Effect of increasing baseline immunosuppression on the prevalence of clinical and subclinical rejection: a pilot study

Natural History, Risk Factors, and Impact of Subclinical Rejection in Kidney Transplantation

BACKGROUND

Subclinical rejection (SCR) is defined as histologically proven acute rejection in the absence of immediate functional deterioration.

METHODS

We evaluated the impact of SCR in 961 prospective protocol kidney biopsies from diabetic recipients of a kidney-pancreas transplant (n=119) and one kidney transplant alone taken regularly up to 10 years after transplantation.

RESULTS

SCR was present in 60.8%, 45.7%, 25.8%, and 17.7% of biopsies at 1, 3, 12, and greater than 12 months after transplantation. Banff scores for acute interstitial inflammation and tubulitis declined exponentially with time. SCR was predicted by prior acute cellular rejection and type of immunosuppressive therapy (P<0.05-0.001). Tacrolimus reduced interstitial infiltration (P<0.001), whereas mycophenolate reduced tubulitis (P<0.05), and the combination effectively eliminated SCR (P<0.001). Persistent SCR of less than 2 years duration on sequential biopsies occurred in 29.2% of patients and was associated with prior acute interstitial rejection (P<0.001) and requirement for antilymphocyte therapy (P<0.05). It resolved by 0.49 +/- 0.33 years and resulted in higher grades of chronic allograft nephropathy (CAN, P<0.05). True chronic rejection, defined as persistent SCR of 2 years or more duration and implying continuous immunologic activation was found in only 5.8% of patients. The presence of SCR increased chronic interstitial fibrosis, tubular atrophy, and CAN scores on subsequent biopsies (P<0.05-0.001). SCR preceded and was correlated with CAN (P<0.001) on sequential analysis.

CONCLUSIONS

Histologic evidence of acute rejection in the absence of clinical suspicion resulted in significant tubulointerstitial damage to transplanted kidneys and contributed to CAN.

Subclinical rejection and borderline changes in early protocol biopsy specimens after renal transplantation

BACKGROUND

To determine the significance of early subclinical rejection, we reviewed protocol biopsies performed on days 7 and 28 during a 4-year period.

METHODS

The study was confined to patients (n=115) with stable graft function at the time of biopsy; 76 adequate biopsies at day 7 and 79 at day 28 were performed.

RESULTS

At day 7, 10 biopsy specimens (13%) showed acute rejection (AR) and 9 (12%) showed borderline changes. Eight of 10 patients with AR received immediate pulsed methylprednisolone (MP) and one untreated patient developed clinical rejection (CR) within 3 days. Four of nine patients whose biopsy specimens showed borderline changes received MP and three untreated patients developed CR within 3 days. At day 28, six biopsy specimens (8%) showed AR and 13 (16%) showed borderline changes. Three of six patients with AR received immediate pulsed MP and one untreated patient developed CR within 6 days. Ten of 13 patients with borderline changes had been treated for AR in the previous 3 weeks. Twelve patients with subclinical rejection or borderline changes at day 28 were never subsequently treated for rejection, and outcome at 6 years did not differ from those patients whose biopsy specimens showed no rejection.

CONCLUSIONS

Compared with some units, the incidence of subclinical rejection is low. The majority of untreated subclinical borderline changes and rejection at day 7 behaved as early clinical rejections and at day 28 as resolving clinical rejections. Untreated subclinical rejection or borderline change at day 28 was not an adverse prognostic factor for long-term outcome.

Molecular markers in subclinical acute rejection of renal transplants

In this study, we evaluated the expression of molecular markers of acute rejection in protocol biopsies of patients with and without subclinical acute rejection (SAR). Protocol biopsies were performed at 2 months (n = 21) and 12 months (n = 14) after kidney transplantation in patients with stable allograft function. After biopsy tissue RNA isolation, reverse transcription and polymerase chain reaction (RT-PCR) for the glyceraldehyde 3-phospate dehydrogenase (GAPDH), perforin, granzyme B and Fas ligand genes were performed. The Banff 97 classification was used for histological diagnosis. Creatinine concentrations at 2 months were significantly higher in patients with SAR (1.46 +/- 0.27 x 1.18 +/- 0.24; p < 0.02). Perforin transcripts were found in 15 biopsy specimens, 10 of which had histological signs of SAR (p = 0.06). Granzyme B expression was found in 10 specimens, nine of which had SAR (p < 0.01). Fas ligand was expressed in seven specimens, and six of them were classified as SAR (p < 0.01). Perforin expression had the highest sensitivity (81%) for the diagnosis of SAR. Granzyme B and Fas ligand had specificity of 90%. At 12 months, there was no significant difference in creatinine concentrations for patients with and without previous SAR (1.63 +/- 0.57 x 1.28 +/- 0.31; p = 0.10). Molecular analysis revealed that there was no statistically significant difference in the expression of perforin and granzyme B in patients with and without SAR. Fas ligand expression was observed in five samples, four of which had histological signs of SAR (p = 0.03). At 12 months, perforin expression had the highest sensitivity (83%), and Fas ligand, the highest specificity (88%) for the diagnosis of SAR. We concluded that the expression of genes that encode proteins involved in the cytolytic attack against the allograft is increased in kidneys with SAR. These findings support the understanding that SAR is an active immune process potentially deleterious to renal allografts.

Current status of kidney transplant: update 2003

Pediatric transplantation has seen remarkable advances over the past two decades with reduced morbidity and mortality, reduced rejection rates, and improved long-term patient and allograft survival. Infants currently have short-term patient and allograft survival rates better than any other age group; short-term allograft survival rates in CD recipients are equal to those in LD recipients. With decreased rejection, long-term allograft survival is improving dramatically. Transplantation allows for much reduced risks and improved metabolic status, growth and development, and more normal social interactions. The future of transplantation continues to be exciting, with opportunities for reduced immunosuppressive medications and their side effects, and the elusive goal of transplantation tolerance seems within reach.

Effect of mycophenolate mofetil regimen on peripheral blood lymphocyte subsets in kidney transplant recipients

BACKGROUND AND AIMS

There is growing evidence of the effects of immunosuppressive agents on "immune targets" in renal transplantation. Immunological monitoring could indirectly measure the suppressive effect of these drugs and guide early preventive interventions in transplant recipients. Due to the selective antiproliferative effect of mycophenolate mofetil (MMF) on lymphocytes, our goal was to determine whether MMF modulates peripheral blood lymphocyte subsets (PBLS) in kidney allograft patients.

METHODS

We assessed absolute CD3(+), CD3(+)CD4(+), CD3(+)CD8(+), CD19(+), CD16(+)CD3(-) PBLS counts and CD4/CD8 ratios for 12 months in three groups of kidney allograft patients stratified according to maintenance immunosuppressive regimen: group A (n = 31), which started MMF with prednisone (P) + cyclosporine A (CyA), and two control groups, B (n = 19) and C (n = 15) on P + CyA + azathioprine (Aza) and P + CyA regimens, respectively. We compared intra- and intergroup lymphocyte counts and ratios.

RESULTS

Intergroup comparisons showed a significant reduction in all PBLS in group A (CD19(+) from 3 months and other subsets from 6 months), whereas there were no significant changes in PBLS in the other group analyses or comparisons.

CONCLUSIONS

Our findings suggest that (1) MMF modulates all PBLS in kidney allograft patients, causing a progressive reduction occurring earlier in CD19(+), and (2) we can rule out that these changes were caused by the "natural immunological evolution" of the transplantation. These results could offer a new method for immunological monitoring of transplant patients.

Analysis of allograft biopsy specimens from long-term surviving patients with stable renal function: predictive value of long-term graft prognosis

Chronic allograft dysfunction is multi-factorial, and histology of long-term renal allograft shows variable findings. It is important to characterize the pathological features of graft kidneys with normal function to understand the natural course of transplants, which in turn would contribute to elucidate the causes of chronic allograft nephropathy (CAN). To address this issue, we performed 'non-episode' biopsies on well-functioning renal allografts, and evaluated the correlation between clinical outcome and histopathological findings. Patients who underwent a non-episode biopsy had a serum creatinine concentration less than 2.0 mg/dL, urinary protein of less than 500 mg/day and a stable clinical course. In total, 90 such biopsies were performed. Mean follow-up period after biopsy was 29 +/- 16 months. We evaluated the histopathological findings and clinical outcome on each finding. Moreover, we compared the findings in the patients on tacrolimus with those of patients taking cyclosporin. Twenty-three biopsy specimens were essentially normal. Graft dysfunction during the follow-up period was recognized more frequently in patients showing more than one pathological process than in those with isolated findings. Graft outcome was not associated with drug-induced nephropathy, but with acute rejection (P = 0.0193) and CAN (P = 0.0032). Patients found to have CAN-b had a worse outcome than those with CAN-a. CAN-b was less common in the tacrolimus group than in the cyclosporin group. Non-episode biopsy has a predictive value of the long-term outcome of a renal allograft. CAN is associated with graft dysfunction; neither is drug-induced nephropathy. Patients treated with tacrolimus had lower rates of CAN-b than did cyclosporin-treated subjects.

The impact of repeated subclinical acute rejection on the progression of chronic allograft nephropathy

Chronic allograft nephropathy (CAN) is due to both immunologic and non-immunologic factors and results in the development of nonspecific pathologic features that may even be present in long-term well-functioning renal allografts. To investigate the natural history of CAN and potential risk factors associated with progression of these histologic lesions, this study evaluated the of histologic alterations of 124 sequential protocol biopsies performed at 2, 3, and 5 yr after transplantation in 46 patients who exhibited histologic evidence of CAN in the 1-yr biopsy. The occurrence of late acute rejection (AR) greater than 4 mo posttransplant was significantly associated with the development of histologic CAN. In contrast, early clinical AR occurring within 3 mo had no impact on the subsequent development of CAN at 1 yr. Subclinical AR was evident in association with CAN in 50%, 32%, 19%, and 16% of cases with CAN at 1, 2, 3, and 5 yr, respectively. These acute lesions correlated significantly with histologic progression defined as an increased CADI score of the follow-up biopsies. Furthermore, a group of patients who exhibited repeated subclinical AR in the sequential follow-up biopsies had a lower creatinine clearance at 5 yr after transplantation and worse long-term graft survival. In contrast, the absence of evidence of acute inflammation in association with CAN at any time point was associated with minimal deterioration in renal function or progression of renal lesions during the observation period. These results suggest that the persistence of chronic active inflammation may be responsible for the histologic progression of CAN.

Subclinical rejection in tacrolimus-treated renal transplant recipients

BACKGROUND

Subclinical rejection, defined as histologic acute rejection in the absence of graft dysfunction, has been suggested as a cause of chronic allograft rejection. In cyclosporine-treated patients, the incidence of subclinical rejection 3 months after transplant is reported to be approximately 30%. The intent of our study was to determine the incidence of subclinical rejection in tacrolimus-treated renal allograft recipients.

METHODS

We prospectively studied the incidence of subclinical rejection on surveillance biopsies performed 3 months after transplantation in 114 patients transplanted between September 1, 1998 and November 30, 2000. All patients received tacrolimus, mycophenolate mofetil, and prednisone, and 56% received antibody induction.

RESULTS

Subclinical rejection was detected in 2.6% of patients (3/114, 95% confidence interval 0.5-7.5%). Borderline changes were detected in 11% (12/114). Subclinical rejections were treated with bolus methylprednisolone.

CONCLUSIONS

The incidence of subclinical rejection early after kidney transplantation is extremely low in tacrolimus-treated patients in whom early rejections are aggressively treated, suggesting that surveillance biopsies may not be necessary with this regimen.

Loss of direct and maintenance of indirect alloresponses in renal allograft recipients: implications for the pathogenesis of chronic allograft nephropathy

Chronic allograft nephropathy (CAN) is the principal cause of late renal allograft failure. This complex process is multifactorial in origin, and there is good evidence for immune-mediated effects. The immune contribution to this process is directed by CD4(+) T cells, which can be activated by either direct or indirect pathways of allorecognition. For the first time, these pathways have been simultaneously compared in a cohort of 22 longstanding renal allograft recipients (13 with good function and nine with CAN). CD4(+) T cells from all patients reveal donor-specific hyporesponsiveness by the direct pathway according to proliferation or the secretion of the cytokines IL-2, IL-5, and IFN-gamma. Donor-specific cytotoxic T cell responses were also attenuated. In contrast, the frequencies of indirectly alloreactive cells were maintained, patients with CAN having significantly higher frequencies of CD4(+) T cells indirectly activated by allogeneic peptides when compared with controls with good allograft function. An extensive search for alloantibodies has revealed significant titers in only a minority of patients, both with and without CAN. In summary, this study demonstrates widespread donor-specific hyporesponsiveness in directly activated CD4(+) T cells derived from longstanding recipients of renal allografts, whether they have CAN or not. However, patients with CAN have significantly higher frequencies of CD4(+) T cells activated by donor Ags in an indirect manner, a phenomenon resembling split tolerance. These findings provide an insight into the pathogenesis of CAN and also have implications for the development of a clinical tolerance assay.

Serial evaluation of cell surface markers for immune activation after acute renal allograft rejection by urine flow cytometry--correlation with clinical outcome

BACKGROUND

The use of urine flow cytometry (UFC) as a noninvasive tool for the diagnosis of acute and chronic rejection of the renal allograft has been previously reported.

METHODS

We analyzed the expression of various cell surface antigens during a 30-day period after the diagnosis and treatment of 24 acute rejection (AR) episodes. UFC was performed on 59 urine specimens, from 17 patients meeting the diagnostic criteria for AR. UFC analysis was performed blinded to the clinical management utilizing the following fluorescinated monoclonal antibodies: anti-CD3, anti-CD14, anti-HLA-DR, anti-CD54, and anti-interleukin 2 receptor. Results were correlated with the patient's requirement for antilymphocytic drugs and increment in serum creatinine level (mg/dl) on day 30 after AR.

RESULTS

HLA-DR was the most prevalent antigen noted during the first 2 days of AR (91.7% of the samples), followed by CD14 (50%) and CD54 (41.7%). After day 4 the degree of expression of HLA-DR-, CD14-, and CD54-positive cells correlated with the need for antilymphocytic drugs. CD54 was the best parameter with a sensitivity=100% and specificity=90.9% (P=0.001). Those patients who had permanent graft injury after treatment of the AR had persistence of CD54- and CD14-positive cells in the urine.

CONCLUSION

Serial monitoring of urine sediments by UFC was predictive of the requirement for antilymphocytic therapy and irreversible graft damage.

Long-term allograft surveillance: the role of protocol biopsies

The safety of the renal allograft biopsy and the standardization of allograft histopathology interpretation have renewed interest in the performance of protocol (surveillance) biopsies. Recent surveillance biopsy studies in the areas of pre-implantation and in the early and late post-transplant periods are discussed.

Recommendations for the outpatient surveillance of renal transplant recipients. American Society of Transplantation

Many complications after renal transplantation can be prevented if they are detected early. Guidelines have been developed for the prevention of diseases in the general population, but there are no comprehensive guidelines for the prevention of diseases and complications after renal transplantation. Therefore, the Clinical Practice Guidelines Committee of the American Society of Transplantation developed these guidelines to help physicians and other health care workers provide optimal care for renal transplant recipients. The guidelines are also intended to indirectly help patients receive the access to care that they need to ensure long-term allograft survival, by attempting to systematically define what that care encompasses. The guidelines are applicable to all adult and pediatric renal transplant recipients, and they cover the outpatient screening for and prevention of diseases and complications that commonly occur after renal transplantation. They do not cover the diagnosis and treatment of diseases and complications after they become manifest, and they do not cover the pretransplant evaluation of renal transplant candidates. The guidelines are comprehensive, but they do not pretend to cover every aspect of care. As much as possible, the guidelines are evidence-based, and each recommendation has been given a subjective grade to indicate the strength of evidence that supports the recommendation. It is hoped that these guidelines will provide a framework for additional discussion and research that will improve the care of renal transplant recipients.

Long-term outcomes of renal transplantation: a result of the original endowment of the donor kidney and the inflammatory response to both alloantigens and injury

Recent data suggest that long-term allograft survival might be affected by two factors. The first is the endowment of the allograft, which consists of two elements: the nephron mass and the ability of these nephrons to repair injuries sustained during the transplant process. The second factor is renal inflammation. Although inflammation is traditionally ascribed to alloreactivity, recent data have shown that there is also a renal inflammatory response to early injury after transplantation, to brain death in the donor, and as part of the maladaptive response to nephron loss. These two factors contribute to the detrimental effects of delayed graft function or acute rejection on the long-term survival seen in most studies, and the beneficial effects of anti-inflammatory agents on the maladaptive response to nephron loss.

Protocol biopsies in the management of renal allograft recipients

The safety of the renal allograft biopsy and the standardization of allograft histopathology interpretation have renewed interest in the protocol biopsy. Recent studies in the areas of 'marginal' donors, surveillance of acute rejection, molecular biology and chronic rejection are discussed.

Does subclinical rejection contribute to chronic rejection in renal transplant patients?

Renal allograft biopsies have traditionally been performed in the setting of acute graft dysfunction. However, several groups have performed graft biopsies at times of stable graft function, and more recently, after treatment of rejection episodes. Surprisingly, unequivocal histologic criteria for acute rejection have been demonstrated in a high proportion of these protocol biopsies. The Winnipeg Transplant Group has documented the high prevalence of clinically silent inflammatory infiltrates in early protocol biopsies, and demonstrated their inflammatory and cytotoxic potential by immunohistochemical and molecular biological techniques. Furthermore, in a randomized trial, our group has demonstrated that subclinical rejection, if untreated, is associated with the development of early chronic pathology and late graft dysfunction. In this overview, we will summarize the early data on subclinical allograft inflammation, present the experience of the Winnipeg Transplant Group, and discuss the possible implications of subclinical rejection on the development of chronic rejection.

Diagnostic techniques in the work-up of renal allograft dysfunction--an update

After renal transplantation, acute allograft dysfunction secondary to acute rejection occurs in around 30-40% of patients. Although in the majority of patients these episodes are reversible, acute rejection remains a major risk factor for the development of chronic rejection. Remarkably, prior episodes of acute allograft rejection are associated with decreased allograft survival. Histologic examination of the percutaneous core needle transplant biopsy remains the gold standard for the diagnosis of acute rejection. It does, however, have a number of shortcomings, and less invasive procedures that could diagnose incipient rejection and simultaneously provide mechanistic information on the rejection process (allowing delivery of more tailored therapy) are being sought. To address these problems a number of alternative diagnostic procedures have been suggested, including duplex Doppler ultrasound assessment, fine-needle aspiration biopsy, urine cytology, urine cytokine analysis, serum cytokine analysis, and cytokine analysis of biopsy material.