Treatment options for severe sepsis and septic shock

Mediatory roles of leukotriene B4 receptors in LPS-induced endotoxic shock

Sepsis, a systemic inflammatory response syndrome caused by infection, is the most common disease in patients treated in intensive care units. Endotoxic shock, the most critical form of sepsis, is caused by gram-negative bacterial infection. However, the detailed mechanism of endotoxic shock remains unclear. In the present study, we observed that the production of leukotriene B₄ (LTB₄) and 12(S)-hydroxyeicosatetraenoic acid (HETE), inflammatory lipid mediators acting on LTB₄ receptors (BLT1 and BLT2), was significantly upregulated in peritoneal lavage fluid (PF) and serum from an LPS-induced endotoxic shock mouse model. Furthermore, BLT1/2-dependent signaling pathways mediated the expression of IL-17, IL-6, and IL-1β, key cytokines for the development of endotoxic shock, via NF-κB activation in the LPS-induced endotoxic shock mouse model. Additionally, inhibition of BLT1/2 significantly attenuated inflammation and tissue damage associated with endotoxic shock and enhanced the survival rate of mice with this inflammatory complication. Together, these results suggest that LTB₄ receptors play critical mediatory roles in the development of endotoxic shock. Our findings point to LTB₄ receptors as potential therapeutic targets for the treatment of endotoxic shock.

Whey Acidic Protein/Four-Disulfide Core Domain 21 Regulate Sepsis Pathogenesis in a Mouse Model and a Macrophage Cell Line via the Stat3/Toll-Like Receptor 4 (TLR4) Signaling Pathway

Background

Whey acidic protein/four-disulfide core domain 21 (Wfdc21), also known as Lnc-DC, it has been reported to be correlated with immune response. However, the role of Wfdc21 in the pathogenesis of sepsis is still unknown. In the present study, we aimed to investigate the role of Wfdc21 in the pathogenesis of sepsis.

Material/Methods

The cecal ligation and puncture (CLP)-induced sepsis model was established in Balb/c mice. Animals were euthanized 4, 8, 16, or 24 h after CLP. The glycogen distribution in the kidney and liver was checked by Periodic acid-Schiff (PAS) staining. Changes in the serum interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations were monitored with ELISA, and Wdfc21 expression was determined by qPCR. Mouse macrophage-like RAW264.7 cells were treated with different doses of lipopolysaccharide (LPS) from Escherichia coli to mimic sepsis in vitro. Western blot analysis was performed to confirm whether LPS-induced in vitro sepsis was correlated with the involvement of the Stat3/TLR4 signaling pathway. In addition, RAW 264.7 cells were infected with lentiviruses containing Wfdc21 shRNA to further confirm the role of Wfdc21 in the pathogenesis of sepsis.

Results

We found that Wfdc21 level was elevated in the CLP-induced animal model and LPS-treated RAW264.7 cells. Furthermore, the downregulation of Wfdc21 modulated the concentration of pro-inflammatory factors in LPS-treated macrophages, such as IL-1β and TNF-α, in LPS-treated macrophages. This regulatory effect was mediated through the Stat3/TLR4 signaling pathway, since Wfdc21 can regulate p-Stat3 and TLR4 levels in LPS-treated macrophages.

Conclusions

Wfdc21 plays a critical role in the pathogenesis of sepsis and may provide a therapeutic target for sepsis treatment.

Complement and sepsis-induced heart dysfunction

It is well known that cardiac dysfunction develops during sepsis in both humans and in rodents (rats, mice). These defects appear to be reversible, since after "recovery" from sepsis, cardiac dysfunction disappears and the heart returns to its function that was present before the onset of sepsis. Our studies, using in vivo and in vitro models, have demonstrated that C5a and its receptors (C5aR1 and C5aR2) play key roles in cardiac dysfunction developing during sepsis. Use of a neutralizing antibody to C5a largely attenuates cardiac dysfunction and other adverse events developing during sepsis. The molecular basis for cardiac dysfunctions is linked to generation of C5a and its interaction with C5a receptors present on surfaces of cardiomyocytes (CMs). It is established that C5a interactions with C5a receptors leads to significant reductions involving faulty contractility and relaxation in CMs. In addition, C5a interactions with C5a receptors on CMs results in reductions in Na⁺/K⁺-ATPase in CMs. This ATPase is essential for intact action potentials in CMs. The enzymatic activity and protein for this ATPase were strikingly reduced in CMs during sepsis by unknown mechanisms. In addition, C5a interactions with C5aRs also caused reductions in CM homeostatic proteins that regulate cytosolic [Ca²⁺]i in CMs: sarco/endoplasmic reticulum Ca²⁺-ATPase2 (SERCA2) and Na⁺/Ca²⁺ exchanger (NCX). In the absence of C5a receptors, defects in SERCA2 and NCX in CMs after sepsis are strikingly attenuated. These observations suggest new strategies to protect the heart from dysfunction developing during sepsis.

Mortality rates increase dramatically below a systolic blood pressure of 105-mm Hg in septic surgical patients

BACKGROUND

This study used a prospective surgical database, to investigate the level of systolic blood pressure (SBP) at which the mortality rates begin to increase in septic surgical patients.

METHODS

All acute, septic general surgical patients older than 15 years of age admitted between January 2012 and January 2015 were included in these analyses.

RESULTS

Of a total of 6,020 adult surgical patients on the database, 3,053 elective patients, 1,664 nonseptic, 52 duplicates, and 11 patients with missing SBP were excluded to leave a cohort of 1,232 acute, septic surgical patients. The median age (intraquartile range [IQR]): 48 (32 to 62) and roughly 50:50 sex ratio (620 female: 609 male). Most of the patients were African: 988 (80.2%) followed by Asians (128 or 10.4%). More than two-thirds (852 or 69.2%) of the patient cohort underwent some form of surgery, and 152 or 12.3% required intensive care unit (ICU) admission. The median length of ICU stay (IQR) was 2 (1 to 4.5) days. The median length of total hospital stay (IQR) was 4 (2 to 9) days. The median SBP (IQR) on admission was 122 (107 to 138). A total of 167 patients died (13.6%). Those that died did have a significantly lower mean SBP compared with the survivors (116 vs 125, P <. 001). Six of 10 patients (60%) with a SBP less than 70 died. The receiver operating characteristic analysis suggests an optimal SBP cut-off of 111 when predicting mortality (area under the receiver operating characteristic curve: .6 [.551, .65]). This cut-off yields a moderate sensitivity (70%), high positive predictive value (90%) but low specificity, and negative predictive value when predicting mortality. Based on this optimal cut-off, 388 or 31.5% of the patients would be classified as shocked. The inflection curve below with fitted nonlinear curve (95% confidence intervals) clearly shows the upward change in observed mortality frequency at lower systolic and base excess (ie base deficit) values. Shocked patients had a significantly higher frequency of mortality (20% vs 11%, P < .001), a significantly higher median lactate (1.9 vs 1.5, P < .001), and mean base deficit (-2.8 vs -1.0, P = .001). No significant difference in mean age, ICU admission, duration of ICU admission, and total length of hospital stay was observed by shocked status.

CONCLUSIONS

Our data suggest that patients who die have a significantly lower SBP and clinically significant hypotension in sepsis with regard to increased mortality risk begins at a level of ∼111-mm Hg. This finding needs to be incorporated into bundles of care for surgical sepsis.

Anti-TNF-α therapy for patients with sepsis: a systematic meta-analysis

OBJECTIVE

In humans, the role of anti-tumour necrosis factor (TNF)-α therapy in severe sepsis and septic shock is debatable. The aim of this meta-analysis was to determine the efficacy of anti-TNF-α therapies against placebo in patients with severe sepsis or septic shock.

METHODS

A structured literature search was undertaken to identify randomised controlled trials (RCTs) conducted in patients with severe sepsis or septic shock receiving anti-TNF-α therapy or placebo. A meta-analysis on relative risk (OR) with a 95% confidence interval (95% CI) was performed.

RESULTS

Seventeen studies with a total of 8971 patients were included. When all forms of anti-TNF-α therapy were pooled together, there was a significant reduction of 28-day all-cause mortality with respect to placebo (OR = 0.91, 95% CI: 0.83-0.99; p = 0.04). Subgroup analysis showed that anti-TNF-α antibodies (monoclonal and polyclonal) reduced mortality (OR = 0.90, 95% CI: 0.81-0.99; p = 0.04). Monoclonal antibodies enhanced survival (OR = 0.91, 95% CI: 0.82-1.00; p = 0.05), while polyclonal antibodies or receptor blockers did not enhance survival (OR = 0.71, 95% CI: 0.39-1.28, p = 0.25; OR = 0.95, 95% CI: 0.78-1.17, p = 0.65). There was a trend towards better survival in patients with high levels of IL-6 (> 1000 pg/ml) and patients with shock if they were treated with anti-TNF-α therapy (OR = 0.85, 95% CI: 0.72-1.00; OR = 0.80, 95% CI: 0.62-1.04). Publication bias and statistical heterogeneity (I(2)  < 50% and p > 0.1) were absent. Sensitivity analysis suggests that these results are highly stable.

CONCLUSIONS

This meta-analysis suggests that in patients with severe sepsis (before shock), immunotherapy with anti-TNF-α monoclonal antibodies reduces overall mortality. In patients with shock or high levels of IL-6 (> 1000 pg/ml), anti-TNF-α therapy may improve survival.

Determination of the safety and efficacy of therapeutic neutralization of tumor necrosis factor-α (TNF-α) using AZD9773, an anti-TNF-α immune Fab, in murine CLP sepsis

OBJECTIVE AND DESIGN

TNF-α neutralization is associated with increased mortality in mouse cecal ligation puncture (CLP) models. AZD9773 is an ovine polyclonal human TNF-α immune Fab, with pharmacological properties that differ from previously studied anti-TNF-α agents. We explored the safety and efficacy of therapeutically administered AZD9773 in mouse CLP sepsis.

METHODS

A moderate/severe-grade CLP model resulting in 20-30 % 5-day survival and a mild-grade CLP model resulting in ~70 % 5-day survival were established in human TNF-α transgene/murine TNF null (Tg1278/-/-) mice.

TREATMENT

Mice received saline resuscitation and imipenem administration every 12 h (0-72 h post-CLP). AZD9773 (or DigiFab control) was dosed 24, 36, 48 and 60 h post-CLP.

RESULTS

Therapeutic dosing of AZD9773 in moderate/severe-grade CLP resulted in significantly increased survival (>70 %) compared with DigiFab (27 %, P < 0.05). Therapeutic dosing of AZD9773 in mild-grade CLP did not significantly affect survival outcome compared with DigiFab or imipenem alone (~60-70 % survival).

CONCLUSIONS

These data demonstrate that TNF-α neutralization can improve survival in moderate/severe CLP sepsis. TNF-α suppression in mild-grade models was not associated with survival benefit and did not increase 5-day mortality. These findings suggest that therapeutic benefit following TNF-α attenuation in models of sepsis may depend on model severity.

Population pharmacokinetic/pharmacodynamic modelling of the anti-TNF-α polyclonal fragment antibody AZD9773 in patients with severe sepsis

AZD9773 is an ovine-derived, polyclonal, anti-tumour necrosis factor-alpha (TNF-α) antibody fragment. Using data from an AZD9773 Phase IIa study in patients with severe sepsis (clinicaltrials.gov: NCT00615017), a population pharmacokinetic/pharmacodynamic (PK/PD) model was developed. The model assessed the influence of various covariates on the PK of AZD9773 and the relationship between AZD9773 exposure and serological TNF-α concentration. A linear two-compartment model was used to describe AZD9773 concentration-time data. A stepwise covariate analysis was performed on the PK parameters. Subsequently, the serological TNF-α concentrations and drug effect were captured using an indirect response model, with a variable production rate of TNF-α described by a quadratic function. Creatinine clearance (CrCL) was the only covariate with a significant effect on the PK of AZD9773. A typical patient's drug clearance varied with CrCL; the relationship was non-linear. Diagnostic analysis of the PK/PD model showed that the fit was good, both across cohorts and in AZD9773-treated versus placebo patients. Serological TNF-α concentrations and the reduction of measurable serum TNF-α by AZD9773 were well characterized across all the cohorts evaluated in the Phase IIa study. This population PK/PD model was subsequently used to simulate alternative dosing options for a Phase IIb study (clinicaltrials.gov: NCT01145560).

A placebo-controlled, double-blind, dose-escalation study to assess the safety, tolerability and pharmacokinetics/pharmacodynamics of single and multiple intravenous infusions of AZD9773 in patients with severe sepsis and septic shock

Introduction

Tumor necrosis factor-alpha (TNF-α), an early mediator in the systemic inflammatory response to infection, is a potential therapeutic target in sepsis. The primary objective of this study was to determine the safety and tolerability of AZD9773, an ovine, polyclonal, anti-human TNF-α Fab preparation, in patients with severe sepsis. Secondary outcomes related to pharmacokinetic (PK) and pharmacodynamic (PD) parameters.

Methods

In this double-blind, placebo-controlled, multicenter Phase IIa study, patients were sequentially enrolled into five escalating-dose cohorts (single doses of 50 or 250 units/kg; multiple doses of 250 units/kg loading and 50 units/kg maintenance, 500 units/kg loading and 100 units/kg maintenance, or 750 units/kg loading and 250 units/kg maintenance). In each cohort, patients were randomized 2:1 to receive AZD9773 or placebo.

Results

Seventy patients received AZD9773 (n = 47) or placebo (n = 23). Baseline characteristics were similar across cohorts. Mean baseline APACHE score was 25.9. PK data demonstrated an approximately proportional increase in concentration with increasing dose and a terminal half-life of 20 hours. For the multiple-dose cohorts, serum TNF-α concentrations decreased to near-undetectable levels within two hours of commencing AZD9773 infusion. This suppression was maintained in most patients for the duration of treatment. AZD9773 was well tolerated. Most adverse events were of mild-to-moderate intensity and considered by the reporting investigator as unrelated to study treatment.

Conclusions

The safety, PK and PD data support the continued evaluation of AZD9773 in larger Phase IIb/III studies.

Matrix metalloproteinases as drug targets in infections caused by gram-negative bacteria and in septic shock

The mammalian immune system is optimized to cope effectively with the constant threat of pathogens. However, when the immune system overreacts, sepsis, severe sepsis, or septic shock can develop. Despite extensive research, these conditions remain the leading cause of death in intensive care units. The matrix metalloproteinases (MMPs) constitute a family of proteases that are expressed in developmental, physiological, and pathological processes and also in response to infections. Studies using MMP inhibitors and MMP knockout mice indicate that MMPs play essential roles in infection and in the host defense against infection. This review provides a brief introduction to some basic concepts of infections caused by gram-negative bacteria and reviews reports describing MMP expression and inhibition, as well as studies with MMP-deficient mice in models of infection caused by gram-negative bacteria and of septic shock. We discuss whether MMPs should be considered novel drug targets in infection and septic shock.