Leukocyte Activation Patterns in Hospitalized Children: Comparing SARS-CoV-2, Bacterial Infections, and Inflammatory Pathologies.

In adults, monocytes and neutrophils play important roles in the hyper-inflammatory responses' characteristic of severe forms of SARS-CoV-2 infection. We assessed leukocyte activation in 55 children attending the emergency department for acute fever between March 2020 and September 2021. The following markers were analyzed by flow cytometry: CD169 and HLA-DR on monocytes, CD64 and CD16 on neutrophils, CD38 on lymphocytes TCD8. Fifteen of the children had SARS-CoV-2 infection, 15 had bacterial infections, 15 had inflammatory diseases. We observed overexpression of CD169 on monocytes and CD38 on lymphocytes T in all patients with a diagnosis of SARS-CoV-2, while overexpression of CD64 on neutrophils was observed with bacterial infections and inflammatory diseases. There was a decrease in the expression of HLA-DR on monocytes in the bacterial infection and inflammatory pathology groups. Leukocyte analysis identifies distinct activation patterns in children during SARS-CoV-2 infections, bacterial infections, and inflammatory diseases.

Is Personalized Dietary Therapy Effective for Individuals With Irritable Bowel Syndrome?

Introduction: Adverse reactions to foods and food additives have a critical role in clinical manifestations of irritable bowel syndrome (IBS). Personalized dietary modifications conducted under the supervision of a qualified health practitioner could considerably impact the clinical care and course of the condition. Objective: To investigate the clinical effectiveness of the Lifestyle Eating and Performance (LEAP) program based on the Leukocyte Activation Assay-MRT (LAA-MRT®) results in improving IBS symptoms and quality of life. Methods: The retrospective study included de-identified client records (n = 146) from private group practices seen by registered dietitians. The eligibility criteria were adults aged > 18 years old with an established diagnosis of IBS. Results: Participants were 46.7 ± 12.6 years old and had a BMI of 26.7 ± 6.1 kg/m2; the majority were female (87.0%) and followed-up by a registered dietitian for 10.1 ± 6.4 weeks. There was a significant reduction post-dietary intervention in overall Global Gastrointestinal Symptom Survey Scores (P < 0.001) and improvement in quality of life (P < 0.001). Conclusion: This study generates real-world evidence of an alternative treatment option for IBS using a personalized dietary approach. A more precise understanding of the effect of food intake reactions is vital for clinical improvements and enhancing health outcomes in IBS.

The evaluation of constant coronary artery flow versus constant coronary perfusion pressure during normothermic ex situ heart perfusion.

BACKGROUND: Evidence suggests that hearts that are perfused under ex-situ conditions lose normal coronary vasomotor tone and experience contractile failure over a few hours. We aimed to evaluate the effect of different coronary perfusion strategies during ex situ heart perfusion on cardiac function and coronary vascular tone. METHODS: Porcine hearts (n = 6 each group) were perfused in working mode for 6 hours with either constant aortic diastolic pressure (40 mmHg) or constant coronary flow rate (500 mL/min). Functional and metabolic parameters, cytokine profiles, cardiac and vascular injury, coronary artery function and oxidative stress were compared between groups. RESULTS: Constant coronary flow perfusion demonstrated better functional preservation and less edema formation (Cardiac index: flow control = 8.33 vs pressure control = 6.46 mL·min-1·g-1, p = 0.016; edema formation: 7.92% vs 19.80%, p < 0.0001). Pro-inflammatory cytokines, platelet activation as well as endothelial activation were lower in the flow control group. Similarly, less cardiac and endothelial injury was observed in the constant coronary flow group. Evaluation of coronary artery function showed there was loss of coronary autoregulation in both groups. Oxidative stress was induced in the coronary arteries and was relatively lower in the flow control group. CONCLUSIONS: A strategy of controlled coronary flow during ex situ heart perfusion provides superior functional preservation and less edema formation, together with less myocardial damage, leukocyte, platelet, endothelial activation, and oxidative stress. There was loss of coronary autoregulation and decrease of coronary vascular resistance during ESHP irrespective of coronary flow control strategy. Inflammation and oxidative stress state in the coronary vasculature may play a role.

SARS-CoV-2 triggers complement activation through interactions with heparan sulfate.

Objectives: To determine whether SARS-CoV-2 can trigger complement activation, the pathways that are involved and the functional significance of the resultant effect. Methods: SARS-CoV-2 was inoculated into a human lepirudin-anticoagulated whole blood model, which contains a full repertoire of complement factors and leukocytes that express complement receptors. Complement activation was determined by measuring C5a production with an ELISA, and pretreatment with specific inhibitors was used to identify the pathways involved. The functional significance of this was then assessed by measuring markers of C5a signalling including leukocyte C5aR1 internalisation and CD11b upregulation with flow cytometry. Results: SARS-CoV-2 inoculation in this whole blood model caused progressive C5a production over 24 h, which was significantly reduced by inhibitors for factor B, C3, C5 and heparan sulfate. However, this phenomenon could not be replicated in cell-free plasma, highlighting the requirement for cell surface interactions with heparan sulfate. Functional analysis of this phenomenon revealed that C5aR1 signalling and CD11b upregulation in granulocytes and monocytes was delayed and only occurred after 24 h. Conclusion: SARS-CoV-2 is a noncanonical alternative pathway activator that progressively triggers complement activation through interactions with heparan sulfate.

The Role of Biodegradable Poly-(L-lactide)-Based Polymers in Blood Cell Activation and Platelet-Monocyte Interaction.

The main purpose of new stent technologies is to overcome unfavorable material-related incompatibilities by producing bio- and hemo-compatible polymers with anti-inflammatory and anti-thrombogenic properties. In this context, wettability is an important surface property, which has a major impact on the biological response of blood cells. However, the influence of local hemodynamic changes also influences blood cell activation. Therefore, we investigated biodegradable polymers with different wettability to identify possible aspects for a better prediction of blood compatibility. We applied shear rates of 100 s-1 and 1500 s-1 and assessed platelet and monocyte activation as well as the formation of CD62P+ monocyte-bound platelets via flow cytometry. Aggregation of circulating platelets induced by collagen was assessed by light transmission aggregometry. Via live cell imaging, leukocytes were tracked on biomaterial surfaces to assess their average velocity. Monocyte adhesion on biomaterials was determined by fluorescence microscopy. In response to low shear rates of 100 s-1, activation of circulating platelets and monocytes as well as the formation of CD62P+ monocyte-bound platelets corresponded to the wettability of the underlying material with the most favorable conditions on more hydrophilic surfaces. Under high shear rates, however, blood compatibility cannot only be predicted by the concept of wettability. We assume that the mechanisms of blood cell-polymer interactions do not allow for a rule-of-thumb prediction of the blood compatibility of a material, which makes extensive in vitro testing mandatory.

Selenocompounds and Sepsis: Redox Bypass Hypothesis for Early Diagnosis and Treatment: Part A-Early Acute Phase of Sepsis: An Extraordinary Redox Situation (Leukocyte/Endothelium Interaction Leading to Endothelial Damage).

Significance: Sepsis is a health disaster. In sepsis, an initial, beneficial local immune response against infection evolves rapidly into a generalized, dysregulated response or a state of chaos, leading to multiple organ failure. Use of life-sustaining supportive therapies creates an unnatural condition, enabling the complex cascades of the sepsis response to develop in patients who would otherwise die. Multiple attempts to control sepsis at an early stage have been unsuccessful. Recent Advances: Major events in early sepsis include activation and binding of leukocytes and endothelial cells in the microcirculation, damage of the endothelial surface layer (ESL), and a decrease in the plasma concentration of the antioxidant enzyme, selenoprotein-P. These events induce an increase in intracellular redox potential and lymphocyte apoptosis, whereas apoptosis is delayed in monocytes and neutrophils. They also induce endothelial mitochondrial and cell damage. Critical Issues: Neutrophil production increases dramatically, and aggressive immature forms are released. Leukocyte cross talk with other leukocytes and with damaged endothelial cells amplifies the inflammatory response. The release of large quantities of reactive oxygen, halogen, and nitrogen species as a result of the leukocyte respiratory burst, endothelial mitochondrial damage, and ischemia/reperfusion processes, along with the marked decrease in selenoprotein-P concentrations, leads to peroxynitrite damage of the ESL, reducing flow and damaging the endothelial barrier. Future Directions: Endothelial barrier damage by activated leukocytes is a time-sensitive event in sepsis, occurring within hours and representing the first step toward organ failure and death. Reducing or stopping this event is necessary before irreversible damage occurs.

Lack of early platelet and leukocyte activation can indicate complications after major burn injury.

BACKGROUND: Major burn injury causes massive tissue destruction consequently enhanced platelet function and leukocyte-mediated inflammatory response. METHODS: In a prospective, observational study 23 consecutive patients with more than 20% body surface burn injury were followed for five days (T1-T5) after admission to a university intensive care (ICU). Platelet and leukocyte antisedimentation rate (PAR and LAR) was measured by one-hour gravity sedimentation. It detects the percentage of total platelet and leukocyte number crossed the half line of blood sample column, therefore, they can be regarded as cells of decreased specific gravity. We aimed to investigate the time course of PAR and LAR after burn injury, as the trend of platelet and the leukocyte activation in the early post-burn period. RESULTS: Daily mean PAR and LAR values continuously increased in the observation period (T1 to T5). Daily mean PAR and LAR were lower in ICU non-survivors (n = 7) compared to survivors (n = 16) between T2 and T4 (p < 0.05 and p < 0.01). PAR values of septic patients (n = 10) were lower than that of non-septic ones (n = 13, p < 0.01 at T5). CONCLUSIONS: Both PAR and LAR, as novel bedside test can predict septic complications and unfavorable outcome after major burn injury. Further studies with higher sample size are warranted.

The blood compatibility challenge. Part 3: Material associated activation of blood cascades and cells.

Following protein adsorption/activation which is the first step after the contact of material surfaces and whole blood (part 2), fibrinogen is converted to fibrin and platelets become activated and assembled in the form of a thrombus. This thrombus formation is the key feature that needs to be minimized in the creation of materials with low thrombogenicity. Further aspects of blood compatibility that are important on their own are complement and leukocyte activation which are also important drivers of thrombus formation. Hence this review summarizes the state of knowledge on all of these cascades and cells and their interactions. For each cascade or cell type, the chapter distinguishes statements which are in widespread agreement from statements where there is less of a consensus. STATEMENT OF SIGNIFICANCE: This paper is part 3 of a series of 4 reviews discussing the problem of biomaterial associated thrombogenicity. The objective was to highlight features of broad agreement and provide commentary on those aspects of the problem that were subject to dispute. We hope that future investigators will update these reviews as new scholarship resolves the uncertainties of today.

Systemic Inflammation in Metabolic Syndrome: Increased Platelet and Leukocyte Activation, and Key Role of CX3CL1/CX3CR1 and CCL2/CCR2 Axes in Arterial Platelet-Proinflammatory Monocyte Adhesion.

BACKGROUND: Metabolic syndrome is associated with low-grade systemic inflammation, which is a key driver of premature atherosclerosis. We characterized immune cell behavior in metabolic syndrome, its consequences, and the potential involvement of the CX3CL1/CX3CR1 and CCL2/CCR2 chemokine axes. METHODS: Whole blood from 18 patients with metabolic syndrome and 21 age-matched controls was analyzed by flow cytometry to determine the leukocyte immunophenotypes, activation, platelet-leukocyte aggregates, and CX3CR1 expression. ELISA determined the plasma marker levels. Platelet-leukocyte aggregates adhesion to tumor necrosis factor-α (TNFα)-stimulated arterial endothelium and the role of CX3CL1/CX3CR1 and CCL2/CCR2 axes was investigated with the parallel-plate flow chamber. RESULTS: When compared with the controls, the metabolic syndrome patients presented greater percentages of eosinophils, CD3+ T lymphocytes, Mon2/Mon3 monocytes, platelet-eosinophil and -lymphocyte aggregates, activated platelets, neutrophils, eosinophils, monocytes, and CD8+ T cells, but lower percentages of Mon1 monocytes. Patients had increased circulating interleukin-8 (IL-8) and TNFα levels and decreased IL-4. CX3CR1 up-regulation in platelet-Mon1 monocyte aggregates in metabolic syndrome patients led to increased CX3CR1/CCR2-dependent platelet-Mon1 monocyte adhesion to dysfunctional arterial endothelium. CONCLUSION: We provide evidence of generalized immune activation in metabolic syndrome. Additionally, CX3CL1/CX3CR1 or CCL2/CCR2 axes are potential candidates for therapeutic intervention in cardiovascular disorders in metabolic syndrome patients, as their blockade impairs the augmented arterial platelet-Mon1 monocyte aggregate adhesiveness, which is a key event in atherogenesis.

The dual functionality of antimicrobial peptides Os and Os-C in human leukocytes.

Antimicrobial peptides (AMPs), Os and Os-C, have been identified as multifunctional peptides with antibacterial, antiendotoxin, and anti-inflammatory properties. For further development of Os and Os-C as therapeutic peptides, it is essential to evaluate these effects in human mononuclear (MN) and polymorphonuclear (PMN) leukocytes. The cytotoxicity and the effects of both peptides on MN and PMN morphology were determined with the Alamar-Blue assay and scanning electron microscopy, respectively. The ability of Os and Os-C to induce reactive oxygen species (ROS) and to protect against 2,2'-azobis(2-amidinopropane) dihydrochloride-induced oxidative damage in both cell populations was evaluated using 2',7'-dichlorofluorescin diacetate (DCFH-DA). Using fluorescently labeled peptides, the ability of the peptides to cross the cell membranes of MN and PMN was also evaluated. At the minimum bactericidal concentrations of Os and Os-C, neither peptide was cytotoxic. Os caused morphological features of toxicity at 100 µM, entered MN cells, and also protected these cells against oxidative damage. Os-C caused MN and PMN leukocyte activation associated with ROS formation and was unable to penetrate cell membranes, indicating extracellular membrane interactions. This study confirms that both Os and Os-C at less than 100 µM are not cytotoxic. The MN-specific uptake of Os identifies it as a cell-specific cargo-carrier peptide, with additional anti-inflammatory properties. In contrast, the ability of Os-C to activate MN and PMN cells implies that this peptide should be further evaluated as an AMP, which, in addition to its ability to eradicate infection, can further enhance host immunity. These novel characteristics of Os and Os-C indicate that these AMPs as peptides can be further developed for specific applications.

Novel Immune Features of the Systemic Inflammation Associated with Primary Hypercholesterolemia: Changes in Cytokine/Chemokine Profile, Increased Platelet and Leukocyte Activation.

Primary hypercholesterolemia (PH) is associated with a low grade systemic inflammation that is likely the main driver of premature atherosclerosis. Accordingly, we characterized the immune cell behaviour in PH and its potential consequences. Whole blood from 22 PH patients and 21 age-matched controls was analysed by flow cytometry to determine the percentage of leukocyte immunophenotypes, activation, and platelet-leukocyte aggregates. Plasma markers were determined by Enzyme-Linked ImmunoSorbent Assay (ELISA). The adhesion of platelet-leukocyte aggregates to tumor necrosis factor-α (TNFα)-stimulated arterial endothelium was investigated using the dynamic model of the parallel-plate flow chamber. PH patients presented greater percentage of Mon 3 monocytes, Th2 and Th17 lymphocytes, activated platelets, and leukocytes than controls. The higher percentages of circulating platelet-neutrophil, monocyte and lymphocyte aggregates in patients caused increased platelet-leukocyte adhesion to dysfunctional arterial endothelium. Circulating CXCL8, CCL2, CX3CL1, and IL-6 levels positively correlated with key lipid features of PH, whereas negative correlations were found for IL-4 and IL-10. We provide the first evidence that increased platelet and leukocyte activation leads to elevated platelet-leukocyte aggregates in PH and augmented arterial leukocyte adhesiveness, a key event in atherogenesis. Accordingly, modulation of immune system behavior might be a powerful target in the control of further cardiovascular disease in PH.

Low-stress Microfluidic Density-gradient Centrifugation for Blood Cell Sorting.

Density gradient centrifugation exploits density differences between different blood cells to accomplish separation of peripheral blood mononuclear cells (PBMCs) from polymorphonuclear (PNM) cells, and erythrocytes or red blood cells (RBCs). While density gradient centrifugation offers a label-free alternative avoiding the use of harsh lysis buffers for blood cell isolation, it is a time-consuming and labor-intensive process during which blood cells are subject to high-levels of centrifugal force that can artifactually activate cells. To provide a low-stress alternative to this elegant method, we miniaturized and automated this process using microfluidics to ensure continuous PBMCs isolation from whole blood while avoiding the exposure to high-levels of centrifugal stress in a simple flow-through format. Within this device, a density gradient is established by exploiting laminar flow within microfluidic channels to layer a thin stream of blood over a larger stream of Ficoll. Using this approach we demonstrate successful isolation of PBMCs from whole blood with preservation of monocytes and different lymphocyte subpopulations similar to that seen with conventional density gradient centrifugation. Evaluation of activation status of PBMCs isolated using this technique shows that our approach achieves minimal isolation process induced activation of cells in comparison to conventional lysis or density gradient centrifugation. This simple, automated microfluidic density gradient centrifugation technique can potentially serve as tool for rapid and activation-free technique for isolation of PBMCs from whole blood for point-of-care applications.

A leukocyte activation test identifies food items which induce release of DNA by innate immune peripheral blood leucocytes.

BACKGROUND: Leukocyte activation (LA) testing identifies food items that induce a patient specific cellular response in the immune system, and has recently been shown in a randomized double blinded prospective study to reduce symptoms in patients with irritable bowel syndrome (IBS). We hypothesized that test reactivity to particular food items, and the systemic immune response initiated by these food items, is due to the release of cellular DNA from blood immune cells. METHODS: We tested this by quantifying total DNA concentration in the cellular supernatant of immune cells exposed to positive and negative foods from 20 healthy volunteers. To establish if the DNA release by positive samples is a specific phenomenon, we quantified myeloperoxidase (MPO) in cellular supernatants. We further assessed if a particular immune cell population (neutrophils, eosinophils, and basophils) was activated by the positive food items by flow cytometry analysis. To identify the signaling pathways that are required for DNA release we tested if specific inhibitors of key signaling pathways could block DNA release. RESULTS: Foods with a positive LA test result gave a higher supernatant DNA content when compared to foods with a negative result. This was specific as MPO levels were not increased by foods with a positive LA test. Protein kinase C (PKC) inhibitors resulted in inhibition of positive food stimulated DNA release. Positive foods resulted in CD63 levels greater than negative foods in eosinophils in 76.5% of tests. CONCLUSION: LA test identifies food items that result in release of DNA and activation of peripheral blood innate immune cells in a PKC dependent manner, suggesting that this LA test identifies food items that result in release of inflammatory markers and activation of innate immune cells. This may be the basis for the improvement in symptoms in IBS patients who followed an LA test guided diet.

Thrombosis in Philadelphia negative classical myeloproliferative neoplasms: a narrative review on epidemiology, risk assessment, and pathophysiologic mechanisms.

Thrombosis is common in cancer patients and is associated with increased morbidity and mortality. Myeloproliferative neoplasms (MPN) are common malignancies in elderly individuals and are known for a high incidence of thrombotic complications. Different risk factors have been identified in studies, and risk models have been developed to identify patients with MPN at higher risk for thrombosis. Several pathophysiological mechanisms help explain the increased likelihood of thrombosis in these patients. Factors, such as leukocyte and platelet activation leading to the formation of leukocyte-platelet aggregates, activation of the coagulation cascade by microparticles, high levels of inflammatory cytokines, and endothelial dysfunction have a crucial role in thrombosis in MPN patients. Recent studies have demonstrated a significant association between the allele burden of specific genetic mutations (mainly JAK2V617F) associated with MPN and the incidence of thrombotic events, thus suggesting a possible role for these mutations in thrombogenesis.

Myeloid-related protein-8/14 in acute coronary syndrome.

BACKGROUND: The alarmin family member myeloid-related protein (MRP)-14 (S100A9), which has been identified by platelet transcriptional profiling as an acute myocardial infarction gene, regulates vascular inflammation and thrombosis. Elevated plasma levels of MRP-8/14 (S100A8/A9) heterodimer predict first and recurrent cardiovascular events. The aim of this study was to elucidate pathophysiological roles of MRP-8/14 in acute coronary syndrome (ACS). METHODS AND RESULTS: In 38 consecutive ACS patients, the MRP-8/14 level in coronary artery blood obtained at thrombus aspiration was higher in 23 patients, in whom aspirated thrombus was confirmed, compared to the 15 patients, in whom it was absent [4.86 (1.95, 8.29) vs 2.94 (1.31, 4.44), P=0.017]. The MRP-8/14 level was correlated with myeloperoxidase (MPO) level (R2=0.52), but not with soluble P-selectin level (R2=0.0002) in the coronary artery blood. Immunohistochemistry of the aspirated thrombus exhibited that expression of MRP8/14 was co-localized with leukocytes positive for activated Mac-1. Finally, in cultured human umbilical vein endothelial cells, MRP-8/14 increased tissue factor expression. CONCLUSIONS: Our findings indicate that MRP-8/14 concentration increases in coronary artery blood in association with thrombus formation in ACS, co-localizes with leukocytes, and is associated with leukocyte activation. MRP-8/14 is positioned as a unique biomarker at the interface of inflammation and thrombosis in ACS.

Role for coronin 1 in mouse NK cell function.

Coronin 1, a member of the evolutionary conserved WD repeat protein family of coronin proteins is expressed in all leukocytes, but a role for coronin 1 in natural killer (NK) cell homeostasis and function remains unclear. Here, we have analyzed the number and functionality of NK cells in the presence and absence of coronin 1. In coronin 1-deficient mice, absolute NK cell numbers and phenotype were comparable to wild type mice in blood, spleen and liver. Following in vitro stimulation of the activating NK cell receptors NK1.1, NKp46, Ly49D and NKG2D, coronin 1-deficient NK cells were functional with respect to interferon-γ production, degranulation and intracellular Ca2+ mobilization. Also, both wild type as well as coronin 1-deficient NK cells showed comparable cytotoxic activity. Furthermore, activation and functionality of NK cells following Vesicular Stomatitis Virus (VSV) infection was similar between wild type and coronin 1-deficient mice. Taken together these data suggest that coronin 1 is dispensable for mouse NK cell homeostasis and function.

Water-soluble egg membrane enhances the immunoactivating properties of an Aloe vera-based extract of Nerium oleander leaves.

OBJECTIVE: To evaluate a blend of two natural ingredients on immune parameters relevant for their current topical use and potential support of microcirculation in skin tissue. MATERIALS AND METHODS: A blend (BL) of Aloe vera-based Nerium oleander extract (NAE-8i, oleandrin-free) and hydrolyzed water-soluble egg membrane (WSEM) was applied to human whole-blood cultures for 24 hours, with each separate ingredient serving as a control. Immune-cell subsets were analyzed for expression levels of the activation markers CD69 and CD25. Culture supernatants were analyzed for cytokines, chemokines, and immunoregulating peptides. RESULTS: BL increased CD69 expression on lymphocytes, monocytes, and CD3-CD56+ natural killer cells, and CD25 expression on natural killer cells. The number of CD69+CD25+ lymphocytes increased in cultures treated with BL and the separate ingredients. BL triggered production of multiple cytokines and chemokines, where CC chemokines MIP1α and MIP3α, as well as cytokines involved in wound healing - Groα, Groß, ENA78, and fractalkine - reached levels manyfold above treatment with either NAE-8i or WSEM alone. CONCLUSION: Data on BL showed that WSEM strongly enhanced NAE-8i's effects on immunoactivation in vitro. This has potential relevance for support of immunity in skin tissue, including antibacterial and antiviral defense mechanisms, wrinkle reduction, and wound care.

Systemic Inflammatory Response Syndrome in End-Stage Heart Failure Patients Following Continuous-Flow Left Ventricular Assist Device Implantation: Differences in Plasma Redox Status and Leukocyte Activation.

The role of oxidative stress and leukocyte activation has not been elucidated in developing systemic inflammatory response syndrome (SIRS) in heart failure (HF) patients after continuous-flow left ventricular assist device (CF-LVAD) implantation. The objective of this study was to investigate the change of plasma redox status and leukocyte activation in CF-LVAD implanted HF patients with or without SIRS. We recruited 31 CF-LVAD implanted HF patients (16 SIRS and 15 non-SIRS) and 11 healthy volunteers as the control. Pre- and postimplant blood samples were collected from the HF patients. Plasma levels of oxidized low-density lipoprotein (oxLDL), malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide dismutase (SOD) in erythrocyte, myeloperoxidase (MPO), and polymorphonuclear elastase (PMN-elastase) were measured. The HF patients had a preexisting condition of oxidative stress than healthy controls as evident from the higher oxLDL and MDA levels as well as depleted SOD and TAC. Leukocyte activation in terms of higher plasma MPO and PMN-elastase was also prominent in HF patients than controls. Persistent oxidative stress and reduced antioxidant status were found to be more belligerent in HF patients with SIRS after the implantation of CF-LVAD when compared with non-SIRS patients. Similar to oxidative stress, the activation of blood leukocyte was significantly highlighted in SIRS patients after implantation compared with non-SIRS. We identified that the plasma redox status and leukocyte activation became more prominent in CF-LVAD implanted HF patients who developed SIRS. Our findings suggest that plasma biomarkers of oxidative stress and leukocyte activation may be associated with the development of SIRS after CF-LVAD implant surgery.

Platelet serotonin modulates immune functions.

This short review addresses immune functions of platelet serotonin. Platelets transport serotonin at a high concentration in dense granules and release it upon activation. Besides haemostatic, vasotonic and developmental modulation, serotonin also influences a variety of immune functions (mediated by different serotonin receptors). First, platelet serotonergic effects are directed against invading pathogens via activation and proliferation of lymphocytes, modulation of cytokine release, and recruitment of neutrophils to sites of acute inflammation by induction of selectin expression on endothelial cells. Second, serotonin levels are elevated in autoimmune diseases, such as asthma or rheumatoid arthritis, and during tissue regeneration after ischemia of myocardium or brain. Specific antagonism of serotonin receptors appears to improve survival after myocardial infarction or sepsis and to attenuate asthmatic attacks in animal models. It will be of great clinical relevance if these findings can be translated into human applications. In conclusion, targeting immune modulatory effects of platelet serotonin may provide novel therapeutic options for common health problems.

In vivo evidence for chylomicrons as mediators of postprandial inflammation.

BACKGROUND AND AIMS: The postprandial situation is a pro-inflammatory condition most likely linked to the development of atherosclerosis. We evaluated the relationship between apolipoprotein (apo) B48 and fasting and postprandial leukocyte activation markers. METHODS: Leukocyte activation markers and apo B48 were determined in 80 subjects with and without coronary artery disease (CAD). Twelve healthy subjects underwent an oral fat loading test (up to 8 h). RESULTS: Fasting apo B48 was significantly higher in patients with CAD (n = 47, 8.1 ± 5.2 mg/L) than in subjects without CAD (n = 33, 5.9 ± 3.9 mg/L, p = 0.022). Fasting apo B48 and triglycerides correlated positively with fasting monocyte CD11b and neutrophil CD66b expression. Plasma apo B48 and leukocyte activation markers increased after an oral fat load. No correlations were found between fasting or postprandial triglycerides and postprandial leukocyte activation markers. We observed no correlations between postprandial apo B48 and postprandial neutrophil CD11b or CD66b expression. CONCLUSION: This study suggests that chylomicron remnants may be responsible for postprandial leukocyte activation in the circulation. The postprandial chylomicron response may be a stronger mediator of postprandial inflammation than postprandial triglyceridemia.