001). A marginal increase (P = 0.062) of a normalized adhesion index between monocytes and platelets was observed at reperfusion. No variations were detected for the monocyte oxidative burst and platelet activation. Increased levels of IL-6 (P = 0.013), TNF-alpha (P = 0.0272), and IL-10 (P = 0.0008) were measured after cardioplegia.

CONCLUSIONS

The lack of CD11b and CD25 variations and of the oxidative burst exclude monocyte activation at reperfusion. The high after-cardioplegia level of IL-10, the decreased expression of HLA-DR and TLR-4, and the absence of IL-1beta and IL-8 suggest an IL-10-mediated functional depression of monocyte, including their adhesive and migratory capacities. The lack of an after-cardioplegia orientation toward IL-10 producing a "macrophage-like" CD14+/CD16+ phenotype might mean that myocardial infiltrating lymphocytes are the main source of IL-10. Moreover, the increased after-cardioplegia levels of IL-6 and TNF-alpha might be due to myocardial and endothelial activations. The increased adhesion index between monocyte and platelets, without receptor variations, suggests a monocyte membrane modification induced by extracorporeal circulation.

Role of granulocytes and monocytes in the polyvinyl chloride-induced synthesis of interleukin 8, monocyte chemoattractant protein 1, and leukotriene B4

In an in vitro whole blood model of artificial surface-induced inflammation, we have studied the contribution of leukocyte populations in the synthesis of inflammatory mediators. This was done by depleting the blood of specific cell types using magnetic beads coated with monoclonal antibodies against leukocyte surface antigens. Synthesis of interleukin 8 (IL-8) was highly dependent on CD15+ cells and was reduced by 80% when these cells were removed from the blood. Correspondingly, IL-8 production showed a high correlation with the concentration of granulocytes (r = 0.77, p < 0.0001). Synthesis of monocyte chemoattractant protein 1 (MCP-1) was dependent on CD14+ cells and was reduced by 35% when these cells were removed from the blood. Correspondingly, MCP-1 production correlated with the concentration of monocytes (r = 0.39, p < 0.0001). Synthesis of leukotriene B4 (LTB4) was highly dependent on CD15+ cells and was reduced by 75% when these cells were removed from the blood. Correspondingly, LTB4 production correlated strongly with the granulocyte concentration (r = 0.54, p < 0.0001). As expected, complement activation was not affected by cell depletion and did not correlate with the concentration of any of the cell types. Thus, artificial surface-induced IL-8 and LTB4 synthesis was almost exclusively granulocyte dependent. However, MCP-1 synthesis was mainly a product of monocytes, although granulocytes and other subpopulations may partly contribute. (c) 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005.