Influence of mycophenolic acid and tacrolimus on homocysteine metabolism

BACKGROUND: The effect of mycophenolate mofetil (MMF) on homocysteine (Hcy) metabolism is unknown. METHODS: This in vitro study examined whether mycophenolic acid or tacrolimus influences the formation of Hcy as determined by measuring the total Hcy (tHcy) concentrations in supernatants of human renal proximal tubule epithelial cells. Cells were incubated with and without vitamins (folate, vitamin B6 and B12) in the presence of low or high methionine concentrations at different mycophenolic acid (0, or 5, or 20 microg/mL) or tacrolimus (0, or 10, or 25 ng/mL) concentrations for 24, 48 or 72 hours. The concentration of tHcy in culture supernatants was measured by a fluorescence polarization immunoassay. The effect of MMF on tHcy plasma levels was also examined in 454 kidney graft recipients. RESULTS: Comparisons of tHcy levels in culture supernatants over time by four way ANOVA showed that methionine concentration (P < 0.00001), time (P < 0.00001), vitamins (P = 0.002728), and mycophenolic acid concentration (P = 0.000095) were all significant predictors of tHcy concentrations. This was due to significantly lower tHcy levels with using mycophenolic acid at a high concentration versus control at the 48- and 72-hour time points. By contrast, tacrolimus showed no effect in vitro. Among the kidney graft recipients, male patients on MMF therapy showed lower plasma tHcy concentrations as compared to those on azathioprine (P = 0.03). CONCLUSION: Our study suggests a tHcy lowering effect of MMF in male transplant recipients, which improves the cardiovascular disease risk profile, whereas tacrolimus showed no effect.     

Homocysteine, nutritional status and insulin in renal transplant recipients.

BACKGROUND: Hyperhomocysteinemia is an independent risk factor for the development of cardiovascular conditions in chronic stable renal-transplant recipients (RTR). Major determinants of plasma total homocysteine (tHcy) in RTR are renal function and folate levels. The data dealing with the possible regulation of the tHcy metabolism by insulin and nutritional status is conflicting in non-transplant populations. METHODS: We examined the relationship between tHcy, insulin and nutritional status in 103 chronic, stable RTR. Demographic, clinical, and biochemical parameters were assessed for each patient. RESULTS: Mean tHcy was 19.7+/-9.2 micro mol/l (range 8.6-53). The tHcy was strongly related to creatinine clearance (r=0.55, P<0.0001). Fasting tHcy levels were negatively related to folate concentrations (r=-0.32, P=0.01). There was a positive relationship between tHcy and LDL-cholesterol (r=0.34, P=0.03) and a significant negative correlation between tHcy and insulin (r=-0.38, P=0.01). Fasting tHcy concentrations were significantly higher in the lower quartile of insulin concentration than in the upper quartile (27.7+/-12.7 vs 15.9+/-9.5, P=0.01). In multivariate analysis, tHcy was associated with serum creatinine (P=0.001), insulin (P=0.02) and folate concentration (P=0.03). Patients with the highest IGF-1 concentration had lower tHcy than patients with the lowest IGF-1 concentration (16.8+/-5.7 vs 23.3+/-11 micro mol/l, P=0.01). CONCLUSION: We observed an inverse relationship between insulin and tHcy in chronic, stable RTR.     

Hyperhomocysteinemia in stable pediatric, adolescents, and young adult renal transplant recipients.

BACKGROUND: High total plasma homocysteine (tHcy) levels are accompanied by an increased risk for premature development of atherosclerosis and atherothrombosis. Adult renal transplant recipients have elevated tHcy levels. Corresponding data in pediatric, adolescent, and young adult renal transplant recipients are scarce. We investigated whether tHcy levels were elevated in stable renal transplant recipients who received kidney grafts before age 18. METHODS: This cross-sectional study was conducted during routine posttransplantation follow-up. Fasting tHcy levels, serum creatinine, and lipoprotein profile were measured in 38 clinically stable renal transplant recipients with different degrees of renal function. No patient was receiving B vitamin or folic acid supplementation. Estimated glomerular filtration rate (GFR) was assessed according to Schwartz's formula. All patients followed a triple-drug immunosuppressive regimen, with the exception of three patients (deflazacort and azathioprine). Forty-one apparently healthy subjects constituted the control group. tHcy levels were determined by fluorescence polarization immunoassay in an IMx analyzer. RESULTS: Mean tHcy levels in transplant recipients were significantly higher than in controls (16.8+/-8.7 micromol/L and 9.5+/-2.3 micromol/L, respectively; P<0.01). A significant positive correlation between tHcy and serum creatinine levels was observed for both transplant recipients (rS=0.70, P<0.01) and controls (rS=0.54, P<0.01). In transplant recipients, tHcy correlated negatively with estimated GFR (rS=[minus]0.47, P<0.05). Fasting tHcy levels in excess of 14.6 micromol/L (>95th percentile in controls) were present in 19 (50%) patients; 14 of these patients had an estimated GFR<60 ml/min per 1.73 m2. When the renal transplant recipients were analyzed by renal function, mean tHcy was significantly higher in patients with an estimated GFR<60 ml/min per 1.73 m2 compared with patients with an estimated GFR> or =60 ml/min per 1.73 m2 (20.5+/-9.9 vs. 13.2+/-5.8 micromol/L, P<0.01). Both groups were significantly different from controls (P<0.01). No relationship was found between tHcy level and either cumulative cyclosporine or cumulative methylprednisone doses. No differences were observed in tHcy levels or lipoprotein profile between patients who were receiving deflazacort and those on methylprednisone. CONCLUSIONS: Hyperhomocysteinemia in renal transplant recipients is a common condition. Testing for fasting tHcy level might be a useful tool to identify patients at increased risk for development of vascular disease.     

Renal function and safety of heart transplant recipients switched to mycophenolate mofetil and low-dose cyclosporine

BACKGROUND: We evaluated cyclosporine (CSA) dose reduction and mycophenolate mofetil (MMF) treatment versus maintained CSA dosage and azathioprine (AZA) in HTX regarding renal function and safety from CSA nephrotoxicity (creatinine > 1.7 mg/dL). METHODS: Fourteen recipients (group 1: 12 men, 2 women) with CSA-based immunosuppression (plus azathioprine and/or steroids) were started on 2000 mg MMF/d. Azathioprine was discontinued and CSA tapered to trough whole blood levels of 70 to 120 microg/L. Ten recipients (group 2: seven men, three women) were maintained on their CSA dosages. Creatinine clearance, serum creatinine, uric acid, urea nitrogen, and rejection were monitored. RESULTS: Mean age was 58 (range 44 to 69 years) and 48 years (range 24 to 61 years) in groups 1 and 2, respectively. In group 1 creatinine fell from 2.7 +/- 0.8 to 1.9 +/- 0.5 mg/dL (baseline vs control 2: P =.001); uric acid and urea nitrogen remained constant. CSA levels decreased from 173 +/- 56 to 110 +/- 33 microg/L (P =.02). In group 2 creatinine (2.4 +/- 0.7 vs 2.3 +/- 0.5 mg/dL), uric acid, urea nitrogen, and CSA levels remained constant. Comparison between groups showed higher creatinine clearance (50 +/- 18 vs 29 +/- 14 mL/min; group 1 vs group 2: P =.02), lower CSA levels (110 +/- 33 vs 161 +/- 35 microg/L; P <.001) and a trend toward lower serum creatinine (1.9 +/- 0.5 vs 2.3 +/- 0.5 mg/dL, P =.077). There were two rejections >/= 1B according to ISHLT in the study and four in the control group. Two deaths occurred in each group. CONCLUSIONS: Conversion from AZA to MMF after CSA reduction improves creatinine clearance in HTX recipients and reduces serum creatinine. No negative effect on patient safety was identified by rejection rate or survival.     

Corticosteroid-free immunosuppression with daclizumab in HCV(+) liver transplant recipients: 1-year interim results of the HCV-3 study.

This work is a 1-yr interim analysis of a prospective, randomized, multicenter trial evaluating the effect of corticosteroid-free immunosuppression on hepatitis C virus-positive (HCV(+)) liver transplant recipients following liver transplantation (LT). Patients received tacrolimus and corticosteroids (Arm 1; n = 80); tacrolimus, corticosteroids, and mycophenolate mofetil (MMF) (Arm 2; n = 79); or daclizumab induction, tacrolimus, and MMF (Arm 3; n = 153). At 1 yr, 64.1%, 63.4%, and 69.4% of patients achieved the composite primary endpoint of freedom from rejection, freedom from HCV recurrence, and freedom from treatment failure, respectively. Excellent patient and graft survival did not differ significantly among treatment arms. Freedom from HCV recurrence at 1 yr was 61.8 +/- 6.2%, 60.1 +/- 6.1%, and 67.0 +/- 4.3% in Arms 1, 2, and 3, respectively (P = not significant). Freedom from rejection was significantly higher in Arm 3 compared to Arm 1 (93.0 +/- 2.2% vs. 81.9 +/- 4.4%; P = 0.011). Multivariate analysis identified acute rejection (hazard ratio = 2.692; P = 0.001) and donor age (hazard ratio = 1.015; P = 0.001) as significant risk factors for HCV recurrence. HCV recurrence was not influenced by recipient demographics, HCV genotype, or immunosuppression. In conclusion, these results suggest that a corticosteroid-free regimen of tacrolimus and MMF following daclizumab induction is safe and effective in HCV(+) liver transplant recipients.     

Serum total homocysteine and cardiovascular disease occurrence in chronic, stable renal transplant recipients: a prospective study

Renal transplant recipients have disproportionately high rates of arteriosclerotic outcomes, and recent studies provided controlled evidence that clinically stable renal transplant recipients have an excess prevalence of hyperhomocysteinemia. Few studies suggest that hyperhomocysteinemia may be a cardiovascular risk factor in renal transplant recipients. In the study presented here, the association between atherosclerotic events and homocysteine concentrations was examined in 207 stable renal transplant recipients. The role of hyperhomocysteinemia was analyzed with respect to other known cardiovascular risk factors. The mean follow-up was 21.2 +/- 1.9 mo (range, 14 to 26). Mean total homocysteine (tHcy) was 21.1 +/-9.5 micromol/L and median concentration was 19 micromol/L. Seventy percent of patients (n = 153) were hyperhomocysteinemic (values >15 micromol/L). tHcy correlated negatively with folate concentration (r = -0.3; P < 0.01). tHcy was closely related to creatinine concentration (r = 0.54; P < 0.001). Cardiovascular disease events (CVE) including death were observed in 30 patients (14.5 %; 7.34 events per 1000 person-months of follow-up). Fasting tHcy values were higher in patients who experienced CVE (31.5 +/- 10.3 versus 17.8 +/- 7.5; P < 0.001). Cox regression analysis showed that tHcy was a risk factor for cardiovascular complications (relative risk [RR] 1.06; 95% confidence interval (95% CI), 1.04 to 1.09; P < 0.0001). This corresponds to an increase in RR for CVE of 6% per micromol/L increase in tHcy concentration. Age (RR 1.55; 95% CI, 1.09 to 2.19; P < 0.01) and creatinine concentration (RR 1.34; 95% CI, 1.08 to 1.66; P < 0.01) were also independent predictors for CVE. This study demonstrates that elevated fasting tHcy is an independent risk factor for the development of CVE in chronic stable renal transplant recipients. Randomized, placebo-controlled homocysteine studies of the effect of tHcy lowering on CVE rates are urgently required in this patient population.     

Mycophenolate mofetil may allow cyclosporine and steroid sparing in de novo heart transplant patients

BACKGROUND: Mycophenolate mofetil (MMF) provides superior prophylaxis against acute rejection when compared with azathioprine (AZA) in heart and renal transplantation. However, it remains unclear whether this results in improved survival or reduced morbidity after heart transplantation. METHOD: In a sequential study, 240 cardiac transplant patients were treated with either MMF (n=119) or AZA (n=121) both in combination with cyclosporine and corticosteroids after rabbit antithymocyte globulin induction. RESULTS: By protocol lower cyclosporine levels were targeted in the MMF group during the first year (e.g. 203+/-52 ng/mL MMF vs. 236+/-59 ng/mL AZA, P=0.0006 at 6 months). Patient survival at 1 year (82% MMF vs. 79% AZA, P=0.55) and at 3 years was similar in both groups. The cumulative probability of receiving antirejection treatment within 1 year was lower in the MMF group, as was biopsy-proven acute rejection with International Society of Heart and Lung Transplantation grade > or =3A (24% vs. 35%, P=0.03). The MMF group also had fewer episodes requiring cytolytic therapy (6% vs. 13%, P=0.04) and more patients had steroids withdrawn by 1 year (66% vs. 32%, P<0.001). Renal function was better in the MMF group with lower creatinine levels at 1 year (133+/-45 vs. 155+/-46 micromol/L, P=0.0004). Calculated creatinine clearance (Cockcroft and Gault formula) at 1 year was also better (MMF 74+/-32 mL/min vs. AZA 62+/-24 mL/min, P=0.004). CONCLUSION: Our results suggest that immunosuppression with MMF rather than AZA may allow lower cyclosporine levels, better renal function, and increased steroid weaning at 1 year while also achieving better control of acute rejection.     

Results of kidney transplantation in patients receiving MMF- or MMF and basiliximab-containing immunosuppression

Mycophenolate mofetil (MMF) is a more potent immunosuppressive drug than azathioprine or mizoribine in combination with cyclosporine (CsA) and steroids. Recently, basiliximab (BA), an interleukin-2 receptor antagonist, has become available in Japan. The purpose of this study was to evaluate the efficacy of an extremely low CsA dose immunosuppressive protocol with MMF versus MMF plus BA after renal transplantation (RTx). PATIENTS: Between September 2001 and March 2003, we performed 79 RTx with CsA-based immunosuppression, including nine from cadavers and 70 from living donors with 15 ABO-incompatible RTx. Immunosuppression consisted of methylprednisolone (MP), CsA and MMF (group 1; n = 24) versus added BA during the induction phase (group 2; n = 55). In group 2, MP was withdrawn on postoperative day 14. Supplementary MP, muromonab-CD3, or gusperimus was administered if rejection was suspected clinically or diagnosed by biopsy. RESULTS: The incidence of biopsy-proven acute rejection (AR) was significantly higher among group 1 than group 2 patients (P < .05). CsA C2 levels in group 1 were significantly higher than group 2 at each time (P < .01). The incidence of infection was comparable. Patient and graft survival rates in group 1 were 100% and 100%; in group 2, they were 98% and 98%, respectively. CONCLUSION: The short-term results of RTx were favorable in both the MMF, and the MMF plus BA immunosuppression. In addition, BA significantly reduced the number of AR episodes. Early steroid withdrawal in recipients receiving BA induction was not associated with an increased risk of AR.     

B族维生素在肾移植受者高同型半胱氨酸血症及内皮功能异常治疗中的应用

目的探讨B族维生素治疗肾移植受者高同型半胱氨酸血症效果,对内皮功能的影响。方法将36例接受首次肾移植后的高同型半胱氨酸患者,随机分为两组,观察组18例,口服叶酸5mg/d,维生素B650mg/d及维生素B121000μg/d,连续6个月;对照组18例。分别于治疗前和治疗6个月时观察血肌酐水平和肌酐清除率,平均血压值,血胆固醇、甘油三酯和同型半胱氨酸水平变化,应用彩色多普勒超声测定内皮功能。结果观察组患者治疗后同型半胱氨酸与治疗前相比显著降低[(13±4)μmol/L与(20±5)μmol/L,t=5.3,P<0.01];肱动脉反应性充血时内径变化百分率[(12±5)%与(9±5)%,t=2.9,P<0.01]和含服硝酸甘油后肱动脉内径变化百分率[(18±4)%与(12±5)%,t=3.4,P<0.01]均显著增加。其他指标无显著改变。对照组6个月后各项指标与治疗前相比差异无统计学意义;肱动脉反应性充血时内径变化百分率为(9±6)%,含服硝酸甘油后肱动脉内径变化百分率为(12±5)%,均显著低于观察组(t=2.8,P<0.01;t=3.5,P<0.01)。结论应用叶酸、维生素B6及维生素B12能够有效治疗肾移植受者的高同型半胱氨酸血症,并使内皮功能获得明显改善。     

Levels of mycophenolic acid and its glucuronide derivative in the plasma of liver, small bowel and kidney transplant patients receiving tacrolimus and cellcept combination therapy

In order to help assess the usefulness of mycophenolate mofetil (MMF) as an immunosuppressive agent in recipients of organs other than kidneys, we measured the trough levels of the active metabolite of MMF, mycophenolic acid (MPA), and its inactive glucuronide derivative (MPAG), in the plasma of liver (n = 83) and small bowel transplant patients (n = 15) receiving MMF in combination with tacrolimus. These levels were compared with a group of renal transplant patients (n = 25) receiving the same drug regimen. All patient groups were otherwise comparable except the small bowel patient group which contained more pediatric patients (average age 18.7 +/- 3.9 years), and, therefore, received a higher average drug dose (in mg/kg). Despite this, these patients displayed the lowest levels of MPA of any group (0.39 +/- 0.08 microg/ml, P < 0.001 vs. 1.10 +/- 0.17 microg/ml for liver transplant patients, P < 0.001 or 2.46 +/- 0.37 microg/ml for renal transplant patients, P < 0.001). There were no statistically significant differences in MPAG levels between any of the groups. Although preliminary, these data demonstrate significant transplanted organ-specific differences in MMF pharmacology and/or bioavailability, and suggest the need for separate evaluation of MMF dosing for each transplant type.     

Effect of immunosuppressive therapy, serum creatinine, and time after transplant on plasma total homocysteine in patients following heart transplantation.

OBJECTIVES: To determine the prevalence of hyperhomocysteinemia in heart transplant recipients, and to assess the effect of renal function and immunosuppressive medication on total plasma homocysteine (tHcy) levels. BACKGROUND: Elevated plasma tHcy levels have been associated with increased risk of mortality in patients with established coronary artery disease. Graft coronary disease is the major cause of morbidity and mortality in long-term survivors of heart transplantation. The tHcy has been found to be elevated in heart and kidney transplant patients, however, the etiologic factors have not been clearly delineated. METHODS: The study group consisted of 70 heart transplant recipients (56 males, 14 females, mean age 53+/-13 years [range 17 to 69 years]). The parameters evaluated were fasting tHcy level, cumulative cyclosporine (CyA) dose, cumulative prednisone dose, serum creatinine, and time from transplantation. RESULTS: The mean fasting tHcy level was 20.5+/-10.2 micromol/L (range 5.2 to 59.0 micromol/L). Sixty-one (87%) had fasting tHcy levels greater than the seventy-fifth percentile of the general population (>12.2 micromol/L in males, and >10.1 micromol/L in females). There was no difference in mean post-transplant tHcy level between patients with and without coronary artery disease before transplantation (21.0+/-11.4 vs. 19.3+/-6.7 micromol/L, p = NS). There were significant relationships between the tHcy level and the serum creatinine (r = 0.76, p<0.001), and cumulative exposure to CyA (r = 0.31, p<0.01). There were no significant relationships between tHcy levels and cumulative prednisone dose, or time from transplantation. CONCLUSIONS: Fasting tHcy levels are markedly elevated in the majority of patients following heart transplantation, and are correlated to serum creatinine. Further studies are needed to determine other etiologic factors of elevated tHcy following heart transplantation, and to examine the impact of elevated tHcy on clinical outcomes.     

Mycophenolate mofetil tolerability and dose changes in tacrolimus-treated renal allograft recipients

Mycophenolate mofetil (MMF) reduces acute rejection episodes (AREs) and may be associated with better renal graft survival than azathioprine. However, MMF-related adverse events are frequent; dose reduction or even withdrawal are quite common. Between 1999 and 2003, 115 renal transplantation patients were treated with tacrolimus, MMF, and steroids. An observational study was undertaken until graft loss (n = 7), death with a functioning graft (n = 2), or October 31, 2005 (mean follow-up-50 months). We assessed MMF dose reductions due to adverse events with the possible consequences on AREs and graft function. Treated acute ARE occurred in 11.3% of recipients, all of which were steroid-responsive. The median MMF initial daily dose was 1000 mg. In 44 patients (38.3%), the MMF dose was not changed; in 48 (41.7%) it was reduced; and in 23 (20%), withdrawn. The causes for dose modification were diarrhea (n = 33, 28.7% of all patients), leukopenia (n = 22, 19.1%), both of these (n = 7, 6.1%), or other events (n = 9, 7.8%). No AREs were attributed to MMF dose changes. Tacrolimus blood levels were higher at 3 years and serum creatinine values at 4 years among patients with dose changes (8.43 +/- 2.42 vs 7.37 +/- 2.23 ng/mL; P = .051 and 1.75 +/- 0.71 vs 1.48 +/- 0.38 mg/dL; P = .038, respectively). The need for MMF dose reduction or withdrawal was frequent in our patients with diarrhea or leukopenia during treatment with tacrolimus, MMF, and steroids. These adverse event-related changes were not associated with AREs, but produced deleterious effects on long-term graft function.     

A prospective, randomized trial of tacrolimus in combination with sirolimus or mycophenolate mofetil in kidney transplantation: results at 1 year

BACKGROUND: This is the 1-year report of a randomized, multicenter, clinical trial comparing the combination of sirolimus or mycophenolate mofetil (MMF) with tacrolimus-based immunosuppression in kidney transplantation. METHODS: Prior to transplantation, recipients were randomized to receive tacrolimus plus corticosteroids with either sirolimus (n=185) or MMF (n=176). The incidence of biopsy-confirmed acute rejection at 6 months was the primary endpoint of the study. Patient and graft survival, renal function, study drug dosing and discontinuations were evaluated at 1 year. RESULTS: At 1 year, there was no difference in patient survival (95.7% sirolimus vs. 97.2% MMF; P=0.45) or graft survival (90.8% sirolimus vs. 94.3% MMF; P=0.22). Patients without delayed graft function (DGF) receiving MMF had significantly better graft survival (99% vs. 93%; P=0.01). Patients receiving a transplant from a live donor had a trend towards better graft survival with MMF as compared to sirolimus (98% vs. 91%; P=0.07). Patients receiving sirolimus had a significantly higher incidence of study drug discontinuation (26.5% vs. 14.8% MMF; P=0.006). Patients receiving MMF had significantly better renal function as shown by median serum creatinine levels (1.3 mg/dL vs. 1.5 mg/dL; P=0.03) and a trend towards higher calculated creatinine clearance (CrCl), (58.4 ml/min vs. 54.3 ml/min; P=0.06). More patients in the sirolimus group had a serum creatinine >2.0 mg/dL, (20.4% vs. 11.0%; P=0.02). CONCLUSIONS: Tacrolimus is safe and effective in live and deceased donor kidney transplantation when given in combination with sirolimus or MMF. Patient and graft survival were excellent in both arms. Renal function is superior for patients treated with tacrolimus + MMF combination.     

Treatment of hyperhomocysteinemia with folic acid reduces oxidative stress in renal transplant recipients

BACKGROUND: We conducted a prospective, uncontrolled, open study to assess the relationship between homocysteine (tHcy) and oxidative stress in chronic, stable, renal transplant recipients (RTR). METHODS: Included in the study were 17 chronic, stable RTR. All the patients received folic acid (5 mg/day). tHcy and total antioxidant capacity (TAOC) were measured before and at the end of the study period. RESULTS: Mean tHcy concentration was 26+/-10 micromol/L. tHcy significantly decreased during the study period (26+/-10 vs. 18+/-7 micromol/L; P<0.001). There was a significant inverse relationship between TAOC and tHcy (r= -0.33; P=0.01). TAOC significantly increased during the study period (1.49+/-0.23-1.78+/-0.6; P<0.001). There was an inverse relationship between the variation in tHcy and the variation in TAOC (r= -0.44; P=0.01). CONCLUSION: Our results demonstrate that hyperhomocysteinemia contributed to increased oxidative stress in RTR. tHcy-lowering treatment with folic acid may lower oxidative stress.     

Mycophenolate mofetil versus azathioprine for prevention of chronic allograft dysfunction in renal transplantation: the MYSS follow-up randomized, controlled clinical trial

The Mycophenolate Steroids Sparing (MYSS) study found that in renal transplant recipients who were on immunosuppressive therapy with the cyclosporine microemulsion Neoral, mycophenolate mofetil (MMF) was not better than azathioprine in preventing acute rejection at 21 mo after transplantation and was 15 times more expensive. The MYSS Follow-up Study, an extension of MYSS, was aimed at comparing long-term outcome of 248 MYSS patients according to their original randomization to MMF (1 g twice daily) or azathioprine (75 to 100 mg/d). Primary outcome was estimated GFR at 5 yr after transplantation. Mean 5-yr GFR difference between azathioprine and mycophenolate was 4.67 ml/min per 1.73 m(2) (95% confidence interval [CI] -0.43 to 9.77 ml/min per 1.73 m(2); P = 0.07). GFR from month 6 (mean +/- SEM: 54.3 +/- 1.6 versus 53.9 +/- 1.5 ml/min per 1.73 m(2); P = 0.83) to month 72 after transplantation (49.5 +/- 2.2 versus 47.3 +/- 2.4 ml/min per 1.73 m(2); P = 0.50); GFR slopes (mean +/- SEM: -1.10 +/- 0.56 versus -1.23 +/- 0.31 ml/min per 1.73 m(2) per year; P = 0.83); and 72-mo patient mortality (4.0 versus 4.0% [P = 0.95]; HR 0.96; 95% CI 0.28 to 3.31; P = 0.95), graft loss (6.8 versus 6.1% [P = 0.82]; HR 0.89; 95% CI 0.32 to 2.46; P = 0.83), incidence of persistent proteinuria (25.0 versus 27.4%; P = 0.72), late (>6 mo after transplantation) rejections (25.3 versus 21.2%; P = 0.53), and adverse events were similar on azathioprine (n = 124) and MMF (n = 124), respectively. Outcomes in the two groups were comparable also among patients with or without steroid therapy, considered separately. In kidney transplantation, the long-term risk/benefit profile of MMF and azathioprine therapy in combination with cyclosporine Neoral is similar. In view of the cost, standard immunosuppression regimens for kidney transplantation should perhaps include azathioprine rather than MMF.     

Folate supplementation inhibits intimal hyperplasia induced by a high-homocysteine diet in a rat carotid endarterectomy model

OBJECTIVE: Hyperhomocysteinemia has been implicated as a causative factor in intimal hyperplasia development. The addition of dietary folate in a hyperhomocysteinemia, carotid endarterectomy rat model is postulated to decrease plasma homocysteine levels and, in turn, reduce post-carotid endarterectomy intimal hyperplasia. METHODS: Each rat was fed one of six diets: (1) lab chow with no folate (n = 7), (2) lab chow with 10 mg/kg folate added (n = 3), (3) lab chow with 25 mg/kg folate added (n = 3), (4) a homocysteine diet with no folate (n = 7), (5) a homocysteine diet with 10 mg/kg folate added (n = 5), or (6) homocysteine diet with 25 mg/kg folate added (n = 5). Each rat then underwent an open carotid endarterectomy. In 2 weeks, intimal hyperplasia in the carotid artery was measured. Plasma homocysteine and folate levels were measured. RESULTS: Plasma folate levels rose with folate administration. Plasma homocysteine in the lab chow group was 5.4 +/- 0.5 micromol/L and did not change with the addition of folate. In the homocysteine diet group, plasma homocysteine rose 10-fold over the lab chow group (51.9 +/- 6.5 vs 5.4 +/- 0.5, micromol/L, P <.0001). In the group fed a homocysteine diet with 10 mg/kg folate added, a significant decrease in plasma homocysteine was observed (17.5 +/- 8.5 vs 51.9 +/- 6.5, micromol/L, P =.0003). In the group fed a homocysteine diet with 25 mg/kg folate added, plasma homocysteine levels were further reduced to levels seen in the lab chow group (12.6 +/- 2.6 vs 5.4 +/- 0.5, micromol/L, P = not significant). The relationship between plasma folate and homocysteine was inverse (R = 0.39, P =.0036). Luminal stenosis due to intimal hyperplasia was minimal in lab chow groups and unaffected by folate. The homocysteine diet group demonstrated post-carotid endarterectomy luminal stenosis due to intimal hyperplasia (60.9% +/- 9.2%). In the group fed a homocysteine diet with 10 mg/kg folate added, intimal hyperplasia was reduced, compared with the homocysteine diet group (32.6% +/- 7.4% vs 60.9% +/- 9.2%, P =.009). In the group fed a homocysteine diet with 25 mg/kg folate added, intimal hyperplasia was reduced to lab chow group levels (10.8% +/- 0.8% vs 4.8% +/- 1.0%, P = not significant) and was reduced, compared with the group fed a homocysteine diet with 10 mg/kg folate added. CONCLUSION: The use of folate in this hyperhomocysteinemia carotid endarterectomy model and the resultant attenuation of plasma homocysteine elevation and intimal hyperplasia development lend strong support to homocysteine being an independent etiologic factor in post-carotid endarterectomy intimal hyperplasia.     

Pharmacokinetics of mycophenolic acid in liver transplant patients after intravenous and oral administration of mycophenolate mofetil.

The bioavailability of mycophenolic acid (MPA) after oral administration of mycophenolate mofetil (MMF) has been reported to be more than 90% in healthy volunteers, and in kidney and thoracic organ transplant patients. Such information is limited in liver transplant (LTx) patients. The present study compares the pharmacokinetics of MPA after intravenous (IV) and oral administrations of MMF in LTx recipients. Pharmacokinetic parameters were calculated using WinNonlin software. A total of 12 deceased donor LTx patients initially received IV MMF and were switched to oral MMF after 2-7 days (mean, 3.3 +/- 1.7) when oral feeds were started. Multiple blood samples were drawn immediately prior to and after IV or oral MMF and the plasma concentration of MPA was measured. The mean peak plasma concentrations and the area under the plasma concentration vs. time curve (AUC) were significantly higher after IV MMF compared to oral MMF (peak plasma concentrations of 10.7 +/- 2.1 microg/mL for IV vs. 4.5 +/- 2.8 microg/mL for oral; P = 0.0001; and AUC of 28.9 +/- 7.1 microg . hr/mL for IV vs. 12.8 +/- 4.2 microg . hr/mL for oral; P = 0.0001). The oral bioavailability of MPA was 48.5 +/- 18.7%. The systemic clearance, half-life, and steady state volume of distribution of MPA were 26.9 +/- 6 L/hour, 5.5 hours, and 85 liters, respectively. The terminal disposition half-life was not significantly different between the 2 routes of administration. In conclusion, during the early postoperative period, LTx recipients have MPA exposure with oral MMF of less than half that of IV MMF. Use of IV MMF immediately post-LTx may provide an immunological advantage.     

Mycophenolate mofetil and sirolimus as calcineurin inhibitor-free immunosuppression for late cardiac-transplant recipients with chronic renal failure

BACKGROUND: Calcineurin-inhibitor (CNI)-related renal failure is a common problem after cardiac transplantation (HTx). The aim of this study was to introduce a CNI-free immunosuppressive regimen to HTx recipients with late posttransplant renal impairment and to evaluate the impact of conversion to this new immunosuppression (mycophenolate mofetil [MMF] and sirolimus [Sir]) treatment on renal function. METHODS AND RESULTS: Thirty-one HTx patients (25 men, 6 women; 0.2-14.2 years after transplantation) with CNI-based immunosuppression and a serum creatinine greater than 1.9 mg/dL were included in the study. Creatinine and cystatin levels were monitored to detect renal function. Mean patient age was 50+/-14 (range 19-74) years. Conversion was started with 6 mg Sir, continued with 2 mg, and the dose was adjusted to achieve target trough levels between 8 and 14 ng/mL. MMF was continued with trough level adjusted (1.5-4 microg/mL). Subsequently, the CNIs were tapered down and stopped. Clinical follow-up (first and every 3 months after conversion) included endomyocardial biopsies, echocardiography, and laboratory studies. Survival was 90% after a mean follow-up of 13+/-95 months. No acute rejection episode was detected during the study period. Renal function improved significantly after conversion: creatinine preconversion vs. postconversion: 3.14+/-0.76 mg/dL vs. 2.14+/-0.83 mg/dL, P =0.001. Cystatin preconversion vs. postconversion: 2.95+/-1.06 mg/L vs. 2.02+/-1.1 mg/L, P =0.01. In three patients, hemodialysis therapy was stopped completely after conversion. Graft function remained stable. Fractional shortening preconversion vs. postconversion: 36.9+/-6% vs. 36.4+/-6%. There were no serious adverse events. One patient had to be excluded because of noncompliance. CONCLUSIONS: Conversion from CNI-based immunosuppression to MMF and Sir in HTx patients with chronic renal failure was safe, preserved graft function, and improved renal function.     

High cysteine levels in renal transplant recipients: relationship with hyperhomocysteinemia and 5,10-MTHFR polymorphism

BACKGROUND: Long-term survival of renal transplant recipients seems to be influenced by the occurrence of thromboembolic complications and cardiovascular disease. Preliminary data available in the literature found high levels of cysteine (Cy) as a risk factor for deep venous thrombosis independently of high homocysteine (tHcy) levels, but no data are available about Cy levels in renal transplant recipients. METHODS: To investigate Cy, tHcy, and plasminogen activator inhibitor-1 (PAI-1) levels and the prevalence of 5,10-methylenetetrahydrofolate reductase (MTHFR) in renal transplantation, we studied 70 stable renal transplant recipients and 66 age- and sex-matched normal subjects as controls. RESULTS: Cy, tHcy, and PAI-1 levels were significantly higher in renal transplant recipients with respect to controls (Cy: 254 micromol/L [117-466] vs. 198 micromol/L [99-331], P<0.001; tHcy: 17.0 micromol/L [4.0-68] vs. 8.1 micromol/L [2.0-24.0], P<0.00001; PAI-1: 16.8 IU/ml [5.1-45.5] vs. 7.9 IU/ml [4.0-18.0], P<0.00001). High Cy levels were detected in 35.8% of patients. Hyperhomocysteinemia, both in the fasting state and postmethionine loading test, was diagnosed in 90% of cases. The odds ratios for Cy and tHcy levels within the fourth quartile with respect to the other quartiles were markedly increased in renal transplant recipients even after adjustment for prevalent cardiovascular risk factors, glomerular filtration rate, tHcy and, Cy, respectively (Cy: 29.0 micromol/L [95% CI 7.0-111]; tHcy: 29.9 micromol/L [95% CI 7.5-118.1]). Fasting tHcy levels correlated well with PAI-1 (r=0.65; P<0.0001) but not with Cy levels (r=0.10; P=0.4). The prevalence of the MTHFR 677TT genotype in renal transplant recipients was not significantly higher in patients than in controls (mutant allele frequency: 0.48 in patients and 0.47 in controls) and was associated with significantly higher fasting and postmethionine tHcy levels both in controls and patients. After 2 months of vitamin supplementation, tHcy (Pre: 17.0 micromol/L [4.0-68]; Post: 7.5 micromol/L [2.3-21.9]; P<0.0001) and PAI-1 levels (Pre: 16.8 IU/ml [5.1-45.5]; Post: 10 IU/ml [2.0-25]; P<0.001) were significantly decreased, whereas Cy levels showed a small decrease that did not reach statistical significance (Pre: 254 micromol/L [117-466]; Post: 209 micromol/L [168-300]; P=0.3). Patients with the MTHFR 677TT genotype had the major percentage of decrease of tHcy levels with respect to the other genotypes. CONCLUSION: In conclusion, this study demonstrates the presence of elevated Cy plasma levels in renal transplant recipients. Vitamin supplementation reduces tHcy but not Cy levels, and the amount of decrease seems to be influenced by the MTHFR genotype.     

Mycophenolate mofetil combination therapy improves long-term outcomes after liver transplantation in patients with and without hepatitis C.

To evaluate the impact of mycophenolate mofetil (MMF) on long-term outcomes of tacrolimus and corticosteroids, we analyzed data reported to the Scientific Registry of Transplant Recipients for 11,670 adult patients (3463 with hepatitis C [HCV]) who underwent primary, single-organ, liver transplantation between 1995 and 2001. Patients who were discharged from the hospital on tacrolimus-based immunosuppression with (n = 4466; n = 1323 HCV) or without MMF (n = 7204; n = 2140 HCV) were included in the analysis. Recipients treated at discharge with MMF, tacrolimus, and corticosteroids had significantly increased patient survival (81.0% vs. 77.0% at 4 years, P < 0.0001) and graft survival (76.4% vs. 72.9%, P < 0.0001), and lower rates of acute rejection (29.0% vs. 33.4%, P < 0.001) as compared to recipients treated at discharge with tacrolimus and corticosteroids alone. A trend toward lower rates of death from infection was observed (6.1% at 4 years for MMF vs. 7.1% at 4 years for tacrolimus and corticosteroids, P = 0.0508), but this result did not reach statistical significance. In multiple regression analyses, MMF triple therapy at discharge was associated with a reduced risk of death (hazard ratio [HR] = 0.77, P < 0.001), graft loss (HR = 0.81, P < 0.001), acute rejection (HR = 0.89, P = 0.002), and death from infectious complications (HR = 0.80, P = 0.007). Outcomes were similar for the cohort with HCV.In conclusion, the addition of MMF at discharge to tacrolimus-based immunosuppression is associated with improved long-term outcomes after liver transplantation in patients with and without HCV.