title: Short bacterial DNA fragments: detection in dialysate and induction of cytokines.
abstract: A number of bacterial cytokine-inducing substances (CIS) such as lipopolysaccharides (LPS) and exotoxins have been detected in dialysate and may contribute to inflammation in hemodialysis patients. Short DNA fragments, oligodeoxynucleotides (ODN) of 6 to 20 nucleotides, are able to bind to Toll-like receptors and are stimulatory on immune cells. ODN induce natural killer cell activity and induce IFN-gamma, TNF-alpha, and IL-6 from mononuclear cells. The presence of ODN in dialysate samples and bacterial cultures was investigated. ODN were extracted from fluids by adsorption to reverse-phase columns. ODN were detected in 18 of 20 investigated dialysate samples, in eight of 10 reverse-osmosis water samples, and in all cultures from various bacterial strains. The presence of bacterial DNA in dialysate was confirmed by PCR specific for bacterial tRNA gene sequences. Saline for intravenous use contained 0.02 +/- 0.01 microg/ml DNA, dialysate samples contained 0.28 +/- 0.02 microg/ml, and Pseudomonas cultures contained 1.0 +/- 0.03 microg/ml DNA. ODN from bacterial cultures were only partially removed by ultrafiltration and were able to diffuse through regular high-flux dialyzer membranes. Synthetic cytosine-guanosine dinucleotide-containing ODN were able to induce IL-6 in human mononuclear cells. It is concluded that short bacterial-derived DNA fragments are present in clinically used fluids, e.g., dialysate. These fragments are of sufficient small size to pass through dialyzer membranes. Bacterial DNA fragments may be an overlooked factor contributing to inflammation in hemodialysis patients.
authors.affiliation: Department of Nephrology and Internal Intensive Care Medicine, Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. ralf.schindler@charite.de
authors.forename: Ralf
authors.initials: R
authors.lastname: Schindler
authors.forename: Werner
authors.initials: W
authors.lastname: Beck
authors.forename: Reinhold
authors.initials: R
authors.lastname: Deppisch
authors.forename: Mario
authors.initials: M
authors.lastname: Aussieker
authors.forename: Adelheid
authors.initials: A
authors.lastname: Wilde
authors.forename: Hermann
authors.initials: H
authors.lastname: Göhl
authors.forename: Ulrich
authors.initials: U
authors.lastname: Frei
mesh_terms: D016207:Cytokines / Q000276:immunology*; D004269:DNA, Bacterial / Q000276:immunology* / Q000302:isolation & purification*; D015314:Dialysis Solutions; D004866:Equipment Contamination; D006801:Humans; D066298:In Vitro Techniques; D007676:Kidney Failure, Chronic / Q000276:immunology / Q000628:therapy*; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000382:microbiology*; D008567:Membranes, Artificial; D009838:Oligodeoxyribonucleotides / Q000302:isolation & purification; D011550:Pseudomonas aeruginosa / Q000235:genetics; D006435:Renal Dialysis; D014462:Ultrafiltration
chemical_list: D016207:Cytokines; D004269:DNA, Bacterial; D015314:Dialysis Solutions; D008567:Membranes, Artificial; D009838:Oligodeoxyribonucleotides