Polymyxin-B hemoperfusion inactivates circulating proapoptotic factors

High-volume hemofiltration does not protect human kidney endothelial and tubular epithelial cells from septic plasma-induced injury

High volume hemofiltration (HVHF) could remove from plasma inflammatory mediators involved in sepsis-associated acute kidney injury (SA-AKI). The IVOIRE trial did not show improvements of outcome and organ dysfunction using HVHF. The aim of this study was to evaluate in vitro the biological effects of plasma of patients treated by HVHF or standard volume hemofiltration (SVHF). We evaluated leukocyte adhesion, apoptosis and functional alterations of endothelial cells (EC) and tubular epithelial cells (TEC). In vitro data were correlated with plasma levels of TNF-α, Fas-Ligand (FasL), CD40-Ligand (CD40L), von Willebrand Factor (vWF) and endothelial-derived microparticles. An experimental model of in vitro hemofiltration using LPS-activated blood was established to assess cytokine mass adsorption during HVHF or SVHF. Plasma concentrations of TNF-ɑ, FasL, CD40L and von Willebrand Factor (vWF) were elevated at the start (d1h0) of both HVHF and SVHF, significantly decreased after 6 h (d1h6), remained stable after 12 h (d1h12) and then newly increased at 48 h (d3h0). Plasma levels of all these molecules were similar between HVHF- and SVHF-treated patients at all time points considered. In addition, the levels of endothelial microparticles remained always elevated, suggesting the presence of a persistent microvascular injury. Plasma from septic patients induced leukocyte adhesion on EC and TEC through up-regulation of adhesion receptors. Moreover, on EC, septic plasma induced a cytotoxic and anti-angiogenic effect. On TEC, septic plasma exerted a direct pro-apoptotic effect via Fas up-regulation and caspase activation, loss of polarity, altered expression of megalin and tight junction molecules with an impaired ability to internalize albumin. The inhibition of plasma-induced cell injury was concomitant to the decrease of TNF-α, Fas-Ligand and CD40-Ligand levels. The protective effect of both HVHF and SVHF was time-limited, since a further increase of circulating mediators and plasma-induced cell injury was observed after 48 h (d3h0). No significant difference of EC/TEC damage were observed using HVHF- or SVHF-treated plasma. The in vitro hemofiltration model confirmed the absence of a significant modulation of cytokine adsorption between HVHF and SVHF. In comparison to SVHF, HVHF did not increase inflammatory cytokine clearance and did not reverse the detrimental effects of septic plasma-induced EC and TEC injury. Further studies using adsorptive membranes are needed to evaluate the potential role of high dose convective therapies in the limitation of the harmful activity of plasma soluble factors involved in SA-AKI.Trial registration IVOIRE randomized clinical trial; ClinicalTrials.gov (NCT00241228) (18/10/2005).

The role of polymyxin B-immobilized hemoperfusion in reducing mortality and enhancing hemodynamics in patients with sepsis and septic shock: A systematic review and meta-analysis

Purpose

Polymyxin B-immobilized hemoperfusion (PMX-HP) is a therapeutic strategy for removing circulating endotoxins from patients with sepsis or septic shock. However, the survival advantage of PMX-HP treatment remains controversial for patients with sepsis/septic shock. Therefore, this study collected all the clinical trials to assess the effect and the safety of PMX-HP treatment.

Methods

PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for eligible trials fromtheir inception through June 30, 2023. All clinical trials that investigated the effect of polymyxin B hemoperfusion in patients who died with sepsis or septic shock within 28-day mortality were eligible. The Cochrane Risk of Bias Assessment instrument and the ROBINS-I tool were used to assess the risk of bias.

Results

A total of 30 trials, including 25680 adult patients, were included. PMX-HP decreased 28-day mortality (OR 0.75, 95 % CI 0.65-0.88; p＜0.00001). Subgroup analysis revealed that 28-day mortality was significantly reduced after PMX-HP treatment in the mixed infection site group and in the age under 70 years old group. PMX-HP might also lower endotoxin levels (MD -1.22, 95 % CI -1.62 - 0.81, p < 0.00001) and improve SOFA scores (MD -2.11, 95 % CI -3.80- 0.43, p = 0.01). PMX-HP was not linked to the development of significant adverse events (p = 0. 05).

Conclusion

Our findings suggest that PMX-HP therapy can reduce 28-day mortality in individuals with sepsis or septic shock. The therapeutic effect may be due to the ability of PMX-HP to lower endotoxin levels and enhance hemodynamics. However, further assessment of the clinical effects of PMX-HP on sepsis or septic shock is required.

New insights into kidney disease after COVID-19 infection and vaccination: histopathological and clinical findings

In addition to its pulmonary effects, coronavirus disease 2019 (COVID-19) has also been found to cause acute kidney injury (AKI), which has been linked to high mortality rates. In this review, we collected data from 20 clinical studies on post-COVID-19-related AKI and 97 cases of AKI associated with COVID-19 vaccination. Acute tubular injury was by far the most common finding in the kidneys of patients with COVID-19-related AKI. Among patients hospitalized for COVID-19, 34.0% developed AKI, of which 59.0%, 19.1% and 21.9% were Stages 1, 2 and 3, respectively. Though kidney disease and other adverse effects after COVID-19 vaccination overall appear rare, case reports have accumulated suggesting that COVID-19 vaccination may be associated with a risk of subsequent kidney disease. Among the patients with post-vaccination AKI, the most common pathologic findings include crescentic glomerulonephritis (29.9%), acute tubular injury (23.7%), IgA nephropathy (18.6%), antineutrophil cytoplasmic autoantibody-associated vasculitis (17.5%), minimal change disease (17.5%) and thrombotic microangiopathy (10.3%). It is important to note that crescentic glomerulonephritis appears to be more prevalent in patients who have newly diagnosed renal involvement. The proportions of patients with AKI Stages 1, 2 and 3 after COVID-19 vaccination in case reports were 30.9%, 22.7% and 46.4%, respectively. In general, clinical cases of new-onset and recurrent nephropathy with AKI after COVID-19 vaccination have a positive prognosis. In this article, we also explore the underlying pathophysiological mechanisms of AKI associated with COVID-19 infection and its vaccination by describing key renal morphological and clinical features and prognostic findings.

Clinical implications of endotoxin activity and Polymyxin-B hemoperfusion in critically ill patients with septic cardiomyopathy: A single-center, retrospective, observational study

BACKGROUND

To explore the association between endotoxin activity (EA) and septic cardiomyopathy (SCM), the relationship between endotoxin removal by Polymyxin-B hemoperfusion (PMX-HP) and recovery from SCM (R-SCM), and the correlation between R-SCM and the 28-day mortality in septic patients admitted to the intensive care unit (ICU).

METHODS

Observational study that included patients admitted to two ICUs of a tertiary university hospital between April 2011 and December 2019, who received PMX-HP for sepsis/septic shock. The SCM and R-SCM were assessed by transthoracic echocardiography.

RESULTS

Among 148 patients, SCM was diagnosed in 60 (46%) of them and had no relationship with median EA (SCM group: 0.73; no-SCM group: 0.66, p = 0.48). Recovery from SCM was observed in 24 patients (49%) and was independently associated with the PMX-HP (OR 4.19, 95%CI [1.22, 14.3]; p = 0.02) and the SAPS2 II score (OR 0.94, 95%CI [0.9, 0.98]; p = 0.006). In the SCM group, the 28-day mortality was 60% and was independently predicted by R-SCM (OR 0.02, 95%CI [0.001, 0.3] p = 0.005) and SAPS II score (OR 1.11, 95%CI [1.01, 1.23] p = 0.037).

CONCLUSIONS

In septic patients, EA was not associated with SCM. However, endotoxin removal by Polymyxin-B hemoperfusion was associated with recovery from cardiomyopathy, which was a predictor of lower 28-day mortality.

Blood Purification for Adult Patients With Severe Infection or Sepsis/Septic Shock: A Network Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

This study aimed to conduct a comprehensive and updated systematic review with network meta-analysis (NMA) to assess the outcome benefits of various blood purification modalities for adult patients with severe infection or sepsis.

DATA SOURCES

We conducted a search of PubMed, MEDLINE, clinical trial registries, Cochrane Library, and Embase databases with no language restrictions.

STUDY SELECTION

Only randomized controlled trials (RCTs) were selected.

DATA EXTRACTION

The primary outcome was overall mortality. The secondary outcomes were the length of mechanical ventilation (MV) days and ICU stay, incidence of acute kidney injury (AKI), and kidney replacement therapy requirement.

DATA SYNTHESIS

We included a total of 60 RCTs with 4,595 participants, comparing 16 blood purification modalities with 17 interventions. Polymyxin-B hemoperfusion (relative risk [RR]: 0.70; 95% CI, 0.57-0.86) and plasma exchange (RR: 0.61; 95% CI, 0.42-0.91) were associated with low mortality (very low and low certainty of evidence, respectively). Because of the presence of high clinical heterogeneity and intransitivity, the potential benefit of polymyxin-B hemoperfusion remained inconclusive. The analysis of secondary outcomes was limited by the scarcity of available studies. HA330 with high-volume continuous venovenous hemofiltration (CVVH), HA330, and standard-volume CVVH were associated with shorter ICU stay. HA330 with high-volume CVVH, HA330, and standard-volume CVVH were beneficial in reducing MV days. None of the interventions showed a significant reduction in the incidence of AKI or the need for kidney replacement therapy.

CONCLUSIONS

Our NMA suggests that plasma exchange and polymyxin-B hemoperfusion may provide potential benefits for adult patients with severe infection or sepsis/septic shock when compared with standard care alone, but most comparisons were based on low or very low certainty evidence. The therapeutic effect of polymyxin-B hemoperfusion remains uncertain. Further RCTs are required to identify the specific patient population that may benefit from extracorporeal blood purification.

Extracorporeal blood purification therapies for sepsis-associated acute kidney injury in critically ill patients: expert opinion from the SIAARTI-SIN joint commission

Sepsis-Associated Acute Kidney Injury is a life-threatening condition leading to high morbidity and mortality in critically ill patients admitted to the intensive care unit. Over the past decades, several extracorporeal blood purification therapies have been developed for both sepsis and sepsis-associated acute kidney injury management. Despite the widespread use of extracorporeal blood purification therapies in clinical practice, it is still unclear when to start this kind of treatment and how to define its efficacy. Indeed, several questions on sepsis-associated acute kidney injury and extracorporeal blood purification therapy still remain unresolved, including the indications and timing of renal replacement therapy in patients with septic vs. non-septic acute kidney injury, the optimal dialysis dose for renal replacement therapy modalities in sepsis-associated acute kidney injury patients, and the rationale for using extracorporeal blood purification therapies in septic patients without acute kidney injury. Moreover, the development of novel extracorporeal blood purification therapies, including those based on the use of adsorption devices, raised the attention of the scientific community both on the clearance of specific mediators released by microorganisms and by injured cells and potentially involved in the pathogenic mechanisms of organ dysfunction including sepsis-associated acute kidney injury, and on antibiotic removal. Based on these considerations, the joint commission of the Italian Society of Anesthesiology and Critical Care (SIAARTI) and the Italian Society of Nephrology (SIN) herein addressed some of these issues, proposed some recommendations for clinical practice and developed a common framework for future clinical research in this field.

Bacterial extracellular vesicles repress the vascular protective factor RNase1 in human lung endothelial cells

BACKGROUND

Sepsis is one of the leading causes of death worldwide and characterized by blood stream infections associated with a dysregulated host response and endothelial cell (EC) dysfunction. Ribonuclease 1 (RNase1) acts as a protective factor of vascular homeostasis and is known to be repressed by massive and persistent inflammation, associated to the development of vascular pathologies. Bacterial extracellular vesicles (bEVs) are released upon infection and may interact with ECs to mediate EC barrier dysfunction. Here, we investigated the impact of bEVs of sepsis-related pathogens on human EC RNase1 regulation.

METHODS

bEVs from sepsis-associated bacteria were isolated via ultrafiltration and size exclusion chromatography and used for stimulation of human lung microvascular ECs combined with and without signaling pathway inhibitor treatments.

RESULTS

bEVs from Escherichia coli, Klebsiella pneumoniae and Salmonella enterica serovar Typhimurium significantly reduced RNase1 mRNA and protein expression and activated ECs, while TLR2-inducing bEVs from Streptococcus pneumoniae did not. These effects were mediated via LPS-dependent TLR4 signaling cascades as they could be blocked by Polymyxin B. Additionally, LPS-free ClearColi™ had no impact on RNase1. Further characterization of TLR4 downstream pathways involving NF-кB and p38, as well as JAK1/STAT1 signaling, revealed that RNase1 mRNA regulation is mediated via a p38-dependent mechanism.

CONCLUSION

Blood stream bEVs from gram-negative, sepsis-associated bacteria reduce the vascular protective factor RNase1, opening new avenues for therapeutical intervention of EC dysfunction via promotion of RNase1 integrity. Video Abstract.

Crosstalk between COVID-19 Infection and Kidney Diseases: A Review on the Metabolomic Approaches

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19, a respiratory disorder. Various organ injuries have been reported in response to this virus, including kidney injury and, in particular, kidney tubular injury. It has been discovered that infection with the virus does not only cause new kidney disease but also increases treatment difficulty and mortality rates in people with kidney diseases. In individuals hospitalized with COVID-19, urinary metabolites from several metabolic pathways are used to distinguish between patients with acute kidney injury (AKI) and those without. This review summarizes the pathogenesis, pathophysiology, treatment strategies, and role of metabolomics in relation to AKI in COVID-19 patients. Metabolomics is likely to play a greater role in predicting outcomes for patients with kidney disease and COVID-19 with varying levels of severity in the near future as data on metabolic profiles expand rapidly. Here, we also discuss the correlation between COVID-19 and kidney diseases and the available metabolomics approaches.

Ceftazidime/Avibactam, Polymyxin or Tigecycline as a Rescue Strategy for the Treatment of Carbapenem-Resistant Klebsiella pneumoniae in Bloodstream Infection: A Retrospective Cohort Study

Objective

To analyze the clinical characteristics, outcomes, and risk factors of patients treated with ceftazidime/avibactam, polymyxin, or tigecycline (CPT) compared with those receiving a conventional therapy (CT) (ie, imipenem, levofloxacin, or gentamicin).

Methods

A single-center retrospective cohort study included patients with carbapenem-resistant Klebsiella pneumoniae bloodstream infection (CRKP-BSI) treated at one Chinese tertiary hospital between March 2012 and November 2022 was performed. Clinical characteristics, outcomes, and risk factors of patients treated with CPT or CT were compared. Predictors of 30-day mortality of patients with CRKP-BSI were also analysed in our study.

Results

Among 184 recruited patients with CRKP-BSI, 39.7% (73/184) were treated with CPT, while 60.3% (111/184) were treated with CT. Compared to patients treated with CT, patients treated with CPT had worse conditions, as evidenced by a higher rate of underlying diseases and invasive procedures; however, they also had a better prognosis and lower rates of 14-day treatment failure (p = 0.024). In addition, univariate analysis and multivariate analysis showed that SOFA score [odds ratio (OR) = 1.310, 95% confidence interval (CI) 1.157-1.483; p < 0.001] and cold weather (OR = 3.658, 95% CI 1.474-9.081; p = 0.005) were independent risk factors for 30-day mortality.

Conclusion

Compared to CRKP-BSI patients treated with CT, patients treated with CPT had worse conditions but better prognoses. CRKP-BSI occurred more frequently in hot weather; however, higher 30-day mortality was associated with cold weather. A randomized trial is needed to confirm these observational results.

Potential survival benefit and early recovery from organ dysfunction with polymyxin B hemoperfusion: perspectives from a real-world big data analysis and the supporting mechanisms of action

Background

Endotoxin (ET) removal therapy with polymyxin B-immobilized fiber column hemoperfusion (PMX-HP) has been used for the treatment of septic shock. Some observational studies reported clinical benefits, particularly in specific subgroups of patients. However, larger randomized controlled trial results have been disappointing.

Main body

The four studies that revealed the survival benefit of PMX-HP were based on the Japanese Diagnosis Procedure Combination (DPC) national inpatient database (J-DPC study). Nevertheless, one J-DPC study and a randomized controlled trial (RCT) conducted in France evaluated PMX-HP in patients with abdominal septic shock and did not report a significant survival benefit. In both studies, the severity of illness was too low to find substantial significant differences in mortality. The results of the J-DPC studies further suggest that some subpopulations of patients could benefit from PMX-HP. Based on these results, this review revisited prior RCTs and other large-scale studies on PMX-HP. In addition, four J-DPC studies and one large-scale study reported a survival benefit with PMX-HP. A secondary analysis of the EUPHRATES trial, the most recent double-blinded RCT of PMX-HP conducted in North America, suggested a survival benefit in patients with high levels of endotoxemia. In the J-DPC studies and the EUPHRATES trial, ventilator-free days, vasoactive drug-free days, and renal replacement-free days were significantly improved in the PMX-HP groups. These findings suggest that PMX-HP can contribute to early recovery from organ dysfunction. The reduction of supportive care likely provides important health and economic benefits for managing patients with septic shock. Finally, the blood levels of mediators or biomarkers related to respiratory, cardiovascular, and renal dysfunction have been reported to be normalized with PMX-HP.

Conclusions

These results support the biological rationale for the improvement in organ dysfunction observed in the J-DPC studies and other large-scale studies, including the EUPHRATES trial. Real-world evidence from large data sets suggests an appropriate patient population that are likely to benefit from the utility of PMX-HP for septic shock.

Acute Endotoxemia-Induced Respiratory and Intestinal Dysbiosis

Systemic inflammatory response syndrome (SIRS) is a severe condition characterized by systemic inflammation, which may lead to multiple organ failure, shock and death. SIRS is common in burn patients, pancreatitis and sepsis. SIRS is often accompanied by intestinal dysbiosis. However, the mechanism, role and details of microbiome alterations during the early phase of acute SIRS are not completely understood. The current study aimed to characterize the dynamic alterations of both the intestinal and respiratory microbiome at two timepoints during the early phase of acute SIRS (4 and 8 h after LPS) and link these to the host response in a mouse model of a LPS-induced lethal SIRS. Acute SIRS had no effect on the microbiome in the large intestine but induced a rapid dysbiosis in the small intestine, which resembled the microbiome alterations commonly observed in SIRS patients. Later in the disease progression, a dysbiosis of the respiratory microbiome was observed, which was associated with the MMP9 expression in the lungs. Although similar bacteria were increased in both the lung and the small intestine, no evidence for a gut-lung translocation was observed. Gut dysbiosis is commonly observed in diseases involving inflammation in the gut. However, whether the inflammatory response associated with SIRS and sepsis can directly cause gut dysbiosis was still unclear. In the current study we provide evidence that a LPS-induced SIRS can directly cause dysbiosis of the small intestinal and respiratory microbiome.

Interaction of Lipopolysaccharide-Spiked Blood with Anti-Fouling Polymyxin B-Modified Glass

Bacterial endotoxin, also known as lipopolysaccharide (LPS), plays a major role in the initiation of sepsis, a severe inflammatory condition. Removal of the toxin from blood is one accepted method of patient treatment. Polymyxin B (PMB)-modified columns have been employed successfully for this purpose via extra-corporeal blood-flow systems that incorporate a cartridge for toxin removal. Herein we demonstrate that PMB-modified glass beads are able to reduce the presence of LPS competitively with the equivalent fiber column used in a commercial cartridge. Analysis by gas chromatography-mass spectrometry and ELISA of released fatty acids from the toxin indicates that PMB does not physically capture or significantly remove LPS from the blood samples. In reality, interaction between the surface-bound PMB and the toxin may lead to disaggregation or monomerization of LPS aggregates. As aggregates are the bioactive form of LPS, it is possible that the monomerization of these entities may be the mechanism by which their toxicity is reduced. Moreover, this work indicates that LPS monomers are stabilized subsequent to disaggregation induced by PMB.

Pathophysiology of COVID-19-associated acute kidney injury

Although respiratory failure and hypoxaemia are the main manifestations of COVID-19, kidney involvement is also common. Available evidence supports a number of potential pathophysiological pathways through which acute kidney injury (AKI) can develop in the context of SARS-CoV-2 infection. Histopathological findings have highlighted both similarities and differences between AKI in patients with COVID-19 and in those with AKI in non-COVID-related sepsis. Acute tubular injury is common, although it is often mild, despite markedly reduced kidney function. Systemic haemodynamic instability very likely contributes to tubular injury. Despite descriptions of COVID-19 as a cytokine storm syndrome, levels of circulating cytokines are often lower in patients with COVID-19 than in patients with acute respiratory distress syndrome with causes other than COVID-19. Tissue inflammation and local immune cell infiltration have been repeatedly observed and might have a critical role in kidney injury, as might endothelial injury and microvascular thrombi. Findings of high viral load in patients who have died with AKI suggest a contribution of viral invasion in the kidneys, although the issue of renal tropism remains controversial. An impaired type I interferon response has also been reported in patients with severe COVID-19. In light of these observations, the potential pathophysiological mechanisms of COVID-19-associated AKI may provide insights into therapeutic strategies.

Up-to-date information on polymyxin B-immobilized fiber column direct hemoperfusion for septic shock

Endotoxin adsorption therapy by polymyxin B-immobilized fiber column direct hemoperfusion (PMX-DHP) has been used for the treatment of septic shock patients. Endotoxin, an outer membrane component of Gram-negative bacteria, plays an important role in the pathogenesis of septic shock. Endotoxin triggers a signaling cascade for leukocytes, macrophage, and endothelial cells to secrete various mediators including cytokines and nitric oxide, leading to septic shock and multiple organ dysfunction syndrome. PMX-DHP directly adsorbed not only endotoxin but also monocytes and anandamide. It reduced blood levels of inflammatory cytokines such as interleukin (IL)-1, IL-6, tumor necrosis factor-alpha and IL-17A, adhesion molecules, plasminogen activator inhibitor 1, and high mobility group box-1. As a result, PMX-DHP increased blood pressure and reduced the dose of vasoactive-inotropic agents. PMX-DHP improved monocyte human leukocyte antigen-DR expression in patients with severe sepsis and septic shock. A post hoc analysis of EUPHRATES (Evaluating the Use of Polymyxin B Hemoperfusion in Randomized Controlled Trial of Adults Treated for Endotoxemia and Septic Shock) trial has shown that PMX-DHP significantly reduced 28-day mortality compared with the control group in septic shock patients with endotoxin activity assay level between 0.60 and 0.89. Longer duration of PMX-DHP may be another strategy to bring out the beneficial effects of PMX-DHP. Further studies are needed to confirm the efficacy of PMX-DHP treatment for septic shock.

Therapeutic Rationale for Endotoxin Removal with Polymyxin B Immobilized Fiber Column (PMX) for Septic Shock

Endotoxin removal therapy with polymyxin B immobilized fiber column (PMX) has been clinically applied for sepsis and septic shock patients since 1994. The effectiveness and usefulness of this therapy have been demonstrated for more than a quarter of a century. However, a documented survival benefit has not yet been demonstrable in a large, multicenter, randomized and controlled trial. Following the findings derived from a large sepsis clinical trial with PMX in North America, a new trial is ongoing to determine if PMX has a long-term survival benefit when administered to septic patients. Another approach to support a survival benefit from intervention with PMX is to utilize a detailed analysis available from a large clinical data base. The endotoxin adsorption capacity of PMX columns in vitro and the effectiveness of PMX columns can be further demonstrable in animal models. The capability of PMX and details of its mechanism of action to intervene in the sepsis cascade and impede organ dysfunction in septic patients is not fully understood. The surface antigen expression in monocytes and neutrophils are improved after PMX therapy. Immunomodulatory effects as a result of endotoxin removal and/or other mechanisms of action have been suggested. These effects and other potential immune effects may explain some of the improved effects upon organ dysfunction of sepsis and septic shock patients. Endotoxemia may be involved in the pathophysiology of other diseases than sepsis. A rapid diagnostic method to detect and target endotoxemia could allow us to practice precision medicine and expand the clinical indications of endotoxin removal therapy.

Effect of Extracorporeal Blood Purification on Mortality in Sepsis: A Meta-Analysis and Trial Sequential Analysis

OBJECTIVE

The objective of this study was to conduct a meta-analysis and trial sequential analysis (TSA) of published randomized controlled trials (RCTs) to determine whether mortality benefit exists for extracorporeal blood purification techniques in sepsis.

DATA SOURCES

A systematic search on MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials for RCTs was performed.

STUDY SELECTION

RCTs investigating the effect of extracorporeal blood purification device use on mortality among critically ill septic patients were selected.

DATA EXTRACTION

Mortality was assessed using Mantel-Haenszel models, and I2 was used for heterogeneity. Data are presented as odds ratios (OR); 95% confidence intervals (CIs); p values; I2. Using the control event mortality proportion, we performed a TSA and calculated the required information size using an anticipated intervention effect of a 14% relative reduction in mortality.

DATA SYNTHESIS

Thirty-nine RCTs were identified, with 2,729 patients. Fourteen studies used hemofiltration (n = 789), 17 used endotoxin adsorption devices (n = 1,363), 3 used nonspecific adsorption (n = 110), 2 were cytokine removal devices (n = 117), 2 used coupled plasma filtration adsorption (CPFA) (n = 207), 2 combined hemofiltration and perfusion (n = 40), and 1 used plasma exchange (n = 106). On conventional meta-analysis, hemofiltration (OR 0.56 [0.40-0.79]; p < 0.001; I2 = 0%), endotoxin removal devices (OR 0.40 [0.23-0.67], p < 0.001; I2 = 71%), and nonspecific adsorption devices (OR 0.32 [0.13-0.82]; p = 0.02; I2 = 23%) were associated with mortality benefit, but not cytokine removal (OR 0.99 [0.07-13.42], p = 0.99; I2 = 64%), CPFA (OR 0.50 [0.10-2.47]; p = 0.40; I2 = 64%), or combined hemofiltration and adsorption (OR 0.71 [0.13-3.79]; p = 0.69; I2 = 0%). TSA however revealed that based on the number of existing patients recruited for RCTs, neither hemofiltration (TSA-adjusted CI 0.29-1.10), endotoxin removal devices (CI 0.05-3.40), nor nonspecific adsorption devices (CI 0.01-14.31) were associated with mortality benefit.

CONCLUSION

There are inadequate data at present to conclude that the use of extracorporeal blood purification techniques in sepsis is beneficial. Further adequately powered RCTs are required to confirm any potential mortality benefit, which may be most evident in patients at greatest risk of death.

Effectiveness of polymyxin B-immobilized hemoperfusion against sepsis and septic shock: A systematic review and meta-analysis

PURPOSE

To evaluate the efficacy and safety of Polymyxin B-immobilized hemoperfusion (PMX-HP) against sepsis or septic shock.

METHODS

We searched databases (PubMed, EMBASE and Cochrane Library) to identify eligible randomized controlled trials (RCTs). The primary outcomes we included in this review were mortality at the longest follow-up available and serious adverse events associated with treatments. We used the Cochrane risk of bias assessment tool to evaluate risk of bias. Trial Sequential Analysis (TSA) was performed to assess the conclusion reached in our research.

RESULTS

Thirteen studies including 1163 patients were identified. Use of PMX-HP could reduce overall mortality [relative risk (RR) 0.68, 95% confidence interval (CI) 0.51-0.91, P = 0.01]. An interesting finding was that the mortality of patients in Acute Physiology and Chronic Health Evaluation (APACHE II) scores <25 group (RR 0.64, 95% CI 0.52-0.78, P < 0.0001) and sepsis group (RR 0.48, 95% CI 0.32-0.72, P = 0.0003) significantly decreased after PMX-HP treatment. The result also showed that PMX-HP could reduce endotoxin levels [Standardized mean difference (SMD) -1.53, 95% CI -2.92- -0.13, P = 0.03] and improve mean arterial pressure (SMD 1.07, 95% CI 0.14-2.01, P = 0.02). Serious adverse events between the PMX-HP group and standard therapy group were not significantly different (RR 2.16, 95% CI 0.97-4.80, I² = 0%, P = 0.06). However, TSA did not provide conclusive evidence and more high quality RCTs were required.

CONCLUSION

Using PMX-HP to treat patients with less severe sepsis can reduce overall mortality and is safe. Treatment efficacy may benefit from the reduction of endotoxin level and the improvement of hemodynamics. More high quality RCTs are required to further evaluate the clinical role of PMX-HP against severe sepsis or septic shock.

Blood Purification and Mortality in Sepsis and Septic Shock: A Systematic Review and Meta-analysis of Randomized Trials

BACKGROUND

Sepsis and septic shock are severe inflammatory conditions related to high morbidity and mortality. We performed a systematic review with meta-analysis of randomized trials to assess whether extracorporeal blood purification reduces mortality in this setting.

METHODS

Electronic databases were searched for pertinent studies up to January 2019. We included randomized controlled trials on the use of hemoperfusion, hemofiltration without a renal replacement purpose, and plasmapheresis as a blood purification technique in comparison to conventional therapy in adult patients with sepsis and septic shock. The primary outcome was mortality at the longest follow-up available. We calculated relative risks and 95% CIs. The grading of recommendations assessment, development and evaluation methodology for the certainty of evidence was used.

RESULTS

Thirty-seven trials with 2,499 patients were included in the meta-analysis. Hemoperfusion was associated with lower mortality compared to conventional therapy (relative risk = 0.88 [95% CI, 0.78 to 0.98], P = 0.02, very low certainty evidence). Low risk of bias trials on polymyxin B immobilized filter hemoperfusion showed no mortality difference versus control (relative risk = 1.14 [95% CI, 0.96 to 1.36], P = 0.12, moderate certainty evidence), while recent trials found an increased mortality (relative risk = 1.22 [95% CI, 1.03 to 1.45], P = 0.02, low certainty evidence); trials performed in the United States and Europe had no significant difference in mortality (relative risk = 1.13 [95% CI, 0.96 to 1.34], P = 0.15), while trials performed in Asia had a positive treatment effect (relative risk = 0.57 [95% CI, 0.47 to 0.69], P < 0.001). Hemofiltration (relative risk = 0.79 [95% CI, 0.63 to 1.00], P = 0.05, very low certainty evidence) and plasmapheresis (relative risk = 0.63 [95% CI, 0.42 to 0.96], P = 0.03, very low certainty evidence) were associated with a lower mortality.

CONCLUSIONS

Very low-quality randomized evidence demonstrates that the use of hemoperfusion, hemofiltration, or plasmapheresis may reduce mortality in sepsis or septic shock. Existing evidence of moderate quality and certainty does not provide any support for a difference in mortality using polymyxin B hemoperfusion. Further high-quality randomized trials are needed before systematic implementation of these therapies in clinical practice.

Mechanisms of sepsis-induced immunosuppression and immunological modification therapies for sepsis

Surgical injury can be a life-threatening complication, not only due to the injury itself, but also due to immune responses to the injury and subsequent development of infections, which readily result in sepsis. Sepsis remains the leading cause of death in most intensive care units. Unfavorable outcomes of several high-profile trials in the treatment of sepsis have led researchers to state that sepsis studies need a new direction. The immune response that occurs during sepsis is characterized by a cytokine-mediated hyper-inflammatory phase, which most patients survive, and a subsequent immunosuppressive phase. Therefore, therapies that improve host immunity might increase the survival of patients with sepsis. Many mechanisms are responsible for sepsis-induced immunosuppression, including apoptosis of immune cells, increased regulatory T cells and expression of programmed cell death 1 on CD4+ T cells, and cellular exhaustion. Immunomodulatory molecules that were recently identified include interleukin-7, interleukin-15, and anti-programmed cell death 1. Recent studies suggest that immunoadjuvant therapy is the next major advance in sepsis treatment.

Extended Sessions of Polymyxin-B Immobilized Fiber Column Hemoperfusion Ameliorate Renal Outcome and Mortality in Septic Shock with Acute Kidney Injury

Background/Aims: Polymyxin-B (PMX) treatment has been reported to decrease mortality in patients with septic shock and acute kidney injury (AKI). In this study, we aimed to evaluate whether extended sessions of PMX (Ext-PMX) immobilized fiber column hemoperfusion ameliorate clinical outcomes in patients complicated with septic shock and AKI without surgical control. Methods: Twenty-two patients with nonsurgical septic shock and AKI who received PMX were included. They were divided according to the duration of PMX treatment: Ext-PMX and standard PMX (Std-PMX). Results: The mean blood pressure increased and inotrope requirement decreased within 24 h after PMX initiation. The median value of predicted mortality was 52.5%, and the ­28-day mortalities in the Ext-PMX and Std-PMX groups were 44.4 and 75% respectively. Renal replacement therapy (RRT) was also initiated in 17 patients, and renal insufficiency was recovered. Conclusion: Ext-PMX combined with RRT improved clinical outcomes in patients with nonsurgical septic shock and AKI.

pH after the first session of direct hemoperfusion with polymyxin B-immobilized fibers predicts mortality in patients with sepsis and septic shock

BACKGROUND

The definition of sepsis was updated to sepsis-3 in February 2016. Currently, direct hemoperfusion therapy using the polymyxin B-immobilized fiber cartridge (PMX-DHP) is widely performed to treat sepsis and septic shock. However, the prognostic factors of PMX-DHPs in patients with sepsis using the new definition are unclear. We retrospectively assessed prognostic factors in patients who had received PMX-DHP therapy for sepsis and septic shock.

METHODS

We included 71 patients with severe infection who underwent PMX-DHP treatment from January 2006 to August 2015 in this study. Participants were re-evaluated according to the criteria of sepsis-3. The patients were divided into two groups based on having survived (n = 59) or not survived (n = 12) for 28 days after PMX-DHP treatment. Clinical data before and after PMX-DHP treatment were compared between the two groups.

RESULTS

Non-survivors showed a lower Glasgow Coma Scale (GCS) score before PMX-DHP treatment compared with 28-day survivors [12 (6-14) vs 14 (12-15), P < 0.01]. Furthermore, pH after the first PMX-DHP session was significantly lower in non-survivors than in survivors (7.28 ± 0.23 vs 7.39 ± 0.06, P = 0.03). Multivariate logistic regression analysis showed that only lower pH after the first PMX-DHP session was a predictor of 28-day mortality independent of age, sex, GCS score, and mean arterial pressure (odds ratio per pH of 0.01, 0.93; 95% confidence interval, 0.83-0.99; P = 0.02).

CONCLUSION

The pH after the first PMX-DHP session is an independent risk factor for mortality in patients receiving PMX-DHP for sepsis and septic shock.

Modulation by Polymyxin-B Hemoperfusion of Inflammatory Response Related to Severe Peritonitis

Conflicting results have been reported on the influence of Polymyxin-B hemoperfusion treatment on systemic inflammation markers. The aim of the study was to assess in a randomized control trial the influence on plasma cytokine concentrations of Polymyxin-B hemoperfusion in septic shock due to peritonitis. A panel of 10 pro- or anti-inflammatory cytokines was measured in 213 patients with peritonitis-induced septic shock enrolled in the randomized trial ABDOMIX testing the impact of 2 Polymyxin-B hemoperfusion sessions with standard treatment. Gram-negative bacteria were identified in 69% of patients. In the overall population, baseline plasma cytokine concentrations were not different between the two groups. Circulating tumor necrosis factor-α, interleukin (IL)-1β, IL-10, IL-6, and IL-1RA decreased significantly over time in both groups (P <0.0001 for all in controls, and P = 0.0002, 0.003, and <0.0001 in patients treated with Polymyxin-B hemoperfusion). IL-17A decreased significantly in patients treated with Polymyxin B hemoperfusion (P = 0.045) but not in controls. At the end of the second Polymyxin-B hemoperfusion session or at corresponding time in controls, plasma levels of cytokines did not differ between the two groups. Similar results were found in the subgroup of patients with gram-negative peritonitis who completed two Polymyxin-B hemoperfusion sessions. These results do not support a significant influence of Polymyxin-B hemoperfusion on circulating cytokines assessed except for IL-17A which clinical significance remains to be elucidated.

Polymyxin B-immobilized hemoperfusion and mortality in critically ill adult patients with sepsis/septic shock: a systematic review with meta-analysis and trial sequential analysis

PURPOSE

Polymyxin B-immobilized hemoperfusion (PMX-HP) is an adjuvant therapy for sepsis or septic shock that clears circulating endotoxin. Prior trials have shown that PMX-HP improves surrogate endpoints. We aimed to conduct an evidence synthesis to evaluate the efficacy and safety of PMX-HP in critically ill adult patients with sepsis or septic shock.

METHODS

We searched for randomized controlled trials (RCTs) in MEDLINE, EMBASE, the Cochrane Library, the Health Technology Assessment Database, CINAHL, "Igaku Chuo Zasshi", the National Institute of Health Clinical Trials Register, the World Health Organization International Clinical Trials Registry Platform, the University Hospital Medical Information Network Clinical Trials Registry, the reference lists of retrieved articles, and publications by manufacturers of PMX-HP. The primary outcomes were 28-day all-cause mortality, the number of patients with at least one serious adverse event, and organ dysfunction scores. The GRADE methodology for the certainty of evidence was used.

RESULTS

Six trials (857 participants; weighted mean age 62.5 years) proved eligible. Patient-oriented primary outcomes were assessed. The pooled risk ratio (RR) for 28-day mortality associated with PMX-HP was 1.03 [95% confidence interval (CI) 0.78-1.36; I ² = 25%; n = 797]. The pooled RR for adverse events was 2.17 (95% CI 0.68-6.94; I ² = 0%; n = 717). Organ dysfunction scores over 24-72 h after PMX-HP treatment did not change significantly (standardized mean difference - 0.26; 95% CI - 0.64 to 0.12; I ² = 78%; n = 797). The certainty of the body of evidence was judged as low for both benefit and harm using the GRADE methodology.

CONCLUSIONS

There is currently insufficient evidence to support the routine use of PMX-HP to treat patients with sepsis or septic shock.

REGISTRATION

PROSPERO International Prospective Register of Systematic Reviews (CRD42016038356).

Mechanisms of endothelial activation in sepsis and cell culture models to study the heterogeneous host response

Sepsis is currently viewed as a fundamental disintegration of control functions from intracellular signalling to immunoregulatory and neuroendocrine mechanisms. The immediate threat in sepsis is invasive infection, and the need to activate immune defense mechanisms to clear the pathogen before irreparable damage occurs. In the process of pathogen elimination, however, the systemic host response to infection may cause collateral damage to the endothelium and may lead to the destruction of host tissues.A number of experimental models have been developed to monitor endothelial activation and to study endothelial dysfunction under septic conditions. Here, we review the application of these models to assess the highly variable host response in sepsis and to investigate the efficacy of adsorbent-based extracorporeal therapies. We also highlight the need for efficient diagnostic tools, which are indispensable to select patients who are likely to benefit from distinct adjunctive therapies.

Polymyxin-B hemoperfusion in septic patients: analysis of a multicenter registry

Background

In 2010, the EUPHAS 2 collaborative group created a registry with the purpose of recording data from critically ill patients suffering from severe sepsis and septic shock treated with polymyxin-B hemoperfusion (PMX-HP) for endotoxin removal. The aim of the registry was to verify the application of PMX-HP in the daily clinical practice.

Methods

The EUPHAS 2 registry involved 57 centers between January 2010 and December 2014, collecting retrospective data of 357 patients (297 in Europe and 60 in Asia) suffering from severe sepsis and septic shock caused by proved or suspected infection related to Gram negative bacteria. All patients received atleast one cycle of extracorporeal endotoxin removal by PMX-HP.

Results

Septic shock was diagnosed in 305 (85.4 %) patients. The most common source of infection was abdominal (44.0 %) followed by pulmonary (17.6 %). Gram negative bacteria represented 60.6 % of the pathogens responsible of infection. After 72 h from the first cycle of PMX-HP, some of the SOFA score components significantly improved with respect to baseline: cardiovascular (2.16 ± 1.77 from 3.32 ± 1.29, p < 0.0001), respiratory (1.95 ± 0.95 from 2.40 ± 1.06, p < 0.001) and renal (1.84 ± 1.77 from 2.23 ± 1.62, p = 0.013). Overall 28-day survival rate was 54.5 % (60.4 % in abdominal and 47.5 % in pulmonary infection). Patients with abdominal infection treated with PMX-HP within 24 h from the diagnosis of septic shock had a 28-day survival rate of 64.5 %. Patients showing a significantly cardiovascular improvement after PMX-HP had a 28-survival rate of 75 % in comparison to the 39 % of patients who did not (p < 0.001). Cox regression analysis found the variation of cardiovascular, respiratory and coagulation SOFA to be independent covariates for 28-day survival. In European patients were observed a higher 28-day (58.8 vs. 34.5 %, p = 0.003), ICU (59 vs. 36.7 %, p = 0.006) and hospital survival rate (53.2 vs. 35 %, p = 0.02) than in Asian patients. However, the two populations were highly heterogeneous in terms of source of infection and severity scores at admission.

Conclusion

The EUPHAS 2 is the largest registry conducted outside Japan on the clinical use of PMX-HP in septic patients. Data analysis confirmed the feasibility of PMX-HP to treat septic patients in daily clinical practice, showing clinical benefits associated with endotoxin removal without significant adverse events related to the extracorporeal technique.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-016-0178-9) contains supplementary material, which is available to authorized users.

Polymyxin B hemoperfusion prevents acute kidney injury in sepsis model

BACKGROUND

Direct hemoperfusion with a polymyxin B-immobilized column (PMX-DHP) adsorbs endotoxin and has been used for the treatment of septic shock. Yet, the mechanisms by which PMX-DHP acts on acute kidney injury are only partially understood.

MATERIALS AND METHODS

Rats were anesthetized, tracheostomized, and placed on mechanical ventilation. The animals were randomized to three groups: a cecal ligation and puncture (CLP) + dummy-DHP group (n = 10), a CLP + PMX-DHP group (n = 10), and a sham group (n = 4). Four hours after CLP, a dummy-DHP or PMX-DHP was performed for 1 h. The heart rate, mean arterial pressure, arterial blood gases, and plasma concentrations of creatinine, lactate, potassium, interleukin (IL)-6, and IL-10 were measured at 0 h and 8 h. Eight hours after CLP, the kidney was harvested, and histopathologic examination was performed. The expressions of cleaved poly (ADP-ribose) polymerase (PARP) and nuclear factor (NF)-κB p65 were examined by immunohistochemistry. A terminal deoxynucleotide transferase dUTP nick-end labeling assay was performed to detect apoptotic nuclei in kidney sections.

RESULTS

PMX-DHP maintained hemodynamics and the acid-base balance and significantly (P < 0.05) decreased the plasma concentrations of lactate, creatinine, potassium, IL-6, and IL-10 compared with dummy-DHP. PMX-DHP significantly (P < 0.001) attenuated the expressions of cleaved PARP and NF-κB p65 in renal tubular cells and renal tubular cell apoptosis compared with dummy-DHP.

CONCLUSIONS

These findings suggest that PMX-DHP may protect against acute kidney injury not only by inhibiting the NF-κB signaling pathway but also by preventing renal tubular cell apoptosis.

Sepsis-induced acute kidney injury revisited: pathophysiology, prevention and future therapies

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a common complication in critically ill patients and is associated with increased morbidity and mortality. Sepsis is the most common cause of AKI. Considerable evidence now suggests that the pathogenic mechanisms of sepsis-induced AKI are different from those seen in other causes of AKI. This review focuses on the recent advances in this area and discusses possible therapeutic interventions that might derive from these new insights into the pathogenesis of sepsis-induced AKI.

RECENT FINDINGS

The traditional paradigm that sepsis-induced AKI arises from ischemia has been challenged by recent evidence that total renal blood flow in is not universally impaired during sepsis, and AKI can develop in the presence of normal or even increased renal blood flow. Animal and human studies suggest that adaptive responses of tubular epithelial cells to injurious signals are responsible for renal dysfunction. Simultaneously occurring renal inflammation and microcirculatory dysfunction further amplify these mechanisms.

SUMMARY

An understanding of the pathologic mechanisms of sepsis-induced AKI emphasizes the important role of maladaptive responses to the septic insult. Preventive and therapeutic measures should be based on counteracting these maladaptive responses of tubular epithelial cells, inflammation, and microvascular dysfunction.

Podocyte apoptosis is prevented by blocking the Toll-like receptor pathway

High serum lipopolysaccharide (LPS) activity in normoalbuminuric patients with type 1 diabetes (T1D) predicts the progression of diabetic nephropathy (DN), but the mechanisms behind this remain unclear. We observed that treatment of cultured human podocytes with sera from normoalbuminuric T1D patients with high LPS activity downregulated 3-phosphoinositide-dependent kinase-1 (PDK1), an activator of the Akt cell survival pathway, and induced apoptosis. Knockdown of PDK1 in cultured human podocytes inhibited antiapoptotic Akt pathway, stimulated proapoptotic p38 MAPK pathway, and increased apoptosis demonstrating an antiapoptotic role for PDK1 in podocytes. Interestingly, PDK1 was downregulated in the glomeruli of diabetic rats and patients with type 2 diabetes before the onset of proteinuria, further suggesting that reduced expression of PDK1 associates with podocyte injury and development of DN. Treatment of podocytes in vitro and mice in vivo with LPS reduced PDK1 expression and induced apoptosis, which were prevented by inhibiting the Toll-like receptor (TLR) signaling pathway with the immunomodulatory agent GIT27. Our data show that LPS downregulates the cell survival factor PDK1 and induces podocyte apoptosis, and that blocking the TLR pathway with GIT27 may provide a non-nephrotoxic means to prevent the progression of DN.

Renal replacement therapy in acute kidney injury: controversy and consensus

Renal replacement therapies (RRTs) represent a cornerstone in the management of severe acute kidney injury. This area of intensive care and nephrology has undergone significant improvement and evolution in recent years. Continuous RRTs have been a major focus of new technological and treatment strategies. RRT is being used increasingly in the intensive care unit, not only for renal indications but also for other organ-supportive strategies. Several aspects related to RRT are now well established, but others remain controversial. In this review, we review the available RRT modalities, covering technical and clinical aspects. We discuss several controversial issues, provide some practical recommendations, and where possible suggest a research agenda for the future.

High cut-off hemofiltration versus standard hemofiltration: a pilot assessment of effects on indices of apoptosis

OBJECTIVES

To measure plasma pro-apoptotic and pro-necrotic activity in severe acute kidney injury (AKI) patients within a randomized controlled trial of continuous veno-venous hemofiltration with high cut-off filters (CVVH-HCO) versus standard filters (CVVH-Std).

METHODS

We measured pro-apoptotic and pro-necrotic plasma activity by trypan blue exclusion cell viability assay, detection of DNA fragmentation, and by determination of caspase-3 activity and annexin V-based apoptosis and necrosis detection assay.

RESULTS

Compared to no apoptosis or necrosis after incubation with healthy plasma, 14-18% of cells showed apoptosis and 4-8% showed necrosis after incubation with plasma from AKI patients. When comparing different measures of pro-apoptotic or pro-necrotic activity, CVVH-HCO and CVVH-Std showed no differential effects on such activity, which remained high over the first 3 days of treatment. However, using annexin V-FITC, there was a significant drop in pro-apoptotic activity across the filter for the CVVH-HCO group (p = 0.043) but not for the CVVH-Std group (p = 0.327) and a significant difference between the two groups (CVVH-HCO vs. CVVH-Std p = 0.006).

CONCLUSIONS

Patients with severe AKI have increased pro-apoptotic and pro-necrotic activity. Although on single-pass effect assessment, CVVH-HCO was superior to CVVH-Std in decreasing annexin V-FITC-assessed pro-apoptotic activity, there was no overall attenuation of such activity during the first 3 days of treatment.

Polymyxin B hemoperfusion: a mechanistic perspective

Direct hemoperfusion therapy with polymyxin B immobilized fiber cartridge (PMX-DHP) is an established strategy in the treatment of septic shock in Japan and parts of Western Europe. PMX-DHP is currently the subject of a pivotal North American randomized controlled trial (EUPHRATES) in patients with septic shock and confirmed endotoxemia, as measured by the endotoxin activity assay. The major mechanism of action of this therapy is the removal of circulating endotoxin. High affinity binding of circulating endotoxin by the PMX-DHP column may decrease circulating endotoxin levels by up to 90% after two standard treatments. Basic research has shown reductions in circulating cytokine levels and in renal tubular apoptosis. Clinical research has shown that PMX-DHP therapy results in hemodynamic improvements, improvements in oxygenation, renal function, and reductions in mortality. Further research is needed to further define additional patient populations with endotoxemia that may benefit from PMX-DHP therapy as well as to further elucidate dosing, timing, and additional information on mechanisms of action. This review will present the mechanistic rationale for this targeted strategy of endotoxin removal using PMX-DHP in endotoxemic septic patients, highlighting both the specific effects of the therapy and the evidence accumulated so far of clinical improvement following this therapy in terms of recovery of organ function.

Pro-inflammatory effects of matrix metalloproteinase 7 in acute inflammation

Matrix metalloproteinase 7 (MMP7) is a member of the MMP family. In the small intestine, MMP7 is responsible for activating α-defensins, which are broad-spectrum anti-microbial peptides produced by the Paneth cells. We report that MMP7(-/-) mice are resistant to LPS-induced lethality and that this resistance is correlated with reduced levels of systemic cytokines. LPS induced the upregulation and activation of MMP7 in the small intestine, degranulation of the Paneth cells, and induction of intestinal permeability in MMP7(+/+) mice. In MMP7(-/-) mice, both LPS-induced intestinal permeability and consequent bacterial translocation to the mesenteric lymph nodes were reduced. Based on gene expression analysis and evaluation of intestinal damage, we attribute the protected state of MMP7(-/-) mice to reduced intestinal inflammation. Interestingly, we found that different α-defensins, namely Crp1 (DEFA1) and Crp4 (DEFA4), can stimulate IL-6 release in macrophages and ileum explants in a TLR4 independent way. We conclude that absence of MMP7 protects mice from LPS-induced intestinal permeability and lethality, and suggest that MMP7-activated α-defensins, in addition to their previously recognized bactericidal and anti-inflammatory roles, may exhibit pro-inflammatory activities in the intestine by activating macrophages and amplifying the local inflammatory response in the gut, leading to intestinal leakage and subsequent increase in systemic inflammation.

Polymyxin B hemoperfusion in clinical practice: the picture from an unbound collaborative registry

After the publication of the EUPHAS trial, the clinical use of polymyxin B hemoperfusion (Toraymyxin®) increased significantly in Italy. Nevertheless, no structured data collections have been carried out to underline the characteristics of treated patients. Therefore, a collaborative registry of clinical data was promoted among users in order to better define the structure of the prospective data collection named the EUPHAS2 project. Neither inclusion criteria nor therapeutic constraints were imposed, highlighting adherence to clinical evidence provided by previous randomized controlled trials, and also unusual or borderline practice in the selection of patients for polymyxin B-based cartridges (PMX-DHP). This first retrospective phase of data collection included patients with severe sepsis and septic shock treated with Toraymyxin over the last 3 years, up to July 2013. Thirty-one hospitals participated in the EUPHAS2 study, collecting data on 306 patients. Enrolled patients were grouped according to the main source of sepsis: abdominal (41.8%) and nonabdominal (58.2%). The abdominal patients had characteristics well matching those selected for the EUPHAS randomized controlled trial in terms of time-to-enrolment, severity of the illness, 28-day mortality and in-hospital mortality. Their 28-day mortality rate was 35% with a significant reduction of the Sequential Organ Failure Assessment Score (SOFA) score after 72 h of treatment (p < 0.001). Patients with nonabdominal sepsis were heterogeneous and only a few of them had their endotoxin activity tested in a manner not allowing a reliable evaluation of the real efficacy of the treatment and organ dysfunction control. Their 28-day mortality rate was 49% and the SOFA score did not significantly change before and after treatment. In conclusion, clinical experience confirms the results of the original EUPHAS randomized trial in terms of outcome for patients with abdominal severe sepsis. Specific studies focused on a population of patients with Gram-negative infections of nonabdominal origin are needed before recommending treatment with Toraymyxin as an effective therapy.

Heart-kidney crosstalk and role of humoral signaling in critical illness

Organ failure in the heart or kidney can initiate various complex metabolic, cell-mediated and humoral pathways affecting distant organs, contributing to the high therapeutic costs and significantly higher morbidity and mortality. The universal outreach of cells in an injured state has myriad consequences to distant organ cells and their milieu. Heart performance and kidney function are closely interconnected and communication between these organs occurs through a variety of bidirectional pathways. The term cardiorenal syndrome (CRS) is often used to describe this condition and represents an important model for exploring the pathophysiology of cardiac and renal dysfunction. Clinical evidence suggests that tissue injury in both acute kidney injury and heart failure has immune-mediated inflammatory consequences that can initiate remote organ dysfunction. Acute cardiorenal syndrome (CRS type 1) and acute renocardiac syndrome (CRS type 3) are particularly relevant in high-acuity medical units. This review briefly summarizes relevant research and focuses on the role of signaling in heart-kidney crosstalk in the critical care setting.

Immunomodulation in sepsis: the role of endotoxin removal by polymyxin B-immobilized cartridge

Severe sepsis results in high morbidity and mortality. Immunomodulation strategies could be an adjunctive therapy to treat sepsis. Endotoxin is a component of gram-negative bacteria and plays an important role in the pathogenesis of septic shock when it is recognized by immune cells. Removal of endotoxin could be an effective adjunctive approach to the management of sepsis. Devices to adsorb endotoxin or inflammatory cytokines have been designed as a strategy to treat severe sepsis, especially sepsis caused by gram-negative bacteria. Polymyxin B-immobilized cartridge has been successfully used to treat patients with sepsis of abdominal origin. Although this cartridge was conceived to adsorb endotoxin, several other immunological mechanisms have been elucidated, and this device has also yielded promising results in patients with nonseptic respiratory failure. In this paper, we summarize the immune modulation actions of Polymyxin B-immobilized cartridge to explore its potential usefulness beyond endotoxin elimination.

[Usefulness of haemoperfusion in the treatment of the severe septic patient: an update]

Haemoperfusion is an extracorporeal technique that removes endotoxin and/or inflammatory mediators by means of an adsorptive mechanism during the passage of the blood through a porous filter. Most of the studies in the literature use polymyxin B as the adsorptive agent. This treatment is based on the assumption that the removal of endotoxin and inflammatory mediators from the circulation attenuates the inflammatory response in sepsis. This review summarizes the theoretical basis, and the experimental and clinical results published to date with the use of haemoperfusion. Although most of the studies show positive results, some doubts have arisen about the suitability of the methods described (small number of cases, low quality of the experimental design, and excessive mortality in the control groups). There are also some inconsistencies regarding the theoretical basis of its use (lack of positive effects after the removal of endotoxin from the circulation using alternative mechanisms, discrepancies regarding the best moment to initiate the therapy, unexplained beneficial effects in the absence of increased endotoxin levels). It is the opinion of the authors that haemoperfusion represents a promising therapy for the treatment of sepsis, but consider that its usefulness requires confirmation in well designed studies before being included in protocols.

Matrix metalloproteinase 13 modulates intestinal epithelial barrier integrity in inflammatory diseases by activating TNF

Several pathological processes, such as sepsis and inflammatory bowel disease (IBD), are associated with impairment of intestinal epithelial barrier. Here, we investigated the role of matrix metalloproteinase MMP13 in these diseases. We observed that MMP13^−/− mice display a strong protection in LPS- and caecal ligation and puncture-induced sepsis. We could attribute this protection to reduced LPS-induced goblet cell depletion, endoplasmic reticulum stress, permeability and tight junction destabilization in the gut of MMP13^−/− mice compared to MMP13^+/+ mice. Both in vitro and in vivo, we found that MMP13 is able to cleave pro-TNF into bioactive TNF. By LC-MS/MS, we identified three MMP13 cleavage sites, which proves that MMP13 is an alternative TNF sheddase next to the TNF converting enzyme TACE. Similarly, we found that the same mechanism was responsible for the observed protection of the MMP13^−/− mice in a mouse model of DSS-induced colitis. We identified MMP13 as an important mediator in sepsis and IBD via the shedding of TNF. Hence, we propose MMP13 as a novel drug target for diseases in which damage to the gut is essential.

Unravelling the enigma of proteinuria in burn patients

Hu and coworkers in the previous issue of Critical Care provide evidence for the clinical relevance of proteinuria in the outcome of burn patients. Proteinuria is a common finding after severe burns, appears within a short period and is detectable for several weeks. Proteinuria ranging from 0.5 to 3 to 4 g/day is initially of mixed type, then, after a week, gradually changes to tubular proteinuria. The clinical role of proteinuria is still unclear, mainly due to a lack of data on its pathogenesis. Recent studies have demonstrated an association between proteinuria and incidence of inhalation injury, sepsis, acute kidney injury and mortality rate. Proteinuria is considered the mirror of increased systemic capillary permeability, and possibly a direct marker of glomerular and tubular injury. Circulating plasma inflammatory mediators and pro-apoptotic factors reflecting burn injury, sepsis and acute kidney injury can affect the viability and function of tubular cells and podocytes. These studies highlight that proteinuria in burn patients should receive due consideration.

Renal cell apoptosis and new treatment options in sepsis-induced acute kidney injury

Sepsis is a common and important cause of mortality in critically ill patients. Acute kidney injury (AKI) is one of the most important factors determining morbidity and mortality in the prognosis of sepsis. Recent studies have indicated that the pathogenetic mechanism in septic AKI is totally different from that in non-septic AKI. Our understanding of sepsis-associated AKI pathophysiology is shifting from renal vasoconstriction, ischemia, and acute tubular necrosis to heterogeneous vasodilation, hyperemia, and acute tubular apoptosis. Especially, apoptosis is gradually gaining importance in the understanding of the development of renal injury. The frequency of renal tubular apoptosis on biopsies of septic patients has been pointed out in recently published studies. Apoptosis can be triggered by ischemia, exogen toxins, or endogen mediators. It has been shown in some animal models that hyperglycemia, which is common in critically ill patients, causes apoptosis in renal tubular cells. New treatment options have emerged in the light of recent findings. Ghrelin that inhibits pro-inflammatory cytokines, caspase inhibitors that block the apoptotic pathway, and suppression of anti-inflammatory reactions are under study. Among the existing methods of treatment, usage of arginine, which is a vasopressor agent, ventilation with a low tidal volume, and hemofiltration methods cleaning toxic mediators from the circulation should be considered in the first place. Hyperglycemia treatment is of major importance, since, besides its anti-inflammatory effect, it has a protective role on the kidney. Regarding pathogenesis, rates of morbidity and mortality are aimed to be reduced through the new agents of therapy that have been studied on.

Translocation of dendrin to the podocyte nucleus in acute glomerular injury in patients with IgA nephropathy

BACKGROUND

It has been reported that podocytopenia has been occurring with increasing disease severity in patients with IgA nephropathy (IgAN). Dendrin is localized at the slit diaphragm (SD) in podocytes. We showed that dendrin translocates to the nucleus of injured podocytes in experimental nephritis and the nuclear dendrin promotes podocyte apoptosis. It is still unknown whether dendrin translocates from the SD to podocyte nucleus in IgAN. We investigated the presence of nuclear dendrin in patients with IgAN and the association between the translocated dendrin to the podocyte nucleus and disease activity.

METHODS

Fourteen adult patients with IgAN were enrolled. The pathological parameters were analyzed. Immunostaining of renal biopsy specimens and urinary sediments from IgAN or minimal change nephrotic syndrome (MCNS) as the control was performed.

RESULTS

A positive correlation was observed between an acute extracapillary change and the number of dendrin-positive nuclei. The location of dendrin in the nuclei was found in urinary podocytes of IgAN. The number of dendrin-positive nuclei in urinary podocytes of IgAN was significantly higher than that of MCNS. Urinary podocytes, which expressed the apoptosis marker annexin V, were also detected in IgAN. The translocation of dendrin to the podocyte nucleus as well as strong cathepsin L staining were detected in the glomeruli of IgAN.

CONCLUSION

An increasing number of dendrin-positive nuclei in the glomeruli suggest acute glomerular injury in IgAN. Apoptotic podocytes were detectable in the urine of IgAN. It appears that the translocation of dendrin to the podocyte nuclei enhances podocyte apoptosis in acute glomerular injury and leads to podocytopenia in patients with IgAN.

Matrix metalloprotease 8-dependent extracellular matrix cleavage at the blood-CSF barrier contributes to lethality during systemic inflammatory diseases

Systemic inflammatory response syndrome (SIRS) is a highly mortal inflammatory disease, associated with systemic inflammation and organ dysfunction. SIRS can have a sterile cause or can be initiated by an infection, called sepsis. The prevalence is high, and available treatments are ineffective and mainly supportive. Consequently, there is an urgent need for new treatments. The brain is one of the first organs affected during SIRS, and sepsis and the consequent neurological complications, such as encephalopathy, are correlated with decreased survival. The choroid plexus (CP) that forms the blood-CSF barrier (BCSFB) is thought to act as a brain "immune sensor" involved in the communication between the peripheral immune system and the CNS. Nevertheless, the involvement of BCSFB integrity in systemic inflammatory diseases is seldom investigated. We report that matrix metalloprotease-8 (MMP8) depletion or inhibition protects mice from death and hypothermia in sepsis and renal ischemia/reperfusion. This effect could be attributed to MMP8-dependent leakage of the BCSFB, caused by collagen cleavage in the extracellular matrix of CP cells, which leads to a dramatic change in cellular morphology. Disruption of the BCSFB results in increased CSF cytokine levels, brain inflammation, and downregulation of the brain glucocorticoid receptor. This receptor is necessary for dampening the inflammatory response. Consequently, MMP8(+/+) mice, in contrast to MMP8(-/-) mice, show no anti-inflammatory response and this results in high mortality. In conclusion, we identify MMP8 as an essential mediator in SIRS and, hence, a potential drug target. We also propose that the mechanism of action of MMP8 involves disruption of the BCSFB integrity.

BCL2 genetic variants are associated with acute kidney injury in septic shock*

OBJECTIVE

Acute kidney injury frequently complicates septic shock and independently predicts mortality in this population. Clinical factors alone do not entirely account for differences in risk of acute kidney injury between patients. Genetic variants are likely to explain this differential susceptibility. To identify genetic variants linked to acute kidney injury susceptibility, we conducted a high-density genotyping association study in a large population of patients with septic shock.

DESIGN

Retrospective study.

SETTING

Tertiary academic medical center.

PATIENTS

One thousand two hundred and sixty-four patients with septic shock were analyzed to elucidate clinical risk factors associated with the development of acute kidney injury. Among them, 887 Caucasian patients were randomly split into discovery and validation cohorts and genotyped using the Illumina Human-CVD BeadChip (Illumina, San Diego, CA).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Six hundred and twenty-seven of the 1,264 patients with septic shock and 441 of the 887 patients with genotyping data developed acute kidney injury within the first 72 hrs of intensive care unit admission. Five single nucleotide polymorphisms were associated with acute kidney injury in both the discovery and validation cohorts. Two of these were in the BCL2 gene and both were associated with a decreased risk of acute kidney injury (rs8094315: odds ratio 0.61, p = .0002; rs12457893: odds ratio 0.67, p = .0002, both for combined data). Bcl-2 is involved in the apoptosis pathway, which has previously been implicated in acute kidney injury. Another single nucleotide polymorphism was in the SERPINA4 gene, whose protein product, kallistatin, has been linked to apoptosis in the kidney.

CONCLUSIONS

Large-scale genotyping reveals two single nucleotide polymorphisms in the BCL2 gene and a single nucleotide polymorphism in the SERPINA4 gene associated with a decreased risk of developing acute kidney injury, supporting the putative role of apoptosis in the pathogenesis of acute kidney injury.

Removal of increased circulating CD4+CD25+Foxp3+ regulatory T cells in patients with septic shock using hemoperfusion with polymyxin B-immobilized fibers

BACKGROUND

Although sepsis-induced immunosuppression has long been considered to be a factor in the late mortality of patients with sepsis, little is known about regulatory T cell (Treg)-mediated immunosuppression and the effect of polymyxin B-immobilized fiber (PMX-F) on sepsis-induced immunosuppression. We sought to investigate the role of CD4(+)CD25(+)Foxp3(+) Tregs in septic patients, and to evaluate the effect of hemoperfusion with PMX-F on the recovery from immunosuppression owing to septic shock.

METHODS

Thirty-two septic patients who had an identified focus of infection in the abdominal cavity were enrolled in this study. Peripheral blood mononuclear cells in the septic patients were examined to evaluate the roles of Tregs and the serum cytokine levels. We also examined the effects of PMX-F therapy on CD4(+) T cells, especially Tregs and serum cytokine levels in patients with septic shock.

RESULTS

The percentage of Tregs in the CD4(+) T-cell population, and the serum IL-6 and IL-10 levels, were significantly higher among patients with septic shock compared with those without septic shock, and PMX-F therapy significantly decreased the number of Tregs, as well as the serum IL-6 and IL-10 levels. Furthermore, a significant increase in the number of CD4(+) T cells, a significant decrease in the percentage of Tregs in the CD4(+) T-cell population, and a significant decrease in the serum IL-6 and IL-10 levels 24 hours after PMX-F therapy were observed in septic shock survivors compared with nonsurvivors.

CONCLUSION

We found a major increase in the percentage of Tregs in peripheral blood circulating CD4(+) T cells from patients with septic shock, and observed that the removal of Tregs by hemoperfusion with PMX-F might represent a novel strategy for inducing recovery from the immunosuppression associated with sepsis.