Luuk B. Hilbrands

Withdrawal of Cyclosporine or Prednisone Six Months after Kidney Transplantation in Patients on Triple Drug Therapy: A Randomized, Prospective, Multicenter Study

Uncertainty exists regarding the necessity of continuing triple therapy consisting of mycophenolate mofetil (MMF), cyclosporine (CsA), and prednisone (Pred) after kidney transplantation (RTx). At 6 mo after RTx, 212 patients were randomized to stop CsA (n = 63), stop Pred (n = 76), or continue triple drug therapy (n = 73). The MMF dose was 1000 mg twice daily, target CsA trough levels were 150 ng/ml, and Pred dose was 0.10 mg/kg per d. Follow-up was until 24 mo after RTx. Biopsy-proven acute rejection occurred in 14 (22%) of 63 patients after CsA withdrawal compared with 3 (4%) of 76 in the Pred withdrawal group (P = 0.001) and 1 (1.4%) of 73 in the control group (P = 0.0001). Biopsy-proven chronic rejection was present in one patient in the control group, in nine patients after CsA withdrawal (P = 0.006 versus control group); and in four patients after discontinuation of Pred (NS). Graft loss occurred in two versus one patient after CsA or Pred withdrawal, respectively, and in two patients in the control group (NS). Patients who successfully withdrew CsA had a significantly lower serum creatinine during follow-up. Pred withdrawal resulted in a reduction in mean arterial pressure, and the total cholesterol/HDL ratio increased. In conclusion, rapid CsA withdrawal at 6 mo after RTx results in a significantly increased incidence of biopsy-proven acute and chronic rejection. Pred withdrawal was safe and resulted in a reduction in mean arterial pressure. However, patient and graft survival and renal function 2 yr after RTx were not different among groups.

Conversion from Cyclosporine to Tacrolimus Improves Quality of Life Indices, Renal Graft Function and Cardiovascular Risk Profile

Long‐term use of cyclosporine after renal transplantation results in nephrotoxicity and an increased cardiovascular risk profile. Tacrolimus may be more favorable in this respect. In this randomized controlled study in 124 renal transplant patients, the effects of conversion from cyclosporine to tacrolimus on renal function, cardiovascular risk factors, and perceived side‐effects were investigated after a follow‐up of 2 years. After conversion from cyclosporine to tacrolimus renal function remained stable, whereas continuation of cyclosporine was accompanied by a rise in serum creatinine from 142 ± 48 μmol/L to 157 ± 62 μmol/L (p < 0.05 comparing both groups). Conversion to tacrolimus resulted in a sustained reduction in systolic and diastolic blood pressure, and a sustained improvement in the serum lipid profile, leading to a reduction in the Framingham risk score from 5.7 ± 4.3 to 4.8 ± 5.3 (p < 0.05). Finally, conversion to tacrolimus resulted in decreased scores for occurrence of and distress due to side‐effects. In conclusion, conversion from cyclosporine to tacrolimus in stable renal transplant patients is beneficial with respect to renal function, cardiovascular risk profile, and side‐effects. Therefore, for most renal transplant patients tacrolimus will be the drug of choice when long‐term treatment with a calcineurin inhibitor is indicated.

Sirolimus-associated heavy proteinuria in a renal transplant recipient: evidence for a tubular mechanism.

Sirolimus is a new and potent immunosuppressive agent. Recently, increased proteinuria has been recognized as an important complication. However, the mechanism thereof has remained unclear. We describe a patient who received sirolimus as standard therapy after living donor kidney transplantation. Within 10 days the patient developed a severe proteinuria that disappeared completely after substituting tacrolimus for sirolimus. Renal biopsy disclosed normal glomeruli even without effacement of the podocytic foot processes. Using FITC labeled anti‐albumin antibodies we noted complete absence of albumin in the proximal tubules, whereas an abundant albumin staining was observed in a control patient with a comparable level of proteinuria due to a recurrence of focal segmental glomerulosclerosis after transplantation. Our data suggest that sirolimus can induce severe proteinuria, and that reduced tubular protein reabsorption contributes to the protein loss.

Improved Cardiovascular Risk Profile and Renal Function in Renal Transplant Patients after Randomized Conversion from Cyclosporine to Tacrolimus

Cyclosporine is considered to contribute to the high cardiovascular morbidity and mortality in patients after renal transplantation. Tacrolimus may be more favorable in this respect, but controlled data are scarce. In this prospective randomized study in 124 stable renal transplant patients, the effects of conversion from cyclosporine to tacrolimus on cardiovascular risk factors and renal function were investigated. Follow-up was 6 mo. Statistical analysis was performed by ANOVA for repeated measurements. The serum creatinine level decreased from 137 +/- 30 micromol/L to 131 +/- 29 micromol/L (P < 0.01). Three months after conversion from cyclosporine to tacrolimus, mean BP significantly decreased from 104 +/- 13 to 99 +/- 12 mmHg (P < 0.001). Serum LDL cholesterol decreased from 3.48 +/- 0.80 to 3.11 +/- 0.74 mmol/L (P < 0.001,) and serum apolipoprotein B decreased from 1018 +/- 189 to 935 +/- 174 mg/L (P < 0.001). Serum triglycerides decreased from 2.11 +/- 1.12 to 1.72 +/- 0.94 mmol/L (P < 0.001). In addition, both rate and extent of LDL oxidation were reduced. The fibrinogen level decreased from 3638 +/- 857 to 3417 +/- 751 mg/L (P < 0.05). Plasma homocysteine concentration did not change. Three months after conversion, plasma fasting glucose level temporarily increased from 5.4 +/- 1.3 mmol/L to 5.8 +/- 1.9 mmol/L (P < 0.05). Conversion to tacrolimus resulted in a significant reduction of the Framingham risk score. In conclusion, conversion from cyclosporine to tacrolimus in stable renal transplant patients has a beneficial effect on renal function, BP, serum concentration and atherogenic properties of serum lipids, and fibrinogen.

Dendritic cells activated by lipopolysaccharide after dexamethasone treatment induce donor-specific allograft hyporesponsiveness.

Background. Immature dendritic cells (imDC) can prolong allograft survival in murine transplantation models. Recent data indicate that semi-mature or alternatively activated DC (aaDC) may be even more tolerogenic. Methods. We compared the phenotype and regulatory capacity of: a) imDC, cultured in the presence of dexamethasone (DEX), b) mature DC (matDC), activated with LPS, and c) aaDC, activated with LPS after pretreatment with DEX. Results. As compared to imDC, aaDCs displayed a slight upregulation of CD40 while expression levels of MHC-II and CD86 remained low. The production of proinflammatory cytokines, in particular IL-12, by aaDC was much lower than by matDC while both produced similar amounts of the regulatory cytokine IL-10 leading to an increased IL-10/IL-12 ratio for aaDC. After infusion of donor type aaDCs, responder cells isolated from the recipient mice showed donor-specific hyporesponsiveness to restimulation by matDC. Infusion of matDC was immunogenic, while imDC induced partial hyporesponsiveness. Importantly, pretreatment with donor type aaDC (but not imDC) resulted in prolonged survival of a completely MHC-mismatched heart allograft. Conclusions. Alternatively activated DC are more efficacious than the classical imDC in the regulation of the alloimmune response, which may be related to a distinct cytokine profile characterized by an increased IL-10/IL12 ratio.

Population pharmacokinetics of mycophenolic acid : a comparison between enteric-coated mycophenolate sodium and mycophenolate mofetil in renal transplant recipients.

AbstractObjective: The pharmacokinetics of mycophenolic acid (MPA) were compared in renal transplant patients receiving either mycophenolate mofetil (MMF) or enteric-coated mycophenolate sodium (EC-MPS). Methods: MPA concentration-time profiles were included from EC-MPS- (n = 208) and MMF-treated (n = 184) patients 4–257 months after renal transplantation. Population pharmacokinetic analysis was performed using nonlinear mixed-effects modelling (NONMEM®). A two-compartment model with first-order absorption and elimination was used to describe the data. Results: No differences were detected in MPA clearance, intercompartmental clearance, or the central or peripheral volume of distribution. Respective values and interindividual variability (IIV) were 16 L/h (39%), 22 L/h (78%), 40 L (100%) and 518 L (490%). EC-MPS was absorbed more slowly than MMF with respective absorption rate constant values of 3.0 h−1 and 4.1 h−1 (p < 0.001) [IIV 187%]. A mixture model was used for the change-point parameter lag-time (tlag) in order to describe IIV in this parameter adequately for EC-MPS. Following the morning dose of EC-MPS, the tlag values were 0.95, 1.88 and 4.83 h for 51%, 32% and 17% of the population (IIV 8%), respectively. The morning tlag following EC-MPS administration was significantly different from both the tlag following MMF administration (0.30 h; p < 0.001 [IIV 11%]) and the tlag following the evening dose of EC-MPS (9.04 h; p < 0.001 [IIV 40%]). Post hoc analysis showed that the tlag was longer and more variable following EC-MPS administration (morning median 2.0 h [0.9–5.5 h], evening median 8.9 h [5.4–12.3 h]) than following MMF administration (median 0.30 h [0.26–0.34 h]; p < 0.001). The morning MPA predose concentrations were higher and more variable following EC-MPS administration than following MMF administration, with respective values of 2.6 mg/L (0.4–24.4 mg/L) and 1.6 mg/L (0.2–7.6 mg/L). The correlation between predose concentrations and the area under the plasma concentration-time curve (AUC) was lower in EC-MPS-treated patients (r2 = 0.02) than in MMF-treated patients (r2 = 0.48). Conclusion: Absorption of MPA was delayed and also slower following EC-MPS administration than following MMF administration. Furthermore, the tlag varied more in EC-MPS-treated patients. MPA predose concentrations were poorly correlated with the MPA AUC in both MMF- and EC-MPS-treated patients.

A single dose of rituximab does not deplete B cells in secondary lymphoid organs but alters phenotype and function

A single dose of the anti‐CD20 monoclonal antibody rituximab induces a nearly complete B cell depletion in peripheral blood, but not in secondary lymphoid organs. Modulation of this remaining B cell population due to rituximab treatment may contribute to the therapeutic effects of rituximab. To assess the in vivo effects of rituximab we used lymph nodes (LNs) collected during renal transplant surgery in patients who had received rituximab 4 weeks earlier in preparation for an ABO‐incompatible transplantation. Rituximab treatment resulted in a lower percentage of naïve (IgD+CD27−) and a higher percentage of switched memory (IgD−CD27+) B cells. Remarkably, transitional (CD24++CD38++) B cells were virtually lacking in the LNs of rituximab‐treated patients. Moreover, LN‐derived B cells from rituximab‐treated patients produced different amounts of various Ig‐subclasses after anti‐CD40/IL‐21 stimulation ex vivo. Finally, after stimulation of allogeneic T cells with LN‐derived B cells from rituximab‐treated patients, the proliferated T cells showed a decreased production of IL‐17. In conclusion, after treatment with rituximab there remains a B cell population with different functional capacities. Consequently, the effect of rituximab on the immune response will not only be determined by the extent of B cell depletion, but also by the functional properties of the remaining B cells.

Circulating Apoptotic Microparticles in Systemic Lupus Erythematosus Patients Drive the Activation of Dendritic Cell Subsets and Prime Neutrophils for NETosis

Circulating chromatin‐containing apoptotic material and/or neutrophil extracellular traps (NETs) have been proposed to be an important driving force for the antichromatin autoimmune response in patients with systemic lupus erythematosus (SLE). The aim of this study was to determine the exact nature of microparticles in the circulation of SLE patients and to assess the effects of the microparticles on the immune system.

Rituximab as induction therapy after renal transplantation: a randomized, double-blind, placebo-controlled study of efficacy and safety

We evaluated the efficacy and safety of rituximab as induction therapy in renal transplant patients. In a double‐blind, placebo‐controlled study, 280 adult renal transplant patients were randomized between a single dose of rituximab (375 mg/m2) or placebo during transplant surgery. Patients were stratified according to panel‐reactive antibody (PRA) value and rank number of transplantation. Maintenance immunosuppression consisted of tacrolimus, mycophenolate mofetil and steroids. The primary endpoint was the incidence of biopsy proven acute rejection (BPAR) within 6 months after transplantation. The incidence of BPAR was comparable between rituximab‐treated (23/138, 16.7%) and placebo‐treated patients (30/142, 21.2%, p = 0.25). Immunologically high‐risk patients (PRA >6% or re‐transplant) not receiving rituximab had a significantly higher incidence of rejection (13/34, 38.2%) compared to other treatment groups (rituximab‐treated immunologically high‐risk patients, and rituximab‐ or placebo‐treated immunologically low‐risk (PRA ≤ 6% or first transplant) patients (17.9%, 16.4% and 15.7%, p = 0.004). Neutropenia (<1.5 × 109/L) occurred more frequently in rituximab‐treated patients (24.3% vs. 2.2%, p < 0.001). After 24 months, the cumulative incidence of infections and malignancies was comparable. A single dose of rituximab as induction therapy did not reduce the overall incidence of BPAR, but might be beneficial in immunologically high‐risk patients. Treatment with rituximab was safe.

Circulating apoptotic microparticles in SLE patients drive the activation of DC subsets and prime neutrophils for NETosis

Circulating chromatin‐containing apoptotic material and/or neutrophil extracellular traps (NETs) have been proposed to be an important driving force for the antichromatin autoimmune response in patients with systemic lupus erythematosus (SLE). The aim of this study was to determine the exact nature of microparticles in the circulation of SLE patients and to assess the effects of the microparticles on the immune system.