Isabelle Binet

Polyomavirus disease under new immunosuppressive drugs : A cause of renal graft dysfunction and graft loss

BACKGROUND Manifest polyomavirus (PV) renal graft infection is a rare complication. We diagnosed 5 cases among 70 kidney recipients undergoing transplants since December 1995; however, there were no cases at our institution before December 1995. METHOD To identify risk factors promoting manifest PV graft infection, we compared those 5 patients with kidney recipients who had signs of PV replication but no manifest graft infection (n=23, control group). PV replication was judged by the presence of intranuclear inclusion cells in the urine. RESULTS Before the infection, five of five patients had recurrent rejection episodes. All were switched from cyclosporine A to high dose tacrolimus as rescue therapy. Infection was diagnosed histologically 9+/-2 months posttransplantation; it persisted and led to graft loss in four of five patients. In control patients, graft function was stable, 1 of 23 patients were switched to tacrolimus as rescue therapy, and graft loss occurred in 4 of 23 patients. CONCLUSION Recurrent rejection episodes and high dose immunosuppressive therapy, including tacrolimus, are risk factors for manifest PV kidney graft infection, which has an ominous prognosis.

Polyomavirus BK-Specific Cellular Immune Response to VP1 and Large T-Antigen in Kidney Transplant Recipients

Polyomavirus BK (BKV) is the primary cause of polyomavirus‐associated nephropathy (PVAN) in kidney transplant (KT) recipients. Using ELISpot assays, we compared the frequency of interferon‐γ (IFN‐γ) secreting peripheral blood mononuclear cells (PBMC) after stimulation with overlapping peptide pools covering BKV large T‐antigen (LT) and VP1 capsid proteins (VP1). In 10 healthy donors, LT and VP1 responses were low with median 24 (range 15–95) and 25 (7–113) spot‐forming units/106 PBMC (SFU), respectively. In 42 KT patients with current or recent plasma BKV loads, median LT and VP1 responses of 29 (0–524) and 114 (0–1432) SFU were detected, respectively. In KT patients with decreasing or past plasma BKV loads, significantly higher median BKV‐specific IFN‐γ responses were detected compared to KT patients with increasing or persisting BKV loads [LT: 78 (8–524) vs. 22 (0–120) SFU, p = 0.003; VP1: 285 (45–1432) vs. 53 (0–423) SFU, p = 0.001, respectively]. VP1‐specific IFN‐γ responses were higher and more likely to involve CD4+ T cells, while CD8+ T cells were more frequently directed against LT. Stimulation with JCV‐specific VP1 and LT peptides indicated only low‐level cross‐recognition. The data suggest that control of BKV replication is correlated with differentiated expansion of BKV‐specific cellular immune responses.

Increases in kidney volume in autosomal dominant polycystic kidney disease can be detected within 6 months

Kidney volume growth is considered the best surrogate marker predicting the decline of renal function in autosomal dominant polycystic kidney disease. To assess the therapeutic benefit of new drugs more rapidly, changes in kidney volume need to be determined over a short time interval. Here we measured renal volume changes by manual segmentation volumetry applied to magnetic resonance imaging scans obtained with an optimized T1-weighted acquisition protocol without gadolinium-based contrast agents. One hundred young patients with autosomal dominant polycystic kidney disease and preserved renal function had a significant increase in total kidney volume by 2.71+/-4.82% in 6 months. Volume measurements were highly reproducible and accurate, as indicated by correlation coefficients of 1.000 for intra-observer and 0.996 for inter-observer agreement, with acceptable within-subject standard deviations. The change in renal volume correlated with baseline total kidney volume in all age subgroups. Total kidney volume positively correlated with male gender, hypertension, albuminuria and a history of macrohematuria but negatively with creatinine clearance. Albuminuria was associated with accelerated volume progression. Our study shows that increases in kidney volume can be reliably measured over a 6 month period in early autosomal dominant polycystic kidney disease using unenhanced magnetic resonance imaging sequences.

Cytomegalovirus-specific T-cell responses and viral replication in kidney transplant recipients

BackgroundCytomegalovirus (CMV) seronegative recipients (R-) of kidney transplants (KT) from seropositive donors (D+) are at higher risk for CMV replication and ganciclovir(GCV)-resistance than CMV R(+). We hypothesized that low CMV-specific T-cell responses are associated with increased risk of CMV replication in R(+)-patients with D(+) or D(-) donors.MethodsWe prospectively evaluated 73 consecutive KT-patients [48 R(+), 25 D(+)R(-)] undergoing routine testing for CMV replication as part of a preemptive strategy. We compared CMV-specific interferon-γ (IFN-γ) responses of CD4+CD3+ lymphocytes in peripheral blood mononuclear cells (PBMC) using three different antigen preparation (CMV-lysate, pp72- and pp65-overlapping peptide pools) using intracellular cytokine staining and flow cytometry.ResultsMedian CD4+ and CD8+T-cell responses to CMV-lysate, pp72- and pp65-overlapping peptide pools were lower in D(+)R(-) than in R(+)patients or in non-immunosuppressed donors. Comparing subpopulations we found that CMV-lysate favored CD4+- over CD8+-responses, whereas the reverse was observed for pp72, while pp65-CD4+- and -CD8+-responses were similar. Concurrent CMV replication in R(+)-patients was associated with significantly lower T-cell responses (pp65 median CD4+ 0.00% vs. 0.03%, p = 0.001; CD8+ 0.01% vs. 0.03%; p = 0.033). Receiver operated curve analysis associated CMV-pp65 CD4+ responses of > 0.03% in R(+)-patients with absence of concurrent (p = 0.003) and future CMV replication in the following 8 weeks (p = 0.036). GCV-resistant CMV replication occurred in 3 R(+)-patients (6.3%) with pp65- CD4+ frequencies < 0.03% (p = 0.041).ConclusionThe data suggest that pp65-specific CD4+ T-cells might be useful to identify R(+)-patients at increased risk of CMV replication. Provided further corroborating evidence, CMV-pp65 CD4+ responses above 0.03% in PBMCs of KT patients under stable immunosuppression are associated with lower risk of concurrent and future CMV replication during the following 8 weeks.

Polyomavirus infections in transplant recipients

Polyomavirus infection in immunosuppressed transplant patients is in most cases an asymptomatic reactivation of a latent infection that can, however, progress to manifest disease. JC virus causes progressive multifocal leukoencephalopathy, a rare complication with poor outcome. BK virus infection has been associated with hemorrhagic cystitis of late onset in bone marrow recipients and with ureteral stenosis in renal allograft recipients. More recently, BK virus has been identified in renal transplant recipients as the cause of progressive graft dysfunction and loss. The diagnosis of BK virus nephropathy requires allograft biopsy, revealing typical viral intranuclear inclusion bodies, and, in typical cases, damage of tubules. Urine cytology and the detection of BK virus DNA in plasma helps to identify and manage patients with BK virus nephropathy. Because of the lack of effective antiviral therapy, current treatment attempts aim at lowering the degree of immunosuppression in order to regain control over polyomavirus replication.

Monitoring of cytomegalovirus infection in solid-organ transplant recipients by an ultrasensitive plasma PCR assay.

ABSTRACT Early and accurate monitoring of cytomegalovirus (CMV) infection in solid-organ transplant recipients is of major importance. We have assessed the potential benefit of an ultrasensitive plasma-based PCR assay for renal transplant recipients. The pp65 CMV antigen (pp65 Ag) assay using leukocytes was employed as a routine test for the monitoring of CMV in 23 transplant recipients. We compared the pp65 antigenemia with the CMV load quantified by an ultrasensitive PCR (US-PCR) with a limit of detection of 20 CMV DNA copies/ml of plasma. CMV infection was detected in 215 (67%) of 321 plasma samples by the US-PCR compared with 124 (39%) of 321 samples by the pp65 Ag assay. The US-PCR assay permitted the detection of CMV infection episodes following transplantation a median of 12 days earlier than the pp65 Ag assay. Moreover, during CMV infection episodes, DNA detection by the US-PCR was consistently positive, whereas false negative results were frequently observed with the pp65 Ag assay. We found a good correlation between the two assays, and the peak viral loads were significantly higher in patients with CMV-related complications (median, 5,000 DNA copies/ml) than in those without symptoms (1,160 DNA copies/ml) (P = 0.048). In addition, patients that did not require preemptive therapy based on the results of the pp65 assay had CMV loads significantly lower (median, 36 DNA copies/ml) than those that needed treatment (median, 4,703 DNA copies/ml) (P < 0.001). These observations provided cutoff levels that could be applied in clinical practice. The ultrasensitive plasma-based PCR detected CMV infection episodes earlier and provided more consistent results than the pp65 Ag assay. This test could improve the monitoring of CMV infection or reactivation in renal transplant recipients.

The specific monocarboxylate transporter (MCT1) inhibitor, AR-C117977, a novel immunosuppressant, prolongs allograft survival in the mouse.

Novel small molecular weight compounds that act by inhibiting the monocarboxylate transporter (MCT1) receptor have been found to cause profound inhibition of T-cell responses to alloantigen in vitro. Here, we have investigated the ability of one compound in this series, AR-C117977, a potent MCT1 inhibitor, to prevent the acute and chronic rejection of vascularized and nonvascularized allografts in the mouse. Treatment with AR-C117977 or cyclosporin A (CsA) administered at a dose of 30 mg/kg subcutaneously for 15 days to adult CBA. Ca (H2k) mice, commencing either 3 days or 1 day before transplantation, was found to prolong the survival of an allogeneic (C57BL/10 H2b; NZW H2z; or BALB/c H2d) heart, aorta, or skin allograft significantly compared with treatment with vehicle alone (median survival time [MST] AR-C117977 treated 15; 19 and 18 days [skin] and 73; 66 and 67 days ([heart] vs. vehicle treated 8, 8 and 9 days [skin] and 9, 8, 10 days [heart] for B10, NZW and BALB grafts, respectively). AR-C117977 also inhibited the development of transplant arteriosclerosis in aortic allografts partially, but was unable to inhibit alloantibody production after transplantation. The specific MCT1 inhibitor AR-C117977 has potent immunosuppressive properties in vivo effectively preventing acute but not chronic allograft rejection in the mouse.

IL1B and DEFB1 Polymorphisms Increase Susceptibility to Invasive Mold Infection After Solid Organ Transplantation

BACKGROUND Single-nucleotide polymorphisms (SNPs) in immune genes have been associated with susceptibility to invasive mold infection (IMI) among hematopoietic stem cell but not solid-organ transplant (SOT) recipients. METHODS Twenty-four SNPs from systematically selected genes were genotyped among 1101 SOT recipients (715 kidney transplant recipients, 190 liver transplant recipients, 102 lung transplant recipients, 79 heart transplant recipients, and 15 recipients of other transplants) from the Swiss Transplant Cohort Study. Association between SNPs and the end point were assessed by log-rank test and Cox regression models. Cytokine production upon Aspergillus stimulation was measured by enzyme-linked immunosorbent assay in peripheral blood mononuclear cells (PBMCs) from healthy volunteers and correlated with relevant genotypes. RESULTS Mold colonization (n = 45) and proven/probable IMI (n = 26) were associated with polymorphisms in the genes encoding interleukin 1β (IL1B; rs16944; recessive mode, P = .001 for colonization and P = .00005 for IMI, by the log-rank test), interleukin 1 receptor antagonist (IL1RN; rs419598; P = .01 and P = .02, respectively), and β-defensin 1 (DEFB1; rs1800972; P = .001 and P = .0002, respectively). The associations with IL1B and DEFB1 remained significant in a multivariate regression model (P = .002 for IL1B rs16944; P = .01 for DEFB1 rs1800972). The presence of 2 copies of the rare allele of rs16944 or rs419598 was associated with reduced Aspergillus-induced interleukin 1β and tumor necrosis factor α secretion by PBMCs. CONCLUSIONS Functional polymorphisms in IL1B and DEFB1 influence susceptibility to mold infection in SOT recipients. This observation may contribute to individual risk stratification.

Influence of IFNL3/4 Polymorphisms on the Incidence of Cytomegalovirus Infection After Solid-Organ Transplantation

BACKGROUND Polymorphisms in IFNL3 and IFNL4, the genes encoding interferon λ3 and interferon λ4, respectively, have been associated with reduced hepatitis C virus clearance. We explored the role of such polymorphisms on the incidence of cytomegalovirus (CMV) infection in solid-organ transplant recipients. METHODS White patients participating in the Swiss Transplant Cohort Study in 2008-2011 were included. A novel functional TT/-G polymorphism (rs368234815) in the CpG region upstream of IFNL3 was investigated. RESULTS A total of 840 solid-organ transplant recipients at risk for CMV infection were included, among whom 373 (44%) received antiviral prophylaxis. The 12-month cumulative incidence of CMV replication and disease were 0.44 and 0.08 cases, respectively. Patient homozygous for the minor rs368234815 allele (-G/-G) tended to have a higher cumulative incidence of CMV replication (subdistribution hazard ratio [SHR], 1.30 [95% confidence interval {CI}, .97-1.74]; P = .07), compared with other patients (TT/TT or TT/-G). The association was significant among patients followed by a preemptive approach (SHR, 1.46 [95% CI, 1.01-2.12]; P = .047), especially in patients receiving an organ from a seropositive donor (SHR, 1.92 [95% CI, 1.30-2.85]; P = .001), but not among those who received antiviral prophylaxis (SHR, 1.13 [95% CI, .70-1.83]; P = .6). These associations remained significant in multivariate competing risk regression models. CONCLUSIONS Polymorphisms in the IFNL3/4 region influence susceptibility to CMV replication in solid-organ transplant recipients, particularly in patients not receiving antiviral prophylaxis.

Polymorphisms in the lectin pathway of complement activation influence the incidence of acute rejection and graft outcome after kidney transplantation

There are conflicting data on the role of the lectin pathway of complement activation and its recognition molecules in acute rejection and outcome after transplantation. To help resolve this we analyzed polymorphisms and serum levels of lectin pathway components in 710 consecutive kidney transplant recipients enrolled in the nationwide Swiss Transplant Cohort Study, together with all biopsy-proven rejection episodes and 1-year graft and patient survival. Functional mannose-binding lectin (MBL) levels were determined in serum samples, and previously described MBL2, ficolin 2, and MBL-associated serine protease 2 polymorphisms were genotyped. Low MBL serum levels and deficient MBL2 diplotypes were associated with a higher incidence of acute cellular rejection during the first year, in particular in recipients of deceased-donor kidneys. This association remained significant (hazard ratio 1.75, 95% confidence interval 1.18-2.60) in a Cox regression model after adjustment for relevant covariates. In contrast, there was no significant association with rates of antibody-mediated rejection, patient death, early graft dysfunction or loss. Thus, results in a prospective multicenter contemporary cohort suggest that MBL2 polymorphisms result in low MBL serum levels and are associated with acute cellular rejection after kidney transplantation. Since MBL deficiency is a relatively frequent trait in the normal population, our findings may lead to individual risk stratification and customized immunosuppression.