COMMERCIAL DIALYSATE INHIBITS TNF-ALPHA MESSENGER-RNA EXPRESSION AND NF-KAPPA-B DNA-BINDING ACTIVITY IN LPS-STIMULATED MACROPHAGES

Continuous ambulatory peritoneal dialysis is known to interfere with t he normal inflammatory responses of macrophages in the peritoneal cavi ty. Commercial peritoneal dialysis solution (CDS) has been shown to in hibit tumor necrosis factor alpha (TNF alpha)) release from LPS stimul ated peritoneal macrophages. To further dissect the mechanism of this inhibition, we used human blood-derived macrophages or the murine macr ophage cell line, P388D1, that were stimulated with LPS after pretreat ment with CDS, and tested TNF alpha mRNA levels by Northern hybridizat ion or reverse transcriptase polymerase chain reaction. Time course st udies demonstrated that CDS lowered TNF alpha mRNA levels within 15 mi nutes of pretreatment of cells. In addition, the CDS inhibited DNA bin ding activity of NF-kappa B that is probably involved in regulation of LPS-mediated transcriptional activation of the TNF alpha gene. Inhibi tion was dependent on both the low pH and the lactate in the CDS, but was independent of the osmolarity or glucose concentration. The rate o f catabolism of TNF alpha mRNA was not affected by CDS as demonstrated by actinomycin D chase experiments. Thus, impairment of LPS-stimulate d macrophage function by CDS is associated with low TNF alpha mRNA whi ch may be the result of the low activity of NF-kappa B. Since NF-kappa B is involved in transcription regulation of a large number of ''earl y activation'' genes, CDS may interfere with the production of additio nal immunomodulatory proteins that are encoded by genes possessing NF- kappa B site(s) in their promoter region.