Intragraft events preceding chronic renal allograft rejection in a modified tolerance protocol

BACKGROUND: Inbred miniature swine treated for 12 days with high-dose cyclosporine A develop tolerance to histocompatibility complex (MHC) class I-mismatched renal allografts. When this protocol was modified by adding thymectomy before transplant, all animals developed acute rejection. Thereafter, by day 100, one half developed chronic rejection (progression group) and the other half recovered (recovery group). This provides an excellent experimental model to identify the mechanisms of chronic rejection as well as the early changes that may predict chronic rejection. METHODS: We assessed the cellular infiltration, immune activation, humoral immunity, and cell- and antibody-mediated graft injury in the progression and the recovery groups. In addition, we also examined circulating donor reactive cytotoxic T lymphocyte (CTL) and antidonor antibody in both groups. RESULTS: From days 8 to 18 after transplantation, the two groups were indistinguishable. Both showed acute rejection with endarteritis (type II); had IgG and IgM deposition in glomeruli and small vessels; had an infiltrate with similar numbers of T cells, proliferating (PCNA+) and activated (interleukin-2 receptor+) cells; and had a similar degree of parenchymal cell apoptosis [in situ DNA nick-end labeling (TUNEL)+]. However, by days 30 to 60, the two groups could be distinguished by several intragraft features. The recovery group became tolerant and had diminished T-cell infiltration, activation and proliferation, and no detectable antibody deposition. The number of TUNEL+-injured parenchymal cells decreased. In contrast, the progression group showed persistent cell infiltration with activation and proliferation. Significantly prominent TUNEL+ apoptotic parenchymal cells in tubules, glomeruli, peritubular capillaries and arteries were seen from day 30 to day 100. Circulating donor reactive CTL and antidonor class I IgG were detected in the progression group at higher levels than in the recovery group from days 30 to 60. CONCLUSION: In tolerance-induction protocols, unstable tolerance induction is associated with the persistent immunologic activation that mediates immunologic destruction of graft parenchymal cells and chronic rejection. Certain of the described immunopathologic findings (activation, proliferation, apoptosis, and antibody deposition) may be useful in distinguishing the type of rejection, that is, whether the allograft will progress to chronic rejection or recovery.     

Risk factors for chronic rejection in pediatric renal transplant recipients – a single-center experience

Chronic rejection (CR) is the most common cause of graft loss beyond the 1st posttransplant year. The aim of this analysis was to identify the risk factors for the development of CR in pediatric renal transplant recipients. Between June 1984 and March 1994, 217 renal transplants were performed in children at our center. Immunosuppression included prednisone, azathioprine, cyclosporine (CsA), and prophylactic antibody. Using multivariate analysis, we studied the impact of the following variables on the development of biopsy-proven CR: age at transplant (≤5 years, >5 years), gender, race, transplant number (primary, retransplant), donor source (cadaver, living donor), donor age (<20 years, 20 – 49 years, >49 years), number of ABDR mismatches (0, 1 – 2, 3 – 4, 5 – 6), number of DR mismatches (0, 1, 2), percentage peak panel reactive antibody (PRA) (≤50%, >50%), percentage PRA at transplantation (≤50%, >50%), dialysis pretransplant, preservation time >24 h, acute tubular necrosis requiring dialysis, initial CsA dosage (≤5 mg/kg per day, >5 mg/kg per day), CsA dosage at 1 year posttransplant (≤5 mg/kg per day, >5 mg/kg per day), acute rejection (AR), number of AR episodes (ARE) (1, >1), timing of AR (≤6 months, >6 months), reversibility of AR (complete, partial), and infection [cytomegalovirus (CMV), non-CMV viral, bacterial]. Risk factors for the development of CR in pediatric renal transplant recipients were: AR (P <0.0001, odds ratio 19.4), multiple ARE (>1 vs. 1) (P <0.0001, odds ratio 30.1), and high percentage peak PRA (>50%) (P <0.03, odds ratio 3.6). Received December 21, 1995; received in revised form and accepted January 21, 1997     

Progression of kidney disease in chronic renal transplant rejection

The rate of progression of renal insufficiency was quantitated from reciprocal of serum creatinine versus time plots in patients with clinical and histologic evidence of chronic renal transplant rejection. The plots were evaluated by the breakpoint test. This method identifies breakpoints in a linear plot and compares the statistical significance of the fit provided by two intersecting lines with that of a single straight line. The breakpoint test when applied to the 22 patients with a significant linear correlation between the reciprocal of serum creatinine versus time detected a change in the slope in 20 cases (90.9%) indicating the presence of a breakpoint. The average diastolic, systolic, and mean arterial pressures before the breakpoint were significantly correlated with the value of the serum creatinine at the time of the change of the slope (r = 0.45, P less than 0.05; r = 0.58, P less than 0.01; r = 0.56, P less than 0.05, respectively) demonstrating more severe hypertension in those patients with the more severe renal dysfunction. The slope after the breakpoint was significantly correlated with the mean diastolic blood pressure values after the breakpoint (r = 0.48, P less than 0.05) with higher pressures being found in those patients with faster rates of decline in renal function. Both before and after the breakpoint occurred, the rate of progression of the renal disease, as estimated by the reciprocal of serum creatinine versus time plot, was greater when the mean diastolic blood pressure was higher than 90 mmHg. In conclusion, the vast majority of patients with proven chronic rejection progress linearly although a change in the rate of progression was frequent. Higher levels of blood pressure correlate with greater rates of progression of renal insufficiency, and a faster progression associates with a diastolic blood pressure greater than 90 mmHg.     

Effects of dietary protein in patients with chronic renal transplant rejection.

Dietary protein restriction reduces proteinuria and slows the progression of renal failure in a variety of renal diseases in native kidneys. Such beneficial effects may be mediated by the multiple renal effects of dietary protein including those on glomerular capillary hemodynamics and the renin-angiotensin system. The role of dietary protein restriction in the management of chronic renal transplant rejection is, however, unclear. This study was therefore undertaken to examine the effects of dietary protein restriction in patients with chronic rejection. Fourteen patients with biopsy proven chronic rejection, who had been on a self-selected home diet of 1.0 +/- 0.1 g protein/kg/day, were randomly assigned, using a crossover design to two 11-day periods, one on a low protein diet (0.55 g/kg/day) and the other on a high protein diet (2 g/kg/day). The effect of these diets on renal hemodynamics, proteinuria, plasma renin activity, and nutritional status was examined. The low protein diet was associated with a significant improvement in glomerular permselectivity in all patients as evidenced by a significant fall in the fractional clearance of albumin and IgG and reduction in 24-hour urinary excretion of total protein, albumin and IgG without any change in blood pressure, glomerular filtration rate, or renal plasma flow. Compared to the proteinuria at the beginning of each diet, a high protein diet did not increase but a low protein diet significantly decreased the proteinuria. The low protein diet was also associated with a significant reduction in plasma renin activity, suggesting that part of the beneficial effect of protein restriction was related to the suppression of the renin-angiotensin system.(ABSTRACT TRUNCATED AT 250 WORDS)     

Randomized trial of misoprostol in patients with chronic renal transplant rejection

Abstract  Chronic vascular rejection is a major cause of long-term graft failure after renal transplantation. We investigated the effect of the addition of misoprostol (200 pg four times daily) to standard immunosuppressive therapy on the outcome of chronic rejection in a double-blind, placebo-controlled trial. Patients had to fulfill predefined histological and clinical criteria. After an entry of 40 patients into the study (22 misoprostol, 18 placebo), the inclusion of additional patients was terminated because of a high incidence of withdrawal due to adverse effects. Of the patients who used their study medication for at least 3 months (16 misoprostol, 15 placebo), graft function deteriorated in all but 5 misoprostol-treated and all but 2 placebo-treated patients. There was no difference in dialysis-free survival. Withdrawal because of adverse effects (mainly gastrointestinal complaints) occurred in 3 cases in the placebo group and in 11 cases in the misoprostol group ( P < 0.05). In conclusion, we found no evidence for a beneficial effect of misoprostol on the course of chronic renal allograft rejection, while use of the drug was accompanied by a high incidence of side effects.     

Microvascular destruction in renal transplant rejection

In normal kidneys, peritubular and glomerular capillaries can be readily identified by their intense expression of HLA class I and class II compared to other cells within the graft. This high density of expression of MHC, plus their exposure to activated circulating lymphocytes, makes these cells the likely early and primary target of rejection responses. The fate of these capillaries during renal allograft rejection was examined using an indirect immunoperoxidase staining technique and monoclonal antibodies to class I and class II MHC antigens as well as other antigens on capillary endothelium including ICAM-1, LFA-3, and a novel antigen identified by E1.5. Expression of HLA-DR by peritubular capillaries was decreased during rejection, and this disappearance of peritubular capillaries with severe rejection was confirmed by loss of other markers of microvascular endothelium. These studies suggest peritubular capillaries may be the major target of the acute rejection response, and the techniques described allow assessment of degree of damage to these structures in renal allograft biopsies.     

Diagnosis of renal transplant rejection

Summary A review of renal transplant rejection diagnosis is given. The immunological and morphological findings and the clinical presentation of hyperacute, acute, and chronic rejection are described. The indication, value, and limitations of diagnostic techniques such as core biopsy, immunohistology, fine-needle aspiration biopsy, T-cell subset analyses, and circulating immune complexes are analyzed. In particular, the differentiation between acute rejection and viral infection is pointed out as reflected by our own experience with in situ hybridization techniques.     

肾移植术后血清抗MICA抗体与慢性排斥反应的相关性

Objective To explore the relationship of serum anti-MICA antibody and development of chronic rejection (CR) after renal transplantation. Methods The enrolled 105 patients included 43 cases of CR, and 62 cases of functioning renal allograft as controls. Data including PRA level before transplantation, HLA mismatch, cold ischemic time, SCr at discharge, immunosuppressive regimen,and months after transplantation were analyzed. Blood samples were collected immediately after grouping for anti-MICA antibodies, SCr determination. Acute rejection episodes and renal allograft function which was evaluated by △SCr/M [(SCr at present - SCr at discharge) /months after transplantation) were compared between anti-MICA-antibody positive patients and anti-MICA-antibody negative patients. Results There was no significant difference in gender, age, HLA mismatch, cold ischemic time, immunosuppressive regimen, SCr at discharge, months after transplantation between CR and control groups (P＞0.05). Serum creatinine level and number of antiMICA-antibody positive patients in CR group were significantly increased as compared with those in control group (P＜0.01 ). Acute rejection episodes during the first 3 months after transplantation in anti-MICA-antibody positive patients were significantly more than those in anti-MICA-antibody negative patients (P＜0.05),and the △SCr/M in the former was higher than that in the latter (8.3 +3.6 vs 2.4 ± 2.6, P＜0.05). Conclusion Humoral immunoreaction mediated by MICA partly participates the development of CR after renal transplantation. MICA antibody is a risk factor affecting long-term allograft function.     

Campath and renal transplant rejection

No clear guidelines exist for the treatment of acute vascular rejection following renal transplantation. This report documents one patient who was treated with plasmapheresis, immunoglobulin and Campath with good initial response. However, rejection recurred resulting in graft loss and, in addition, the patient developed post-transplant lymphoma.     

Virus infections and acute renal transplant rejection.

The date of onset of 360 acute renal transplant rejection episodes from 1969 to 1973 have been compared with the prevalence of various common viral infections and infections due to Mycoplasma pnuemoniae. A positive correlation was found for influenza B infections (r=0.43, p less than 0.01) up to 5 months before transplantation and for adenovirus infections (r=0.32, p less than 0.05) at 1 month before kidney grafting.     

肾移植术后血清抗MICA抗体与慢性排斥反应的相关性

Objective To explore the relationship of serum anti-MICA antibody and development of chronic rejection (CR) after renal transplantation. Methods The enrolled 105 patients included 43 cases of CR, and 62 cases of functioning renal allograft as controls. Data including PRA level before transplantation, HLA mismatch, cold ischemic time, SCr at discharge, immunosuppressive regimen,and months after transplantation were analyzed. Blood samples were collected immediately after grouping for anti-MICA antibodies, SCr determination. Acute rejection episodes and renal allograft function which was evaluated by △SCr/M [(SCr at present - SCr at discharge) /months after transplantation) were compared between anti-MICA-antibody positive patients and anti-MICA-antibody negative patients. Results There was no significant difference in gender, age, HLA mismatch, cold ischemic time, immunosuppressive regimen, SCr at discharge, months after transplantation between CR and control groups (P＞0.05). Serum creatinine level and number of antiMICA-antibody positive patients in CR group were significantly increased as compared with those in control group (P＜0.01 ). Acute rejection episodes during the first 3 months after transplantation in anti-MICA-antibody positive patients were significantly more than those in anti-MICA-antibody negative patients (P＜0.05),and the △SCr/M in the former was higher than that in the latter (8.3 +3.6 vs 2.4 ± 2.6, P＜0.05). Conclusion Humoral immunoreaction mediated by MICA partly participates the development of CR after renal transplantation. MICA antibody is a risk factor affecting long-term allograft function.     

肾移植术后血清抗MICA抗体与慢性排斥反应的相关性

目的 探讨肾移植受者的抗MICA抗体水平与慢性排斥反应的相关性及其对移植肾功能的影响.方法 共有105例受者被作为研究对象纳入分析,其中发生慢性排斥反应者(慢排组)43例,移植肾功能正常者(对照组)62例.记录两组受者术前群体反应性抗体(PRA)、HLA抗原错配数、供肾冷缺血时间、出院时血清肌酐(SCr)水平、术后免疫抑制方案以及入组时间(入组时距肾移植手术时间)等资料,并进行比较.受者分组后,抽取受者外周血,检测SCr及抗MICA抗体水平,抗MICA抗体的检测采用Luminex 100免疫磁珠流式细胞仪技术.观察与比较抗MICA抗体阳性受者和抗MICA抗体阴性受者间术后3个月内发生急性排斥反应(AR)的次数和移植肾功能的差异.移植肾功能的评价采用血清肌酐变化率(△SCr/M),即(入组时SCr值-出院时SCr值)/入组时间.结果 两组受者在性别、年龄、HLA抗原错配数、供肾冷缺血时间、术后免疫抑制方案、出院时SCr水平及入组时间的比较,差异均无统计学意义(P＞0.05).分组后,慢排组受者SCr水平和抗MICA抗体阳性受者比例均明显高于对照组,两组比较,差别均有统计学意义(P＜0.01,表1).抗MICA抗体阳性受者术后3个月内发生的AR次数明显多于抗MICA抗体阴性受者,二者比较,差异有统计学意义(P＜0.05).抗MICA抗体阳性受者的△SCr/M为8.3±3.6,明显高于抗MICA抗体阴性受者的2.4±2.6,二者比较,差异有统计学意义(P＜0.05).结论 抗MICA抗体的表达与慢性排斥反应的发生相关,移植前进行MICA配型可减少术后移植肾慢性排斥反应的发生,有助于延长移植肾的长期存活.     

Adverse effects of mycophenolate mofetil in pediatric renal transplant recipients with presumed chronic rejection.

BACKGROUND: Mycophenolate mofetil (MMF) has been shown to be superior to azathioprine in reducing the incidence of acute rejection in adult renal transplant recipients. Although MMF is also being widely used in pediatric transplant patients, data documenting its safety are limited. METHODS: A retrospective review of the transplant records at St. Christopher's Hospital for Children was conducted to identify patients who had received MMF. RESULTS: Twenty-four children were switched from azathioprine to MMF, 4.8+/-2.9 years after transplantation. After an additional 0.8+/-0.4 years, MMF had been discontinued in 13 patients (54%) because of adverse effects (AE). The only variable that predicted the development of AE was a lower calculated creatinine clearance at the time of initiation of MMF. CONCLUSIONS: In pediatric renal transplant recipients with impaired renal function, the use of MMF at the recommended dose is associated with an unacceptably high incidence of AE; in such patients, the MMF dose may require modification for the level of renal function.     

Risk factors for chronic rejection in pediatric renal allograft recipients

To determine the risk factors predictive of graft loss from chronic rejection in pediatric renal allograft recipients, we reviewed the collaborative study database of the Société de Néphrologie Pédiatrique which registered 314 grafts from January 1987 to December 1991. Of the 289 grafts analyzed, 71 failed during follow-up, chronic rejection being the most common cause of graft loss (35%). The clinical features of the chronic rejection group (n = 25) were compared with those of the group without failure (n = 218). The variables tested by monovariate analysis were cyclosporine dose at 1 year, donor type, donor and recipient age, and acute rejection episodes. The incidence of graft loss due to chronic rejection was 4% (4/109) in patients who had no acute rejection and 16% (21/134) in those with at least one acute rejection episode (P = 0.002). Donor age (≤5 years) was a risk factor for chronic rejection (P = 0.024). Recipient age and donor type were not significantly different between the chronic rejection group and the control group. Using time-dependent covariates, the risk factors were an acute rejection episode (P = 0.003) and low cyclosporine doses at 1 year (P = 0.02). We conclude that acute rejection and low cyclosporine doses in these pediatric patients were risk factors for graft loss due to chronic rejection. Received 3 April 1995; received in revised form 28 December 1995; accepted 22 March 1996     

Delayed acute rejection episodes in cyclosporine-treated renal transplant recipients.

Of 109 cyclosporine-treated cadaveric renal allograft recipients, 45 were free of acute rejection in the first 4 weeks after transplantation. Eleven of 45 (24%) subsequently had delayed, biopsy-proven first rejection episodes 34-61 days after grafting, often after discharge from the hospital. Delayed rejectors had significantly higher plasma creatinine levels at all times during the first posttransplant month than 34 nonrejectors. Trough serum cyclosporine levels were similar in the two groups, although by the 4th week oral cyclosporine dose was significantly lower in the delayed rejection group. Two-thirds of those patients who had serum creatinine levels greater than or equal to 260 mumol/l at 2 weeks and greater than or equal to 225 mumol/l at 3 weeks had a delayed acute rejection episode. Renal transplant recipients treated with cyclosporine who have serum creatinine levels at or above these levels should be aggressively worked up and closely followed for the development of delayed acute rejection.     

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.     

Urine fibrin degradation products in detection and management of acute and chronic renal transplant rejection.

Detection of rejection by serial determinations of urine FDP using the latex agglutination slide test proved to be a reliable, simple and inexpensive method. In the absence of infection, clinical and biochemical acute rejection was preceded by a two-titer rise in excretion of urine FDP in 80% of 26 patients studied. It was not useful in predicting rejection in 44 stable long-term allograft recipients, although persistent elevation of urine FDP after anti-rejection therapy in these patients or those in the immediate post-transplant period implies ongoing rejection. Maintenance immunosuppression should be continued in these patients, but repeated high-dose steroid therapy should be limited because of their poor-term prognosis. Persistent increase in urine FDP may allow selection of those patients who would benefit from a trial of anticoagulant or antiplatelet therapy.