Time course of beta 2-integrin CD11b/CD18 (Mac-1, alpha M beta 2) upregulation on neutrophils and monocytes after coronary artery bypass grafting. CD11b upregulation after CABG surgery

Temporal leukocyte numbers and granulocyte activation in pulsatile and rotary ventricular assist device patients

Individual ventricular assist device (VAD) design may affect leukocytes and impact immunity. Few studies have presented leukocyte and infection profiles in VAD patients over the course of the implant period. CD11b (MAC-1) expression on granulocytes is an indicator of activation during inflammation, mediating extravasation and the release of reactive oxygen species in tissue. No reported studies have presented MAC-1 expression on circulating granulocytes in VAD patients. Fifty-six patients implanted at a single center with a HeartMate II (HMII; n = 32), HeartWare (HW; n = 12), or Thoratec pneumatic VAD (PVAD; n = 12) between 1999 and 2011 were followed for 120 days of support. The leukocyte profiles and infectious events of all patients were evaluated; additionally, a subset had MAC-1 expression on circulating granulocytes was measured (HMII n = 9; HW n = 7; PVAD n = 4). All groups exhibited a significant peak in leukocyte numbers at postoperative day (POD) 14 while simultaneously experiencing a significant decrease in hematocrit. HMII patients exhibited a 3.2-fold increase in granulocyte MAC-1 expression at POD 14, and the temporal trend over the implant period differed from that experienced by HW patients. Further, HW patients experienced significantly fewer infection events. Alterations in leukocyte profiles and granulocyte activation experienced by VAD patients appear to be device-specific. Elevations in leukocyte activation may be related to an increased risk for infection, although the specific relationship between these phenomena in this patient group is not known.

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.

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.

Biomaterial-associated thrombosis: roles of coagulation factors, complement, platelets and leukocytes

Our failure to produce truly non-thrombogenic materials may reflect a failure to fully understand the mechanisms of biomaterial-associated thrombosis. The community has focused on minimizing coagulation or minimizing platelet adhesion and activation. We have infrequently considered the interactions between the two although we are generally familiar with these interactions. However, we have rarely considered in the context of biomaterial-associated thrombosis the other major players in blood: complement and leukocytes. Biomaterials are known agonists of complement and leukocyte activation, but this is frequently studied only in the context of inflammation. For us, thrombosis is a special case of inflammation. Here we summarize current perspectives on all four of these components in thrombosis and with biomaterials and cardiovascular devices. We also briefly highlight a few features of biomaterial-associated thrombosis that are not often considered in the biomaterials literature: The importance of tissue factor and the extrinsic coagulation system. Complement activation as a prelude to platelet activation and its role in thrombosis. The role of leukocytes in thrombin formation. The differing time scales of these contributions.

Monocyte Fc gamma receptor expression in patients undergoing coronary artery bypass grafting

BACKGROUND

Cardiopulmonary bypass is associated with an inflammatory response with potential deleterious effects. The white cell subpopulation mostly investigated so far is the neutrophil. To date very little has been investigated regarding the role of the monocyte/macrophage. This study focuses on the expression of Fc gamma receptors I, II, and III by monocytes in patients undergoing cardiopulmonary bypass.

METHODS

We studied the surface expression of Fc gamma receptors I, II, and III by flow cytometry on gated monocyte subpopulations in the whole blood of adult patients undergoing elective coronary artery bypass grafting. Blood samples were drawn preoperatively and at 15 minutes, 1, 2, 4, 24, 48, and 72 hours, and 6 days postoperatively. A second group of patients undergoing lung resection surgery were studied in a similar fashion.

RESULTS

Neither Fc receptor I nor receptor II expression were significantly changed throughout the time points studied. Fc receptor III expression was reduced at 2 and 4 hours (p = 0.016 and 0.002) and increased at 24, 48, and 72 hours after commencement of CPB on a selected subpopulation (15%-35%) of monocytes (p = 0.004, < 0.001, and < 0.001, respectively). This expression returned to preoperative levels by the sixth postoperative day. There were no statistically significant changes in the lung resection group.

CONCLUSIONS

Our study demonstrated that cardiopulmonary bypass is associated with a biphasic Fc gamma receptor III expression on a subpopulation of peripheral blood monocytes up to 3 days postoperatively.

Monocyte and neutrophil adhesion molecule expression during acute hyperglycemia and after antioxidant treatment in type 2 diabetes and control patients

OBJECTIVE

We hypothesized that acute hyperglycemia (an independent cardiovascular risk factor) increases the expression of proatherogenic leukocyte adhesion molecule in type 2 diabetes and controls and that the expression of these adhesion molecules would be antioxidant sensitive.

METHODS AND RESULTS

Twenty-three type 2 diabetes patients and 13 control patients underwent two oral glucose tolerance tests 14 days apart and took placebo or 800 IU daily of oral alpha tocopherol between tests. Monocyte and neutrophil expression of adhesion molecules Mac-1, LFA-1 and 3, ICAM-1, and VLA-4 were measured at 0, 120, and 240 minutes by using laser flow cytometry. Baseline adhesion molecule expression did not differ between groups, but there was a rapid, highly significant increase (P<0.0001) in the intensity of monocyte Mac-1 expression after a glucose load in both groups. Alpha-tocopherol supplementation reduced only Mac-1 expression in the diabetes group (P=0.03).

CONCLUSIONS

Acute glycemic excursions of any degree cause highly significant, rapid increases in monocyte Mac-1 expression in type 2 diabetes patients and controls. Mac-1 mediates leukocyte vascular infiltration and is prothrombotic. These data suggest a mechanism for the link between glycemic excursions and increased vascular event rates.

Neutrophil activation in immunoadsorption

Immunoadsorption therapy (IAT) is used in the treatment of autoimmune diseases. Although IAT has been reported to modify humoral immunity by inducing chemokines and activating complements, much remains unknown about the biological effects of IAT on cellular components in peripheral blood. To define the influence of IAT on leukocytes, we determined leukocyte L-selectin (CD62L) and Mac-1 (CD11b) as parameters for activation of leukocytes in peripheral blood during IAT. Peripheral leukocyte L-selectin and Mac-1 were determined continuously by flow cytometry in 6 patients with neuroimmunological disorders in whom IAT was conducted using a Plasma Flow OP-05 (Asahi Medical Corp., Tokyo, Japan) as a plasma separator and Immusorba TR-350 (Asahi Medical Corp., Tokyo, Japan) as an adsorption column. Expression of neutrophils (PMN) L-selectin was decreased 30 min after starting IAT, with the decreases particularly marked at the end of IAT, while expression of mononuclear cells (MNC) L-selectin slightly increased during IAT. Expression of PMN Mac-1 was markedly increased at the end of IAT, whereas expression of MNC Mac-1 did not change during IAT. Leukocyte counts decreased 30 min after starting IAT, and then increased to the initial level or higher in parallel with L-selectin downregulation and Mac-1 upregulation on PMN. L-selectin downregulation and Mac-1 upregulation on PMN suggested that activation of PMN associated with changes in peripheral leukocyte counts occurred during IAT and might play some role in modulating the human circulating blood and immune systems.

Integrin expression on neutrophils in a rabbit model of Group B Streptococcal meningitis

Products released by polymorphonuclear cells (PMNs) during an acute inflammatory response can result in diffuse tissue injury. Integrins are cell surface adhesion proteins that play a pivotal role in inflammation by allowing PMNs to adhere to the endothelium and migrate through the extracellular matrix. We examined the expression of beta1 and beta2 integrins on neutrophils from blood and cerebrospinal fluid (CSF) in an animal model of Group B Streptococcal meningitis. We further evaluated whether integrin expression correlates with pathophysiologic markers of central nervous system inflammation. Our data demonstrate that beta3 and beta2 integrin expression on circulating neutrophils does not significantly increase as a consequence of meningitis. In extravesated CSF neutrophils, a significant increase in expression of both beta1 and beta2 integrins is noted. Furthermore, a majority of the beta1 integrins on extravesated neutrophils have undergone affinity modulation. Using regression analysis, we demonstrated that increasing beta1 integrin expression correlates with decreasing CSF glucose concentration and serum/CSF glucose ratio. Regression analysis approached significance when CSF protein was compared to PMN beta1 integrin expression. Polymorphonuclear leukocytes beta1 integrin expression also showed a direct correlation to myeloperoxidase activity in brain tissue. Beta2 expression on CSF PMNs did not correlate with these markers of inflammation/sequestration. These data demonstrate integrin expression on extravesated neutrophils markedly increases during meningitis and support a role for beta1 integrins on neutrophils in the pathophysiologic consequences of meningitis.

Differential expression of neutrophil adhesion molecules during coronary artery surgery with cardiopulmonary bypass

BACKGROUND

Activation of neutrophil adhesion molecules and subsequent neutrophil adhesion to vascular endothelium are key events initiating inflammatory organ dysfunction after cardiopulmonary bypass and ischemic reperfusion.

OBJECTIVES

We sought to characterize neutrophil integrin CD11b and L-selectin activation associated with coronary artery bypass graft surgery and to determine whether neutrophil activation contributes to their sequestration on postbypass reperfusion.

METHODS

Twenty patients undergoing routine coronary artery bypass were studied. Heparinized whole blood was simultaneously sampled from a central venous line, aorta, coronary sinus, and right and left atrium before, during, and up to 20 minutes after cardiopulmonary bypass. Neutrophil counts were obtained, and neutrophil CD11b and L-selectin expression was determined by flow cytometric analysis in whole blood.

RESULTS

CD11b expression on circulating neutrophils increased during cardiopulmonary bypass, peaking at 145% of baseline level after release of the aortic clamp and then declined by 20 minutes after bypass (analysis of variance, P =.003). No change in neutrophil L-selectin expression was observed during cardiopulmonary bypass. Neutrophils responded to ex vivo stimulation by C5a and leukotriene B(4) during cardiopulmonary bypass but not at 24 hours after the operation. After reperfusion, neutrophil loss, but not local activation, was demonstrated in the coronary and pulmonary circulations.

CONCLUSIONS

Upregulated CD11b expression on neutrophils is likely to contribute to neutrophil sequestration in the heart and lungs after bypass, but neutrophil activation may be limited by their reduced responsiveness to agonist stimulation. CD11b represents a potential therapeutic target for diminishing inflammation after cardiac operations.

Mechanisms and consequences of phagocyte adhesion to endothelium

Leukocyte adhesion to endothelium is essential for the development of an appropriate immune-inflammatory response. The vital importance of leukocyte-endothelial adhesive interactions in host defense and homeostasis is illustrated by the clinical manifestations of patients with congenital defects of leukocyte adhesion functions. However, under some circumstances leukocyte adhesion to endothelium may instead lead to vascular and tissue damage. In recent years, there has been remarkable progress in the understanding of the molecular basis of leukocyte adhesion to endothelium, and this knowledge has led to a new approach to immunomodulation in human disease, ie 'antiadhesion' therapy. This review focuses on cell adhesion molecules mediating adhesion of circulating phagocytes to vascular endothelium, on congenital defects of phagocyte adhesion in man, and on the current status of antiadhesion therapy directed towards phagocyte and endothelial adhesion molecules. We will also consider markers of phagocyte activation, which may provide a means to identify those patients who would benefit most from antiadhesion therapy.

Effects of cardiopulmonary bypass on leukocyte and endothelial adhesion molecules

During the inflammatory response, triggered by cardiopulmonary bypass, interaction between activated leukocytes, platelets, and endothelial cells is mediated through the expression of three main groups of adhesion molecules: the selectins, the integrins, and the immunoglobulin superfamily. The selectins, which mediate the initial rolling of the leukocyte on the endothelium, are divided in three subgroups: L-selectin is expressed on all three leukocyte types, P-selectin is expressed on platelets and endothelial cells, and E-selectin is only expressed on endothelial cells. Integrins can be found on most cell types, consist of an alpha and a beta subunit and mediate firm adhesion of the leukocyte and migration into the tissues. They are classified into subgroups according to the type of their beta subunit. Immunoglobulins such as ICAM-1 and VCAM-1 are expressed mainly on endothelium and act as ligands for certain integrins. This review article summarizes the existing, and rapidly expanding, literature concerning the effects of cardiopulmonary bypass on the expression of leukocyte and endothelial adhesion molecules. Deeper understanding of the, behavior and the role of adhesion molecules during cardiopulmonary bypass may facilitate effective intervention in the inflammatory response process and suppression of its adverse effects.

Visceral ischemia and neutrophil activation in sepsis and organ dysfunction

BACKGROUND

It has previously been shown that a rise in intraoperative neutrophil CD11b expression during supracoeliac cross-clamping is a marker for subsequent development of postoperative organ dysfunction. Prolonged visceral ischemia and increased aneurysm extent are associated with higher risks of morbidity and mortality after TAAA repair. This study investigates the relationship between visceral ischemia and neutrophil activation in sepsis and organ dysfunction following visceral reperfusion.

METHOD

Fifty-one patients undergoing supracoeliac cross-clamping, 5 patients undergoing suprarenal clamping, and 8 patients undergoing infrarenal clamping for repair of aortic aneurysms were studied. Perioperative neutrophil CD11b expression was measured by flow cytometry.

RESULTS

There was significant correlation between visceral clamp time and intraoperative CD11b expression. More extensive aneurysms resulted in increased visceral clamp times and CD11b expression. There were no differences between bypass and non-bypass-assisted surgery with regard to neutrophil expression. There were increased clamp time in patients who developed severe sepsis and postoperative organ dysfunction. Differences in preoperative levels of CD11b expression were observed between groups and high levels of preoperative CD11b expression were observed in patients who died intraoperatively, in type II patients who went on to develop severe sepsis and organ failure, and in patients who developed multiple organ failure rather than single organ failure.

CONCLUSION

Longer periods of visceral ischemia are associated with higher levels of intraoperative CD11b expression, severe sepsis, and organ failure. High preoperative levels of CD11b may identify an "at-risk" subset of patients.