Targeting Albumin Binding Function as a Therapy Goal in Liver Failure: Development of a Novel Adsorbent for Albumin Dialysis.

Liver failure results in impaired hepatic detoxification combined with diminished albumin synthesis and is associated with secondary organ failure. The accumulation of liver toxins has shown to saturate albumin binding sites. This was previously demonstrated by an in vitro test for albumin binding capacity (ABiC) that has shown to inversely correlate with the established MELD (Model for End-Stage Liver Disease) score. In this study, we introduced a new adsorbent material for albumin dialysis treatments that improves albumin binding capacity. The new charcoal adsorbent was developed by an evolutionary test schedule. Batch testing of charcoals was performed as steady-state experiments. The charcoal reflecting the highest increase in albumin binding capacity was then introduced to kinetic models: Perfusion tests were designed to evaluate adsorption capacity and kinetics for liver failure marker toxins. A dynamic recirculation model for liver failure was used for upscaling and comparison against conventional MARS adsorbents as the gold standard in an albumin dialysis setting. Batch tests revealed that powdered activated Hepalbin charcoal displayed the highest ABiC score. Hepalbin charcoal also demonstrated higher adsorptive capacity and kinetics for liver failure marker toxins as determined by perfusion tests. These findings translated to tests of upscaled adsorbents in a dynamic model for liver failure: upscaled Hepalbin adsorbent removes bile acids, direct bilirubin and indirect bilirubin significantly better than MARS adsorbents and significantly increases ABiC. The novel adsorbent Hepalbin offers a significant improvement over both MARS adsorbents concerning liver failure marker toxin removal and ABiC improvement.

A New Application for Albumin Dialysis in Extracorporeal Organ Support: Characterization of a Putative Interaction Between Human Albumin and Proinflammatory Cytokines IL-6 and TNFα.

Albumin dialysis in extracorporeal organ support is often performed in the treatment of liver failure as it facilitates the removal of toxic components from the blood. Here, we describe a possible effect of albumin dialysis on proinflammatory cytokine levels in vitro. Initially, albumin samples were incubated with different amounts of cytokines and analyzed by enzyme-linked immunosorbent assay (ELISA). Analysis of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNFα) levels indicated that increased concentrations of albumin reduce the measureable amount of the respective cytokines. This led to the hypothesis that the used proinflammatory cytokines may interact with albumin. Size exclusion chromatography of albumin spiked with cytokines was carried out using high-performance liquid chromatography analysis. The corresponding fractions were evaluated by immunoblotting. We detected albumin and cytokines in the same fractions indicating an interaction of the small-sized cytokines IL-6 and TNFα with the larger-sized albumin. Finally, a two-compartment albumin dialysis in vitro model was used to analyze the effect of albumin on proinflammatory cytokines in the recirculation circuit during 6-h treatment. These in vitro albumin dialysis experiments indicated a significant decrease of IL-6, but not of TNFα, when albumin was added to the dialysate solution. Taken together, we were able to show a putative in vitro interaction of human albumin with the proinflammatory cytokine IL-6, but with less evidence for TNFα, and demonstrated an additional application for albumin dialysis in liver support therapy where IL-6 removal might be indicated.

Reduction of elevated cytokine levels in acute/acute-on-chronic liver failure using super-large pore albumin dialysis treatment: an in vitro study.

The removal of small water soluble toxins and albumin-bound toxins in acute liver failure patients (ALF) or acute-on-chronic liver failure (AocLF) patients has been established using extracorporeal liver support devices (e.g. Molecular Adsorbents Recirculating System; MARS). However, reduction of elevated cytokines in ALF/AocLF using MARS is still not efficient enough to lower patients' serum cytokine levels. New membranes with larger pores or higher cut-offs should be considered in extracorporeal liver support devices based on albumin dialysis in order to address these problems, as the introduction of super-large pore membranes could counterbalance high production rates of cytokines and further improve detoxification in vivo. Using an established in vitro two compartment albumin dialysis model, three novel membranes of different pore sizes were compared with the MARS Flux membrane for cytokine removal and detoxification qualities in vitro. Comparing the membranes, no improvement in the removal of water soluble toxins was found. Albumin-bound toxins were removed more efficiently using novel large (Emic2) to super-large pore sized membranes (S20; HCO Gambro). Clearance of cytokines IL-6 and tumor necrosis factor-α was drastically improved using super-large pore membranes. The Emic2 membrane predominantly removed IL-6. In vitro data suggest that the usage of larger pore sized membranes in albumin dialysis can efficiently reduce elevated cytokine levels and liver failure toxins. Using large to super-large pore membranes might exert effects on patients' serum cytokine levels. Combined with increased detoxification this could lead to higher survival in ALF/AocLF. Promising membranes for clinical evaluation have been identified.