Mark L. Jordan

Tolerogenic immunosuppression for organ transplantation

BACKGROUND Insight into the mechanisms of organ engraftment and acquired tolerance has made it possible to facilitate these mechanisms, by tailoring the timing and dosage of immunosuppression in accordance with two therapeutic principles: recipient pretreatment, and minimum use of post-transplant immunosuppression. We aimed to apply these principles in recipients of renal and extrarenal organ transplants. METHODS 82 patients awaiting kidney, liver, pancreas, or intestinal transplantation were pretreated with about 5 mg/kg of a broadly reacting rabbit antithymocyte globulin during several hours. Post-transplant immunosuppression was restricted to tacrolimus unless additional drugs were needed to treat breakthrough rejection. After 4 months, patients on tacrolimus monotherapy were considered for dose-spacing to every other day or longer intervals. FINDINGS We frequently saw evidence of immune activation in graft biopsy samples, but unless this was associated with graft dysfunction or serious immune destruction, treatment usually was not intensified. Immunosuppression-related morbidity was virtually eliminated. 78 (95%) of 82 patients survived at 1 year and at 13-18 months. Graft survival was 73 (89%) of 82 at 1 year and 72 (88%) of 82 at 13-18 months. Of the 72 recipients with surviving grafts, 43 are on spaced doses of tacrolimus monotherapy: every other day (n=6), three times per week (11), twice per week (15), or once per week (11). INTERPRETATION The striking ability to wean immunosuppression in these recipients indicates variable induction of tolerance. The simple therapeutic principles are neither drug-specific nor organ-specific. Systematic application of these principles should allow improvements in quality of life and long-term survival after organ transplantation.

Human polyoma virus-associated interstitial nephritis in the allograft kidney

BACKGROUND Asymptomatic polyoma virus infection documented by urine cytology or serology is well known, but the clinical course of biopsy-proven interstitial nephritis is not well defined. METHODS Twenty-two cases were identified by histology, immunostaining, in situ hybridization, electron microscopy, or polymerase chain reaction. RESULTS The clinical features mimicked acute rejection (n=19), chronic rejection with incidental diagnosis at nephrectomy (n=2), or drug toxicity (n=1). Histology showed homogenous intranuclear inclusions. In situ hybridization showed BK virus (BKV) to be the predominant species, but polymerase chain reaction documented JC virus co-infection in one of five cases so tested. Electron microscopy in seven cases showed 20-51-nm virions. The two cases diagnosed at nephrectomy received no therapy. Initial antirejection therapy in 12 cases led to clearance of the virus in 1/12 (8%), partial therapeutic response in 3/12 (25%), and graft loss in 8/12 (67%) cases. The last recorded creatinine in patients with functional grafts ranged from 1.9 to 7.0 (median: 4.5) mg/dl, 0.4-45 (median: 4.0) months after initial diagnosis. The remaining eight cases treated by reduction of immunosuppression at the outset have been free of graft loss for 0.2-10.0 (median: 4.8) months since diagnosis, and clearance of virus has been documented in three of six (50%) cases. The serum creatinine in these patients is 1.7-6.0 (median: 2.4) mg/dl, 0.2-10 (median: 4.8) months after diagnosis. Follow-up biopsies performed 1-23.5 months after diagnosis show chronic allograft nephropathy. CONCLUSIONS Polyoma virus tubulo-interstitial nephritis-associated graft dysfunction usually calls for judicious decrease in immunosuppression and monitoring for acute rejection. Development of methods to serially quantify the viral load in individual patients could potentially improve clinical outcome.

Bone marrow augmentation of donor-cell chimerism in kidney, liver, heart, and pancreas islet transplantation

We have previously postulated that donor cell chimerism in organ transplantation is needed to attain a tolerant state. Here we show that donor cell chimerism can be augmented in organ recipients if they are infused perioperatively with 3 x 10(8) per kg of unmodified donor bone marrow cells and are kept on a conventional immunosuppressive regimen of tacrolimus (FK506) and prednisolone. 36 patients took part, of whom the first 18 patients have good transplanted kidney (n = 10), liver (n = 7), and heart (n = 7) function when followed up between 4 and 16 months. All patients are well. We found persistent multilineage leucocyte chimerism in blood of 17 recipients by flow cytometry and PCR techniques to detect donor alleles or Y chromosomes in female recipients of male organs. The use of the 5-antigben HLA matched same sex donor precluded detection of chimerism in one patient.

Endogenous nitric oxide inhibits the synthesis of cyclooxygenase products and interleukin-6 by rat Kupffer cells

Macrophage production of nitric oxide (N=O) leads to considerable alterations of vital metabolic pathways in various target cells. The present study tested whether N=O synthesis by Kupffer cells (KCs), the resident macrophages of the liver, interferes with the secretory function of these cells. As in other macrophage‐ type cells, the combination of lipopolysaccharide (LPS) and interferon‐γ (IFN‐γ) was a potent stimulus of N=O synthesis by KC. Treatment with LPS and IFN‐γ also induced significant production of prostaglandin E2 (PGE2), thromboxane B2 (TBX2), tumor necrosis factor a (TNF‐ α), interleukin‐1 (IL‐1), and IL‐6. Inhibition of N=O synthesis by the L‐arginine analogue NG‐monomethyl‐L‐ar‐ ginine (NMA) resulted in a further increase of PGEs, TXBs, and EL‐6 but not BL‐l and TNF‐α production, indicating specific inhibitory effects of endogenous N=O synthesis on the secretory activity of KCs. PGE2 production was most sensitive to the suppressive effect of N=O and increased 24 h after stimulation with LPS and IFN‐γ from 16.3 ± 4.9 ng/106 KCs without NMA to 94.3 ± 17.9 ng/106 KCs with NMA. This effect of NMA was reversed by a 10‐fold increase of the L‐arginine concentration. No recovery of PGE2 production was seen when N=O synthesis was blocked after 24 h. NMA treatment increased cyclooxygenase activity more than threefold, suggesting that N=O inhibits PGE2 and TXB2 production through diminished PGH2 availability. N=O synthesis did not significantly affect total protein synthesis or viability of the KCs. These results show that N=O influences the production of specific inflammatory mediators by KCs./

The histopathological changes associated with allograft rejection and drug toxicity in renal transplant recipients maintained on FK506. Clinical significance and comparison with cyclosporine.

The histopathological changes in 51 renal allograft biopsies from patients immunosuppressed with FK506 were compared with those seen in 30 needle biopsies obtained from patients on cyclosporine. The frequency and severity of rejection episodes were similar in both groups. Tubular vacuolation and myocyte vacuolation were found to be useful morphological markers to monitor short-term drug toxicity associated with both drugs. Long-term administration of FK506 led to striped interstitial fibrosis and arteriolar hyalinosis, similar to that previously documented for cyclosporine. One case each of hemolytic uremic syndrome and necrotizing arteriopathy was noted in patients receiving FK506. FK506 and cyclosporine are structurally unrelated compounds; hence the parallelism observed in their nephrotoxicity profile suggests that the interactions of these drugs with renal tissue involves the operation of two different initial signal-transducing mechanisms, ultimately activating the same final metabolic pathways.

INTERFERON-α-INDUCED ACUTE RENAL ALLOGRAFT REJECTION

The immunomodulating effects of interferons have led to their use in the treatment of a variety of illnesses, including cancer (1), and virally mediated infections, such as hepatitis (2). In addition, IFN has been given to immunosuppressed patients in an attempt to reconstitute the immune response to prevent viral infections such as CMV and herpes Simplex (3). Since CMV and viral hepatitis are potentially serious complications of renal transplantation (3, 4), the use of IFN for prophylaxis or treatment has been advocated in this setting. However, the potential effects of giving an immuno-modulator such as IFN to immunosuppressed transplant patients raises theoretical concerns about activation of immune responses and an increased risk of allograft rejection. Current immunosuppressive regimes for renal transplantation include CsA or FK506 in combination with steroids and sometimes AZA. While the mechanisms of action of CsA and FK506 are not completely understood, these agents appear to inhibit T cell activation through binding to specific binding cellular proteins (immunophilins), thereby altering intracellular signaling pathways and ultimately inhibiting expression of IL-2 and other cytokines (5). Both CsA (6) and FK506 (7) may inhibit IFN production, and low levels of circulating IFN-α have been described in renal transplant recipients (8). Although IFN modulate the immune response-both at the level of T cell activation (9) and antigen expression (10), the exact roles of these compounds in the immunosuppressive action of CsA and FK506 are not known. A number of studies have claimed efficacy of IFN-α preparations in the treatment of chronic persistent hepatitis (2) and trials of IFN preparations for viral prophylaxis in renal transplant recipients have been reported (3, 11, 12). The results of such trials suggested a benefit of prophylaxis for viral infections (3, 11), but, at times, at the expense of increased rejection (12). The complex issues involved in using IFN to treat hepatitis in a transplanted, immunosuppressed population prompted us to review our experience with IFN-α treatment in renal transplant patients.

POSTTRANSPLANT LYMPHOPROLIFERATIVE DISORDERS IN ADULT AND PEDIATRIC RENAL TRANSPLANT PATIENTS RECEIVING TACROLIMUS-BASED IMMUNOSUPPRESSION

Between March 27, 1989 and December 31, 1997, 1316 kidney transplantations alone were performed under tacrolimus-based immunosuppression at our center. Posttransplant lymphoproliferative disorders (PTLD) developed in 25 (1.9%) cases; the incidence in adults was 1.2% (15/1217), whereas in pediatric patients it was 10.1% (10/99; P<.0001). PTLD was diagnosed 21.0+/-22.5 months after transplantation, 25.0+/-24.7 months in adults and 14.4+/-18.2 months in pediatric patients. Of the 4 adult cases in whom both the donor and recipient Epstein Barr virus (EBV) serologies were known, 2 (50%) were seropositive donor --> seronegative recipient. Of 7 pediatric cases in whom both the donor and recipient EBV serologies were known, 6 (86%) were EBV seropositive donor --> seronegative recipient. Acute rejection was observed before the diagnosis of PTLD in 8 (53%) of 15 adults and 3 (30%) of 10 pediatric patients. Initial treatment of PTLD included a marked decrease or cessation of immunosuppression with concomitant ganciclovir therapy; two adults and two pediatric patients required chemotherapy. With a mean follow-up of 24.9+/-30.1 months after transplantation, the 1- and 5-year actuarial patient and graft survival rates in adults were 93% and 86%, and 80% and 60%, respectively. Two adults died, 3.7 and 46.2 months after transplantation, of complications related to PTLD, and 10 (including the 2 deaths) lost their allograft 3.7-84.7 months after transplantation. In children, the 1- and 5-year actuarial patient and graft survival rates were 100% and 100%, and 100% and 89%, respectively. No child died; one child lost his allograft 41.3 months after transplantation. One child had presumed recurrent PTLD that responded to discontinuation of tacrolimus and reinitiation of antiviral therapy. The mean serum creatinine level in adults was 2.5+/-1.2 mg/dl, and in children, it was 1.3+/-0.6 mg/ dl. Under tacrolimus-based immunosuppression, PTLD is less common after renal transplantation in adults than in children, but PTLD in children is associated with more favorable outcomes than in adults.

FK506 Rescue for resistant rejection of renal allografts under primary cyclosporine immunosuppression

Seventy-seven patients with ongoing acute rejection on initial CsA therapy were converted to FK506 to attempt graft salvage. Fifty-nine patients had undergone primary transplantation and 18 had been retransplanted; there were 52 cadaveric and 25 living-donor transplants. The indications for conversion to FK506 were ongoing, biopsy-confirmed rejection in all patients, including vascular rejection in 20. The median interval to rescue was 2 months (range 2 weeks to 36 months) after transplantation. Sixty-one of the 77 patients (79%) had already received one or more courses of an antilymphocyte preparation (OKT3: n=33; ALG or ATG: n=1; OKT3+ALG/ATG: n=27). Of the 77 patients, 57 (74%) have been successfully rescued and still have functioning grafts with a mean follow-up of 14 months, with a mean serum creatinine of 2.35±0.97 mg/dl. Eighteen patients were already dialysis-dependent at the time of conversion to FK506; of these, 9 (50%) were successfully salvaged and have a mean serum creatinine of 2.3 mg/dl. Of the 61 patients previously treated with antilymphocyte preparations, 48 (79%) were rescued. In those salvaged, prednisone doses have been lowered from 22.2±7.2 mg/day preconversion to 7.5±5.6 mg/day postconversion, and 12 patients are on FK506 monotherapy. In nondiabetics, mean serum glucose was 101.4±20.5 mg/dl preconversion and 93.2±22 postconversion (P=0.07), uric acid 7.3±2.3 and 7.1±1.5 mg/dl (P=0.53), and triglycerides 199.2±101.6 and 167.2±106.4 mg/dl (P=0.06). Cholesterol levels were significantly lower following FK conversion (207.7±46.5 mg/dl pre. vs. 188.3±39.7 post, P=0.007). FK506 is capable of salvaging renal allografts with ongoing acute rejection on CsA therapy, even when antilymphocyte preparations have been ineffective.

Biopsy of marginal donor kidneys: correlation of histologic findings with graft dysfunction.

BACKGROUND Kidney biopsies are being used to evaluate marginal donors, but rigorous statistical validation of this practice with multivariate analysis has not been performed. METHODS To analyze histologic parameters in 78 donor biopsies for their ability to predict graft dysfunction, we used a proportional odds model that included both donor and recipient factors. Glomerulosclerosis was categorized into grades 0, 1, 2, and 3, corresponding to 0, 1-10%, 11-20%, and 21-30% global sclerosis, respectively. The degrees of interstitial fibrosis, tubular atrophy, arteriosclerosis, and arteriolar hyalinosis were graded from 0 to 3+, using definitions suggested by the Banff Schema of allograft pathology. RESULTS Increasing donor age was associated with higher glomerulosclerosis, tubular atrophy, and arteriosclerosis. Kidneys with any degree of interstitial fibrosis were 2.6 times [odds ratio (OR)] more likely to experience a worse outcome at 6 months (P = 0.02). This association held up after correction for acute rejection (OR 2.5, P = 0.03) and high panel-reactive antibody (OR 3.4, P = 0.006), However, the OR was reduced to 1.9 (P = 0.15) after controlling for recipient age. With each increment in the grade of glomerulosclerosis, the odds for a worse outcome at 12 months increased to 2.3 (P = 0.005). The value for OR became 2.0 (P = 0.03) when controlling for recipient age (P = 0.01), 2.4 (P = 0.005), when controlling for acute rejection, and 2.3 (P = 0.006) when controlling for high panel-reactive antibody. CONCLUSIONS Histopathological parameters present in donor biopsies can independently predict post-transplant graft function. Implications for the pool of donor organs available for transplantation are discussed.

Renal Transplantation In Recipients Over The Age Of 60: The Impact of Donor Age

BACKGROUND Kidneys from older donors exhibit a series of changes characterized by glomerular, vascular, and tubular senescence. These changes may be aggravated by atherosclerosis, hypertension, or diabetes, which are highly prevalent in older individuals. METHODS We analyzed the outcome after transplantation in 230 recipients over the age of 60, who received transplants between February 1990 and December 1996. We assessed the 1- and 5-year patient and graft survival, the quality of renal function, tacrolimus levels, the incidence of rejection, and the incidence of delayed graft function, and compared the outcomes in recipients of kidneys from donors over the age of 60 (group 1, n = 40) with those in recipients of kidneys from donors under the age of 60 (group 2, n = 190). There were no differences between the two groups in terms of recipient sex, race, age, and cold ischemia time. Immunosuppression was with tacrolimus and steroids in 61% of cases; in the remainder of the patients, a third agent, either azathioprine, cyclophosphamide (for 1 week), or mycophenolate mofetil was administered as well. The median follow-up was 31.5 months (range: 1-86). RESULTS In recipients over the age of 60 receiving tacrolimus-based immunosuppression, overall patient survival at 1 and 5 years was 90% and 76%, and was not significantly compromised in recipients receiving a kidney from a donor over the age of 60. The overall 1-and 5-year actuarial graft survival was 84% and 64%; in recipients from donors over the age of 60, it was 73% and 52%, whereas in recipients of kidneys from donors under the age of 60, it was 87% and 66% (P<0.05). Most of the effect on graft survival was seen by 1 year. The mean serum creatinine was 2.6+/-2.7 mg/dl, without any difference between the two groups. Although the incidence of delayed graft function was higher in recipients of kidneys from donors over the age of 60, this difference did not reach statistical significance. CONCLUSIONS Although the overall outcomes of transplantation in older recipients remain reasonable, the inferior outcomes with older donor kidneys call into question proposals to utilize older donor kidneys preferentially in older recipients.