Higher Risk Of Acute Rejection Research Articles

Failure to down-regulate intragraft cytokine mRNA expression shortly after clinical heart transplantation is associated with high incidence of acute rejection

Background: Brain-death, ischemia and reperfusion damage have been implicated as initial factors that lead to a cascade of immunologic events that result in allograft rejection in experimental animals. Cytokines are thought to play a central role in this process. Therefore, we evaluated intragraft cytokine mRNA expression at an early stage after clinical heart transplantation and related these data to ischemia, immunosuppression, and rejection. Methods We sampled endomyocardial biopsies at 30 minutes (EMB 0) and at 1 week (EMB 1) after transplantation from 20 cardiac allograft recipients. Intragraft monocyte chemoattractant protein (MCP-1) and basic fibroblast growth factor (bFGF) mRNA expression levels were quantitatively measured using competitive template Reverse-transcriptase polymerase chain reaction (RT-PCR). Results We measured significantly lower MCP-1 and bFGF mRNA expression levels in EMB 1 compared with EMB 0 (MCP-1, p = 0.006; bFGF, p = 0.019). We found no direct correlation between the cytokine mRNA expression levels in EMB 0 or EMB 1 and ischemic times, induction therapy, or cyclosporine whole-blood trough levels. Patients with a high incidence of acute rejection episodes (>2 in the first year) had higher bFGF mRNA expression levels ( p = 0.009) and comparable MCP-1 mRNA expression levels ( p = 0.378) at 1 week, compared with patients with a lower rejection incidence. The MCP-1 and bFGF mRNA expression levels in the first week were not associated with the development of graft vascular disease in the first year post-transplant. Conclusions We found a significant decrease of intragraft MCP-1 and bFGF mRNA expression levels in the first post-operative week. Patients with a high incidence of acute rejection had higher bFGF mRNA expression levels in their first week biopsy. Therefore, we conclude that patients who fail to down-regulate their bFGF mRNA expression early after transplantation are at higher risk for acute rejection.

Gender differences in the risk for chronic renal allograft failure.

Despite the known differences in immunological reactivity between males and females, no differences in graft survival have been described among renal transplant recipients with regard to gender. To address this paradox, we analyzed data from 73,477 primary renal transplants collected in the US Renal Data System database. Logistic regression and Cox proportional hazard models were used to investigate the primary study end points, graft loss secondary to acute rejection (AR) or chronic allograft failure (CAF). CAF was defined as graft loss beyond 6 months, not attributable to death, recurrent disease, acute rejection, thrombosis, infection, noncompliance, or technical problems. The models adjusted for 15 covariates including immunosuppressive regimen, and donor and recipient characteristics. The overall 8-year graft and patient survivals were significantly better in female renal transplant recipients compared with male recipients. However graft survival censored for death was not significantly different by gender. By multivariate analysis, females had a 10% increased odds of AR (OR=1.10, CI 1.02-1.12), but conversely a 10% lower risk of graft loss secondary to CAF (RR=0.9, CI 0.85-0.96). The risk for CAF increased significantly with increasing age for both males and females, but this effect was greater for males than for females (P<0.001). Although female renal transplant recipients have a similar death censored graft survival compared with males, there are important differences in immunological behavior. Females have a higher risk of AR while having a decreased risk of graft loss secondary to CAF.

Donor cytokine genotype influences the development of acute rejection after renal transplantation.

Acute allograft rejection remains an important cause of morbidity after kidney transplantation, and has been shown to be a crucial determinant of long-term graft function. Although rejection is mediated by recipient lymphocytes, both donor and recipient factors contribute to the local environment that influences the nature, severity, and duration of the rejection response. Cytokines are a major determinant of this milieu, and this study sought to explore the impact of donor cytokine and cytokine receptor gene polymorphisms on acute rejection after renal transplantation. A total of 145 cadaveric renal allograft donors were selected for analysis according to the presence or absence of graft rejection in the first 30 days after transplantation. DNA was genotyped for 20 polymorphisms in 11 cytokine and cytokine receptor genes using the polymerase chain reaction with sequence specific primers. Associations were assessed using contingency table analysis and the chi2 test, using a two-set design. A polymorphism at position -174 of the donor IL-6 gene was associated with the incidence (P=0.0002) and severity (P=0.000007) of recipient acute rejection. This finding was independent of HLA-DR matching. Acute rejection was not influenced by recipient IL-6 genotype, or by donor-recipient matching of IL-6 genotype. This study identifies donor IL-6 genotype as a major genetic risk factor for the development of acute rejection after renal transplantation. This provides evidence that donor-derived cytokines play a major role in determining outcome after transplantation, and will contribute to the development of therapeutic algorithms to predict individuals at particularly high risk of acute rejection.

Failure of ganciclovir prophylaxis to completely eradicate CMV disease in renal transplant recipients treated with intense anti-rejection immunotherapy.

Ganciclovir prophylactic regimens have been shown to be effective in renal transplant recipients at risk for primary (donor seropositive/recipient seronegative) and secondary (recipient seropositive) cytomegalovirus (CMV) disease. However, in addition to serologic factors, the type and intensity of the administered immunosuppression is a strong risk factor for CMV disease. Since January 1995, we have utilized a potent immunosuppressive protocol selectively in recipients at high risk for immunologic graft loss, defined as retransplant recipients, recipients with delayed graft function, non-Caucasian recipients, and recipients suffering from acute rejection. Between January 1995 and December 1996, 110 consecutive renal transplants were performed in recipients who were either CMV seropositive or received an allograft from a CMV-seropositive donor. All recipients received ganciclovir prophylactic therapy for 3 months post-transplant. Group I (N = 43) consisted of recipients at high-immunologic risk for graft loss as defined above. These recipients were treated with an intense anti-rejection immunotherapeutic regimen consisting of Cellcept, Neoral, and prednisone, with the frequent addition of antilymphocyte antibody therapies and intravenous methylprednisolone. The remaining 67 recipients (group II) were treated with a less intense immunotherapeutic regimen consisting of azathioprine, Neoral, and prednisone. The incidence and severity of CMV disease and the patient and allograft survival were compared. The incidence of CMV syndrome was greater in group I (28%) compared with group II (7%), and was statistically significant (p < 0.05). The 1-yr patient and graft survival were similar, 95 and 91%, respectively, for group I compared with 97 and 97%, respectively, for group II. These data suggest that 3 months of ganciclovir prophylactic therapy is significantly less effective for the prevention of CMV disease in renal transplant recipients at high risk for acute rejection treated with an intense immunotherapeutic regimen. These data suggest that more effective prevention of CMV disease in these high-risk recipients will require the addition of other anti-viral agents, such as immunoglobulin preparation to the prophylactic regimen.

Steroid withdrawal in renal transplant recipients

STEROID withdrawal is one of the most controversial issues in renal transplantation. Corticosteroids are closely associated with several risk factors: hypertension, diabetes, hyperlipidemia, etc (Table 1). Nevertheless, the majority of transplant teams prefer to maintain low steroid doses to prevent chronic rejection. There are several factors that can influence the success or failure of steroid withdrawal: patient selection criteria, posttransplant interval, timing of withdrawal, concomitant immunosuppression, adequate cyclosporine (CsA) blood levels, etc. One interesting question is whether steroids can be totally avoided using CsA (or tacrolimus) as the sole induction immunosuppression therapy. There is actually substantial information in the literature showing that, despite the high rate of acute rejection, long-term graft survival rates are excellent and more than 50% of the patients can be maintained free of steroids. Another question is whether steroid withdrawal early rather than late after transplantation results in a higher rate of acute rejection. It is generally accepted that if steroids are gradually reduced, starting after 6 months posttransplantation, the risk of acute rejection remains very low. However, the new immunosuppressive drugs currently employed, like mycophenolate mofetil (MMF) or tacrolimus, offer excellent opportunities to try new strategies of steroid withdrawal. For example, excellent results have been obtained using tacrolimus in combination with MMF despite cessation of corticosteroid therapy one week after transplantation. Some clinical trials have examined the correlation between corticosteroid therapy cessation and the development of chronic graft nephropathy. A prospective randomized study performed by the Canadian Multicentre Study Group which included a large number of patients showed that patients in the withdrawal group were at a higher risk of acute rejection and had a lower graft survival rate than patients maintained on steroids. However, the data collected by Opelz in the Collaborative Transplant Study, with a very large number of patients (minimizing the risk of a positive bias in the selection), showed that patients receiving maintenance immunosuppressive therapy with CsA without steroids have the best long-term patient and graft survival rates. Our own experience is based on a retrospective study of 102 patients who were withdrawn from steroids 58 6 35 months after transplantation (Table 2). They presented a postwithdrawal acute rejection rate of 14.7%, which occurred between 1.8 and 63 months after steroid withdrawal (mean 13 6 13 months). Two patients in the rejection group lost their graft due to rejection. Currently 80 patients (78%) remain steroid free. Finally, the results of a double-blind, multi-center study comparing two corticosteroid regimens plus MMF and CsA for prevention of acute renal allograft rejection are presented. This study was prospectively conducted in 500 renal transplant patients who received CsA and MMF in combination with either standard steroid therapy (control group) or with low doses of steroids and total withdrawal after 3

Pretransplant Frequency of Donor-Specific, IFN-γ-Producing Lymphocytes Is a Manifestation of Immunologic Memory and Correlates with the Risk of Posttransplant Rejection Episodes

Abstract While matching for MHC Ags improves renal allograft survival, closely matched grafts sometimes fail due to rejection, and poorly matched allografts are often well tolerated by the recipient. The severity of the rejection process may partially depend on the presence of environmentally primed T cells in the recipient that cross-react with donor Ags. To test for the presence of primed, donor-specific T cells in humans before transplantation, we used an enzyme-linked immunospot assay for detection of allospecific cytokines produced by individual human PBLs. We demonstrate that this approach detects cytokine production at single cell resolution and detects production of IFN-γ only when there is defined immunologic priming, thus representing a measure of primed donor-specific immunity. Because the environmental Ag exposure of the recipient is not a function of the HLA mismatch between donor and potential recipient, the number of HLA mismatches may not correlate with the frequency of pretransplant, donor-specific IFN-γ-producing PBLs. Studies of donor-specific IFN-γ-producing lymphocytes in a cohort of patients being evaluated for renal transplantation corroborated this hypothesis. Moreover, for recipients of both living and cadaver renal allografts, the pretransplant frequency of donor-specific memory cells correlated with the posttransplant risk of developing acute rejection episodes. This improved ability to define the strength of the allospecific immune response by enzyme-linked immunospot assay may allow improved pairing of recipients with donors and identification of kidney allograft donor-recipient pairs at high risk for acute rejection, thus permitting targeted interventions aimed at prolonging graft survival.

Retrospective study on the impact of hepatitis C virus infection on kidney transplant patients over 20 years.

The majority of chronic hepatitis is ascribable to hepatitis C virus (HCV) infection, whereas the clinical impact has not been understood in kidney transplant recipients. Our current study was carried out to assess the impact of HCV infection on kidney recipients over the long-term, and to investigate the effect and risk of interferon-alpha (IFN-alpha) therapy for chronic active hepatitis C. Hepatitis B surface antigen (HBsAg) and antibody to HCV (HCVAb) were examined prospectively and retrospectively in 280 patients, who underwent kidney transplants in the period from 1973 to 1996. The patient survival rate, the graft survival rate, the incidence of liver dysfunction and the cause of mortality among the HCV infected and noninfected groups were analyzed. IFN-alpha therapy was performed on 10 patients with chronic active hepatitis C. Prevalence of the hepatitis virus was quite high at 34.3% (96/280): the frequency of the HBsAg carrier was 3.2% (9/280), that of the HCVAb carrier was 28.6% (80/280) and that of the both carriers was 2.5% (7/280). The other 184 cases (65.7%) were negative for both HBsAg and HCVAb. Liver dysfunction developed at the significantly higher incidence of 55% in HCVAb carriers compared to the 9.2% of the noninfected group (P<0.01). HCVAb carriers had a poor survival rate in the second decade compared to the noninfected group: 83.7% vs. 88.91% for 10-year survival (P=0.44) and 63.9% vs. 87.9% for 20-year survival (P<0.05). The poor survival rate was a result of the mortality from liver disorder. Five patients died of such disease in the infected groups whereas no noninfected patient died in the same period (p<0.01). As the result of IFN-alpha therapy, biochemical activity normalized or improved in eight cases, whereas the HCV-RNA titer was reduced only in three patients. Only one patient maintained normal biochemical markers and undetectable levels of HCV-RNA for 2 years after treatment. The therapy was discontinued for five patients with the adverse effects of acute rejection, deterioration of diabetes, and depression. HCV infection has a significant impact on kidney transplant recipients over the long term and in particular affects them in the second decade. Our pilot study revealed only partial efficacy of IFN-alpha therapy for HCV-infected recipients, but with the high risk of acute rejection.

Adverse influence of recipient lymphoid resistance to in vitro immunosuppression on the outcome of kidney transplants.

The study investigated whether preoperative in vitro sensitivity of lymphocytes from potential renal transplant recipients could identify patients at increased risk of acute rejection following transplantation and immunosuppression with cyclosporine, azathioprine, and prednisolone. Mixed lymphocyte culture responses were measured preoperatively in the presence of methylprednisolone, CsA, and antithymocyte globulin, and without immunosuppressive agents in 50 transfused recipients of primary cadaver renal transplants. Patients were classified as sensitive if all three immunosuppressive agents produced more than 50% inhibition of their MLC responses, and as resistant if one or more agents failed to produce 50% inhibition. All patients received postoperatively a standardized triple immunosuppressive regimen. Acute rejection was confirmed histologically and treated with Pred with or without ATG or monoclonal antibody OKT3. A total of 29 patients (58%) were sensitive and 21 (42%) were resistant; 4 patients were resistant to 3 agents, 5 were resistant to MP and ATG, 6 were resistant to MP and CsA, and 6 were resistant to MP alone. Sensitive and resistant groups did not differ in age, sex, transfusion history, HLA A, B and DR mismatches or duration of follow-up. The resistant group had a higher rate of graft loss from acute rejection (chi 2 = 6.0, d.f. = 1, P less than 0.02), more episodes of acute rejection (chi 2 = 8.7, d.f. = 3, P less than 0.05), and a higher proportion of patients in whom reflux nephropathy was the cause of renal failure (chi 2 = 18.3, d.f. = 1, P less than 0.001). The resistant group also had a higher proportion of highly sensitized patients and higher serum creatinine concentrations than the sensitive group, although the differences did not reach statistical significance. The study indicates that patients at high risk of acute rejection of renal allografts can be identified by a pretransplant in vitro assay, a finding that could influence recipient selection and immunosuppression.