Pathophysiology of sepsis

New Insights into the Immune Molecular Regulation of the Pathogenesis of Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome is an inflammatory disease characterized by dysfunction of pulmonary epithelial and capillary endothelial cells, infiltration of alveolar macrophages and neutrophils, cell apoptosis, necroptosis, NETosis, and fibrosis. Inflammatory responses have key effects on every phase of acute respiratory distress syndrome. The severe inflammatory cascades impaired the regulation of vascular endothelial barrier and vascular permeability. Therefore, understanding the relationship between the molecular regulation of immune cells and the pulmonary microenvironment is critical for disease management. This article reviews the current clinical and basic research on the pathogenesis of acute respiratory distress syndrome, including information on the microenvironment, vascular endothelial barrier and immune mechanisms, to offer a strong foundation for developing therapeutic interventions.

Dual Behavior of Exosomes in Septic Cardiomyopathy

Sepsis is one of the main causes of ICU hospitalization worldwide, with a high mortality rate, and is associated with a large number of comorbidities. One of the main comorbidities associated with sepsis is septic cardiomyopathy. This process occurs mainly due to mechanisms of damage in the cardiovascular system that will lead to changes in cardiovascular physiology, such as decreased Ca²⁺ response, mitochondrial dysfunction and decreased β-adrenergic receptor response. Within this process the exosomes play an important role in the pathophysiology of this disease, in which the exosomal content is related to mechanisms that will trigger its development. After platelet activation through ROS exposition, exosomes containing high concentrations of NADPH are released in heart blood vessels, those exosomes will be internalized in endothelial cells leading to cell death and cardiac dysfunction. On the opposite, exosomes derived from mesenchymal stem cells contain miR-223, that have anti-inflammatory properties, are released in less quantities in septic patients causing an imbalance that leads to cardiac dysfunction.

Early blood stream infection following allogeneic hematopoietic stem cell transplantation is a risk factor for acute grade III-IV GVHD in children and adolescents

BACKGROUND

Graft-versus-host disease (GVHD) remains a major cause of mortality and morbidity in allogeneic hematopoietic stem cell transplantation (HSCT). In adults, early blood stream infection (BSI) and acute GVHD (AGVHD) have been reported to be related. The impact of BSI on risk for AGVHD, however, has not been assessed in pediatric patients.

PROCEDURE

We conducted a retrospective analysis to test the hypothesis that early BSI (before day +30) predisposes allogeneic pediatric transplant patients to severe AGVHD. We analyzed 293 allogeneic HSCT performed at Children's Healthcare of Atlanta between 2005 and 2014 that met eligibility criteria.

RESULTS

The cumulative incidence of acute grade III-IV GVHD at 100 days after HSCT was 17.1%. In multivariate analysis, risk for acute grade III-IV GVHD was associated with HLA-mismatched donor (hazard ratio [HR] = 4.870, P < 0.001), and BSI between day 0 and +30 prior to AGVHD (HR = 3.010, P = 0.001).

CONCLUSIONS

These results indicate that early BSI appears to be a risk factor for acute grade III-IV GVHD. Further research is needed to determine if the link is causal.

Protective Effect of Nicotine on Sepsis-Induced Oxidative Multiorgan Damage: Role of Neutrophils

Introduction

Despite its adverse health consequences, tobacco smoking is associated with lower incidence of several neurodegenerative and inflammatory diseases. The present study is aimed to show the effects of nicotine, major tobacco constituent, on five organs targeted by sepsis.

Methods

Male Wistar albino rats received tap water with (5mg/kg) or without nicotine for 14 days. Under ketamine anesthesia, sepsis (n = 50) was induced by ligation and puncture of the cecum, while sham group (n = 8) had only laparotomy. In other rats, nicotine drink was withdrawn for 5 days before sepsis induction, while in acute nicotine group, rats were injected with nicotine (30mg/kg, i.p.) before sepsis, but had no oral intake. Rats were decapitated 24 hours after surgery to obtain lung, liver, ileum, heart, and kidney tissues to determine malondialdehyde (MDA) and glutathione (GSH) levels and myeloperoxidase (MPO) activities. Data were analyzed by one-way analysis of variance and Tukey multiple comparison tests or Student's t test.

Results

Chronic nicotine administration or its withdrawal reduced lipid peroxidation and MPO activity and prevented GSH depletion with some varying results in different target tissues. Nicotine injection prior to sepsis depressed MPO activity in all tissues and reduced MDA levels except for the lung, while GSH levels were elevated only in the hepatic and ileal tissues. Histologically observed injury was ameliorated by all nicotine treatments at varying degrees.

Conclusions

The findings of the present study indicate that long-term nicotine administration reduces sepsis-induced oxidative damage in several tissues, which appears to involve inhibition of neutrophil activity in the inflamed tissues.

Implications

Nicotine administration or its withdrawal reduced lipid peroxidation and neutrophil content and prevented GSH depletion with some varying results in different target tissues. A single injection prior to sepsis induction depressed MPO activity in all the tissues and reduced all tissue MDA levels except for the lung. When nicotine was withdrawn for 5 days, its inhibitory effect on MPO activity was still present in all the tissues except for the liver. Microscopically an improved inflammatory response was observed in all the tissues of rats that have received different nicotine pretreatment regimens.

Nfia deletion in myeloid cells blocks expansion of myeloid-derived suppressor cells during sepsis

Sepsis-induced immunosuppression increases the risk of chronic infection and reduces survival. Myeloid-derived suppressor cells (MDSCs) expand in the bone marrow and spleen during murine polymicrobial sepsis, contributing to immunosuppression. A better understanding of molecular controls of MDSC production is needed to identify treatment targets. We previously reported that miR-21 and miR-181b couple with transcription factor NFI-A to induce MDSCs during murine sepsis. Here, we expand upon these observations by showing that conditional deletion of the Nfia gene in the myeloid lineage precludes MDSC development. NFI-A-deficient Gr1⁺CD11b⁺ myeloid cells are not immunosuppressive and differentiate normally into macrophages and dendritic cells. In contrast, ectopically expressed NFI-A prevents differentiation of these immature Gr1⁺CD11b⁺ cells, while converting them into MDSCs. In addition, NFI-A-deficient Gr1⁺CD11b⁺ cells decreased, and cells transfected with NFI-A increase expression of miR-21 and miR181b. Our results support a myeloid cell loop in which NFI-A and miR-21 and miR-181b sustain Gr1⁺CD11b⁺ MDSC-dependent immunosuppression during sepsis.

Expression of C/EBPβ in myeloid progenitors during sepsis promotes immunosuppression

Sepsis-induced myeloid-derived suppressor cells (MDSCs) contribute to immunosuppression associated with sepsis. We reported that the CCAAT enhancer-binding protein C/EBPβ activates microRNA (miR)-21 and miR-181b expressions, which induce transcription factor NFI-A to support the generation and expansion of MDSCs in the bone marrow and spleens of septic mice. Here, using a conditional knockout mouse model lacking C/EBPβ in the myeloid lineage, we find that without C/EBPβ, myeloid progenitor cells could not express miR-21 or miR-181b, and ectopic expression of C/EBPβ in the C/EBPβ-deficient myeloid progenitors activated the expression of the two miRNAs. Moreover, C/EBPβ-reconstituted myeloid cells expressed IL-10 and reduced T cell proliferation and function, similar to control MDSCs that express C/EBPβ. Exogenous expression of miR-21 and miR-181b in the C/EBPβ-deficient myeloid progenitors from septic mice produced similar results. Notably, NFI-A-dependent transactivation of NF-kB MDSC generating pathway was reversed in the C/EBPβ-deficient myeloid progenitors from septic mice. Together, these results support that decreasing C/EBPβ expression prevents MDSC generation and decreases immunosuppression in septic mice, providing a target for sepsis treatment.

Concise Review: Mesenchymal Stromal/Stem Cells: A New Treatment for Sepsis and Septic Shock?

Sepsis and septic shock are the leading cause of admission and mortality in non-coronary intensive care units. Currently, however, no specific treatments are available for this syndrome. Due to the failure of conventional treatments in recent years, research is focusing on innovative therapeutic agents, including cell therapy. One particular type of cell, mesenchymal stromal/stem cells (MSCs), has raised hopes for the treatment of sepsis. Indeed, their immunomodulatory properties, antimicrobial activity and capacity of protection against organ failure confer MSCs with a major advantage to treat the immune and inflammatory dysfunctions associated with sepsis and septic shock. After a brief description of the pathophysiology of sepsis and septic shock, the latest advances in the use of MSCs to treat sepsis will be presented. Stem Cells 2017;35:2331-2339.

Controversies in Corticosteroid use for Sepsis

BACKGROUND

Severe sepsis and septic shock are potentially deadly conditions managed in the emergency department (ED). Management centers on source control, fluid resuscitation, broad-spectrum antimicrobials, and vasopressors as needed. The use of corticosteroids is controversial.

OBJECTIVE

To evaluate the evidence behind corticosteroid therapy in patients with septic shock.

DISCUSSION

Septic shock is associated with severe mortality and morbidity. Cytokine release produces a systemic inflammatory state. Vasopressor-resistant septic shock warrants consideration of the disease state and other pathologies such as adrenal insufficiency. Many studies and meta-analyses have been conducted evaluating corticosteroid therapy for this population. High-dose corticosteroid therapy is associated with increased harm, but physiologic-dose corticosteroids may decrease the need for vasopressors. Mortality benefit is controversial, with much of the literature demonstrating no effect. The risk of superinfection is not suggested by the majority of studies. The Surviving Sepsis Campaign advises consideration of corticosteroids in patients with vasopressor and fluid-resistant septic shock. Patients with vasopressor-resistant septic shock with no contraindications to corticosteroids may benefit from hydrocortisone 100 mg intravenously (i.v.) every 8 h or 50 mg i.v. every 6 h. Fludrocortisone is not recommended at this time.

CONCLUSIONS

Septic shock is associated with higher mortality, specifically for patients with vasopressor and fluid-refractory shock. The use of physiologic-dose steroids can reduce vasopressor requirements and improve time of shock resolution. Current literature suggests corticosteroids do not improve mortality, but further studies are required.

The effect of tadalafil therapy on kidney damage caused by sepsis in a polymicrobial septic model induced in rats: a biochemical and histopathological study

Introduction

Sepsis is an inflammatory reaction to bacteria involving the whole body and is a significant cause of mortality and economic costs. The purpose of this research was to determine whether tadalafil exhibits a preventive effect on sepsis in a septic model induced in rats with cecal ligation and puncture (CLP).

Materials and Methods

Rats were randomly separated into groups, 10 rats in each: (i) a sham (control) group, (ii) an untreated sepsis group, (iii) a sepsis group treated with 5mg/kg tadalafil and (iv) a sepsis group treated with 10mg/kg tadalafil. A polymicrobial sepsis model was induced in rats using CLP. Rats were sacrificed after 16h, and blood and kidney tissues were collected for biochemical and histopathological study.

Results

Levels of the inflammatory parameter IL-6 decreased significantly in the sepsis groups receiving tadalafil in comparison with the untreated sepsis group (p<0.05). In terms of histopathology, inflammation scores investigated in kidney tissues decreased significantly in the sepsis groups receiving tadalafil compared to the untreated sepsis group (p<0.05). In addition, levels of creatinine and cystatin C measured in septic rats receiving tadalafil were lower by a clear degree than in septic rats (p<0.05).

Conclusion

In this study, tadalafil exhibited a preventive effect for sepsis-related damage by suppressing inflammation in serum and kidney tissue of septic rats in a polymicrobial sepsis model induced with CLP.

The recognition and management of sepsis and septic shock: a guide for non-intensivists

Sepsis is common, often fatal and requires rapid interventions to improve outcomes. While the optimal management of sepsis in the intensive care setting is the focus of extensive research interest, the mainstay of the recognition and initial management of sepsis will occur outside the intensive care setting. Therefore, it is key that institutions and clinicians remain well informed of the current updates in sepsis management and continue to use them to deliver appropriate and timely interventions to enhance patient survival. This review discusses the latest updates in sepsis care including the new consensus definition of sepsis, the outcome of the proCESS, ProMISe and ARISE trials of early goal directed therapy (EGDT), and the most recent guidelines from the Surviving Sepsis Campaign.

Association of baseline steroid use with long-term rates of infection and sepsis in the REGARDS cohort

BACKGROUND

Prior studies associate steroid use with infection risk but were limited to select populations and short follow-up periods. The association of steroid use with long-term risk of community-acquired infections is unknown. We sought to determine the association of steroid risk with long-term risks of community- acquired infections and sepsis.

METHODS

We used data on 30,239 adults aged ≥ 45 years old from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort. The primary exposure was oral or injectable steroid use, determined from medication inventory obtained at baseline in-home visit. The primary outcome was time to first infection event during 2003-2012, determined through adjudicated review of hospital records. We determined associations between baseline steroid use and first infection hospitalization events using Cox proportional hazards models, adjusting for demographics, health behaviors, chronic medical conditions, and medication adherence. Among the first infection hospitalization events, we also determined the association between baseline steroid use and sepsis.

RESULTS

Steroid use was reported in 2.24% (n = 677) of the study population. There were 2593 incident infection events during the 10-year follow-up period. Infection incidence rates were higher for steroid than non-steroid users (37.99 vs. 13.79 per 1000 person-years). Steroid use was independently associated with increased risk of infection (adjusted HR 2.10, 95% CI: 1.73-2.56). Among first-infection events, steroid use was associated with increased odds of sepsis (adjusted OR 2.11, 95% CI: 1.33-3.36). The associations persisted in propensity matched analyses as well as models stratified by propensity score and medication adherence.

CONCLUSIONS

In this population-based cohort study, baseline steroid use was associated with increased long-term risks of community-acquired infections and sepsis.

Frailty Syndrome and Risk of Sepsis in the REasons for Geographic And Racial Differences in Stroke (REGARDS) Cohort

BACKGROUND:

Frailty is associated with increased morbidity and mortality in older persons. We sought to characterize the associations between the frailty syndrome and long-term risk of sepsis in a large cohort of community-dwelling adults.

METHODS:

We analyzed data on 30 239 community-dwelling adult participants in the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort. We defined frailty as the presence of at least 2 frailty indicators (weakness, exhaustion, and low physical activity). We defined sepsis as hospitalization for a serious infection with ≥2 system inflammatory response syndrome criteria, identified for the period 2003-2012. We determined the associations between frailty and risk of first sepsis and sepsis 30-day case fatality.

RESULTS:

Among REGARDS participants, frailty was present in 6018 (19.9%). Over the 10-year observation period, there were 1529 first-sepsis hospitalizations. Frailty was associated with increased risk of sepsis (adjusted hazard ratio [HR] 1.44; 95% CI: 1.26 to 1.64). The total number of frailty indicators was associated with increased risk of sepsis ( P trend <.001). Among first-sepsis hospitalizations, frailty was associated with increased sepsis 30-day case fatality (adjusted OR 1.62; 95% CI: 1.06 to 2.50).

CONCLUSIONS:

In the REGARDS cohort, frailty was associated with increased long-term risk of sepsis and sepsis 30-day case fatality.

Development of a zebrafish sepsis model for high-throughput drug discovery

Sepsis is a leading cause of death worldwide. Current treatment modalities remain largely supportive. Intervention strategies focused on inhibiting specific mediators of the inflammatory host response have been largely unsuccessful, a consequence of an inadequate understanding of the complexity and heterogeneity of the innate immune response. Moreover, the conventional drug development pipeline is time consuming and expensive and the low success rates associated with cell-based screens underline the need for whole organism screening strategies, especially for complex pathological processes. Here, we established an LPS-induced zebrafish endotoxemia model, which exhibits the major hallmarks of human sepsis including, edema and tissue/organ damage, increased vascular permeability and vascular leakage accompanied by an altered expression of cellular junction proteins, increased cytokine expression, immune cell activation and ROS production, reduced circulation and increased platelet aggregation. We tested the suitability of the model for phenotype-based drug screening using three primary readouts: mortality, vascular leakage, and ROS production. Preliminary screening identified fasudil, a drug known to protect against vascular leakage in murine models, as a lead hit thereby validating the utility of our model for sepsis drug screens. This zebrafish sepsis model has the potential to rapidly analyze sepsis associated pathologies and cellular processes in the whole organism, as well as to screen and validate large numbers of compounds that can modify sepsis pathology in vivo.

Vitamin D and Infectious Diseases: Simple Bystander or Contributing Factor?

Vitamin D (VD) is a fat-soluble steroid essential for life in higher animals. It is technically a pro-hormone present in few food types and produced endogenously in the skin by a photochemical reaction. In recent decades, several studies have suggested that VD contributes to diverse processes extending far beyond mineral homeostasis. The machinery for VD production and its receptor have been reported in multiple tissues, where they have a pivotal role in modulating the immune system. Similarly, vitamin D deficiency (VDD) has been in the spotlight as a major global public healthcare burden. VDD is highly prevalent throughout different regions of the world, including tropical and subtropical countries. Moreover, VDD may affect host immunity leading to an increased incidence and severity of several infectious diseases. In this review, we discuss new insights on VD physiology as well as the relationship between VD status and various infectious diseases such as tuberculosis, respiratory tract infections, human immunodeficiency virus, fungal infections and sepsis. Finally, we critically review the latest evidence on VD monitoring and supplementation in the setting of infectious diseases.

Effect of ulinastatin combined with thymosin alpha1 on sepsis: A systematic review and meta-analysis of Chinese and Indian patients

PURPOSE

To assess the effects of urinary trypsin inhibitor (UTI) ulinastatin combined with thymosin alpha1 (Tα1) on sepsis.

MATERIALS AND METHODS

The meta-analysis included 8 randomized controlled trials (N=1112 patients) on UTI-based therapy for sepsis published before July 10, 2016. Two investigators independently extracted data and assessed the quality of each study. The short-term mortality rate, duration of mechanical ventilator and vasopressor use, length of intensive care unit stay, Acute Physiology and Chronic Health Evaluation (APACHE) II score, and differences in inflammatory cytokines (interleukin [IL]-6, IL-10, and tumor necrosis factor α) were assessed using statistical software.

RESULTS

Treatment of UTI combined with Tα1 (UTI+Tα1) decreased the short-term mortality rate in septic patients by 36%, 35%, and 31% for 28, 60, 90 days, respectively. UTI+Tα1 decreased the duration of mechanical ventilation, APACHE II score, and levels of IL-6 and tumor necrosis factor α. Treatment of UTI+Tα1 did not reduce the duration of vasopressor use and length of intensive care unit stay, or increase IL-10 levels. Because of the high heterogeneity of the included trials, the results should be carefully assessed.

CONCLUSIONS

Treatment of UTI+Tα1 can suppress the production of proinflammatory cytokines, decrease the APACHE II score, shorten the duration of mechanical ventilation, and improve the 28-day survival rate.

The Lysis of Pathogenic Escherichia coli by Bacteriophages Releases Less Endotoxin Than by β-Lactams

BACKGROUND.

Other than numerous experimental data assessing phage therapy efficacy, questions regarding safety of this approach are not sufficiently addressed. In particular, as phages can kill bacterial cells within <10 minutes, the associated endotoxin release (ER) in severe infections caused by gram-negative bacteria could be a matter of concern.

METHODS.

Two therapeutic virulent phages and 4 reference antibiotics were studied in vitro for their ability to kill 2 pathogenic strains of Escherichia coli and generate an ER. The early interaction (first 3 hours) between these actors was assessed over time by studying the instantaneous cell viability, the colony-forming unit count, the concentration of free endotoxin released, and the cell morphology under light microscope.

RESULTS.

While β-lactams have a relatively slow effect, both tested phages, as well as amikacin, were able to rapidly abolish the bacterial growth. Even when considering the fastest phage (cell lysis in 9 minutes), the concentrations of phage-induced ER never reached the highest values, which were recorded with antibiotic treatments. Cumulative concentrations of endotoxin over time in phage-treated conditions were lower than those observed with β-lactams and close to those observed with amikacin. Whereas β-lactams were responsible for strong cell morphology changes (spheroplast with imipenem, filamentous cells with cefoxitin and ceftriaxone), amikacin and phages did not modify cell shape but produced intracellular inclusion bodies.

CONCLUSIONS.

This work provides important and comforting data regarding the safety of phage therapy. Therapeutically relevant phages, with their low endotoxin release profile and fast bactericidal effect, are not inferior to β-lactams.

Continuous hemoadsorption with a cytokine adsorber during sepsis - a review of the literature

Sepsis is a well-recognized healthcare issue worldwide, ultimately resulting in significant mortality, morbidity and resource utilization during and after critical illness. In its most severe form, sepsis causes multi-organ dysfunction that produces a state of critical illness characterized by severe immune dysfunction and catabolism. Sepsis induces the activation of complement factor via 3 pathways and the release of inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin-1beta (IL-1β), resulting in a systemic inflammatory response. The inflammatory cytokines and nitric oxide release induced by sepsis decrease systemic vascular resistance, resulting in profound hypotension. The combination of hypotension and microvascular occlusion results in tissue ischemia and ultimately leads to multiple organ failure. Several clinical and experimental studies have reported that treatment using adsorption of cytokines is beneficial during endotoxemia and sepsis. This review article analyzes the efficacy of CytoSorb® adsorber in reducing the inflammatory response during sepsis. The CytoSorb® adsorber is known to have excellent adsorption rates for inflammatory cytokines such as IL-1β, IL-6, IL-8, IL-10, and TNF-α. Studies have demonstrated that treatment with cytokine adsorbing columns has beneficial effects on the survival rate and inflammatory responses in animal septic models. Additionally, several cases have been reported in which treatment with cytokine adsorbing columns is very effective in hemodynamic stabilization and in preventing organ failure in critically ill patients. Although further investigations and clinical trials are needed, treatment with cytokine adsorbing columns may play an important role in the treatment of sepsis in the near future.

Frontline Science: Myeloid cell-specific deletion of Cebpb decreases sepsis-induced immunosuppression in mice

Sepsis inflammation accelerates myeloid cell generation to compensate for rapid mobilization of the myeloid progenitors from bone marrow. This inflammation-driven myelopoiesis, however, generates myeloid progenitors with immunosuppressive functions that are unable to differentiate into mature, innate immune cells. The myeloid-derived suppressor cells (MDSCs) expand markedly in the later phases of sepsis, suppress both innate and adaptive immunity, and thus, elevate mortality. Using a murine model with myeloid-restricted deletion of the C/EBPβ transcription factor, we show that sepsis-induced generation of MDSCs depends on C/EBPβ. C/EBPβ myeloid cell-deficient mice did not generate MDSCs or develop immunosuppression and survived sepsis. However, septic mice still generated Gr1⁺CD11b⁺ myeloid progenitors at the steady-state levels similar to the control sham mice, suggesting that C/EBPβ is not involved in healthy, steady-state myelopoiesis. C/EBPβ-deficient Gr1⁺CD11b⁺ cells generated fewer monocyte- and granulocyte-like colonies than control mice did, indicating reduced proliferation potential, but differentiated normally in response to growth factors. Adoptive transfer of C/EBPβ-deficient Gr1⁺CD11b⁺ cells from late septic mice exacerbated inflammation in control mice undergoing early sepsis, confirming they were not immunosuppressive. These results show that C/EBPβ directs a switch from proinflammatory to repressor myeloid cells and identifies a novel treatment target.

Sepsis and septic shock: Pathogenesis and treatment perspectives

The majority of bacteremias do not develop to sepsis: bacteria are cleared from the bloodstream. Oxygen released from erythrocytes and humoral immunity kill bacteria in the bloodstream. Sepsis develops if bacteria are resistant to oxidation and proliferate in erythrocytes. Bacteria provoke oxygen release from erythrocytes to arterial blood. Abundant release of oxygen to the plasma triggers a cascade of events that cause: 1. oxygen delivery failure to cells; 2. oxidation of plasma components that impairs humoral regulation and inactivates immune complexes; 3. disseminated intravascular coagulation and multiple organs' failure. Bacterial reservoir inside erythrocytes provides the long-term survival of bacteria and is the cause of ineffectiveness of antibiotics and host immune reactions. Treatment perspectives that include different aspects of sepsis development are discussed.

Cyclosporine A attenuates cardiac dysfunction induced by sepsis via inhibiting calcineurin and activating AMPK signaling

The aim of the present study was to investigate whether cyclosporine A (CSA) improved cardiac dysfunction at an early stage of sepsis. Male Wistar rats were randomly divided into the following three groups: the sham‑operated control group, the cecal ligation puncture (CLP) procedure‑induced sepsis group and the CSA intervention group. Cecal ligation was performed to generate a sepsis model. At different time points (2, 6, 12, 24 and 72 h) following sepsis induction, blood pressure, cardiac function, and non‑esterified free fatty acid (NEFA) levels in the plasma and myocardia were measured, and the expression levels of components associated with the AMP‑activated protein kinase (AMPK)‑acetyl CoA carboxylase (ACC)‑carnitine palmitoyl transferase 1 (CPT1) signaling pathway were compared among the three groups. Sepsis induced a decrease in blood pressure and cardiac function at 24 h following sepsis induction in the CLP group, and CSA treatment ameliorated these pathophysiological alterations. In addition, rats in the CLP group exhibited significant increases in calcineurin activity and NEFA accumulation in the heart when compared with those in the sham group. These effects were attenuated by CSA treatment. Mechanistically, the activity of the AMPK‑ACC‑CPT1 pathway was enhanced by CSA treatment. The present study revealed that CSA treatment increases cardiac function at an early stage of sepsis in rats. This treatment partially suppresses calcineurin activity while activating the AMPK‑TCC‑CPT1 pathway.

Anti-oxidant and anti-inflammatory effects of apigenin in a rat model of sepsis: an immunological, biochemical, and histopathological study

OBJECTIVE

We hypothesize that apigenin may inhibit some cellular process of sepsis-induced spleen injury and simultaneously improve inflammation and oxidative stress. Therefore, the aim of this study was to investigate the potential protective effects of apigenin in a polymicrobial sepsis rat model of by cecal ligation and puncture.

MATERIALS AND METHODS

64 female Wistar albino rats were divided into 8 groups. The pro-inflammatory (tumor necrosis factor-alpha, interleukin-6, and interleukin-1-beta) and anti-inflammatory (tumor growth factor-beta and interleukin-10) cytokine levels were measured by enzyme-linked immunosorbent assay. CD3, CD68, and nuclear factor kappa B (NF-κB) positivity rates were detected by immunohistochemical methods. Oxidative stress parameters were measured by tissue biochemistry.

RESULTS

Sepsis caused a significant increase in TNF-alpha, IL-1-beta, IL-6, and TGF-beta levels whereas it reduced IL-10 level. Additionally, it led to an increase in CD3, CD68, and NF-κB positivity rates as well as oxidative stress parameters levels. However, apigenin inhibited the inflammation process, increased the IL-10 level and normalized the oxidative stress parameters.

DISCUSSION AND CONCLUSION

Pretreatment with apigenin results in a significant reduction in the amount of inflammatory cells. The beneficial effect of apigenin on spleen injury also involved inhibition of NF-κB pathway, suppression of proinflammatory cytokines, and induction of anti-inflammatory cytokine production. Additionally, it led to a decrease in oxidative stress in spleen tissue. Taking everything into account, apigenin may be an alternative therapeutic option for prevention of sepsis-induced organ.

Comparative Assessment of Cytokine Pattern in Early and Late Onset of Neonatal Sepsis

Neonatal sepsis is a significant health issue associated with high mortality. Immune responses associated with neonatal sepsis, such as proinflammatory cytokine production, are believed to play a central role in the pathogenesis of this disease. In the present study, serum levels of the proinflammatory cytokines TNF-α, IL1-β, and IL-6 and the anti-inflammatory cytokines IL-4 and IL-10 were evaluated for 25 subjects with neonatal sepsis. We observed that subjects with late onset of sepsis (LOS), as well as those with early onset of sepsis (EOS), had a substantial increase in serum TNF-α. In contrast to EOS, subjects with LOS demonstrated a significant increase in serum levels IL-6 and IL-10. Additionally, we observed a significant difference in cytokine profiles between acute and postacute cases of neonatal sepsis. For instance, the level of proinflammatory cytokines, such as TNF-α and IL-6, was elevated in the acute phase, whereas the production of anti-inflammatory cytokines, such as IL-10, became substantially upregulated during the postacute phase. Additionally, no correlation was observed between cytokine levels and CRP levels or lymphocyte counts. Thus, in contrast to CRP levels and lymphocyte counts, examination of the cytokine profile can provide valuable information when determining the most effective therapy for treating neonatal sepsis. This information may be useful to physicians when determining if anti-inflammatory or immune stimulatory therapy is warranted.

Anti-inflammatory Properties of Antimicrobial Peptides and Peptidomimetics: LPS and LTA Neutralization

Lipopolysaccharide (LPS) and lipoteichoic acid (LTA) neutralization constitute potential non-antibiotic treatment strategies for sepsis - a systemic infection-induced inflammatory response. Studies on LPS- and LTA-neutralizing compounds are abundant in literature, and a number of peptides and peptidomimetics appear to display promising activity. However, in this ongoing search for potential antisepsis drug leads, it will be preferable that the assays used by different research groups lead to readily comparable data for the most efficient compounds. Here, we propose and describe standardized methods to be used for testing of novel compounds for their LPS- and LTA-neutralizing capacity with a focus on functional suppression of pro-inflammatory responses in cell-based systems. To best mimic the human in vivo conditions, we suggest the use of freshly isolated human leukocytes combined with an appropriate method for the chosen cytokine (e.g., IL-6 or TNF-α). The described protocols comprise isolation, stimulation, and viability test of the human leukocytes.

Deletion of Nlrp3 Augments Survival during Polymicrobial Sepsis by Decreasing Autophagy and Enhancing Phagocytosis

NLRP3 inflammasome is a critical player in innate immunity. Neutrophil recruitment to tissues and effective neutrophil function are critical innate immune mechanisms for bacterial clearance. However, the role of NLRP3 in neutrophil-dependent bacterial clearance in polymicrobial sepsis is unclear. In this study, we evaluated the role of NLRP3 in polymicrobial sepsis induced by cecal ligation and puncture (CLP). Our results showed protection from death in NLRP3-deficient (Nlrp3^-/-) and NLRP3 inhibitor-treated wild-type (C57BL/6) mice. Nlrp3^-/- and NLRP3 inhibitor-treated mice displayed lower bacterial load but no impairment in neutrophil recruitment to peritoneum. However, neutrophil depletion abrogated protection from death in Nlrp3^-/- mice in response to CLP. Intriguingly, following CLP, Nlrp3^-/- peritoneal cells (primarily neutrophils) demonstrate decreased autophagy, augmented phagocytosis, and enhanced scavenger receptor (macrophage receptor with collagenous structure) and mannose-binding leptin expression. These findings enhance our understanding of the critical role of NLRP3 in modulating autophagy and phagocytosis in neutrophils and suggest that therapies should be targeted to modulate autophagy and phagocytosis in neutrophils to control bacterial burden in tissues during CLP-induced polymicrobial sepsis.

Early hemorheological changes in a porcine model of intravenously given E. coli induced fulminant sepsis

The pathophysiology of hemorheological and microcirculatory disturbances in septic process -mostly during the early hours- still not clarified in all the details, yet. In anesthetized pigs living E. coli (ATCC 25922 strain) was administered intravenously with an increasing concentration and the animals were observed for 8 hours. Before the intervention and in every 2 hours arterial (cannulated femoral artery) and venous (cannulated external jugular vein) blood samples were collected for hemorheological laboratory tests: blood and plasma viscosity, ESR, leukocyte anti-sedimentation rate, erythrocyte deformability (together with osmoscan parameters) and erythrocyte aggregation (using light-transmission and laser back-scattering methods) Control animals were stable over the 8-hour anesthesia, while septic animals died by the 6th hours in a fulminant sepsis. Over the experimental period, the tendency of impairment in erythrocyte deformability (together with osmotic gradient ektacytometry parameters) and the controversial decreasing of erythrocyte aggregation values (declining all aggregation index values, elongating t1/2) were well detected in this porcine model during the early hours (4- 6) of fulminant sepsis. The in vitro effect of these bacteria on erythrocytes' micro-rheological parameter was similar: decreasing red blood cell deformability and lowering aggregation. Further studies are needed to clarify the early micro-rheological changes of bacteremia and the developing sepsis.

THE PROTECTIVE ROLE OF CURCUMIN IN ZYMOSAN-INDUCED MULTIPLE ORGAN DYSFUNCTION SYNDROME IN MICE

AIM

Multiple Organ Dysfunction Syndrome (MODS) is characterized as progressive and uncontrolled inflammatory response which involves activation of inflammatory cascades, cytokines release, and endothelial dysfunction, leading to deterioration of several organ functions. Curcumin is a natural polyphenol related to the yellow color of turmeric and has been reported to exert an anti-inflammatory, anti-oxidative, and anti-tumor effect. We conducted the study to investigate the effects of curcumin in non-septic MODS caused by zymosan in mice model.

METHOD

The mice were randomly allocated into five groups (six mice per group): control group (treated with physiological saline, 0.1 mL daily for 3 days before and 1 h after physiological saline treatment), DMSO group (treated with DMSO, 0.1 mL daily for 3 days before and 1 h after physiological saline treatment), Curcumin group (200 mg/kg, suspended in DMSO, in a final volume of 0.1 mL, used for 3 days daily before and 1 h after physiological saline treatment), Zymosan+DMSO group (treated with DMSO, 0.1 mL daily for 3 days before and 1 h after zymosan treatment) and Zymosan+ Curcumin group (treated with curcumin, suspended in DMSO at a dose of 0.1 mL daily for 3 days before and 1 h after zymosan treatment).Mice in groups were sacrificed, and then the blood and tissues were collected to evaluate the severity of acute peritonitis, tissue histopathological changes, NO formation, oxidative stress, PMN infiltration, cytokines production, organ function, and NF-κB activation 18 h after when zymosan or physiological saline was injected. In another set of experiments, the mice were also grouped (20 mice per group) for monitoring the loss of body weight and mortality for 7 days after zymosan or physiological saline administration.

RESULTS

Curcumin induces a significant reduction of the volume exudate and the neutrophil infiltration. It also could exhibit an outstanding protective effect against histopathological injury by decreasing the NO formation, oxidative stress, cytokines production, and infiltration of inflammatory cells. The organ function is also improved by administration of curcumin. Moreover, the activation of NF-κB is attenuated by curcumin in the MODS mice model, suggesting that curcumin attenuated the zymosan-induced MODS via inhibiting the expression of NF-κB possibly. In addition, curcumin-treated mice were shown to alleviate the severity of MODS characterized by a minor systemic toxicity, less body weight loss, and lower mortality caused by zymosan administration.

CONCLUSION

Curcumin attenuates zymosan-induced MODS.

Proteomic profiling identifies N-acetylmuramoyl-l-alanine amidase as a novel biomarker of sepsis

AIM

Sepsis is a critical condition that leads to high mortality and is the most common cause of death in intensive care units. Despite exhaustive efforts by the scientific community, a reliable biomarker for diagnosis, evolution and prognosis of sepsis is still lacking. Results & methodology: Here, using high-throughput proteomics, we describe N-acetylmuramoyl-l-alanine amidase as a novel candidate for differentiating infectious and noninfectious inflammatory syndromes.

DISCUSSION & CONCLUSION

This is the first description of N-acetylmuramoyl-l-alanine amidase as a biomarker that can be used alone or in conjunction with other biomarkers to facilitate the diagnosis of sepsis in the critically ill.

Sustained-Release Buprenorphine Improves Postsurgical Clinical Condition but Does Not Alter Survival or Cytokine Levels in a Murine Model of Polymicrobial Sepsis

Cecal ligation and perforation (CLP) is a common technique for studying sepsis in mice. Because of the invasiveness of the procedure and its effects on clinical condition, many animal care and use committees require the use of analgesics with CLP. However, some analgesics have immunomodulatory effects and thus can hinder the overall research outcomes of a project. Here we sought to determine the effects of buprenorphine hydrochloride (Bup HCl) compared with sustained-release buprenorphine (Bup SR) on clinical condition, plasma concentrations of monocyte chemoattractant protein (MCP) 1 and IL6, and overall mortality in a murine CLP model of sepsis. Male C57/BL6 mice underwent CLP surgery and received Bup HCl or Bup SR as a component of an IACUCapproved analgesic dosing regimen. Mice were observed twice daily for clinical condition scoring by the same blinded investigator for the duration of the study. MCP1 and IL6 levels and mortality did not differ significantly between the 2 groups. Scoring of clinical condition revealed a significant decrease in behaviors associated with perceived pain at 12 and 24 h postoperatively in mice in the Bup SR group compared with the Bup HCl group. Because of the lack of significant effect on MCP1 and IL6 levels and mortality and the superior analgesic effects of Bup SR, we recommend the use of Bup SR for analgesia during the murine CLP model of sepsis.

Practical Considerations in Sepsis Resuscitation

BACKGROUND

Sepsis is a common condition managed in the emergency department, and the majority of patients respond to resuscitation measures, including antibiotics and i.v. fluids. However, a proportion of patients will fail to respond to standard treatment.

OBJECTIVE

This review elucidates practical considerations for management of sepsis in patients who fail to respond to standard treatment.

DISCUSSION

Early goal-directed therapy revolutionized sepsis management. However, there is a paucity of literature that provides a well-defined treatment algorithm for patients who fail to improve with therapy. Refractory shock can be defined as continued patient hemodynamic instability (mean arterial pressure, ≤ 65 mm Hg, lactate ≥ 4 mmol/L, altered mental status) after adequate fluid loading (at least 30 mL/kg i.v.), the use of two vasopressors (with one as norepinephrine), and provision of antibiotics. When a lack of improvement is evident in the early stages of resuscitation, systematically considering source control, appropriate volume resuscitation, adequate antimicrobial coverage, vasopressor selection, presence of metabolic pathology, and complications of resuscitation, such as abdominal compartment syndrome and respiratory failure, allow emergency physicians to address the entire clinical scenario.

CONCLUSIONS

The care of sepsis has experienced many changes in recent years. Care of the patient with sepsis who is not responding appropriately to initial resuscitation is troublesome for emergency physicians. This review provides practical considerations for resuscitation of the patient with septic shock. When a septic patient is refractory to standard therapy, systematically evaluating the patient and clinical course may lead to improved outcomes.

Sepsis Bundles and Compliance With Clinical Guidelines

Realizing the vast medical benefits of validated protocols, recommendations and practice guidelines requires acceptance and implementation by frontline care providers. Knowledge translation is the science of accelerating the transfer of knowledge to practice by understanding and creatively addressing the barriers that prevent adoption of new professional standards. In an attempt to improve patient care and reduce mortality, the Surviving Sepsis Campaign and The Institute for Healthcare Improvement created the resuscitation and management bundles for patients with severe sepsis and septic shock. These bundles have been accepted as best practice by many clinicians since multiple clinical trials have produced similar positive results when they were implemented. However, transferring these research outcomes-based guidelines to the clinical practice arena has been associated with poor compliance due to important barriers to implementation. Delays in the adoption of sepsis bundles are not surprising since the time from validation to implementation of a new clinical practice is typically 17 years. Using sepsis bundles as a model, this article explores why guidelines are important, examines physician adherence to protocols, and reviews the literature on strategies to improve clinical compliance and enhance knowledge translation.

The association of unipolar depression with thirty-day mortality after hospitalization for infection: A population-based cohort study in Denmark

OBJECTIVE

While depression is associated with higher risk of death due to chronic medical conditions, it is unknown if depression increases mortality following serious infections. We sought to determine if pre-existing unipolar depression is associated with increased mortality within 30days after hospitalization for a serious infection.

METHODS

We conducted a population-based cohort study of all adults hospitalized for an infection in Denmark between 2005 and 2013. Pre-existing unipolar depression was ascertained via psychiatrist diagnoses or at least two antidepressant prescription redemptions within a six month period. Our primary outcome was all-cause mortality within 30days after infection-related hospitalization. We also studied death due to infection within 30days after admission.

RESULTS

We identified 589,688 individuals who had a total of 703,158 hospitalizations for infections. After adjusting for demographics, infectious diagnosis and time since infection, socioeconomic factors and comorbidities, pre-existing unipolar depression was associated with slightly increased risk of all-cause mortality within 30days after infection-related hospitalization (Mortality Rate Ratio [MRR]: 1.07, 95% Confidence Interval [95% CI]: 1.05, 1.09). The association was strongest among persons who initiated antidepressant treatment within one year before the infection (MRR: 1.30, 95% CI: 1.25, 1.35). Pre-existing unipolar depression was associated with increased risk of death due to sepsis (MRR: 1.30, 95% CI: 1.17, 1.44), pneumonia (MRR: 1.23, 95% CI: 1.16, 1.29) and urinary tract infection (MRR: 1.25, 95% CI: 1.08, 1.44) after adjusting for demographics, infectious diagnosis at admission and time since infection.

CONCLUSIONS

Pre-existing unipolar depression is associated with slightly increased mortality following hospitalization for an infection.

Milk fat globule-epidermal growth factor-factor VIII-derived peptide MSP68 is a cytoskeletal immunomodulator of neutrophils that inhibits Rac1

BACKGROUND

Prolonged neutrophil infiltration leads to exaggerated inflammation and tissue damage during sepsis. Neutrophil migration requires rearrangement of their cytoskeleton. Milk fat globule-epidermal growth factor-factor VIII-derived short peptide 68 (MSP68) has recently been shown to be beneficial in sepsis-induced tissue injury and mortality. We hypothesize that MSP68 inhibits neutrophil migration by modulating small GTPase Rac1-dependent cytoskeletal rearrangements.

METHODS

Bone marrow-derived neutrophils (BMDNs) or whole lung digest isolated neutrophils were isolated from 8 to 10 wk old C57BL/6 mice by Percoll density gradient centrifugation. The purity of BMDN was verified by flow cytometry with CD11b/Gr-1 staining. Neutrophils were stimulated with N-formylmethionine-leucine-phenylalanine (f-MLP) (10 nM) in the presence or absence of MSP68 at 10 nM or cecal ligation and puncture (CLP) was used to induce sepsis, and MSP68 was administered at 1 mg/kg intravenously. Cytoskeletal organization was assessed by phalloidin staining, followed by analysis using fluorescence microscopy. Activity of the Rac1 GTPase in f-MLP or CLP-activated BMDN in the presence or absence of MSP68 was assessed by GTPase enzyme-linked immunosorbent assay. Mitogen-activated protein (MAP) kinase activity was determined by western blot densitometry.

RESULTS

BMDN treatment with f-MLP increased cytoskeletal remodeling as revealed by the localization of filamentous actin to the periphery of the neutrophil. By contrast, cells pretreated with MSP68 had considerably reduced filamentous actin polymerization. Cytoskeletal spreading is associated with the activation of the small GTPase Rac1. We found BMDN-treated with f-MLP or that were exposed to sepsis by CLP had increased Rac1 signaling, whereas the cells pretreated with MSP68 had significantly reduced Rac1 activation (P < 0.05). MAP kinases related to cell migration including pp38 and pERK were upregulated by treatment with f-MLP. Upregulation of these MAP kinases was also significantly reduced after pretreatment with MSP68 (P < 0.05).

CONCLUSIONS

MSP68 downregulates actin cytoskeleton-dependent, Rac1-MAP kinase-mediated neutrophil motility. Thus, MSP68 is a novel therapeutic candidate for regulating inflammation and tissue damage caused by excessive neutrophil migration in sepsis.

The Use of Exosomes as Biomarkers for Evaluating and Monitoring Critically Ill Polytrauma Patients with Sepsis

Regarding genetic biomarkers for early assessment and monitoring the clinical course in polytrauma patients with sepsis, in recent years a remarkable evolution has been highlighted. One of the main representatives is the exosome miRNAs. In this paper, we would like to present in more details the various methods of using exosome miRNAs as a biomarker for monitoring polytrauma patients with sepsis, as well as establishing a belated outcome by aggregating the entire clinical aspects. The use of exosome miRNAs for late evaluating and monitoring the clinical evolution of polytrauma patients can bring significant improvements in current clinical practice through the optimization and modulation of intensive care according to the needs of each patient individually.

The effects of early high-volume hemofiltration on prolonged cardiac arrest in rats with reperfusion by cardiopulmonary bypass: a randomized controlled animal study

Background

It is not yet clear whether hemofiltration can reduce blood cytokine levels sufficiently to benefit patients who suffer prolonged cardiac arrest (CA) treated with cardiopulmonary bypass (CPB). We sought to assess effects of high-volume and standard volume continuous veno-venous hemofiltration (CVVH) on blood cytokine levels and survival in a rat model of prolonged CA treated with CPB.

Methods

Sprague-Dawley male rats were subjected to 12 min of asphyxia to induce CA. CPB was initiated for resuscitation of animals and maintained for 30 min. Twenty-four rats were randomly assigned into three groups: without CVVH treatment (sham); standard volume CVVH at a filtration rate of 35–45 mL/kg/h; and high-volume hemofiltration (HVHF, 105–135 mL/kg/h). Hemofiltration was started simultaneously with CPB and maintained for 6 h. Plasma TNFα and IL-6 levels were measured at baseline, 0.5, 1, 2, 3, and 6 h after reperfusion. Survival time, neurological deficit score, and hemodynamic status were assessed.

Results

All animals survived over 6 h and died within 24 h. There were no significant differences in survival time (log-rank test, sham vs. CVVH; p = 0.49, sham vs. HVHF; p = 0.33) or neurological deficit scores (ANOVA, p = 0.14) between the groups. There were no significant differences in blood cytokine levels between the groups. Mean blood pressure in sham group animals increased to 1.5-fold higher than baseline levels at 30 min. HVHF significantly reduced blood pressure to 0.7-fold of sham group (p < 0.01).

Conclusions

There was no improvement in mortality, neurological dysfunction, TNFα, or IL-6 levels in rats after prolonged CA with CPB on either hemofiltration group when compared to the sham group.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-016-0101-6) contains supplementary material, which is available to authorized users.

Effect of parenteral glutamine supplementation combined with enteral nutrition on Hsp90 expression and lymphoid organ apoptosis in severely burned rats

OBJECTIVE

The aim of this study is to investigate the effects of parenteral glutamine(GLN) supplementation combined with enteral nutrition (EN) on heat shock protein 90(Hsp90) expression, apoptosis of lymphoid organs and circulating lymphocytes, immunological function and survival in severely burned rats.

METHODS

Male SD rats were randomly assigned into 4 groups: a sham burn+EN+GLN-free amino acid (AA) group (n=10), a sham burn+EN+GLN group (n=10), a burn+EN+AA group (n=10), and a burn +EN +GLN group (n=10). Two hours after a 30% total body surface area (TBSA), full-thickness scald burn injury on the back was made, the burned rats in two experimental groups (the burn+EN+AA group and the burn+EN +GLN group) were fed with a conventional enteral nutrition solution by oral gavage for 7 days. Simultaneously, the rats in the burn+EN+GLN group were given 0.35g GLN/kg body weight/day once via a tail vein injection for 7 days, whereas those in the burn+EN+AA group were administered isocaloric/isonitrogenous GLN-free amino acid solution (Tyrosine) for comparison. The rats in two sham burn control groups (the sham burn+EN+AA group and the sham burn+EN +GLN group) were treated in the same procedure as above, except for burn injury. All rats in each of the four groups were given 175kcal/kg body wt/day. There was isonitrogenous, isovolumic and isocaloric intake among four groups. At the end of the 7th day after nutritional programme were finished, all rats were anesthetized and samples were collected for further analysis. Serum immunoglobulin quantification was conducted by ELISA. Circulating lymphocyte numbers were counted by Coulter LH-750 Analyzer. The percentages and apoptotic ratio of CD4 and CD8T lymphocytes in circulation were determined by flow cytometry (FCM). The neutrophil phagocytosis index (NPI) was examined. The GLN concentrations in plasma, thymus, spleen and skeletal muscle were measured by high performance liquid chromatography (HPLC). The organ index evaluation and TUNEL analysis of thymus and spleen were carried out. The expression of Hsp90 in thymus and spleen was analyzed by western blotting. Moreover, the survival in burned rats was observed.

RESULTS

The results revealed that parenteral GLN supplementation combined with EN significantly increased the GLN concentrations of plasma and tissues, the serum immunoglobulin content, the circulating lymphocyte number, the CD4/CD8 ratio, the indexes of thymus and spleen, NPI and survival as compared with the burn+EN+AA group (p<0.05). The expression of Hsp90 in thymus and spleen in the burn+EN+GLN group was significantly up-regulated as compared with the burn+EN+AA group (p<0.05). The apoptosis in circulating CD4 and CD8 lymphocytes, thymus and spleen in the burn+EN+GLN group was significantly decreased as compared with the burn+EN+AA group (p<0.05).

CONCLUSION

The results of this study show that parenteral GLN supplementation combined with EN may increase the GLN concentrations of plasma and tissues, up-regulate the expression of Hsp90, attenuate apoptosis in lymphoid organ and circulating lymphocyte, enhance the immunological function and improve survival in severely burned rats. Clinically, therapeutic efforts at the modulation of the immune dysfunction may contribute to a favorable outcome in severely burned patients.

Cystathionine-Gamma-Lyase Gene Deletion Protects Mice against Inflammation and Liver Sieve Injury following Polymicrobial Sepsis

Background

Hydrogen sulfide (H₂S), produced by the activity of cystathionine-gamma-lyase (CSE), is a key mediator of inflammation in sepsis. The liver sinusoidal endothelial cells (LSECs) are important target and mediator of sepsis. The aim of this study was to investigate the role of CSE-derived H₂S on inflammation and LSECs fenestrae in caecal-ligation and puncture (CLP)-induced sepsis using CSE KO mice.

Methods

Sepsis was induced by CLP, and mice (C57BL/6J, male) were sacrificed after 8 hours. Liver, lung, and blood were collected and processed to measure CSE expression, H₂S synthesis, MPO activity, NF-κB p65, ERK1/2, and cytokines/chemokines levels. Diameter, frequency, porosity and gap area of the liver sieve were calculated from scanning electron micrographs of the LSECs.

Results

An increased CSE expression and H₂S synthesizing activity in the liver and lung of wild-type mice following CLP-induced sepsis. This was associated with an increased liver and lung MPO activity, and increased liver and lung and plasma levels of the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β, and the chemokines MCP-1 and MIP-2α. Conversely, CSE KO mice had less liver and lung injury and reduced inflammation following CLP-induced sepsis as evidenced by decreased levels of H₂S synthesizing activity, MPO activity, and pro-inflammatory cytokines/chemokines production. Extracellular-regulated kinase (ERK1/2) and nuclear factor-κB p65 (NF-κB) became significantly activated after the CLP in WT mice but not in CSE KO mice. In addition, CLP-induced damage to the LSECs, as indicated by increased defenestration and gaps formation in the LSECs compared to WT sham control. CSE KO mice showed decreased defenestration and gaps formation following sepsis.

Conclusions

Mice with CSE (an H₂S synthesising enzyme) gene deletion are less susceptible to CLP-induced sepsis and associated inflammatory response through ERK1/2-NF-κB p65 pathway as evidenced by reduced inflammation, tissue damage, and LSECs defenestration and gaps formation.

Effect of high-dose Ascorbic acid on vasopressor's requirement in septic shock

Objective:

Effects of ascorbic acid on hemodynamic parameters of septic shock were evaluated in nonsurgical critically ill patients in limited previous studies. In this study, the effect of high-dose ascorbic acid on vasopressor drug requirement was evaluated in surgical critically ill patients with septic shock.

Methods:

Patients with septic shock who required a vasopressor drug to maintain mean arterial pressure >65 mmHg were assigned to receive either 25 mg/kg intravenous ascorbic acid every 6 h or matching placebo for 72 h. Vasopressor dose and duration were considered as the primary outcomes. Duration of Intensive Care Unit (ICU) stay and 28-day mortality has been defined as secondary outcomes.

Findings:

During the study period, 28 patients (14 in each group) completed the trial. Mean dose of norepinephrine during the study period (7.44 ± 3.65 vs. 13.79 ± 6.48 mcg/min, P = 0.004) and duration of norepinephrine administration (49.64 ± 25.67 vs. 71.57 ± 1.60 h, P = 0.007) were significantly lower in the ascorbic acid than the placebo group. No statistically significant difference was detected between the groups regarding the length of ICU stay. However, 28-day mortality was significantly lower in the ascorbic acid than the placebo group (14.28% vs. 64.28%, respectively; P = 0.009).

Conclusion:

High-dose ascorbic acid may be considered as an effective and safe adjuvant therapy in surgical critically ill patients with septic shock. The most effective dose of ascorbic acid and the best time for its administration should be determined in future studies.

Natural History of Aerosol Exposure with Marburg Virus in Rhesus Macaques

Marburg virus causes severe and often lethal viral disease in humans, and there are currently no Food and Drug Administration (FDA) approved medical countermeasures. The sporadic occurrence of Marburg outbreaks does not allow for evaluation of countermeasures in humans, so therapeutic and vaccine candidates can only be approved through the FDA animal rule—a mechanism requiring well-characterized animal models in which efficacy would be evaluated. Here, we describe a natural history study where rhesus macaques were surgically implanted with telemetry devices and central venous catheters prior to aerosol exposure with Marburg-Angola virus, enabling continuous physiologic monitoring and blood sampling without anesthesia. After a three to four day incubation period, all animals developed fever, viremia, and lymphopenia before developing tachycardia, tachypnea, elevated liver enzymes, decreased liver function, azotemia, elevated D-dimer levels and elevated pro-inflammatory cytokines suggesting a systemic inflammatory response with organ failure. The final, terminal period began with the onset of sustained hypotension, dehydration progressed with signs of major organ hypoperfusion (hyperlactatemia, acute kidney injury, hypothermia), and ended with euthanasia or death. The most significant pathologic findings were marked infection of the respiratory lymphoid tissue with destruction of the tracheobronchial and mediastinal lymph nodes, and severe diffuse infection in the liver, and splenitis.

Cystathionine-γ-lyase gene silencing with siRNA in monocytes/ macrophages attenuates inflammation in cecal ligation and puncture-induced sepsis in the mouse

Hydrogen sulphide is an endogenous inflammatory mediator produced by cystathionine-γ-lyase (CSE) in macrophages. To determine the role of H2S and macrophages in sepsis, we used small interference RNA (siRNA) to target the CSE gene and investigated its effect in a mouse model of sepsis. Cecal ligation puncture (CLP)-induced sepsis is characterized by increased levels of myeloperoxidase (MPO) activity, morphological changes in liver and pro-inflammatory cytokines and chemokines in the liver and lung. SiRNA treatment attenuated inflammation in the liver and lungs of mice following CLP-induced sepsis. Liver MPO activity increased in CLP-induced sepsis and treatment with siRNA significantly reduced this. Similarly, lung MPO activity increased following induction of sepsis with CLP while siRNA treatment significantly reduced MPO activity. Liver and lung cytokine and chemokine levels in CLP-induced sepsis reduced following treatment with siRNA. These findings show a crucial pro-inflammatory role for H2S synthesized by CSE in macrophages in sepsis and suggest CSE gene silencing with siRNA as a potential therapeutic approach for this condition.

Surviving sepsis in the critical care environment

The management of sepsis and septic shock in the intensive care environment is a complex task requiring the cooperation of a multidisciplinary team. The Surviving Sepsis Campaign provides systematic guidelines for the recognition, early intervention, and supportive management of sepsis. Critical care nurses are instrumental in ensuring that these guidelines and other sources of evidence-based practice are used for patients with severe sepsis or septic shock. This article discusses the pathophysiologic processes in severe sepsis and septic shock and discusses the appropriate interventions as recommended by the Surviving Sepsis Campaign. Recommended early treatments are reviewed along with interventions related to hemodynamics, perfusion, and supportive care in the critical care environment.

Survival benefits of remote ischemic conditioning in sepsis

BACKGROUND

Sepsis remains the leading cause of death in the surgical intensive care unit. Prior studies have demonstrated a survival benefit of remote ischemic conditioning (RIC) in many disease states. The aim of this study was to determine the effects of RIC on survival in sepsis in an animal model and to assess alterations in inflammatory biochemical profiles. We hypothesized that RIC alters inflammatory biochemical profiles resulting in decreased mortality in a septic mouse model.

MATERIALS AND METHODS

Eight to 12 week C57BL/6 mice received intra-peritoneal injection of 12.5-mg/kg lipopolysaccharide (LPS). Septic animals in the experimental group underwent RIC at 0, 2, and 6 h after LPS by surgical exploration and alternate clamping of the femoral artery. Six 4-min cycles of ischemia-reperfusion were performed. Primary outcome was survival at 5-d after LPS injection. Secondary outcome was to assess the following serum cytokine levels: interferon-γ (IFN-γ), interleukin (IL)-10, IL-1β, and tumor necrosis factoralpha (TNFα) at the baseline before LPS injection, 0 hour after LPS injection, and at 2, 4, 24 hours after induction of sepsis (RIC was performed at 2 h after LPS injection). Kaplan-Meier survival analysis and log-rank test were used. ANOVA test was used to compare cytokine measurements.

RESULTS

We performed experiments on 44 mice: 14 sham and 30 RIC mice (10 at each time point). Overall survival was higher in the experimental group compared to the sham group (57% versus 21%; P = 0.02), with the highest survival rate observed in the 2-hour post-RIC group (70%). On Kaplan-Meier analysis, 2-h post-RIC group had increased survival at 5 days after LPS (P = 0.04) with hazard ratio of 0.3 (95% confidence interval = 0.09-0.98). In the RIC group, serum concentrations of IFN-γ, IL-10, IL-1β, and TNFα peaked at 2 h after LPS and then decreased significantly over 24 hours (P < 0.0001) compared to the baseline.

CONCLUSIONS

RIC improves survival in sepsis and has the potential for implementation in the clinical practice. Early implementation of RIC may play an immune-modulatory role in sepsis. Further studies are necessary to refine understanding of the observed survival benefits and its implications in sepsis management.

IL-15 Superagonist Expands mCD8+ T, NK and NKT Cells after Burn Injury but Fails to Improve Outcome during Burn Wound Infection

Background

Severely burned patients are highly susceptible to opportunistic infections and sepsis, owing to the loss of the protective skin barrier and immunological dysfunction. Interleukin-15 (IL-15) belongs to the IL-2 family of common gamma chain cytokines and stimulates the proliferation and activation of T (specifically memory CD8), NK and NKT cells. It has been shown to preserve T cell function and improve survival during cecal ligation and puncture (CLP)-induced sepsis in mice. However, the therapeutic efficacy of IL-15 or IL-15 superagonist (SA) during infection after burn injury has not been evaluated. Moreover, very few, if any, studies have examined, in detail, the effect of burn injury and infection on the adaptive immune system. Thus, we examined the effect of burn and sepsis on adaptive immune cell populations and the effect of IL-15 SA treatment on the host response to infection.

Methods

Mice were subjected to a 35% total body surface area burn, followed by wound infection with Pseudomonas aeruginosa. In some experiments, IL-15 SA was administered after burn injury, but before infection. Leukocytes in spleen, liver and peritoneal cavity were characterized using flow cytometry. Bacterial clearance, organ injury and survival were also assessed.

Results

Burn wound infection led to a significant decline in total white blood cell and lymphocyte counts and induced organ injury and sepsis. Burn injury caused decline in CD4⁺ and CD8⁺ T cells in the spleen, which was worsened by infection. IL-15 treatment inhibited this decline and significantly increased cell numbers and activation, as determined by CD69 expression, of CD4⁺, CD8⁺, B, NK and NKT cells in the spleen and liver after burn injury. However, IL-15 SA treatment failed to prevent burn wound sepsis-induced loss of CD4⁺, CD8⁺, B, NK and NKT cells and failed to improve bacterial clearance and survival.

Conclusion

Cutaneous burn injury and infection cause significant adaptive immune dysfunction. IL-15 SA does not augment host resistance to burn wound sepsis in mice despite inducing proliferation and activation of lymphocyte subsets.