The effects of hemodialysis treatment on the level of DNA strand breaks and oxidative DNA lesions measured by the comet assay

Abstract

Hemodialysis patients have a higher risk for oxidative stress-related complications, such as cardiovascular disease and cancer. The increased level of oxidative stress is due to several factors, e.g., the hemodialysis treatment itself and the uremic state. In the present study, the effects of dialysis treatment on the level of DNA breaks and oxidative DNA lesions in mononuclear cells were measured with the comet assay. Factors possibly affecting DNA damage (reported as % DNA in tail) such as the duration of dialysis, time since last dialysis session, years of dialysis treatment, nutritional status (measured as protein catabolic rate), age, and diabetes were also investigated. The levels of DNA breaks (13.6 ± 4.7 before dialysis) and oxidative DNA lesions (7.9 ± 4.8 before dialysis) were significantly higher in dialysis patients (n = 31) compared to the levels of DNA breaks (5.8 ± 1.1) and oxidative DNA lesions (3.4 ± 1.7) in 10 healthy controls (P < 0.001). A decrease of DNA breaks was observed after dialysis (P = 0.038), and the level of oxidative DNA lesions was higher when the time between two treatment sessions were 68 hours compared to 44 hours (P < 0.001). Older subjects had a higher level of DNA breaks (P = 0.003), a good nutritional status predicted a lower level of DNA breaks (P < 0.001), and the duration of the dialysis session was inversely correlated with oxidative DNA lesions (P = 0.014). Diabetes or years of dialysis treatment did not affect DNA damage. The observations in the present study suggest that accumulation of uremic toxins induce DNA damage. The hemodialysis treatment seems to change the DNA damage.

DNA Damage in End-Stage Renal Disease Patients. Assessment by In Vitro Comet Assay and by Cell-Free DNA Quantification

“…The conversion curve provides a better fitting between %T and AU [55,60] and showed negative values of %T for AU below 26, indicating that %T was zero; above 400 AU, the %T was 84%, in accordance with others [55,60]. Our data is in accordance with other studies reporting that the levels of DNA breaks and oxidative DNA lesions, measured by the comet assay, are higher in dialysis patients then in controls [77].…”

“…We also found that %T was negatively correlated (Spearman's rank correlation) with CRP (r = −0.368; P = 0.021) and ferritin (r = −0.404; P = 0.011), in ESRD patients; no significant correlations were found between DNA lesions and the rhEPO dose used to treat anemia (r = 0.171; P = 0.306), or the time of HD treatment (r = −0.186; P = 0.256). In a cross-sectional study, the oxidative DNA lesions found in dialysis patients were inversely correlated with the duration of the dialysis sessions [77,78]. We did not find significant differences in DNA damage (comet tail length or tail intensity) for diabetics and nondiabetic ESRD patients, as reported by Ersson et al [77]; however, our findings are in accordance with Mamur et al, reporting no difference in comet tail length or tail intensity between diabetic and non-diabetic ESRD patients on HD [78].…”

“…In a cross-sectional study, the oxidative DNA lesions found in dialysis patients were inversely correlated with the duration of the dialysis sessions [77,78]. We did not find significant differences in DNA damage (comet tail length or tail intensity) for diabetics and nondiabetic ESRD patients, as reported by Ersson et al [77]; however, our findings are in accordance with Mamur et al, reporting no difference in comet tail length or tail intensity between diabetic and non-diabetic ESRD patients on HD [78].…”

Ankyrin is the major oxidised protein in erythrocyte membranes from end-stage renal disease patients on chronic haemodialysis and oxidation is decreased by dialysis and vitamin C supplementation

“…Oxidative damage has been attributed to: a) the uremic syndrome itself [14,15], and b) the bio-incompatibility of the haemodialysis membrane [16]. To address this, vitamin E is used for both coating of the haemodialysis membrane [17,18], and as an oral supplementation [19] and has been proven to reduce the recombinant human erythropoietin (rHuEPO) requirement in patients to mitigate anaemia.…”

Reappraisal of putative glyoxalase 1-deficient mouse and dicarbonyl stress on embryonic stem cellsin vitro

“…We propose GLO1 copy number increase in renal failure is due to dicarbonyl stress and/or hypoxia. Decreased GLO1 copy number in one renal failure patient was likely due to DNA damage induced by uremic toxins [65]. There was no association of increased GLO1 copy number with the common SNP C419A.…”