Hyperbaric oxygenation improve red blood cell deformability in patients with acute or chronic inflammation.

INTRODUCTION: Red blood cells (RBC) are one of the key elements of the microcirculation. Their ability to pass through capillaries and to deliver oxygen to cells is due to their large degree of deformability linked to the characteristics of the RBC membrane. Alterations in RBC deformability as a result of membrane damage, linked in part to increased synthesis of reactive oxygen species (ROS), can be observed in several diseases, such as sepsis, and may contribute to the altered microcirculation observed in these pathologies. Hyperbaric oxygen therapy (HBOT), with inhalation of 100 % oxygen, has been proposed in several acute or chronic pathologies, including carbon monoxide poisoning. OBJECTIVE: We investigated the effects of HBOT on oxidative stress from ROS produced by myeloperoxidase (MPO) and on RBC deformability in patients with acute or chronic inflammation (n = 10), in patients with acute carbon monoxide poisoning (n = 10), and in healthy volunteers (n = 10). METHODS: RBC deformability was evaluated before and after HBOT in the various populations using the ektacytometry technique (Laser-assisted Optical Rotational Red Cell Analyzer - LORRCA). Deformability was determined by the elongation index (EI) in relation to the shear stress (SS) over a range of 0.3 to 50 Pa. Oxidative stress was estimated through changes in proteins (chlorotyrosine and homocitrulline) induced by MPO activity measured by liquid chromatography-tandem mass spectrometry analysis. RESULTS: Before HBOT, EI was significantly lower in patients with acute or chronic inflammation than in healthy volunteers and patients with acute carbon monoxide poisoning for the majority of SS values studied. After one session of HBOT, the EI was significantly higher than before HBOT for SS values of 1.93 Pa or higher in patients with acute or chronic inflammation. This effect remains constant after 10 sessions. There were no differences before and after HBOT in protein or amino acid oxidation due to ROS generation mediated by MPO in the three populations. CONCLUSIONS: Our results confirm altered RBC deformability in patients with acute and chronic conditions associated with an underlying inflammatory process. HBOT improves deformability only after one session and therefore may improve microcirculation in this population. According to our results, this improvement does not seem mediated by the ROS pathway via MPO. These results need to be confirmed in a larger population.

Effects of red blood cell transfusion on global oxygenation in anemic critically ill patients.

BACKGROUND: Consensus for transfusion in intensive care unit (ICU) patients recommends a restrictive strategy, based on a hemoglobin (Hb) concentration of 7 g/dL. Red blood cell (RBC) transfusion is used to prevent tissue hypoxia by improving oxygen transport (DO2 ) and therefore oxygen consumption (VO2 ). We studied the effects of RBC transfusion on systemic oxygenation parameters reflecting systemic oxygen extraction (EO2 = DO2 /VO2 ): S(c)vO2 , lactate level, venous-to-arterial carbon dioxide difference (Pv-aCO2 ), and cardiac index/EO2 (CI/EO2 ) and evaluated their usefulness in guiding transfusion decisions in ICU patients. STUDY DESIGN AND METHODS: Prospectively, all adult patients transfused were included except those with active bleeding or without a jugular or subclavian catheter. We measured O2 parameters before and after transfusion. Patients were a priori grouped according to their initial S(c)vO2 (< or ≥70%), treatment with vasopressors, cardiac function, and septic status. RESULTS: A total of 62 patients received 105 RBC transfusions. For all, mean arterial pressure (77 [69-88] to 81 [73-91] mm Hg), Hb concentration (7.4 [7.0-7.8] to 8.4 [7.7-8.9] g/dL) and S(c)vO2 (65% [59%-73%] to 69% [62%-75%]) increased after transfusion (all P < .001). S(c)vO2 improved after transfusion only when initial S(c)vO2 was less than 70% (62% [56%-65%] to 66% [61%-71%]; P < .001). In this group, Pv-aCO2 , lactate concentrations, and CI/EO2 did not change after transfusion. Cardiac function, sepsis, or vasopressor therapy did not affect these results. CONCLUSIONS: Among systemic O2 parameters, only a S(c)vO2 < 70% in anemic ICU patients improves after transfusion. As S(c)vO2 can reflect a DO2 /VO2 imbalance, it could be helpful when combined with the Hb concentration to decide whether to transfuse. However, the benefit on outcome should be further studied.

Myeloperoxidase promotes tube formation, triggers ERK1/2 and Akt pathways and is expressed endogenously in endothelial cells.

Myeloperoxidase is a member of the mammalian peroxidase family, mainly expressed in the myeloblastic cell lineage. It is considered a major bactericidal agent as it is released in the phagosome where it catalyzes the formation of reactive oxygen species. It is also released in the extracellular spaces including blood where it is absorbed on (lipo)proteins and endothelial cell surface, interfering with endothelial function. We performed RNA sequencing on MPO-treated endothelial cells, analyzed their transcriptome and validated the profile of gene expression by individual qRT-PCR. Some of the induced genes could be grouped in several functional networks, including tubulogenesis, angiogenesis, and blood vessel morphogenesis and development as well as signal transduction pathways associated to these mechanisms. MPO treatment mimicked the effects of VEGF on several signal transduction pathways, such as Akt, ERK or FAK involved in angiogenesis. Accordingly MPO, independently of its enzymatic activity, stimulated tube formation by endothelial cells. RNA interference also pointed at a role of endogenous MPO in tubulogenesis and endothelium wound repair in vitro. These data suggest that MPO, whether from endogenous or exogenous sources, could play a role in angiogenesis and vascular repair in vivo.

Predictive value of the RIFLE urine output criteria on contrast-induced nephropathy in critically ill patients.

BACKGROUND: To investigate the predictive value of decreased urine output based on the Risk of renal dysfunction, Injury to the kidney, Failure of kidney function, Loss of kidney function and End-stage renal disease (RIFLE) classification on contrast- induced acute kidney injury (CA-AKI) in intensive care (ICU) patients. METHODS: All patients who received contrast media (CM) injection for CT scan or coronary angiography during a 3-year period in a 24 bed medico-surgical ICU were reviewed. RESULTS: Daily serum creatinine concentrations and diuresis were measured for 3 days after CM injection. We identified 23 cases of CA-AKI in the 149 patients included (15.4 %). Patients who developed CA-AKI were more likely to require renal replacement therapy and had higher ICU mortality rates. At least one RIFLE urine output criteria was observed in 45 patients (30.2 %) and 14 of these 45 patients (31.1 %) developed CA-AKI based on creatinine concentrations. In 30 % of these cases, urine output decreased or didn't change after the increase in creatinine concentrations. The RIFLE urine output criteria had low sensitivity (39.1 %) and specificity (67.9 %) for prediction of CA-AKI, a low positive predictive value of 50 % and a negative predictive value of 87.2 %. The maximal dose of vasopressors before CM was the only independent predictive factor for CA-AKI. CONCLUSIONS: CA-AKI is a frequent pathology observed in ICU patients and is associated with increased need for renal replacement therapy and increased mortality. The predictive value of RIFLE urine output criteria for the development of CA-AKI based on creatinine concentrations was low, which limits its use for assessing the effects of therapeutic interventions on the development and progression of AKI.

Comparison of dopamine and norepinephrine in the treatment of shock.

BACKGROUND: Both dopamine and norepinephrine are recommended as first-line vasopressor agents in the treatment of shock. There is a continuing controversy about whether one agent is superior to the other. METHODS: In this multicenter, randomized trial, we assigned patients with shock to receive either dopamine or norepinephrine as first-line vasopressor therapy to restore and maintain blood pressure. When blood pressure could not be maintained with a dose of 20 microg per kilogram of body weight per minute for dopamine or a dose of 0.19 microg per kilogram per minute for norepinephrine, open-label norepinephrine, epinephrine, or vasopressin could be added. The primary outcome was the rate of death at 28 days after randomization; secondary end points included the number of days without need for organ support and the occurrence of adverse events. RESULTS: The trial included 1679 patients, of whom 858 were assigned to dopamine and 821 to norepinephrine. The baseline characteristics of the groups were similar. There was no significant between-group difference in the rate of death at 28 days (52.5% in the dopamine group and 48.5% in the norepinephrine group; odds ratio with dopamine, 1.17; 95% confidence interval, 0.97 to 1.42; P=0.10). However, there were more arrhythmic events among the patients treated with dopamine than among those treated with norepinephrine (207 events [24.1%] vs. 102 events [12.4%], P<0.001). A subgroup analysis showed that dopamine, as compared with norepinephrine, was associated with an increased rate of death at 28 days among the 280 patients with cardiogenic shock but not among the 1044 patients with septic shock or the 263 with hypovolemic shock (P=0.03 for cardiogenic shock, P=0.19 for septic shock, and P=0.84 for hypovolemic shock, in Kaplan-Meier analyses). CONCLUSIONS: Although there was no significant difference in the rate of death between patients with shock who were treated with dopamine as the first-line vasopressor agent and those who were treated with norepinephrine, the use of dopamine was associated with a greater number of adverse events. (ClinicalTrials.gov number, NCT00314704.)

Serum Metabolomic Profiles in Critically Ill Patients with Shock on Admission to the Intensive Care Unit.

Inflammatory processes are common in intensive care (ICU) patients and can induce multiple changes in metabolism, leading to increased risks of morbidity and mortality. Metabolomics enables these modifications to be studied and identifies a patient's metabolic profile. The objective is to precise if the use of metabolomics at ICU admission can help in prognostication. This is a prospective ex-vivo study, realized in a university laboratory and a medico-surgical ICU. Metabolic profiles were analyzed by proton nuclear magnetic resonance. Using multivariable analysis, we compared metabolic profiles of volunteers and ICU patients divided into predefined subgroups: sepsis, septic shock, other shock and ICU controls. We also assessed possible correlations between metabolites and mortality. One hundred and eleven patients were included within 24 h of ICU admission, and 19 healthy volunteers. The ICU mortality rate was 15%. Metabolic profiles were different in ICU patients compared to healthy volunteers (p < 0.001). Among the ICU patients, only the subgroup of patients with septic shock had significant differences compared to the ICU control patients in several metabolites: pyruvate, lactate, carnitine, phenylalanine, urea, creatine, creatinine and myo-inositol. However, there was no correlation between these metabolite profiles and mortality. On the first day of ICU admission, we observed changes in some metabolic products in patients with septic shock, suggesting increased anaerobic glycolysis, proteolysis, lipolysis and gluconeogenesis. These changes were not correlated with prognosis.

Treatment of the syndrome of inappropriate secretion of antidiuretic hormone with urea in critically ill patients.

BACKGROUND: Hyponatremia occurring as a result of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a common and potentially lethal complication in critically ill patients. Urea, by inducing renal water excretion and promoting sodium (Na) retention, has been well described as a treatment for chronic SIADH. However, there are limited data on its use for the treatment of SIADH as encountered in patients admitted to the intensive care unit (ICU). We assessed the effects of urea administration for treatment of SIADH in ICU patients. METHODS: Data from ICU patients treated with urea for SIADH between January 2000 and August 2010 were reviewed. The time courses of Na and urea concentrations were analyzed by variance analysis (ANOVA). RESULTS: Records from 24 patients were analyzed. The most common etiology of SIADH was neurological (18 patients). Before urea administration, the mean serum Na concentration was 124.8 ± 5.9 mEq/l. There was a significant increase in serum Na from the second day of treatment (131.4 ± 3.5 mEq/l, p < 0.001) and a normalization of mean serum Na by the fourth day (136.2 ± 4.1 mEq/l, p < 0.001). The mean serum urea concentration also increased (from 29.8 ± 11.1 mg/dl before urea to 57.6 ± 24.0 mg/dl on the first day of treatment, p < 0.001). CONCLUSIONS: Urea administration appears useful for the treatment of SIADH-associated hyponatremia in critically ill patients. Prospective randomized controlled studies are needed to confirm these results.

Effects of Preconditioning on RBC Deformability in Critically Ill Patients.

RBCs from critically ill patients have depressed deformability, especially in sepsis. Prolonged exposure of RBCs from healthy volunteers to physiologic shear stress (the preconditioning technique) has been associated with improved deformability, but the effect of preconditioning on RBCs from critically ill patients with or without sepsis has never been studied. DESIGN: Prospective study. SETTING: A 32-bed medico-surgical ICU and a university-affiliated cell biology laboratory. SUBJECTS: RBCs from 26 healthy volunteers and 40 critically ill patients (20 with and 20 without sepsis). INTERVENTIONS: RBC deformability was measured using the elongation index (EI) with an ektacytometer, at shear stress levels ranging from 0.3 to 50 Pa. To assess the effects of preconditioning in the three groups, we measured EI after first applying a shear stress of 5 Pa for 300 seconds. To study the potential mechanisms involved in preconditioning, we looked at deformability after incubation of an RBC solution from the healthy volunteers with glutaraldehyde, a membrane-stabilizing protein, and neuraminidase, an enzyme that releases membrane sialic acid. MEASUREMENTS AND MAIN RESULTS: Baseline RBC deformability was significantly depressed in the septic patients compared with the volunteers at all shear stress levels greater than or equal to 4.89 Pa. Preconditioning improved deformability only in the volunteers (at shear stress levels of 0.48 and 0.76 Pa). Among the critically ill patients, preconditioning worsened RBC deformability at higher shear stress levels. After incubation (with glutaraldehyde or neuraminidase) of RBCs from five volunteers in whom preconditioning had significantly improved deformability, the positive effect of preconditioning was lost with glutaraldehyde. CONCLUSIONS: RBC deformability is depressed in septic patients. There was a deleterious effect of preconditioning on RBC deformability in septic patients, unlike the positive effect on RBCs from healthy volunteers. The effect of preconditioning may be associated with elasticity of the cell membrane.

Red Blood Cell Shape and Deformability in Patients With COVID-19 Acute Respiratory Distress Syndrome.

Background: Acute respiratory distress syndrome due to coronavirus disease 2019 (COVID-19) is associated with high mortality. Several studies have reported that the microcirculation responds adequately to hypoxia in COVID-19 patients by increasing oxygen availability, in contrast to the inadequate response observed in patients with bacterial sepsis. Red blood cells (RBCs), the key cells for oxygen transport, and notably their rheology, are altered during bacterial sepsis, but few data are available in patients with COVID-19. Methods: In this prospective, non-interventional study, shape was assessed on admission (or inclusion for the volunteers) using Pearson's second coefficient of dissymmetry (PCD) on the histogram obtained with a flow cytometer technique. A null value represents a perfect spherical shape. RBC deformability was determined using ektacytometry by the elongation index in relation to the shear stress (0.3 to 50 Pa) applied to the RBC membrane. A higher elongation index indicates greater RBC deformability. Results were compared across groups. Scanning electronic microscopy was performed on RBCs from COVID-19 patients. RBC shape and deformability were also assessed on days 3 and 7 in COVID-19 patients. Results: Forty-nine ICU patients were included (30 with COVID-19 ARDS and 19 with bacterial sepsis). ARDS was more severe in patients with COVID-19 than in those with sepsis (PaO2/FiO2 99 [73-154] vs. 270 [239-295] mmHg p < 0.001) and mechanical ventilation was more frequently required (87 vs. 21%; p < 0.001). Mortality was significantly higher in COVID-19 patients (15/30 [50%] vs. 4/19 [21%], p = 0.046). RBCs were significantly more spherical in septic patients (PCD -0.40 [-0.56; -0.18]) than in healthy volunteers (PCD -0.54 [-0.66; -0.49]) but not than in COVID-19 patients (-0.48 [-0.55; -0.43]). In COVID-19 non-survivors (n = 11), sphericity was more marked on day 7 (PCD -0.40 [-0.47; -0.28]) than on day 1 (PCD vs. -0.49 [-0.59; -0.44]); p = 0.045. At ICU admission, RBC deformability was altered for all shear stress values studied in septic patients compared to COVID-19 patients and healthy volunteers (maximum elongation index for septic patients: 0.600 [0.594-0.630] vs. 0.646 [0.637-0.653] for COVID-19 patients and 0.640 [0.635-0.650] for healthy volunteers; both p < 0.001). In the 18 COVID-19 patients studied for 7 days, RBC deformability did not change over time and was not related to outcome. At day 1, RBCs from COVID-19 patients showed a normal structure on scanning electronic microscopy. Conclusion: In contrast to the significantly altered shape and decreased deformability in patients with bacterial sepsis, RBCs from severely hypoxemic COVID-19 patients had normal deformability on admission, and this pattern did not change over the first week despite a more spherical shape in non-survivors. As RBCs are the key cell for oxygen transport, this maintenance of normal deformability may contribute to the adequate microcirculatory response to severe hypoxia of the microcirculation that has been observed in these patients.

Evolution of red blood cell membrane complement regulatory proteins and rheology in septic patients: An exploratory study.

Background: During sepsis, red blood cell (RBC) deformability is altered. Persistence of these alterations is associated with poor outcome. Activation of the complement system is enhanced during sepsis and RBCs are protected by membrane surface proteins like CD35, CD55 and CD59. In malaria characterized by severe anemia, a study reported links between the modifications of the expression of these RBCs membrane proteins and erythrophagocytosis. We studied the evolution of RBCs deformability and the expression of RBC membrane surface IgG and regulatory proteins in septic patients. Methods: By flow cytometry technics, we measured at ICU admission and at day 3-5, the RBC membrane expression of IgG and complement proteins (CD35, 55, 59) in septic patients compared to RBCs from healthy volunteers. Results were expressed in percentage of RBCs positive for the protein. RBC shape was assessed using Pearson's second coefficient of dissymmetry (PCD) on the histogram obtained with a flow cytometer technique. A null value represents a perfect spherical shape. RBC deformability was determined using ektacytometry by the elongation index in relation to the shear stress (0.3-50 Pa) applied to the RBC membrane. A higher elongation index indicates greater RBC deformability. Results: RBCs from 11 septic patients were compared to RBCs from 21 volunteers. At ICU admission, RBCs from septic patients were significantly more spherical and RBC deformability was significantly lower in septic patients for all shear stress ≥1.93 Pa. These alterations of shape and deformability persists at day 3-5. We observed a significant decrease at ICU admission only in CD35 expression on RBCs from septic patients. This low expression remained at day 3-5. Conclusions: We observed in RBCs from septic patients a rapid decrease expression of CD35 membrane protein protecting against complement activation. These modifications associated with altered RBC deformability and shape could facilitate erythrophagocytosis, contributing to anemia observed in sepsis. Other studies with a large number of patients and assessment of erythrophagocytosis were needed to confirm these preliminary data.

Thromboprophylaxis in Critically Ill Coronavirus Disease 2019 Patients.

It is now reported that coronavirus disease 2019 ICU patients are at increased risk of thrombosis. Expert opinion and scientific societies recommend a higher dose of low-molecular-weight heparin, but definitive data is lacking. We report our adapted thromboprophylaxis practice of low-molecular-weight heparin administration in coronavirus disease 2019 ICU patients. One-hundred six measurements in 19 ICU patients were collected. Despite enoxaparin 60 mg once daily, only two measurements of the trough anti-Xa were in the upper end of prophylactic range. Anti-Xa activity peaks increased significantly after administration, but all measurements were under the optimal prophylactic ranges. Despite an adapted protocol, three of the 19 patients (16%) developed venous thromboembolism. We show in coronavirus disease 2019 ICU patients, despite higher prophylactic low-molecular-weight heparin administration due to body mass index, anti-Xa activity was well below peak serum levels in our cohort of critically ill coronavirus disease 2019 patients. This evaluation suggests the need for rapid studies on adequate thromboprophylaxis in these patients.

Plasma fibrinolysis is related to the degree of organ dysfunction but not to the concentration of von Willebrand Factor in critically ill patients.

BACKGROUND: Endothelial cell dysfunction, by promoting fibrin deposition, has been implicated in the development of multiple organ failure. Altered fibrinolysis during inflammation may participate in microvascular alterations. We sought to determine whether plasma fibrinolysis was related to the severity of organ dysfunction and/or to the levels of von Willebrand factor (vWF antigen), as a marker of endothelium dysfunction, in critically ill patients. METHODS: Forty-nine consecutive patients admitted to an adult medico-surgical intensive care unit (ICU) with (18) or without sepsis (31) were included. C-reactive protein and vWF levels were measured on ICU admission and plasma fibrinolysis was assessed by the Euglobulin Clot Lysis Time (ECLT). The sequential organ failure assessment (SOFA) score and the simplified acute physiology score (SAPS) II were calculated on admission. RESULTS: ECLT was significantly longer in septic than in non-septic patients [1033 min (871-1372) versus 665 min (551-862), p = 0.001]. There were significant correlations between ECLT and C-reactive protein (CRP) concentrations (r = 0.78, p < 0.001) and the Sequential Organ Failure Assessment (SOFA) score (r = 0.39, p = 0.006). The level of vWF was not correlated with the ECLT (r = -0.06, p = 0.65) or the SOFA score (r = -0.02, p = 0.88). CONCLUSION: ECLT measurement at admission could be a marker of organ dysfunction and a prognostic indicator in critically ill patients.

Apoliporotein L3 interferes with endothelial tube formation via regulation of ERK1/2, FAK and Akt signaling pathway.

BACKGROUND AND AIMS: Endothelial cells are main actors in vascular homeostasis as they regulate vascular pressure and permeability as well as hemostasis and inflammation. Disturbed stimuli delivered to and by endothelial cells correlate with the so-called endothelial dysfunction and disrupt this homeostasis. As constituents of the inner layer of blood vessels, endothelial cells are also involved in angiogenesis. Apolipoprotein Ls (APOL) comprise a family of newly discovered apolipoproteins with yet poorly understood function, and are suggested to be involved in inflammatory processes and cell death mechanisms. Here we investigate the role of APOLs in endothelial cells stimulated with factors known to be involved in atherogenesis and their possible contribution to endothelial dysfunction with an emphasis on inflammation driven-angiogenesis in vitro. METHODS: Using the CRISPR/Cas9 technique, we analyzed the effect of APOL3 gene knock out in HMEC-1 endothelial cells on cell migration, tubulogenesis, endothelial permeability, intracellular signal transduction as assessed by kinase phosphorylation, and angiogenesis gene expression (measured by qRT-PCR). RESULTS: Our results indicate that among the family, APOL3 was the only member induced by myeloperoxidase, oxidized LDL, VEGF and FGF treatments. APOL3 invalidation increased endothelial permeability, reduced wound repair and tubule formation in vitro, the latter only in MPO and VEGF-induced conditions. Accordingly, some pro-angiogenic signaling pathways (ERK1/2 and FAK but not Akt) and some pro-angiogenic genes were partially inhibited in APOL3 knock out cells. CONCLUSIONS: These findings suggest the involvement of APOL3 in angiogenesis in vitro and as a modulator of MAPK and FAK signaling in endothelial cells.

Predictive value of C-reactive protein in critically ill patients after abdominal surgery.

OBJECTIVES:: The development of sepsis after abdominal surgery is associated with high morbidity and mortality. Due to inflammation, it may be difficult to diagnose infection when it occurs, but measurement of C-reactive protein could facilitate this diagnosis. In the present study, we evaluated the predictive value and time course of C-reactive protein in relation to outcome in patients admitted to the intensive care unit (ICU) after abdominal surgery. METHODS:: We included patients admitted to the ICU after abdominal surgery over a period of two years. The patients were divided into two groups according to their outcome: favorable (F; left the ICU alive, without modification of the antibiotic regimen) and unfavorable (D; death in the ICU, surgical revision with or without modification of the antibiotic regimen or just modification of the regimen). We then compared the highest C-reactive protein level on the first day of admission between the two groups. RESULTS:: A total of 308 patients were included: 86 patients had an unfavorable outcome (group D) and 222 had a favorable outcome (group F). The groups were similar in terms of leukocytosis, neutrophilia, and platelet count. C-reactive protein was significantly higher at admission in group D and was the best predictor of an unfavorable outcome, with a sensitivity of 74% and a specificity of 72% for a threshold of 41 mg/L. No changes in C-reactive protein, as assessed based on the delta C-reactive protein, especially at days 4 and 5, were associated with a poor prognosis. CONCLUSIONS:: A C-reactive protein cut-off of 41 mg/L during the first day of ICU admission after abdominal surgery was a predictor of an adverse outcome. However, no changes in the C-reactive protein concentration, especially by day 4 or 5, could identify patients at risk of death.

Time Course of CD64, a Leukocyte Activation Marker, During Cardiopulmonary Bypass Surgery.

Distinction between inflammation secondary to surgery, especially coronary artery bypass graft with cardiopulmonary bypass (CPB), and inflammation due to infection is difficult in surgical intensive care unit (ICU) patients. Development of biomarkers of infection could help clinicians in the early identification and thus treatment of sepsis in these patients. We compared the time course of the neutrophil CD64 index, a high affinity immunoglobulin FC γ receptor I whose expression is increased in bacterial infection, in 39 patients undergoing cardiac surgery with CPB and 11 patients admitted to the ICU with severe sepsis or septic shock. The CD64 index was significantly more elevated in septic patients than in patients who had CPB except at day 5. The CD64 index increased moderately on day 1 after cardiac surgery but the value remained lower than in septic patients. The duration for which the CD64 index was greater than 1.0 was longer in septic than in CPB patients. Receiver operating curves to differentiate CPB from sepsis on day 1 were not significantly different between C-reactive protein (CRP) concentrations and CD 64 index. Nevertheless, combination of low CD64 index with low CRP concentrations on day 1 ruled out sepsis except in three patients. There were no correlations between the CD64 index and cytokine levels (tumor necrosis factor [TNF]-α, interferon [IFN]γ, interleukin [IL]-6, IL-10, IL-8, IL-12) measured in subpopulations. In conclusion, CD64 index only in combination with CRP concentrations could be used to discriminate inflammation due to surgery from that due to infection in this particular population.

Apolipoprotein L Expression Correlates with Neutrophil Cell Death in Critically Ill Patients.

Delayed neutrophil apoptosis has been demonstrated in sepsis and may contribute to organ damage. It has recently been proposed that apolipoprotein L (ApoL) may be involved in programmed cell death, but the expression and functions of ApoLs in leukocytes (especially neutrophils) during sepsis and other inflammatory conditions are currently unknown. In this prospective observational study in a 36-bed university hospital medicosurgical intensive care unit (ICU), we included 78 adult ICU patients with (n = 41) or without (n = 37) sepsis and 47 healthy volunteers. We analyzed ApoL mRNA expression using quantitative polymerase chain reaction in whole blood leukocytes and protein expression in CD15 isolated neutrophils using Western blotting. Neutrophil apoptosis was assessed using the APO-BRDU method. Apolipoprotein L mRNA was downregulated in whole blood leukocytes and neutrophils in ICU patients compared with in healthy volunteers, and this effect translated at the protein level as indicated by Western blot analysis of neutrophils. There was a negative correlation between ApoL expression in neutrophils and C-reactive protein levels and a positive correlation between the number of apoptotic neutrophils and mRNA levels of ApoL1 and ApoL2. The degree of neutrophil apoptosis in critically ill patients is therefore correlated with modified expression profiles of ApoLs.

Leukocyte phosphodiesterase expression after lipopolysaccharide and during sepsis and its relationship with HLA-DR expression.

Phosphodiesterases (PDEs) may modulate inflammatory pathways, but PDE expression is poorly documented in humans with sepsis. Using quantitative PCR on whole blood leukocytes, we characterized PDE mRNA expression in healthy volunteers (n = 20), healthy volunteers given lipopolysaccharide (LPS; n = 18), and critically ill patients with (n = 20) and without (n = 20) sepsis. PDE4B protein expression was also studied in magnetic-activated cell sorting (MACS)-isolated CD15+ neutrophils (from 7 healthy volunteers, 5 patients without and 5 with sepsis). We studied relationships between PDE expression, HLA-DR (mRNA and expression on CD14+ monocytes), tumor necrosis factor (TNF)-α, and interleukin (IL)-10 levels. LPS administration in volunteers was associated with increases in PDE4B and PDE4D and decreases in PDE4A and PDE7A mRNAs. The observed global down-regulation of the HLA-DR complex was correlated with PDE7A. Critically ill patients had lower TNF-α/IL-10 mRNA ratios than the volunteers had and global down-regulation of the HLA-DR complex. Septic patients had persistently lower mRNA levels of PDE7A, PDE4A, and 4B (also at a protein level) and decreasing levels of PDE4D over time. Low PDE4D mRNA levels correlated negatively with HLA-DMA and HLA-DMB. LPS administration and sepsis are, therefore, associated with different PDE mRNA expression patterns. The effect of PDE changes on immune dysfunction and HLA-DR expression requires further investigation.