Multiple organ failure in sepsis: prognosis and role of systemic inflammatory response:

Lipopolysaccharide Induces Human Pulmonary Micro-Vascular Endothelial Apoptosis via the YAP Signaling Pathway

Gram-negative bacterial lipopolysaccharide (LPS) induces a pathologic increase in lung vascular leakage under septic conditions. LPS-induced human pulmonary micro-vascular endothelial cell (HPMEC) apoptosis launches and aggravates micro-vascular hyper-permeability and acute lung injury (ALI). Previous studies show that the activation of intrinsic apoptotic pathway is vital for LPS-induced EC apoptosis. Yes-associated protein (YAP) has been reported to positively regulate intrinsic apoptotic pathway in tumor cells apoptosis. However, the potential role of YAP protein in LPS-induced HPMEC apoptosis has not been determined. In this study, we found that LPS-induced activation and nuclear accumulation of YAP accelerated HPMECs apoptosis. LPS-induced YAP translocation from cytoplasm to nucleus by the increased phosphorylation on Y357 resulted in the interaction between YAP and transcription factor P73. Furthermore, inhibition of YAP by small interfering RNA (siRNA) not only suppressed the LPS-induced HPMEC apoptosis but also regulated P73-mediated up-regulation of BAX and down-regulation of BCL-2. Taken together, our results demonstrated that activation of the YAP/P73/(BAX and BCL-2)/caspase-3 signaling pathway played a critical role in LPS-induced HPMEC apoptosis. Inhibition of the YAP might be a potential therapeutic strategy for lung injury under sepsis.

Dose-Dependent Effect of Granulocyte Transfusions in Hematological Patients with Febrile Neutropenia

It is still under debate whether granulocyte transfusions (GTs) substantially increase survival in patients with febrile neutropenia. We retrospectively examined data relative to 96 patients with hematological malignancies receiving 491 GTs during 114 infectious episodes (IE). Patients were grouped according to the median doses of granulocytes transfused during the infectious episode (low-dose group: <1.5-x10⁸ cells/Kg; standard-dose group: 1.5–3.0x10⁸ cells/Kg and high-dose group: >3.0x10⁸ cells/Kg). The impact of clinical, microbiological and GT-related variables on the infection-related mortality (IRM) was investigated. The IRM was not influenced by the number of GTs or by the total amount of granulocytes received, whereas a dose-related effect of the median dose received for IE was detected at univariate analysis (IRM of 18.4% in the standard-dose group, 44.4% in the low-dose group and 48.4% in the high-dose group, p = 0.040) and confirmed at multivariate analysis (OR 3.7, IC 95% 1.5–8.9; 0.004 for patients not receiving standard doses of GTs). Moreover, patients receiving GTs at doses lower or greater than standard had increased risk for subsequent ICU admission and reduced overall survival. The dose-related effect of GTs was confirmed in bacterial but not in fungal infections. Preliminary findings obtained from a subgroup of patients candidate to GTs revealed that levels of inflammatory response mediators increase in a dose-related manner after GTs, providing a possible explanation for the detrimental effect exerted by high-dose transfusions. GTs can constitute a valuable tool to improve the outcome of infections in neutropenic patients, provided that adequate recipient-tailored doses are supplied. Further investigations of the immunomodulatory effects of GTs are recommended.

Protective effect of recombinant Trichinella 53-kDa protein in sepsis and the effect on macrophages

The survival rate of the recombinant Trichinella 53-kDa protein infected by the cecal ligation and puncture (CLP) model of sepsis in rats and the expression difference of macrophages were analyzed. Eighteen clean SD rats were selected for the present study. The rats were divided into the sham operation (n=5), control (n=5) and experimental (n=8) groups. The rats in the sham operation group underwent cecum division and suture with routine therapy for cure. The rats in the control and experimental groups were placed in the CLP model of sepsis in rats. The experimental group was administered recombinant Trichinella 53-kDa protein in advance, and the control group was administered the same dose of placebo. The survival rate of the rats within 6 and 12 h, the macrophage expression ratio, and the differences of the expression levels Th1-type cytokines IFN-γ and tumor necrosis factor (TNF)-α, and the Th2 type cytokines interleukin-4 (IL-4) and IL-13 were analyzed. The survival rate of rats in the experimental group was higher than that of the control group with a statistically significant difference (P<0.05). The expression ratio of the macrophages received from the different handling methods of the rats in the experimental group was higher than that of the control group. The difference was statistically significant (P<0.05). The expression levels of the Th1-type cytokines IFN-γ and TNF-α of the rats in the experimental group was higher than that of the control group, while the expression level of the Th2-type cytokines IL-4 and IL-13 was higher than that of the control group. The difference was statistically significant (P<0.05). In conclusion, recombinant Trichinella 53-kDa protein can increase the survival rate following infection with CLP sepsis, which may be associated with the improvement of the macrophages and the adjustment of the expression of Th2 cytokines.

Calcitriol inhibits tumor necrosis factor alpha and macrophage inflammatory protein-2 during lipopolysaccharide-induced acute lung injury in mice

Acute lung injury is a common complication of sepsis in intensive care unit patients with an extremely high mortality. The present study investigated the effects of calcitriol, the active form of vitamin D, on tumor necrosis factor alpha (TNF-α) and macrophage inflammatory protein-2 (MIP-2) in sepsis-induced acute lung injury. Mice were intraperitoneally (i.p.) injected with lipopolysaccharide (LPS, 1.0mg/kg) to establish the animal model of sepsis-induced acute lung injury. Some mice were i.p. injected with calcitriol (1.0μg/kg) before LPS injection. An obvious infiltration of inflammatory cells in the lungs was observed beginning at 1h after LPS injection. Correspondingly, TNF-α and MIP-2 in sera and lung homogenates were markedly elevated in LPS-treated mice. Interestingly, calcitriol obviously alleviated LPS-induced infiltration of inflammatory cells in the lungs. Moreover, calcitriol markedly attenuated LPS-induced elevation of TNF-α and MIP-2 in sera and lung homogenates. Further analysis showed that calcitriol repressed LPS-induced p38 mitogen-activated protein kinase (MAPK) and protein kinase B (Akt) phosphorylation. In addition, calcitriol blocked LPS-induced nuclear translocation of nuclear factor kappa B (NF-κB) p65 and p50 subunit in the lungs. Taken together, these results suggest that calcitriol inhibits inflammatory cytokines production in LPS-induced acute lung injury.

Study of Aetiology and Outcome in Acute Febrile Illness Patients with Multiple Organ Dysfunction Syndrome

INTRODUCTION

Acute febrile illness with Multi Organ Dysfunction Syndrome (MODS) carries significant morbidity and mortality despite standard therapy in intensive care settings. Infections are the most common cause of MODS followed by polytrauma. Present study was undertaken in medical intensive care units of a tertiary hospital to study the aetiology and outcome among patients with acute febrile illness developing MODS.

AIM

1) To study the aetiology of acute febrile illness in patients developing MODS. 2) To study the final outcome among these patients.

MATERIALS AND METHODS

The present study was conducted at a tertiary care hospital in Mysuru, Karnataka, India, over a period of 6 months from July 2013 to December 2013. The Institutional Ethics Committee Approval (IEC) was obtained before the commencement of the study. A total of 213 cases admitted in intensive care unit with acute febrile illness with two or more organ dysfunction were screened for the inclusion and exclusion criterias.

RESULTS

A total of 213 cases of acute febrile illness with one or more organ dysfunction were screened. Of the screened patients 75 patients were finally included in the study out of which 46 (61.3%) patients were males and 29 (38.7%) patients were females. Aetiology for acute febrile illness with MODS could be established in 49 (65.3%) patients and it was obscure in 26 (34.7%) patients despite repeated investigations. Dengue infection (29.3%) was the commonest cause of febrile illness with MODS followed by leptospirosis (22.7%). Majority of these patients had haematological derangements (78.7%) and liver function test abnormalities (68%). Out of these 75 cases, 54 (72%) patients recovered completely and 21 (28%) patients died. Among males (N=46), 35 (76.1%) patients recovered and 11 (23.9%) patients died where as among females (N=29), 19 (65.5%) patients recovered and 10 (34.5%) patients died. Mortality was proportionate with the number of organ dysfunction, especially Central Nervous System (CNS) involvement.

CONCLUSION

Incidence of febrile illness with MODS is more prevalent in males but the outcome appears poorer among females. The diagnosis remained obscure in a sizable proportion of these patients. Prognosis was inversely dependent on the number of organs involved especially with CNS manifestations.

Shikonin induces apoptosis of lung cancer cells via activation of FOXO3a/EGR1/SIRT1 signaling antagonized by p300

Shikonin derivatives exert powerful cytotoxic effects including induction of apoptosis. Here, we demonstrate the cytotoxic efficacy of shikonin in vivo in xenograft models, which did not affect body weight as well as its reduction of cell viability in vitro using several non-small cell lung cancer (NSCLC) cell lines. We found that inhibition of AKT by shikonin activated the forkhead box (FOX)O3a/early growth response protein (EGR)1 signaling cascade and enhanced the expression of the target gene Bim, leading to apoptosis in lung cancer cells. Overexpression of wild-type or a constitutively active mutant of FOXO3a enhanced shikonin-induced Bim expression. The NAD⁺-dependent histone deacetylase sirtuin (SIRT)1 amplified the pro-apoptotic effect by deacetylating FOXO3a, which induced EGR1 binding to the Bim promoter and activated Bim expression. Meanwhile, PI3K/AKT activity was enhanced, whereas that of FOXO3a was reduced and p300 was upregulated by treatment with a sublethal dose of shikonin. FOXO3a acetylation was enhanced by p300 overexpression, while shikonin-induced Bim expression was suppressed by p300 overexpression, which promoted cell survival. FOXO3a acetylation was increased by p300 overexpression and treatment with SIRT1 inhibitor, improving cell survival. In addition, shikonin-induced FOXO3a nuclear localization was blocked by AKT activation and SIRT1 inhibition, which blocked Bim expression and conferred resistance to the cytotoxic effects of shikonin. The EGR1 increase induced by shikonin was restored by pretreatment with SIRT1 inhibitor. These results suggest that shikonin induces apoptosis in some lung cancer cells via activation of FOXO3a/EGR1/SIRT1 signaling, and that AKT and p300 negatively regulate this process via Bim upregulation.

A novel imidazopyridine derivative, X22, attenuates sepsis-induced lung and liver injury by inhibiting the inflammatory response in vitro and in vivo

Sepsis remains a leading cause of death worldwide. Despite years of extensive research, effective drugs to treat sepsis in the clinic are lacking. In this study, we found a novel imidazopyridine derivative, X22, which has powerful anti-inflammatory activity. X22 dose-dependently inhibited lipopolysaccharide (LPS)-induced proinflammatory cytokine production in mouse primary peritoneal macrophages and RAW 264.7 macrophages. X22 also downregulated the LPS-induced proinflammatory gene expression in vitro. In vivo, X22 exhibited a significant protection against LPS-induced death. Pretreatment or treatment with X22 attenuated the sepsis-induced lung and liver injury by inhibiting the inflammatory response. In addition, X22 showed protection against LPS-induced acute lung injury. We additionally found that pretreatment with X22 reduced the inflammatory pain in the acetic acid and formalin models and reduced the dimethylbenzene-induced ear swelling and acetic acid-increased vascular permeability. Together, these data confirmed that X22 has multiple anti-inflammatory effects and may be a potential therapeutic option in the treatment of inflammatory diseases.

Targeting cytokines as a treatment for patients with sepsis: A lost cause or a strategy still worthy of pursuit?

Despite often knowing the aetiology of sepsis and its clinical course there has not been the anticipated advances in treatment strategies. Cytokines are influential mediators of immune/inflammatory reactions and in patients with sepsis high circulating levels are implicated in the onset and perpetuation of organ failure. Antagonising the activities of pro-inflammatory cytokines enhances survival in animal models of sepsis but, so far, such a therapeutic strategy has not improved patient outcome. This article addresses the questions of why encouraging laboratory findings have failed to be translated into successful treatments of critically ill patients and whether modifying cytokine activity still remains a promising avenue for therapeutic advance in severe sepsis. In pursuing this task we have selected reports that we believe provide an incisive, critical and balanced view of the topic.

Prediction of multiple organ dysfunction syndrome complicating acute myocardial infarction on the basis of comorbidities on admission

BACKGROUND

Acute myocardial infarction (AMI) can be complicated by multiple organ dysfunction syndrome (MODS), but the exact influence of MODS on AMI remains unclear.

METHODS

This was a retrospective study of 6674 Chinese patients with AMI. The impact of MODS was assessed using the Cox proportional hazard model. Using the occurrence of MODS as the outcome, a prediction model was developed using the factors identified by logistic regression analysis and analyzed using receiving operator characteristic curves.

RESULTS

Of 6674 patients with AMI, 83 (1.2%) progressed to MODS. MODS independently predicted the risk of 30-day in-hospital mortality [hazard ratio, 2.3; 95% confidence interval (95% CI), 1.7-3.2; P<0.001]. Advanced age [odds ratio (OR), 2.76; 95% CI, 1.26-6.03; P=0.011 for age 65-74 years; OR, 4.85; 95% CI, 2.96-7.93; P<0.001 for age ≥75 years), pneumonia (OR, 4.27; 95% CI, 2.68-6.81; P<0.001), and chronic renal failure (OR, 2.09; 95% CI, 1.09-4.01; P=0.027) were associated independently with MODS. The area under the receiving operator characteristic curve for the predictive model was 0.802, indicating a good predictive value.

CONCLUSION

MODS can predict the worst severity of AMI. Using common clinical variables, it is possible to identify patients with AMI who are at high risk of MODS. Additional studies are necessary to confirm this model.

Discovery of new MD2 inhibitor from chalcone derivatives with anti-inflammatory effects in LPS-induced acute lung injury

Acute lung injury (ALI) is a life-threatening acute inflammatory disease with limited options available for therapy. Myeloid differentiation protein 2, a co-receptor of TLR4, is absolutely required for TLR4 sense LPS, and represents an attractive target for treating severe inflammatory diseases. In this study, we designed and synthesized 31 chalcone derivatives that contain the moiety of (E)-4-phenylbut-3-en-2-one, which we consider the core structure of current MD2 inhibitors. We first evaluated the anti-inflammatory activities of these compounds in MPMs. For the most active compound 20, we confirmed that it is a specific MD2 inhibitor through a series of biochemical experiments and elucidated that it binds to the hydrophobic pocket of MD2 via hydrogen bonds with Arg⁹⁰ and Tyr¹⁰² residues. Compound 20 also blocked the LPS-induced activation of TLR4/MD2 -downstream pro-inflammatory MAPKs/NF-κB signaling pathways. In a rat model with ALI induced by intracheal LPS instillation, administration with compound 20 exhibited significant protective effect against ALI, accompanied by the inhibition of TLR4/MD2 complex formation in lung tissues. Taken together, the results of this study suggest the specific MD2 inhibitor from chalcone derivatives we identified is a potential candidate for treating acute inflammatory diseases.

Simvastatin and a Plant Galactolipid Protect Animals from Septic Shock by Regulating Oxylipin Mediator Dynamics through the MAPK-cPLA2 Signaling Pathway

Sepsis remains a major medical issue despite decades of research. Identification of important inflammatory cascades and key molecular mediators are crucial for developing intervention and prevention strategies. In this study, we conducted a comparative oxylipin metabolomics study to gain a comprehensive picture of lipid mediator dynamics during the initial hyperinflammatory phase of sepsis, and demonstrated, in parallel, the efficacy of simvastatin and plant galactolipid, 1,2-di-O-α-linolenoyl-3-O-β-galactopyranosyl-sn-glycerol (dLGG) in the homeostatic regulation of the oxylipin metabolome using a lipopolysaccharide (LPS)-induced sepsis C57BL/6J mouse model. LPS increased the systemic and organ levels of proinflammatory metabolites of linoleic acid including leukotoxin diols (9-,10-DHOME, 12-,13-DHOME) and octadecadienoic acids (9-HODE and 13-HODE) and arachidonic acid-derived prostanoid, PGE2, and hydroxyeicosatetraenoic acids (8-, 12- and 15-HETE). Treatment with either compound decreased the levels of proinflammatory metabolites and elevated proresolution lipoxin A₄, 5(6)-EET, 11(12)-EET and 15-deoxy-PGJ₂. dLGG and simvastatin ameliorated the effects of LPS-induced mitogen-activated protein kinase (MAPK)-dependent activation of cPLA₂, cyclooxygenase-2, lipoxygenase, cytochrome P450 and/or epoxide hydrolase lowered systemic TNF-α and IL-6 levels and aminotransferase activities and decreased organ-specific infiltration of inflammatory leukocytes and macrophages, and septic shock-induced multiple organ damage. Furthermore, both dLGG and simvastatin increased the survival rates in the cecal ligation and puncture (CLP) sepsis model. This study provides new insights into the role of oxylipins in sepsis pathogenesis and highlights the potential of simvastatin and dLGG in sepsis therapy and prevention.

Inflammatory Kidney and Liver Tissue Response to Different Hydroxyethylstarch (HES) Preparations in a Rat Model of Early Sepsis

Background

Tissue hypoperfusion and inflammation in sepsis can lead to organ failure including kidney and liver. In sepsis, mortality of acute kidney injury increases by more than 50%. Which type of volume replacement should be used is still an ongoing debate. We investigated the effect of different volume strategies on inflammatory mediators in kidney and liver in an early sepsis model.

Material and Methods

Adult male Wistar rats were subjected to sepsis by cecal ligation and puncture (CLP) and assigned to three fluid replenishment groups. Animals received 30mL/kg of Ringer’s lactate (RL) for 2h, thereafter RL (75mL/kg), hydroxyethyl starch (HES) balanced (25mL/kg), containing malate and acetate, or HES saline (25mL/kg) for another 2h. Kidney and liver tissue was assessed for inflammation. In vitro rat endothelial cells were exposed to RL, HES balanced or HES saline for 2h, followed by stimulation with tumor necrosis factor-α (TNF-α) for another 4h. Alternatively, cells were exposed to malate, acetate or a mixture of malate and acetate, reflecting the according concentration of these substances in HES balanced. Pro-inflammatory cytokines were determined in cell supernatants.

Results

Cytokine mRNA in kidney and liver was increased in CLP animals treated with HES balanced compared to RL, but not after application of HES saline. MCP-1 was 3.5fold (95% CI: 1.3, 5.6) (p<0.01) and TNF-α 2.3fold (95% CI: 1.2, 3.3) (p<0.001) upregulated in the kidney. Corresponding results were seen in liver tissue. TNF-α-stimulated endothelial cells co-exposed to RL expressed 3529±1040pg/mL MCP-1 and 59±23pg/mL CINC-1 protein. These cytokines increased by 2358pg/mL (95% CI: 1511, 3204) (p<0.001) and 29pg/ml (95% CI: 14, 45) (p<0.01) respectively when exposed to HES balanced instead. However, no further upregulation was observed with HES saline. PBS supplemented with acetate increased MCP-1 by 1325pg/mL (95% CI: 741, 1909) (p<0.001) and CINC-1 by 24pg/mL (95% CI: 9, 38) (p<0.01) compared to RL. Malate as well as HES saline did not affect cytokine expression.

Conclusion

We identified HES balanced and specifically its component acetate as pro-inflammatory factor. How important this additional inflammatory burden on kidney and liver function is contributing to the sepsis-associated inflammatory burden in early sepsis needs further evaluation.

Shiga Toxins as Multi-Functional Proteins: Induction of Host Cellular Stress Responses, Role in Pathogenesis and Therapeutic Applications

Shiga toxins (Stxs) produced by Shiga toxin-producing bacteria Shigella dysenteriae serotype 1 and select serotypes of Escherichia coli are primary virulence factors in the pathogenesis of hemorrhagic colitis progressing to potentially fatal systemic complications, such as hemolytic uremic syndrome and central nervous system abnormalities. Current therapeutic options to treat patients infected with toxin-producing bacteria are limited. The structures of Stxs, toxin-receptor binding, intracellular transport and the mode of action of the toxins have been well defined. However, in the last decade, numerous studies have demonstrated that in addition to being potent protein synthesis inhibitors, Stxs are also multifunctional proteins capable of activating multiple cell stress signaling pathways, which may result in apoptosis, autophagy or activation of the innate immune response. Here, we briefly present the current understanding of Stx-activated signaling pathways and provide a concise review of therapeutic applications to target tumors by engineering the toxins.

Could Biomarkers Direct Therapy for the Septic Patient?

Sepsis is a serious medical condition caused by a severe systemic inflammatory response to a bacterial, fungal, or viral infection that most commonly affects neonates and the elderly. Advances in understanding the pathophysiology of sepsis have resulted in guidelines for care that have helped reduce the risk of dying from sepsis for both children and older adults. Still, over the past three decades, a large number of clinical trials have been undertaken to evaluate pharmacological agents for sepsis. Unfortunately, all of these trials have failed, with the use of some agents even shown to be harmful. One key issue in these trials was the heterogeneity of the patient population that participated. What has emerged is the need to target therapeutic interventions to the specific patient's underlying pathophysiological processes, rather than looking for a universal therapy that would be effective in a "typical" septic patient, who does not exist. This review supports the concept that identification of the right biomarkers that can direct therapy and provide timely feedback on its effectiveness will enable critical care physicians to decrease mortality of patients with sepsis and improve the quality of life of survivors.

Neutrophil Extracellular Traps Induce Organ Damage during Experimental and Clinical Sepsis

Organ dysfunction is a major concern in sepsis pathophysiology and contributes to its high mortality rate. Neutrophil extracellular traps (NETs) have been implicated in endothelial damage and take part in the pathogenesis of organ dysfunction in several conditions. NETs also have an important role in counteracting invading microorganisms during infection. The aim of this study was to evaluate systemic NETs formation, their participation in host bacterial clearance and their contribution to organ dysfunction in sepsis. C57Bl/6 mice were subjected to endotoxic shock or a polymicrobial sepsis model induced by cecal ligation and puncture (CLP). The involvement of cf-DNA/NETs in the physiopathology of sepsis was evaluated through NETs degradation by rhDNase. This treatment was also associated with a broad-spectrum antibiotic treatment (ertapenem) in mice after CLP. CLP or endotoxin administration induced a significant increase in the serum concentrations of NETs. The increase in CLP-induced NETs was sustained over a period of 3 to 24 h after surgery in mice and was not inhibited by the antibiotic treatment. Systemic rhDNase treatment reduced serum NETs and increased the bacterial load in non-antibiotic-treated septic mice. rhDNase plus antibiotics attenuated sepsis-induced organ damage and improved the survival rate. The correlation between the presence of NETs in peripheral blood and organ dysfunction was evaluated in 31 septic patients. Higher cf-DNA concentrations were detected in septic patients in comparison with healthy controls, and levels were correlated with sepsis severity and organ dysfunction. In conclusion, cf-DNA/NETs are formed during sepsis and are associated with sepsis severity. In the experimental setting, the degradation of NETs by rhDNase attenuates organ damage only when combined with antibiotics, confirming that NETs take part in sepsis pathogenesis. Altogether, our results suggest that NETs are important for host bacterial control and are relevant actors in the pathogenesis of sepsis.

Trauma in silico: Individual-specific mathematical models and virtual clinical populations

Trauma-induced critical illness is driven by acute inflammation, and elevated systemic interleukin-6 (IL-6) after trauma is a biomarker of adverse outcomes. We constructed a multicompartment, ordinary differential equation model that represents a virtual trauma patient. Individual-specific variants of this model reproduced both systemic inflammation and outcomes of 33 blunt trauma survivors, from which a cohort of 10,000 virtual trauma patients was generated. Model-predicted length of stay in the intensive care unit, degree of multiple organ dysfunction, and IL-6 area under the curve as a function of injury severity were in concordance with the results from a validation cohort of 147 blunt trauma patients. In a subcohort of 98 trauma patients, those with high-IL-6 single-nucleotide polymorphisms (SNPs) exhibited higher plasma IL-6 levels than those with low IL-6 SNPs, matching model predictions. Although IL-6 could drive mortality in individual virtual patients, simulated outcomes in the overall cohort were independent of the propensity to produce IL-6, a prediction verified in the 98-patient subcohort. In silico randomized clinical trials suggested a small survival benefit of IL-6 inhibition, little benefit of IL-1β inhibition, and worse survival after tumor necrosis factor-α inhibition. This study demonstrates the limitations of extrapolating from reductionist mechanisms to outcomes in individuals and populations and demonstrates the use of mechanistic simulation in complex diseases.

Circulating Histones Are Major Mediators of Cardiac Injury in Patients With Sepsis

OBJECTIVE

To investigate the impact of circulating histones on cardiac injury and dysfunction in a murine model and patients with sepsis.

DESIGN

Prospective, observational clinical study with in vivo and ex vivo translational laboratory investigations.

SETTING

General ICU and university research laboratory.

SUBJECTS

Sixty-five septic patients and 27 healthy volunteers. Twelve-week-old male C57BL/6N mice.

INTERVENTIONS

Serial blood samples from 65 patients with sepsis were analyzed, and left ventricular function was assessed by echocardiography. Patients' sera were incubated with cultured cardiomyocytes in the presence or absence of antihistone antibody, and cellular viability was assessed. Murine sepsis was initiated by intraperitoneal Escherichia coli injection (10(8) colony-forming unit/mouse) in 12-week-old male C57BL/6N mice, and the effect of antihistone antibody (10 mg/kg) was studied. Murine blood samples were collected serially, and left ventricular function was assessed by intraventricular catheters and electrocardiography.

MEASUREMENTS AND MAIN RESULTS

Circulating histones and cardiac troponins in human and murine plasma were quantified. In 65 patients with sepsis, circulating histones were significantly elevated compared with healthy controls (n = 27) and linearly correlated with cardiac troponin T levels (rs = 0.650; p < 0.001), noradrenaline doses required to achieve hemodynamic stability (rs = 0.608; p < 0.001), Sequential Organ Failure Assessment scores (p = 0.028), and mortality (p = 0.008). In a subset of 36 septic patients without prior cardiac disease, high histone levels were significantly associated with new-onset left ventricular dysfunction (p = 0.001) and arrhythmias (p = 0.01). Left ventricular dysfunction only predicted adverse outcomes when combined with elevated histones or cardiac troponin levels. Furthermore, patients' sera directly induced histone-specific cardiomyocyte death ex vivo, which was abrogated by antihistone antibodies. In vivo studies on septic mice confirmed the cause-effect relationship between circulating histones and the development of cardiac injury, arrhythmias, and left ventricular dysfunction.

CONCLUSION

Circulating histones are novel and important mediators of septic cardiomyopathy, which can potentially be utilized for prognostic and therapeutic purposes.

Urinary trypsin inhibitor attenuates LPS-induced endothelial barrier dysfunction by upregulation of vascular endothelial-cadherin expression

INTRODUCTION

Urinary trypsin inhibitor (UTI) decreases inflammatory cytokine levels and mortality in experimental animal models of inflammation. Here, we observed the effect of UTI on lipopolysaccharide (LPS)-induced hyperpermeability in human umbilical vein endothelial cells (HUVECs) and explored the role of vascular endothelial-cadherin (VE-cadherin) in its effect.

METHODS

The effect of UTI on endothelial barrier hyperpermeability was detected by an electrical cell-substrate impedance sensing (ECIS) system and a transwell chamber system. The expression of VE-cadherin in HUVECs was examined by real-time PCR and western blot.

RESULTS

We demonstrated that the alleviation of LPS-induced barrier dysfunction could be achieved by pretreatment with 3000 U/mL of UTI. VE-cadherin monoclonal antibody (mAb) could inhibit the protective effects. UTI maintained VE-cadherin expression by increasing protein stability at both the transcriptional and post-transcriptional levels. Meanwhile, VE-cadherin expression on the cell surface increased when the cells were pretreated with UTI. Furthermore, pretreatment with UTI decreased the phosphorylation of VE-cadherin at Tyr658 but not Tyr731.

CONCLUSIONS

Our data show that prophylactic UTI maintains the endothelial barrier function, increases VE-cadherin expression, and inhibits the phosphorylation of VE-cadherin at Tyr658 under inflammatory conditions. It suggests a scientific and potential clinical therapeutic importance of UTI in treatment of inflammatory disorders.

T-5224, a selective inhibitor of c-Fos/activator protein-1, improves survival by inhibiting serum high mobility group box-1 in lethal lipopolysaccharide-induced acute kidney injury model

Background

Sepsis is a potentially fatal syndrome mediated by an early [e.g., tumor necrosis factor-alpha (TNF-α)] and late [high mobility group box-1 (HMGB-1)] proinflammatory cytokine response to infection. Sepsis-induced acute kidney injury (AKI) is associated with a high mortality. C-Fos/activator protein-1 (AP-1) controls the transactivation of proinflammatory cytokines via AP-1 binding in the promoter region. T-5224 is a de novo small molecule inhibitor of c-Fos/AP-1 that controls gene expression of multiple proinflammatory cytokines. We investigated whether T-5224, a selective inhibitor of c-Fos/AP-1, improves survival in lethal lipopolysaccharide (LPS)-induced AKI by inhibiting early (TNF-α) and late (HMGB-1) proinflammatory cytokine response.

Methods

Mice were divided into four groups (control, LPS, LPS + T-5224, and T-5224 only). Control mice were administered polyvinylpyrrolidone (PVP) solution orally, immediately after intraperitoneal (i.p.) saline injection. LPS mice were administered PVP solution orally immediately after i.p. LPS (10 mg/kg) injection. LPS + T-5224 mice were administered T-5224 orally (300 mg/kg) immediately after i.p. LPS injection. T-5224 mice were administered T-5224 orally (300 mg/kg) after i.p. saline injection. Serum concentrations of TNF-α, HMBG-1, and interleukin (IL)-10 were measured by enzyme-linked immunosorbent assay (ELISA). Serum blood urea nitrogen (BUN) and creatinine concentrations were commercially analyzed. Finally, histological examination was performed on the kidney.

Results

Treatment with T-5224 decreased serum TNF-α and HMGB-1 levels and increased survival after LPS injection. Furthermore, T-5224 treatment decreased serum BUN and creatinine concentrations but increased serum IL-10 concentration. LPS-induced pathological changes in kidney were attenuated by T-5224 treatment.

Conclusions

These results suggest that T-5224, a selective inhibitor of c-Fos/AP-1, inhibits expression of early and late proinflammatory cytokines, protecting mice from LPS-induced lethality. T-5224 is a potential approach for decreasing lethality in sepsis-induced AKI.

Persistent lymphopenia is an independent predictor of mortality in critically ill emergency general surgical patients

INTRODUCTION

Lymphopenia has been associated with poor outcome following sepsis, burns and trauma. This study was designed to establish whether lymphocyte count was associated with mortality in emergency general surgery (EGS) patients, and whether persistent lymphopenia was an independent predictor of mortality.

METHODS

A retrospective review of a prospectively compiled database of adult patients requiring ICU admission between 2002 and 2013 was performed. EGS patients with acute intra-abdominal pathology and organ dysfunction were included. Lymphocyte counts obtained from the day of ICU admission through to day 7 were examined. Multivariate logistic regression models were used to determine the relationship between persistent lymphopenia and outcome. The primary outcome measure was in-hospital mortality.

RESULTS

The study included 173 patients, of whom 135 (78 %) had a low lymphocyte count at admission to ICU and 91 % (158/173) developed lymphopenia on at least one occasion. Lymphocyte counts were lower among non-survivors compared with survivors on each day from day 2 (0.62 vs 0.81, p = 0.03) through to day 7 (0.87 vs 1.15, p < 0.01). Patients with a persistently low lymphocyte count during the study period had significantly higher mortality when compared to patients with other lymphocyte patterns (64 vs 29 %, p < 0.01). On multivariate regression analysis, persistent lymphopenia was independently associated with increased in-hospital mortality [odds ratio 3.5 (95 % CI 1.7-7.3), p < 0.01].

CONCLUSION

Lymphopenia is commonly observed in critically ill EGS patients. Patients with persistent lymphopenia are 3.5 times more likely to die and lymphopenia is an independent predictor of increased mortality in this patient group.

Age-related sensitivity to endotoxin-induced liver inflammation: Implication of inflammasome/IL-1β for steatohepatitis

Aging is associated with increased vulnerability to inflammatory challenge. However, the effects of altered inflammatory response on the metabolic status of tissues or organs are not well documented. In this study, we present evidence demonstrating that lipopolysaccharide (LPS)-induced upregulation of the inflammasome/IL-1β pathway is accompanied with an increased inflammatory response and abnormal lipid accumulation in livers of aged rats. To monitor the effects of aging on LPS-induced inflammation, we administered LPS (2 mg kg⁻¹) to young (6-month old) and aged (24-month old) rats and found abnormal lipid metabolism in only aged rats with increased lipid accumulation in the liver. This lipid accumulation in the liver was due to the dysregulation of PPARα and SREBP1c. We also observed severe liver inflammation in aged rats as indicated by increased ALT levels in serum and increased Kupffer cells in the liver. Importantly, among many inflammation-associated factors, the aged rat liver showed chronically increased IL-1β production. Increased levels of IL-1β were caused by the upregulation of caspase-1 activity and inflammasome activation. In vitro studies with HepG2 cells demonstrated that treatment with IL-1β significantly induced lipid accumulation in hepatocytes through the regulation of PPARα and SREBP1c. In summary, we demonstrated that LPS-induced liver inflammation and lipid accumulation were associated with a chronically overactive inflammasome/IL-1β pathway in aged rat livers. Based on the present findings, we propose a mechanism of aging-associated progression of steatohepatitis induced by endotoxin, delineating a pathogenic role of the inflammasome/IL-1β pathway involved in lipid accumulation in the liver.

Contribution of the platelet activating factor signaling pathway to cerebral microcirculatory dysfunction during experimental sepsis by ExoU producing Pseudomonas aeruginosa

Intravital microscopy was used to assess the involvement of ExoU, a Pseudomonas aeruginosa cytotoxin with phospholipase A2 activity, in dysfunction of cerebral microcirculation during experimental pneumosepsis. Cortical vessels from mice intratracheally infected with low density of the ExoU-producing PA103 P. aeruginosa strain exhibited increased leukocyte rolling and adhesion to venule endothelium, decreased capillar density and impaired arteriolar response to vasoactive acetylcholine. These phenomena were mediated by the platelet activating factor receptor (PAFR) pathway because they were reversed in mice treated with a PAFR antagonist prior to infection. Brains from PA103-infected animals exhibited a perivascular inflammatory infiltration that was not detected in animals infected with an exoU deficient mutant or in mice treated with the PAFR antagonist and infected with the wild type bacteria. No effect on brain capillary density was detected in mice infected with the PAO1 P. aeruginosa strain, which do not produce ExoU. Finally, after PA103 infection, mice with a targeted deletion of the PAFR gene exhibited higher brain capillary density and lower leukocyte adhesion to venule endothelium, as well as lower increase of systemic inflammatory cytokines, when compared to wild-type mice. Altogether, our results establish a role for PAFR in mediating ExoU-induced cerebral microvascular failure in a murine model of sepsis.

Dynamic expression of leukocyte innate immune genes in whole blood from horses with lipopolysaccharide-induced acute systemic inflammation

Background

In horses, insights into the innate immune processes in acute systemic inflammation are limited even though these processes may be highly important for future diagnostic and therapeutic advances in high-mortality disease conditions as the systemic inflammatory response syndrome (SIRS) and sepsis. Therefore, the aim of this study was to investigate the expression of 31 selected blood leukocyte immune genes in an equine model of acute systemic inflammation to identify significantly regulated genes and to describe their expression dynamics during a 24-h experimental period. Systemic inflammation was induced in 6 adult horses by the intravenous injection of 1 μg lipopolysaccharide (LPS) per kg btw. Sixteen blood samples were collected for each horse at predetermined intervals and analyzed by reverse transcription quantitative real-time PCR. Post-induction expression levels for each gene were compared with baseline levels.

Results

Systemic inflammation was confirmed by the presence of clinical and hematological changes which were consistent with SIRS. The clinical response to LPS was transient and brief as all horses except one showed unaltered general demeanor after 24 h. Twenty-two leukocyte genes were significantly regulated at at least one time point during the experimental period. By close inspection of the temporal responses the dynamic changes in mRNA abundance revealed a very rapid onset of both pro- and anti-inflammatory mediators and a substantial variation in both expression magnitudes and duration of changes between genes. A majority of the 22 significantly regulated genes peaked within the first 8 h after induction, and an on-going, albeit tightly controlled, regulation was seen after 24 h despite approximate clinical recovery.

Conclusions

This first broad study of gene expressions in blood leukocytes during equine acute LPS-induced systemic inflammation thoroughly characterized a highly regulated and dynamic innate immune response. These results provide new insights into the molecular mechanisms of equine systemic inflammation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-015-0450-5) contains supplementary material, which is available to authorized users.

Pattern and profile of chronic liver disease in acute on chronic liver failure

The etiology of the chronic liver disease (CLD) in patients with acute on chronic liver failure (ACLF) may vary from region to region. The major cause of underlying CLD is viral (hepatitis B and C) in the East, while it is alcohol related in the West and in some parts of the Indian subcontinent. Autoimmune liver disease and Wilson's disease are the major underlying etiologies in the pediatric age group. The patients with CLD without cirrhosis should be included when defining ACLF. Non-alcoholic fatty liver disease related chronic liver insult in patients with known risk factors for progressive disease should be taken as a chronic liver disease in the setting of ACLF, whereas fatty liver with normal aminotransferases in low risk patients should not. The patients with CLD and previous decompensation should be excluded. Diagnosis of chronic liver disease in the setting of ACLF is made by history, physical examination and previously available or recent laboratory, endoscopic or radiological investigations. A liver biopsy through the transjugular route may help in cases where the presence of underlying CLD or its cause is not clear. The need of liver biopsy in ACLF should, however, be individualized. Standardization of liver biopsy assessment is essential for a uniform approach to the diagnosis and treatment of CLD and acute insult. Tools to measure liver stiffness may aid in identifying patients with advanced fibrosis. Studies are needed to validate the performance of these tests in the setting of ACLF.

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.

Reactivation of herpes simplex type 1 in pneumococcal meningitis

BACKGROUND

Acute bacterial meningitis (ABM) and herpes simplex type 1 (HSV-1) encephalitis are two rare but serious infections affecting the central nervous system (CNS). Concurrent bacterial and viral CNS infection has occasionally been reported.

OBJECTIVES

To illustrate the possibility of intrathecal infection with both Streptococcus pneumonia and HSV-1 by presenting a case and to examine whether herpesvirus reactivation is common in ABM.

STUDY DESIGN

We report a case diagnosed with HSV-1 reactivation in the cerebrospinal fluid (CSF) during treatment for pneumococcal ABM. A retrospective analysis of CSF samples from 21 patients with ABM was performed, with analysis of DNA from HSV-1 and four other neurotropic herpesviruses.

RESULTS

All 21CSF samples were negative for HSV-1, HSV-2, varicella zoster-virus, Epstein-Barr virus and human herpesvirus 6 DNA by PCR.

CONCLUSIONS

Although herpesvirus infection does not seem to be a common phenomenon in ABM we suggest that HSV-1 reactivation could be kept in mind if patients with ABM show symptoms or signs compatible with encephalitis.

Xuebijing Ameliorates Sepsis-Induced Lung Injury by Downregulating HMGB1 and RAGE Expressions in Mice

Xuebijing (XBJ) injection, a traditional Chinese medicine, has been reported as a promising approach in the treatment of sepsis in China. However, its actual molecular mechanisms in sepsis-induced lung injury are yet unknown. Therefore, this study aimed to investigate the beneficial effects of XBJ on inflammation and the underlying mechanisms in a model of caecal ligation and puncture-(CLP-) induced lung injury. The mice were divided into CLP group, CLP+XBJ group (XBJ, 4 mL/kg per 12 hours), and sham group. The molecular and histological examinations were performed on the lung, serum, and bronchoalveolar lavage (BAL) fluid samples of mice at the points of 6, 24, and 48 hours after CLP. The results show that XBJ reduces morphological destruction and neutrophil infiltration in the alveolar space and lung wet/dry weight ratio, which improves mortality of CLP-induced lung injury. Meanwhile, XBJ treatment downregulates high mobility group box protein 1 (HMGB1) and the receptor for advanced glycation end products (RAGE) expression, as well as neutrophil counts, production of IL-1β, IL-6, and TNF-α in the BAL fluids. In conclusion, these results indicate that XBJ may reduce the mortality through inhibiting proinflammatory cytokines secretion mediated by HMGB1/RAGE axis.

Use of melatonin as an adjuvant therapy in neonatal sepsis

OBJECTIVE

The objective of this study is to evaluate the therapeutic efficacy of melatonin as an adjuvant therapy in treating neonatal sepsis.

PATIENTS AND METHODS

A prospective clinical trial study was conducted on 50 infants with neonatal sepsis diagnosed on the basis of both clinical and laboratory criteria. Enrolled infants were divided into two groups. Intervention group (n = 25) received melatonin and antibiotics, while the control group (n = 25) was treated with antibiotics only. Melatonin was administered as a single oral dose of 20 mg and antibiotics were administered according to a standard protocol. Both groups were compared using a predefined sepsis score utilizing both clinical and laboratory parameters.

RESULTS

There was no significant difference in sepsis score between both groups before starting melatonin (p-value = 0.99), while there was significant difference in sepsis score between groups after 24 hours, 48 hours and 72 hours of starting melatonin with (p-value = 0.008, 0.006 and 0.002, respectively). There was significant improvement sepsis score in both groups with more improvement of sepsis score in the intervention group.

CONCLUSION

Administration of melatonin as an adjuvant therapy in the treatment of neonatal sepsis is associated with improvement of clinical and laboratory outcomes.

Blockade of the T cell immunoglobulin and mucin domain protein 3 pathway exacerbates sepsis-induced immune deviation and immunosuppression

Sepsis is a life-threatening condition, but the pathophysiological basis and biomarkers for the monitoring of sepsis and as targets for therapy remain to be determined. We have shown previously that T cell immunoglobulin and mucin domain protein 3 (Tim-3), a negative immune regulator, is involved in the physiopathology of sepsis, but the underlying mechanisms remain unclear. In the present study, we showed that Tim-3 signalling modulated the response patterns of both macrophages and T helper cells in sepsis. Blockade of the Tim-3 pathway exacerbated sepsis-induced proinflammatory macrophage responses and lymphocyte apoptosis during the early phase of sepsis, and enhanced the shift to anti-inflammatory responses for both macrophages and T helper cells during the late phase of sepsis. Tim-3 signalling was found to regulate CD80 and CD86 expression on macrophages both in vivo and in vitro. Co-culture of T cells with Tim-3 knock-down macrophages led to a biased T helper type 2 (Th2) response, partially explaining how Tim-3 signalling shapes inflammation patterns in vivo. Further studies on this pathway might shed new light on the pathogenesis of sepsis and suggest new approaches for intervention.

Serum neutrophil gelatinase-associated lipocalin and proinflammatory cytokines in pigs with septic versus non-septic acute kidney injury

BACKGROUND

The aim of this study was to establish a composite pig model with sepsis and ischemic acute kidney injury (AKI) and to investigate the differences in serum neutrophil gelatinase-associated lipocalin (NGAL) and proinflammatory cytokines in septic and non-septic AKI.

METHODS

Seventeen healthy hybridized pigs (weighed 26.97 ± 2.26 kg) were randomly divided into two groups. Group A (n = 12) served as the septic AKI model which received cecal ligation and puncture, resulting in abdominal infection plus clamping of renal artery (CRA). Group B (n = 5) received CRA only. Vital signs and the functions of the main organs were observed. Serum NGAL, TNF-α, and IL-6 were measured at 0, 4, 8, 24, and 48 h after surgical admissions.

RESULTS

Septic AKI model was successfully induced, which manifested as multiple organ dysfunction syndrome, including AKI, liver dysfunction, progressive decline of cardiac function and abnormal pulmonary function. Apparent pathological changes were found in kidney, liver, lung and small intestine of group A. The proinflammatory cytokines in Group A were significantly higher than those in Group B at different time points (P < 0.05). In Group A, serum concentrations of TNF-α reached the peak at 8 h, while IL-6 levels dramatically increased at 24 h. There was a significant difference in serum NGAL between Group A and B at 8 h (P < 0.05).

CONCLUSIONS

Septic AKI animals have higher serum NGAL compared with non-septic AKI animals. Monitoring the activities of TNF-α, NGAL and IL-6 would make great contributions in discovering sepsis and evaluating the severity of sepsis.

Potent antiviral therapy improves survival in acute on chronic liver failure due to hepatitis B virus reactivation

Acute on chronic liver failure (ACLF) is a disease entity with a high mortality rate. The acute event arises from drugs and toxins, viral infections, bacterial sepsis, interventions (both surgical and non-surgical) and vascular events on top of a known or occult chronic liver disease. ACLF secondary to reactivation of chronic hepatitis B virus is a distinct condition; the high mortality of which can be managed in the wake of new potent antiviral therapy. For example, lamivudine and entecavir use has shown definite short-term survival benefits, even though drug resistance is a concern in the former. The renoprotective effects of telbivudine have been shown in a few studies to be useful in the presence of renal dysfunction. Monotherapy with newer agents such as tenofovir and a combination of nucleos(t)ides is promising for improving survival in this special group of liver disease patients. This review describes the current status of potent antiviral therapy in patient with acute on chronic liver failure due to reactivation of chronic hepatitis B, thereby providing an algorithm in management of such patients.

The p38/mitogen-activated protein kinase pathway is implicated in lipopolysaccharide-induced microtubule depolymerization via up-regulation of microtubule-associated protein 4 phosphorylation in human vascular endothelium

BACKGROUND

Microtubules (MTs) play an important role in lipopolysaccharide (LPS)-induced overexpression of inflammatory cytokines and vascular barrier dysfunction; however, the mechanisms behind MT dynamics changes in the vascular endothelium under septic conditions are still not well understood.

METHODS

Human umbilical vein endothelial cells (HUVECs) stimulated with LPS were pretreated with or without the specific p38/mitogen-activated protein kinase (MAPK) inhibitor, SB203580. p38/MAPK cascade-induced signaling events and proteins expression were investigated by Western blotting assay. The interaction between p38/MAPK and microtubule-associated protein 4 (MAP4) was examined by immunoprecipitation. Furthermore, the effects of agonists on LPS-induced MT disruption and alteration of acetylated alpha-tubulin (Acet-tubulin) were analyzed by double-immunofluorescent assay and Western blotting analysis.

RESULTS

In the present study, our results indicated that LPS induced MT depolymerization, but the effects of LPS could be reversed in endothelial cells pretreated with taxol. Furthermore, phosphor-p38 and MAP4 interacted to form a complex after exposure to LPS. LPS-induced MAP4 phosphorylation was greatly suppressed by SB203580, suggesting that activation of p38/MAPK signaling affected MAP4 phosphorylation linked to MT acetylation after stimulation with LPS.

CONCLUSION

The present study demonstrated that the p38/MAPK signaling pathway might disrupt MT dynamics via phosphorylation of MAP4 in vascular endothelial cells challenged by LPS. Our findings provide novel insights into the pathogenic mechanism of MT disassembly and consider new targets for therapeutic intervention under sepsis or septic shock conditions.

Inflammation and the blood microvascular system

Acute and chronic inflammation is associated with changes in microvascular form and function. At rest, endothelial cells maintain a nonthrombogenic, nonreactive surface at the interface between blood and tissue. However, on activation by proinflammatory mediators, the endothelium becomes a major participant in the generation of the inflammatory response. These functions of endothelium are modified by the other cell populations of the microvessel wall, namely pericytes, and smooth muscle cells. This article reviews recent advances in understanding the roles played by microvessels in inflammation.

Proinflammatory role of neutrophil extracellular traps in abdominal sepsis

Excessive neutrophil activation is a major component in septic lung injury. Neutrophil-derived DNA may form extracellular traps in response to bacterial invasions. The aim of the present study was to investigate the potential role of neutrophil extracellular traps (NETs) in septic lung injury. Male C57BL/6 mice were treated with recombinant human (rh)DNAse (5 mg/kg) after cecal ligation and puncture (CLP). Extracellular DNA was stained by Sytox green, and NET formation was quantified by confocal microscopy and cell-free DNA in plasma, peritoneal cavity, and lung. Blood, peritoneal fluid, and lung tissue were harvested for analysis of neutrophil infiltration, NET levels, tissue injury, as well as CXC chemokine and cytokine formation. We observed that CLP caused increased formation of NETs in plasma, peritoneal cavity, and lung. Administration of rhDNAse not only eliminated NET formation in plasma, peritoneal cavity, and bronchoalveolar space but also reduced lung edema and tissue damage 24 h after CLP induction. Moreover, treatment with rhDNAse decreased CLP-induced formation of CXC chemokines, IL-6, and high-mobility group box 1 (HMGB1) in plasma, as well as CXC chemokines and IL-6 in the lung. In vitro, we found that neutrophil-derived NETs had the capacity to stimulate secretion of CXCL2, TNF-α, and HMGB1 from alveolar macrophages. Taken together, our findings show that NETs regulate pulmonary infiltration of neutrophils and tissue injury via formation of proinflammatory compounds in abdominal sepsis. Thus we conclude that NETs exert a proinflammatory role in septic lung injury.

Impact of plasma histones in human sepsis and their contribution to cellular injury and inflammation

Introduction

Circulating histones have been identified as mediators of damage in animal models of sepsis and in patients with trauma-associated lung injury. Despite existing controversies on actual histone concentrations, clinical implications and mechanism of action in various disease conditions, histone levels in human sepsis, association with disease progression and mediated effects on endothelial and immune cells remain unreported. This study aimed to determine histone levels and its clinical implication in septic patients and to elucidate histone-mediated effects ex-vivo.

Methods

Histone levels, endogenous activated protein C (APC) levels and clinical data from two independent cohorts of septic patients were obtained. Histone levels were compared with various control groups including healthy individuals, intensive care unit (ICU) patients without sepsis, ICU patients with multiple organ failure and patients with minor or multiple trauma, all without infection. Endothelial and monocytic cells were stimulated with histones. Cellular integrity and sepsis prototypical cytokines were evaluated. The mechanism of action of histones via Toll-like receptor 4 (TLR4) was evaluated using a function blocking antibody. Histone degradation in plasma was studied by immunoblotting.

Results

Histone H4 levels were significantly elevated in patients with sepsis (cohort I; n = 15 and cohort II; n = 19) versus ICU controls (n = 12), patients with multiple organ failure (n = 12) or minor trauma (n = 7), associated with need for renal replacement therapy and decrease in platelet count during disease progression, and remarkably were significantly associated with increased mortality rates in septic patients (ICU-, 28 day- and 90 day mortality rates). There was an inverse correlation between plasma histones and endogenous APC levels. Histone stimulation induced the release of sepsis prototypic cytokines and decreased cell integrity indicated by a significant increase of lactate dehydrogenase (LDH) and propidium iodide (PI) staining. Blocking of TLR4 decreased cellular cytotoxicity on endothelial cells. The calculated half-life of histones in spiked plasma was 4.6 minutes.

Conclusions

Histone levels in septic patients are significantly increased and might mediate disease aggravation by cellular injury and inflammation via TLR4 signaling, which potentially results in multiple organ failure and fatal outcome.

Receptor-interacting protein kinase 3 deficiency inhibits immune cell infiltration and attenuates organ injury in sepsis

INTRODUCTION

Sepsis is defined as a systemic hyper-inflammatory immune response, with a subsequent immune-suppressive phase, which leads to multiple organ dysfunction and late lethality. Receptor-interacting protein kinase 3 (RIPK3)-dependent necrosis is implicated in driving tumor necrosis factor alpha (TNF-α)- and sepsis-induced mortality in mice. However, it is unknown if RIPK3 deficiency has any impact on immune cell trafficking, which contributes to organ damage in sepsis.

METHODS

To study this, male wild-type (WT) and RIPK3-deficient (Ripk3-/-) mice on C57BL/6 background were subjected to sham operation or cecal ligation and puncture (CLP)-induced sepsis. Blood and tissue samples were collected 20 hours post-CLP for various measurements.

RESULTS

In our severe sepsis model, the mean survival time of Ripk3-/- mice was significantly extended to 68 hours compared to 41 hours for WT mice. Ripk3-/- mice had significantly decreased plasma levels of TNF-α and IL-6 and organ injury markers compared to WT mice post-CLP. In the lungs, Ripk3-/- mice preserved better integrity of microscopic structure with reduced apoptosis, and decreased levels of IL-6, macrophage inflammatory protein (MIP)-2 and keratinocyte-derived chemokine (KC), compared to WT. In the liver, the levels of MIP-1, MIP-2 and KC were also decreased in septic Ripk3-/- mice. Particularly, the total number of neutrophils in the lungs and liver of Ripk3-/- mice decreased by 59.9% and 66.7%, respectively, compared to WT mice post-CLP. In addition, the number of natural killer (NK) and CD8T cells in the liver decreased by 64.8% and 53.4%, respectively, in Ripk3-/- mice compared to WT mice post-sepsis.

CONCLUSIONS

Our data suggest that RIPK3 deficiency modestly protected from CLP-induced severe sepsis and altered the immune cell trafficking in an organ-specific manner attenuating organ injury. Thus, RIPK3 acts as a detrimental factor in contributing to the organ deterioration in sepsis.

Transforming growth factor β-induced protein promotes severe vascular inflammatory responses

RATIONALE

Sepsis is a systemic inflammatory condition resulting from bacterial infections; it has a high mortality rate and limited therapeutic options. Despite extensive research into the mechanisms driving bacterial sepsis, the target molecules controlling vascular leakage are still largely unknown. Transforming growth factor β-induced protein (TGFBIp) is an extracellular matrix protein expressed in several cell types, which is known to interact with integrins.

OBJECTIVES

The aim of this study was to determine the roles of TGFBIp in vascular proinflammatory responses, and the mechanisms of action driving these responses.

METHODS

Circulating levels of TGFBIp were measured in patients admitted to the hospital with sepsis, severe sepsis, and septic shock and in cecal ligation and puncture (CLP)-induced septic mice. Effects of TGFBIp knockout on CLP-induced septic mortality and effects of TGFBIp on multiple vascular proinflammatory responses were determined.

MEASUREMENTS AND MAIN RESULTS

Circulating levels of TGFBIp were significantly elevated compared with healthy controls, and were strongly correlated with disease severity. High blood TGFBIp levels were also observed in CLP-induced septic mice. The absence of the TGFBIp gene in mice attenuated CLP-induced sepsis. TGFBIp enhanced vascular proinflammatory responses including vascular permeability, adhesion and migration of leukocytes, and disruption of adherence junctions through interacting with integrin αvβ5.

CONCLUSIONS

Collectively, our findings demonstrate that the TGFBIp-αvβ5 axis can elicit severe inflammatory responses, suggesting it to be a potential target for development of diagnostics and therapeutics for sepsis.

Nuclear factor of activated T cells regulates neutrophil recruitment, systemic inflammation, and T-cell dysfunction in abdominal sepsis

The signaling mechanisms regulating neutrophil recruitment, systemic inflammation, and T-cell dysfunction in polymicrobial sepsis are not clear. This study explored the potential involvement of the calcium/calcineurin-dependent transcription factor, nuclear factor of activated T cells (NFAT), in abdominal sepsis. Cecal ligation and puncture (CLP) triggered NFAT-dependent transcriptional activity in the lung, spleen, liver, and aorta in NFAT-luciferase reporter mice. Treatment with the NFAT inhibitor A-285222 prior to CLP completely prevented sepsis-induced NFAT activation in all these organs. Inhibition of NFAT activity reduced sepsis-induced formation of CXCL1, CXCL2, and CXCL5 chemokines and edema as well as neutrophil infiltration in the lung. Notably, NFAT inhibition efficiently reduced the CLP-evoked increases in HMBG1, interleukin 6 (IL-6), and CXCL5 levels in plasma. Moreover, administration of A-285222 restored sepsis-induced T-cell dysfunction, as evidenced by markedly decreased apoptosis and restored proliferative capacity of CD4 T cells. Along these lines, treatment with A-285222 restored gamma interferon (IFN-γ) and IL-4 levels in the spleen, which were markedly reduced in septic mice. CLP-induced formation of regulatory T cells (CD4(+) CD25(+) Foxp3(+)) in the spleen was also abolished in A-285222-treated animals. All together, these novel findings suggest that NFAT is a powerful regulator of pathological inflammation and T-cell immune dysfunction in abdominal sepsis. Thus, our data suggest that NFAT signaling might be a useful target to protect against respiratory failure and immunosuppression in patients with sepsis.

Defective autophagy impairs ATF3 activity and worsens lung injury during endotoxemia

Autophagy has emerged as a key regulator of the inflammatory response. To examine the role of autophagy in the development of organ dysfunction during endotoxemia, wild-type and autophagy-deficient (Atg4b-null) mice were challenged with lipopolysaccharide. Animals lacking Atg4b showed increased mortality after endotoxemia. Among the different organs studied, only the lungs showed significant differences between genotypes, with increased damage in mutant animals. Autophagy was activated in lungs from wild-type, LPS-treated mice. Similarly, human bronchial cells show an increased autophagy when exposed to serum from septic patients. We found an increased inflammatory response (increased neutrophilic infiltration, higher levels of Il6, Il12p40, and Cxcl2) in the lungs from knockout mice and identified perinuclear sequestration of the anti-inflammatory transcription factor ATF3 as the putative mechanism responsible for the differences between genotypes. Finally, induction of autophagy by starvation before LPS exposure resulted in a dampened pulmonary response to LPS in wild-type, but not knockout, mice. Similar results were found in human bronchial cells exposed to LPS. Our results demonstrate the central role of autophagy in the regulation of the lung response to endotoxemia and sepsis and its potential modulation by nutrition.

KEY MESSAGES

Endotoxemia and sepsis trigger autophagy in lung tissue. Defective autophagy increases mortality and lung inflammation after endotoxemia. Impairment of autophagy results is perinuclear ATF3 sequestration. Starvation ameliorates lung injury by an autophagy-dependent mechanism.

Alkaline phosphatase: a possible treatment for sepsis-associated acute kidney injury in critically ill patients

Acute kidney injury (AKI) is a common disease in the intensive care unit and accounts for high morbidity and mortality. Sepsis, the predominant cause of AKI in this setting, involves a complex pathogenesis in which renal inflammation and hypoxia are believed to play an important role. A new therapy should be aimed at targeting both these processes, and the enzyme alkaline phosphatase, with its dual mode of action, might be a promising candidate. First, alkaline phosphatase is able to reduce inflammation through dephosphorylation and thereby detoxification of endotoxin (lipopolysaccharide), which is an important mediator of sepsis. Second, adenosine triphosphate, released during cellular stress caused by inflammation and hypoxia, has detrimental effects but can be converted by alkaline phosphatase into adenosine with anti-inflammatory and tissue-protective effects. These postulated beneficial effects of alkaline phosphatase have been confirmed in animal experiments and two phase 2a clinical trials showing that kidney function improved in critically ill patients with sepsis-associated AKI. Because renal inflammation and hypoxia also are observed commonly in AKI induced by other causes, it would be of interest to investigate the therapeutic effect of alkaline phosphatase in these nephropathies as well.

Pathophysiology and management of septic acute kidney injury

Acute kidney injury (AKI) is a commonly encountered complication in critically ill children and portends a worse prognosis. Sepsis-induced AKI (SAKI) is a leading contributor to AKI in children and significantly modifies the risk for less favorable outcome. It has increasingly become clear that SAKI represents a unique and distinct cause of AKI. Studies focused on renal hemodynamics, bioenergetics, and immune-mediated injury have provided further insights into the pathobiology of SAKI; however, many of the nuanced mechanisms remain incompletely understood. Although there have been numerous strategies evaluated for the prevention and management of SAKI, no specific intervention has proven unequivocally efficacious. Currently, the mainstays for managing SAKI focus on alleviating ongoing kidney damage by optimizing systemic and kidney hemodynamic support, avoiding nephrotoxins, and mitigating the anticipated complications of kidney failure. The timely referral for renal support to manage azotemia, metabolic derangements, and fluid accumulation remains critical for this population. The extracorporeal removal of inflammatory mediators has shown some potential benefit in limiting systemic and kidney immune-mediated injury; however, the precise role of these technologies in the management of SAKI has yet to be defined.

Shiga toxins expressed by human pathogenic bacteria induce immune responses in host cells

Shiga toxins are a family of genetically and structurally related toxins that are the primary virulence factors produced by the bacterial pathogens Shigella dysenteriae serotype 1 and certain Escherichia coli strains. The toxins are multifunctional proteins inducing protein biosynthesis inhibition, ribotoxic and ER stress responses, apoptosis, autophagy, and inflammatory cytokine and chemokine production. The regulated induction of inflammatory responses is key to minimizing damage upon injury or pathogen-mediated infections, requiring the concerted activation of multiple signaling pathways to control cytokine/chemokine expression. Activation of host cell signaling cascades is essential for Shiga toxin-mediated proinflammatory responses and the contribution of the toxins to virulence. Many studies have been reported defining the inflammatory response to Shiga toxins in vivo and in vitro, including production and secretion of tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), macrophage inflammatory protein-1α/β (MIP-1α/β), macrophage chemoattractant monocyte chemoattractant protein 1 (MCP-1), interleukin 8 (IL-8), interleukin 6 (IL-6), and Groβ. These cytokines and chemokines may contribute to damage in the colon and development of life threatening conditions such as acute renal failure (hemolytic uremic syndrome) and neurological abnormalities. In this review, we summarize recent findings in Shiga toxin-mediated inflammatory responses by different types of cells in vitro and in animal models. Signaling pathways involved in the inflammatory responses are briefly reviewed.

Utility of sepsis biomarkers and the infection probability score to discriminate sepsis and systemic inflammatory response syndrome in standard care patients

Physicians are regularly faced with severely ill patients at risk of developing infections. In literature, standard care wards are often neglected, although their patients frequently suffer from a systemic inflammatory response syndrome (SIRS) of unknown origin. Fast identification of patients with infections is vital, as they immediately require appropriate therapy. Further, tools with a high negative predictive value (NPV) to exclude infection or bacteremia are important to increase the cost effectiveness of microbiological examinations and to avoid inappropriate antibiotic treatment. In this prospective cohort study, 2,384 patients with suspected infections were screened for suffering from two or more SIRS criteria on standard care wards. The infection probability score (IPS) and sepsis biomarkers with discriminatory power were assessed regarding their capacity to identify infection or bacteremia. In this cohort finally consisting of 298 SIRS-patients, the infection prevalence was 72%. Bacteremia was found in 25% of cases. For the prediction of infection, the IPS yielded 0.51 ROC-AUC (30.1% sensitivity, 64.6% specificity). Among sepsis biomarkers, lipopolysaccharide binding protein (LBP) was the best parameter with 0.63 ROC-AUC (57.5% sensitivity, 67.1% specificity). For the prediction of bacteremia, the IPS performed slightly better with a ROC-AUC of 0.58 (21.3% sensitivity, 65% specificity). Procalcitonin was the best discriminator with 0.78 ROC-AUC, 86.3% sensitivity, 59.6% specificity and 92.9% NPV. Furthermore, bilirubin and LBP (ROC-AUC: 0.65, 0.62) might also be considered as useful parameters. In summary, the IPS and widely used infection parameters, including CRP or WBC, yielded a poor diagnostic performance for the detection of infection or bacteremia. Additional sepsis biomarkers do not aid in discriminating inflammation from infection. For the prediction of bacteremia procalcitonin, and bilirubin were the most promising parameters, which might be used as a rule for when to take blood cultures or using nucleic acid amplification tests for microbiological diagnostics.

Proteomics reveals age-related differences in the host immune response to sepsis

Sepsis is commonly caused by community-acquired pneumonia (CAP) and may develop into severe sepsis, characterized by multiple organ failure. The risk of severe sepsis among CAP patients and subsequent mortality increases sharply after the age of 65. The molecular mechanisms associated with this age-related risk are not fully understood. To better understand factors involved with increased incidence and mortality of severe sepsis in the elderly, we used a nested case-control study of patients enrolled in a multicenter observational cohort of 2320 participants with CAP. We identified a total of 39 CAP patients 50-65 and 70-85 years old who did or did not develop severe sepsis. Plasma samples were obtained on presentation to the emergency department and prior to therapeutic interventions. A semiquantitative plasma proteomics workflow was applied which incorporated tandem immunoaffinity depletion, iTRAQ labeling, strong cation exchange fractionation, and nanoflow liquid chromatography coupled to high-resolution mass spectrometry. In total, 772 proteins were identified, of which 58 proteins exhibit statistically significant differences in expression levels among patients with severe sepsis as a function of age. Differentially expressed proteins are involved in pathways such as acute phase response, coagulation signaling, atherosclerosis signaling, lipid metabolism, and production of nitric oxide and reactive oxygen species. This study provides insight into factors that may explain age-related differences in incidence of severe sepsis in the elderly.

The contribution of group A streptococcal virulence determinants to the pathogenesis of sepsis

Streptococcus pyogenes (group A streptococcus, GAS) is responsible for a wide range of pathologies ranging from mild pharyngitis and impetigo to severe invasive soft tissue infections. Despite the continuing susceptibility of the bacterium to β-lactam antibiotics there has been an unexplained resurgence in the prevalence of invasive GAS infection over the past 30 years. Of particular importance was the emergence of a GAS-associated sepsis syndrome that is analogous to the systemic toxicosis associated with TSST-1 producing strains of Staphylococcus aureus. Despite being recognized for over 20 years, the etiology of GAS associated sepsis and the streptococcal toxic shock syndrome remains poorly understood. Here we review the virulence factors that contribute to the etiology of GAS associated sepsis with a particular focus on coagulation system interactions and the role of the superantigens in the development of streptococcal toxic shock syndrome.