Cytokine removal in human septic shock: Where are we and where are we going?

Bioassay for Endothelial Damage Mediators Retrieved by Hemoadsorption

Hemoadsorption devices are used to treat septic shock by adsorbing inflammatory cytokines and as yet incompletely defined danger and pathogen associated molecular patterns. In an ideal case, hemoadsorption results in immediate recovery of microvascular endothelial cells’ (mEC) function and rapid recovery from catecholamine-dependency and septic shock. We here tested a single device, which consists of polystyrene-divinylbenzene core particles of 450 μm diameter with a high affinity for hydrophobic compounds. The current study aimed at the proof of concept that endothelial-specific damage mediators are adsorbed and can be recovered from hemoadsorption devices. Because of excellent clinical experience, we tested protein fractions released from a hemoadsorber in a novel endothelial bioassay. Video-based, long-term imaging of mEC proliferation and cell death were evaluated and combined with apoptosis and ATP measurements. Out of a total of 39 fractions recovered from column fractionation, we identified 3 fractions that caused i) inhibition of mEC proliferation, ii) increased cell death and iii) induction of apoptosis in mEC. When adding these 3 fractions to mEC, their ATP contents were reduced. These fractions contained proteins of approximately 15 kDa, and high amounts of nucleic acid, which was at least in part oxidized. The efficacy for endothelial cell damage prevention by hemoadsorption can be addressed by a novel endothelial bioassay and long-term video observation procedures. Protein fractionation of the hemoadsorption devices used is feasible to study and define endothelial damage ligands on a molecular level. The results suggest a significant effect by circulating nucleic acids – bound to an as yet undefined protein, which may constitute a major danger-associated molecular pattern (DAMP) in the exacerbation of inflammation when patients experience septic shock. Hemoadsorption devices may thus limit endothelial damage, through the binding of nucleic acid-bearing aggregates and thus contribute to improved endothelial barrier function.

Acute Kidney Injury in Critically Ill Children: A Retrospective Analysis of Risk Factors

INTRODUCTION

Children admitted to paediatric intensive care unit (PICU) are at risk of acute kidney injury (AKI). However, few paediatric studies have focused on the identification of factors potentially associated with the development of this condition. The aim of our study was to assess the incidence rate of AKI, identify risk factors, and evaluate clinical outcome in a large sample of critically ill children.

METHODS

This retrospective observational study was conducted including patients admitted to our PICU from January 2014 to December 2016. AKI was defined according to Kidney Disease: Improving Global Outcome criteria.

RESULTS

A total of 222 PICU patients out of 811 (27%) had AKI (stage I 39%, stage II 24%, stage III 37%). The most common PICU admission diagnoses in AKI cases were heart disease (38.6%), respiratory failure (16.8%) and postsurgical non-cardiac patients (11%). Hypoxic-ischaemic was the most frequent cause of AKI. Significant risk factors for AKI following multivariate analysis were age >2 months (OR 2.43; 95% CI 1.03-7.87; p = 0.05), serum creatinine at admission >44 µmol/L (OR 2.23; 95% CI 1.26-3.94; p = 0.006), presence of comorbidities (OR 1.84; 95% CI 1.03-3.30; p = 0.04), use of inotropes (OR 2.56; 95% CI 1.23-5.35; p= 0.012) and diuretics (OR 2.78; 95% CI 1.49-5.19; p = 0.001), exposure to nephrotoxic drugs (OR 1.66; 95% CI 1.01-2.91; p= 0.04), multiple organ dysfunction syndrome (OR 2.68; 95% CI 1.43-5.01; p = 0.002), and coagulopathy (OR 1.89; 95% CI 1.05-3.38, p = 0.03). AKI was associated with a significant longer PICU stay (median LOS of 8 days, interquartile range [IQR] 3-16, versus 4 days, IQR 2-8, in non-AKI patients; p < 0.001). The mortality rate resulted tenfold higher in AKI than non-AKI patients (12.6 vs. 1.2%; p < 0.001).

CONCLUSIONS

The incidence of AKI in critically ill children is high, with an associated increased length of stay and risk of mortality. In the PICU setting, risk factors of AKI are multiple and mainly associated with illness severity.

Endotoxin and cytokine reducing properties of the oXiris membrane in patients with septic shock: A randomized crossover double-blind study

BACKGROUND

Endotoxin induces an inflammatory response, with secondary release of cytokines, which can progress to shock and multiple organ failure. We explored whether continuous renal replacement therapy (CRRT) using a modified membrane (oXiris) capable of adsorption could reduce endotoxin and cytokine levels in septic patients.

METHODS

Sixteen patients requiring CRRT for septic shock-associated acute renal failure and who had endotoxin levels >0.03 EU/ml were prospectively randomized in a crossover double-blind design to receive CRRT with an oXiris filter or with a standard filter. Endotoxin and cytokine levels were measured at baseline and 1, 3, 8, 16 and 24 hours after the start of CRRT. Norepinephrine infusion rate and blood lactate levels were monitored.

RESULTS

During the first filter treatment period, endotoxin levels decreased in 7 of 9 (77.8%) oXiris filter patients, but in only 1 of 6 (16.7%) standard filter patients (P = 0.02). Levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-8 and interferon (IFN)γ decreased more with the oXiris filter than with the standard filter. Lactate concentration decreased with oXiris (-1.3[-2.2 to -1.1] mmol/l, P = 0.02), but not with the standard filter (+0.15[-0.95 to 0.6]). The norepinephrine infusion rate was reduced during oXiris CRRT, but not during standard filter CRRT. In the second filter treatment period, there was no significant reduction in endotoxin or cytokine levels in either group.

CONCLUSIONS

CRRT with the oXiris filter seemed to allow effective removal of endotoxin and TNF-α, IL-6, IL-8 and IFNγ in patients with septic shock-associated acute renal failure. This may be associated with beneficial hemodynamic effects.