Hemodialysis International 2015; 19:611–618
cells into chondrocyte or osteoblast-like cell, high total cumulative calcium and phosphorus in the body, impaired renal excretion, and high dietary phosphorus and calcium load.1 Advanced age cannot be held responsible per se for this amount of calcification in the absence of CKD. This widespread calcification is, unfortunately, associated with increased morbidity and mortality. Kidney Disease Improving Global Outcomes (KDIGO) guidelines2 recommended that in patients with CKD stages 3–5D, a lateral abdominal radiograph can be used to detect the presence or absence of vascular calcification and an echocardiogram can be used to detect the presence or absence of valvular calcification. This case illustrates an exaggerated example of arterial calcification in a patient with stage 4 CKD. Zeynep ERTURK,1 Seyyid Bilal ACIKGOZ,1 Yalcin SOLAK2 Department of Internal Medicine, School of Medicine, Sakarya University, Sakarya, Turkey; 2 Division of Nephrology, Department of Internal Medicine, Sakarya University Research and Training Hospital, Sakarya, Turkey
1
Figure 1 Plain leg radiographs showing right and left femoral arteries with widespread calcification.
patient complained of left-sided hip pain. X-ray films of the legs and hip showed no fractures but a notable finding of diffuse vascular calcifications. Figure 1 shows easily recognizable bilateral femoral arteries because of widespread calcification of the vessel walls. The patient’s creatinine clearance calculated by Modification of Diet in Renal Disease (MDRD) equation was 19 mL/min/1.73 m2. Vascular calcification is common among patients with CKD. Several risk factors for vascular calcification have been proposed: transformation of vascular smooth muscle
REFERENCES 1 Moe SM, Chen NX. Mechanisms of vascular calcification in chronic kidney disease. J Am Soc Nephrol. 2008; 19:213– 216. Feb, [Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov’t Research Support, U.S. Gov’t, Non-P.H.S. Review]. 2 Moe S, Drueke T, Cunningham J, et al. Definition, evaluation, and classification of renal osteodystrophy: a position statement from Kidney Disease: Improving Global Outcomes (KDIGO). Kidney Int. 2006; 69:1945–1953. Jun, [Consensus Development Conference].
Extracellular superoxide dismutase release by enoxaparin and sparing effect of heparin-grafted hemodialyzer
Correspondence to: J. Borawski, MD, 1st Department of Nephrology and Transplantation with Dialysis Centre, Medical University Hospital, Building B, 14 Zurawia Street, 15-540 Bialystok, Poland. E-mail: [email protected]
To the Editor: In the recent article published in this journal, we reported on the striking increase in plasma myeloperoxidase (MPO) during hemodialysis (HD) procedure anticoagulated with enoxaparin (ENX).1 The MPO increase was minimal
© 2015 International Society for Hemodialysis DOI:10.1111/hdi.12308
614
Letters to the Editor
during HD employing heparin-coated dialyzer membrane and no systemic heparin. The study provided for the first time evidence that ENX releases the prooxidant and proatherosclerotic MPO enzyme from the vascular wall also during HD procedures. This liberation effect seems vasculoprotective. To validate our previous findings and gain further insight into the oxidative stress balance within the arterial wall, we studied plasma activity of extracellular superoxide dismutase (EC-SOD, also known as SOD3). EC-SOD is the major extracellular scavenger of superoxide anion ( O⋅−2 ) and a main regulator of nitric oxide bioactivity. The enzyme plays a crucial role in human health, variety of diseases, and aging.2 EC-SOD (largely its Cu/Zn isoform) is mainly produced by vascular smooth muscles and stored in large amounts within the arterial wall. As a glycoprotein, it has affinity to heparan sulfate proteoglycans and (like MPO) avidly binds to endothelial glycocalyx.2 EC-SOD is known for almost 30 years to be effectively released from its arterial reservoir by exogenous heparin.2,3 Regarding HD therapy, overdialytic increases in EC-SOD were reported and ascribed to enigmatically enhanced antioxidant capacity of leukocytes or ongoing intradialytic vascular injury.4,5 The two studies did not account for the plausible EC-SOD boosting effect of highdose heparin injected for HD anticoagulation.6,7 The present pilot study is the first to investigate the issue of EC-SOD/heparin connections during HD procedure. The study protocol, enrollment criteria, and population have been described in detail elsewhere.1 In brief, 19 patients on maintenance HD were studied during routine ENX-anticoagulated procedure (median i.v. dose 0.54 mg/kg, range 0.29–0.73 mg/kg) with polysulfone dialyzers. The subjects were retested after a week during the session employing surface-matched dialyzers with the anti-thrombogenic unfractionated heparin-grafted HeprAN hydrogel membrane (Evodial, Gambro Lundia AB, Lund, Sweden) derived from polyacrylonitrile AN69ST membrane and without systemic ENX. Blood was sampled before onset of a midweek morning HD (T0, before heparinization in ENX-HD), and again after 10 (T10) and 120 minutes (T120) of the procedure, and then deep frozen. Plasma EC-SOD was quantified with the DetectX® SOD colorimetric activity kit cat. no. KO28-H1 (Arbor Assays, Ann Arbor, MI, USA). This novel assay measures all types of SOD activity, including Cu/Zn and the primarily intracellular Mn, and FeSOD types. According to the manufacturer, EC-SOD in plasma samples from healthy humans ranged from 2.24 to 3.56 U/mL with an average of 2.89 U/mL. During ENX-anticoagulated HD procedures plasma EC-SOD activity significantly changed (one-way analysis of
Hemodialysis International 2015; 19:611–618
variance [ANOVA] P = 0.012, F = 4.77). It was T0 0.74 ± 0.24 U/mL, T10 1.06 ± 0.40 U/mL, and T120 0.91 ± 0.30 U/mL. At T10 the EC-SOD activity was higher by a mean of 43% than that at T0 (post-hoc Tukey’s honest significance test P = 0.009). The percentage increment at T10 vs. T0 was not associated with the ENX dosage (Pearson’s r = 0.088, P = 0.721). EC-SOD activity remained stable during heparin-free HD sessions with the Evodial dialyzer: T0 0.69 ± 0.24 U/mL, T10 0.68 ± 0.17 U/mL, T120 0.64 ± 0.16 U/mL (one-way ANOVA P = 0.317, F = 1.17). The predialysis (T0) EC-SOD activities were equal for the two procedures (Student’s t test P = 0.894). Case profiles of overdialytic EC-SOD are shown in Figure 1. Vascular EC-SOD deficits (both acquired and inborn) are strongly linked to conditions/diseases such as endothelial dysfunction, atherosclerosis, hypertension, and their lethal cardiovascular sequels.2,6–10 It was documented that EC-SOD released into circulation by heparin (which mirrors the arterial stores of the bioactive enzyme) was significantly lower in patients with advanced atherosclerosis, and diminished heparin-released EC-SOD contributed to coronary artery calcium score.6 Interestingly, human EC-SOD gene transfer and replenishment has been successful in various disease models, and shown to protect against vascular dysfunction and aging, reduce vascular resistance and arterial pressure, improve endothelial dysfunction in hypertension and heart failure, etc.7 On the other hand, EC-SOD depletion due to missense mutation (substitution at the heparin-binding domain) of its gene (EC-SOD–R213G) increases plasma enzyme concentration 10-fold due to its accelerated release from the arterial wall.7,8 The Copenhagen City Heart Study proved that people heterozygous for EC-SOD–R213G had a dramatically (by 70%) increased risk of ischemic heart disease events during 23 years of follow-up.8 Similar consequences of this genetic defect on the incidence of heart and cerebrovascular disease were observed in maintenance HD patients.9 Low SOD activity in HD patients (reflecting extensive endothelial damage) also predicted their allcause and cardiovascular mortality.10 It is plausible that the repetitive and long-time administration of heparin for HD procedures depletes arterial stores of EC-SOD and has negative consequences. Use of Evodial dialyzers may protect the arteries against the superoxide-induced damage. Further research is warranted.
ACKNOWLEDGMENTS The study was funded by the Medical University of Bialystok, Poland (grant No. 113-54755L). The authors
615
Letters to the Editor
Figure 1 Case profiles of plasma extracellular superoxide dismutase (EC-SOD) activity during hemodialysis with intravascular enoxaparin and heparin-free procedure with Evodial dialyzer.
were not supported by the manufacturer of Evodial dialyzers.
DISCLOSURES None declared. For funding information, see “The Global Forum on Home Hemodialysis: Sponsorship and Disclosure Statements.” Jacek BORAWSKI,1 Joanna GOZDZIKIEWICZ-LAPINSKA,2 Beata NAUMNIK1 1 1st Department of Nephrology and Transplantation with Dialysis Centre, 2 2nd Department of Nephrology with Hypertension and Dialysis Units, Medical University, Bialystok, Poland
REFERENCES 1 Gozdzikiewicz J, Borawski J, Koc-Zorawska E, Mysliwiec M. Effects of enoxaparin on myeloperoxidase release during hemodialysis. Hemodial Int. 2014; 18:819–824. 2 Fukai T, Ushio-Fukai M. Superoxide dismutases: Role in redox signaling, vascular function, and diseases. Antioxid Redox Signal. 2011; 15:1583–1606. 3 Karlsson K, Marklund SL. Heparin-induced release of extracellular superoxide dismutase to human blood plasma. Biochem J. 1987; 242:55–59.
616
4 Shimomura H, Maehata E, Takamiya T, Adachi T, Komoda T. Blood extracellular superoxide dismutase levels in hemodialysis patients pre- and posthemodialysis and its associations with lipoprotein lipase mass and free fatty acid. Clin Chim Acta. 2003; 328:113– 119. 5 Akiyama S, Inagaki M, Tsuji M, et al. mRNA study on Cu/Zn superoxide dismutase induction by hemodialysis treatment. Nephron Clin Pract. 2005; 99:107–114. 6 Tasaki H, Yamashita K, Tsutsui M, et al. Heparin-released extracellular superoxide dismutase is reduced in patients with coronary artery atherosclerosis. Atherosclerosis. 2006; 187:131–138. 7 Qin Z, Reszka KJ, Fukai T, Weintraub NL. Extracellular superoxide dismutase (ecSOD) in vascular biology: An update on exogenous gene transfer and endogenous regulators of ecSOD. Transl Res. 2008; 151:68–78. 8 Juul K, Tybjaerg-Hansen A, Marklund S, et al. Genetically reduced antioxidative protection and increased ischemic heart disease risk: The Copenhagen City Heart Study. Circulation. 2004; 109:59–65. 9 Yamada H, Yamada Y, Adachi T, et al. Protective role of extracellular superoxide dismutase in hemodialysis patients. Nephron. 2000; 84:218–223. 10 Antunovic T, Stefanovic A, Ratkovic M, et al. High uric acid and low superoxide dismutase as possible predictors of all-cause and cardiovascular mortality in hemodialysis patients. Int Urol Nephrol. 2013; 45:1111–1119.
Hemodialysis International 2015; 19:611–618
cells into chondrocyte or osteoblast-like cell, high total cumulative calcium and phosphorus in the body, impaired renal excretion, and high dietary phosphorus and calcium load.1 Advanced age cannot be held responsible per se for this amount of calcification in the absence of CKD. This widespread calcification is, unfortunately, associated with increased morbidity and mortality. Kidney Disease Improving Global Outcomes (KDIGO) guidelines2 recommended that in patients with CKD stages 3–5D, a lateral abdominal radiograph can be used to detect the presence or absence of vascular calcification and an echocardiogram can be used to detect the presence or absence of valvular calcification. This case illustrates an exaggerated example of arterial calcification in a patient with stage 4 CKD. Zeynep ERTURK,1 Seyyid Bilal ACIKGOZ,1 Yalcin SOLAK2 Department of Internal Medicine, School of Medicine, Sakarya University, Sakarya, Turkey; 2 Division of Nephrology, Department of Internal Medicine, Sakarya University Research and Training Hospital, Sakarya, Turkey
1
Figure 1 Plain leg radiographs showing right and left femoral arteries with widespread calcification.
patient complained of left-sided hip pain. X-ray films of the legs and hip showed no fractures but a notable finding of diffuse vascular calcifications. Figure 1 shows easily recognizable bilateral femoral arteries because of widespread calcification of the vessel walls. The patient’s creatinine clearance calculated by Modification of Diet in Renal Disease (MDRD) equation was 19 mL/min/1.73 m2. Vascular calcification is common among patients with CKD. Several risk factors for vascular calcification have been proposed: transformation of vascular smooth muscle
REFERENCES 1 Moe SM, Chen NX. Mechanisms of vascular calcification in chronic kidney disease. J Am Soc Nephrol. 2008; 19:213– 216. Feb, [Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov’t Research Support, U.S. Gov’t, Non-P.H.S. Review]. 2 Moe S, Drueke T, Cunningham J, et al. Definition, evaluation, and classification of renal osteodystrophy: a position statement from Kidney Disease: Improving Global Outcomes (KDIGO). Kidney Int. 2006; 69:1945–1953. Jun, [Consensus Development Conference].
Extracellular superoxide dismutase release by enoxaparin and sparing effect of heparin-grafted hemodialyzer
Correspondence to: J. Borawski, MD, 1st Department of Nephrology and Transplantation with Dialysis Centre, Medical University Hospital, Building B, 14 Zurawia Street, 15-540 Bialystok, Poland. E-mail: [email protected]
To the Editor: In the recent article published in this journal, we reported on the striking increase in plasma myeloperoxidase (MPO) during hemodialysis (HD) procedure anticoagulated with enoxaparin (ENX).1 The MPO increase was minimal
© 2015 International Society for Hemodialysis DOI:10.1111/hdi.12308
614
Letters to the Editor
during HD employing heparin-coated dialyzer membrane and no systemic heparin. The study provided for the first time evidence that ENX releases the prooxidant and proatherosclerotic MPO enzyme from the vascular wall also during HD procedures. This liberation effect seems vasculoprotective. To validate our previous findings and gain further insight into the oxidative stress balance within the arterial wall, we studied plasma activity of extracellular superoxide dismutase (EC-SOD, also known as SOD3). EC-SOD is the major extracellular scavenger of superoxide anion ( O⋅−2 ) and a main regulator of nitric oxide bioactivity. The enzyme plays a crucial role in human health, variety of diseases, and aging.2 EC-SOD (largely its Cu/Zn isoform) is mainly produced by vascular smooth muscles and stored in large amounts within the arterial wall. As a glycoprotein, it has affinity to heparan sulfate proteoglycans and (like MPO) avidly binds to endothelial glycocalyx.2 EC-SOD is known for almost 30 years to be effectively released from its arterial reservoir by exogenous heparin.2,3 Regarding HD therapy, overdialytic increases in EC-SOD were reported and ascribed to enigmatically enhanced antioxidant capacity of leukocytes or ongoing intradialytic vascular injury.4,5 The two studies did not account for the plausible EC-SOD boosting effect of highdose heparin injected for HD anticoagulation.6,7 The present pilot study is the first to investigate the issue of EC-SOD/heparin connections during HD procedure. The study protocol, enrollment criteria, and population have been described in detail elsewhere.1 In brief, 19 patients on maintenance HD were studied during routine ENX-anticoagulated procedure (median i.v. dose 0.54 mg/kg, range 0.29–0.73 mg/kg) with polysulfone dialyzers. The subjects were retested after a week during the session employing surface-matched dialyzers with the anti-thrombogenic unfractionated heparin-grafted HeprAN hydrogel membrane (Evodial, Gambro Lundia AB, Lund, Sweden) derived from polyacrylonitrile AN69ST membrane and without systemic ENX. Blood was sampled before onset of a midweek morning HD (T0, before heparinization in ENX-HD), and again after 10 (T10) and 120 minutes (T120) of the procedure, and then deep frozen. Plasma EC-SOD was quantified with the DetectX® SOD colorimetric activity kit cat. no. KO28-H1 (Arbor Assays, Ann Arbor, MI, USA). This novel assay measures all types of SOD activity, including Cu/Zn and the primarily intracellular Mn, and FeSOD types. According to the manufacturer, EC-SOD in plasma samples from healthy humans ranged from 2.24 to 3.56 U/mL with an average of 2.89 U/mL. During ENX-anticoagulated HD procedures plasma EC-SOD activity significantly changed (one-way analysis of
Hemodialysis International 2015; 19:611–618
variance [ANOVA] P = 0.012, F = 4.77). It was T0 0.74 ± 0.24 U/mL, T10 1.06 ± 0.40 U/mL, and T120 0.91 ± 0.30 U/mL. At T10 the EC-SOD activity was higher by a mean of 43% than that at T0 (post-hoc Tukey’s honest significance test P = 0.009). The percentage increment at T10 vs. T0 was not associated with the ENX dosage (Pearson’s r = 0.088, P = 0.721). EC-SOD activity remained stable during heparin-free HD sessions with the Evodial dialyzer: T0 0.69 ± 0.24 U/mL, T10 0.68 ± 0.17 U/mL, T120 0.64 ± 0.16 U/mL (one-way ANOVA P = 0.317, F = 1.17). The predialysis (T0) EC-SOD activities were equal for the two procedures (Student’s t test P = 0.894). Case profiles of overdialytic EC-SOD are shown in Figure 1. Vascular EC-SOD deficits (both acquired and inborn) are strongly linked to conditions/diseases such as endothelial dysfunction, atherosclerosis, hypertension, and their lethal cardiovascular sequels.2,6–10 It was documented that EC-SOD released into circulation by heparin (which mirrors the arterial stores of the bioactive enzyme) was significantly lower in patients with advanced atherosclerosis, and diminished heparin-released EC-SOD contributed to coronary artery calcium score.6 Interestingly, human EC-SOD gene transfer and replenishment has been successful in various disease models, and shown to protect against vascular dysfunction and aging, reduce vascular resistance and arterial pressure, improve endothelial dysfunction in hypertension and heart failure, etc.7 On the other hand, EC-SOD depletion due to missense mutation (substitution at the heparin-binding domain) of its gene (EC-SOD–R213G) increases plasma enzyme concentration 10-fold due to its accelerated release from the arterial wall.7,8 The Copenhagen City Heart Study proved that people heterozygous for EC-SOD–R213G had a dramatically (by 70%) increased risk of ischemic heart disease events during 23 years of follow-up.8 Similar consequences of this genetic defect on the incidence of heart and cerebrovascular disease were observed in maintenance HD patients.9 Low SOD activity in HD patients (reflecting extensive endothelial damage) also predicted their allcause and cardiovascular mortality.10 It is plausible that the repetitive and long-time administration of heparin for HD procedures depletes arterial stores of EC-SOD and has negative consequences. Use of Evodial dialyzers may protect the arteries against the superoxide-induced damage. Further research is warranted.
ACKNOWLEDGMENTS The study was funded by the Medical University of Bialystok, Poland (grant No. 113-54755L). The authors
615
Letters to the Editor
Figure 1 Case profiles of plasma extracellular superoxide dismutase (EC-SOD) activity during hemodialysis with intravascular enoxaparin and heparin-free procedure with Evodial dialyzer.
were not supported by the manufacturer of Evodial dialyzers.
DISCLOSURES None declared. For funding information, see “The Global Forum on Home Hemodialysis: Sponsorship and Disclosure Statements.” Jacek BORAWSKI,1 Joanna GOZDZIKIEWICZ-LAPINSKA,2 Beata NAUMNIK1 1 1st Department of Nephrology and Transplantation with Dialysis Centre, 2 2nd Department of Nephrology with Hypertension and Dialysis Units, Medical University, Bialystok, Poland
REFERENCES 1 Gozdzikiewicz J, Borawski J, Koc-Zorawska E, Mysliwiec M. Effects of enoxaparin on myeloperoxidase release during hemodialysis. Hemodial Int. 2014; 18:819–824. 2 Fukai T, Ushio-Fukai M. Superoxide dismutases: Role in redox signaling, vascular function, and diseases. Antioxid Redox Signal. 2011; 15:1583–1606. 3 Karlsson K, Marklund SL. Heparin-induced release of extracellular superoxide dismutase to human blood plasma. Biochem J. 1987; 242:55–59.
616
4 Shimomura H, Maehata E, Takamiya T, Adachi T, Komoda T. Blood extracellular superoxide dismutase levels in hemodialysis patients pre- and posthemodialysis and its associations with lipoprotein lipase mass and free fatty acid. Clin Chim Acta. 2003; 328:113– 119. 5 Akiyama S, Inagaki M, Tsuji M, et al. mRNA study on Cu/Zn superoxide dismutase induction by hemodialysis treatment. Nephron Clin Pract. 2005; 99:107–114. 6 Tasaki H, Yamashita K, Tsutsui M, et al. Heparin-released extracellular superoxide dismutase is reduced in patients with coronary artery atherosclerosis. Atherosclerosis. 2006; 187:131–138. 7 Qin Z, Reszka KJ, Fukai T, Weintraub NL. Extracellular superoxide dismutase (ecSOD) in vascular biology: An update on exogenous gene transfer and endogenous regulators of ecSOD. Transl Res. 2008; 151:68–78. 8 Juul K, Tybjaerg-Hansen A, Marklund S, et al. Genetically reduced antioxidative protection and increased ischemic heart disease risk: The Copenhagen City Heart Study. Circulation. 2004; 109:59–65. 9 Yamada H, Yamada Y, Adachi T, et al. Protective role of extracellular superoxide dismutase in hemodialysis patients. Nephron. 2000; 84:218–223. 10 Antunovic T, Stefanovic A, Ratkovic M, et al. High uric acid and low superoxide dismutase as possible predictors of all-cause and cardiovascular mortality in hemodialysis patients. Int Urol Nephrol. 2013; 45:1111–1119.
Hemodialysis International 2015; 19:611–618
