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In-vitro biocompatibility of alternative CAPD fluids; comparison of bicarbonate-buffered and glucose-polymer-based
1Department of Nephrology, Universitätsklinikum Rudolf Virchow, Berlin-Charlottenburg, Germany.
Abstract:
Evidence is accumulating that conventional dialysis fluids for CAPD are incompatible with peritoneal host defence. We therefore investigated the effect of alternative CAPD fluids on mononuclear leukocyte (PBMC) viability and cytokine production in vitro. Fluids tested were bicarbonate-buffered solutions containing 1.5% or 4.25% glucose, 7.5% glucose polymer dialysis fluid (GPDF), and conventional 1.5% glucose fluid (G1.5%). PBMC were stimulated (2 h, 37 degrees C) in the different test fluids with a clinical isolate of Staphylococcus epidermidis or Escherichia coli lipopolysaccharide. The cytokines TNF alpha and IL-6 in PBMC supernatants were measured by specific enzyme immunoassays. Induction of cytokine messenger RNA was evaluated by reverse transcription-polymerase chain reaction. Conventional G1.5% (pH 5.5) inhibited cytokine release from activated PBMC by > 95%, whereas cell responses in low-glucose bicarbonate fluid were not significantly reduced. In contrast, high-glucose bicarbonate fluid exerted > 80% inhibition despite its neutral pH. GPDF was inhibitory at its initial low pH, whereas cytokine release was restored following pH neutralization. Cytokine mRNA expression was suppressed by conventional G1.5% fluid and by high-glucose bicarbonate fluid. These data indicate that pH neutralization leads to a substantial improvement of dialysis fluid biocompatibility; however, hyperosmolality and/or high glucose content inhibit cell responsiveness even at normal pH. Replacement of glucose by glucose polymer might prove beneficial provided that the initial low pH is neutralized.
Insights
Conventional dialysis fluids harm peritoneal host defense. Alternative bicarbonate-buffered solutions improve mononuclear leukocyte viability and cytokine production, suggesting enhanced biocompatibility for CAPD patients.
Area of Science:
- Immunology
- Nephrology
- Biocompatibility
Background:
- Conventional dialysis fluids for continuous ambulatory peritoneal dialysis (CAPD) may impair peritoneal host defense mechanisms.
- Investigating alternative dialysis fluid compositions is crucial for improving patient outcomes.
Purpose of the Study:
- To evaluate the in vitro effects of alternative CAPD fluids on mononuclear leukocyte (PBMC) viability and cytokine production.
- To compare the biocompatibility of bicarbonate-buffered solutions with varying glucose concentrations and glucose polymer dialysis fluid (GPDF) against conventional fluid.
Main Methods:
- PBMCs were stimulated with Staphylococcus epidermidis or Escherichia coli lipopolysaccharide in different dialysis fluids.
- Cytokine (TNF-alpha, IL-6) levels in supernatants were measured using enzyme immunoassays.
- Cytokine mRNA expression was analyzed via reverse transcription-polymerase chain reaction.
Main Results:
- Conventional 1.5% glucose fluid (G1.5%, pH 5.5) significantly inhibited cytokine release (>95%).
- Bicarbonate-buffered fluids showed improved cell responses, with high-glucose fluid causing >80% inhibition despite neutral pH.
- GPDF was inhibitory at low pH but restored cytokine release after neutralization; mRNA expression was suppressed by G1.5% and high-glucose bicarbonate fluid.
Conclusions:
- pH neutralization significantly enhances dialysis fluid biocompatibility.
- Hyperosmolality and high glucose content inhibit cellular responsiveness even at neutral pH.
- Glucose polymer dialysis fluid may be beneficial for CAPD if initial low pH is addressed.
