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Influence of anticalcineurinic therapy in plasma homocysteine levels of renal transplant recipients: a prospective study
Influence of Anticalcineurinic Therapy in Plasma Homocysteine Levels of Renal Transplant Recipients: A Prospective Study A.S. Laure´s, E. Gomez, V. Alvarez, E. Coto, J. Baltar, and J. Alvarez-Grande ABSTRACT Hyperhomocysteinemia is an independent factor for cardiovascular disease. Renal function and folate level are important determinants of total plasma homocysteine levels. The influence of anticalcineurin drugs on homocysteine levels is controversial. The aims of the study were: (1) to analyze changes in homocysteine levels after the first year of 73 renal transplants and (2) to determine the influence of immunosuppressive anticalcineurin drug therapy on fasting homocysteine concentrations. We examined homocysteine, serum creatinine, folate, and vitamin B12 concentrations immediately after transplant, at 6 months, and after 12 months from renal transplant. Also, MTHFRC677T polymorphism was investigated. Tacrolimus was administered in 28 patients and cyclosporine in 45. Homocysteine levels decreased from 28.41 ⫾ 13.71 mol/L to 18.59 ⫾ 8.31 mol/L after 6 months and to 17.13 ⫾ 7.06 mol/L after 1 year. No relationship was found between homocysteine and folate levels. When anticalcineurin drugs were considered, the homocysteine levels in patients treated with tacrolimus was lower than that in patients treated with cyclosporine at month 6 after transplant (16 ⫾ 7.4 mol/L vs 20.1 ⫾ 8.5 mol/L, P ⫽ .03) and after 1 year (15 ⫾ 7.6 mol/L vs 18.4 ⫾ 6.4 mol/L, P ⫽ .04). Serum creatinine levels followed the same evolution: they were lower in patients treated with tacrolimus at 6 months (1.35 ⫾ 0.36 mg/dL vs 1.57 ⫾ 0.45 mg/dL, P ⫽ .03) and to a lesser extent at 1 year after renal transplant (1.38 ⫾ 0.35 mg/dL vs 1.54 ⫾ 0.45 mg/dL, P ⫽ .09). The homocysteine value closely related with serum creatinine in both groups. In conclusion, 1 year posttransplant, the homocysteine level was lower among patients treated with tacrolimus, the cohort that also showed the lower serum creatinine concentrations.
H
YPERHOMOCYSTEINEMIA is an independent risk factor for the development of cardiovascular disease.1,2 The fasting homocysteine concentration is directly related to the level of folate, vitamin B12, and B6,3 due to the action of these substances as cofactors in its metabolism. Homocysteine concentration is also inversely related to glomerular filtration,1,3,4 which may explain the high prevalence of hyperhomocysteinemia among patients with renal failure. On the other hand, the mutation C677T in the methylenetetrahydrofolate reductase (MTHFR) gene produces low levels of active folate and possibly predisposing to hyperhomocysteinemia in certain subjects. Patients who are homozygous for this mutation benefit from folic acid treatment.5– 8 An increase in the level of serum homocysteine has been observed among renal transplant recipients,9 even those who have reached a stable level of renal function. Investigations of the relationship between immunosuppressive therapy and hyperhomocys-
teinemia have yielded contradictory results.4,10,11 This prospective study examined the evolution of homocysteine during the first year post-transplant with respect to the influence of anticalcineurin treatment. PATIENTS AND METHODS Serum creatinine, folic acid, B12 vitamin, and fasting homocysteine concentrations were analysed immediately after transplant (first 15 days), after 6 months and after 12 months in 73 consecutive renal transplants recipients (age 50 ⫾ 13 years, 47 men, 25 women). No patients received acid folic supplements. An analysis of From the Nephrology (A.S.L., E.G., J.B., J.A.-G.) and Genetic (V.A., E.C.) Services, Hospital Universitario Central de Asturias, Oviedo, Spain. Address reprint requests to A.S. Laure´s, Nephology Service, Hospital Universitario Central de Asturias, C/ Celestino Villamil s/n, 33006 Oviedo, Spain. E-mail: [email protected]
© 2003 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
0041-1345/03/$–see front matter doi:10.1016/S0041-1345(03)00627-4
Transplantation Proceedings, 35, 1739 –1741 (2003)
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Fig. 1. Panel A: Posttransplant decrease of homocysteine levels (all patients); Panel B: Homocysteine levels in patients treated with tacrolimus (Tac) and cyclosporine (CsA); Panels C-F: Relation between serum creatinine and homocysteine in patients treated with Tac and CyA 6 months after transplant (C and D) and 12 months after transplant (E and F).
ANTICALCINEURINIC AND PLASMA HOMOCYSTEINE MTHFRC677T gene polymorphism was also performed based on a polymerase chain reaction of 16 intron ACE genes. Total plasma homocysteine levels were measured by high-performance liquid chromatography. The immunosuppressive treatment consisted of triple therapy: prednisone, azathioprine, or mycophenolate mofetil and an anticalceneurin drug: 28 patients received tacrolimus (Tacgroup), and 45 cyclosporine (CyA-group). Tacrolimus level was adjusted to 10 to 15 ng/mL during the first month and 5 to 8 ng/mL thereafter. Cyclosporine C0 level was adjusted to 150 to 250 ng/mL for the first month, and 80 to 120 ng/mL thereafter.
RESULTS
As a first step, all 73 patients were analysed. The immediate posttransplant homocysteine level was high (28.41 ⫾ 13.71 mol/L). Six months posttransplant, the level decreased to 18.59 ⫾ 8.31 mol/L and after 12 months to 17.13 ⫾ 7.06 mo/L (P ⬍ .0001, repeated measure of ANOVA) (Fig 1A). Serum creatinine also decreased from 1.75 ⫾ 0.5 mg/dL from day 15 posttransplant to 1.49 ⫾ 0.4 mg/dL after 6 months, and 1.48 ⫾ 30.9 mg/dL after 12 months (P ⫽ .001). A relationship between immediate posttransplant homocysteine and folate concentrations was observed (P ⫽ .03), but this was not present at 6 or 12 months posttransplant (P ⫽ .6 and P ⫽ .8, respectively). In a second step, the parameters were analysed according to the anticalcineurin drugs (Tac or CyA groups). Both groups showed similar distributions/values of gender, age, and time of dialysis, as well as basal concentrations of folic acid and vitamin B12. The immediate posttransplant homocysteine concentrations were similar in the Tac-group (26.9 ⫾ 13.5 mol/L) and CyA-group (29.3 ⫾ 13.9 mol/L) (P ⫽ .47). However, at 6 months posttransplant, homocysteine was lower among the Tac-group (16 ⫾ 7.4 mol/L) than the CyA-group (20.1 ⫾ 8.5 mol/L) (P ⫽ .03). These results were confirmed at 12 months posttransplant (15 ⫾ 7.6 mol/L vs 18.4 ⫾ 6.4 mol/L, P ⫽ .04) (Fig 1B). There were no differences in the folate or vitamin B12 values at 6 and 12 months between the groups. Serum creatinine concentration showed the same evolution as homocysteine: posttransplant serum creatinine concentrations were similar in the Tac-group (1.70 ⫾ 0.6 mg/dL) and CyA-group (1.78 ⫾ 0.5 mg/dL) (P ⫽ .5). But the serum creatinine level was lower in Tac-group than the CyA-group at 6 months posttransplant (1.35 ⫾ 0.36 mg/dL vs 1.57 ⫾ 0.45 mg/dL, P ⫽ .03) and at 12 months posttransplant (1.38 ⫾ 0.35 mg/dL vs 1.54 ⫾ 0.45 P ⫽ .08). The homocysteine was closely related to serum creatinine in both groups (Fig 1C–F). On the other hand, no significant relationship was observed between the polymorphisms of the MTHFR gene and the homocysteinemia concentration.
1741
DISCUSSION
Approximately 80% of dialysis patients show hyperhomocysteinemia. When these patients receive a renal transplant homocysteine level decreases. However, in many cases, some patients do not reach a normal level.4 Several authors have attempted to establish a relationship between hyperhomocysteinemia and immunosuppressive treatment in the same manner as other cardiovascular risk factors. However, the results are not conclusive. In a study by Ducloux et al,11 hyperhomocystinaemia was associated with cardiovascular disease in renal transplant recipients, but CyA did not seem to have a direct effect on homocysteine metabolism. Arnadottir et al12 suggested that cyclosporine interferes with folate-assisted remethylation of homocysteine. FernandezMiranda et al13 did not observe differences in homocysteine concentration among patients treated with cyclosporine versus tacrolimus. In our study, a decrease in homocysteine level was observed over the first year after transplant; the change was greater in patients treated with tacrolimus, a cohort that also showed lower concentrations of serum creatinine. In fact, the renal data may simply explain the difference between homocysteine levels in the two groups. Thus, a relationship between hyperhomocysteinaemia and anticalcineurin drugs cannot be established. Further prospective studies about the contribution of hyperhomocysteinemia to cardiovascular morbidity-mortality of the renal transplant recipients are necessary. REFERENCES 1. Ducloux D, Motte G, Nguyen NU, et al: Nephrol Dial Transplant 17:1674, 2002 2. Bertoni E, Marcucci R, Zanazzi M, et al: J Nephrol 14:36, 2001 3. Friedman AN, Rosenberg IH, Selhub J, et al: Am J Transplant 2:308, 2002 4. Arnadottir M, Hultberg B, Wahlberg J, et al: Kidney Int 54:1380, 1998 5. Fodinger M, Buchmayer H, Heinz G, et al: J Am Soc Nephrol 11:1918, 2000 6. Fodinger M, Wolfl G, Fischer G, et al: Kidney Int 55:1072, 1999 7. Fodinger M, Buchmayer H, Heinz G, et al: Am J Kidney Dis 38:77, 2001 8. Klerb M, Verhoef P, Clarke R, et al: JAMA 288:2023, 2002 9. Ducloux M, Motte G, Challier B, et al: J Am Soc Nephrol 11:134, 2000 10. Machado DJ, Paula FJ, Sabbaga E, et al: Rev Hosp Clin Fac Med 55:161, 2000 11. Ducloux D, Ruedin C, Gibey R, et al: Nephrol Dial Transplant 13:2890, 1998 12. Arnadottir M, Hultberg B, Vladov V, et al: Transplantation 61:509, 1996 13. Fernandez-Miranda C, Gomez P, Diaz-Rubio P, et al: Clin Transplant 14:110, 2000
H
YPERHOMOCYSTEINEMIA is an independent risk factor for the development of cardiovascular disease.1,2 The fasting homocysteine concentration is directly related to the level of folate, vitamin B12, and B6,3 due to the action of these substances as cofactors in its metabolism. Homocysteine concentration is also inversely related to glomerular filtration,1,3,4 which may explain the high prevalence of hyperhomocysteinemia among patients with renal failure. On the other hand, the mutation C677T in the methylenetetrahydrofolate reductase (MTHFR) gene produces low levels of active folate and possibly predisposing to hyperhomocysteinemia in certain subjects. Patients who are homozygous for this mutation benefit from folic acid treatment.5– 8 An increase in the level of serum homocysteine has been observed among renal transplant recipients,9 even those who have reached a stable level of renal function. Investigations of the relationship between immunosuppressive therapy and hyperhomocys-
teinemia have yielded contradictory results.4,10,11 This prospective study examined the evolution of homocysteine during the first year post-transplant with respect to the influence of anticalcineurin treatment. PATIENTS AND METHODS Serum creatinine, folic acid, B12 vitamin, and fasting homocysteine concentrations were analysed immediately after transplant (first 15 days), after 6 months and after 12 months in 73 consecutive renal transplants recipients (age 50 ⫾ 13 years, 47 men, 25 women). No patients received acid folic supplements. An analysis of From the Nephrology (A.S.L., E.G., J.B., J.A.-G.) and Genetic (V.A., E.C.) Services, Hospital Universitario Central de Asturias, Oviedo, Spain. Address reprint requests to A.S. Laure´s, Nephology Service, Hospital Universitario Central de Asturias, C/ Celestino Villamil s/n, 33006 Oviedo, Spain. E-mail: [email protected]
© 2003 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
0041-1345/03/$–see front matter doi:10.1016/S0041-1345(03)00627-4
Transplantation Proceedings, 35, 1739 –1741 (2003)
1739
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LAURE´ S, GOMEZ, ALVAREZ ET AL
Fig. 1. Panel A: Posttransplant decrease of homocysteine levels (all patients); Panel B: Homocysteine levels in patients treated with tacrolimus (Tac) and cyclosporine (CsA); Panels C-F: Relation between serum creatinine and homocysteine in patients treated with Tac and CyA 6 months after transplant (C and D) and 12 months after transplant (E and F).
ANTICALCINEURINIC AND PLASMA HOMOCYSTEINE MTHFRC677T gene polymorphism was also performed based on a polymerase chain reaction of 16 intron ACE genes. Total plasma homocysteine levels were measured by high-performance liquid chromatography. The immunosuppressive treatment consisted of triple therapy: prednisone, azathioprine, or mycophenolate mofetil and an anticalceneurin drug: 28 patients received tacrolimus (Tacgroup), and 45 cyclosporine (CyA-group). Tacrolimus level was adjusted to 10 to 15 ng/mL during the first month and 5 to 8 ng/mL thereafter. Cyclosporine C0 level was adjusted to 150 to 250 ng/mL for the first month, and 80 to 120 ng/mL thereafter.
RESULTS
As a first step, all 73 patients were analysed. The immediate posttransplant homocysteine level was high (28.41 ⫾ 13.71 mol/L). Six months posttransplant, the level decreased to 18.59 ⫾ 8.31 mol/L and after 12 months to 17.13 ⫾ 7.06 mo/L (P ⬍ .0001, repeated measure of ANOVA) (Fig 1A). Serum creatinine also decreased from 1.75 ⫾ 0.5 mg/dL from day 15 posttransplant to 1.49 ⫾ 0.4 mg/dL after 6 months, and 1.48 ⫾ 30.9 mg/dL after 12 months (P ⫽ .001). A relationship between immediate posttransplant homocysteine and folate concentrations was observed (P ⫽ .03), but this was not present at 6 or 12 months posttransplant (P ⫽ .6 and P ⫽ .8, respectively). In a second step, the parameters were analysed according to the anticalcineurin drugs (Tac or CyA groups). Both groups showed similar distributions/values of gender, age, and time of dialysis, as well as basal concentrations of folic acid and vitamin B12. The immediate posttransplant homocysteine concentrations were similar in the Tac-group (26.9 ⫾ 13.5 mol/L) and CyA-group (29.3 ⫾ 13.9 mol/L) (P ⫽ .47). However, at 6 months posttransplant, homocysteine was lower among the Tac-group (16 ⫾ 7.4 mol/L) than the CyA-group (20.1 ⫾ 8.5 mol/L) (P ⫽ .03). These results were confirmed at 12 months posttransplant (15 ⫾ 7.6 mol/L vs 18.4 ⫾ 6.4 mol/L, P ⫽ .04) (Fig 1B). There were no differences in the folate or vitamin B12 values at 6 and 12 months between the groups. Serum creatinine concentration showed the same evolution as homocysteine: posttransplant serum creatinine concentrations were similar in the Tac-group (1.70 ⫾ 0.6 mg/dL) and CyA-group (1.78 ⫾ 0.5 mg/dL) (P ⫽ .5). But the serum creatinine level was lower in Tac-group than the CyA-group at 6 months posttransplant (1.35 ⫾ 0.36 mg/dL vs 1.57 ⫾ 0.45 mg/dL, P ⫽ .03) and at 12 months posttransplant (1.38 ⫾ 0.35 mg/dL vs 1.54 ⫾ 0.45 P ⫽ .08). The homocysteine was closely related to serum creatinine in both groups (Fig 1C–F). On the other hand, no significant relationship was observed between the polymorphisms of the MTHFR gene and the homocysteinemia concentration.
1741
DISCUSSION
Approximately 80% of dialysis patients show hyperhomocysteinemia. When these patients receive a renal transplant homocysteine level decreases. However, in many cases, some patients do not reach a normal level.4 Several authors have attempted to establish a relationship between hyperhomocysteinemia and immunosuppressive treatment in the same manner as other cardiovascular risk factors. However, the results are not conclusive. In a study by Ducloux et al,11 hyperhomocystinaemia was associated with cardiovascular disease in renal transplant recipients, but CyA did not seem to have a direct effect on homocysteine metabolism. Arnadottir et al12 suggested that cyclosporine interferes with folate-assisted remethylation of homocysteine. FernandezMiranda et al13 did not observe differences in homocysteine concentration among patients treated with cyclosporine versus tacrolimus. In our study, a decrease in homocysteine level was observed over the first year after transplant; the change was greater in patients treated with tacrolimus, a cohort that also showed lower concentrations of serum creatinine. In fact, the renal data may simply explain the difference between homocysteine levels in the two groups. Thus, a relationship between hyperhomocysteinaemia and anticalcineurin drugs cannot be established. Further prospective studies about the contribution of hyperhomocysteinemia to cardiovascular morbidity-mortality of the renal transplant recipients are necessary. REFERENCES 1. Ducloux D, Motte G, Nguyen NU, et al: Nephrol Dial Transplant 17:1674, 2002 2. Bertoni E, Marcucci R, Zanazzi M, et al: J Nephrol 14:36, 2001 3. Friedman AN, Rosenberg IH, Selhub J, et al: Am J Transplant 2:308, 2002 4. Arnadottir M, Hultberg B, Wahlberg J, et al: Kidney Int 54:1380, 1998 5. Fodinger M, Buchmayer H, Heinz G, et al: J Am Soc Nephrol 11:1918, 2000 6. Fodinger M, Wolfl G, Fischer G, et al: Kidney Int 55:1072, 1999 7. Fodinger M, Buchmayer H, Heinz G, et al: Am J Kidney Dis 38:77, 2001 8. Klerb M, Verhoef P, Clarke R, et al: JAMA 288:2023, 2002 9. Ducloux M, Motte G, Challier B, et al: J Am Soc Nephrol 11:134, 2000 10. Machado DJ, Paula FJ, Sabbaga E, et al: Rev Hosp Clin Fac Med 55:161, 2000 11. Ducloux D, Ruedin C, Gibey R, et al: Nephrol Dial Transplant 13:2890, 1998 12. Arnadottir M, Hultberg B, Vladov V, et al: Transplantation 61:509, 1996 13. Fernandez-Miranda C, Gomez P, Diaz-Rubio P, et al: Clin Transplant 14:110, 2000