Marta Carrera

Subclinical rejection associated with chronic allograft nephropathy in protocol biopsies as a risk factor for late graft loss

Chronic allograft nephropathy (CAN) in protocol biopsies is associated with graft loss while the association between subclinical rejection (SCR) and outcome has yielded contradictory results. We analyze the predictive value of SCR and/or CAN in protocol biopsies on death‐censored graft survival. Since 1988, a protocol biopsy was done during the first 6 months in stable grafts with serum creatinine <300 μmol/L and proteinuria <1 g/day. Biopsies were evaluated according to Banff criteria. Borderline changes and acute rejection were grouped as SCR. CAN was defined as presence of interstitial fibrosis and tubular atrophy. Mean follow‐up was 91 ± 46 months. Sufficient tissue was obtained in 435 transplants. Biopsies were classified as normal (n = 186), SCR (n = 74), CAN (n = 110) and SCR with CAN (n = 65). Presence of SCR with CAN was associated with old donors, percentage of panel reactive antibodies and presence of acute rejection before protocol biopsy. Cox regression analysis showed that SCR with CAN (relative risk [RR]: 1.86, 95% confidence interval [CI]: 1.11–3.12; p = 0.02) and hepatitis C virus (RR: 2.27, 95% CI: 1.38–3.75; p = 0.01) were independent predictors of graft survival. In protocol biopsies, the detrimental effect of interstitial fibrosis/tubular atrophy on long‐term graft survival is modulated by SCR.

Hepatitis C Virus Infection and de Novo Glomerular Lesions in Renal Allografts

In the present study we examine whether hepatitis C virus (HCV) infection status influences glomerular pathologic findings in renal allografts and its effect on graft outcome. Renal allograft biopsies performed between January 1991 and June 1999 were considered. Exclusion criteria were insufficient sample, unknown HCV serological status at time of biopsy and final diagnosis of acute rejection. Light microscopy and immunofluorescence studies were performed on all biopsies. According to a predefined protocol, electron microscopy was carried out. Of 138 eligible renal allograft biopsies, 42 fulfilled at least one exclusion criterion. Of 96 biopsies selected for the study, 44 (45.8%) were from HCV‐positive and 52 from HCV‐negative recipients. Renal biopsy was performed 74 ± 55 and 60 ± 39 months after transplantation in HCV‐positive and HCV‐negative groups, respectively (p = 0.12). Of 44 HCV‐positive biopsies, 20 (45.4%) showed membranoproliferative glomerulonephritis (MPGN) (16 type I and 4 type III). Conversely, in HCV‐negative biopsies there were only three cases of MPGN (2 type I and 1 type III). De novo membranous GN (MGN) was diagnosed in 8/44 (18.2%) HCV‐positive and in 4/52 (7.7%) HCV‐negative cases. The prevalence of chronic transplant glomerulopathy was similar in HCV‐positive and HCV‐negative groups (11.4% and 11.5%, respectively). The prognosis of de novo GN (either MPGN or MGN) was worse in HCV‐positive than in HCV‐negative recipients (relative risk 4.89; 95% confidence interval, 1.15–20.69; p = 0.03). By multivariate analysis, HCV‐positive serology infection was the only independent predictor of graft loss (relative risk 2.64; 95% confidence interval, 1.35–5.17; p = 0.005). In diagnostic renal allograft biopsies the presence of de novo immune‐mediated glomerulonephritis, especially type I MPGN, is strongly associated with HCV infection and results in accelerated loss of the graft.

Incidence of C4d Stain in Protocol Biopsies from Renal Allografts: Results from a Multicenter Trial

C4d staining of renal allografts is regarded as an in situ marker of active humoral rejection. Few data are available about the incidence of C4d deposition in protocol biopsies compared to indication biopsies. To evaluate whether center‐specific factors influence the incidence of C4d detection, we performed a multicenter study. From three European centers, 551 protocol and 377 indication biopsies were reclassified according to the updated Banff criteria and stained for C4d. C4d results were recorded as diffuse or focal positive and statistically correlated to clinical parameters, morphology and graft survival. In the protocol biopsies, a diffuse C4d stain was found in 2.0%, and a focal stain in 2.4%. In indication biopsies, 12.2% were diffusely and 8.5% focally C4d positive (protocol:indication p < 0.0001). The incidence of C4d deposition varied significantly between centers, attributable to variable numbers of presensitized patients with more C4d positive indication and protocol biopsies. Diffuse and focal C4d stain correlated with morphology of humoral rejection in protocol as well as in indication biopsies. Protocol biopsies show a significantly lower incidence of C4d deposition than indication biopsies. Subclinical C4d detection in protocol biopsies had no significant impact on allograft survival in our series.

International variation in histologic grading is large, and persistent feedback does not improve reproducibility.

Histologic grading systems are used to guide diagnosis, therapy, and audit on an international basis. The reproducibility of grading systems is usually tested within small groups of pathologists who have previously worked or trained together. This may underestimate the international variation of scoring systems. We therefore evaluated the reproducibility of an established system, the Banff classification of renal allograft pathology, throughout Europe. We also sought to improve reproducibility by providing individual feedback after each of 14 small groups of cases. Kappa values for all features studied were lower than any previously published, confirming that international variation is greater than interobserver variation as previously assessed. A prolonged attempt to improve reproducibility, using numeric or graphical feedback, failed to produce any detectable improvement. We then asked participants to grade selected photographs, to eliminate variation induced by pathologists viewing different areas of the slide. This produced improved kappa values only for some features. Improvement was influenced by the nature of the grade definitions. Definitions based on “area affected” by a process were not improved. The results indicate the danger of basing decisions on grading systems that may be applied very differently in different institutions.

Achieving Donor-Specific Hyporesponsiveness Is Associated with FOXP3+ Regulatory T Cell Recruitment in Human Renal Allograft Infiltrates

Exploring new immunosuppressive strategies inducing donor-specific hyporesponsiveness is an important challenge in transplantation. For this purpose, a careful immune monitoring and graft histology assessment is mandatory. Here, we report the results of a pilot study conducted in twenty renal transplant recipients, analyzing the immunomodulatory effects of a protocol based on induction therapy with rabbit anti-thymocyte globulin low doses, sirolimus, and mofetil mycophenolate. Evolution of donor-specific cellular and humoral alloimmune response, peripheral blood lymphocyte subsets and apoptosis was evaluated. Six-month protocol biopsies were performed to assess histological lesions and presence of FOXP3+ regulatory T cells (Tregs) in interstitial infiltrates. After transplantation, there was an early and transient apoptotic effect, mainly within the CD8+HLADR+ T cells, combined with a sustained enhancement of CD4+CD25+high lymphocytes in peripheral blood. The incidence of acute rejection was 35%, all steroid sensitive. Importantly, only pretransplant donor-specific cellular alloreactivity could discriminate patients at risk to develop acute rejection. Two thirds of the patients became donor-specific hyporesponders at 6 and 24 mo, and the achievement of this immunologic state was not abrogated by prior acute rejection episodes. Remarkably, donor-specific hyporesponders had the better renal function and less chronic renal damage. Donor-specific hyporesponsiveness was inhibited by depleting CD4+CD25+high T cells, which showed donor-Ag specificity. FOXP3+CD4+CD25+high Tregs both in peripheral blood and in renal infiltrates were higher in donor-specific hyporesponders than in nonhyporesponders, suggesting that the recruitment of Tregs in the allograft plays an important role for renal acceptance. In conclusion, reaching donor-specific hyporesponsiveness is feasible after renal transplantation and associated with Treg recruitment in the graft.

Early subclinical rejection as a risk factor for late chronic humoral rejection.

Background. Subclinical rejection and interstitial fibrosis and tubular atrophy (IF/TA) in protocol biopsies are associated with outcome. We study the relationship between histologic lesions in early protocol biopsies and histologic diagnoses in late biopsies for cause. Materials and Methods. Renal transplants with a protocol biopsy performed within the first 6 months posttransplant between 1988 and 2006 were reviewed. Biopsies were evaluated according to Banff criteria, and C4d staining was available in biopsies for cause. Results. Of the 517 renal transplants with a protocol biopsy, 109 had a subsequent biopsy for cause which showed the following histological diagnoses: chronic humoral rejection (CHR) (n=44), IF/TA (n=42), recurrence of the primary disease (n=11), de novo glomerulonephritis (n=7), T-cell-mediated rejection (n=4), and polyoma virus nephropathy (n=1). The proportion of retransplants (15.9% vs. 2.3%, P=0.058) and the prevalence of subclinical rejection were higher in patients with CHR than in patients with IF/TA (52.3% vs. 28.6%, P=0.0253). Demographic donor and recipient characteristics and clinical data at the time of protocol biopsy were not different between groups. Logistic regression analysis showed that subclinical rejection (relative risk, 2.52; 95% confidence interval, 1.1–6.3; P=0.047) but not retransplantation (relative risk, 6.7; 95% confidence interval, 0.8–58.8; P=0.085) was associated with CHR. Conclusion. Subclinical rejection in early protocol biopsies is associated with late appearance of CHR.

Mycophenolate mofetil reduces deterioration of renal function in patients with chronic allograft nephropathy. A follow-up study by the Spanish Cooperative Study Group of Chronic Allograft Nephropathy.

Background. Although studies have shown that mycophenolate mofetil (MMF) with cyclosporine (CsA) and prednisone can reduce the incidence of acute rejection and increase the half-life of the graft, the effects of MMF on established chronic allograft nephropathy (CAN) are controversial. Methods. We studied 121 patients with biopsy-proven CAN, 59 treated with CsA and prednisone and 62 treated with triple-drug therapy with azathioprine. At inclusion, each group received 2 g per day of MMF and azathioprine was stopped. Renal function was measured by the glomerular filtration rate (GFR) obtained by creatinine clearance (Cockcroft-Gault) and monitored by the slope of the GFR, adjusted using linear regression. Results. The median follow-up, after incorporation of MMF, was 36 (13–36) months, with 103 (85.1%) having a full 3-year follow-up. Before the introduction of MMF, there was progressive deterioration in renal function (GFR: 54.8±20.9 vs. 39.7±14.0 mL/min, P <0.001). After introduction of MMF, renal function remained stable (GFR: 39.7±14.0 vs. 41.3±10.8 mL/min, P =NS), with a significant change in the slope of the GFR (−0.0144 vs. +0.00045, P <0.001). In 65 patients in whom CsA blood levels remained unchanged during follow-up (148.0±65.6 vs. 154.1±58.2, P =NS), the slope of the GFR showed a reduction in loss of renal function (−0.0147 vs. −0.0001, P <0.001). Conclusions. Treatment with MMF reduced the progressive deterioration of renal function in patients with CAN, independently of the blood levels of CsA.

IgA nephropathy recurs early in the graft when assessed by protocol biopsy

BACKGROUND The recurrence of IgA nephropathy (IgAN) in the allograft is common. Factors related to IgA recurrence are unclear. The aims of this study were to determine the incidence of IgAN recurrence as assessed by protocol biopsies and to identify predictive factors for recurrence. METHODS We identified 65 protocol biopsies taken before the second year post-transplantation in patients with IgAN as primary renal disease. Diagnosis of recurrence of IgA was based on the detection of at least 1+ mesangial deposits of IgA. Pathological findings and clinical characteristics were retrospectively compared between recurrent and non-recurrent cases. RESULTS IgAN recurrence rate was 32%. Mesangial C3 was detected in 83% of recurrent cases versus 17% in non-recurrent patients (P < 0.001). Normal urinalysis was observed in 52%. Non-recurrent patients had arteriolar hyalinosis in 31% of the cases versus none in IgAN recurrence (P = 0.006). Seventy-nine per cent of cyclosporine users were free of recurrence, whereas 45% of the patients without cyclosporine experienced recurrence (P = 0.03). The odds ratio (OR) for IgAN recurrence in patients using cyclosporine was 0.3 (confidence interval 0.1-0.9). Zero HLA-DR mismatch was associated with non-recurrence (P < 0.01). The OR for IgA recurrence was 6.7 if any degree of DR mismatch was present. IgAN recurrent patients had better glomerular filtration rate, but after censoring delayed graft function, the differences disappeared. Graft loss due to IgA recurrence was only 3%. CONCLUSIONS IgAN recurrence rate was 32%. The histological diagnosis was not accompanied by abnormalities in the urinalysis in one-half of the patients. Full DR match and cyclosporine were associated with non-recurrence.

New immunosuppresor strategies in the treatment of murine lupus nephritis

Renal involvement in systemic lupus erythematosus is a common complication that significantly worsens morbidity and mortality. Although treatment with corticosteroids and cytotoxic drugs may be useful in many cases, morbidity associated with these drugs and the relapsing nature of the disease make it necessary to develop new treatment strategies. Five-month old female NZB/W F1 mice were divided into the following groups: CYP group (n = 10), cyclophosphamide (CYP) 50 mg/kg intraperitoneally every 10 days; RAPA 1 group (n = 10) oral daily sirolimus (SRL), 1 mg/kg; RAPA 12 group (n = 13), oral daily SRL, 12 mg/kg; FTY group (n = 10), oral fingolimod (FTY720), 2 mg/kg three times per week. An additional group of 13 non-treated mice were used as a control (control group). Follow-up was performed over four months. Animal survival, body weight, anti-DNA antibodies and proteinuria were determined. Kidneys were processed for conventional histology and immunofluorescence for IgG and complement. Total histological score (HS) was the sum of mesangial expansion, endocapillary proliferation glomerular deposits, extracapillary proliferation, interstitial infiltrates, tubular atrophy and interstitial fibrosis. All treated groups had lower proteinuria at the end of the follow-up with respect to the control group (P < 0.0001). Serum anti-DNA antibodies were appropriately controlled in RAPA 1 and CYP groups, but not in FTY or RAPA 12 groups. SRL and CYP arrested, and perhaps reversed almost all histological lesions. FTY720 ameliorated histological lesions but did not control mesangial expansion or interstitial infiltrates. SRL produces great improvement in murine lupus nephritis, while FTY720 seems a promising alternative if used in appropriate doses.

Long-Term Results of Biopsy-Guided Selection and Allocation of Kidneys From Older Donors in Older Recipients

In our old‐for‐old program, we discard or allocate older extended criteria donor kidneys to single (SKT) or dual kidney transplantation (DKT) depending on histological Remuzzis score in recipients older than 60 years. Here, we analyze the long‐term results of this program and try to identify independent predictors of patient and graft survival. Between December 1996 and January 2008, we performed 115 SKT and 88 DKT. Discard rate was 15%. Acute rejection incidence was higher in SKT than in DKT (22.6% vs. 11.4%, p = 0.04). Renal function was better in DKT than in SKT up to 5 years after transplantation. Surgical complications were frequent in DKT. Ten‐year cumulative graft survival was significantly lower in the SKT group (31% vs. 53%, p = 0.03). In SKT, histological score 4 provided similar graft survival than 3 or less, whereas in DKT score 4, 5 or 6 displayed similar outcome. Finally, independent predictors of graft survival were history of major adverse cardiac event and 1‐year serum creatinine, rather than SKT or DKT. In conclusion, this biopsy‐guided old‐for‐old strategy resulted in acceptable long‐term graft survival. Our results suggest that DKT should be considered for scores of 5 or 6 only.