Dialysate cell-free mitochondrial DNA fragments as a marker of intraperitoneal inflammation and peritoneal solute transport rate in peritoneal dialysis

Background Mitochondrial DNA (mtDNA) released into extracellular subsequent to cell injury and death can promote inflammation in patients and animal models. However, the effects of peritoneal dialysate cell-free mtDNA on intraperitoneal inflammation and peritoneal solute transport rate (PSTR) in peritoneal dialysis (PD) patients remain unclear. Methods We select the incident patients who began PD therapy between January 1, 2009, and December 30, 2010. Peritoneal dialysate was collected at the time of peritoneal equilibration test. The cell-free mtDNA, IL-6, IL-17A, TNF-α and IFN-γ were measured. All patients were followed till December 2017. The results were compared with PSTR and patient survival. Results One hundred and eighty-nine patients were included in the study. The average age was 47.1 ± 13.5 years, 55.6% of the patients were males. The average PSTR was 0.66 ± 0.12, the median dialysate mtDNA levels were 4325 copies/ul. The median concentrations of IL-6, IL-17A, TNF-α and IFN-γ were 25.9, 10.8, 25.8 and 17.9 pg/ml, respectively. We found that dialysate mtDNA was significantly correlated with PSTR ( r = 0.461, P < 0.001), IL-6 ( r = 0.568, P < 0.001), TNF-α ( r = 0.454, P < 0.001) and IFN-γ ( r = 0.203, P = 0.005). After adjustment for multiple covariates, dialysate mtDNA levels were independently correlated with IL-6 and PSTR. Dialysate mtDNA levels were not associated with patient survival. Conclusions We found that dialysate mtDNA levels correlated with the degree of intraperitoneal inflammatory status in PD patients. Peritoneal effluent mtDNA was an independent determinant of PSTR but did not affect patient survival.