Inflammation, endothelium, and coagulation in sepsis

Coagulation disorders in patients with severe leptospirosis are associated with severe bleeding and mortality

OBJECTIVE

To determine the involvement of coagulation in bleeding and poor outcome in patients with severe leptospirosis.

METHODS

In a prospective study, parameters of the coagulation system were measured on admission and during follow-up in 52 consecutive patients with severe leptospirosis.

RESULTS

All patients showed coagulation disorders, such as prolonged prothrombin time (PT) and activated partial thromboplastin time, marked procoagulant activity [thrombin-antithrombin (TAT) complexes, prothrombin fragment 1+2, D-dimer], reduced levels of anticoagulant markers (protein C, antithrombin) and increased (anti-) fibrinolytic activity [plasmin-antiplasmin (PAP) complexes, plasminogen activator inhibitor-1]. These disorders were more pronounced in patients who died eventually. PT prolongation was associated with mortality (OR 1.4, 95% CI: 1.0-1.8, P = 0.04). Bleeding occurred in 31 subjects (60%). Of these, 24 had mild bleeding and seven had severe haemorrhages. Thrombocytopenia (platelets </=100 x 10(9)/l) was significantly associated with clinical bleeding (OR 4.6, 95% CI: 1.3-16). A subanalysis of patients with and without severe bleeding revealed a more pronounced imbalance of the coagulation system in patients with severe bleeding, as reflected by a significant association with PT (OR 1.4, 95% CI: 1.0-1.8, P = 0.05) and the TAT/PAP ratio (OR 1.3, 95% CI: 1.0-1.6, P = 0.05), which is an indicator of the balance between coagulation and fibrinolysis. Overt disseminated intravascular coagulation (DIC) was found in 10 (22%) of the 46 patients for whom the score could be calculated. There was no significant association between DIC scores, bleeding diathesis or poor outcome.

CONCLUSION

The coagulation system was strongly activated in patients with leptospirosis. This was more pronounced in the deceased and in patients with severe bleeding than in than the survivors and in those without severe bleeding.

The cell-based model of coagulation

OBJECTIVE

To review the current model describing coagulation processes, including the critical contributions of cells.

DATA SOURCES

Original research articles, scientific reviews, and textbooks.

DATA SYNTHESIS

Normal hemostasis is vital for prevention of blood loss, but controls are necessary to limit coagulation to the site of injury. The previous cascade model of blood coagulation, although refined and updated over the last few decades, is flawed as a description of how hemostasis occurs in vivo. The recently proposed model incorporates the vital role of cells in coagulation processes, and corrects deficiencies of the older cascade models.

CONCLUSIONS

The cell-based model of coagulation provides a description of coagulation that more likely reflects hemostatic processes as they occur in vivo.

Hemostasis and inflammation: two of a kind?

Hemostasis is a defense mechanism to stop bleeding. Activated by vessel wall injury, it consists of intertwined activation of platelets and the coagulation cascade, tightly controlled by natural anticoagulants and the fibrinolytic system.

Bench-to-bedside review: Beta-adrenergic modulation in sepsis

Sepsis, despite recent therapeutic progress, still carries unacceptably high mortality rates. The adrenergic system, a key modulator of organ function and cardiovascular homeostasis, could be an interesting new therapeutic target for septic shock. β-Adrenergic regulation of the immune function in sepsis is complex and is time dependent. However, β₂ activation as well as β₁ blockade seems to downregulate proinflammatory response by modulating the cytokine production profile. β₁ blockade improves cardiovascular homeostasis in septic animals, by lowering myocardial oxygen consumption without altering organ perfusion, and perhaps by restoring normal cardiovascular variability. β-Blockers could also be of interest in the systemic catabolic response to sepsis, as they oppose epinephrine which is known to promote hyperglycemia, lipid and protein catabolism. The role of β-blockers in coagulation is less clear cut. They could have a favorable role in the septic pro-coagulant state, as β₁ blockade may reduce platelet aggregation and normalize the depressed fibrinolytic status induced by adre-nergic stimulation. Therefore, β₁ blockade as well as β₂ activation improves sepsis-induced immune, cardiovascular and coagulation dysfunctions. β₂ blocking, however, seems beneficial in the metabolic field. Enough evidence has been accumulated in the literature to propose β- adrenergic modulation, β₁ blockade and β₂ activation in particular, as new promising therapeutic targets for septic dyshomeostasis, modulating favorably immune, cardiovascular, metabolic and coagulation systems.

Acute lung injury but not sepsis is associated with increased colony formation by peripheral blood mononuclear cells

Acute lung injury (ALI) and severe sepsis are common critical illnesses associated with the mobilization of bone marrow-derived cells into the circulation. By identifying and determining these cells' functional characteristics, unique prognostic biomarkers can be developed to help investigators understand the mechanisms underlying the pathophysiology of these disorders. We previously demonstrated an increased colony-forming unit (CFU) ability of circulating peripheral blood mononuclear cells (PBMCs) in patients with ALI, compared with healthy control subjects, that also correlated with improved survival. Here we hypothesized that the increased CFUs in ALI are associated with lung injury, and therefore ALI will result in an increased number of CFUs compared with patients exhibiting severe sepsis. To test this, blood was collected from 80 patients (63 with ALI, and 17 with severe sepsis) within 72 hours of diagnosis, and from 5 healthy control subjects. A CFU assay was performed on isolated PBMCs. Lung injury scores and the need for mechanical ventilation were greater in patients with ALI than in patients with severe sepsis (P < 0.0001 for each). CFU numbers were highest in patients with ALI compared with patients manifesting severe sepsis or control subjects (median CFU number [25-75% quartiles] of 61 [13-104] versus 17 [3-34] versus 5 [2-13], P < 0.0005). A trend toward improved survival was demonstrated in patients with high (> or = 48) CFUs (P = 0.06). No relationship between CFUs and mechanical ventilation was evident. Our findings suggest that increased colony-forming ability by PBMCs in ALI results from lung injury, independent of sepsis and mechanical ventilation. Factors contributing to colony formation by PBMCs in ALI, and the role PBMCs play in its pathogenesis remain to be fully established.

Lactobacillus casei modulates the inflammation-coagulation interaction in a pneumococcal pneumonia experimental model

Background

We have previously demonstrated that Lactobacillus casei CRL 431 administration improved the resistance to pneumococcal infection in a mouse model.

Methods

This study examined the effects of the oral administration of Lactobacillus casei CRL 431 (L. casei) on the activation of coagulation and fibrinolytic systems as well as their inhibitors during a Streptococcus pneumoniae infection in mice.

Results

The alveolo-capillary membrane was damaged and the coagulation system was also activated by the infection. As a consequence, we could see fibrin(ogen) deposits in lung histological slices, increased levels of thrombin-antithrombin complex (TATc) in bronchoalveolar lavage (BAL) and plasma, decrease in prothrombin activity (PT) and prolonged activated partial thromboplastin time test (APTT) values. Factor VII (FVII) and factor X (FX) were decreased in plasma, whereas fibrinogen (F) and factor VIII (FVIII) were increased. The low levels of protein C (PC) in BAL and plasma proved damage on inhibitory activity. The infected animals showed reduced fibrinolytic activity, evidenced by an increase in plasminogen activation inhibitor-1 (PAI-1) in BAL and plasma. The pathogen induced an increase of TNF-α, IL-1β and IL-6 in BAL and serum a few hours after challenge followed by a significant decrease until the end of the assayed period. IL-4 and IL-10 in BAL and serum were also augmented, especially at the end of the experiment. The animals treated with L. casei showed an improvement of alveolo-capillary membrane, lower fibrin(ogen) deposits in lung and decrease in TATc. APTT test and PT, FVII and FX activity were normalized. L. casei group showed lower F levels than control during whole experiment. In the present study no effect of L. casei on the recovery of the inhibitory activity was detected. However, L. casei was effective in reducing PAI-1 levels in BAL and in increasing anti-inflammatory ILs concentration.

Conclusion

L. casei proved effective to regulate coagulation activation and fibrinolysis inhibition during infection, leading to a decrease in fibrin deposits in lung. This protective effect of L. casei would be mediated by the induction of higher levels of IL-4 and IL-10 which could regulate the anti-inflammatory, procoagulant and antifibrinolytic effects of TNF-α, IL-1β and IL-6.

Human genetic deficiencies reveal the roles of complement in the inflammatory network: lessons from nature

Complement component C5 is crucial for experimental animal inflammatory tissue damage; however, its involvement in human inflammation is incompletely understood. The responses to gram-negative bacteria were here studied taking advantage of human genetic complement-deficiencies--nature's own knockouts--including a previously undescribed C5 defect. Such deficiencies provide a unique tool for investigating the biological role of proteins. The experimental conditions allowed cross-talk between the different inflammatory pathways using a whole blood model based on the anticoagulant lepirudin, which does not interfere with the complement system. Expression of tissue factor, cell adhesion molecules, and oxidative burst depended highly on C5, mediated through the activation product C5a, whereas granulocyte enzyme release relied mainly on C3 and was C5a-independent. Release of cytokines and chemokines was mediated to varying degrees by complement and CD14; for example, interleukin (IL)-1beta and IL-8 were more dependent on complement than IFN-gamma and IL-6, which were highly dependent on CD14. IL-1 receptor antagonist (IL-1ra) and IFN-gamma inducible protein 10 (IP-10) were fully dependent on CD14 and inversely regulated by complement, that is, complement deficiency and complement inhibition enhanced their release. Granulocyte responses were mainly complement-dependent, whereas monocyte responses were more dependent on CD14. Notably, all responses were abolished by combined neutralization of complement and CD14. The present study provides important insight into the comprehensive role of complement in human inflammatory responses to gram-negative bacteria.

Progress of tissue injury in appendicitis involves the serine proteases uPA and PAI-1

OBJECTIVE

Serine proteases and the matrix metalloproteinases (MMPs) are key factors in the proteolytic cascade and participate in extracellular matrix (ECM) degradation. Fibrinolytic activators and inhibitors may have an effect on inflammatory cells, thereby modulating the inflammatory response. It is reasonable to assume that they may be implicated in the tissue injury in acute appendicitis that subsequently leads to appendix perforation. The purpose of this study was to investigate the expression and distribution of urokinase-type plasminogen activator (uPA) and plasminogen-activator inhibitor type 1 (PAI-1) in appendicitis.

MATERIAL AND METHODS

Expression of uPA and expression of PAI-1 were measured in tissue specimens from patients with appendicitis (n=30) and in control specimens (n=9), using the quantitative ELISA technique. Distribution of enzymes was studied with immunohistochemistry. The uPA and PAI-1 levels in the subgroups of appendicitis and controls were compared.

RESULTS

The overall expressions of uPA and PAI-1 were greater in appendicitis than in control specimens (p <0.001 and p<0.0001, respectively). Expressions of uPA and PAI-1 in phlegmonous (n=15), gangrenous (n=6) and perforated appendicitis (n=9) were all higher than those in controls (n=9), (p<0.01). Moreover, the PAI-1 level was elevated in perforated appendicitis compared with phlegmonous appendicitis (p<0.01). uPA staining was observed in connection with vascular endothelial cells and the serosa stained intensely in specimens from perforated appendicitis.

CONCLUSIONS

The expression of uPA and especially the over-expression of PAI-1 seem to correlate to the progression of local inflammatory response in acute appendicitis.

Activation of endothelial intrinsic NF-{kappa}B pathway impairs protein C anticoagulation mechanism and promotes coagulation in endotoxemic mice

Although the role of systemic activation of the nuclear factor kappaB (NF-kappaB) pathway in septic coagulation has been well documented, little is known about the contribution of endothelial-specific NF-kappaB signaling in this pathologic process. Here, we used transgenic mice that conditionally overexpress a mutant I-kappaBalpha, an inhibitor of NF-kappaB, selectively on endothelium, and their wild-type littermates to define the role of endothelial-specific NF-kappaB in septic coagulation. In wild-type mice, lipopolysaccharide (LPS) challenge (5 mg/kg intraperitoneally) caused markedly increased plasma markers of coagulation, decreased plasma fibrinogen level, and widespread tissue fibrin deposition, which were abrogated by endothelial NF-kappaB blockade in transgenic mice. Endothelial NF-kappaB blockade inhibited tissue factor expression in endothelial cells, but not in leukocytes. Endothelial NF-kappaB blockade did not inhibit LPS-induced tissue factor expression in heart, kidney, and liver. Endothelial NF-kappaB blockade prevented LPS down-regulation of endothelial protein C receptor (EPCR) and thrombomodulin protein expressions, inhibited tissue tumor necrosis factor-alpha converting enzyme activity, reduced EPCR shedding, and restored plasma protein C level. Our data demonstrate that endothelial intrinsic NF-kappaB signaling plays a pivotal role in septic coagulation and suggests a link between endothelial-specific NF-kappaB activation and the impairment of the thrombomodulin-protein C-EPCR anticoagulation pathway.

Cell death serum biomarkers are early predictors for survival in severe septic patients with hepatic dysfunction

INTRODUCTION

Severe sepsis, septic shock, and resulting organ failure represent the most common cause of death in intensive care medicine, with mortality ranging from 40% to 70%. It is still unclear whether necrosis or apoptosis plays the predominant role in severe sepsis. Determining the prevalent mode of cell death would be valuable, as new therapeutic agents (eg, antiapoptotic drugs such as caspase inhibitors) may improve unsatisfactory outcomes in patients with severe sepsis. Furthermore, the prognostic value of newly developed cell death serum biomarkers is of great interest.

METHODS

In total, 147 patients (101 patients with severe sepsis, 28 postoperative patients after major abdominal surgery, 18 healthy volunteers) were enrolled. Baseline and clinical data were evaluated. Blood samples from patients with severe sepsis were collected at the time of sepsis diagnosis, and 48 and 120 hours later; samples from healthy volunteers were collected once, and from postoperative patients, once immediately after surgery. We measured caspase-cleaved and uncleaved cytokeratin-18 (CK-18, intermediate filament protein) as a marker of cell death, isolated CK-18 fragments as a marker of apoptosis, as well as IL-6, soluble vascular cell adhesion molecule, and soluble intercellular adhesion molecule.

RESULTS

Age and sex of patients with severe sepsis and postoperative patients were comparable, whereas healthy volunteers were significantly younger. In healthy volunteers, the mode of cellular turnover was primarily apoptotic cell death. Postoperative patients showed comparable levels of apoptotic activity, but necrotic cell death was markedly increased, probably due to surgical tissue injury. In contrast, patients with severe sepsis, and especially non-survivors of the septic group showed increased levels of markers for both apoptotic and necrotic cell death. In severe septic patients with liver dysfunction, necrosis is increased relative to severe septic patients with intact hepatic function. For severe septic patients with liver dysfunction, a cut-off value for caspase-cleaved and uncleaved cytokeratin-18 could be calculated, in order to identify patients at high risk for death due to severe sepsis.

CONCLUSIONS

The measurement of caspase-cleaved and uncleaved cytokeratin-18 appears to be an early predictor for survival in severe septic patients with hepatic dysfunction. Furthermore, the loss of parenchymal cells due to necrosis may be the primary mode of cell death in these patients. This may limit possible therapeutic options.

Essential role of cofilin-1 in regulating thrombin-induced RelA/p65 nuclear translocation and intercellular adhesion molecule 1 (ICAM-1) expression in endothelial cells

Activation of RhoA/Rho-associated kinase (ROCK) pathway and the associated changes in actin cytoskeleton induced by thrombin are crucial for activation of NF-kappaB and expression of its target gene ICAM-1 in endothelial cells. However, the events acting downstream of RhoA/ROCK to mediate these responses remain unclear. Here, we show a central role of cofilin-1, an actin-binding protein that promotes actin depolymerization, in linking RhoA/ROCK pathway to dynamic alterations in actin cytoskeleton that are necessary for activation of NF-kappaB and thereby expression of ICAM-1 in these cells. Stimulation of human umbilical vein endothelial cells with thrombin resulted in Ser(3) phosphorylation/inactivation of cofilin and formation of actin stress fibers in a ROCK-dependent manner. RNA interference knockdown of cofilin-1 stabilized the actin filaments and inhibited thrombin- and RhoA-induced NF-kappaB activity. Similarly, constitutively inactive mutant of cofilin-1 (Cof1-S3D), known to stabilize the actin cytoskeleton, inhibited NF-kappaB activity by thrombin. Overexpression of wild type cofilin-1 or constitutively active cofilin-1 mutant (Cof1-S3A), known to destabilize the actin cytoskeleton, also impaired thrombin-induced NF-kappaB activity. Additionally, depletion of cofilin-1 was associated with a marked reduction in ICAM-1 expression induced by thrombin. The effect of cofilin-1 depletion on NF-kappaB activity and ICAM-1 expression occurred downstream of IkappaBalpha degradation and was a result of impaired RelA/p65 nuclear translocation and consequently, RelA/p65 binding to DNA. Together, these data show that cofilin-1 occupies a central position in RhoA-actin pathway mediating nuclear translocation of RelA/p65 and expression of ICAM-1 in endothelial cells.

Protease-activated receptors as drug targets in inflammation and pain

Proteases have been shown to signal to cells through the activation of a novel class of receptors coupled to G proteins: the protease-activated receptors (PARs). Those receptors are expressed in a wide range of cells, which ultimately are all involved in mechanisms of inflammation and pain. Numerous studies have considered the role of PARs in cells, organ systems or in vivo, highlighting the fact that PAR activation results in signs of inflammation. A growing body of evidences discussed here suggests that these receptors, and the proteases that activate them, interfere with inflammation and pain processes. Whether a role for PARs has been clearly defined in inflammatory and pain pathologies is discussed in this review. Further, the pros and cons for considering PARs as targets for the development of therapeutic options for the treatment of inflammation and pain are discussed.

Sepsis and major abdominal surgery lead to flaking of the endothelial glycocalix

BACKGROUND

Recent evidence suggests that the endothelial glycocalix plays an important role in lethal outcomes following sepsis. We therefore tested if the endothelial glycocalix is shed in patients with sepsis compared with patients after major abdominal surgery and healthy volunteers.

MATERIAL AND METHODS

A total of 150 individuals were tested for levels of inflammatory markers (intercellular adhesion molecule-1 [ICAM-1], vascular cell adhesion molecule-1 [VCAM-1], interleukin-6 [IL-6]) and glycocalix markers (syndecan-1, heparan sulfate). Three groups consisted of patients with severe sepsis or septic shock, patients after major abdominal surgery without systemic inflammatory response syndrome, and healthy volunteers. Blood was drawn, at the time of diagnosis or surgery, and 6, 24, and 48h later. We correlated these markers to each other and to clinically used inflammation markers.

RESULTS

Levels of inflammatory markers were markedly higher in patients with sepsis compared with patients after major abdominal surgery and healthy volunteers. After major abdominal surgery, glycocalix markers in human plasma were at levels comparable to patients with sepsis. In patients with sepsis, levels of IL-6 correlated with syndecan-1, ICAM-1, VCAM-1, and lactate, while ICAM-1 furthermore correlated with CRP and lactate levels.

CONCLUSION

High levels of glycocalix markers indicated that significant flaking of the endothelial glycocalix occurred in patients with sepsis, and to a lesser extent in patients after major abdominal surgery. This novel finding could explain the nonspecific capillary leaking syndrome of patients with sepsis and after major abdominal surgery, and may identify new targets for treating those patient populations.

Disseminated intravascular coagulation in obstetric disorders and its acute haematological management

As activation of the coagulation pathway is a physiological response to injury, the development of disseminated intravascular coagulation (DIC) is a warning signal to the clinician that the primary pathological disease state is decompensating. In pregnancy, DIC can occur in several settings, which include emergencies such as placental abruption and amniotic fluid embolism as well as complications such as pre-eclampsia. Whilst the acuteness of the event and the proportionality in the coagulant and fibrinolytic responses may vary between these different conditions, a common theme for pregnancy-associated DIC is the pivotal role played by the placenta. Removal of the placenta is the linchpin to treatment in most cases but appropriate blood product support is also key to management. This is necessary because DIC itself can have pathological consequences that translate clinically into a worse prognosis for affected patients. This article will describe how pregnancy-associated DIC can be diagnosed promptly and how treatment should be managed strategically. It also discusses the latest developments in our understanding of haemostatic mechanisms within the placenta and how these may have relevance to new diagnostic approaches as well as novel therapeutic modalities.

Citrate anticoagulation for continuous venovenous hemofiltration

OBJECTIVE

Continuous venovenous hemofiltration (CVVH) is applied in critically ill patients with acute renal failure for renal replacement. Heparins used to prevent circuit clotting may cause bleeding. Regional anticoagulation with citrate reduces bleeding, but has metabolic risks. The aim was to compare the safety and efficacy of the two.

DESIGN

Randomized, nonblinded, controlled single-center trial.

SETTING

General intensive care unit of a teaching hospital.

PATIENTS

Adult critically ill patients needing CVVH for acute renal failure and without an increased bleeding risk.

INTERVENTIONS

Regional anticoagulation with citrate or systemic anticoagulation with the low-molecular weight heparin nadroparin.

MEASUREMENTS AND MAIN RESULTS

End points were adverse events necessitating discontinuation of study anticoagulant, transfusion, metabolic and clinical outcomes, and circuit survival. Of the 215 randomized patients, 200 received CVVH per protocol (97 citrate and 103 nadroparin). Adverse events required discontinuation of citrate in two patients (accumulation and clotting) of nadroparin in 20 (bleeding and thrombocytopenia) (p < 0.001). Bleeding occurred in 6 vs. 16 patients (p = 0.08). The median number of red blood cell units transfused per CVVH day was 0.27 (interquartile range, 0.0-0.63) for citrate, 0.36 (interquartile range, 0-0.83) for nadroparin (p = 0.31). Citrate conferred less metabolic alkalosis (p = 0.001) and lower plasma calcium (p < 0.001). Circuit survival was similar. Three-month mortality on intention-to-treat was 48% (citrate) and 63% (nadroparin) (p = 0.03), per protocol 45% and 62% (p = 0.02). Citrate reduced mortality in surgical patients (p = 0.007), sepsis (p = 0.01), higher Sepsis-Related Organ Failure Assessment score (p = 0.006), and lower age (p = 0.009).

CONCLUSIONS

The efficacy of citrate and nadroparin anticoagulation for CVVH was similar, however, citrate was safer. Unexpectedly, citrate reduced mortality. Less bleeding could only partly explain this benefit, less clotting could not. Post hoc citrate appeared particularly beneficial after surgery, in sepsis and severe multiple organ failure, suggesting interference with inflammation.

Prospective evaluation of coagulation in critically ill neonatal foals

BACKGROUND

Coagulopathy is a potentially underrecognized complication of sepsis and septic shock in critically ill neonatal foals.

HYPOTHESIS

Critically ill neonatal foals have abnormalities in coagulation that are associated with disease severity and outcome.

ANIMALS

Foals <72 hours old admitted to a neonatal intensive care unit.

METHODS

Prospective, observational study. Blood was collected at admission, 24, and 48 hours for platelet count, prothrombin time, activated partial thromboplastin time, antithrombin activity and concentrations of fibrin degradation products, and fibrinogen in plasma from all foals.

RESULTS

Sixty-three foals were enrolled and classified as Septic Shock (12), Septic (28), and Other (23). At least 1 abnormal value was found in 18/28 (64%) samples from the Septic Shock group, 66/85 (78%) from the Septic group, and 30/59 (51%) from the Other group (P= .01). Coagulopathy (3 or more abnormal values) was present in 7/28 (25%) samples in the Septic Shock group, 14/85 (16%) samples in the Septic group, and 3/59 (5%) samples in the Other group (P= .0028). Clinically detectable bleeding occurred in 8/12 (67%) Septic Shock cases, 11/28 (39%) Septic cases, and 3/23 (13%) Other cases (P= .009). Foals in Septic Shock were 12.7 times more likely to have clinical evidence of bleeding than those in the Other group (95% CI 2.3-70, P= .004). Treatment with fluids or plasma did not have a detectable effect on coagulation values.

CONCLUSIONS AND CLINICAL IMPORTANCE

Coagulopathy commonly occurs in critically ill neonatal foals, especially those with sepsis and septic shock.

The impact of surfactant protein-A on ozone-induced changes in the mouse bronchoalveolar lavage proteome

Background

Ozone is a major component of air pollution. Exposure to this powerful oxidizing agent can cause or exacerbate many lung conditions, especially those involving innate immunity. Surfactant protein-A (SP-A) plays many roles in innate immunity by participating directly in host defense as it exerts opsonin function, or indirectly via its ability to regulate alveolar macrophages and other innate immune cells. The mechanism(s) responsible for ozone-induced pathophysiology, while likely related to oxidative stress, are not well understood.

Methods

We employed 2-dimensional difference gel electrophoresis (2D-DIGE), a discovery proteomics approach, coupled with MALDI-ToF/ToF to compare the bronchoalveolar lavage (BAL) proteomes in wild type (WT) and SP-A knockout (KO) mice and to assess the impact of ozone or filtered air on the expression of BAL proteins. Using the PANTHER database and the published literature most identified proteins were placed into three functional groups.

Results

We identified 66 proteins and focused our analysis on these proteins. Many of them fell into three categories: defense and immunity; redox regulation; and protein metabolism, modification and chaperones. In response to the oxidative stress of acute ozone exposure (2 ppm; 3 hours) there were many significant changes in levels of expression of proteins in these groups. Most of the proteins in the redox group were decreased, the proteins involved in protein metabolism increased, and roughly equal numbers of increases and decreases were seen in the defense and immunity group. Responses between WT and KO mice were similar in many respects. However, the percent change was consistently greater in the KO mice and there were more changes that achieved statistical significance in the KO mice, with levels of expression in filtered air-exposed KO mice being closer to ozone-exposed WT mice than to filtered air-exposed WT mice.

Conclusion

We postulate that SP-A plays a role in reactive oxidant scavenging in WT mice and that its absence in the KO mice in the presence or absence of ozone exposure results in more pronounced, and presumably chronic, oxidative stress.

Molecular biology of inflammation and sepsis: a primer

BACKGROUND

Remarkable progress has been made during the last decade in defining the molecular mechanisms that underlie septic shock. This rapidly expanding field is leading to new therapeutic opportunities in the management of severe sepsis.

AIM

To provide the clinician with a timely summary of the molecular biology of sepsis and to better understand recent advances in sepsis research.

DATA SELECTION

Medline search of relevant publications in basic mechanisms of sepsis/severe sepsis/septic shock, and selected literature review of other manuscripts about the signalosome, inflammasome, apoptosis, or mechanisms of shock. DATA SYNTHESIS AND FINDINGS: The identification of the toll-like receptors and the associated concept of innate immunity based upon pathogen- or damage-associated molecular pattern molecules allowed significant advances in our understanding of the pathophysiology of sepsis. The essential elements of the inflammasome and signal transduction networks responsible for activation of the host response have now been characterized. Apoptosis, mitochondrial dysfunction, sepsis-related immunosuppression, late mediators of systemic inflammation, control mechanisms for coagulation, and reprogramming of immune response genes all have critical roles in the development of sepsis.

CONCLUSIONS

Many of these basic discoveries have direct implications for the clinical management of sepsis. The translation of these "bench-to-bedside" findings into new therapeutic strategies is already underway. This brief review provides the clinician with a primer into the basic mechanisms responsible for the molecular biology of sepsis, severe sepsis, and septic shock.

Protein kinase C-delta and phosphatidylinositol 3-kinase/Akt activate mammalian target of rapamycin to modulate NF-kappaB activation and intercellular adhesion molecule-1 (ICAM-1) expression in endothelial cells

We have shown that the mammalian target of rapamycin (mTOR) down-regulates thrombin-induced ICAM-1 expression in endothelial cells by suppressing the activation of NF-kappaB. However, the mechanisms by which mTOR is activated to modulate these responses remain to be addressed. Here, we show that thrombin engages protein kinase C (PKC)-delta and phosphattidylinositol 3-kinase (PI3K)/Akt pathways to activate mTOR and thereby dampens NF-kappaB activation and intercellular adhesion molecule 1 (ICAM-1) expression. Stimulation of human vascular endothelial cells with thrombin induced the phosphorylation of mTOR and its downstream target p70 S6 kinase in a PKC-delta- and PI3K/Akt-dependent manner. Consistent with this, thrombin-induced phosphorylation of p70 S6 kinase was defective in embryonic fibroblasts from mice with targeted disruption of PKC-delta (Pkc-delta(-)(/)(-)), p85alpha and p85beta subunits of the PI3K (p85alpha(-)(/)(-)beta(-)(/)(-)), or Akt1 and Akt2 (Akt1(-)(/)(-)2(-)(/)(-)). Furthermore, we observed that expression of the constitutively active form of PKC-delta or Akt was sufficient to induce NF-kappaB activation and ICAM-1 expression, and that co-expression of mTOR suppressed these responses. In reciprocal experiments, inhibition/depletion of mTOR augmented NF-kappaB activation and ICAM-1 expression induced by PKC-delta or Akt. In control experiments, increasing or impairing mTOR signaling by the above approaches produced similar effects on NF-kappaB activation and ICAM-1 expression induced by thrombin. Thus, these data reveal an important role of PKC-delta and PI3K/Akt pathways in activating mTOR as an endogenous modulator to ensure a tight regulation of NF-kappaB signaling of ICAM-1 expression in endothelial cells.

Tissue factor as an initiator of coagulation and inflammation in the lung

Patients with severe infections almost invariably exhibit evidence of activation of the coagulation system. The lungs are amongst the most frequently affected organs during severe infection and sepsis. The abundant presence of intravascular and extravascular fibrin appears to be a specific hallmark of acute lung injury after sepsis. Tissue factor (TF) is regarded to be the primary initiator of coagulation in severe infection. Effective blockade of the TF pathway, either by recombinant TF pathway inhibitor or by anti-TF antibodies in experimental sepsis, attenuates lung injury and partially prevents pulmonary dysfunction. In addition, inhibition of the activity of TF prevents local activation of coagulation in models of pneumonia. The TF pathway can influence inflammatory signaling by activation of protease activated receptor-1 and -2. This review presents the most recent data on the crosstalk between TF-mediated coagulation and inflammation, with a specific emphasis on these processes in the lung.

The increase of endothelial progenitor cells in the peripheral blood: a new parameter for detecting onset and severity of sepsis

Sepsis is a clinical syndrome characterized by non-specific inflammatory response with evidence of profound changes in the function and structure of endothelium. Recent evidence suggests that vascular maintenance, repair and angiogenesis are in part mediated by recruitment from bone marrow (BM) of endothelial progenitor cells (EPCs). In this study we were interested in whether EPCs are increasingly mobilized during sepsis and if this mobilization is associated with sepsis severity. Our flow cytometry data demonstrate that in the CD34+ cell gate the number of EPCs in the blood of patients with sepsis had a four-fold increase (45 +/- 4.5% p < 0.001) compared to healthy controls (12 +/- 3.6%) and that this increase was already evident at 6 hours from diagnosis (40.6 +/- 4.2 percent), reaching its maximum at 72 hours. Also the percentage of cEPCs identified in the patients with sepsis (35 +/- 4.6% of the CD34+ cell) was statistically different (p < 0.001) compared to that found in the blood of patients with severe sepsis (75 +/- 4.9%). In addition, we proved that at six hours after sepsis diagnosis, VEGF, CXCL8 and CXCL12 serum levels were significantly higher in septic patients compared to healthy volunteers 559 +/- 82.14 pg/ml vs 2.9 +/- 0.6 (p < 0.0001), 189.8 +/- 67.3 pg/ml 15 vs 11.9 +/- 1.6 (p = 0.014) and 780.5 +/- 106.5 pg/ml; vs 190.2 +/- 71.4 (p < 0.001). Our data suggest that the cEPC evaluation in peripheral blood, even at early times of diagnosis, in patients with sepsis can be envisaged as a valuable parameter to confirm diagnosis and suggest further prognosis.

High versus standard-volume haemofiltration in hyperdynamic porcine peritonitis: effects beyond haemodynamics?

OBJECTIVE

The role of haemofiltration as an adjunctive treatment of sepsis remains a contentious issue. To address the role of dose and to explore the biological effects of haemofiltration we compared the effects of standard and high-volume haemofiltration (HVHF) in a peritonitis-induced model of porcine septic shock.

DESIGN AND SETTING

Randomized, controlled experimental study.

SUBJECTS

Twenty-one anesthetized and mechanically ventilated pigs.

INTERVENTIONS

After 12 h of hyperdynamic peritonitis, animals were randomized to receive either supportive treatment (Control, n = 7) or standard haemofiltration (HF 35 ml/kg per h, n = 7) or HVHF (100 ml/kg per hour, n = 7).

MEASUREMENTS AND RESULTS

Systemic and hepatosplanchnic haemodynamics, oxygen exchange, energy metabolism (lactate/pyruvate, ketone body ratios), ileal and renal cortex microcirculation and systemic inflammation (TNF-alpha, IL-6), nitrosative/oxidative stress (TBARS, nitrates, GSH/GSSG) and endothelial/coagulation dysfunction (von Willebrand factor, asymmetric dimethylarginine, platelet count) were assessed before, 12, 18, and 22 h of peritonitis. Although fewer haemofiltration-treated animals required noradrenaline support (86, 43 and 29% animals in the control, HF and HVHF groups, respectively), neither of haemofiltration doses reversed hyperdynamic circulation, lung dysfunction and ameliorated alterations in gut and kidney microvascular perfusion. Both HF and HVHF failed to attenuate sepsis-induced alterations in surrogate markers of cellular energetics, nitrosative/oxidative stress, endothelial injury or systemic inflammation.

CONCLUSIONS

In this porcine model of septic shock early HVHF proved superior in preventing the development of septic hypotension. However, neither of haemofiltration doses was capable of reversing the progressive disturbances in microvascular, metabolic, endothelial and lung function, at least within the timeframe of the study and severity of the model.

The adenosine deaminase inhibitor erythro-9-[2-hydroxyl-3-nonyl]-adenine decreases intestinal permeability and protects against experimental sepsis: a prospective, randomised laboratory investigation

INTRODUCTION

The treatment of septic conditions in critically ill patients is still one of medicine's major challenges. Cyclic nucleotides, adenosine and its receptors play a pivotal role in the regulation of inflammatory responses and in limiting inflammatory tissue destruction. The aim of this study was to verify the hypothesis that adenosine deaminase-1 and cyclic guanosine monophosphate-stimulated phosphodiesterase inhibition by erythro-9-[2-hydroxyl-3-nonyl]-adenine could be beneficial in experimental endotoxicosis/sepsis.

METHOD

We used two established animal models for endotoxicosis and sepsis. Twenty-four male Wistar rats that had been given intravenous endotoxin (Escherichia coli lipopolysaccharide) were treated with either erythro-9-[2-hydroxyl-3-nonyl]-adenine infusion or 0.9% saline during a study length of 120 minutes. Sepsis in 84 female C57BL/6 mice was induced by caecal ligation and puncture. Animals were treated with repeated erythro-9-[2-hydroxyl-3-nonyl]-adenine injections after 0, 12 and 24 hours or 4, 12 and 24 hours for delayed treatment.

RESULTS

In endotoxaemic rats, intestinal production of hypoxanthine increased from 9.8 +/- 90.2 micromol/l at baseline to 411.4 +/- 124.6 micromol/l and uric acid formation increased from 1.5 +/- 2.3 mmol/l to 13.1 +/- 2.7 mmol/l after 120 minutes. In endotoxaemic animals treated with erythro-9-[2-hydroxyl-3-nonyl]-adenine, we found no elevation of adenosine metabolites. The lactulose/L-rhamnose ratio (14.3 versus 4.2 in control animals; p = 2.5 x 10(-7)) reflects a highly permeable small intestine and through the application of erythro-9-[2-hydroxyl-3-nonyl]-adenine, intestinal permeability could be re-established. The lipopolysaccharide animals had decreased L-rhamnose/3-O-methyl-D-glucose urine excretion ratios. Erythro-9-[2-hydroxyl-3-nonyl]-adenine reduced this effect. The mucosa damage score of the septic animals was higher compared with control and therapy animals (p < 0.05). Septic shock induction by caecal ligation and puncture resulted in a 160-hour survival rate of about 25%. In contrast, direct adenosine deaminase-1 inhibition resulted in a survival rate of about 75% (p = 0.0018). A protective effect was still present when erythro-9-[2-hydroxyl-3-nonyl]-adenine treatment was delayed for four hours (55%, p = 0.029).

CONCLUSIONS

We present further evidence of the beneficial effects achieved by administering erythro-9-[2-hydroxyl-3-nonyl]-adenine, an adenosine deaminase-1 and cyclic guanosine monophosphate-stimulated phosphodiesterase inhibitor, in an endotoxicosis and sepsis animal model. This suggests a potential therapeutic option in the treatment of septic conditions.

Formation of composite endothelial cell-mesenchymal stem cell islets: a novel approach to promote islet revascularization

OBJECTIVE

Mesenchymal stem cells (MSCs) contribute to endothelial cell (EC) migration by producing proteases, thereby paving the way into the tissues for ECs. MSCs were added to our previously described composite EC islets as a potential means to improve their capacity for islet angiogenesis.

RESEARCH DESIGN AND METHODS

Human islets were coated with primary human bone marrow-derived MSCs and dermal microvascular ECs. The capacity of ECs, with or without MSCs, to adhere to and grow into human islets was analyzed. The survival and functionality of these composite islets were evaluated in a dynamic perifusion assay, and their capacity for angiogenesis in vitro was assessed in a three-dimensional fibrin gel assay.

RESULTS

ECs proliferated after culture in MSC-conditioned medium, and MSCs improved the EC coverage threefold compared with EC islets alone. Islet survival in vitro and the functionality of the composite islets after culture were equal to those of control islets. The EC-MSC islets showed a twofold increase in total sprout formation compared with EC islets, and vascular sprouts emanating from the EC-MSC-islet surface showed migration of ECs into the islets and also into the surrounding matrix, either alone or in concert with MSCs.

CONCLUSIONS

EC proliferation, sprout formation, and ingrowth of ECs into the islets were enhanced by MSCs. The use of composite EC-MSC islets may have beneficial effects on revascularization and immune regulation. The technique presented allows for pretreatment of donor islets with recipient-derived ECs and MSCs as a means of improving islet engraftment.

Leukocyte activation: the link between inflammation and coagulation during heatstroke. A study of patients during the 2003 heat wave in Paris

OBJECTIVE

The mechanisms linking severe inflammation and coagulation during heatstroke are poorly understood. Here, we examined the roles of the tissue factor pathway, leukocyte activation, and mediators of innate immunity in patients admitted to an intensive care unit for heatstroke during an intense heat wave in Paris.

DESIGN

Retrospective observational study.

SETTING

Intensive care unit of a university medical center.

PATIENTS

Eighteen critically ill severe patients with heatstroke were enrolled in the study and 14 age-matched patients with severe sepsis as controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

High circulating levels of some inflammation and stress mediators (interleukin-6, -8, C5a, interleukin-1 receptor antagonist, heat shock protein 60 and 70) were observed. Blood leukocyte activation was shown by beta2 integrin up-regulation, L-selectin down-regulation, and strong production of reactive oxygen species and interleukin-8 ex vivo. High levels of circulating promatrix metalloproteinase-9 were detected in all the patients studied, and its active form was present in two patients. Overt disseminated intravascular coagulation according to the International Society of Thrombosis and Hemostasis score was present in five patients. Whole-blood tissue factor was present in all the patients and part of this activity was associated with microparticles in five patients. The degrees of inflammation and disseminated intravascular coagulation are correlated with clinical severity.

CONCLUSIONS

These results suggest that neutrophil activation plays a key role in the acute activation of coagulation observed during severe heatstroke, despite a rapid and sustained antiinflammatory response. The comparison with a group of patients with severe sepsis suggests some common mechanisms, but more intense responses during heatstroke.

Induction of TLR2 expression by inflammatory stimuli is required for endothelial cell responses to lipopeptides

Human endothelial cells (EC) express Toll-like receptor 4 (TLR4), a receptor for lipopolysaccharides (LPS), but little or no TLR2, a lipopeptide receptor. The aim of this study was to investigate to what extent inflammatory stimuli modify the expression by EC of TLR4 and TLR2, of the TLR2 co-receptors TLR1 and TLR6 and of the TLR2-accessory proteins CD14 and CD36. Stimulation of umbilical vein derived EC with TNF-alpha, LPS or IL-1beta for 24h induced a strong increase in TLR2 mRNA but not in TLR1, TLR4 and TLR6 mRNA. Inflammatory activation had little effect on CD14 mRNA, but decreased the expression of CD36 mRNA. TLR2 antigen was readily detected by flow cytometry on activated EC, but not on resting EC. A significant proportion of TLR2 was found to be located intracellularly. By using specific signalling pathway inhibitors we established that the induction of TLR2 by inflammatory stimuli was dependent on NF-kappaB, p38-MAP kinase and c-Jun kinase. IRAK-1 phosphorylation after treatment with 10mug/ml of lipoteichoic acid (LTA), a TLR2 agonist, was only observed in TNF-alpha-stimulated EC and not in resting EC. Furthermore, LTA potentiated the increase of the inflammatory markers E-Selectin or IL-8 in EC pre-treated with TNF-alpha, LPS or IL-1beta, but not in resting EC. These results imply that the up-regulated TLR2 is functionally active. Interestingly, LTA had no effect on TLR2 expression, nor maintained TLR2 expression, in activated EC. This suggests that lipopeptide responses of EC are dependent on the continued presence of inflammatory cytokines, provided by other cell types, or LPS. In conclusion, inflammatory stimuli induce a high TLR2 expression in EC, which in turn enables the cells to strongly respond to lipopeptides. The up-regulation of TLR2 may be of relevance for the vascular effects of Gram-positive bacteria.

[An endogenous dithiol with antioxidant properties: alpha-lipoic acid, potential uses in cardiovascular diseases]

Alpha-Lipoic acid (ALA) is a natural compound, chemically named 1,2-dithiolane-3-pentanoic acid, also referred to as thioctic acid. In humans, ALA is synthetized by the liver and other tissues with high metabolic activity: heart, kidney. ALA is both water and fat soluble and therefore, is widely distributed in both cellular membranes and cytosol. Recently, a greater deal of attention has been given to antioxidant function for ALA and its reduced formed: dihydrolipoic acid (DHLA). ALA scavenges hydroxyl radicals, hypochlorous acid and singlet oxygen. It may also exert antioxidant effects in biological systems through transitional metal chelation. Dihydrolipoic acid has been shown to have antioxidant but also pro-oxidant properties in systems in which hydroxyl radical was generated. ALA/DHLA ratio has the capacity to recycle endogenous antioxidants such as vitamin E. A number of experimental as well as clinical studies point to the usefulness of ALA as a therapeutic agent for such diverse conditions as diabetes, atherosclerosis, insulin resistance, neuropathy, neurodegenerative diseases and ischemia-reperfusion injury. ALA represents a potential agent on the vascular endothelium, recording to ALA/DHLA redox couple is one of the most powerful biological antioxidant systems.

The pathology of scleroderma vascular disease

Systemic sclerosis is characterized by three distinct pathologic processes: fibrosis, cellular/humoral autoimmunity, and specific vascular changes. Although a mild vasculitis may sometimes be present, the vascular pathology of scleroderma is not necessarily inflammatory and is best characterized as a vasculopathy. In this article, the authors propose that SSc vasculopathy is the result of an early event involving vascular injury that eventuates in a vicious cycle mediated in part by the immune process. The subsequent vascular malformation and rarefaction may be a function of systemic angiogenic dysregulation, with over expression of vascular endothelial growth factor but a lack of proper interactions with smooth muscle cells needed to stabilize and organize blood vessels.