Interleukin-8 induces an elevation in the endotoxin activity assay (EAA) level: does the EAA truly measure the endotoxin level?

Effects of enhanced adsorption haemofiltration versus haemoadsorption in severe, refractory septic shock with high levels of endotoxemia: the ENDoX bicentric, randomized, controlled trial

BACKGROUND

Endotoxin adsorption is a promising but controversial therapy in severe, refractory septic shock and conflicting results exist on the effective capacity of available devices to reduce circulating endotoxin and inflammatory cytokine levels.

METHODS

Multiarm, randomized, controlled trial in two Swiss intensive care units, with a 1:1:1 randomization of patients suffering severe, refractory septic shock with high levels of endotoxemia, defined as an endotoxin activity ≥ 0.6, a vasopressor dependency index ≥ 3, volume resuscitation of at least 30 ml/kg/24 h and at least single organ failure, to a haemoadsorption (Toraymyxin), an enhanced adsorption haemofiltration (oXiris) or a control intervention. Primary endpoint was the difference in endotoxin activity at 72-h post-intervention to baseline. In addition, inflammatory cytokine, vasopressor dependency index and SOFA-Score dynamics over the initial 72 h were assessed inter alia.

RESULTS

In the 30, out of 437 screened, randomized patients (10 Standard of care, 10 oXiris, 10 Toraymyxin), endotoxin reduction at 72-h post-intervention-start did not differ among interventions (Standard of Care: 12 [1-42]%, oXiris: 21 [10-51]%, Toraymyxin: 23 [10-36]%, p = 0.82). Furthermore, no difference between groups could be observed neither for reduction of inflammatory cytokine levels (p = 0.58), nor for vasopressor weaning (p = 0.95) or reversal of organ injury (p = 0.22).

CONCLUSIONS

In a highly endotoxemic, severe, refractory septic shock population neither the Toraymyxin adsorber nor the oXiris membrane could show a reduction in circulating endotoxin or cytokine levels over standard of care. Trial registration ClinicalTrials.gov. NCT01948778. Registered August 30, 2013. https://clinicaltrials.gov/study/NCT01948778.

Comparison of different lots of endotoxin and evaluation of in vivo potency over time in the experimental human endotoxemia model

The experimental human endotoxemia model is used to study the systemic inflammatory response in vivo. The previously used lot of endotoxin, which was used for over a decade, is no longer approved for human use and a new Good Manufacturing Practices-grade batch has become available. We compared the inflammatory response induced by either bolus or continuous administration of either the previously used lot #1188844 or new lots of endotoxin (#94332B1 and #94332B4). Compared with lot #1188844, bolus administration of lot #94332B1 induced a more pronounced systemic inflammatory response including higher plasma levels of pro-inflammatory cytokines and more pronounced clinical signs of inflammation. In contrast, continuous infusion of lot #94332B4 resulted in a slightly less pronounced inflammatory response compared with lot #1188844. Furthermore, we evaluated whether lot #1188844 displayed in vivo potency loss by reviewing inflammatory parameters obtained from 17 endotoxemia studies performed in our centre between 2007 and 2016. Despite inter-study variability in endotoxemia-induced effects on temperature, heart rate, symptoms, and leukocyte counts, the magnitude of these effects did not decrease over time. In conclusion, although all lots of endotoxin induce a pronounced inflammatory response, the magnitude differs between lots. We observed no potency loss of endotoxin over time.

The state of the immune system in abdominal sepsis

AIM

To evaluate the prognostic value of cytokine profile, phagocytosis activity indices, endotoxin concentration and activity in blood in gram-negative sepsis.

MATERIALS AND METHODS

78 patients with abdominal sepsis were included in a one-center prospective cohort study, of them 45 died. All the patients were evaluated for the concentration of circulating cytokines (TNF-α, IFN-γ, IL-6, IL-8, IL-10), cellular molecules (CD3, CD45RO, CD95 and HLA-DR), bactericidal and phagocytic activity of neutrophils and endotoxin (lipopolysaccharide) level in peripheral blood.

RESULTS

The concentrations of all cytokines were slightly lower in the survivors. Significant differences were noted for TNF-α (p=0.001), IL-6 (p=0.001), and IL-8 (p=0.007). The expression of HLA-DR molecules was slightly higher (p=0.055), and CD95 was lower (p=0.146) in survivors than in the dead. However, the differences have not reached the required level of statistical significance. The phagocytic (p<0.001) and bactericidal activity (р=0.002 for stimulated activity and p=0.001 for spontaneous activity) of neutrophils is significantly different. In survived patients, we noted large values of stimulated bactericidal activity and phagocytic index than the dead. Level of spontaneous activity in survivors was lower. In subsequently deceased patients, the level of endotoxin load was higher than in the surviving patients: level of lipopolysaccharide concentration (p=0.002), endotoxin activity (p=0.032) and neutrophils activity (p=0.028).

CONCLUSION

Evaluation of cytokine levels is informative, but due to the high spread of indicators in different patients, should be carried out in the dynamics. The most informative prognostic parameters in sepsis are the concentration and activity of lipopolysaccharides (endotoxin), phagocytic and bactericidal activity of neutrophils. The EAA (endotoxin activity assay) assessment should be conducted in conjunction with the neutrophil "response" assessment.

IL-7 and procalcitonin are useful biomarkers in the comprehensive evaluation of the severity of acute cholangitis

BACKGROUND

The incidence of biliary tract infection (BTI), especially healthcare-associated cholangitis, is increasing. However, there are few reports concerning biomarkers of acute cholangitis. We therefore performed an exhaustive investigation of several biomarkers.

METHODS

We retrospectively measured 11 cytokines, six chemokines and procalcitonin (PCT), and endotoxin activity assay (EAA) values (IRB: 110512019) of 61 samples with acute cholangitis.

RESULT

The 28-day mortality rate was 9.8%. The levels of most cytokines and chemokines were significantly correlated with each other. A low IL-7 level was found to predict blood culture positivity. Low IL-7 level was also found to predict disseminated intravascular coagulation. Low IL-7 levels and a high PCT level were found to be predictors of severe cholangitis. The 28-day mortality in the group of patients with an IL-7 level of ≤6.0 and a PCT level of >0.5 was 18.2%. It was significantly higher than in the other group.

CONCLUSION

The combined use of IL-7 and PCT may be useful for evaluating severe acute cholangitis; these results may suggest that severe acute cholangitis is affected by immunosuppressive changes.

A comparative study of blood endotoxin detection in haemodialysis patients

BACKGROUND

Endotoxemia is commonly reported in patients receiving haemodialysis and implicated in the pathogenesis of systemic inflammation. The Limulus Amoebocyte Lysate (LAL) assay is the most commonly used blood endotoxin detection assay. Two kinetic variations of the assay are commercially available - the turbidimetric and chromogenic assay, it is unknown which assay is superior for endotoxin detection in uremic patients. Selection of the optimum LAL technique for endotoxin detection in haemodialysis patients is important to further understanding of the sequela of endotoxemia and development of endotoxin-lowering strategies in this population.

METHOD

A turbidimetric and chromogenic LAL assay from the same manufacturer were directly compared. We investigated the ability of both LAL assays to detect endotoxin in uremic plasma. Plasma samples from haemodialysis patients and healthy controls were spiked with endotoxin and percentage spike recovery for the chromogenic and turbidimetric assay was determined. Assay accuracy and precision were compared between both LAL assays.

RESULTS

The turbidimetric assay had greater accuracy than the chromogenic assay. Spike recovery was 113.8 % vs. 53.8 % for the turbidimetric and chromogenic assay respectively. Assay bias was higher in the chromogenic assay (-0.384EU/mL vs. 0.011EU/mL). The turbidimetric assay demonstrated greater precision compared to the chromogenic assay. Coefficient of variation ranged from 4.5 to 24.1 % for the turbidimetric assay and 25.8-26.5 % for the chromogenic assay.

CONCLUSION

The study findings suggest that the kinetic turbidimetric LAL assay has greater accuracy and precision than the chromogenic assay and is the optimum LAL technique for endotoxin detection in haemodialysis patients, though these findings should be verified using LAL reagents from other sources.

Endotoxemia-menace, marker, or mistake?

Endotoxemia is in its scientific ascendancy. Never has blood-borne, Gram-negative bacterial endotoxin (LPS) been invoked in the pathogenesis of so many diseases-not only as a trigger for septic shock, once its most cited role, but also as a contributor to atherosclerosis, obesity, chronic fatigue, metabolic syndrome, and many other conditions. Finding elevated plasma endotoxin levels has been essential supporting evidence for each of these links, yet the assays used to detect and quantitate endotoxin have important limitations. This article describes several assays for endotoxin in plasma, reviews what they do and do not measure, and discusses why LPS heterogeneity, LPS trafficking pathways, and host LPS inactivation mechanisms should be considered when interpreting endotoxin assay results.

The effects of direct hemoperfusion using a polymyxin B-immobilized column in a pig model of severe Pseudomonas aeruginosa pneumonia

Background

Hemoperfusion through a column containing polymyxin B-immobilized fiber (PMX-HP) is beneficial in abdominal sepsis. We assessed the effects of PMX-HP in a model of severe Pseudomonas aeruginosa pneumonia.

Methods

Eighteen pigs with severe P. aeruginosa pneumonia were mechanically ventilated for 76 h. Pigs were randomized to receive standard treatment with fluids and vasoactive drugs, or standard treatment with two 3-h PMX-HP sessions. Antibiotics against P. aeruginosa were never administered. We assessed endotoxemia through the endotoxin activity assay (EA). We measured the static lung elastance, ratio of arterial partial pressure per inspiratory fraction of oxygen (PaO₂/FIO₂), mean arterial pressure, cardiac output, systemic vascular resistance and inotropic score. Finally, every 24 h, we assessed complete blood count.

Results

In comparison with the control group, PMX-HP decreased percentage of circulating neutrophils from 47.4 ± 13.8 to 40.8 ± 11.5 % (p = 0.009). In a subgroup of animals with the worst hemodynamic impairment, EA in the control and PMX-HP groups was 0.50 ± 0.29 and 0.29 ± 0.14, respectively (p = 0.018). Additionally, in the control and PMX-HP groups, static lung elastance was 26.9 ± 8.7 and 25.3 ± 7.5 cm H₂O/L (p = 0.558), PaO₂/FIO₂ was 347.3 ± 61.9 and 356.4 ± 84.0 mmHg (p = 0.118), mean arterial pressure was 81.2 ± 10.3 and 81.6 ± 13.1 mmHg (p = 0.960), cardiac output was 3.30 ± 1.11 and 3.28 ± 1.19 L/min (p = 0.535), systemic vascular resistance was 1982.6 ± 608.4 and 2011.8 ± 750.0 dyne/s/cm^–5 (p = 0.939), and inotropic score was 0.25 ± 0.10 and 0.26 ± 0.18 (p = 0.864).

Conclusions

In mechanically ventilated pigs with severe P. aeruginosa pneumonia, PMX-HP does not have any valuable clinical benefit, and studies are warranted to fully evaluate a potential role of PMX-HP in septic shock associated with severe pulmonary infections.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-016-0155-3) contains supplementary material, which is available to authorized users.