Increased Telomere Attrition After Renal Transplantation-Impact of Antimetabolite Therapy.

BACKGROUND: The uremic milieu exposes chronic kidney disease (CKD) patients to premature ageing processes. The impact of renal replacement therapy (dialysis and renal transplantation [RTx]) or immunosuppressive treatment regimens on ageing biomarkers has scarcely been studied. METHODS: In this study telomere length in whole blood cells was measured in 49 dialysis patients and 47 RTx patients close to therapy initiation and again after 12 months. Forty-three non-CKD patients were included as controls. RESULTS: Non-CKD patients had significantly (P ≤ 0.01) longer telomeres than CKD patients. Telomere attrition after 12 months was significantly greater in RTx patients compared to dialysis patients (P = 0.008). RTx patients receiving mycophenolate mofetil (MMF) had a greater (P = 0.007) degree of telomere attrition compared to those treated with azathioprine. After 12 months, folate was significantly higher in RTx patients than in dialysis patients (P < 0.0001), whereas the opposite was true for homocysteine (P < 0.0001). The azathioprine group had lower levels of folate after 12 months than the MMF group (P = 0.003). CONCLUSIONS: The associations between immunosuppressive therapy, telomere attrition, and changes in folate indicate a link between methyl donor potential, immunosuppressive drugs, and biological ageing. The hypothesis that the increased telomere attrition, observed in the MMF group after RTx, is driven by the immunosuppressive treatment, deserves further attention.

The efficacy of antigen-specific immunoadsorption and rebound of anti-A/B antibodies in ABO-incompatible kidney transplantation.

BACKGROUND: As antigen-specific immunoadsorption (IA) using the Glycosorb®-ABO columns is becoming increasingly popular in ABO-incompatible (ABOi) transplantation, in this study, we retrospectively investigated the efficacy of Glycosorb®-ABO IA in vivo and ex vivo. We also assessed the risk of anti-A/B antibody (ABab) rebound before and after ABOi kidney transplantation. METHODS: A protocol for ABOi living donor kidney transplantation was used, combining four preoperative and three preemptive postoperative Glycosorb®-ABO IAs with rituximab and maintenance immunosuppression. ABabs were determined by a haemagglutination titration technique. RESULTS: ABOi kidney transplantation was attempted 45 times and 43 transplantations were performed. Overall patient survival was 93% and graft survival was 91%. Mean follow-up was 4.5 years. Glycosorb®-ABO IA significantly reduced the ABabs in the majority of patients (P < 0.0001). However, in three patients (6.8%), the antibody elimination was incomplete. Inadequate adsorption of core-chain-dependent ABabs may explain this finding, but further studies are needed. In five patients, the preconditioning was interrupted before transplantation, resulting in ABab rebound. Yet, when preconditioning was restarted, the antibodies could be removed as planned. After ABOi transplantation, rebound of ABabs was seen in two patients (5%). CONCLUSIONS: Glycosorb®-ABO IA in combination with rituximab effectively depletes ABabs in most patients, but owing to core-chain-dependent ABabs, Glycosorb®-ABO IA may be less effective than nonspecific techniques for antibody removal in some patients. Rebound before transplantation subsequent to interrupted preconditioning does not hamper a successful ABOi transplantation. Postoperatively, when this protocol for ABOi transplantation is followed, the risk of ABab rebound is small.

Isoagglutinin adsorption in ABO-incompatible transplantation.

As the demand for kidney transplantation is constantly growing methods to expand the donor pool have become increasingly important. ABO-incompatibility has hitherto been regarded as an absolute contraindication to living donor donation. However, as ABO-incompatibility has accounted for the majority of living donor exclusions, efforts have been made to overcome this immunologic barrier. Successful desensitization protocols thus far, have combined plasmapheresis for antibody removal with splenectomy to reduce the antibody producing B-cell pool, in addition to quadruple immunosuppression. Although good graft function has been achieved, the high risks involved have been deterrent. We have developed a protocol for ABO-incompatible kidney transplantation based on antigen-specific immunoadsorption and rituximab, in combination with standard maintenance immunosuppression (tacrolimus, mycophenolate mofetil and corticosteroids). We hypothesized that the anti-A/B antibodies could be effectively eliminated and good graft function achieved, without the complications of coagulopathy and transfusion reactions associated with plasmapheresis. Furthermore, we hypothesized that the substitution of splenectomy with a single dose of the anti-CD20 antibody rituximab would further reduce surgical risk as well as the risk of infectious complications. In 2001 the program for ABO-incompatible kidney transplantation was started at our center. To date 50 ABO-incompatible kidney transplantations have been performed according to the protocol based on antigen-specific immunoadsorption and rituximab. Safety and efficacy of the protocol has been evaluated in several studies, all showing that the antigen-specific immunoadsorption is well tolerated and without any serious side effects. Patient and graft survival as well as kidney function have been comparable to that of ABO-compatible living donor kidney transplantation and the incidence of antibody-mediated rejection 0%. We conclude that AB0-incompatible kidney transplantation using a protocol based on antigen-specific immunoadsorption and rituximab, in combination with triple immunosuppressive therapy is safe and effective. ABO-incompatibility following this protocol does not have a negative impact on graft function. ABO-incompatible kidney transplantation is equivalent to standard ABO-compatible living donor kidney transplantation.

A randomized, doubleblind, placebo-controlled, study of single-dose rituximab as induction in renal transplantation.

UNLABELLED: We performed a prospective, double blind, randomized, placebo-controlled multicenter study on the efficacy and safety of rituximab as induction therapy, together with tacrolimus, mycophenolate mofetil, and steroids. The primary endpoint was defined as acute rejection, graft loss, or death during the first 6 months. Secondary endpoints were creatinine clearance, incidence of infections, and incidence of rituximab-related adverse event. RESULTS: We enrolled 140 patients (44 living donor and 96 deceased donor), and of those, 68 rituximab and 68 placebo patients fulfilled the study. In all the patients receiving rituximab, there was a complete depletion of CD19/CD20 cells, whereas there was no change in the number of CD19/CD20 cells in the placebo group. There were 10 treatment failures in the rituximab group versus 14 in the placebo group (P=0.348). There were eight rejection episodes in the rituximab group versus 12 in the placebo group (P=0.317) Creatinine clearance was 66+/-22 mL/min in the study group and 67+/-23 mL/min in the placebo group. There was no difference in the number of bacterial infections, cytomegalovirus infections, and BK virus infections or fungal infections. CONCLUSION: We performed a placebo-controlled study of rituximab induction in renal transplantation. There was a tendency toward fewer and milder rejections during the first 6 months in the rituximab group. Although induction with one dose of rituximab induced a complete depletion B cells, there was no increase in the incidence of infectious complications or leukopenia and it seems safe, therefore, to conduct further studies on the use of rituximab in transplantation.

ABO-incompatible kidney transplantation using antigen-specific immunoadsorption and rituximab: a 3-year follow-up.

BACKGROUND: In 2001 a protocol for ABO-incompatible (ABOi) kidney transplantation based on antigen-specific immunoadsorption and rituximab was introduced at our center, short-term results being comparable with those of ABO-compatible (ABOc) living donor kidney transplantation. Of greater importance, however, is long-term graft function, thus far not evaluated. The aim of this study was therefore to assess long-term results of this protocol. METHODS: Twenty ABOi kidney recipients with more than 12-month follow-up were included in the study: all adult crossmatch negative ABOi kidney recipients (n=15) were compared with an adult ABOc living donor recipient control group (n=30), and all pediatric ABOi kidney recipients (<16 years of age) (n=5) were compared with a group of pediatric ABOc kidney recipients (n=18). RESULTS: Mean follow-up was three years. There was no significant difference in patient survival, nor in graft survival or in the incidence of acute rejection in any of the groups. In the adult kidney recipients mean glomerular filtration rate was equivalent at all time points (79-83 mL/min), as was Deltas-creatinine. In the pediatric groups, Deltas-creatinine was similar but glomerular filtration rate lower among the ABOi kidney recipients. There was a significant reduction (P<0.0001) without rebound in A/B antibody titers after transplantation (median IgG 1:2 and median IgM 1:1>1 year posttransplant) compared with pretransplant levels (median IgG 1:32 and IgM 1:16). CONCLUSION: We conclude that ABOi kidney transplantation using antigen-specific immunoadsorption and rituximab is equivalent to ABOc living donor kidney transplantation. ABOi transplantation after this protocol does not have a negative impact on long-term graft function.

Implementation of a Protocol for ABO-incompatible kidney transplantation--a three-center experience with 60 consecutive transplantations.

BACKGROUND: A new protocol for ABO-incompatible kidney transplantation has recently been introduced. We report here on the joint experience of the implementation in Stockholm and Uppsala, Sweden and Freiburg, Germany. METHODS: The new protocol utilizes antigen-specific immunoadsorption to remove existing ABO-antibodies, rituximab, and intravenous immunoglobulin to prevent the rebound of antibodies, and conventional tacrolimus, mycophenolate-mofetil, and prednisolone immunosuppression. Sixty consecutive ABO-incompatible kidney transplantations were included in the study. The outcome is compared with the results of 274 ABO-compatible live donor transplantations performed during the same period. RESULTS: Two of the ABO-incompatible grafts have been lost (non-compliance and death with functioning graft). All the remaining 58 grafts had good renal function at a follow-up of up to 61 months. We did not observe any late rebound of antibodies and there were no humoral rejections. Graft survival was 97% for the ABO-incompatible compared with 95% for the ABO-compatible. Patient survival was 98% in both groups. There was a significant variation in preoperative A/B-antibody titer between the centers, with a median 1:8 in Uppsala, median 1:32 in Stockholm and median 1:128 in Freiburg. More preoperative antibody adsorptions were therefore needed in Freiburg than in Stockholm and Uppsala. CONCLUSIONS: The new protocol was easily implemented and there were no graft losses that could be related to ABO-incompatibility. A significant inter-institutional variation in the measurement of anti-AB-antibodies was found, having a substantial impact on the number of immunoadsorptions and consequently on the total cost for the procedure. A standardized fluorescence-activated cell sorting technique for antibody quantification is much needed.

Pharmacodynamics of rituximab in kidney transplantation.

The B-cell depleting anti-CD20 antibody rituximab has become a therapeutic alternative in renal transplantation. However, understanding of the pharmacodynamics is limited. We have therefore studied the effect of single-dose rituximab, in combination with conventional triple immunosuppressive therapy, on the B-cell population in peripheral blood as well as in tissues, in kidney transplant recipients. Forty-nine kidney recipients received single-dose rituximab. The prevalence of B cells was assessed in peripheral blood, kidney transplant tissue, and in lymph nodes. In 88%, complete depletion of B cells in peripheral blood was observed and, 15 months after treatment, B cells were still undetectable in the majority of patients. In kidney tissue, B cells were also completely eliminated. In contrast, the B cells were not eliminated in lymph nodes, although a reduction was observed. In conclusion, single-dose rituximab in kidney transplant recipients evokes a long-term elimination of B-cells in peripheral blood as well as within the kidney transplant.

Preapheresis immunosuppressive induction: necessary or harmful?

In ABO-incompatible kidney transplantation, only a few studies have addressed the necessity, duration, and content of immunosuppressive induction therapy. At our center (Karolinska Institute, Stockholm, Sweden), using a preconditioning regimen consisting of 13 days of tacrolimus, mycophenolate mofetil, and prednisolone, we have investigated both short- and long-term renal allograft function (up to 28 days and 1 year after transplantation, respectively) and correlated them to tacrolimus 12-hr trough levels. In summary, during the first 28 days after transplantation, renal allograft function in the ABO-incompatible group was impaired when compared with that observed in the ABO-compatible group. One possible explanation for this finding is the prolonged pretransplantation exposure to tacrolimus in the ABO-incompatible group, resulting in tacrolimus-associated renal toxicity, which slows the reduction in plasma creatinine. In fact, the day before, and also immediately after, the transplantation (for the first 3-4 postoperative days), the tacrolimus 12-hr trough levels in the ABO-incompatible group were greater than in the ABO-compatible group. Possibly, a shorter pretreatment period with tacrolimus or a reduced target tacrolimus trough level could eliminate this difference in postoperative renal allograft function. However, 1 year after transplantation, kidney allograft function in the two study groups was similar.

Long-term results of ABO-incompatible kidney transplantation with antigen-specific immunoadsorption and rituximab.

ABO-incompatible (ABOi) kidney transplantation has gained a renewed interest during the past years. In 2001, a protocol for ABOi kidney transplantation based on antigen-specific immunoadsorption and rituximab was introduced at our center. In this study long-term graft function using this protocol was assessed. All ABOi kidney recipients with >1-year follow-up (n=15) were compared with all ABO-compatible (ABOc) living donor kidney recipients maintained on the same basic immunosuppression (n=27). Patient and graft survival as well as rejections and calculated glomerular filtration rate were analyzed. Mean follow-up was 3 years. There was no significant difference in patient and graft survival nor in rejection episodes. Mean glomerular filtration rate (79-83 ml/min) was equivalent at 1, 2, and 3 years in both groups. We conclude that ABOi kidney transplantation using antigen-specific immunoadsorption and rituximab is equivalent to standard ABOc living donor kidney transplantation. ABOi transplantation following this protocol does not have a negative impact on graft function long-term.

The Stockholm experience with ABO-incompatible kidney transplantations without splenectomy.

BACKGROUND: ABO-incompatible kidney transplantations have previously only been performed after several pre-operative sessions of plasmapheresis followed by splenectomy, and with the conventional triple-drug immunosuppressive protocol being reinforced with anti-lymphocyte globulin and B-cell-specific drugs. We have designed a protocol without splenectomy, based on antigen-specific immunoadsorption, rituximab and a conventional triple-drug immunosuppressive protocol. METHODS: The protocol called for a 1-month pre-transplantation conditioning period, starting with one dosage of rituximab and followed by full-dose tacrolimus, mycophenolate mofetil and prednisolone. Antigen-specific immunoadsorption was performed on pre-transplantation days -6, -5, -2 and -1. After the last session, 0.5 g/kg of intravenous immunoglobulin (IVIG) was administered. Postoperatively, three more apheresis sessions were given every third day. RESULTS: Twenty-one patients have received transplants with this protocol. The ABO-antibodies (Abs) were readily removed by the antigen-specific immunoadsorption and were kept at a low level post-transplantation by further adsorptions. There were no side effects, and all but one patient have normal renal transplant function. CONCLUSIONS: We conclude that after one infusion each of rituximab and IVIG, and antigen-specific immunoadsorption, blood-group incompatible renal transplantations can be performed with standard immunosuppression and without splenectomy, and with excellent short- and long-term results.

Photopheresis for the treatment of refractory renal graft rejection.

Acute rejection episodes still occur after kidney transplantation in spite of modern immunosuppressive protocols including combined tacrolimus, mycophenolate mofetil, and prednisolone. The authors present seven cases of biopsy-proven acute rejection after kidney transplantation refractory to conventional rejection therapy with repeated pulses of high-dose steroids followed by polyclonal or monoclonal antibodies that responded well to photopheresis treatment. Photopheresis is an atoxic immunomodulatory apheresis-based treatment with no generalized immunosuppressive action; rather, it is directed at suppressing donor-specific T-cell clones. At the last follow-up, 9 to 43 months after transplantation, all patients had functioning grafts, with serum creatinine levels ranging from 105 to 312 microM. The authors conclude that photopheresis treatment contributed to the favorable outcome. Therefore, the authors are presently designing a prospective, randomized trial to evaluate the effect of photopheresis as an adjuvant prophylactic treatment after renal transplantation.

ABO incompatible kidney transplantations without splenectomy, using antigen-specific immunoadsorption and rituximab.

ABO incompatible kidney transplantations have previously only been performed after several preoperative sessions of plasmapheresis and splenectomy, with the conventional triple-drug immunosuppressive protocol being reinforced with antilymphocyte globulin and B-cell-specific drugs, such as cyclophosphamide or deoxyspergualine. We have designed a protocol without splenectomy, based on antigen-specific immunoadsorption, rituximab and a conventional triple-drug immunosuppressive protocol. The protocol calls for a 10-day pretransplantation conditioning period, starting with one dosage of rituximab and followed by full dose tacrolimus, mycophenolate mofetil and prednisolone. Antigen-specific immunoadsorption was performed on pretransplantation days -6, -5, -2 and -1. After the last session, 0.5 g/kg of intravenous immunoglobulin (IVIG) was administered. Postoperatively, three more apheresis sessions were given every third day. Furthermore, if there was a significant increase in the antibody titers, extra sessions were considered. Eleven patients have received transplants with this protocol. The ABO antibodies were readily removed by the antigen-specific immunoadsorption and were kept at a low level post-transplantation by further adsorptions. There were no side effects and all patients have normal renal transplant function. We conclude that after an infusion each of rituximab and IVIG, and antigen-specific immunoadsorption; blood group-incompatible renal transplantations can be performed with excellent results using standard immunosuppression and no splenectomy.