An investigation of the effects of heparin, low molecular weight heparin, protamine, and fentanyl on the balance of pro- and anti-inflammatory cytokines in in-vitro monocyte cultures

Neurocognitive Function after Cardiac Surgery: From Phenotypes to Mechanisms

For half a century, it has been known that some patients experience neurocognitive dysfunction after cardiac surgery; however, defining its incidence, course, and causes remains challenging and controversial. Various terms have been used to describe neurocognitive dysfunction at different times after cardiac surgery, ranging from "postoperative delirium" to "postoperative cognitive dysfunction or decline." Delirium is a clinical diagnosis included in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Postoperative cognitive dysfunction is not included in the DSM-5 and has been heterogeneously defined, though a recent international nomenclature effort has proposed standardized definitions for it. Here, the authors discuss pathophysiologic mechanisms that may underlie these complications, review the literature on methods to prevent them, and discuss novel approaches to understand their etiology that may lead to novel treatment strategies. Future studies should measure both delirium and postoperative cognitive dysfunction to help clarify the relationship between these important postoperative complications.

Low molecular weight heparin relieves experimental colitis in mice by downregulating IL-1β and inhibiting syndecan-1 shedding in the intestinal mucosa

Low molecular weight heparin (LMWH) exhibits anti-inflammatory properties, but its effect on inflammation in colitis remains unclear. This study aimed to evaluate the therapeutic effects of LMWH on dextran sulfate sodium (DSS)-induced colitis in mice, in which acute colitis progresses to chronic colitis, and to explore the potential mechanism involved in this process. C57BL/6 mice were randomly divided into control, DSS, and DSS plus LMWH groups (n = 18). Disease activity was scored by a disease activity index (DAI). Histological changes were evaluated by hematoxylin and eosin (HE) staining. The mRNA levels of syndecan-1, interleukin (IL)-1β, and IL-10 were determined by quantitative reverse transcription polymerase chain reaction. Protein expression of syndecan-1 was detected by immunohistochemistry. The serum syndecan-1 level was examined by a dot immunobinding assay. LMWH ameliorated the disease activity of colitis induced by DSS administration in mice. Colon destruction with the appearance of crypt damage, goblet cell loss, and a larger ulcer was found on day 12 after DSS administration, which was greatly relieved by the treatment of LMWH. LMWH upregulated syndecan-1 expression in the intestinal mucosa and reduced the serum syndecan-1 level on days 12 and 20 after DSS administration (P<0.05 vs. DSS group). In addition, LMWH significantly decreased the expression of both IL-1β and IL-10 mRNA on days 12 and 20 (P<0.05 vs. DSS group). LMWH has therapeutic effects on colitis by downregulating inflammatory cytokines and inhibiting syndecan-1 shedding in the intestinal mucosa.

Opioids and clonidine modulate cytokine production and opioid receptor expression in neonatal immune cells

OBJECTIVE

Opioids and clonidine, used in for sedation, analgesia and control of opioid withdrawal in neonates, directly or indirectly activate opioid receptors (OPRs) expressed in immune cells. Therefore, our objective is to study how clinically relevant concentrations of different opioids and clonidine change cytokine levels in cultured whole blood from preterm and full-term infants.

STUDY DESIGN

Using blood from preterm (≤ 30 weeks gestational age (GA), n=7) and full-term ( ≥ 37 weeks GA, n=19) infants, we investigated the changes in cytokine profile (IL-1β, IL-6, IL-8, IL-10, IL-12p70 and TNF-α), cyclic adenosine monophosphate (cAMP) levels and μ-, δ- and κ- opioid receptor (OPR) gene and protein expression, following in-vitro exposure to morphine, methadone, fentanyl or clonidine at increasing concentrations ranging from 0 to 1 mM.

RESULT

Following lipopolysaccharide activation, IL-10 levels were 146-fold greater in cultured blood from full-term than from preterm infants. Morphine and methadone, but not fentanyl, at >10(-5) M decreased all tested cytokines except IL-8. In contrast, clonidine at <10(-9) M increased IL-6, while at >10(-5) M increased IL-1β and decreased TNF-α levels. All cytokine changes followed the same patterns in preterm and full-term infant cultured blood and matched increases in cAMP levels. All three μ-, δ- and κ-OPR genes were expressed in mononuclear cells (MNC) from preterm and full-term infants. Morphine, methadone and clonidine, but not fentanyl, at >10(-5)M decreased the expression of μ-OPR, but not δ- or κ-OPRs.

CONCLUSION

Generalized cytokine suppression along with downregulation of μ-OPR expression observed in neonatal MNC exposed to morphine and methadone at clinically relevant concentrations contrast with the modest effects observed with fentanyl and clonidine. Therefore, we speculate that fentanyl and clonidine may be safer therapeutic choices for sedation and control of opioid withdrawal and pain in neonates.

Treatment with unfractionated heparin attenuates coagulation and inflammation in endotoxemic mice

INTRODUCTION

In the pathogenesis of sepsis, inflammation and coagulation play a pivotal role. In addition to the anticoagulant activity, unfractionated heparin (UFH) has important immunomodulatory properties. However, different studies have reported conflicting effects on sepsis in association with heparin. The objective of this study is to determine whether UFH is able to reduce endotoxin-induced inflammation and coagulation in mice or produce improved outcome.

METHODS

C57BL/6J mice were randomly divided into two groups. Experimental mice were given intravenous injection of 8 units/20 g body weight UFH (heparin sodium) diluted in 20 μl sterile saline while the control mice received vehicle sterile saline only. They were injected with LPS (30 mg/kg, i.p.) 0.5h later. Blood was collected and Livers were harvested at 3 and 6h for analysis. In survival studies, a separate group of mice were treated with 8 units/20 g UFH (n=20) or sterile saline (n=20) given intravenously at 1, 12, 24 and 36 hours after LPS injection. Mice were monitored every 12 hours for a maximum of 72 hrs.

RESULTS

1) Pretreatment of mice with UFH strongly reduced the levels of TNF-α, IL-1β and TAT in plasma at 3 and 6h; 2) Pretreatment of mice with UFH inhibited the expression of TNF-α, IL-1β and tissue factor genes in blood cells at 3h; 3) UFH pretreatment dramatically diminished LPS-induced neutrophil sequestration (at 3 and 6h) , thrombi formation and fibrin(ogen) deposition in the liver (at 6h). 4) The UFH-pretreated group exhibited significantly lower levels of ALT and CRE at 6h. 5) Treatment with UFH could prevent mortality associated with endotoxin challenge.

CONCLUSION

These data suggest that UFH attenuates inflammation and coagulation and prevents lethality in endotoxemic mice.

Neuroprotection during cardiac surgery

Cardiac surgery continues to be associated with significant adverse cerebral outcomes, ranging from stroke to cognitive decline. The underlying mechanism of the associated cerebral injury is incompletely understood but is believed to be primarily caused by cerebral embolism and hypoperfusion, exacerbated by ischemia/reperfusion injury. Extensive research has been undertaken in an attempt to minimize the incidence of perioperative cerebral injury, and both pharmacological and nonpharmacological strategies have been investigated. Although many agents demonstrated promise in preclinical studies, there is currently insufficient evidence from clinical trials to recommend the routine administration of any pharmacological agents for neuroprotection during cardiac surgery. The nonpharmacological strategies that can be recommended on the basis of evidence include transesophageal echocardiography and epiaortic ultrasound-guided assessment of the atheromatous ascending aorta with appropriate modification of cannulation, clamping or anastomotic technique and optimal temperature management. Large-scale randomized controlled trials are still required to address further the issues of optimal pH management, glycemic control, blood pressure management and hematocrit during cardiopulmonary bypass. Past, present and future directions in the field of neuroprotection in cardiac surgery will be discussed.

Neuroprotection during cardiac surgery

Cerebral injury following cardiac surgery continues to be a significant source of morbidity and mortality after cardiac surgery. A spectrum of injuries ranging from subtle neurocognitive dysfunction to fatal strokes are caused by a complex series of multifactorial mechanisms. Protecting the brain from these injuries has focused on intervening on each of the various etiologic factors. Although numerous studies have focused on a pharmacologic solution, more success has been found with nonpharmacologic strategies, including optimal temperature management and reducing emboli generation.

Shock and hemorrhage: an overview of animal models

Shock resulting from life-threatening blood loss (hemorrhage) remains a common complication of traumatic injury. Intensive experimental efforts are needed if we are to understand the pathological effect(s) of hemorrhagic shock, alone or in association with traumatic tissue injury, and to reverse this deleterious process in trauma patients. Here, we overview selected studies that are representative of the different hemorrhagic shock models, considering their advantages and disadvantages from a scientific and clinical perspective. Fixed-pressure versus fixed-volume versus uncontrolled hemorrhage models, with or without tissue injury, will be discussed, as well as small versus large animal models. Most of these models are nonlethal in nature, and allow the researcher to understand the changes that contribute to increased susceptibility to subsequent infection or the development of multiple organ failure. We also consider some of the confounders in these models, including anesthesia, the nature of resuscitation, and the use of anticoagulants. The selection of model must take into consideration not only the need for experimental control but must also adequately reflect the clinical pathobiology of shock if we are to develop better pharmacological interventions.

Heparin binds to lipopolysaccharide (LPS)-binding protein, facilitates the transfer of LPS to CD14, and enhances LPS-induced activation of peripheral blood monocytes

Heparin is one of the most effective drugs for preventing and treating thromboembolic complications in surgical patients. Recent evidence suggests that heparin enhances the proinflammatory responses of human peripheral blood monocytes to Gram-negative endotoxin (LPS). We have identified LPS-binding protein (LBP) as a novel heparin-binding plasma protein. The affinity of LPB to heparin was KD = 55 +/- 8 nM, as measured by surface plasmon resonance. Using a fluorescence-based assay, we showed that clinically used heparin preparations significantly enhance the ability of LBP to catalytically disaggregate and transfer LPS to CD14, the LPS receptor. The presence of clinically relevant heparin concentrations in human whole blood increased LPS-induced production of the proinflammatory cytokine IL-8. Fondaparinux, which is identical with the antithrombin III-binding pentasaccharide in heparin, did not bind to LBP or alter LBP function. Thus, this novel anticoagulant drug is a potential candidate for safe administration to patients who have endotoxemia and require anticoagulation.

Influence of low molecular weight heparin (certoparin) and unfractionated heparin on the release of cytokines from human leukocytes

We analyzed the influence of heparins (unfractionated heparin, UFH and low molecular weight heparin certoparin) on the generation of IL-1ra, IL-6, IL-10, and IL-12p40 and from leukocyte fractions in vitro. Polymorphonuclear neutrophil leukocytes (PMN) and peripheral blood mononuclear cells (PBMC) from 16 different healthy donors were isolated and adjusted to 1 x 10(6) cells/ml supplemented RPMI 1640. Leukocyte fractions were differentially stimulated (PMN with 1 microg and 5 microg LPS, PBMC with 10 ng TSST- 1 or 2 microg ConA) in the presence or absence of heparins (1 U/ml, 2 U/ml, and 4 U/ml) for 24 h at 37 degrees C. Cytokine release was analyzed by ELISA. Certoparin but not UFH led to a dose-dependent increase in IL-6 from non-stimulated PBMC. In contrast, the release of IL-1ra, IL-10, and IL-12p40 was not modulated by heparins in a dose-dependent fashion. Increases in these cytokines occurred only as single incidents at intermediate heparin levels. An influence of the heparins on the apoptosis of PMN (measured as DNA-fragmentation in non-stimulated or LPS-stimulated cell-fractions) was not observed.

Cardiopulmonary bypass elicits a pro- and anti-inflammatory cytokine response and impaired neutrophil chemotaxis in neonatal pigs

BACKGROUND

Cardiopulmonary bypass (CPB) induces a systemic inflammatory response and organ dysfunction, especially in children. Plasma concentration of inflammatory markers are increased in response to the trauma of cardiac surgery and CPB. The aim of the present study was to investigate whether the CPB procedure in itself elicits increased levels of inflammatory markers in neonatal pigs.

METHODS

The inflammatory response was measured in piglets undergoing sternotomy alone (sham group, n=13) or sternotomy and CPB (n=14). Inflammatory mediators were measured at baseline and at fixed time-points during and after CPB. IL-8, IL-10 and TNF-alpha levels and C-reactive protein (CRP) concentrations were measured in plasma samples. Polymorphonuclear neutrophils (PMN) chemotaxis was measured ex vivo, and CD-18 expression using an immunofluorescence technique.

RESULTS

Immediately after the CPB procedure increased IL-8 levels were found in the CPB group, but not in sham operated animals (P=0.005). Simultaneously, a marked IL-10 response was measured in the CPB group. Concurrently, PMN chemotaxis decreased in CPB animals but not in the sham group (P=0.04). CD-18 expression and CRP levels were not significantly different between groups and TNF-alpha showed no changes in either group. The chemotactic response did not correlate with plasma IL-8 or IL-10, nor with CD-18 expression.

CONCLUSION

The CPB procedure elicited a systemic inflammatory response in terms of significantly elevated plasma levels of IL-8 and IL-10. Furthermore, a temporary and simultaneous decrease in PMN chemotaxis was observed immediately after CPB.

Apoptosis of peripheral blood lymphocytes is induced by catecholamines

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

The effect of propofol on human gastric and colonic muscle contractions

Although propofol is widely used for sedation in the intensive care unit, there are limited data on its effects on gastrointestinal motility. For that reason, we studied the in vitro effects of propofol on human gastric and colonic smooth muscle. Grossly normal human gastric and colonic muscle strips were mounted in an organ bath set-up for isometric contraction and stimulated by acetylcholine (Ach), using a cumulative dose schedule in the absence or presence of different concentrations of propofol [1.7 x 10(-6) M (0.3 microg/mL) to 4.4 x 10(-4) M (78 microg/mL)]. Ach led to concentration-dependent contraction of both gastric and colonic muscle strips, whereas propofol, at a concentration 6.7 x 10(-6) M (1.2 microg/mL) and above, significantly depressed Ach-induced contraction in a concentration-dependent manner for both smooth muscle preparations. In addition, propofol, at a concentration 2.7 x 10(-5)M (4.8 microg/mL) and above, depressed spontaneous contractile activity of both smooth muscle preparations. Fat emulsion 10% (Intralipid), the solvent for propofol, had no effect on either the spontaneous activity or the Ach-induced contraction of gastric and colonic smooth muscles.

IMPLICATIONS

The success of enteral feeding requires a normal gastrointestinal motility. We found that, at clinically relevant concentrations, propofol impaired gastrointestinal contractile activity. Further investigations are required to determine the clinical significance of this change.

Intramucosal acidosis and the inflammatory response in acute pancreatitis

OBJECTIVE

The aim of this study was to assess the host response and diminished bowel perfusion during acute pancreatitis.

METHODS

A total of 19 patients admitted with established diagnoses of acute pancreatitis on the basis of clinical findings, elevated serum amylase to more than four times the upper limit or by contrast radiology. Patients were stratified into mild and severe pancreatitis using the Atlanta criteria. Blood samples were obtained from in-dwelling lines or direct venipuncture within 12 h of admission and 24 hourly thereafter for measurements of plasma endotoxin, EndoCab immunoglobulin (Ig)G and IgM antibodies, tumor necrosis factor (TNF), p55 TNF receptor, and IL-6. A gastric tonometer was inserted in place of a nasogastric tube for intramucosal pH evaluation.

RESULTS

Episodes of endotoxaemia were more common and endotoxin concentration significantly higher at presentation in the severe group compared to the mild group of patients. A greater consumption of IgM antibody was found in those with severe disease. The decrease in IgM antibody concentration was shown to be a specific host response, as a fall in concentration of antibodies to a neutral antigen, tetanus toxoid, was not observed. Significantly greater elevations were found in p55 TNF receptor and IL-6 concentrations in the severe group in comparison to those suffering mild pancreatitis. Significant correlations were found between gastric intramucosal pH and EndoCab IgM antibody, p55 TNF receptor, and IL-6.

CONCLUSIONS

These results suggest that endotoxemia, an acute inflammatory response, and a reduction in bowel perfusion may occur in severe acute pancreatitis. The endotoxemia and inflammatory response may be due to the permeation of bacteria and their breakdown products across a disrupted bowel mucosal barrier.

Perioperative cytokine release during coronary artery bypass grafting in patients of different ages

Surgical interventions and cardiopulmonary bypass (CPB) induce a systemic inflammatory response with cytokine release. Ageing is perceived as a process of impaired immune functions: IL-1beta, IL-6 and tumour necrosis factor-alpha (TNF-alpha) secretion are increased while IL-2 release is reduced in advanced age. At present, little information is available about perioperative immune reactions at different stages of ageing. The aim of the present study was to compare IL-6, IL-1beta, TNF-alpha, IL-10 and soluble IL-2 receptor (sIL-2R) in younger and older patients undergoing cardiac surgery. Male patients (n = 14) undergoing elective coronary artery bypass grafting (CABG) surgery employing CPB with moderate hypothermia were divided into two groups according to their age: group 1 included seven patients < 50 years old, group 2 included seven patients > 65 years old. All patients received general anaesthesia using a balanced technique with sufentanil, isoflurane and midazolam. Blood samples were collected pre-operatively (T1); intra-operatively during CPB (T2); post-operatively on the day of surgery (T3); on the first post-operative day (T4). Blood concentrations of IL-6, IL-1beta, IL-10, TNF-alpha and sIL-2R were measured using commercially available ELISA kits and corrected for plasma cell volume. Statistical analysis was performed by non-parametric analysis of variance and Mann-Whitney U-test. Significance level was set to P<0.05. There were no statistically significant differences in the perioperative release of TNF-alpha, IL-6, IL-1beta, IL-10 and sIL-2R among the two groups. We conclude that the perioperative course of cytokine release in patients undergoing CABG surgery with CPB and comparable perioperative management does not significantly differ in the two age groups.

Enhanced spontaneous antibody response after coronary artery bypass surgery

PURPOSE

Cells spontaneously secreting immunoglobulins can be seen in the blood one week after open-heart surgery. The purpose of this study was to measure the antibody specificities of activated cells.

METHODS

Immune responses were studied preoperatively and on the seventh postoperative day in 18 patients undergoing elective coronary artery bypass surgery. The number of cells secreting adenovirus, measles, rubella and tetanus antigen specific antibodies spontaneously and induced by pokeweed mitogen PWM (ASCs) as well as the total number of cells secreting IgG, IgM and IgA (ISCs) were studied using an enzyme-linked immunospot (ELISPOT) assay. Spontaneous as well as phytohaemagglutinin (PHA)- and pokeweed mitogen (PWM)-induced lymphocyte proliferation was also measured.

RESULTS

The number of cells spontaneously secreting IgG, IgM and IgA antibodies was increased on the seventh day after coronary bypass surgery, against adenovirus, measles, rubella and tetanus as well as the total number of cells secreting immunoglobulins IgG, IgM and IgA (P < 0.05/0.001). By contrast, only slight fluctuation was seen in the numbers of cells secreting antibodies after PWM stimulation. Spontaneous lymphocyte proliferation was also increased, PHA proliferative responses were depressed and PWM responses were not changed on the seventh postoperative day compared with preoperative values.

CONCLUSION

Coronary artery bypass surgery caused marked polyclonal B cell activation demonstrated by an increase of cells producing spontaneously antibodies against virus antigens and tetanus toxoid. This activation could not be intensified by PWM stimulation.