Nucleosome levels and toll-like receptor expression during high cut-off haemofiltration: a pilot assessment.

OBJECTIVES: To measure plasma nucleosome levels and expression of toll-like receptors (TLRs) in a pilot cohort of patients with severe acute kidney injury (AKI) within a randomised controlled trial of continuous venovenous haemofiltration with high cut-off filters (CVVH-HCO) v standard filters (CVVH-std).

METHODS: We measured plasma nucleosome levels using the Cell Death Detection ELISA PLUS (10X) assay kit. We analysed plasma levels for correlation with disease severity and compared the effects of CVVH-HCO and CVVH-std on plasma nucleosome levels over the first 72 hours. We studied cell surface TLR expression on CD14-positive monocytes in a subcohort of CVVH-HCO patients.

RESULTS: We did not detect nucleosomes in normal human plasma, but found elevated nucleosome levels in patients with severe AKI. Nucleosome levels at randomisation correlated weakly with Acute Physiology and Chronic Health Evaluation III scores (Pearson ρ=0.475, P=0.016). Treatment with CVVH-HCO or CVVH-std had no effect on nucleosome levels over 72 hours. The mean fluorescence intensity (MFI) ratios of TLR2 and TLR4 expression were elevated throughout the 72-hour period (range for TLR2, 0.97-3.98; range for TLR4, 0.91-10.18) and did not appear to decrease as a result of treatment with CVVH-HCO.

CONCLUSIONS: Nucleosome concentration was elevated in the plasma of patients with severe AKI and mildly correlated with disease severity, but was not affected by treatment with CVVH-HCO or CVVH-std. Similarly, levels of TLR2 and TLR4 expression did not decrease over time during CVVHCrit HCO treatment.