Inflammation, endothelium, and coagulation in sepsis

Recombinant human thrombomodulin inhibits neutrophil extracellular trap formation in vitro

The aim of this study was to investigate the effects of recombinant human-soluble thrombomodulin (rTM) on lipopolysaccharide (LPS)-induced, platelet-dependent neutrophil extracellular trap (NET) formation (NETosis). Human peripheral blood neutrophils and platelets were co-incubated with or without LPS (0.2 μg/ml) in the presence and absence of rTM (2 μg/ml). NETosis was confirmed by immunostaining and confocal microscopy. In the absence of platelets, LPS did not induce NETosis in the neutrophils. NETosis, however, was induced by LPS when neutrophils were co-cultured with platelets (64 % of neutrophils). Notably, rTM was able to fully inhibit NETosis in neutrophils cultured with platelets and in the presence of LPS. rTM did not induce NETosis in this co-culture system (p < 0.01 versus LPS in the absence of rTM). These results show that rTM can suppress LPS-induced platelet-dependent NETosis in vitro.

AMA0428, A Potent Rock Inhibitor, Attenuates Early and Late Experimental Diabetic Retinopathy

PURPOSE

Diabetic retinopathy (DR) is characterized by an early stage of inflammation and vessel leakage, and an advanced vasoproliferative stage. Also, neurodegeneration might play an important role in disease pathogenesis. The aim of this study was to investigate the effect of the Rho kinase (ROCK) inhibitor, AMA0428, on these processes.

METHODS

The response to ROCK inhibition by AMA0428 (1 µg) was studied in vivo using the murine model for streptozotocin (STZ)-induced diabetes, focusing on early non-proliferative DR features and the oxygen-induced retinopathy (OIR) model to investigate proliferative DR. Intravitreal (IVT) administration of AMA0428 was compared with murine anti-VEGF-R2 antibody (DC101, 6.2 µg) and placebo (H₂O/PEG; 1C8). Outcome was assessed by analyzing leukostasis using fluorescein isothiocyanate coupled concanavalin A (FITC-ConA) and vessel leakage (bovine serum albumin conjugated with fluorescein isothiocyanate; FITC-BSA)/neovascularization and neurodegeneration by immunohistological approaches (hematoxylin and eosin (H&E), terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL), Brn3a). ELISA and Western blotting were employed to unravel the consequences of ROCK inhibition (1 µM AMA0428) on myosin phosphatase target protein (MYPT)-1 phosphorylation, endothelial nitric oxide synthase (eNOS) phosphorylation, and vascular endothelial growth factor (VEGF) levels in retinas of diabetic mice, on NF-κβ activity and ICAM-1 expression in endothelial cells (ECs).

RESULTS

In vivo, AMA0428 significantly reduced vessel leakage and neovascularization, respectively, in the STZ and OIR model, comparable to DC101 therapy. Additionally, the ROCK inhibitor decreased neurodegeneration in both models and inhibited leukostasis by 30% (p < 0.05) in the STZ model (p < 0.05), while DC101 had no positive effect on the outcome of these latter processes. ROCK activity was upregulated in the diabetic retina and AMA0428 administration resulted in decreased phospho-MYPT-1, enhanced phospho-eNOS, and reduced VEGF levels. In vitro, AMA0428 interfered with NF-κβ activity, thereby inhibiting ICAM-1 expression in ECs.

CONCLUSIONS

Targeting ROCK with AMA0428 effectively attenuated outcome in an early DR model (STZ) and a late vasoproliferative retinopathy model (OIR). These findings make AMA0428 a promising candidate with an additional anti-inflammatory and neuroprotective benefit for DR patients, as compared with anti-VEGF treatment.

Endothelium-Derived 5-Methoxytryptophan Is a Circulating Anti-Inflammatory Molecule That Blocks Systemic Inflammation

Rationale:

Systemic inflammation has emerged as a key pathophysiological process that induces multiorgan injury and causes serious human diseases. Endothelium is critical in maintaining cellular and inflammatory homeostasis, controlling systemic inflammation, and progression of inflammatory diseases. We postulated that endothelium produces and releases endogenous soluble factors to modulate inflammatory responses and protect against systemic inflammation.

Objective:

To identify endothelial cell–released soluble factors that protect against endothelial barrier dysfunction and systemic inflammation.

Methods and Results:

We found that conditioned medium of endothelial cells inhibited cyclooxgenase-2 and interleukin-6 expression in macrophages stimulated with lipopolysaccharide. Analysis of conditioned medium extracts by liquid chromatography–mass spectrometry showed the presence of 5-methoxytryptophan (5-MTP), but not other related tryptophan metabolites. Furthermore, endothelial cell–derived 5-MTP suppressed lipopolysaccharide-induced inflammatory responses and signaling in macrophages and endotoxemic lung tissues. Lipopolysaccharide suppressed 5-MTP level in endothelial cell-conditioned medium and reduced serum 5-MTP level in the murine sepsis model. Intraperitoneal injection of 5-MTP restored serum 5-MTP accompanied by the inhibition of lipopolysaccharide-induced endothelial leakage and suppression of lipopolysaccharide- or cecal ligation and puncture–mediated proinflammatory mediators overexpression. 5-MTP administration rescued lungs from lipopolysaccharide-induced damages and prevented sepsis-related mortality. Importantly, compared with healthy subjects, serum 5-MTP level in septic patients was decreased by 65%, indicating an important clinical relevance.

Conclusions:

We conclude that 5-MTP belongs to a novel class of endothelium-derived protective molecules that defend against endothelial barrier dysfunction and excessive systemic inflammatory responses.

Role in proinflammatory response of YghJ, a secreted metalloprotease from neonatal septicemic Escherichia coli

Neonatal sepsis is the invasion of microbial pathogens into blood stream and is associated with a systemic inflammatory response with production and release of a wide range of inflammatory mediators. The increased serum levels of cytokines were found to correlate with the severity and mortality in course of sepsis. There have been no reports on the role of microbial proteases in stimulation of proinflammatory response in neonatal sepsis. We have identified YghJ, a secreted metalloprotease from a neonatal septicemic Escherichia coli (NSEC) isolate. The protease was partially purified from culture supernatant by successive anion and gel filtration chromatography. MS/MS peptide sequencing of the protease showed homology with YghJ. YghJ was cloned, expressed and purified in pBAD TOPO expression vector. YghJ was found to be proteolytically active against Methoxysuccinyl Ala-Ala-Pro-Met-p-nitroanilide oligopeptide substrate, but not against casein and gelatin. YghJ showed optimal activity at pH 7-8 and at temperatures 37-40°C. YghJ showed clear changes in cellular morphologies of Int407, HT-29 and HEK293 cells. YghJ stimulated the secretion of cytokines IL-1α, IL-1β and TNF-α in murine macrophages (RAW 264.7) and IL-8 from human intestinal epithelial cells (HT-29). YghJ also down-regulated the production of anti-inflammatory cytokines such as IL-10. YghJ is present in both septicemic (78%) and fecal E. coli isolates (54%). However, expression and secretion of YghJ is significantly higher among the septicemic (89%) than the fecal isolates (33%). This is the first study to show the role of a microbial protease, YghJ in triggering proinflammatory response in NSEC.

Acid Sphingomyelinase Promotes Endothelial Stress Response in Systemic Inflammation and Sepsis

The pathophysiology of sepsis involves activation of acid sphingomyelinase (SMPD1) with subsequent generation of the bioactive mediator ceramide. We herein evaluated the hypothesis that the enzyme exerts biological effects in endothelial stress response. Plasma-secreted sphingomyelinase activity, ceramide generation and lipid raft formation were measured in human microcirculatory endothelial cells (HMEC-1) stimulated with serum obtained from sepsis patients. Clustering of receptors relevant for signal transduction was studied by immuno staining. The role of SMPD1 for macrodomain formation was tested by pharmacological inhibition. To confirm the involvement of the stress enzyme, direct inhibitors (amino bisphosphonates) and specific downregulation of the gene was tested with respect to ADAMTS13 expression and cytotoxicity. Plasma activity and amount of SMPD1 were increased in septic patients dependent on clinical severity. Increased breakdown of sphingomyelin to ceramide in HMECs was observed following stimulation with serum from sepsis patients in vitro. Hydrolysis of sphingomyelin, clustering of receptor complexes, such as the CD95L/Fas-receptor, as well as formation of ceramide enriched macrodomains was abrogated using functional inhibitors (desipramine and NB6). Strikingly, the stimulation of HMECs with serum obtained from sepsis patients or mixture of proinflammatory cytokines resulted in cytotoxicity and ADAMTS13 downregulation which was abrogated using desipramine, amino bisphosphonates and genetic inhibitors. SMPD1 is involved in the dysregulation of ceramide metabolism in endothelial cells leading to macrodomain formation, cytotoxicity and downregulation of ADAMTS13 expression. Functional inhibitors, such as desipramine, are capable to improve endothelial stress response during sepsis and might be considered as a pharmacological treatment strategy to favor the outcome.

Cold-inducible RNA-binding protein causes endothelial dysfunction via activation of Nlrp3 inflammasome

Cold-inducible RNA-binding protein (CIRP) is a damage-associated molecular pattern (DAMP) molecule which stimulates proinflammatory cytokine release in hemorrhage and sepsis. Under these medical conditions, disruption of endothelial homeostasis and barrier integrity, typically induced by proinflammatory cytokines, is an important factor contributing to morbidity and mortality. However, the role of CIRP in causing endothelial dysfunction has not been investigated. In this study, we show that intravenous injection of recombinant murine CIRP (rmCIRP) in C57BL/6 mice causes lung injury, evidenced by vascular leakage, edema, increased leukocyte infiltration and cytokine production in the lung tissue. The CIRP-induced lung damage is accompanied with endothelial cell (EC) activation marked by upregulation of cell-surface adhesion molecules E-selectin and ICAM-1. Using in vitro primary mouse lung vascular ECs (MLVECs), we demonstrate that rmCIRP treatment directly increases the ICAM-1 protein expression and activates NAD(P)H oxidase in MLVECs. Importantly, CIRP stimulates the assembly and activation of Nlrp3 inflammasome in MLVECs accompanied with caspase-1 activation, IL-1β release and induction of proinflammatory cell death pyroptosis. Finally, our study demonstrates CIRP-induced EC pyroptosis in the lungs of C57BL/6 mice for the first time. Taken together, the released CIRP in shock can directly activate ECs and induce EC pyroptosis to cause lung injury.

Proteome analysis of mast cell releasates reveals a role for chymase in the regulation of coagulation factor XIIIA levels via proteolytic degradation

BACKGROUND

Mast cells are significantly involved in IgE-mediated allergic reactions; however, their roles in health and disease are incompletely understood.

OBJECTIVE

We aimed to define the proteome contained in mast cell releasates on activation to better understand the factors secreted by mast cells that are relevant to the contribution of mast cells in diseases.

METHODS

Bone marrow-derived cultured mast cells (BMCMCs) and peritoneal cell-derived mast cells were used as "surrogates" for mucosal and connective tissue mast cells, respectively, and their releasate proteomes were analyzed by mass spectrometry.

RESULTS

Our studies showed that BMCMCs and peritoneal cell-derived mast cells produced substantially different releasates following IgE-mediated activation. Moreover, we observed that the transglutaminase coagulation factor XIIIA (FXIIIA) was one of the most abundant proteins contained in the BMCMC releasates. Mast cell-deficient mice exhibited increased FXIIIA plasma and activity levels as well as reduced bleeding times, indicating that mast cells are more efficient in their ability to downregulate FXIIIA than in contributing to its amounts and functions in homeostatic conditions. We found that human chymase and mouse mast cell protease-4 (the mouse homologue of human chymase) had the ability to reduce FXIIIA levels and function via proteolytic degradation. Moreover, we found that chymase deficiency led to increased FXIIIA amounts and activity, as well as reduced bleeding times in homeostatic conditions and during sepsis.

CONCLUSIONS

Our study indicates that the mast cell protease content can shape its releasate proteome. Moreover, we found that chymase plays an important role in the regulation of FXIIIA via proteolytic degradation.

The anti-aging effects of LW-AFC via correcting immune dysfunctions in senescence accelerated mouse resistant 1 (SAMR1) strain

Although there were considerable advances in the anti-aging medical field, it is short of therapeutic drug for anti-aging. Mounting evidence indicates that the immunosenescence is the key physiopathological mechanism of aging. This study showed the treatment of LW-AFC, an herbal medicine, decreased the grading score of senescence, increased weight, prolonged average life span and ameliorated spatial memory impairment in 12- and 24-month-old senescence accelerated mouse resistant 1 (SAMR1) strain. And these anti-aging effects of LW-AFC were more excellent than melatonin. The administration of LW-AFC enhanced ConA- and LPS-induced splenocyte proliferation in aged SAMR1 mice. The treatment of LW-AFC not only reversed the decreased the proportions of helper T cells, suppressor T cells and B cells, the increased regulatory T cells in the peripheral blood of old SAMR1 mice, but also could modulate the abnormal secretion of IL-1β, IL-2, IL-6, IL-17, IL-23, GM-CSF, IFN-γ, TNF-α, TNF-β, RANTES, eotaxin, MCP-1, IL-4, IL-5, IL-10 and G-CSF. These data indicated that LW-AFC reversed the immunosenescence status by restoring immunodeficiency and decreasing chronic inflammation and suggested LW-AFC may be an effective anti-aging agent.

Coagulopathy and its management in patients with severe burns

Severe burn injury is associated with systemic coagulopathy. The changes in coagulation described in patients with severe burns resemble those found patients with sepsis or major trauma. Coagulopathy in patients with severe burns is characterized by procoagulant changes, and impaired fibrinolytic and natural anticoagulation systems. Both the timing of onset and the severity of hemostatic derangements are related to the severity of the burn. The exact pathophysiology and time course of coagulopathy are uncertain, but, at least in part, result from hemodilution and hypothermia. As the occurrence of coagulopathy in patients with severe burns is associated with increased comorbidity and mortality, coagulopathy could be seen as a potential therapeutic target. Clear guidelines for the treatment of coagulopathy in patients with severe burns are lacking, but supportive measures and targeted treatments have been proposed. Supportive measures are aimed at avoiding preventable triggers such as tissue hypoperfusion caused by shock, or hemodilution and hypothermia following the usually aggressive fluid resuscitation in these patients. Suggested targeted treatments that could benefit patients with severe burns include systemic treatment with anticoagulants, but sufficient randomized controlled trial evidence is lacking.

Antithrombotic and antiplatelet activities of vicenin-2

Cyclopia subternata is a medicinal plant commonly used in traditional medicine to relieve pain in physiological processes. However, there are limited modern data on its pharmacological effects and active components relating to its traditional use. Here, the anticoagulant and antiplatelet activities of vicenin-2 (VCN), an active compound in C. subternata, were determined. The anticoagulant activities were investigated by monitoring activated partial thromboplastin time (aPTT), prothrombin time (PT), and the activities of thrombin and activated factor X (FXa). The effects of VCN on the expression of plasminogen activator inhibitor type 1 (PAI-1) and tissue-type plasminogen activator (t-PA) were evaluated in tumor necrosis factor (TNF)-α-activated human umbilical vein endothelial cells (HUVECs). Treatment with VCN resulted in prolonged aPTT and PT and inhibition of the activities of thrombin and FXa, as well as inhibited production of thrombin and FXa in HUVECs. In addition, VCN inhibited thrombin-catalyzed fibrin polymerization and platelet aggregation. VCN also elicited anticoagulant effects in mice. In addition, treatment with VCN resulted in significant reduction of the PAI-1 to t-PA ratio. Collectively, VCN possesses antithrombotic activities and offers a basis for development of a novel anticoagulant.

Does Citrulline Have Protective Effects on Liver Injury in Septic Rats?

Citrulline (Cit) supplementation was proposed to serve as a therapeutic intervention to restore arginine (Arg) concentrations and improve related functions in sepsis. This study explored whether citrulline had positive effects on liver injury and cytokine release in the early stages of sepsis. The cecal ligation and puncture (CLP) model was utilized in our study. Rats were divided into four groups: normal, Cit, CLP, and CLP+Cit. The CLP group and CLP+Cit group were separated into 6-, 12-, and 24-hour groups, according to the time points of sacrifice after surgery. Intragastric administration of L-citrulline was applied to rats in Cit and CLP+Cit groups before surgery. Serum AST and ALT levels and levels of MDA, SOD, NO, and iNOS in the liver tissues were evaluated. Plasma concentrations of Cit and Arg were assessed using HPLC-MS/MS. Serum concentrations of cytokines and chemokines were calculated by Luminex. Results showed SOD activities of CLP+Cit groups were significantly higher than that of CLP groups, contrasting with the MDA and NO levels which were significantly lower in CLP+Cit groups than in CLP groups. In addition, plasma concentrations of TNF-α, IL-6, and IL-1β were significantly lower in the CLP+Cit 6-hour group than in the CLP 6-hour group.

Therapeutic treatment with ascorbate rescues mice from heat stroke-induced death by attenuating systemic inflammatory response and hypothalamic neuronal damage

The impact of ascorbate on oxidative stress-related diseases is moderate because of its limited oral bioavailability and rapid clearance. However, recent evidence of the clinical benefit of parenteral vitamin C administration has emerged, especially in critical care. Heatstroke is defined as a form of excessive hyperthermia associated with a systemic inflammatory response that results in multiple organ dysfunctions in which central nervous system disorders such as delirium, convulsions, and coma are predominant. The thermoregulatory, immune, coagulation and tissue injury responses of heatstroke closely resemble those observed during sepsis and are likely mediated by similar cellular mechanisms. This study was performed by using the characteristic high lethality rate and sepsis-mimic systemic inflammatory response of a murine model of heat stroke to test our hypothesis that supra-physiological doses of ascorbate may have therapeutic use in critical care. We demonstrated that parenteral administration of ascorbate abrogated the lethality and thermoregulatory dysfunction in murine model of heat stroke by attenuating heat stroke-induced accelerated systemic inflammatory, coagulation responses and the resultant multiple organ injury, especially in hypothalamus. Overall, our findings support the hypothesis and notion that supra-physiological doses of ascorbate may have therapeutic use in critical care.

Sepsis-induced elevation in plasma serotonin facilitates endothelial hyperpermeability

Hyperpermeability of the endothelial barrier and resulting microvascular leakage are a hallmark of sepsis. Our studies describe the mechanism by which serotonin (5-HT) regulates the microvascular permeability during sepsis. The plasma 5-HT levels are significantly elevated in mice made septic by cecal ligation and puncture (CLP). 5-HT-induced permeability of endothelial cells was associated with the phosphorylation of p21 activating kinase (PAK1), PAK1-dependent phosphorylation of vimentin (P-vimentin) filaments, and a strong association between P-vimentin and ve-cadherin. These findings were in good agreement with the findings with the endothelial cells incubated in serum from CLP mice. In vivo, reducing the 5-HT uptake rates with the 5-HT transporter (SERT) inhibitor, paroxetine blocked renal microvascular leakage and the decline in microvascular perfusion. Importantly, mice that lack SERT showed significantly less microvascular dysfunction after CLP. Based on these data, we propose that the increased endothelial 5-HT uptake together with 5-HT signaling disrupts the endothelial barrier function in sepsis. Therefore, regulating intracellular 5-HT levels in endothelial cells represents a novel approach in improving sepsis-associated microvascular dysfunction and leakage. These new findings advance our understanding of the mechanisms underlying cellular responses to intracellular/extracellular 5-HT ratio in sepsis and refine current views of these signaling processes during sepsis.

Antithrombotic and antiplatelet activities of small-molecule alkaloids from Scolopendra subspinipes mutilans

The aim of this study was to discover small-molecule anticoagulants from Scolopendra subspinipes mutilans (SSM). A new acylated polyamine (1) and a new sulfated quinoline alkaloid (2) were isolated from SSM. Treatment with the new alkaloids 1, 2, and indole acetic acid 4 prolonged the activated partial thromboplastin time and prothrombin time and inhibited the activity and production of thrombin and activated factor X. Furthermore, compounds 1, 2, and 4 inhibited thrombin-catalyzed fibrin polymerization and platelet aggregation. In accordance with these potential in vitro antiplatelet activities, compounds 1, 2, and 4 showed enhanced antithrombotic effects in an in vivo pulmonary embolism and arterial thrombosis model. Compounds 1, 2, and 4 also elicited anticoagulant effects in mice. Collectively, this study may serve as the groundwork for commercializing SSM or compounds 1, 2, and 4 as functional food components for the prevention and treatment of pathogenic conditions and serve as new scaffolds for the development of anticoagulants.

Broad spectrum immunomodulation using biomimetic blood cell margination for sepsis therapy

Sepsis represents a systemic inflammatory response caused by microbial infection in blood. Herein, we present a novel comprehensive approach to mitigate inflammatory responses through broad spectrum removal of pathogens, leukocytes and cytokines based on biomimetic cell margination. Using a murine model of polymicrobial sepsis induced by cecal ligation and puncture (CLP), we performed extracorporeal blood filtration with the developed microfluidic blood margination (μBM) device. Circulating bacteremia, leukocytes and cytokines in blood decreased post-filtration and significant attenuation of immune cell and cytokine responses were observed 3-5 days after intervention, indicating successful long-term immunomodulation. A dose-dependent effect on long-term immune cell count was also achieved by varying filtration time. As proof of concept for human therapy, the μBM device was scaled up to achieve ∼100-fold higher throughput (∼150 mL h(-1)). With further multiplexing, the μBM technique could be applied in clinical settings as an adjunctive treatment for sepsis and other inflammatory diseases.

Effects of Controlled Cortical Impact on the Mouse Brain Vasculome

Perturbations in blood vessels play a critical role in the pathophysiology of brain injury and neurodegeneration. Here, we use a systematic genome-wide transcriptome screening approach to investigate the vasculome after brain trauma in mice. Mice were subjected to controlled cortical impact and brains were extracted for analysis at 24 h post-injury. The core of the traumatic lesion was removed and then cortical microvesels were isolated from nondirectly damaged ipsilateral cortex. Compared to contralateral cortex and normal cortex from sham-operated mice, we identified a wide spectrum of responses in the vasculome after trauma. Up-regulated pathways included those involved in regulation of inflammation and extracellular matrix processes. Decreased pathways included those involved in regulation of metabolism, mitochondrial function, and transport systems. These findings suggest that microvascular perturbations can be widespread and not necessarily localized to core areas of direct injury per se and may further provide a broader gene network context for existing knowledge regarding inflammation, metabolism, and blood-brain barrier alterations after brain trauma. Further efforts are warranted to map the vasculome with higher spatial and temporal resolution from acute to delayed phase post-trauma. Investigating the widespread network responses in the vasculome may reveal potential mechanisms, therapeutic targets, and biomarkers for traumatic brain injury.

The Outflow Pathway: A Tissue With Morphological and Functional Unity

The trabecular meshwork (TM) plays an important role in high-tension glaucomas. Indeed, the TM is a true organ, through which the aqueous humor flows from the anterior chamber to Schlemm's canal (SC). Until recently, the TM, which is constituted by endothelial-like cells, was described as a kind of passive filter. In reality, it is much more. The cells delineating the structures of the collagen framework of the TM are endowed with a cytoskeleton, and are thus able to change their shape. These cells also have the ability to secrete the extracellular matrix, which expresses proteins and cytokines, and are capable of phagocytosis and autophagy. The cytoskeleton is attached to the nuclear membrane and can, in millionths of a second, send signals to the nucleus in order to alter the expression of genes in an attempt to adapt to biomechanical insult. Oxidative stress, as happens in aging, has a deleterious effect on the TM, leading eventually to cell decay, tissue malfunction, subclinical inflammation, changes in the extracellular matrix and cytoskeleton, altered motility, reduced outflow facility, and (ultimately) increased IOP. TM failure is the most relevant factor in the cascade of events triggering apoptosis in the inner retinal layers, including ganglion cells. J. Cell. Physiol. 231: 1876-1893, 2016. © 2016 Wiley Periodicals, Inc.

Effect of D-glucose feeding on mortality induced by sepsis

Sepsis is the life-threatening response to infection which can lead to tissue damage, organ failure, and death. In the current study, the effect of orally administered D-glucose on the mortality and the blood glucose level induced by D-Galactosamine (GaLN)/lipopolysaccharide (LPS)-induced sepsis was examined in ICR mice. After various amounts of D-glucose (from 1 to 8 g/kg) were orally fed, sepsis was induced by injecting intraperitoneally (i.p.) the mixture of GaLN /LPS. Oral pre-treatment with D-glucose dose-dependently increased the blood glucose level and caused a reduction of sepsis-induced mortality. The oral post-treatment with D-glucose (8 g/kg) up to 3 h caused an elevation of the blood glucose level and protected the mortality observed in sepsis model. However, D-glucose post-treated at 6, 9, or 12 h after sepsis induction did not affect the mortality and the blood glucose level induced by sepsis. Furthermore, the intrathecal (i.t.) pretreatment once with pertussis toxin (PTX; 0.1 µg/5 ml) for 6 days caused a reduction of D-glucose-induced protection of mortality and hyperglycemia. Furthermore, once the hypoglycemic state is continued up to 6 h after sepsis initiated, sepsis-induced mortality could not be reversed by D-glucose fed orally. Based on these findings, it is assumed that the hypoglycemic duration between 3 and 6 h after the sepsis induction may be a critical time of period for the survival. D-glucose-induced protective effect against sepsis-induced mortality appears to be mediated via activating PTX-sensitive G-proteins in the spinal cord. Finally, the production of hyperglycemic state may be critical for the survival against the sepsis-induced mortality.

Chronic antiplatelet therapy is not associated with alterations in the presentation, outcome, or host response biomarkers during sepsis: a propensity-matched analysis

Purpose

Sepsis is a major health burden worldwide. Preclinical investigations in animals and retrospective studies in patients have suggested that inhibition of platelets may improve the outcome of sepsis. In this study we investigated whether chronic antiplatelet therapy impacts on the presentation and outcome of sepsis, and the host response.

Methods

We performed a prospective observational study in 972 patients admitted with sepsis to the mixed intensive care units (ICUs) of two hospitals in the Netherlands between January 2011 and July 2013. Of them, 267 patients (27.5 %) were on antiplatelet therapy (95.9 % acetylsalicylic acid) before admission. To account for differential likelihoods of receiving antiplatelet therapy, a propensity score was constructed, including variables associated with use of antiplatelet therapy. Cox proportional hazards regression was used to estimate the association of antiplatelet therapy with mortality.

Results

Antiplatelet therapy was not associated with sepsis severity at presentation, the primary source of infection, causative pathogens, the development of organ failure or shock during ICU stay, or mortality up to 90 days after admission, in either unmatched or propensity-matched analyses. Antiplatelet therapy did not modify the values of 19 biomarkers providing insight into hallmark host responses to sepsis, including activation of the coagulation system, the vascular endothelium, the cytokine network, and renal function, during the first 4 days after ICU admission.

Conclusions

Pre-existing antiplatelet therapy is not associated with alterations in the presentation or outcome of sepsis, or the host response.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-015-4171-9) contains supplementary material, which is available to authorized users.

Antithrombotic and antiplatelet activities of pelargonidin in vivo and in vitro

Pelargonidin is a well-known red pigment found in plants, and has been reported as having important biological activities that are potentially beneficial for human health. However, the possible roles of pelargonidin as an anticoagulant and the underlying mechanism have not yet been elucidated. We tested the effect of pelargonidin and its glucoside-conjugated form, pelargonidin-3-glucoside, on the clotting times, such as activated partial thromboplastin time (aPTT) and prothrombin time (PT), and the activities and productions of thrombin and activated factor X (FXa). Furthermore, the effects of pelargonidin on the fibrin polymerization, platelet aggregation, and the ratio of plasminogen activator inhibitor-1 (PAI-1) to tissue plasminogen activator were determined. Pelargonidin, but not pelargonidin-3-glucoside, prolonged the aPTT and PT, and inhibited the activity and production of thrombin and FXa in human umbilical vein endothelial cells. Furthermore, pelargonidin inhibited thrombin-catalyzed fibrin polymerization and platelet aggregation and elicited anticoagulant effects in mice. In addition, pelargonidin significantly reduced PAI-1 to t-PA ratio. Collectively, these results indicate that the anthocyanin pelargonidin possesses antithrombotic activity, and can be beneficial in preventing thrombus formation, thus improving blood circulation.

A Dormant Microbial Component in the Development of Preeclampsia

Preeclampsia (PE) is a complex, multisystem disorder that remains a leading cause of morbidity and mortality in pregnancy. Four main classes of dysregulation accompany PE and are widely considered to contribute to its severity. These are abnormal trophoblast invasion of the placenta, anti-angiogenic responses, oxidative stress, and inflammation. What is lacking, however, is an explanation of how these themselves are caused. We here develop the unifying idea, and the considerable evidence for it, that the originating cause of PE (and of the four classes of dysregulation) is, in fact, microbial infection, that most such microbes are dormant and hence resist detection by conventional (replication-dependent) microbiology, and that by occasional resuscitation and growth it is they that are responsible for all the observable sequelae, including the continuing, chronic inflammation. In particular, bacterial products such as lipopolysaccharide (LPS), also known as endotoxin, are well known as highly inflammagenic and stimulate an innate (and possibly trained) immune response that exacerbates the inflammation further. The known need of microbes for free iron can explain the iron dysregulation that accompanies PE. We describe the main routes of infection (gut, oral, and urinary tract infection) and the regularly observed presence of microbes in placental and other tissues in PE. Every known proteomic biomarker of "preeclampsia" that we assessed has, in fact, also been shown to be raised in response to infection. An infectious component to PE fulfills the Bradford Hill criteria for ascribing a disease to an environmental cause and suggests a number of treatments, some of which have, in fact, been shown to be successful. PE was classically referred to as endotoxemia or toxemia of pregnancy, and it is ironic that it seems that LPS and other microbial endotoxins really are involved. Overall, the recognition of an infectious component in the etiology of PE mirrors that for ulcers and other diseases that were previously considered to lack one.

Peroxynitrite may affect fibrinolysis via the reduction of platelet-related fibrinolysis resistance and alteration of clot structure

We tested the hypothesis that in vitro peroxynitrite (ONOO(-), a product of activated inflammatory cells) may affect fibrinolysis in human blood through the reduction of platelet-related fibrinolysis resistance. It was found that ONOO(-) (25-300 µM) accelerated lysis of platelet-fibrin clots (in PRP) dose-dependently, whereas fibrinolysis of platelet-free clots was slightly inhibited by ≥ 1000 µM stressor. Concentrations of ONOO(-) affecting the lysis of platelet-rich clots, inhibited clot retraction (CR) in a dose-dependent manner. Thromboelastometry (ROTEM) measurements performed in PRP showed that treatment with ONOO(-) (threshold conc. 100 µM) prolongs clotting time, and reduces alpha angle, and clot formation velocity parameters indicating for reduced thrombin formation rate. In PRP, ONOO(-) (threshold conc. 100 µM) reduced the collagen-evoked exposure of phosphatidylserine (PS) on platelets' plasma membrane, the shedding of platelet-derived microparticles (PMP), and inhibited platelet-dependent thrombin generation (measured in artificial system), dose-dependently. As judged by confocal microscopy, similar ONOO(-) concentrations altered the architecture of clots formed in collagen-treated PRP. Clots formed in the presence of ONOO(-) were less dense and were composed of thicker fibers, which make them more susceptible to lysis. In platelet-depleted plasma, ONOO(-) (up to milimolar concentration) did not alter clot structure. Blockage of PS exposed on platelets resulted in an alteration of clot architecture toward more prone to lysis. ONOO(-), at lysis-affecting concentrations, inhibited the collagen-evoked secretion of fibrinolytic inhibitors from platelets. We conclude that physiologically relevant ONOO(-) concentrations may accelerate the lysis of platelet-fibrin clots predominantly via downregulation of platelet-related mechanisms including: platelet secretion, clot retraction, platelet procoagulant response, and the alteration in clot architecture associated with it.

Expression of HMGB1 in septic serum induces vascular endothelial hyperpermeability

The aim of the present study was to investigate the effects of high mobility group protein B1 (HMGB1), which is expressed in the serum of patients with sepsis, on vascular endothelial permeability. Sera from patients with sepsis were used to treat endothelial cells (ECs), and the effect on endothelial permeability was evaluated using immunofluorescence. The morphologies of endothelial cytoskeletal actin and vascular endothelial (VE)‑cadherin were assessed using laser scanning confocal microscopy. The protein expression levels of HMGB1, B‑cell lymphoma 2 (BCL‑2) and BCL‑2‑associated X protein (BAX) were detected using western blotting. EC apoptosis was measured using flow cytometry. The results demonstrated that HMGB1 was significantly expressed in the serum 24 h following the onset of sepsis, and the expression levels peaked at 48 h, which were sustained until 96 h post‑onset. Compared with the control group, treatment of the ECs with 20% septic serum in vitro significantly increased endothelial monolayer permeability (P<0.01), markedly induced transcellular filamentous (F)‑actin rearrangement with stress fiber formation, and resulted in the localization of VE‑cadherin fragmentations at the cell borders with increased gaps between ECs. Furthermore, flow cytometry showed that the apoptotic rate of ECs was significantly increased following treatment with septic serum. In addition, the expression levels of BAX were significantly increased, whereas the expression levels of BCL‑2 were significantly decreased. Pretreatment with an HMGBI inhibitor (ethyl pyruvate; 5 µM) 24 h prior to treatment with the septic serum attenuated the effects of septic serum treatment. Together, these findings suggested that treatment of ECs with sera from patients with sepsis may induce the loss of vascular endothelial monolayer integrity, elicit the formation of endothelial F‑actin stress fibers and initiate VE‑cadherin redistribution, which may be attributed to high levels of HMGB1 in the serum. This mechanism also appears to involve changes in the activation of BAX and BCL‑2, resulting in EC apoptosis.

Effect of Cholecalciferol Supplementation on Vitamin D Status and Cathelicidin Levels in Sepsis: A Randomized, Placebo-Controlled Trial

OBJECTIVES

To compare changes in vitamin D status and cathelicidin (LL-37) levels in septic ICU patients treated with placebo versus cholecalciferol.

DESIGN

Randomized, placebo-controlled, trial.

SETTING

Medical and surgical ICUs of a single teaching hospital in Boston, MA.

PATIENTS

Thirty adult ICU patients.

INTERVENTIONS

Placebo (n = 10) versus 200,000 IU cholecalciferol (n = 10) versus 400,000 IU cholecalciferol (n = 10), within 24 hours of new-onset severe sepsis or septic shock.

MEASUREMENTS AND MAIN RESULTS

Blood samples were obtained at baseline (day 1) and on days 3, 5, and 7, to assess total 25-hydroxyvitamin D, as well as vitamin D-binding protein and albumin to calculate bioavailable 25-hydroxyvitamin D. Plasma LL-37 and high-sensitivity C-reactive protein levels were also measured. At baseline, median (interquartile range) plasma 25-hydroxyvitamin D was 17 ng/mL (13-22 ng/mL) and peaked by day 5 in both intervention groups. Groups were compared using Kruskal-Wallis tests. Relative to baseline, on day 5, median change in biomarkers for placebo, 200,000 IU cholecalciferol, and 400,000 IU cholecalciferol groups, respectively, were as follows: 1) total 25-hydroxyvitamin D, 3% (-3% to 8%), 49% (30-82%), and 69% (55-106%) (p < 0.001); 2) bioavailable 25-hydroxyvitamin D, 4% (-8% to 7%), 45% (40-70%), and 96% (58-136%) (p < 0.01); and 3) LL-37: -17% (-9% to -23%), 4% (-10% to 14%), and 30% (23-48%) (p = 0.04). Change in high-sensitivity C-reactive protein levels did not differ between groups. A positive correlation was observed between bioavailable 25-hydroxyvitamin D and LL-37 (Spearman ρ = 0.44; p = 0.03) but not for total 25-hydroxyvitamin D and LL-37.

CONCLUSIONS

High-dose cholecalciferol supplementation rapidly and safely improves 25-hydroxyvitamin D and bioavailable 25-hydroxyvitamin D levels in patients with severe sepsis or septic shock. Changes in bioavailable 25-hydroxyvitamin D are associated with concomitant increases in circulating LL-37 levels. Larger trials are needed to verify these findings and to assess whether optimizing vitamin D status improves sepsis-related clinical outcomes.

Tissue plasminogen activator treatment of bilateral pulmonary emboli in a pediatric patient supported with a ventricular assist device

Bleeding and thrombosis are well-known potential complications of VAD support. We present a pediatric patient who developed massive bilateral pulmonary emboli while on BiVAD support that was successfully treated with intravenous tPA and bridged to heart transplant.

Atherosclerosis: a chronic inflammatory disease mediated by mast cells

Inflammation is a process that plays an important role in the initiation and progression of atherosclerosis and immune disease, involving multiple cell types, including macrophages, T-lymphocytes, endothelial cells, smooth muscle cells and mast cells. The fundamental damage of atherosclerosis is the atheromatous or fibro-fatty plaque which is a lesion that causes several diseases. In atherosclerosis the innate immune response, which involves macrophages, is initiated by the arterial endothelial cells which respond to modified lipoproteins and lead to Th1 cell subset activation and generation of inflammatory cytokines and chemoattractant chemokines. Other immune cells, such as CD4+ T inflammatory cells, which play a critical role in the development and progression of atherosclerosis, and regulatory T cells [Treg], which have a protective effect on the development of atherosclerosis are involved. Considerable evidence indicates that mast cells and their products play a key role in inflammation and atherosclerosis. Activated mast cells can have detrimental effects, provoking matrix degradation, apoptosis, and enhancement as well as recruitment of inflammatory cells, which actively contributes to atherosclerosis and plaque formation. Here we discuss the relationship between atherosclerosis, inflammation and mast cells.

Preprocedural Coagulation Studies in Pediatric Patients Undergoing Percutaneous Intervention for Appendiceal Abscesses

The literature reports poor correlation between coagulation screening and prediction of bleeding risk in children. Our aim is to determine whether there is a role for coagulation studies in children undergoing percutaneous intervention for appendiceal abscesses. A retrospective review of 1805 patients presenting with a diagnosis of appendicitis from September 2008 to September 2013 was performed. Patients presenting with appendiceal abscess who underwent percutaneous intervention were selected for further review (n = 131). A total of 76 patients (58%) had normal coagulation studies, whereas 55 (42%) had elevated values. An international normalized ratio ≥ 1.3 was found in 26 patients. Patients with normal coagulation values had an incidence of bleeding of 1.3 per cent. In the abnormal coagulation group, 8 patients received fresh frozen plasma before intervention, whereas 47 did not. There was one hematoma noted in each group with an incidence of bleeding of 3.6 per cent. The overall incidence of hematoma was 2.3 per cent with no significant difference in bleeding risk between the normal and abnormal coagulation groups. In conclusion, although many patients are found to have elevated coagulation studies, most do not have bleeding complications after intervention. There is poor correlation between coagulation screening and postprocedural outcomes evidenced by the low risk of bleeding.

Extracellular signal-regulated kinase 5 promotes acute cellular and systemic inflammation

Inflammatory critical illness is a syndrome that is characterized by acute inflammation and organ injury, and it is triggered by infections and noninfectious tissue injury, both of which activate innate immune receptors and pathways. Although reports suggest an anti-inflammatory role for the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase 5 (ERK5), we previously found that ERK5 mediates proinflammatory responses in primary human cells in response to stimulation of Toll-like receptor 2 (TLR2). We inhibited the kinase activities and reduced the abundances of ERK5 and MEK5, a MAPK kinase directly upstream of ERK5, in primary human vascular endothelial cells and monocytes, and found that ERK5 promoted inflammation induced by a broad range of microbial TLR agonists and by the proinflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Furthermore, we found that inhibitors of MEK5 or ERK5 reduced the plasma concentrations of proinflammatory cytokines in mice challenged with TLR ligands or heat-killed Staphylococcus aureus, as well as in mice that underwent sterile lung ischemia-reperfusion injury. Finally, we found that inhibition of ERK5 protected endotoxemic mice from death. Together, our studies support a proinflammatory role for ERK5 in primary human endothelial cells and monocytes, and suggest that ERK5 is a potential therapeutic target in diverse disorders that cause inflammatory critical illness.

Inhibition of COX-1 attenuates the formation of thromboxane A2 and ameliorates the acute decrease in glomerular filtration rate in endotoxemic mice

Thromboxane (Tx) A2 has been suggested to be involved in the development of sepsis-induced acute kidney injury (AKI). Therefore, we investigated the impact of cyclooxygenase (COX)-1 and COX-2 activity on lipopolysaccharide (LPS)-induced renal TxA2 formation, and on endotoxemia-induced AKI in mice. Injection of LPS (3 mg/kg ip) decreased glomerular filtration rate (GFR) and the amount of thrombocytes to ∼50% of basal values after 4 h. Plasma and renocortical tissue levels of TxB2 were increased ∼10- and 1.7-fold in response to LPS, respectively. The COX-1 inhibitor SC-560 attenuated the LPS-induced fall in GFR and in platelet count to ∼75% of basal levels. Furthermore, SC-560 abolished the increase in plasma and renocortical tissue levels of TxB2 in response to LPS. The COX-2 inhibitor SC-236 further enhanced the LPS-induced decrease in GFR to ∼40% of basal values. SC-236 did not alter thrombocyte levels nor the LPS-induced increase in plasma and renocortical tissue levels of TxB2. Pretreatment with clopidogrel inhibited the LPS-induced drop in thrombocyte count, but did not attenuate the LPS-induced decrease in GFR and the increase in plasma TxB2 levels. This study demonstrates that endotoxemia-induced TxA2 formation depends on the activity of COX-1. Our study further indicates that the COX-1 inhibitor SC-560 has a protective effect on the decrease in renal function in response to endotoxin. Therefore, our data support a role for TxA2 in the development of AKI in response to LPS.

Metformin suppresses intrahepatic coagulation activation in mice with lipopolysaccharide/D‑galactosamine‑induced fulminant hepatitis

Metformin is a widely‑used antidiabetic drug with hypoglycemic activity and previously described anti‑inflammatory properties. Previous studies have demonstrated that metformin attenuates endotoxic hepatitis, however the mechanisms remain unclear. Inflammation and coagulation are closely associated pathological processes, therefore the potential effects of metformin on key steps in activation of the coagulation system were further investigated in endotoxic hepatitis induced by lipopolysaccharide/D‑galactosamine (LPS/D‑Gal). The current study demonstrated that treatment with metformin significantly suppressed the upregulation of tissue factor and plasminogen activator inhibitor‑1 in LPS/D‑Gal‑exposed mice. In addition, a reduction in the expression of interleukin 6 and inhibition of nuclear translocation of nuclear factor‑κB were observed. These data indicate that the LPS/D‑Gal‑induced elevation of the stable protein level of hypoxia inducible factor 1α, the mRNA level of erythropoietin, vascular endothelial growth factor and matrix metalloproteinase‑3, and the hepatic level of lactic acid were also suppressed by metformin. The current study indicates that the suppressive effects of metformin on inflammation‑induced coagulation may be an additional mechanism underlying the hepatoprotective effects of metformin in mice with LPS/D‑Gal‑induced fulminant hepatitis.

Prevalence and significance of two major inherited thrombophilias in infective endocarditis

The pathogenesis of infective endocarditis (IE) involves activation of the haemostasis system at the site of endocardial defects. Whether prothrombotic conditions are associated with IE by enhancing early vegetation formation is unknown. In this study, we assess the prevalence and clinical significance of two major conditions associated with thrombophilia in patients with IE. Mutations G20210A of the prothrombin (PTH) gene and G1691A of factor V (FV Leiden) gene were studied by means of allele-specific polymerase chain reaction in 203 IE patients, 175 valvular heart disease (VHD) patients and 200 blood donors (BD). IE patients show higher cumulative frequencies of mutated alleles of PTH and FV Leiden [6.4 vs 3.25 %; OR 2.03 (95 % CI 0.97-3.66); p = 0.047] compared to BD, but not VHD. Device-related IE is enriched with FV Leiden, and prosthetic valve IE with PTH mutations (allele frequency 8.3 vs 2.2 % in native valve IE; p = 0.021). Vegetation size and embolic complications are not influenced by the examined thrombophilias. A trend for a higher mortality was observed in IE patients with any of the two thrombophilias studied. Our data do not support a role for factor V Leiden and G20210A prothrombin gene mutations in the susceptibility to IE. Whether any of these genetic polymorphisms play a role in a specific subtype of IE needs to be re-examined in larger studies.

Flow-driven assembly of VWF fibres and webs in in vitro microvessels

Several systemic diseases, including thrombotic thrombocytopenic purpura, manifest much of their pathology through activation of endothelium and thrombotic occlusion of small blood vessels, often leading to multi-organ failure and death. Modelling these diseases is hampered by the complex three-dimensional architecture and flow patterns of the microvasculature. Here, we employ engineered microvessels of complex geometry to examine the pathological responses to endothelial activation. Our most striking finding is the capacity of endothelial-secreted von Willebrand factor (VWF) to assemble into thick bundles or complex meshes, depending on the vessel geometry and flow characteristics. Assembly is greatest in vessels of diameter ≤300 μm, with high shear stress or strong flow acceleration, and with sharp turns. VWF bundles and webs bind platelets, leukocytes and erythrocytes, obstructing blood flow and sometimes shearing passing erythrocytes. Our findings uncover the biophysical requirements for initiating microvascular thrombosis and suggest mechanisms for the onset and progression of microvascular diseases.

3D microvessels with complex geometries and intact endothelium can be built in vitro. Using these engineered microvessels, here the authors show that the generation of the pathologic meshwork of the blood protein von Willebrand factor is affected by vessel architecture, flow and the proteolytic activity of ADAMTS13.

Individuality, phenotypic differentiation, dormancy and 'persistence' in culturable bacterial systems: commonalities shared by environmental, laboratory, and clinical microbiology

For bacteria, replication mainly involves growth by binary fission. However, in a very great many natural environments there are examples of phenotypically dormant, non-growing cells that do not replicate immediately and that are phenotypically 'nonculturable' on media that normally admit their growth. They thereby evade detection by conventional culture-based methods. Such dormant cells may also be observed in laboratory cultures and in clinical microbiology. They are usually more tolerant to stresses such as antibiotics, and in clinical microbiology they are typically referred to as 'persisters'. Bacterial cultures necessarily share a great deal of relatedness, and inclusive fitness theory implies that there are conceptual evolutionary advantages in trading a variation in growth rate against its mean, equivalent to hedging one's bets. There is much evidence that bacteria exploit this strategy widely. We here bring together data that show the commonality of these phenomena across environmental, laboratory and clinical microbiology. Considerable evidence, using methods similar to those common in environmental microbiology, now suggests that many supposedly non-communicable, chronic and inflammatory diseases are exacerbated (if not indeed largely caused) by the presence of dormant or persistent bacteria (the ability of whose components to cause inflammation is well known). This dormancy (and resuscitation therefrom) often reflects the extent of the availability of free iron. Together, these phenomena can provide a ready explanation for the continuing inflammation common to such chronic diseases and its correlation with iron dysregulation. This implies that measures designed to assess and to inhibit or remove such organisms (or their access to iron) might be of much therapeutic benefit.

Individuality, phenotypic differentiation, dormancy and 'persistence' in culturable bacterial systems: commonalities shared by environmental, laboratory, and clinical microbiology

For bacteria, replication mainly involves growth by binary fission. However, in a very great many natural environments there are examples of phenotypically dormant, non-growing cells that do not replicate immediately and that are phenotypically 'nonculturable' on media that normally admit their growth. They thereby evade detection by conventional culture-based methods. Such dormant cells may also be observed in laboratory cultures and in clinical microbiology. They are usually more tolerant to stresses such as antibiotics, and in clinical microbiology they are typically referred to as 'persisters'. Bacterial cultures necessarily share a great deal of relatedness, and inclusive fitness theory implies that there are conceptual evolutionary advantages in trading a variation in growth rate against its mean, equivalent to hedging one's bets. There is much evidence that bacteria exploit this strategy widely. We here bring together data that show the commonality of these phenomena across environmental, laboratory and clinical microbiology. Considerable evidence, using methods similar to those common in environmental microbiology, now suggests that many supposedly non-communicable, chronic and inflammatory diseases are exacerbated (if not indeed largely caused) by the presence of dormant or persistent bacteria (the ability of whose components to cause inflammation is well known). This dormancy (and resuscitation therefrom) often reflects the extent of the availability of free iron. Together, these phenomena can provide a ready explanation for the continuing inflammation common to such chronic diseases and its correlation with iron dysregulation. This implies that measures designed to assess and to inhibit or remove such organisms (or their access to iron) might be of much therapeutic benefit.

Gut Microbiota and Immunity: Possible Role in Sudden Infant Death Syndrome

The gut microbiome influences the development of the immune system of young mammals; the establishment of a normal gut microbiome is thought to be important for the health of the infant during its early development. As the role of bacteria in the causation of sudden infant death syndrome (SIDS) is backed by strong evidence, the balance between host immunity and potential bacterial pathogens is likely to be pivotal. Bacterial colonization of the infant colon is influenced by age, mode of delivery, diet, environment, and antibiotic exposure. The gut microbiome influences several systems including gut integrity and development of the immune system; therefore, gut microflora could be important in protection against bacteria and/or their toxins identified in SIDS infants. The aims of the review are to explore (1) the role of the gut microbiome in relation to the developmentally critical period in which most SIDS cases occur; (2) the mechanisms by which the gut microbiome might induce inflammation resulting in transit of bacteria from the lumen into the bloodstream; and (3) assessment of the clinical, physiological, pathological, and microbiological evidence for bacteremia leading to the final events in SIDS pathogenesis.

Platelet and endothelial cell P-selectin are required for host defense against Klebsiella pneumoniae-induced pneumosepsis

BACKGROUND

Sepsis is associated with activation of platelets and endothelial cells accompanied by enhanced P-selectin surface expression. Both platelet- and endothelial P-selectin have been associated with leukocyte recruitment and induction of inflammatory alterations. Klebsiella (K.) pneumoniae is a common human sepsis pathogen, particularly in the context of pneumonia.

METHODS

Wild-type (WT) and P-selectin-deficient (Selp(-/-) ) mice or bone marrow chimeric mice were infected with K. pneumoniae via the airways to induce pneumosepsis. Mice were sacrificed during early (12 h after infection) or late-stage (44 h) sepsis for analyses, or followed in a survival study.

RESULTS

Selp(-/-) mice displayed 10-1000-fold higher bacterial burdens in the lungs, blood and distant organs during late-stage sepsis. P-selectin deficiency did not influence leukocyte recruitment to the lungs, but was associated with decreased platelet-monocyte complexes and increased cytokine release. Bone marrow transfer studies revealed a role for both platelet and endothelial cell P-selectin as mice deficient in platelet or endothelial cell P-selectin displayed an intermediate phenotype in bacterial loads and survival compared with full wild-type or full knockout control mice.

CONCLUSION

Both platelet and endothelial cell P-selectin contribute to host defense during Klebsiella pneumosepsis.

Lysosome and Cytoskeleton Pathways Are Robustly Enriched in the Blood of Septic Patients: A Meta-Analysis of Transcriptomic Data

Background. Sepsis is a leading cause of mortality in intensive care units worldwide. A better understanding of the blood systems response to sepsis should expedite the identification of biomarkers for early diagnosis and therapeutic interventions. Methods. We analyzed microarray studies whose data is available from the GEO repository and which were performed on the whole blood of septic patients and normal controls. Results. We identified 6 cohorts consisting of 450 individuals (sepsis = 323, control = 127) providing genome-wide messenger RNA (mRNA) expression data. Through meta-analysis we found the “Lysosome” and “Cytoskeleton” pathways were upregulated in human sepsis patients relative to controls, in addition to previously known signaling pathways (including MAPK, TLR). The key regulatory genes in the “Lysosome” pathway include lysosomal acid hydrolases (e.g., protease cathepsin A, D) as well as the major (LAMP1, 2) and minor (SORT1, LAPTM4B) membrane proteins. In contrast, pathways related to “Ribosome”, “Spliceosome” and “Cell adhesion molecules” were found to be downregulated, along with known pathways for immune dysfunction. Overall, our study revealed distinct mRNA activation profiles and protein-protein interaction networks in blood of human sepsis. Conclusions. Our findings suggest that aberrant mRNA expression in the lysosome and cytoskeleton pathways may play a pivotal role in the molecular pathobiology of human sepsis.

'Sepsis-related anemia' is absent at hospital presentation; a retrospective cohort analysis

BACKGROUND

Anemia is a common feature during sepsis that occurs due to iatrogenic blood loss, depression of serum iron levels and erythropoietin production, and a decreased lifespan of erythrocytes. However, these mechanisms are unlikely to play a role in anemia at the start of sepsis. Moreover, sequestration of fluids, renal failure and increase of intravascular space may additionally influence the change in hemoglobin concentration during intravenous fluid administration in the acute phase of sepsis.

METHODS

In this retrospective study, patients who were admitted acutely to the Intensive Care Unit (ICU) were included. Patients who fulfilled the international criteria for severe sepsis or septic shock were included in the sepsis group (S-group). The remaining patients were allocated to the control group (C-group). Laboratory data from blood samples taken at first presentation to the hospital and at admission to the ICU, the amount of intravenous fluid administration and length of stay in the emergency department were collected and tested for significant differences between groups.

RESULTS

The difference in hemoglobin concentration between the S-group (n = 296) and C-group (n = 320) at first presentation in hospital was not significant (8.8 ± 1.2 versus 8.9 ± 1.2 mmol/l, respectively, p = 0.07). The reduction in hemoglobin concentration from the first presentation at the emergency department to ICU admission was significantly greater in the S-group compared to the C-group (1 [0.5-1.7] versus 0.5 [0.1-1.1] mmol/l, (p < 0.001)). Spearman rho correlation coefficients between the reduction in hemoglobin concentration and the amount of intravenous fluids administered or the creatinine level in the emergency department were significant (0.3 and 0.4, respectively, p < 0.001). In a multivariate regression analysis, creatinine, the amount of fluid administration and the presence of sepsis remained independently associated.

CONCLUSIONS

Prior to in-hospital intravenous fluid administration, there is no significant difference in hemoglobin concentration between acute septic patients and acutely ill controls. Within several hours after hospital admission, there is a significant reduction in hemoglobin concentration, not only associated with the amount of intravenous fluids administered and the creatinine level, but also independently with sepsis itself.

Association between biomarkers of endothelial injury and hypocoagulability in patients with severe sepsis: a prospective study

Introduction

Patients with severe sepsis often present with concurrent coagulopathy, microcirculatory failure and evidence of vascular endothelial activation and damage. Given the critical role of the endothelium in balancing hemostasis, we investigated single-point associations between whole blood coagulopathy by thrombelastography (TEG) and plasma/serum markers of endothelial activation and damage in patients with severe sepsis.

Methods

A post-hoc multicenter prospective observational study in a subgroup of 184 patients from the Scandinavian Starch for Severe Sepsis/Septic Shock (6S) Trial. Study patients were admitted to two Danish intensive care units. Inclusion criteria were severe sepsis, pre-intervention whole blood TEG measurement and a plasma/serum research sample available from baseline (pre-intervention) for analysis of endothelial-derived biomarkers. Endothelial-derived biomarkers were measured in plasma/serum by enzyme-linked immunosorbent assay (syndecan-1, thrombomodulin, protein C (PC), tissue-type plasminogen activator and plasminogen activator inhibitor-1). Pre-intervention TEG, functional fibrinogen (FF) and laboratory and clinical data, including mortality, were retrieved from the trial database.

Results

Most patients presented with septic shock (86%) and pulmonary (60%) or abdominal (30%) focus of infection. The median (IQR) age was 67 years (59 to 75), and 55% were males. The median SOFA and SAPS II scores were 8 (6 to 10) and 56 (41 to 68), respectively, with 7-, 28- and 90-day mortality rates being 21%, 39% and 53%, respectively. Pre-intervention (before treatment with different fluids), TEG reaction (R)-time, angle and maximum amplitude (MA) and FF MA all correlated with syndecan-1, thrombomodulin and PC levels. By multivariate linear regression analyses, higher syndecan-1 and lower PC were independently associated with TEG and FF hypocoagulability at the same time-point: 100 ng/ml higher syndecan-1 predicted 0.64 minutes higher R-time (SE 0.25), 1.78 mm lower TEG MA (SE 0.87) and 0.84 mm lower FF MA (SE 0.42; all P <0.05), and 10% lower protein C predicted 1.24 mm lower TEG MA (SE 0.31).

Conclusions

In our cohort of patients with severe sepsis, higher circulating levels of biomarkers of mainly endothelial damage were independently associated with hypocoagulability assessed by TEG and FF. Endothelial damage is intimately linked to coagulopathy in severe sepsis.

Trial registration

Clinicaltrials.gov number: NCT00962156. Registered 13 July 2009.