Relationship between chimerism and tolerance in a kidney transplantation model

The persistence of donor leukocytes in recipients of organ allografts has been associated with long-term graft acceptance. However, it remains unclear whether this peripheral donor cell microchimerism plays an active role in graft acceptance or is simply a consequence of the maintenance of sufficient immunosuppression to avoid rejection. A model of kidney transplantation between swine leukocyte Ag (SLA)-matched miniature swine, in which tolerance can be established with or without immunosuppressive treatment, has been used to study the correlation between donor leukocyte chimerism and kidney graft acceptance. SLA-identical kidney transplants were performed from animals positive for an allelic pig leukocyte Ag to animals negative for this marker. SLA-identical kidney transplant recipients given a 12-day course of cyclosporine (CyA) (n = 3) became tolerant, showing stable serum creatinine levels (1-2 mg/dl) after cessation of CyA treatment. Donor cell chimerism (0.2-0.7%) was present by FACS in all three animals with peak levels detected at 3 wk. Two control animals receiving SLA-identical kidney grafts without CyA also showed stable serum creatinine levels and became tolerant. However, in neither of these animals could donor leukocytes be detected in the peripheral blood beyond 1 wk following transplantation. In one additional control animal, ureteral obstruction occurred at day 10, and was associated with additional peripheral chimerism, presumably related to inflammation rather than to immune status. These results indicate that the persistence of donor cell chimerism is not a requirement for the maintenance of tolerance to organ allografts in this model.     

Leucopenia Associated with Trimethoprim-Sulphamethoxazole after Renal Transplantation

Four patients who had received cadaveric renal allografts developed a profound and sustained leucopenia in association with a trimethoprim-sulphamethoxazole preparation. Ten other cadaveric renal allograft recipients received identical chemotherapy with no adverse effects. Statistical analysis showed that the association of leucopenia and trimethoprim-sulphamethoxazole therapy was dependent on the time after the transplantation procedure and was not related to the dosage of immunosuppressive chemotherapy or renal function.     

Clinical aspects of polycystic disease of the kidneys.

Seventy-eight patients were treated for polycystic disease of the kidneys. An analysis of the interval between the onset of symptoms and end-stage renal failure made it possible to give and accurate prognosis in individual cases. Pregnancy and urinary infection did not appear to accelerate deterioration of renal function, but Rovsing'' operation precipitated renal failure in some cases. Forty-two patients needed replacement treatment for end-stage renal failure, and 24 patients received 29 renal allografts. Transplant function at all times was better than a matched group of 70 patients indications for removal of polycystic kidneys in graft recipients were persistnet or recurrent infection, erythraemia that failed to respond to conservative treatment, and to make room for the transplant.     

Cyclosporine A and purinergic receptors in rat kidney

Previous reports have demonstrated that Cyclosporine A (CyA) chronically administered induces an increase in adenosine plasma concentration by inhibiting adenosine uptake by red blood cells (RBC). We hypothesized that this effect may modulate, by a down regulation, the mRNA expression of adenosine receptors in rat kidney. Since high blood pressure (HBP) is a classical side effect of CyA treatment, nicardipine, a dihydropyridine calcium channel blocker, is often associated with CyA in treatment. To distinguish between the effects of CyA-induced HBP and the effects of CyA by itself, we have evaluated the effects of CyA and/or nicardipine on the mRNA expression of A1 and A2a adenosine receptors. The study was performed on five groups of rats (n= 8) receiving during 21 days either serum saline (0.5 ml i.p), CyA (12 mg/kg/day, i.p), nicardipine (1.2 mg/kg i.p) or nicardipine + CyA. The last (or fifth) group was injected with vehicle (0.5 ml i.p). Blood samples for adenosine assay were collected in the renal artery at day 21, just before the rat kidneys were removed for quantitation of adenosine A1 and A2a mRNA concentration by RT-PCR. We make two conclusions :i) Nicardipine induces a decrease in mRNA expression of A1 but not of A2a adenosine receptors. However, because nicardipine lowered both blood pressure and A1 mRNA expression, it is not possible to conclude if A1 mRNA decrease is implicated in the nicardipine effects on blood pressure.ii) CyA induces an increase in renal artery adenosine concentration and a decrease in mRNA expression of A1 and A2a adenosine receptors.     

Cyclosporin A: a powerful immunosuppressant.

Cyclosporin A (CyA) is a powerful immunosuppressive agent whose lack of myelotoxicity makes it unique among nonsteroidal drugs currently given for immunosuppression. It has been used with initial success in recipients of kidney, liver, bone marrow and pancreas transplants, and it may also have clinical application in the treatment of autoimmune disorders. In regard to its use in transplant recipients, there are many remaining questions about its mechanism of action, the optimum dose, whether it should be used alone or with other immunosuppressants, whether it can suppress chronic rejection and what its long-term side effects may be. These questions can only be answered by further careful laboratory investigation and controlled clinical trials. Until then, CyA should only be administered in centres experienced in its use.     

Pharmacokinetic conversion study of a new cyclosporine formulation in stable adult renal transplant recipients

Cyclosporine A (CyA) is a standard component of immunosuppressive regimens. It is a critical-dose drug for which a minor change in absorption can have important clinical consequences. The aim of the study was to compare the pharmacokinetics and safety of the new generic CyA formulation, Equoral capsules, after a switch from original formulation, Neoral capsules, in seventy stable adult renal transplant recipients. The extent and rate of pharmacokinetic parameters for bioequivalence were compared in a non-randomized, steady-state clinical study with fixed non-replicate study design. Pharmacokinetic analysis of CyA have shown that both the rate and extent of absorption of Equoral does not differ significantly from that of Neoral. At identical dosing, the new formulation was found to have geometric means of C(max) 717 ng/ml and AUCtau 3108 ng/ml.h, while corresponding results of comparator were 725 ng/ml and AUCtau 3039 ng/ml.h, respectively. The 90 % confidence intervals of C(max) and AUCtau were within 80- 125 % interval of the mean values. The results suggest that Equoral capsules can be used as an alternative treatment to Neoral capsules in CyA regimen.     

Thromboxane receptor blockade improves cyclosporine nephrotoxicity in rats

Cyclosporine A (CyA) nephrotoxicity is associated with impaired renal hemodynamic function and increased production of the vasoconstrictor eicosanoid thromboxane A2 (TxA2). In CyA toxic rats, renal dysfunction can be partially reversed by inhibitors of thromboxane synthase. However, interpretation of these results is complicated since inhibition of thromboxane synthase may cause accumulation of prostaglandin endoperoxides that can act as partial agonists at the TxA2 receptor and may blunt the efficacy of treatment. Furthermore, these endoperoxides may be used as substrate for production of vasodilator prostaglandins causing beneficial effects on hemodynamics which are independent of thromboxane inhibition. To more specifically examine the role of TxA2 in CyA toxicity, we investigated the effects of the thromboxane receptor antagonist GR32191 on renal hemodynamics in a rat model of CyA nephrotoxicity. In this model, administration of CyA resulted in a significant decrease in glomerular filtration rate (GFR) (2.85 +/- 0.26 [CyA] vs 6.82 +/- 0.96 ml/min/kg [vehicle]; p less than 0.0005) and renal blood flow (RBF) (21.65 +/- 2.31 [CyA] vs 31.87 +/- 3.60 ml/min/kg [vehicle]; p less than 0.025). Renal vascular resistance (RVR) was significantly higher in rats given CyA compared to animals treated with CyA vehicle (5.32 +/- 0.55 [CyA] vs. 3.54 +/- 0.24 mm Hg/min/ml/kg [vehicle]; p less than 0.05). These renal hemodynamic alterations were associated with a significant increase in urinary excretion of unmetabolized, "native" thromboxane B2 (TxB2) (103 +/- 18 [CyA] vs 60 +/- 16 pg/hour [vehicle]; p less than 0.05). Only minimal histomorphologic changes were apparent by light microscopic examination of kidneys from both CyA and vehicle treated animals. However, with immunoperoxidase staining, a significantly greater number of cells expressing the rat common leukocyte antigen was found in the renal interstitium of rats given CyA. There was no detectable increase in monocytes/macrophages in the kidneys of CyA toxic animals. In rats treated with CyA, intraarterial infusion of GR32191 at maximally tolerated doses significantly increased GFR and RBF, and decreased RVR. Although both RBF and RVR were restored to levels not different from controls, GFR remained significantly reduced following administration of GR32191. These data suggest that the potent vasoconstrictor TxA2 plays an important role in mediating renal dysfunction in CyA nephrotoxicity. However, other factors may be important in producing nephrotoxicity associated with CyA.     

Thromboxane receptor blockade improves cyclosporine nephrotoxicity in rats

Cyclosporine A (CyA) nephorotoxicity is associated with impaired renal hemodynamic funtion and increased production of the vasoconstrictor eicosanoid thromboxane A₂ (TxA₂). In CyA toxic rats, renal dysfunction cna be partially reversed by inhibitors of thromoboxane sysnthase. However, interpretation of these results is complicated since inhibitance of thromboxane synthase may cause accumulation of prostaglandin endoperoxides that can act as partial agonists at the TxA₂ receptor and may blunt the efficacy of treatment. Furthermore, these endoperoxides may be used as substrate for production of vasodilator prostaglandins causing beneficial effects on hemodynamics which are independent of thromboxane inhibition. To more specially examine the role of TxA₂ in CyA toxicity, we investigated the effects of the thromboxane receptor antagonist GR32191 on renal hemodynamics in a rat model of CyA nephrotoxicity. In this model, administration of CyA resulted in a significant decrease in glomerular filtration rate (GFR) 2.85±0.26 [CyA] vs 6.82±0.96 ml/min/kg [vehicle]; p<0.0005) and renal blood flow (RBF) (21.6±2.31 [CyA] vs 31.8±3.60 ml/min/kg [vehicle]; p<0.025). Renal vascular resistance (RVR) was significantly higher in rats given CyA compared to animals treated with CyA vehicle (5.32±0.55 [cyCyA] vs 3.54±0.24 mm Hg/min/ml/kg [vehicle]; p<0.05). These hemodynamic alterations were associated with a significant increase in urinary excretion of unmetabolized, “native” thromboxane B₂ (TxB₂ (103±18 [CyA] vs 60±16 pg/hour [vehicle]; p<0.05). Only minimal histomorphologic changes were apparent by light microscopic examination of kidneys from both CyA and vehicle treated animals. However, with immunoperoxidase staining, a significantly greater number of cells experssing the rat common leukocyte antigen was found in the renal interstitium of rats given CyA^*. There was no detectable increase in monocytes/macrophages in the kidneys of CyA toxic animals. In rats treated with CyA, intraarterial infusion of GR32191 at maximally tolerated doses significanlty increased GFR and RBD, and decreased RVR. Although both RBF and RVR were restored to levels not different from controls, GFR remained significantly reduced following administration of GR32191. These data suggest that the potent vasoconstrictor TxA₂ plays an important role in mediating renal dysfunction in CyA nephrotoxicity. However, other factors may be important in producing nephrotoxicity associated with CyA.     

Comparison of the efficacy and safety of Consupren solution and Sandimmun Neoral solution, 50 ml in stable heart transplant patients

Cyclosporine A (CyA) is a standard component of immunosuppressive regimen after heart transplantation in most centres. The widespread clinical use of cyclosporine-based immunosuppressive regimens since 1983 has led to significant improvements in the survival of cardiac allograft recipients due to decreased mortality from infections and rejections. (1-3) CyA has been shown to be safe and effective. Owing to its success when used after the heart transplantation the number of patients has also risen. This caused growing financial demands on health insurance companies in the Czech Republic where the immunosuppressive drugs are fully reimbursed. A prospective randomized study in 11 stable heart transplant patients was performed to compare the efficacy and safety of Consupren (IVAX-CR) a Sandimmun Neoral (Novartis) solution based immunosuppressive regimen. The results suggest that Consupren solution can be used as an alternative treatment to Sandimmun Neoral in CyA based regimen.     

Murine renal allografts: spontaneous acceptance is associated with regulated T cell-mediated immunity.

It was shown >20 yr ago that mice will spontaneously accept renal allografts in the absence of immunosuppression, but the mechanism responsible for this is not understood. We transplanted DBA/2 (H-2(d)) kidneys into nephrectomized C57BL/6 (H-2(b)) mice, and the allografts were spontaneously accepted for >60 days without immunosuppression. In contrast, nonimmunosuppressed cardiac and skin allografts in the same strain combination are rejected within approximately 10 days. The accepted renal allografts have a prominent leukocytic infiltrate, suggesting an ongoing, local immune response. At 60 days post-transplant, the recipients of accepted renal allografts display DBA/2-reactive alloantibodies. They also display DBA/2-reactive delayed-type hypersensitivity responses that are actively counter-regulated by DBA/2-induced TGF-beta production, but not by IL-10 production. These data suggest that a donor-reactive, cell-mediated immune mechanism involving TGF-beta is associated with the spontaneous acceptance of renal allografts in mice.     

Blood transfusion and renal allograft survival.

Thirty-two first renal transplantations with cadaveric allografts were reviewed to see how many of the recipients had received blood transfusions preoperatively. There was a significant difference in transplant survival between patients who had and patients who had not received blood transfusion before transplantation; this difference was entirely due to acute rejection within three months after transplantation in patients who had not received transfusion. Other factors studied had no effect on survival.     

Prolongation of canine pancreas allograft survival with cyclosporin A: preliminary report.

Studies were conducted on dogs to test the efficacy of cyclosporin A (CyA) in prolonging normoglycaemia and graft survival after whole-organ pancreas allograft transplantation. Five dogs subjected to pancreatectomy alone served as controls. Withholding immunosuppression after transplantation (five animals) resulted in the same median duration of survival as occurred in the controls (13 days). Azathioprine and steroids (seven animals) produced median durations of normoglycaemia and survival of 9 and 23 days respectively. Animals given CyA 18 mg/kg/day (five) and 25 mg/kg/day (10), however, showed median durations of normoglycaemia of 18 and 55 days (p less than 0.05 and p less than 0.02) respectively and median survival times of 36 and 85 days (NS and p less than 0.02). If CyA proved effective in controlling rejection of pancreas allografts in man it would offer unstable diabetics in renal failure a more hopeful outlook than conventional immunosuppression.     

Notes and queries

Abstract

We investigated the renal protective effects of phophodiesterase type 5 (PDE5) inhibitors in mice with cyclosporine A (CyA; a calcineurin phosphatase inhibitor) induced nephrotoxicity. Fifty male mice were divided into five groups of 10. Group 1 received no treatment, group 2 received only saline orally, group 3 received 30 mg/kg/day CyA by subcutaneous injection, group 4 received only 30 mg/kg/day vardenafil orally, and group 5 received 30 mg/kg/day CyA by subcutaneous injection and 30 mg/kg/day vardenafil orally. At 28 days, platelet-derived growth factor A (PDGF-A) and C (PDGF-C), transforming growth factor-beta 1 (TGF-β1), cyclo-oxygenase 1 and 2 (COX-1 and COX-2), and P glycoprotein (Pgp) expression levels were measured in the renal tissues. In addition, expressions of COX-1 and COX-2 genes were determined using real-time PCR. PDE5 inhibitor administration ameliorated decreased PDGF-A and C, TGF-β1, COX-1 and -2, and Pgp expression levels by modulation of cyclic guanosine monophosphate (cGMP) activity in kidneys. The relative expressions of COX-1 and COX-2 genes to GAPDH revealed that the maximum increase was obtained in the group treated with CyA and vardenafil for both COX-1 and COX-2 genes. Our study revealed that long term oral treatment with vardenafil protects kidneys from CyA induced nephrotoxicity. We showed that long term oral treatment with PDE5 prevents pathological kidney changes caused by CyA induced nephrotoxicity.     

Male Fertility in Uremia: Restoration by Renal Allografts

Spermatogenesis has been studied in eight chronic uremic patients on hemodialysis and in 11 recipients of well-functioning renal allografts. Sexual activity, semen analysis and testicular biopsy are abnormal in chronic uremic patients. Spermatogenesis remains “arrested” even when uremia is well controlled by intermittent hemodialysis. Marked improvement occurs in sexual performance, semen analysis and testicular biopsy after successful kidney transplantation. Immunosuppressive treatment, at dosages used six months after allografting, does not appear to affect male fertility adversely.     

Hyperparathyroidism after renal transplantation.

Renal transplantation reduced circulating parathyroid hormone in recipients of renal allografts. Nevertheless, biochemical and histological evidence of mild hyperparathyroidism persisted up to eight years after renal transplantation despite good graft function.     

T cell infiltration into class II MHC-disparate allografts and acute rejection is dependent on the IFN-gamma-induced chemokine Mig.

Direct evidence that cytokines with chemoattractant properties for leukocytes, chemokines, recruit alloantigen-primed T cells into transplanted allografts has been lacking. We present evidence that neutralization of a single chemokine inhibits T cell infiltration into class II MHC-disparate murine allografts and acute rejection. The chemokines IFN-gamma-inducible protein-10 and monokine induced by IFN-gamma (Mig) are expressed in allogeneic skin grafts during the late stages of acute rejection. Survival of class II MHC-disparate B6.H-2bm12 allografts is prolonged from day 14 to day 55 posttransplant when C57BL/6 recipients are given a short course treatment with an antiserum to Mig. This treatment also inhibits T cell and macrophage infiltration into the allografts. B6.H-2bm12 allografts are also not rejected by IFN-gamma-/- C57BL/6 recipients. Injection of Mig directly into B6.H-2bm12 grafts on IFN-gamma-deficient recipients restores T cell infiltration and rejection. Therefore, the inability of IFN-gamma-deficient recipients to reject the class II MHC-disparate allografts is due to the lack of intraallograft Mig production and alloantigen-primed T cell recruitment to the graft. These results indicate for the first time the potential utility of chemokine neutralization strategies in preventing T cell infiltration into allografts and abrogating acute rejection.     

HLA-DRw6 and renal allograft rejection.

HLA-DRw6-positive patients are "high responders" to certain renal allograft antigens. A study was therefore conducted of the outcome of 247 first renal allografts in 74 DRw6-positive and 173 DRw6-negative recipients. The effectiveness of matching for HLA-DR determinants in both groups was also analysed. The one-year graft survival in DRw6-positive patients was 59% as compared with 75% in DRw6-negative recipients (p = 0.012). A striking difference between the two groups was that HLA-DR matching significantly improved renal allograft survival only in the DRw6-positive patients. In those patients the one-year survival of HLA-DR-identical grafts was 95% as compared with only 38% for 2-DR mismatched grafts (p = 0.009). In DRw6-negative patients only a slight beneficial effect of HLA-DR matching was observed (83% versus 72% at one year for the 0-DR and 2-DR mismatched grafts, respectively) (p greater than 0.05). These findings are clear evidence that DRw6-positive patients (about a quarter of the patients on the waiting list of Eurotransplant) should be given HLA-DR-identical kidney transplants only.     

Long-term survival of human skin allografts in patients with immunosuppression

Severe burn patients lack adequate skin donor sites to resurface their burn wounds. Patients with severe burn injuries to areas such as an entire face are presently reconstructed with skin grafts that are inferior to normal facial skin. This study was designed in part to determine whether human skin allografts would survive, repopulate, and persist on patients with immunosuppression and after discontinuation of immunosuppression. Small split-thickness skin grafts were synchronously transplanted at the time of renal transplantation from six renal transplant donors to recipients. All six patients were immunosuppressed with the usual doses of renal transplant immunosuppressants (methylprednisolone, cyclosporine, prednisone, and azathioprine). The skin allografts were biopsied when rejection was suspected and at various intervals. Special histologic studies were performed on skin biopsy specimens. Class II DNA tissue typing was performed on transplanted and autogenous skin biopsy specimens of four patients. Fluorescent in situ hybridization was performed successfully on skin biopsies of four patients' transplanted skin and on two of these four patients' autogenous skin. All six human skin allografts sustained a 100 percent take and long-term clinical survival. DNA tissue typing performed on skin allograft biopsy specimens from patients taking immunosuppressants all revealed donor and recipient cells. DNA tissue typing performed on autogenous skin biopsies from the same patients all revealed only recipient cells. Fluorescent in situ hybridization performed on allograft and autogenous specimens from patients taking immunosuppressants revealed transplanted donor cells with rare recipient cells in the allograft and only recipient cells in the autogenous skin. This study of six patients proves that it is possible for human skin allografts to survive indefinitely on patients taking the usual dosages of immunosuppressants used for renal transplantation. There was minimal repopulation of skin allografts by autogenous keratinocytes and fibroblast while patients were taking immunosuppressants. Immunosuppression was discontinued in two patients after renal transplant rejection after 6 weeks and 5 years. When immunosuppression was discontinued after 5 years in one patient, the skin allograft cells were destroyed and replaced with autogenous cells, but the skin graft did not reject acutely and persisted clinically. It is hypothesized that the acellular portion of the skin allograft was not rejected acutely because of relatively low antigenicity and because it acted as a lattice for autogenous cells to migrate into and replace rejected allograft skin cells. No chimerism was seen in autogenous skin in the skin-renal transplant patients in this study.     

Cyclosporine A treatment in four cases of aplastic anemia

Cyclosporine A (CyA) treatment of 4 patients with severe aplastic anemia, who were ineligible for bone marrow transplantation, was carried out for periods of between 12 weeks to 20 months. A normalization of Hb and bone marrow, together with a marked improvement in WBC and platelet counts, were observed in only one of these four patients. The remission was maintained for 20 months under continuous treatment. A relapse occurred only when the patient himself interrupted treatment. No serious side effects were observed with CyA doses of 4-10 mg/kg/daily and blood concentrations of 200-400 ng/ml. No significant changes in T helper/T suppressor ratios were noted during the course of CyA treatment.     

GU evaluation and management of renal transplant candidates and recipients

There are more than 200,000 end stage renal disease (ESRD) patients who are potential transplant candidates and more than 100,000 previously transplanted renal recipients with functioning allografts in the United States. Fifty-seven percent of these patients are male and forty percent are greater than 50 years of age. Diabetes is the most common cause of kidney failure. It is evident that many patients are at high risk for development of urologic problems and thus it is estimated that the average urologist will care for up to ten of these patients yearly. Thus a review of the genitourinary (GU) evaluation and management of these patients is timely.