In vitro comparison of the adsorption of inflammatory mediators by blood purification devices

Abstract

Background: Septic shock, a leading cause of acute kidney injury, induces release of pro-/anti-inflammatory mediators, leading to increased mortality and poor renal recovery. This is the first in vitro study directly comparing three single-use blood purification devices in terms of removing sepsis-associated mediators and endotoxins.

Methods: In vitro hemoperfusion was performed using oXiris^®, CytoSorb^®, and Toraymyxin^®. Heparinized human plasma from healthy volunteers was pre-incubated with pathologic quantities of inflammatory mediators and filtered in a closed-loop circulation model for 2 h. For each device, the removal of 27 inflammatory mediators was measured over time. Endotoxin removal mediated by oXiris and Toraymyxin was assessed using hemoperfusion over 6 h.

Results: Endotoxin (lipopolysaccharide) removal was most rapid with Toraymyxin; mean adsorptive clearance over the first 30 min was ~ 20 ml/min vs ~ 8 ml/min with oXiris (p < 0.05). There was minimal endotoxin removal with CytoSorb (1 ml/min). At 120 min, there was no significant difference between the endotoxin removal rates using oXiris (mean ± standard deviation, 68.0 ± 4.4%) and Toraymyxin (83.4 ± 3.8%); both were significantly higher vs CytoSorb (- 6.3 ± 4.9%; p < 0.05). Total removal with oXiris was 6.9 μg vs 9.7 μg for Toraymyxin, where the total lipopolysaccharide quantity introduced was approximately 15.8 μg. Removal rates of pro-/anti-inflammatory cytokines and other inflammatory mediators were similar between oXiris and CytoSorb and were higher with CytoSorb and oXiris vs Toraymyxin. Granulocyte colony-stimulating factor was only effectively adsorbed by CytoSorb (99.4%). Differences were detected between the adsorption mechanism of the devices; binding to oXiris was mainly ionic, while CytoSorb was hydrophobic. No specific protein adsorption was found qualitatively with Toraymyxin.

Conclusions: Adsorption rate kinetics varied for individual inflammatory mediators using the three blood purification devices. Mechanisms of adsorption differed between the devices. oXiris was the only device tested that showed both endotoxin and cytokine removal. oXiris showed similar endotoxin adsorption to Toraymyxin and similar adsorption to CytoSorb for the removal of other inflammatory mediators. Differences in device removal capacities could enable treatment to be more tailored to patients.

Keywords: Adsorption; Blood purification; Cytokines; Endotoxins; Removal rate; Septic shock; oXiris.

Fig. 1

Centers of activity in the inflammatory network driving sepsis. Abbreviations: C5a complement 5a, HMGB-1 high-mobility group box 1 protein, IL-17A interleukin-17A, MIF macrophage migration inhibitory factor, TLR4 Toll-like receptor 4 [6]

Fig. 2

LPS removal with oXiris, Toraymyxin, and CytoSorb. a LPS removal rate at t120 min. b LPS mean adsorption clearance over 30 min. Abbreviations: LPS lipopolysaccharide, N.S. not significant

Fig. 3

LPS adsorption isotherm obtained with oXiris and Toraymyxin blood purification devices. Abbreviation: LPS lipopolysaccharide

Fig. 4

Mean adsorption clearances over 30 min for the inflammatory mediators included in the study. Abbreviations: C3a complement 3a, C5a complement 5a, FGF fibroblast growth factor, G-CSF granulocyte-colony stimulating factor, HMGB-1 high-mobility group box 1 protein, IFN interferon, IL interleukin, IP interferon-induced protein, MCP monocyte chemoattractant protein, MIF macrophage migration inhibitory factor, MIP macrophage inflammatory protein, PAI plasminogen activator inhibitor, TNF tumor necrosis factor, Ra receptor agonist, α alpha, β beta, γ gamma

Fig. 5

Electrophoretic patterns of membrane elutes. Upper panel is a Tris-glycine gel; lower panel is a Tris-tricine gel