8-Hydroxy-2′-deoxyguanosine and malondialdehyde in plasma and their association with disease severity in 20 cats with chronic kidney disease

Abstract

Objectives Oxidative stress is associated with the development and progression of chronic kidney disease (CKD) in humans. The aim of this study was to evaluate the concentrations of oxidative stress markers, 8-hydroxy-2′-deoxyguanosine (8-OHdG) and malondialdehyde (MDA), in the plasma and urine of cats with different stages of CKD. Methods Plasma and urine samples were collected from cats with CKD that were referred to the Veterinary Medical Center of the University of Tokyo between April 2019 and October 2022. Plasma and urine samples were collected from healthy cats (n = 6 at most), cats with stage 2 CKD (n = 8) and stage 3–4 CKD (n = 12), and cats with idiopathic cystitis (disease control, n = 5). Plasma and urine concentrations of 8-OHdG and MDA were measured using ELISA and thiobarbituric acid reactive substances assay kits, respectively. Results The median plasma 8-OHdG concentrations were 0.156 ng/ml (<0.125–0.210 ng/ml) in the healthy group, <0.125 ng/ml (range <0.125 ng/ml) in the idiopathic cystitis group, 0.246 ng/ml (range 0.170–0.403 ng/ml) in cats with stage 2 CKD and 0.433 ng/ml (range 0.209–1.052 ng/ml) in cats with stage 3–4 CKD. Concentrations in stage 3–4 CKD were significantly higher than those in the healthy and disease control groups. Plasma MDA concentrations were low in the healthy and disease control groups and significantly higher in cats with stage 3–4 CKD. In every cat with CKD, plasma 8-OHdG and MDA concentrations were positively correlated with plasma creatinine concentrations (8-OHdG, rs = 0.68; MDA, rs = 0.67). Urinary 8-OHdG/urinary creatinine (u-CRE) and urinary MDA/u-CRE levels did not differ significantly between the groups; however, it was difficult to evaluate them because of the small sample size. Conclusions and relevance This report shows that plasma 8-OHdG and MDA concentrations increase with the severity of feline CKD. These markers may be useful for assessing oxidative stress in cats with CKD.

Supplementation of vitamin E as an addition to a commercial renal diet does not prolong survival of cats with chronic kidney disease

“…Before supplementation, no statistically significant difference in the degree of lipid peroxidation (MDA) and protein carbonylation (PC) was observed between cats with CKD and the group of healthy. In contrast to our results, increased levels of markers of lipid peroxidation (MDA; plasma and/or urinary F2-isoprostanes) [ 18 , 22 , 23 , 26 ], and oxidative damage to proteins (advanced oxidation protein products) [ 18 ] and oxidative damage to DNA (8-OHdG) [ 26 ] have been reported in CKD cats compared with healthy cats. Similar results were obtained in human CKD patients [ 56 , 57 ].…”

“…Similarly, statistically significantly increased level of the lipid peroxidation markers, urinary [ 22 , 23 ] and plasma [ 23 ] F2-isoprostanes, were found in early CKD. In another study, no significant difference in plasma MDA concentration between cats in IRIS stage 2 and IRIS stage 3–4 was reported [ 26 ]. Our results suggest that there may be an induction of antioxidant defence mechanisms that prevent lipid peroxidation in later stages of CKD, as suggested by previously published studies [ 19 , 20 , 22 ].…”

“…In another study, no differences in oxidative stress parameters in CKD cats compared to healthy cats were found [ 21 ]. In contrast, the authors of a recent study reported that plasma concentrations of malondialdehyde (MDA), a known lipid peroxidation biomarker, and 8-hydroxy-2 ’ -deoxy-guanosine (8-OHdG), a biomarker of oxidative DNA damage, increase with the severity of feline CKD [ 26 ].…”