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

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.

Adsorption as a Contributor for Inflammatory Mediators Removal by Different Hemofiltration Membranes: A Pilot Study.

Atherosclerosis is an important predictor of mortality in patients with chronic kidney disease (CKD) and is associated with a wide inflammatory response. The aim of this study is to evaluate in vitro how different membranes can remove mediators associated with this pathology in a closed loop dialysis model. We performed experimental hemofiltration in vitro using three different membrane materials. Human plasma was preliminarily incubated with various inflammatory mediators and filtered in a closed loop circulation model for 240 min. Respective concentrations of 17 different mediators were measured over time to study the removal mechanisms of each membrane, including associated removal time course. The experiment was repeated three times for the assay of tumor necrosis factor (TNF)-α to document the model variability. Means were compared using Mann-Whitney test. Most of the investigated mediators were effectively removed with the different dialysis membranes. Adsorption mechanism was mainly at the origin of the decrease in mediators circulating concentrations and was maximized in the region 10 000-20 000 Da. Especially, the HeprAN membrane showed fast removal capacities of mediators with elevated isoelectric point including complement factors and chemokines or having basic groups located in the protein periphery, plasminogen activator inhibitor (PAI-1), and TNF-α-like. The latter was further significantly removed with HeprAN and polymethylmethacrylate (PMMA) compared to polyethersulfone (PES) material (P < 0.01). We concluded that dialysis using ionic adsorptive membrane could have a beneficial impact for CKD patients with atherosclerosis and would deserve further clinical investigations.

High-volume haemofiltration with a new haemofiltration membrane having enhanced adsorption properties in septic pigs.

BACKGROUND: High-volume haemofiltration (HVHF) has been suggested as an adjuvant treatment of septic shock due to its capacities to remove from blood both pro- and anti-inflammatory mediators involved in the sepsis syndrome. Adsorption properties of some haemofiltration membranes are also interesting with this indication because inflammatory mediators are caught in the membrane itself. The aim of this study was to determine the haemodynamic and immunological effects of a new haemofiltration membrane, which has enhanced adsorption properties due to a special surface treatment, allowing the adsorption of endotoxins. METHODS: We compared this membrane to a standard haemofiltration membrane both in vitro and in 20 sepsis-induced pigs, randomized in two groups. One group was haemofiltered with the treated membrane and the other with the standard haemofiltration membrane during 6-h HVHF sessions. RESULTS: At the end of the experiment, mean +/- SD crystalloids requirements (5937 +/- 1588 versus 7587 +/- 1456 ml, P = 0.026), colloids requirements (1437 +/- 320 versus 1912 +/- 538 ml, P = 0.027), lactic acidosis (pH = 7.20 +/- 0.11 versus 7.10 +/- 0.07, P = 0.026) and pulmonary arterial hypertension (MPAP = 24 +/- 7 versus 34 +/- 8 mmHg, P = 0.008) were less pronounced when HVHF was performed with the treated membrane. In addition, mean +/- SD endotoxins levels were lower in the treated membrane group after 1 hour of HVHF (1.91 +/- 1.19 versus 11.07 +/- 10.64 EU/ml, P = 0.035). Cytokines levels were not different between groups except for IL-1beta, which was slightly lower in the treated membrane group. CONCLUSIONS: The use of a membrane with enhanced adsorption properties during a 6-h HVHF session in septic pigs improves haemodynamics compared to a standard haemofiltration membrane. These results are probably due to an efficient endotoxins and cytokines adsorption. A human study using this membrane is now necessary to confirm these results.