R. Snanoudj

Bortezomib as the Sole Post‐Renal Transplantation Desensitization Agent Does Not Decrease Donor‐Specific Anti‐HLA Antibodies

Persistence of donor‐specific anti‐HLA antibodies (DSA) associated with antibody‐mediated graft injuries following kidney transplantation predicts evolution toward chronic humoral rejection and reduced graft survival. Targeting plasma cells, the main antibody‐producing cells, with the proteasome inhibitor bortezomib may be a promising desensitization strategy. We evaluated the in vivo efficacy of one cycle of bortezomib (1.3 mg/m2× 4 doses), used as the sole desensitization therapy, in four renal transplant recipients experiencing subacute antibody‐mediated rejection with persisting DSA (>2000 [Mean Fluorescence Intensity] MFI). Bortezomib treatment did not significantly decrease DSA MFI within the 150‐day posttreatment period in any patient. In addition, antivirus (HBV, VZV and HSV) antibody levels remained stable following treatment suggesting a lack of efficacy on long‐lived plasma cells. In conclusion, one cycle of bortezomib alone does not decrease DSA levels in sensitized kidney transplant recipients in the time period studied. These results underscore the need to evaluate this new desensitization agent properly in prospective, randomized and well‐controlled studies.

Sirolimus May Reduce Fertility in Male Renal Transplant Recipients

Assessment of sex hormones in organ transplant recipients suggests that sirolimus may impair testicular function. The aim of this study was to evaluate the frequency and severity of sirolimus‐associated alterations in sperm parameters and their impact on fathered pregnancy rate. An observational study was carried out in male patients aged 20–40 years who received a kidney transplant during 1995–2005. Patients were sent a questionnaire by post, and sperm analysis was proposed. The fathered pregnancy rates according to the immunosuppressive regimen were estimated and compared using the Poisson model. Complete information was obtained from 95 out of 116 recipients. Patients treated with sirolimus throughout the post‐transplant period had a significantly reduced total sperm count compared to patients who did not receive sirolimus (28.6 ± 31.2 × 106 and 292.2 ± 271.2 × 106, respectively; p = 0.006), and a decreased proportion of motile spermatozoa (22.2 ± 12.3% and 41.0 ± 14.5%, p = 0.01). Moreover, the fathered pregnancy rate (pregnancies/1000 patient years) was 5.9 (95% CI, 0.8–42.1) and 92.9 (95% CI, 66.4–130.0) in patients receiving sirolimus‐based and sirolimus‐free regimens, respectively (p = 0.007). Of six patients in whom sirolimus treatment was interrupted, only three showed a significant improvement in sperm parameters. Sirolimus is associated with impaired spermatogenesis and, as a corollary, may reduce male fertility.

Specificity of histological markers of long-term CNI nephrotoxicity in kidney-transplant recipients under low-dose cyclosporine therapy.

The specificity of chronic histological lesions induced by calcineurin inhibitors (CNI) is often questioned, but few studies have directly compared long‐term lesions in renal‐transplant patients who received this treatment and those who did not. We therefore conducted a retrospective study of 141 kidney‐transplant recipients treated with (n = 48) or without (n = 93) cyclosporine (CsA) to compare the histological lesions observed at 3‐month, 24‐month and 10‐year protocol biopsies. All of the chronic elementary lesions (glomerulosclerosis, interstitial fibrosis, tubular atrophy, arteriolar hyalinosis, fibrointimal thickening) progressed in frequency and severity in both groups, although significantly more in the CsA group. Ten‐year biopsy results showed that 92% of patients in the CsA‐treated group and 65% in the control group had arteriolar hyalinosis lesions. When we focused on muscular arteriolar hyaline deposits more specific to CsA arteriolopathy, we observed these lesions in 68% of CsA patients and 28% of patients who had never received CsA. CsA was not the sole factor involved in the development of arteriolar hyalinosis and was independently associated with an increased risk of graft loss. In summary, we observed that histological lesions commonly attributed to CsA nephrotoxicity were not sufficiently specific to definitively diagnose CNI nephrotoxicity.

Donor-Estimated GFR as an Appropriate Criterion for Allocation of ECD Kidneys into Single or Dual Kidney Transplantation

It has been suggested that dual kidney transplantation (DKT) improves outcomes for expanded criteria donor (ECD) kidneys. However, no criteria for allocation to single or dual transplantation have been assessed prospectively. The strategy of DKT remains underused and potentially eligible kidneys are frequently discarded. We prospectively compared 81 DKT and 70 single kidney transplant (SKT) receiving grafts from ECD donors aged >65 years, allocated according to donor estimated glomerular filtration rate (eGFR): DKT if eGFR between 30 and 60 mL/min, SKT if eGFR greater than 60 mL/min. Patient and graft survival were similar in the two groups. In the DKT group, 13/81 patients lost one of their two kidneys due to hemorrhage, arterial or venous thrombosis. Mean eGFR at month 12 was similar in the DKT and SKT groups (47.8 mL/min and 46.4 mL/min, respectively). Simulated allocation of kidneys according to criteria based on day 0 donor parameters such as those described by Remuzzi et al., Andres et al. and UNOS, did not indicate an improvement in 12‐month eGFR compared to our allocation based on donor eGFR.

Incidence, Risk Factors and Clinical Consequences of Neutropenia Following Kidney Transplantation: A Retrospective Study

Neutropenic episodes in kidney transplant patients are poorly characterized. In this retrospective study, neutropenia was experienced by 112/395 patients (28%) during the first year posttransplant. The only factor found to be significantly associated with the occurrence of neutropenia was combined tacrolimus‐mycophenolate therapy (p < 0.001). Neutropenic patients experienced more bacterial infections (43% vs. 32%, p = 0.04). Grade of neutropenia correlated with the global risk of infection. Discontinuation of mycophenolic acid (MPA) due to neutropenia was associated with an increased incidence of acute rejection (odds ratios per day 1.11, 95% confidence intervals 1.02–1.22) but not with reduced renal function at 1 year. The time from onset of neutropenia to MPA discontinuation correlated with the duration of neutropenia. Granulocyte colony‐stimulating factor (G‐CSF) administration was safe and effective in severely neutropenic kidney graft recipients, with absolute neutrophil count >1000/μL achieved in a mean of 1.5±0.5 days. Neutropenia is an important and frequent laboratory finding that may exert a significant influence on outcomes in kidney transplantation. As well as leading to an increased incidence of infection, it is associated with a higher rate of allograft rejection if MPA is discontinued for >6 days (p = 0.02). G‐CSF accelerates recovery of neutropenia and may be a good therapeutic alternative for severely neutropenic patients.

Five-Year Results of a Randomized Trial Comparing De Novo Sirolimus and Cyclosporine in Renal Transplantation: The Spiesser Study

Calcineurin inhibitors improve acute rejection rates and short‐term graft survival in renal transplantation, but their continuous use may be deleterious. We evaluated the 5‐year outcomes of sirolimus (SRL) versus cyclosporine (CsA) immunosuppressive treatment. This observational study was an extension of the SPIESSER study where deceased donor kidney transplant recipients were randomized before transplantation to a SRL‐ or CsA‐based regimen and followed up 1 year. Data from 131 (63 SRL, 68 CsA) out of 133 patients living with a functional graft at 1 year were collected retrospectively at 5 years posttransplant. Seventy percent of CsA patients versus 54% of SRL patients were still on the allocated treatment at 5 years (p = 0.091), most discontinuations in each group being due to safety issues. In intent‐to‐treat, mean MDRD eGFR was higher with SRL: 54.2 versus 45.3 mL/min with CsA (p = 0.019); SRL advantage was greater in on‐treatment analyses. There were no differences for patient survival (p = 0.873), graft survival (p = 0.121) and acute rejection (p = 0.284). Adverse events were more frequent with SRL (80% vs. 60%, p = 0.015). Results confirmed the high SRL discontinuation rate due to adverse events. Nevertheless, a benefit was evidenced on renal function in patients (more than 50%) still on treatment at 5 years.

Outcome of kidney transplantations performed with preformed donor-specific antibodies of unknown etiology.

The detection of preformed donor‐specific alloantibodies (DSA) with multiplex‐bead arrays has led to the common observation that individuals without a history of pregnancy, transfusion or transplantation can have circulating anti‐HLA antibodies of unknown etiology. We retrospectively analyzed the risk of antibody‐mediated rejection (AMR) and graft outcome in 41 kidney transplant recipients with DSA of unknown etiology (DSA cause‐unk) at the time of transplantation. Twenty‐one patients received a posttransplantation desensitization protocol, and 20 received standard immunosuppressive therapy. The mean number of DSA was 1.4 ± 0.8, ranging from 1 to 5. Complement‐dependent cytotoxicity crossmatches were negative for all the patients. Flow cytometry crossmatches were positive in 47.6% of cases. The incidence of acute AMR was 14.6% at 1 year, regardless of the immunosuppressive regimen. No patients experienced graft loss following AMR. At month 12, across the entire population of patients with DSA cause‐unk, the outcomes were favorable: the measured glomerular filtration rate was 63.8 ± 16.4 mL/min/1.73 m2, the screening biopsies showed low frequencies of microvascular inflammation and no transplant glomerulopathy, and graft and patient survival were 100%. In conclusion, patients with DSA cause‐unk are able to mount AMR but have favorable 1‐year outcomes.

Co-stimulation Blockade as a New Strategy in Kidney Transplantation: Benefits and Limits

New immunosuppressive drugs have greatly decreased the frequency of graft failure due to acute rejection but have had little impact on long-term graft survival. This is due, at least in part, to the broad non-immune effects of the current immunosuppressive drugs, which are involved in the death of patients and in chronic allograft dysfunction, particularly due to their nephrotoxicity. Recent progress in the development of biologicals, i.e. antibodies and fusion proteins, allows precise targeting of the immune system, preventing the non-immune side effects encountered with current protocols. In particular, targeting of the two most important co-stimulation pathways critical for T-cell activation, i.e. B7/CD28 and CD40/CD40L, has provided excellent results in many experimental models of organ transplantation. This has led to the clinical development of belatacept, a cytotoxic T-lymphocyte-associated antigen 4 immunoglobulin (CTLA4-Ig) fusion protein, which has proved to be efficient in preventing acute rejection in kidney transplant recipients. Its use is associated with improved renal function and a better metabolic profile than calcineurin inhibitors. However, because belatacept does not selectively target alloreactive T lymphocytes and must be combined with classical immunosuppressive drugs, infectious and neoplastic complications may occur, particularly post-transplantation lymphoproliferative disorders. We also address the current development of molecules targeting other costimulatory pathways (CD40/CD40L, leukocyte function-associated antigen [LFA]-1/intercellular adhesion molecule [ICAM], CD2/LFA-3). Many unresolved issues regarding the use of co-stimulation blocking agents are also discussed, e.g. their long half-life, which can be problematic in cases of serious adverse events, their long-term safety and efficacy, and the lack of monitoring tools to allow modulation of their use over time.

FOXP3-enriched infiltrates associated with better outcome in renal allografts with inflamed fibrosis

BACKGROUND FOXP3-expressing regulatory T cells (Tregs) play a crucial role in maintaining allogeneic transplant tolerance in experimental models. In clinical transplantation, there are few data about their role in chronic inflammation. We hypothesized that Tregs might accumulate within the graft since enrichment of Tregs has been frequently described in chronically inflamed tissues. METHODS Sixty-seven biopsies, indicated by a rise in creatinine level, were studied. Thirty-four biopsies showing acute T-cell-mediated rejection and 33 displaying inflamed fibrosis were selected. Tregs frequency was calculated for each infiltrate by counting FOXP3+ and CD3+ cells on two contiguous serial sections. RESULTS A total of 121 infiltrates were scored with a mean of 309 CD3+ cells per infiltrate (range: 50-700). Tregs were enriched within allografts exhibiting inflamed fibrosis versus acute cellular rejection (10.6 +/- 6.8% versus 5.5 +/- 2.6%, respectively, P = 0.005). In those with inflammation within scarred areas, the subset of patients with a low FOXP3/CD3 ratio (below the median value) displayed a lower frequency of B-cell-enriched nodular cell clusters (20% versus 86%, P = 0.001) and had a significantly lower graft survival (log-rank, P = 0.02). In multivariate analysis, the low FOXP3/CD3 ratio remained an independent indicator of outcome (P = 0.03). Consistently, the FOXP3+/IL-17+ cell ratio was higher in nodular than in diffuse infiltrates. CONCLUSIONS Our results suggest that Tregs may dampen the graft injury in chronic (versus acute) inflammation and stress the importance of devising strategies to enhance Tregs efficiency.

Risk of antibody-mediated rejection in kidney transplant recipients with anti-HLA-C donor-specific antibodies.

Anti‐HLA donor‐specific antibodies (DSAs) cause acute and chronic antibody‐mediated rejection (AMR). However, the clinical relevance of anti‐HLA‐C antibodies remains unclear. We evaluated the clinical relevance of the presence of anti‐HLA‐C DSA at day 0 in renal transplant recipients. In this retrospective, case‐controlled study, 608 patients who underwent kidney transplantation between August 2008 and March 2012 were screened for the presence of isolated anti‐HLA‐C DSA at day 0. A total of 22 renal transplant recipients were selected and followed for a period of 1 year. AMR was classified according to the Banff classification. The 22 patients were compared with 88 immunized patients. Acute AMR was diagnosed in six patients (27.3%). The median level of DSA at day 0 was 1179 (530–17 941). The mean fluorescence intensity in the anti‐C group was 4966 (978–17 941) in the AMR group and 981 (530–8012) in the group of patients without AMR. Acute AMR was diagnosed less frequently in the 88 immunized individuals (9.1%) than in the DSA anti‐C group (p = 0.033). The level of DSA at day 0 was predictive for AMR (p = 0.017). Patients with a high level of pretransplant anti‐HLA‐C DSAs are likely to develop acute AMR during the first year after transplantation.