Inflammatory Response Variance Based on Quality of Ultrapure Water in Hemodialysis Patients

Abstract

Both the quality of water and biocompatibility of dialyzers are responsible for systemic inflammation in hemodialysis patients. As the biocompatibility of dialyzers has improved, focus for procedural improvements has shifted to water quality. Although ultrapure water reduces the inflammatory response, it is not clear whether different qualities of ultrapure water can further decrease the inflammatory response. This study aims to evaluate the relationship between water quality and the inflammatory response in hemodialysis patients. We enrolled five patients (two men and three women, mean age 44.6 ± 7.36 years) in maintenance hemodialysis (HD) for three sessions a week. Three quality grades of water were applied in successive weeks: Standard water (N0), single-filter ultrapure water (N1), and double-filter ultrapure water (N2). N2 water was created by mixing N1 water with N1 dialysate and passing the mixture through a second filter. Each patient was exposed to different water quality (N0, N1, N2) for a period of 1 week. Monocyte chemoattractant peptide-1 (MCP-1) mRNA expression in peripheral blood mononuclear cells (PBMCs) was determined by real-time PCR. MCP-1 protein in plasma was measured by ELISA. The expression of MCP-1 mRNA in isolated PBMCs after HD was invariant between the N1 and N2 water. The expression of MCP-1 mRNA decreased by 16.1% compared to pre-HD in the N0 system. The expression of MCP-1 mRNA increased by 10.5% in N1 system, and decreased by 12.2% in the N2 system. The water quality did not have a significant impact on MCP-1 protein expression. MCP-1 protein expressions pre- and post-HD were 160.9 ± 13.9 and 153.6 ± 51.6 pg/mL, respectively, when no filter was used (N0). In the case of single-filtered water (N1), the expression levels were 166.6 ± 41.9 and 190.7 ± 88.2 pg/mL pre- and post-HD, respectively. For double-filtered water (N2), the expression levels were 147.8 ± 40.0 and 169.1 ± 52.5 pg/mL pre- and post-HD, respectively. There was no difference in MCP-1 response with respect to the number of water filtration steps in HD patients. Further study with especially ultrapure and sterile water is needed to examine the long-term consequence of water purity on inflammatory reactions, and will require more participants in a longer examination window.