Immunosuppressive strategies in transplantation

Effective Therapy of a Child Case of Refractory Nephrotic Syndrome with Tacrolimus

We report here the case of a 9-year-old Japanese boy with nephrotic syndrome caused by focal segmental glomerulosclerosis, which was refractory to treatment. Although aggressive immunosuppressive therapy consisting of methylprednisolone pulse therapy combined with cyclosporine A (CsA) and intermittent low density lipoprotein apheresis was effective in overcoming his steroid-resistant state, the child became persistently steroid-dependent, that is, more than 0.75 mg/kg per day of prednisolone combined with CsA was required to maintain a negative test for proteinuria. Since adverse effects of prednisolone, such as short stature, obesity, osteoporosis and cataract, were noted, CsA in his treatment regimen was replaced with tacrolimus at the dose of 0.1 mg/kg per day, with the trough blood level of the drug maintained at around 10 ng/ml. Within 4 months of the inclusion of tacrolimus in the treatment regimen, complete remission was achieved, with no recurrence of the proteinuria, while the prednisolone dose could be tapered to 0.3 mg/kg per day. No adverse effects of tacrolimus were observed. These clinical results suggest that tacrolimus may be the drug of choice in selected patients with refractory nephrotic syndrome, even if pediatric-onset cases, at least those in whom the steroid-sparing effects of CsA is unsatisfactory.

Interleukin 2 receptor antagonists for renal transplant recipients: a meta-analysis of randomized trials1

BACKGROUND

Interleukin 2 receptor antagonists (IL-2Ra) are increasingly used to treat renal transplant recipients. This study aims to systematically identify and summarize the effects of using IL-2Ra as induction immunosuppression, as an addition to standard therapy, or as an alternative to other antibody therapy.

METHODS

Databases, reference lists, and abstracts of conference proceedings were searched extensively to identify relevant randomized controlled trials in all languages. Data were synthesized using the random effects model. Results are expressed as relative risk (RR), with 95% confidence intervals (CI).

RESULTS

A total of 117 reports from 38 trials involving 4,893 participants were included. When IL-2Ra were compared with placebo (17 trials; 2,786 patients), graft loss was not significantly different at 1 year (14 trials: RR 0.84; CI 0.64-1.10) or 3 years (4 trials: RR 1.08; CI 0.71-1.64). Acute rejection was significantly reduced at 6 months (12 trials: RR 0.66; CI 0.59-0.74) and at 1 year (10 trials: RR 0.67; CI 0.60-0.75). At 1 year, cytomegalovirus infection (7 trials: RR 0.82; CI 0.65-1.03) and malignancy (9 trials: RR 0.67; CI 0.33-1.36) were not significantly different. When IL-2Ra were compared with other antibody therapy, no significant differences in treatment effects were demonstrated, but IL-2Ra had significantly fewer side effects.

CONCLUSIONS

Given a 40% risk of rejection, seven patients would need treatment with IL-2Ra in addition to standard therapy, to prevent one patient from undergoing rejection, with no definite improvement in graft or patient survival. There is no apparent difference between basiliximab and daclizumab.

Interleukin 2 receptor antagonists for kidney transplant recipients

BACKGROUND

Interleukin 2 receptor antagonists (IL2Ra) are used as induction therapy for prophylaxis against acute rejection in kidney transplant recipients. Use of IL2Ra has increased steadily, with 38% of new kidney transplant recipients in the United States, and 23% in Australasia receiving IL2Ra in 2002.

OBJECTIVES

This study aims to systematically identify and summarise the effects of using an IL2Ra, as an addition to standard therapy, or as an alternative to other antibody therapy.

SEARCH STRATEGY

The Cochrane Renal Group's specialised register (June 2003), the Cochrane Controlled Trials Register (in The Cochrane Library issue 3, 2002), MEDLINE (1966-November 2002) and EMBASE (1980-November 2002). Reference lists and abstracts of conference proceedings and scientific meetings were hand-searched from 1998-2003. Trial groups, authors of included reports and drug manufacturers were contacted.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in all languages comparing IL2Ra to placebo, no treatment, other IL2Ra or other antibody therapy.

DATA COLLECTION AND ANALYSIS

Data was extracted and quality assessed independently by two reviewers, with differences resolved by discussion. Dichotomous outcomes are reported as relative risk (RR) with 95% confidence intervals (CI).

MAIN RESULTS

One hundred and seventeen reports from 38 trials involving 4893 participants were included. Where IL2Ra were compared with placebo (17 trials; 2786 patients), graft loss was not significantly different at one (RR 0.83, 95% CI 0.66 to 1.04) or three years (RR 0.88, 95% CI 0.64 to 1.22). Acute rejection (AR) was significantly reduced at six months (RR 0.66, 95% CI 0.59 to 0.74) and at one year (RR 0.67, 95% CI 0.60 to 0.75). At one year, cytomegalovirus (CMV) infection (RR 0.82, 95% CI 0.65 to 1.03) and malignancy (RR 0.67, 95% CI 0.33 to 1.36) were not significantly different. Where IL2Ra were compared with other antibody therapy no significant differences in treatment effects were demonstrated, but adverse effects strongly favoured IL2Ra.

REVIEWER'S CONCLUSIONS

Given a 40% risk of rejection, seven patients would need treatment with IL2Ra to prevent one patient having rejection, with no definite improvement in graft or patient survival. There is no apparent difference between basiliximab and daclizumab. IL2Ra are as effective as other antibody therapies and with significantly fewer side effects

Tacrolimus: a further update of its use in the management of organ transplantation

Extensive clinical use has confirmed that tacrolimus (Prograf) is a key option for immunosuppression after transplantation. In large, prospective, randomised, multicentre trials in adults and children receiving solid organ transplants, tacrolimus was at least as effective or provided better efficacy than cyclosporin microemulsion in terms of patient and graft survival, treatment failure rates and the incidence of biopsy-proven acute and corticosteroid-resistant rejection episodes. Notably, the lower incidence of rejection episodes after renal transplantation in tacrolimus recipients was reflected in improved cost effectiveness. In bone marrow transplant (BMT) recipients, the incidence of tacrolimus grade II-IV graft-versus-host disease was significantly lower with tacrolimus than cyclosporin treatment. Efficacy was maintained in renal and liver transplant recipients after total withdrawal of corticosteroid therapy from tacrolimus-based immunosuppression, with the incidence of acute rejection episodes at up to 2 years' follow-up being similar with or without corticosteroids. Tacrolimus provided effective rescue therapy in transplant recipients with persistent acute or chronic allograft rejection or drug-related toxicity associated with cyclosporin treatment. Typically, conversion to tacrolimus reversed rejection episodes and/or improved the tolerability profile, particularly in terms of reduced hyperlipidaemia. In lung transplant recipients with obliterative bronchiolitis, conversion to tacrolimus reduced the decline in and/or improved lung function in terms of forced expiratory volume in 1 second. Tolerability issues may be a factor when choosing a calcineurin inhibitor. Cyclosporin tends to be associated with a higher incidence of significant hypertension, hyperlipidaemia, hirsutism, gingivitis and gum hyperplasia, whereas the incidence of some types of neurotoxicity, disturbances in glucose metabolism, diarrhoea, pruritus and alopecia may be higher with tacrolimus treatment. Renal function, as assessed by serum creatinine levels and glomerular filtration rates, was better in tacrolimus than cyclosporin recipients at up to 5 years' follow-up.

CONCLUSION

Recent well designed trials have consolidated the place of tacrolimus as an important choice for primary immunosuppression in solid organ transplantation and in BMT. Notably, in adults and children receiving transplants, tacrolimus-based primary immunosuppression was at least as effective or provided better efficacy than cyclosporin microemulsion treatment in terms of patient and graft survival, treatment failure and the incidence of acute and corticosteroid-resistant rejection episodes. The reduced incidence of rejection episodes in renal transplant recipients receiving tacrolimus translated into a better cost effectiveness relative to cyclosporin microemulsion treatment. The optimal immunosuppression regimen is ultimately dependent on balancing such factors as the efficacy of the individual drugs, their tolerability, potential for drug interactions and pharmacoeconomic issues.

Expression profiling on chronically rejected transplant kidneys

BACKGROUND

Chronic transplant nephropathy remains a poorly defined inflammatory process that limits the survival rate of most renal transplants. We analyzed the gene profile of chronically rejected kidney transplants to identify candidate genes that characterize chronic transplant nephropathy.

METHODS

To distinguish genes present in normal renal tissue or specific for end-stage renal failure, we compared the gene profiles of 13 chronically rejected kidney transplants with 16 normal kidneys and 12 end-stage polycystic kidneys using a 7K human cDNA microarray. After elimination of genes with signals close to background, 2190 genes were available for statistical analysis.

RESULTS

More than 20% of the examined genes were significantly regulated when compared with the expression level of normal renal tissue (P<0.0003). Hierarchic clustering based on 571 genes differentiated normal and transplant tissue, and transplant and polycystic kidney tissue. Most of these genes encoded proteins involved in cellular metabolism, transport, signaling, transcriptional activation, adhesion, and the immune response. Notably, comprehensive gene profiling of chronically rejected kidneys revealed two distinct subsets of chronically rejected transplants. Neither clinical data nor histology could explain this genetic heterogeneity.

CONCLUSIONS

Microarray analysis of rejected kidneys may help to define different entities of transplant nephropathy, reflecting the multifactorial cause of chronic rejection.

Neither acute rejection nor immunosuppressant drug therapy (cyclosporine or tacrolimus) correlates with expression of either CD40 or CD154 on peripheral blood cells among human cardiac transplant patients

Acute allograft rejection (AAR) is an important cause of graft loss following heart transplantation (HT). Increasing evidence shows that CD40-CD154 interactions play a central role in the immune processes leading to AAR. In this study we investigated the expression of CD40 and CD154 on peripheral blood cells from HT patients so as to determine possible association with AAR. Using two-color flow cytometry, we determined the expression of CD40 and CD154 in 102 samples of peripheral blood taken from 53 adult HT patients and in 17 samples from healthy adult volunteers. Samples from patients were obtained at the same time as endomyocardial biopsy was performed. We analyzed the relationships between the expression of these molecules and the following parameters: immunosuppressive treatment (cyclosporine vs tacrolimus), gender, age, time post-HT, and AAR (indicated by an ISHLT rating > or =3A). The percentages of HT patients' blood samples showing above-normal CD40 or CD154 expression did not differ significantly from those of controls. The percentage of patients' samples showing above-normal CD40 expression decreased with time after HT. Expression of these molecules was not above normal during rejection episodes, and for neither was there any statistically significant correlation between expression level and the immunosuppressor drug.

Mechanisms and management of gingival overgrowth in paediatric transplant recipients: a review

Increasing numbers of children are receiving solid organ transplants namely kidney, liver, heart and lung. Patient survival rates following such transplants are essentially good with much of the success attributable to the development of Cyclosporine A (CyA), an immunosuppressive drug, that minimizes organ rejection. However the gingival overgrowth (GO) associated with the use of CyA is not only disfiguring but in paediatric recipients, may interfere with normal oral development and function.

OBJECTIVE

The aim of this review is to summarize current knowledge concerning the aetiology, pathogenesis and management of gingival overgrowth.

METHODS

Literature pertaining to gingival overgrowth is reviewed with particular reference to the paediatric population. Emphasis is placed on summarizing the evidence pertaining to the effectiveness of intervention.

CONCLUSION

CyA undoubtedly causes gingival overgrowth, the effects and levels of which appears to be more severe in younger patients. There is conflicting evidence as to the effectiveness of oral hygiene regimes, antibiotics and surgery in reducing overgrowth. The introduction of an alternative immunosuppressive agent (Tacrolimus) offers potential as it does not appear to cause overgrowth, although research to date is limited by the small sample size of many of the studies. This is an area in which multicentre studies would be of great value.

Apoptosis and transplantation tolerance

Self-tolerance is maintained by several mechanisms including deletion (via apoptosis) and regulation. Acquired tolerance to allogeneic tissues and organs exploits similar strategies. One key difference between alloantigens and peptide antigens is the enormous number of T cells that are alloreactive. Accumulating evidence suggests that in the face of this large mass of potentially graft-destructive T cells, tolerance requires an initial wave of deletion. This creates a more level playing field in which a smaller number of regulatory T cells can then act to maintain an established tolerant state. Deletion of alloreactive T cells by apoptosis actively promotes immunoregulation as well, by interfering with proinflammatory maturation of antigen presenting cells. This article reviews the immune response to alloantigens, the development and use of both necrotic and apoptotic means of cell death during the evolution of the immune response, and the likely role and mechanisms by which apoptosis promotes, and may even be required for, transplantation tolerance.

Superior T-cell suppression by rapamycin and FK506 over rapamycin and cyclosporine A because of abrogated cytotoxic T-lymphocyte induction, impaired memory responses, and persistent apoptosis

Immunosuppressive therapy is best achieved with a combination of agents targeting multiple activation steps of T cells. In transplantation, cyclosporine A (CsA) or tacrolimus (FK506) are successfully combined with rapamycin (Rap). Rap and CsA were first considered for combination therapy because FK506 and Rap target the same intracellular protein and thus may act in an antagonistic way. However, in clinical studies, FK506+Rap proved to be effective. To date, there is no in vitro data supporting these in vivo findings, and it is unclear whether the observed effects are T-cell mediated. In a human polyclonal allogeneic in vitro model, we found that although combined drug treatment markedly reduced expansion of naive T cells, T-cell activation occurred irrespective of the drug combination used. The induction of cytotoxic effector T cells was reduced by CsA+Rap but completely abolished by FK506+Rap. Importantly, combined immunosuppression allowed generation of memory CD4+ and CD8+ T cells and hence did not result in T-cell anergy. However, FK506+Rap treatment resulted in a reduced number of allospecific memory T cells showing a decreased cell-cycle turnover and cytokine producing capacity. In contrast, CsA+Rap treatment led to increased memory T-cell numbers responding with elevated kinetics. The ability of Rap to promote apoptosis, which contributes to T-cell suppression, remained unaffected upon combination with FK506 or CsA. These data support the combined use of FK506+Rap over CsA+Rap for immunosuppressive therapy.

A prospective, randomized clinical trial of cyclosporine reduction in stable patients greater than 12 months after renal transplantation

BACKGROUND

For stable kidney-transplant recipients receiving triple drug therapy with cyclosporine (CsA), prednisone, and mycophenolate mofetil (MMF), it remains unclear what is the optimal dose of CsA beyond the first 6 to 12 months after transplantation. Complete CsA withdrawal has been associated with a significant incidence of acute rejection and, in some studies, chronic rejection as well.

METHODS

We performed an open, prospectively randomized, controlled clinical trial to determine whether CsA could be safely reduced by 50%. At 1 year or more posttransplant, 64 patients were randomized to either continue their stable-maintenance CsA dose (control group, n=32) or to lower their CsA dose by 50% over a 2 month period (CsA reduction group, n=32). All patients had stable renal-allograft function at the time of enrollment.

RESULTS

Within 6 months of randomization, no episode of acute rejection or graft loss occurred in either group. Patients in the CsA reduction group had a slight but significant increase in their glomerular filtration rate and a trend towards lower serum creatinine. There was also a significant decrease in mean systolic blood pressure, triglycerides, and serum uric acid levels in the CsA reduction group. No significant changes in any of these parameters were observed in the control group.

CONCLUSIONS

This study suggests that a strategy consisting of a 50% CsA reduction is safe and is not associated with the increased risk of acute rejection observed in CsA withdrawal studies. It also has the potential to improve short-term allograft function and appears to reduce cardiovascular risk factors such as hypertension and hyperlipidemia.

Prevention and treatment of severe hemodynamic compromise in pediatric heart transplant patients

Allograft rejection is a leading cause of severe hemodynamic compromise in pediatric heart transplant patients. A triple-drug immunosuppression regimen, which includes a calcineurin inhibitor, antiproliferative agent, and corticosteroid, suppresses the immune system at multiple different levels for optimal graft protection while minimizing the adverse effects of any one particular agent. Some pediatric centers also use induction therapy with anti-T cell antibodies immediately following transplantation as additional rejection prophylaxis. These antibodies augment immunosuppression by either depleting the T cell pool or blocking interleukin-2 receptors on activated T cells. Despite the aggressive preventive measures outlined above, some pediatric heart transplant patients will develop severe hemodynamic compromise, most commonly due to fulminant rejection. Such patients require attention to, and optimization of, the four determinants of cardiac output (heart rate, preload, contractility and afterload) to stabilize the circulation until the rejection can be reversed. Careful administration of volume, diuretics, inotropes, and afterload-reducing agents will meet this goal. Patients with allograft rejection require augmentation of immune suppression to facilitate myocardial recovery. Corticosteroids form the cornerstone of treatment for both cellular and vascular rejection. In patients with refractory cellular rejection, conversion to mycophenolate mofetil or tacrolimus may be appropriate if these agents are not already being used for maintenance immunosuppression. Critically ill patients may additionally benefit from muromonab-CD3 (OKT3) to augment lympholysis. Treatment employed specifically for humoral rejection is prescribed with the intention of suppressing new antibody formation, removing circulating antibody, and improving coronary blood flow. In addition to corticosteroids, cyclophosphamide and antithymocyte globulin or muromonab-CD3, along with plasmapheresis, may improve survival. Systemic heparinization should be considered to minimize coronary thrombosis in patients with humoral rejection. In the future, novel immunosuppressive agents may further assist in the prevention as well as treatment of severe hemodynamic compromise due to rejection in pediatric heart transplant recipients.

The potential of antibody-based immunosuppressive agents for corneal transplantation

Corneal transplantation is a sight-restorative procedure but its success is limited by irreversible graft rejection, which accounts for up to 50 per cent of failures. The normal eye is an immune-privileged site. Multiple mechanisms maintain ocular privilege, including the blood-eye barrier, the lack of blood vessels and lymphatics in the normal cornea, the relative paucity of mature antigen-presenting cells in the central cornea, the presence of immunomodulatory factors in ocular fluids, and the constitutive expressive of CD95L (Fas ligand) within the eye. However, privilege can be eroded by the sequelae of inflammation and neovascularization. Corneal graft rejection in humans is currently suppressed with topical glucocorticosteroids, which are moderately effective. Systemically administered immunosuppressive therapy is of limited efficacy and may be accompanied by unacceptable morbidity. Alternative therapies are needed to improve outcomes. Corneal graft rejection is primarily a cell-mediated response controlled by the CD4+ T cell, and thus CD4 and costimulatory molecule blockade are appealing targets for new therapeutic interventions. A number of monoclonal antibodies have shown promise as immunosuppressants to prolong corneal graft survival in experimental animal models, and may eventually prove to be useful adjuncts to corticosteroids.

A three-arm study comparing immediate tacrolimus therapy with antithymocyte globulin induction therapy followed by tacrolimus or cyclosporine A in adult renal transplant recipients

BACKGROUND

Induction therapy with antithymocyte globulin (ATG) reduces the incidence of acute rejection after transplantation. A study was undertaken to assess the efficacy and safety of ATG induction on tacrolimus-based and cyclosporine A (CsA)-based therapies compared with immediate tacrolimus triple therapy in kidney transplant recipients.

METHODS

In a 6-month, open-label, randomized, prospective study conducted in 30 European centers, 555 renal transplant patients were randomly assigned to tacrolimus triple therapy (Tac triple, n=185), ATG induction with tacrolimus (ATG-Tac, n=186), or ATG induction with CsA microemulsion (ATG-CsA, n=184); all were combined with azathioprine and corticosteroids. The primary endpoint was incidence and time to first acute rejection episode confirmed by biopsy.

RESULTS

Patient demographics and clinical parameters at baseline were similar. Patient and graft survival rates were similar in all groups. The incidence of clinically apparent acute rejection was significantly higher (P=0.003) for Tac triple (33.0%) compared with ATG-Tac (22.6%) and the incidence for ATG-Tac was significantly lower (P=0.004) than for ATG-CsA (37.0%). The incidences of acute rejection confirmed by biopsy (primary endpoint) were 25.4%, 15.1%, and 21.2% for Tac triple, ATG-Tac, and ATG-CsA, respectively (Tac triple vs. ATG-Tac, P=0.004). The incidences of corticosteroid-resistant acute rejection were 7.0% (Tac triple), 4.8% (ATG-Tac), and 10.9% (ATG-CsA) (ATG-Tac vs. ATG-CsA, P=0.038). In the ATG groups, the incidences of leukopenia, thrombocytopenia, serum sickness, fever, and cytomegalovirus infection were significantly higher (P<0.05).

CONCLUSIONS

Acute rejection was significantly lower in the ATG-Tac group compared with the ATG-CsA and Tac triple groups. Significantly more hematologic and infectious adverse events were observed in both ATG induction groups.

Renal transplantation

Renal transplantation offers the best renal replacement therapy for most children with end stage renal disease improving their potential for growth and nutrition, neurodevelopment and quality of life. Advances in organ retrieval and preservation, improved surgical techniques, newer immunosuppressive drugs and prevention and treatment of infections have significantly improved patient and graft survival. The absolute requirements for a transplant are compatible blood group and a negative cytotoxic crossmatch. The immunosuppressive drugs most often used are cyclosporin A (or tacrolimus), azathioprine (or mycophenolate mofetil) and prednisone. Complications following transplantation include episodes of acute rejection, serious bacterial and viral infections, hypertension and recurrence of primary disease in the allograft. Each centre must have standard protocols for pre-transplant evaluation, management of immunosuppression and prevention of infections. Socio-economic factors should be carefully evaluated before offering transplantation to children in developing countries. Preemptive transplantation from a living donor may be a more viable option for these children.

Modulation of the electrophoretic mobility of the linker for activation of T cells (LAT) by the calcineurin inhibitors CsA and FK506: LAT is a potential substrate for PKC and calcineurin signaling pathways

The linker for activation of T cells (LAT) is essential for T cell activation. Cyclosporin A (CsA) and FK506, inhibitors of T cell proliferation, have been very useful for preventing autoimmune and inflammatory disease and graft rejection. However, both compounds are associated with side effects. We show that TCR ligation in the presence of FK506 or CsA induced rapid modifications in LAT that modulate the electrophoretic mobility of the molecule in SDS-PAGE. Calcineurin, a target for CsA and FK506, dephosphorylated LAT in vitro and restored its electrophoretic mobility. Stimulating T cells with the protein kinase C (PKC) activator PMA induced a shift in the mobility of LAT, whereas inhibitors of PKC blocked the effect of PMA. Thus, manipulating calcineurin or PKC activation alters the electrophoretic mobility of LAT. These results shed light on the molecular actions of CsA and FK506 in T cells and implicate LAT in mediating the drugs' actions.

Piceatannol in combination with low doses of cyclosporine A prolongs kidney allograft survival in a stringent rat transplantation model

BACKGROUND

The discovery of new immunosuppressive agents has enhanced short-term graft survival. However, current immunosuppressants often induce toxicities that limit their clinical use. Thus, there is a need for new immunosuppressants for use in clinical transplantation. Piceatannol blocks Syk and ZAP-70, tyrosine kinases involved in immune cell activation. We examined whether piceatannol prolongs kidney allograft survival in the stringent ACI-to-Lewis rat model.

METHODS

Kidney recipients were divided into four groups. Group 1 (n=8) received piceatannol 30 mg/kg per day intravenously and cyclosporine A (CsA) 2 mg/kg per day intramuscularly from day -3 to day 7 after transplantation. At day 8, piceatannol was reduced to 10 mg/kg per day and the combined treatment continued until day 60. Group 2 (n=9) received 2 mg/kg per day CsA alone from day -3 to day 60. Group 3 (n=4) received piceatannol alone as in group 1. Group 4 (n=2) received only the vehicle dimethyl sulfoxide from day -3 to day 60. Graft rejection was defined as either a serum creatinine level more than 2 mg/dL or animal death.

RESULTS

Group 1 animals survived for at least 115 days (n=8, P<0.05), with several animals maintaining their grafts for more than 200 days. In contrast, 8 of 9 animals in group 2 rejected their grafts within 10 days of transplantation; one animal survived for 71 days. Excellent graft function was maintained in group 1 animals despite withdrawal of immunosuppression.

CONCLUSIONS

These results are the first to show that piceatannol, when combined with subtherapeutic dosages of CsA, prevents graft rejection, suggesting that targeting Syk and Zap could be useful for preventing graft rejection.

Induction of tolerance in composite-tissue allografts

BACKGROUND

Transplantation of composite-tissue allograft (CTA) such as the human hand recently became a clinical reality. The high risks associated with the use of lifelong immunosuppression have been the prohibiting factor in the routine use of the CTA transplants. In this article, we present a new approach of inducing long-term, donor-specific tolerance to CTAs without recipient preconditioning and need for chronic immunosuppression.

METHODS

We have developed a clinically applicable 35-day protocol that induces donor-specific tolerance in a rat hindlimb-transplantation model across major histocompatibility complex (MHC) barrier [Lewis-Brown-Norway (LBN, RT1 -->F1) to Lewis (LEW, RT1 ) by using cyclosporine A (CsA) and a mouse monoclonal antibody against rat alphabeta-T-cell receptor (TCR) to systemically eliminate alloresponsive cells. Standard skin grafting, flow cytometry (FC), and mixed lymphocyte reaction (MLR) were used to assess efficacy of immunodepletion and confirm donor-specific tolerance and chimerism.

RESULTS

Under this protocol long-term tolerance (>720 days) was induced in all (n=5) CTA recipients across the MHC barrier without further need for immunosuppression. Tolerance was confirmed in all limb-allograft recipients by skin grafting in vivo and by MLR in vitro. The animals rejected third-party grafts, indicating immunocompetence.

CONCLUSIONS

In this CTA model, combined protocol of alphabeta-TCR monoclonal antibody and CsA resulted in induction of donor-specific tolerance across the MHC barrier without recipient conditioning. We believe that our findings will foster development of new therapeutic strategies and expand clinical applications for composite-tissue transplantation.

New insights into the interactions between T-cell costimulatory blockade and conventional immunosuppressive drugs

OBJECTIVE

To determine the precise in vivo interaction between T-cell costimulatory blockade and conventional immunosuppression in transplantation.

SUMMARY BACKGROUND DATA

Blocking B7 or CD154 T-cell costimulatory activation pathways prevents allograft rejection in small and large animal transplant models and is considered a promising strategy for clinical organ transplantation.

METHODS

A fully MHC-mismatched vascularized mouse cardiac allograft model was used to test the interactions between anti-CD154 or CTLA4Ig monotherapy and conventional immunosuppressive drugs in promoting long-term graft acceptance. The frequency of alloreactive T cell was measured by ELISPOT. Chronic rejection was examined by histology.

RESULTS

Cyclosporine, tacrolimus, and anti-IL-2R monoclonal antibody therapy abrogated the effect of a single-dose protocol of anti-CD154 therapy. In contrast, rapamycin acted synergistically with anti-CD154 therapy in promoting long-term allograft survival. The addition of calcineurin inhibitors did not abolish this synergistic effect. Intense CD154-CD40 blockade by a multiple-dose schedule of anti-CD154 resulted in long-term graft survival and profound alloreactive T-cell unresponsiveness and overcame the opposite effects of calcineurin inhibitors. CTLA4Ig induced long-term graft survival, and the effect was not affected by the concomitant use of any immunosuppressive drugs.

CONCLUSIONS

The widespread view that calcineurin inhibitors abrogate the effects of T-cell costimulatory blockade should be revisited. Sufficient costimulatory blockade and synergy induced by CD154 blockade and rapamycin promote allograft tolerance and prevent chronic rejection.

Single-agent immunosuppression after liver transplantation: what is possible?

Orthotopic liver transplantation is a life saving and life enhancing procedure. The development of immunosuppressive drugs has contributed to the high rate of success in terms of both patient and graft survival. However, the considerable adverse effects of these therapies are affecting long-term outcomes of transplant recipients. Complications related to immunosuppression are responsible for the majority of deaths in patients surviving more than 1 year. Therefore, the search for an optimal immunosuppressive regimen has become of paramount importance. The liver has proved to be an 'immunologically privileged' organ, capable in several animal models to be accepted as an allograft without any intervention on the immune system of the recipient. In some human liver allografts acceptance of the new organ is recognised after withdrawal of immunosuppressants, but prior identification of such individuals is not yet possible, thus negating this management option. Graft-recipient interaction is peculiar in liver transplantation: acute cellular rejection does not always need to be treated, and if it is not severe, appears to be associated with a better survival of both patient and graft. In the last decade there has been an evolution of immunosuppressive protocols, driven by empirical observation and a deeper understanding of immunological events after transplant. However, most modifications have been made because of the necessity to reduce long-term drug related morbidity and mortality. Withdrawal of corticosteroids has proven to be safely achievable in most patients, with no deleterious effects on patient or graft survival but with a great benefit in terms of reduction of incidence of metabolic and cardiovascular complications. Long-term 'steroid-free' regimens are therefore now widely used. Patients with stable graft function can be easily maintained using a single drug usually after 6 or 12 months and usually with a calcineurin inhibitor. The more evolved step of using monotherapy ab initio has also proven to be effective in a few studies and needs to be explored further. In the future new strategies will be designed to help the development of tolerance of the allograft, selectively stimulating instead of suppressing the immune reaction of the recipient.

Prevention of chronic rejection in murine cardiac allografts: a comparison of chimerism- and nonchimerism-inducing costimulation blockade-based tolerance induction regimens

We have previously described a nonirradiation-based regimen combining costimulation blockade, busulfan, and donor bone marrow cells that promotes stable, high level chimerism, deletion of donor-reactive T cells, and indefinite survival of skin allografts in mice. The purpose of the current study is to determine the efficacy of this tolerance regimen in preventing acute and chronic rejection in a vascularized heart graft model and to compare this regimen with other putative tolerance protocols. Mice receiving costimulation blockade (CTLA4-Ig and anti-CD40 ligand) alone or in combination with donor cells enjoyed markedly prolonged heart graft survival and initially preserved histological structure. However, tolerance was not achieved, as evidenced by the eventual onset of chronic rejection characterized by obliterative vasculopathy and the rejection of secondary skin grafts. In contrast, following treatment with costimulation blockade, busulfan, and bone marrow, heart grafts survived indefinitely without detectable signs of chronic rejection or structural damage, even 100 days after placement of a secondary donor skin graft. We detected multilineage chimerism in peripheral blood, spleen, lymph nodes, and thymus, and peripheral deletion of donor-reactive cells was complete by day 90. These findings indicate that only the CD40/CD28 blockade chimerism induction regimen prevents both acute and chronic rejection of vascularized organ transplants. Further testing of these strategies in a preclinical large animal model is warranted.

Renal Transplantation - Calcutta Experience

31 renal transplant procedures have been performed at this centre. Renal donors were father in 4, mother in 4, brother in 12, sister in 4, brother-in-law in 1 and wives in 6 cases. Median age of recipients and donors was 35.2 years (20-55) and 38.3 years (24-60) respectively. After a mean follow up of 15.7 months (2-40), graft survival was 96.7% and patient survival 90-3%. Three patients (9.6%) required surgical re-exploration, one each for, peri-graft haematoma, arterial kink and graft artery thrombosis. 6 patients (19.3%) required anti rejection therapy with resultant complete normalisation of graft functions. Medical complications noted were post transplant diabetes mellitus in 6 (19.3%), azathihoprine induced bone marrow suppression in 1(3.2%), tuberculosis in 2 (6.4%), post transplant erythrocytosis in 2 (6.4%) and recurrent urinary tract infection (UTI) in one (3.2%) patients. 3 patients (9.6%) died with functioning graft, one due to lung infection and the other due to haemorrahagic pancreatitis and third due to infective endocarditis.

The effects of rapamycin in murine peripheral nerve isografts and allografts

The FKBP-12-binding ligand FK506 has been successfully used to stimulate nerve regeneration and prevent the rejection of peripheral nerve allografts. The immunosuppressant rapamycin, another FKBP-12-binding ligand, stimulates axonal regeneration in vitro, but its influence on nerve regeneration in peripheral nerve isografts or allografts has not been studied. Sixty female inbred BALB/cJ mice were randomized into six tibial nerve transplant groups, including three isograft and three allograft (C57BL/6J) groups. Grafts were left untreated (groups I and II), treated with FK506 (groups III and IV), or treated with rapamycin (groups V and VI). Nerve regeneration was quantified in terms of histomorphometry and functional recovery, and immunosuppression was confirmed with mixed lymphocyte reactivity assays. Animals treated with FK506 and rapamycin were immunosuppressed and demonstrated significantly less immune cell proliferation relative to untreated recipient animals. Although every animal demonstrated some functional recovery during the study, animals receiving an untreated peripheral nerve allograft were slowest to recover. Isografts treated with FK506 but not rapamycin demonstrated significantly increased nerve regeneration. Nerve allografts in animals treated with FK506, and to a lesser extent rapamycin, however, both demonstrated significantly more nerve regeneration and increased nerve fiber widths relative to untreated controls. The authors suggest that rapamycin can facilitate regeneration through peripheral nerve allografts, but it is not a neuroregenerative agent in this in vivo model. Nerve regeneration in FK506-treated peripheral nerve isografts and allografts was superior to that found in rapamycin-treated animals. Rapamycin may have a role in the treatment of peripheral nerve allografts when used in combination with other medications, or in the setting of renal failure that often precludes the use of calcineurin inhibitors such as FK506.

Positive effect on T-cell regulatory apoptosis by mycophenolate mofetil

The regulatory benefit of apoptosis (activation-induced cell death, AICD) in T cells may be impacted by immunosuppressive agents. We examined this for mycophenolate mofetil (MMF) compared with cyclosporine (CYA). Peripheral blood leukocytes (PBL) were stimulated by either Staph enterotoxin B (SEB) or by anti-CD3 plus anti-CD28. Cell division analysis (sequential reduction in carboxyflourescein diacetate succinimidyl ester, CFSE) was used to measure proliferation and determine status of different cell generations. Apoptosis was measured by annexin V staining, and FasL expression by anti-FasL antibody staining, of activated cells using flow cytometry. CSA and mycophenolic acid (MPA, the active agent of MMF) were added in titration in 3-day cultures. We found that CSA caused diminution in apoptosis but MPA increased it with SEB stimulation. The CSA effect on apoptosis was present when a more calcineurin-dependent stimulus. anti-CD3+ anti-CD28, was used but the MPA effect was less, producing a decrease only in the undivided cells. To look more directly at the differential effect on calcineurin-dependent AICD gene induction of the two agents, we measured Fas-L expression with anti-CD-3 + CD28 stimulation, and confirmed that CYA caused a major decrement in appearance of Fas-L, whereas MPA caused a converse accumulation of it. This seems to be explained by the block more distal in cell activation, resulting in a build-up of a precursor in the activation pathways. We conclude that MMF treatment may be rationale as an adjunct to calcineurin inhibitor treatment because of its converse effect on T cell regulatory apoptosis.

Detection of an up-regulation of a group of chemokine genes in murine cardiac allograft in the absence of interferon-gamma by means of DNA microarray

BACKGROUND

[corrected] Interferon (IFN)-gamma and the IFN-gamma-dependent pathway are prominent in vascularized allograft during acute rejection. However, IFN-gamma deficient (IFN-gamma-/-) mice can rapidly reject cardiac allografts. To bring the alternative pathway during allograft rejection into more precise focus, we investigated the gene expression profile in murine cardiac allografts in IFN-gamma-/- mice by means of DNA microarray.

MATERIAL AND METHOD

We screened for gene expression changes in murine cardiac allografts of BALB/c H-2d into both wild-type C57BL/6 H-2b (n=3) and IFN-gamma-/- C57BL/6 H-2b(IFN-gamma-/-, n=4) using Affymetrix oligonucleotide arrays to monitor more than 11,000 genes and expressed sequence tag (ESTs). The heart was heterotopically transplanted. Transplanted hearts were harvested on day 5. As a control, isografts (C57BL/6 to C57BL/6) were also harvested on day 5.

RESULTS

On day 5, 64 of the 84 genes induced in the allografts in wild-type mice were not up-regulated in IFN-gamma-/- mice. We identified a group of 54 genes that were up-regulated in allografts in IFN-gamma-/- mice. Several chemokine genes, including monocyte chemoattractant protein=1 and macrophage inflammatory protein, were induced in the allografts in both wild-type and IFN-gamma-/- mice. Interestingly, a group of genes, including C10-like chemokine and platelet factor 4, were specifically induced in the IFN-gamma-/- mice.

CONCLUSION

DNA microarray analysis reveals a unique pattern of mRNA expression in allografts in IFN-gamma-/- mice as well as a group of genes induced in cardiac allografts in both wild-type and IFN-gamma-/- mice, including monocyte chemoattractant protein-1 and monocyte chemoattractant protein-1.

Perioperative care of the lung transplant patient

Improvements in the perioperative management of lung transplant recipients have produced a 90% survival in the first 30 days following surgery. Detailed attention to donor organ procurement and preservation of the allograft are important in ensuring an early successful outcome. Early antibacterial administration based on donor or pretransplant cultures and antiviral therapy in CMV-negative recipients assist in avoiding early infectious complications. Development of hypoxemia or hemodynamic instability in the perioperative period requires a rapid, systematic evaluation with attention to mechanical, immunologic, or infectious causes. Nonpulmonary complications are not infrequent in lung transplant recipients.

Long-term care of pediatric renal transplant patients: from bench to bedside

In this review, we discuss current and future issues in the management of pediatric renal transplant recipients, including the optimization of long-term graft function and the minimization of complications caused by immunosuppression. Long-term management involves not only the monitoring of graft function but also the identification of patients at risk for the development of complications. The identification of patients with immunoreactive or immunoregulatory responses can be performed molecular monitoring of the immune response. Also, the use of frequent surveillance kidney biopsies, surrogate markers of chronic rejection, and glomerular filtration rate will be a part of future management. Identifying high-risk patients enables the physician to optimize immunosuppression to limit acute rejection. Short-and long-term management of pediatric transplant patients also includes adequate monitoring of growth and the monitoring for post-transplant lymphoproliferative disease. Ongoing clinical trials are underway that focus on these novel approaches in caring for pediatric transplant recipients.

Combined therapy of tacrolimus and corticosteroids in cyclosporin-resistant or -dependent idiopathic focal glomerulosclerosis: a preliminary uncontrolled study with prospective follow-up

BACKGROUND

Cyclosporin has improved the outcome for steroid-resistant patients with focal glomerulosclerosis, but there is a proportion of patients that are either cyclosporin-resistant or suffer relapses, needing long-term therapy to sustain the remission. In these cases, preliminary reports suggest that tacrolimus could be an alternative therapy, but to date the evidence is limited to small series of patients with no long-term follow-up.

METHODS

In this study we analysed the efficacy and safety of a combined therapy of tacrolimus and steroids in 25 patients (mean serum creatinine= 1.24+/-0.49 mg/dl; mean proteinuria=10.2+/-9.5 g/day; mean serum albumin=2.4+/-0.58 g/dl) with idiopathic primary focal glomerulosclerosis and proven resistance to or dependence on cyclosporin A.

RESULTS

After a 6 months trial of tacrolimus and steroids, proteinuria decreased in 17 patients (68%) (complete remission in 10 patients (40%), partial remission in two patients (8%) and a moderate reduction in proteinuria to levels <3 g/day was seen in five additional patients (20%)). The only predictor of response to tacrolimus was a previous response to cyclosporin and prednisone, either as a complete or partial remission (remission rate 75% vs 15.3; P=0.036). Mean time to remission was 112+/-24 days. After tacrolimus discontinuation, 13/17 patients (76%) relapsed and were treated with a second trial of tacrolimus for 1 year, achieving complete remission in five patients (38.4%), partial remission in four patients (30.7%) and reduction of proteinuria <3 g/day in four patients (30.7%). After 2 years of follow-up, 12 patients (48%) were on sustained remission. The main side effect was acute reversible nephrotoxicity (40%). Predictors of renal toxicity were age (P=0.037), baseline creatinine (P=0.046) and tacrolimus trough level (P=0.001).

CONCLUSIONS

We conclude that combined therapy of tacrolimus and steroids induce sustained remission of proteinuria in a significant number of patients with idiopathic focal glomerulosclerosis whose disease was not controlled by the standard therapy of steroids and cyclosporin A.

Pharmacokinetic considerations in the treatment of inflammatory bowel disease

This review describes the pharmacokinetics of the major drugs used for the treatment of inflammatory bowel disease. This information can be helpful for the selection of a particular agent and offers guidance for effective and well tolerated regimens. The corticosteroids have a short elimination half-life (t1/2beta) of 1.5 to 4 hours, but their biological half-lives are much longer (12 to 36 hours). Most are moderate or high clearance drugs that are hepatically eliminated, primarily by cytochrome P450 (CYP) 3A4-mediated metabolism. Prednisone and budesonide undergo presystemic elimination. Any disease state or comedication affecting CYP3A4 activity should be taken into account when prescribing corticosteroids. Depending on the preparation used, 10 to 50% of an oral or rectal dose of mesalazine is absorbed. Rapid acetylation in the intestinal wall and liver (t1/2beta 0.5 to 2 hours) and transport probably by P-glycoprotein affect mucosal concentrations of mesalazine, which apparently determine clinical response. Any clinical condition influencing the release and topical availability of mesalazine might modify its therapeutic potential. Metronidazole has high (approximately 90%) oral bioavailability, with hepatic elimination characterised by a t1/2beta of 6 to 10 hours and a total clearance of about 4 L/h/kg. Ciprofloxacin is largely excreted unchanged both renally (about 45% of dose) and extrarenally (25%), with a relatively short t1/2beta (3.5 to 7 hours). Thus, renal function affects the systemic availability of ciprofloxacin. Both mercaptopurine and its prodrug azathioprine are metabolised to active compounds (6-thioguanine nucleotides; 6-TGN) by hypoxanthine-guanine phosphoribosyltransferase and to inactive metabolites by the polymorphically expressed thiopurine S-methyltransferase (TPMT) and xanthine oxidase. Patients with low TPMT activity have a higher risk of developing haemopoietic toxicity. Both mercaptopurine and azathioprine have a short t1/2beta (1 to 2 hours), but the t1/2beta of 6-TGN ranges from 3 to 13 days. Therapeutic response seems to be related to 6-TGN concentration. Almost complete bioavailability has been observed after intramuscular and subcutaneous administration of methotrexate, which is predominantly (85%) excreted as unchanged drug with a t1/2beta of up to 50 hours. Thus, renal function is the major determinant for disposition of methotrexate. Cyclosporin is slowly and incompletely absorbed. It is extensively metabolised by CYP3A4/5 in the liver and intestine (median t1/2beta and clearance 7.9 hours and 0.46 L/h/kg, respectively), and inhibitors and inducers of CYP3A4 can modify response and toxicity. Infliximab is predominantly distributed to the vascular compartment and eliminated with a t1/2beta between 10 and 14 days. No accumulation was observed when it was administered at intervals of 4 or 8 weeks. Methotrexate may reduce the clearance of infliximab from serum.

Cyclosporin: an updated review of the pharmacokinetic properties, clinical efficacy and tolerability of a microemulsion-based formulation (neoral)1 in organ transplantation

Cyclosporin is a lipophilic cyclic polypeptide immunosuppressant that interferes with the activity of T cells chiefly via calcineurin inhibition. The original oil-based oral formulation of this drug (Sandimmun)l was characterised by high intra- and interpatient pharmacokinetic variability, with poor bioavailability in many patients; a novel microemulsion formulation (Neoral)1 was therefore developed to circumvent these problems. Studies show increases, attributable chiefly to improved absorption in patients who absorb the drug only poorly from the original formulation, in mean systemic exposure to cyclosporin with the microemulsion, with no clinically significant differences in tolerability or drug interaction profiles. Cyclosporin microemulsion is at least as effective as the oil-based formulation in renal, liver and heart transplant recipients, with trends towards decreased incidence of acute rejection with the microemulsion formulation in some (statistically significant in a few) trials. Cyclosporin microemulsion and tacrolimus appear to have similar efficacy in preventing acute rejection episodes in most renal, pancreas-kidney, liver and heart transplant recipients. However, there are indications of superior efficacy for tacrolimus in some trials, particularly in the prevention of severe acute rejection and in Black transplant recipients. Current 12-month data also indicate equivalent efficacy of sirolimus in renal transplantation. Conversion from the oil-based to microemulsion formulation in stable renal, liver and heart transplant recipients is achievable with no change in acute rejection rates. The addition of an anti-interleukin-2 receptor monoclonal antibody and/or mycophenolate mofetil to cyclosporin microemulsion plus corticosteroids decreases rates of acute rejection; corticosteroid withdrawal without increased acute rejection rates was also achieved on the addition of these agents in some trials. Pharmacoeconomic analyses have shown savings in direct healthcare costs in kidney or liver transplantation when cyclosporin microemulsion is used in preference to the oil-based formulation, although studies incorporating indirect costs or expressing costs in terms of therapeutic outcomes are currently unavailable.

CONCLUSIONS

The introduction of cyclosporin microemulsion has consolidated the place of the drug as a mainstay of therapy in all types of solid organ transplantation; research into optimisation of outcomes through more effective therapeutic monitoring in patients receiving this formulation is ongoing. Several novel immunosuppressants have been introduced in recent years: further clinical and pharmacoeconomic research will be needed to clarify the relative positioning of these agents, particularly with respect to specific patient groups. Other new drugs (basiliximab/daclizumab and mycophenolate mofetil) offer particular advantages when used in combination with cyclosporin.

Tuberculin-induced lymphocyte proliferation in whole blood: an antigen specific method for assessing immunosuppressive agents

Antigen-stimulated whole blood cultures have not been used to study the effects of immunosuppressive drugs. The aim of this study was to assess the potential usefulness of tuberculin purified protein derivative (PPD)-stimulated lymphocyte proliferation in whole blood for studying the effects of T cell inhibitory agents. We have investigated whether PPD causes antigen specific T cell proliferation, and the role of the major histocompatibility complex class II (MHC class II), co-stimulation and IL-2 in the development of this response. We have also studied the effects of prednisolone and cyclosporin on lymphocyte proliferation. Heparinised blood from healthy volunteers was diluted in culture medium and incubated with PPD. Cell proliferation, measured by liquid scintillation counting, was maximal using 1000 units/ml PPD incubated in 10% whole blood for 6-7 days. A population of large CD4+ lymphocytes appeared in cultures incubated with PPD, suggesting that the major responding population was composed of T lymphocytes. There was no significant response to the negative control antigen KLH, indicating that proliferation was antigen specific. Monoclonal antibodies (mAbs) against MHC, CD2, CD26, CD28 and IL-2 inhibited proliferation. Prednisolone was more potent than cyclosporin in this assay (IC50 values; prednisolone 20 nmol, cyclosporin 278 nmol). For the first time, this report shows that the PPD causes antigen specific lymphocyte proliferation in whole blood, which is dependent on antigen presentation via MHC class II, co-stimulation and IL-2 production. Because the proliferative response is dependent on the major interactions that lead to T cell activation, this simple assay can be used to assess the effects of novel immunomodulators.

Daclizumab: a review of its use in the management of organ transplantation

The humanised monoclonal antibody daclizumab is an immunosuppressive agent that reduces acute rejection in solid organ transplantation. It is specific for the alpha subunit (Tac/CD25) of the interleukin (IL)-2 receptor on activated T cells and achieves immunosuppression by competitive antagonism of IL-2-induced T cell proliferation. When added to standard triple immunosuppression regimens, daclizumab significantly reduces the rate of acute rejection at 1 year in renal transplantation by 36% and there are indications that it may be effective in other solid organ transplantations. Three-year outcomes of two phase III clinical trials in renal transplantation indicate similar values for graft and patient survival between daclizumab and placebo when given in addition to triple immunosuppression; however, these pivotal trials were not designed with sufficient power to demonstrate any statistical significance. The addition of daclizumab induction shows potential in allowing calcineurin inhibitor- and corticosteroid-sparing regimens without increasing the rate of acute graft rejection or adverse effects in renal and liver transplantation. Preliminary reports indicate that daclizumab may also be a useful agent in delayed graft function and graft versus host disease (GVHD). Further investigation of its efficacy in these groups and in children is needed. Data from clinical trials show daclizumab to be well tolerated in solid organ transplantation. It does not increase the incidence of infection, including cytomegalovirus infection, when compared with placebo or no induction groups. Preliminary comparative data with muromonab CD3 indicate that daclizumab may be associated with a lower rate of infectious complications and similar or better efficacy.

CONCLUSIONS

In conclusion, daclizumab has been proven to reduce acute rejection in renal transplant recipients when given in addition to traditional baseline immunosuppression. It has shown potential to reduce acute rejection in other solid organ transplants; however, well designed, randomised studies are required to confirm this. Clinical experience from trials to date indicate that daclizumab has a tolerability profile similar to placebo with no significant effect on the incidence of infection. The relative efficacy and tolerability of daclizumab compared with other induction agents has yet to be defined. Available data suggest that daclizumab may allow the use of calcineurin inhibitor-sparing and corticosteroid-sparing regimens and may have potential in the treatment of GVHD.

Selective inhibitor of Janus tyrosine kinase 3, PNU156804, prolongs allograft survival and acts synergistically with cyclosporine but additively with rapamycin

Janus kinase 3 (Jak3) is a cytoplasmic tyrosine (Tyr) kinase associated with the interleukin-2 (IL-2) receptor common gamma chain (gamma(c)) that is activated by multiple T-cell growth factors (TCGFs) such as IL-2, -4, and -7. Using human T cells, it was found that a recently discovered variant of the undecylprodigiosin family of antibiotics, PNU156804, previously shown to inhibit IL-2-induced cell proliferation, also blocks IL-2-mediated Jak3 auto-tyrosine phosphorylation, activation of Jak3 substrates signal transducers and activators of transcription (Stat) 5a and Stat5b, and extracellular regulated kinase 1 (Erk1) and Erk2 (p44/p42). Although PNU156804 displayed similar efficacy in blocking Jak3-dependent T-cell proliferation by IL-2, -4, -7, or -15, it was more than 2-fold less effective in blocking Jak2-mediated cell growth, its most homologous Jak family member. A 14-day alternate-day oral gavage with 40 to 120 mg/kg PNU156804 extended the survival of heart allografts in a dose-dependent fashion. In vivo, PNU156804 acted synergistically with the signal 1 inhibitor cyclosporine A (CsA) and additively with the signal 3 inhibitor rapamycin to block allograft rejection. It is concluded that inhibition of signal 3 alone by targeting Jak3 in combination with a signal 1 inhibitor provides a unique strategy to achieve potent immunosuppression.

Donor platelet and leukocyte load identify renal allografts at an increased risk of acute rejection

BACKGROUND

A reduction in acute rejection may reduce graft losses from chronic rejection, benefiting the recipient and helping ease the huge donor organ shortfall in the UK. The prediction of recipients at greater risk of acute rejection might justify the administration to them of more potent immunosuppression, but defining this group on clinical parameters has been largely unsuccessful. Events impacting on the kidney by the time of donation may, if detectable histologically, predict those kidneys more likely to undergo rejection.

METHODS

A prospective immunohistochemical analysis was undertaken to detect P-Selectin (PS), E-Selectin (ES), platelets, leukocyte common antigen, macrophages, T cells, and neutrophils in the pretransplant biopsies of 77 adult renal transplant recipients. Twenty-nine (38%) of this group rejected.

RESULTS

A significantly increased number of recipients rejected if the donor biopsy was PS positive (63 vs. 24%, P=0.0007), contained five or more leukocytes/glomerulus (48 vs. 21%, P=0.03), contained >9.3 leukocytes/high power field (46.5 vs. 10.5%, P=0.006) or was both PS positive and contained >9.3 leukocytes/high power field (61.9 vs. 0.0%, P=0.0001). The PS was mostly of platelet origin and the majority of leukocytes were macrophages. Only previous CMV or any current infection in the donor correlated with the immunohistochemical changes.

CONCLUSIONS

These immuno-histochemical changes are present before transplantation, which allows the prediction of recipients at both a higher and a lower risk of acute rejection, enabling the administration of recipient tailored immunosuppression, and supports the use of additional therapeutic intervention to reduce the injury response both within the recipient and the donor.

Ação do soro de cabra anti-soro de coelho imunizado ou não com células linfóides do doador sobre o alotransplante cardíaco em ratos: immunosupression of goat antiserum against rabbit serum immunized or not with donor lymphoid cells

INTRODUÇÃO: A rejeição imunológica é uma das principais causas da perda de órgãos transplantados. A tentativa do controle da reação imunológica é clinicamente feita através da imunossupressão inespecífica e experimentalmente também por bloqueio específico. O alotransplante cardíaco em ratos pela técnica de ONO,K é um bom método para avaliação clínica da rejeição e de estudos voltados para o controle da rejeição. Objetivo : estudar o efeito de um anti-antisoro linfocitário, anti-linfócitos do doador sobre a rejeição do alotransplante cardíaco de ratos Wistar para ratos Holtzman. MÉTODOS: o soro anti-linfocitário (SAL) foi obtido através da imunização de coelhos com linfócitos obtidos de gânglios linfáticos da cadeia mesentérica de ratos Wistar, em solução de Tyrode, contendo 3x10(9) células/ ml. A inoculação de 3 coelhos foi feita com 1 ml da suspensão celular e 1 ml de adjuvante completo de Freund. Duas semanas após a primeira inoculação fez-se 4 doses semanais de reforço. Os coelhos foram sangrados na 5ª semana, quando então foram separados os soros. A titulação dos soros foi realizada pelo teste de citotoxicidade, sendo verificado que ambos apresentaram título de 1:1024. A dosagem de proteínas mostrou albumina com 3,1 e 2,7 g% e globulinas com 3,5 e 2,9 g%, sendo o normal 3,7 e 2,2 g% respectivamente. Os dois SAL foram misturados. Duas cabras foram inoculados, com 3 ml da mistura desses SAL, associados a 2 ml de adjuvante de Freund. As doses de reforço com 5 ml do SAL foram iniciadas 2 semanas após. A cabra A recebeu 8 doses (1,4 g de globulinas). A cabra B recebeu 4 doses de reforço (0,7 g de globulinas). Uma semana após a última inoculação retirou-se 125 ml de sangue de cada cabra, fazendo a separação dos anti-soro anti-SAL (ASAL). Uma terceira cabra C foi imunizada com soro normal de coelho. A determinação de precipitinas foi feita pelo método de OUCHTERLONY. O ASAL A teve título de 1:64 e B e C título de 1:128. Os ASAL A e B foram capazes de bloquear "in vitro" a atividade citotóxica do SAL até a diluição de 1:2 do SAL. O soro de cabra anti-soro normal de coelho (SCANC) não foi capaz de bloquear a citotoxicidade do SAL. Os animais submetidos a transplante cardíaco foram divididos em 2 grupos controles um normal com 10 ratos (C1) e outro (C2) com 5 ratos que recebeu 1,0 ml endovenoso de SCANC. O grupo de ratos testes A foi composto por 19 ratos distribuídos em 3 subgrupos. Subgrupo A1 com 5 ratos recebeu 0,5 ml do ASAL A, via endovenosa, logo após a cirurgia,o subgrupo A2 com 7 ratos recebeu 1.0 ml do ASAL A nas mesmas condições e o subgrupo A3 também com 7 ratos recebeu 1,0 ml no dia da cirurgia e 1,0 ml nos outros 2 dias consecutivos. O grupo de ratos testes B que recebeu o ASAL B foi igual ao grupo A. A avaliação dos corações transplantados foi diária através da palpação abdominal. O tempo máximo de seguimento foi de 243 dias. Os corações considerados rejeitados foram retirados e feito estudos histológicos. RESULTADOS: o período de rejeição dos grupos foi : controles C1 e C2 foram 11,9 e 14,6 dias, respectivamente; no subgrupo A1 apenas um rato teve sobrevida cardíaca significante (153 dias), nos demais ela variou de 9 a 15 dias; no subgrupo A2 a sobrevida do coração foi significante e variou de 23 a 230 dias; no subgrupo A3 apenas 5 corações tiveram sobrevida significante que variou de 29 a 190 dias. A sobrevida dos corações transplantados do grupo B foi significante para um animal de cada subgrupo (120,132 e 129 dias). Os corações com sobrevida longa foram retirados batendo. Os demais corações foram rejeitados dentro do período de variação dos grupos controles. CONCLUSÕES: O soro de cabra anti-soro anti-linfócitos do doador, com maior período de imunização, foi capaz de bloquear a resposta imune de rejeição dos corações transplantados nas doses de 1,0 e 3,0 ml. Os ratos que não promoveram a rejeição aguda dos corações transplantados não apresentaram anticorpos citotóxicos circulantes. O fator causador do bloqueio parace não estar vinculado aos bloqueios de citotoxicidade "in vitro" e do teor de precepitinas do SAL.

Enzyme-linked immunosorbent spot assay analysis of peripheral blood lymphocyte reactivity to donor HLA-DR peptides: potential novel assay for prediction of outcomes for renal transplant recipients

Chronic allograft dysfunction, which is the most common cause of late allograft failure, is in part caused by an ongoing immune response orchestrated by T lymphocytes primed by the indirect pathway of allorecognition. The low frequencies of such T cells have made it difficult to study indirect alloreactivity by using currently available assays. The development of a sensitive, clinically useful method of measuring indirect alloreactivity among human renal transplant recipients was thus attempted. Furthermore, in a pilot immunologic study, the contribution of the indirect pathway was studied in two groups of renal transplant recipients, i.e., patients with no prior acute rejection episodes and stable renal function ("stable" patients) and patients with at least one previous episode of biopsy-proven acute rejection, who were thus at risk for the development of chronic rejection ("high-risk" patients). The frequencies of type 1 T helper (interferon-gamma-producing) and type 2 T helper (interleukin-5- and -10-producing) peripheral blood lymphocytes reactive with a panel of synthetic peptides (corresponding to sequences from donor HLA-DR molecules) were determined for renal transplant recipients and normal control subjects by using an enzyme-linked immunosorbent spot assay (ELISPOT). Among recipients of DR-mismatched allografts, a cut-off value of 60 interferon-gamma spots/10(6) cells significantly (P = 0.02) separated stable patients (creatinine concentration, 1.1 +/- 0.3 mg/dl) from high-risk patients (creatinine concentration, 2.3 +/- 1.7 mg/dl). This is the first demonstration that the enzyme-linked immunosorbent spot assay can be used to monitor indirect alloreactivity to donor HLA-DR peptides among renal transplant recipients. These data provide the rationale for the prospective study of indirect alloreactivity among transplant recipients, to allow predictions of which patients would be at risk for the development of chronic rejection and thus allow appropriate planning of future interventions.

Inflammation in lung transplantation for CF. Immunosuppression and modulation of inflammation

Lung transplantation is an accepted therapy for selected individuals with end-stage lung disease due to cystic fibrosis (CF). Recent data show that CF recipients of lung transplantation have survival as good as those of any other diagnostic group. After transplantation, CF patients confront the major threats to life and health of graft infection and rejection. Inflammation is the common mediator of injury to the lung in both these instances. Graft infection after lung transplantation involves the same micro-organisms as are typical with CF as well as opportunistic agents. Prophylactic strategies and aggressive diagnosis via bronchoscopy are both critical in the effective treatment of post-transplant lung infections. Graft rejection involves the detection and recognition of foreign antigen and the subsequent activation of specific T-lymphocyte clones leading to inflammatory injury to the donor organ. Immunosuppression is used to prevent and/or modulate host response to the donor organ and titrated to serum therapeutic drug monitoring and transbronchial biopsy findings. Precise clinical monitoring and aggressive diagnostic approaches are crucial to minimizing graft injury and enhancing life after transplantation. Although most CF lung transplant recipients experience both graft infection and rejection and the 5-yr survival rate remains at approx 50%, improvement in diagnosis and therapy continue over time. With the introduction of new approaches to antimicrobial therapy, new immunosuppressant agents and promising strategies to promote immune tolerance, survival after lung transplantation is likely to improve in the coming decades.