Long-term limb allograft survival using a short course of anti-CD45RB monoclonal antibody, LF 15-0195, and rapamycin in a mouse model

BACKGROUND: The purpose of this study was to determine if a short course of monoclonal antibody (mAb) against CD45RB, LF 15-0195, and rapamycin would achieve long-term survival by inducing tolerance in a mouse limb transplant model. METHODS: Group 1 (n=9) consisted of nine isogenic (C57BL/6) transplants. Group 2 (n=3) included C57BL/6-to-BALB/c transplants receiving no drug therapy. Group 3 mice (n=4) were treated with mAb (3 mg/kg) and LF (2 mg/kg), and Group 4 (n=13) was treated with mAb, LF, and rapamycin (2 mg/kg). Both treatment groups received drug treatment for only 14 days posttransplantation. Animals were sacrificed if they displayed evidence of rejection or when deemed to be tolerant (defined as >day 100). RESULTS: All isografts had normal histology and graft function on day 100. Untreated C57BL/6-to-BALB/c allografts developed acute rejection within 10 days. The combination of mAb and LF prolonged allograft survival to a mean of 39+/-7 days. In Group 4, two animals had to be sacrificed at days 28 and 76 due to acute urinary retention. Transplant tolerance was achieved in 8 of the remaining 11 animals with a mean survival time of 100+/-12 days. Donor specific tolerance was demonstrated through permanent acceptance of skin grafts from the donor strain and rejection of skin grafts from C3H mice. Three Group 4 animals showed clinical and histological signs of mild, chronic rejection. Dendritic cells isolated from tolerant recipients exerted a suppressive effect in mixed lymphocyte reaction. CONCLUSION: A short course of anti-CD45RB mAb and LF 15-0195 prolonged limb allograft survival. The addition of rapamycin induced limb allograft tolerance which is associated with the generation of tolerogenic dendritic cells that suppressed T-cell proliferation.     

Intragraft delivery of 16, 16-dimethyl PGE2 induces donor-specific tolerance in rat cardiac allograft recipients

The stable prostaglandin E2 analogue, 16,16-dimethyl PGE2 (di-M-PGE2) was continuously infused by osmotic pump directly into rat heterotopic cardiac allografts. Intragraft delivery of 20 micrograms/kg/day di-M-PGE2 for 2 weeks completely prevented graft rejection for more than 150 days (n = 10), while untreated Buffalo recipients rejected Lewis cardiac allografts within 8 days after transplantation (mean survival time = 7.4 +/- 0.5 days, n = 5). When given for only 1 week, 20 micrograms/kg/day had a partial effect, since 60% of recipients accepted grafts long-term and 40% experienced rejection by day 14 (n = 5). In contrast, systemic intravenous administration of 20 micrograms/kg/day di-M-PGE2 for 2 weeks could not prolong graft survival (MST = 7.0 +/- 0.0 days, n = 3), and the higher dose of 200 micrograms/kg/day resulted in death by day 2 (n = 5). Long-term BUF recipients of LEW cardiac allografts accepted LEW donor strain skin grafts for more than 35 days while rejecting third-party Wistar Furth skin grafts in a normal fashion (MST = 7.3 +/- 0.5 days, n = 3), indicating the induction of donor-specific tolerance. Long-surviving LEW cardiac allografts retransplanted into naive BUF recipients were rejected within 7 days (MST = 6.7 +/- 0.5 days, n = 3), indicating no change in graft immunogenicity. Therefore, a 14-day infusion of di-M-PGE2 directly into a strongly MHC-mismatched cardiac allograft uniformly has resulted in long-term engraftment and the development of recipient donor-specific tolerance.     

The effects of cyclosporine on varying segments of small-bowel grafts in the rat

The relationship between the cyclosporine A (CSA) dose and rejection of varying lengths of small-bowel grafts was studied in a rat heterotopic microsurgical small-bowel transplantation model involving a haploidentical strain combination. When Lewis X Brown Norway F1 hybrid (LBN) small-bowel grafts were transplanted into Lewis (LEW) rats without CSA, all grafts in the proximal 10 cm, the proximal 40 cm, and the entire (approximately 80 cm) small bowel were rejected on days (mean +/- SEM) 6.6 +/- 0.2 (n = 11), 7.0 +/- 0.4 (n = 6), and 7.8 +/- 0.7 (n = 6), respectively. A 10-day course (days 0-9) of CSA 2 mg/kg significantly (p less than 0.05) prolonged the survival of the proximal 10 cm, the proximal 40 cm, and the entire small bowel allografts to days 18.8 +/- 1.7 (n = 5), 16.5 +2- 1.3 (n = 6), and 13.5 +/- 1.0 (n = 4), respectively. Similarly, the CSA 5 mg/kg regimen significantly (p less than 0.05) delayed the rejection of the 10 cm, the 40 cm, and the 80 cm small-bowel grafts to days 50.2 +/- 7.2 (n = 6), 47.7 +/- 2.6 (n = 3), and 40.3 +/- 5.8 (n = 3), respectively. However, 6 of 12 rats treated with CSA 5 mg/kg died of pneumonia, and these animals were all in groups with the 40 cm and 80 cm grafts. When these animals were included in calculations of rejection-free survival, the averages for the 40 and 80 cm groups treated with CSA 5 mg/kg were 34.2 +/- 6.4 and 28.7 +/- 6.1 days, respectively. CSA suppressed rejection of small-bowel allografts in a dose-related fashion. More important, significantly (p less than 0.05) lower doses of CSA were necessary for rats that received shorter intestinal grafts. In fact, the relationship between rejection and CSA dose in the 10 cm grafts was characterized by the formula: day of rejection = 9.3 [CSA dose]1.03. We conclude that the ideal small intestinal graft should be the smallest possible segment that maintains adequate nutrition and CSA doses should be matched for segment lengths.     

Evidence that cyclosporine prevents rejection and recurrent diabetes in pancreatic transplants in the BB rat

Cyclosporine prevents the development of diabetes in spontaneously diabetic BB rats and NOD mice. However, islet transplants have been shown to be subject to immunologic destruction in hosts treated with CsA and anti-CD4 antibody or those rendered tolerant to donor antigens. This study determines whether the minimum dose of CsA necessary to prevent rejection of pancreatic transplants will also prevent recurrent diabetes in pancreas transplants in BB rats. Lewis recipients promptly reject BN (n = 13, MST 9.2 +/- 0.7 days) and Fisher (n = 6, MST = 11.3 +/- 0.8 days) pancreatic transplants. Treatment with CsA 5 mg/kg/day 0-50 days posttransplant and 2 mg/kg/day 51-100 days (low-dose CsA) produced indefinite survival of BN (n = 5) but not Fisher (n = 4) allografts. Fisher allografts were uniformly successful if maintained on 5 mg/kg/day (n = 4). Treatment with CsA 5 mg/kg/day for 14 days had no deleterious effect on glucose tolerance in Lewis isografts (control [K = 1.81 +/- 0.24, n = 8] vs. CsA treated [K = 1.76 +/- 0.20, n = 8, P = NS]). Low-dose CsA ensured permanent survival of MHC-compatible WF (n = 7, MST greater than 115 days) and MHC-incompatible BN (n = 9, MST greater than 117 days, P = NS) pancreatic transplants in spontaneously diabetic BB/Wor hosts. Three of 11 recipients surviving greater than 100 days enjoyed seemingly permanent acceptance of their allografts after discontinuation of CsA. Immunocompetence was demonstrated by rejection of their pancreas transplants when challenged with donor skin. Vascularized pancreatic allografts treated with CsA appear to be less vulnerable to recurrent diabetes than are islet transplants. Low-dose CsA protects vascularized pancreatic allografts in BB rats from both rejection and recurrent diabetes.     

Limb allografts in rats immunosuppressed with FK506. I. Reversal of rejection and indefinite survival

We have tested the effects of FK506 (FK), a new immunosuppressive agent, on a rat limb allograft model. Histoincompatible BN limb allografts were rejected in untreated F344 hosts within 11 +/- 1 days (mean +/- SD) after operation. A single injection of 2 mg/kg, 10 mg/kg, or 50 mg/kg of FK on the day of limb transplantation (day 0) significantly prolonged graft survival in a dose-dependent manner--i.e., mean limb survival times (MST) based on gross signs of skin rejection were 16 +/- 3 days, 51 +/- 6 days, or 104 +/- 17 days, respectively (P less than 0.01). Delayed treatment with a single injection of 10 mg/kg of FK at when early signs of rejection were visible (day 7 or day 10) reversed the ongoing rejection. The MSTs in these groups were comparable to that of those treated with the same dosage of FK on day 0. The FK-induced unresponsiveness toward limb allografts was donor-specific because limb-allografted. FK-protected rats could not accept the skin grafts from a third-party donor. In the next set of experiments, rats were given a single administration of 10 mg/kg of FK on the day of limb allograft, followed by intermittent injections of 3 mg/kg of FK once a week. This regimen produced complete graft survival for more than 200 days, though Pneumocystis carinii pneumonia occurred in most of the recipients. These results represent the unique effects of FK in preventing or reversing the graft rejection and in inducing indefinite survival in this animal model of composite tissue allografts.     

Blockade of Macrophage Colony-Stimulating Factor Reduces Macrophage Proliferation and Accumulation in Renal Allograft Rejection

Macrophage accumulation within an acutely rejecting allograft occurs by recruitment and local proliferation. To determine the importance of M-CSF in driving macrophage proliferation during acute rejection, we blocked the M-CSF receptor, c-fms, in a mouse model of acute renal allograft rejection. C57BL/6 mouse kidneys (allografts, n = 20) or BALB/c kidneys (isografts, n = 5) were transplanted into BALB/c mice. Anti-c-fms antibody (AFS98) or control Ig (50 mg/kg/day, i.p.) was given daily to allografts from days 0-5. All mice were killed day 6 postoperatively. Expression of the M-CSF receptor, c-fms, was restricted to infiltrating CD68+ macrophages. Blockade of c-fms reduced proliferating (CD68+/BrdU+) macrophages by 82% (1.1 v 6.2%, p < 0.001), interstitial CD68+ macrophage accumulation by 53% (595 v 1270/mm2, p < 0.001), and glomerular CD68+ macrophage accumulation by 71% (0.73 V 2.48 CD68+ cells per glomerulus, p < 0.001). Parameters of T-cell involvement (intragraft CD4+, CD8+ and CD25+ lymphocyte numbers) were not affected. The severity of tubulointerstitial rejection was reduced in the treatment group as shown by decreased tubulitis and tubular cell proliferation. Macrophage proliferation during acute allograft rejection is dependent on the interaction of M-CSF with its receptor c-fms. This pathway plays a significant and specific role in the accumulation of macrophages within a rejecting renal allograft.     

Tacrolimus versus cyclosporine induction therapy in pulmonary transplantation in miniature swine.

OBJECTIVE: Tacrolimus has been shown to provide superior immunosuppression in various solid organ transplant settings. The purpose of our study was to compare the survival of porcine lung allografts after induction with either cyclosporine A (CsA) or tacrolimus. METHODS: Single lung transplantation from MHC mismatched donors was performed in 10 minipigs. Immunosuppression included 1.5 mg/kg per day methylprednisolone and 1.0 mg/kg per day azathioprine. CsA (n=5) was adjusted to trough levels of 300-500 ng/ml, tacrolimus (n=5) was adjusted to 16-26 ng/ml. All immunosuppressive drugs were discontinued on postoperative day (POD) 28. Allograft survival was monitored by sequential chest radiographs, bronchoscopy and transbronchial biopsy histology. Peripheral blood leukocytes were scanned for donor chimerism and CD3, CD4, CD8 and CD25 expression. RESULTS: The animals survived a 4-week course of immunosuppression without radiological or histological signs of rejection on POD 28. Median allograft survival in CsA-treated animals was 55+/-15 days and all animals rejected their grafts within 42 days after withdrawal of immunosuppression. In tacrolimus-treated animals, median survival was 152+/-65 days with the longest survivor being electively sacrificed on POD 390 (P=0.0064). The degree of donor leukocyte chimerism and the frequency of CD4+CD25+ T-cells were higher in the tacrolimus group, however, these differences were not statistically significant. CONCLUSION: The results of our study show that primary immunosuppression with tacrolimus is superior to cyclosporine after pulmonary allotransplantation in a large animal model.     

Successful intestinal transplantation in pigs treated with cyclosporine

To date, it has not been possible to reliably prevent intestinal allograft rejection in large animals. This study was undertaken to determine if continuous i.v. cyclosporine (CsA) followed by p.o. CsA would prevent rejection in outbred piglets with orthotopic, in-continuity intestinal allografts. Untreated recipients (n = 7) died of rejection (2), interstitial pnuemontitis (3), or technical complications (2) at 5.3 +/- 1 days. Intestinal recipients treated with i.v. CsA 8 mg/kg/day and i.v. steroids (n = 3) died of rejection (mean survival 11.3 +/- 3.2 days). CsA 20 mg/kg/day i.v. plus i.v. steroids for 21 days, followed by p.o. CsA 25 mg/kg/day (n = 6) prevented rejection; however, most of the recipients developed fatal infections (mean survival 28 +/- 8 days). Intravenous CsA 15 mg/kg/day for 7-10 days (n = 16), followed by p.o. CsA 30 mg/kg/day in tapering doses reliably prevented graft rejection, permitting long-term survival (mean survival 121 +/- 32 days). Rejection did not occur in 7 animals when CsA was discontinued at 97 +/- 11 days. Seven animals surviving more than 100 days maintained normal nutritional indices and gained weight at the same rate as control animals. This study provides a rationale for further experimentation to determine the feasibility of intestinal transplantation in man.     

Site-specific immunosuppression using a new formulation of topical cyclosporine A with polyethylene glycol-8 glyceryl caprylate/caprate.

PURPOSE: Dermal application of immunosuppressants can be an effective means of achieving site-specific immunosuppression (SITE) on skin allografts in burn wound management and in the treatment of various immune skin disorders. We have previously reported success with topical cyclosporine A (tCsA) in the treatment of skin allograft rejection in rats. Using a new tCsA formulation with a penetration enhancer (PE), polyethylene glycol-8 (PEG-8) glyceryl caprylate/caprate (Labrasol, Gattefossé, St. Priest, France), in a trinary drug delivery system, we hypothesized that we would induce SITE and significantly delay rejection of dual skin allografts in rats. METHODS: Dual rat skin allografts from Lewis x Brown-Norway (LBN) donors were grafted to Lewis (Lew) recipients. Experimental animals (EXP, n = 7) received a 10-day course of systemic cyclosporine (sCsA, 8 mg/kg/day) followed by topical application. One of the two allografts on each experimental animal received tCsA/PE application (5 mg/kg/day) until sacrifice (tCsA/PE-treated). The other allograft received vehicle only (vehicle-treated). Allogeneic controls (ALLO-CON, n = 9) received no sCsA or tCsA. First signs of rejection were determined based on the initial observation of erythema, hair loss, flakiness, and/or scabs. RESULTS: The mean time to rejection for ALLO-CON allografts was 6.3 +/- 0.7 days (t test, P = 0.0013); for vehicle-treated allografts, 12.3 +/- 3.8 days (paired t test, P = 0.0146); and for tCsA/PE-treated allografts, 25.6 +/- 5.4 days. The disparity of days to rejection between dual allografts in the ALLO-CON group was 0.0 +/- 0.0 day and that between the tCsA/PE- and vehicle-treated dual allografts was 13.3 +/- 3.9 days (t test, P = 0.0016). CONCLUSIONS: A new formulation of tCsA in a trinary drug delivery system is successful at delaying the onset of rejection in dual skin allografts in rats by SITE, and PEG-8 glyceryl caprylate/caprate may represent a potentially effective transdermal penetration enhancer.     

Rapamycin, a potent immunosuppressive drug for vascularized heart, kidney, and small bowel transplantation in the rat

The effectiveness of rapamycin (RAPA) was examined for heart, kidney, and small bowel allografts in rats. Untreated or vehicle only-infused Wistar Furth (RT1u) recipients rejected Buffalo (RT1b) heart allografts within a mean survival time (MST) of 6.5 +/- 0.5 and 6.3 +/- 0.5 days, respectively. In contrast, a 14-day continuous intravenous (i.v.) infusion by an osmotic pump of 0.08 mg/kg/day RAPA to WFu recipients prolonged BUF heart allograft survival to an MST of 34.4 +/- 12.1 days (P = 0.0001). There was a graded dose-response to 0.16 mg/kg (39.0 +/- 8.7 days; P = 0.0001), 0.32 mg/kg (55.7 +/- 3.3 days; P = 0.0001) and 0.8 mg/kg (48.0 +/- 3.6; P = 0.0001). Furthermore, intraarterial/intragraft but not i.v. infusion of 0.02 mg/kg/day prolonged BUF heart allografts--namely, an MST of 14.6 +/- 1.4 days versus 8.6 +/- 2.6 days (P = 0.0001), respectively. Local delivery doses of RAPA were about as effective as the same dose delivered i.v.: 0.08 mg/kg MST 37.0 +/- 18.3 days (P = 0.0001); 0.32 mg/kg, 40.0 +/- 3.9 days (P = 0.0001); and 0.8 mg/kg, 54.8 +/- 8.2 days (P = 0.0001). Systemic i.v. RAPA therapy with 0.08 or 0.8 mg/kg/day prolonged the survival of BUF kidney grafts in WFu recipients--namely, an MST of 52.7 +/- 42.7 (NS) and 90.2 +/- 62.4 (P = 0.001) days, respectively, versus an MST of 11.6 +/- 1.5 days in control WFu recipients only infused with vehicle. While normal WFu rats reject heterotopic BUF small bowel allografts within an MST of 10.0 days, a 14-day course of i.v. RAPA treatment significantly (P = 0.0001) prolonged small bowel allograft survival to an MST of 26.8 +/- 3.7 days.     

Effect of a novel immunosuppressant, FTY720, on allograft survival after renal transplant in rats

FTY720 was developed by chemical modification of ISP-1 which was purified from culture filtrates of an ascomycete, Isaria sinclairii. We evaluated the effect of FTY720 on allograft survival using a rat renal transplantation model in which Wistar King Aptekman Hokkaido rats (WKAH, RT1(K)) served as the organ donor and Lewis rats (LEW, RT1(l)) as the recipient. WKAH renal allografts were acutely rejected by the untreated LEW recipients at a mean graft survival +/- SD of 7.2 +/- 0.4 days (n = 5). Consecutive oral administration of FTY720 following transplantation significantly prolonged allograft survival in a dose-dependent manner over the range of 0. 05-3 mg/kg/day. The mean allograft survival of the recipients treated with FTY720 at a doses of 0.05, 0.1, 0.5, 1, and 3 mg/kg/day was 12.2 +/- 3.3 (n = 5, p < 0.05, vs. untreated host), 11.2 +/- 2.4 (n = 5, p < 0.05, vs. untreated host), 13.6 +/- 0.9 (n = 5, p < 0.01, vs. untreated host), 14.6 +/- 1.7 (n = 5, p < 0.01, vs. untreated host) and 20.2 +/- 0.8 days (n = 5, p < 0.01, vs. untreated host). In the recipients treated with FTY720 (3 mg/kg/day), the number of peripheral blood lymphocytes significantly decreased. From the results of the flow cytometric study, FTY720 significantly diminished the percentage of interleukin-2 receptor (IL-2R)-positive cells in the allografts (6.34 +/- 0.81% in the untreated recipients vs. 3.10 +/- 0.86% in the recipients treated with FTY720, p < 0.05). As to the CD4/CD8 ratio of splenic cells and graft infiltrate, there was no significant difference between the untreated hosts and the recipients treated with FTY720. In conclusion, FTY720 significantly extended rat renal allograft survival and the immunosuppressive effects of FTY720 may be due to a reduction in not only the number of peripheral lymphocytes but also the percentage of IL-2R-positive cells in the allografts.     

The synergistic effect of low-dose cyclosporine and fluocinolone acetonide on the survival of rat allogeneic skin grafts

Both CsA and topical FA can prolong the survival of skin allografts under the proper conditions. This study was performed to determine if there is a synergistic effect between these two compounds. Buf (RT1b) rat split-thickness skin grafts were transplanted onto the backs of Lew (RT1l) rats. The MST for the control group was 9.89 +/- 0.35 days. In rats given oral CsA, 2.5 or 5 mg/kg, daily from the second day of grafting, the MST was 16.0 +/- 1.9 and 13.6 +/- 0.4 days (blood CsA levels were 166 +/- 20 and 640 +/- 32 ng/ml at the time of rejection, respectively. Topical FA applied daily beginning 72 hr after grafting resulted in a MST of 24.1 +/- 3.6 days. When both topical FA and 5 mg/kg oral CsA were used, the allograft survival time was more than 100 days in 4 of 7 animals. When oral CsA 2.5 mg/kg was combined with topical CsA and FA, the allograft rejection was delayed until 50 days postgrafting in four of six animals. The synergistic effects of oral CsA and topical FA is significant, and thus allows for the use of a subtherapeutic dosage of each compound and provides a potentially safe means for prolonging skin allograft survival.     

The effect of selective inhibition of cyclooxygenase (COX)-2 on acute cardiac allograft rejection

BACKGROUND: Using a rat (Lewis-Wistar Furth) abdominal heterotopic transplantation model, we reported previously that the expression of cyclooxygenase (COX)-2 is increased in parallel with that of nitric oxide synthase (NOS)-2 during cardiac allograft rejection. METHODS: To investigate effects of COX-2 inhibition in this model, allograft recipients were treated orally (PO) with 5 mg/kg per day of the tetra substituted furanone selective COX-2 inhibitor 5,5-dimethyl-3-(3 fluorophenyl)-4-(4 methylsulfonal) phenyl-2 (5H)-furanone (DFU) in 1% methyl cellulose solution. RESULTS: In the treated animals, allograft survival was increased from 6.3+/-0.5 to 12.6+/-2.6 days (P = .001). At days 3 and 5 posttransplantation, there were reductions in the extent of the inflammatory infiltrate, endovasculitis, myocardial edema, and cardiomyocyte damage in rejecting allografts. The mean numbers of apoptotic cardiomyocytes determined with the terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) technique were significantly reduced in DFU-treated grafts compared with untreated controls (P < 0.05). At day 3 posttransplantation, prostaglandin E2 synthesis by myocardial slices incubated with 100 microM bradykinin was reduced from 1,097+/-156 to 153+/-63 pg/mg of protein in the treated allografts (P < .005). At day 5, COX-2 protein and mRNA together with COX-2, NOS-2, and nitrotyrosine immunostaining in damaged cardiomyocytes were diminished in treated versus control grafts. CONCLUSION: The data indicate that the inhibition of COX-2 prolongs allograft survival and reduces myocardial damage and inflammation during acute cardiac allograft rejection.     

Peritransplant treatment with cobalt protoporphyrin attenuates chronic renal allograft rejection

Allogen-independent injury contributes to chronic rejection in renal allografts and heme oxygenase-1 (HO-1) has been shown to be protective in a number of settings. This study evaluated the effect of renal allograft recipient HO-1 up-regulation on chronic rejection in a rat model. Rat (F344 to Lewis) renal transplantation recipients were grouped: (i) cyclosporine (CsA) alone (0.75 mg/kg s.c. x 10 day; n = 5); (ii) CsA + low dose cobalt protoporphyrin (CoPP) an HO-1 inducer (0.5 mg/kg i.p. on days -5,0,5; n = 13) and (iii) CsA + high dose CoPP (5.0 mg/kg i.p. on days -5,0,5; n = 8). Renal function was assessed by serum creatinine levels on day 140. Histopathologic changes in allografts were graded. Morphometric analyses performed to objectively quantify the vascular changes and glomerulosclerosis. HO-1 expression quantified by Western blot and both HO-1 and endothelin (ET-1) localized using immunohistochemistry. Recipients treated with CsA + high dose CoPP had significantly decreased cortical scarring, vascular hyalinization and intimal thickness. They also had a significant, dose-dependent, reduction in luminal obliteration and glomerulosclerosis by morphometric analyses. This freedom from chronic rejection in recipients treated with CoPP translated into quiescent grafts at postoperative day 140 with immunostaining and Western blot demonstrating decreased level of HO-1 versus controls (P = 0.012). In summary, the peritransplant up-regulation of HO-1 in renal allograft recipients significantly attenuates chronic rejection in rat renal allografts by inhibiting transplant vasculopathy.     

Successful segmental intestinal transplantation in enterectomized pigs.

The aim of this study was to determine whether short-segment jejunal allografts maintained the viability and nutritional status of outbred recipient pigs treated with low-dose cyclosporine. The animals were subjected to total small bowel resection (from the ligament of Treitz to the ileocecal valve, approximately 15 m). Short-gut control animals (n = 8) who had no transplant died of malabsorption on day 62.5 +/- 4.1 (mean +/- SEM). Without cyclosporine immunosuppression, recipients (n = 5) of 3 m to 4 m jejunal allografts died of rejection on day 8.8 +/- 0.7. However enterectomized pigs (n = 11) who had segmental jejunal allograft transplants and were treated with cyclosporine (10 mg/kg/day) demonstrated significantly prolonged survival (to day 80.9 +/- 22.3; p less than 0.05). By 180 days after transplant, surviving animals increased their weight by almost 40%. In conclusion short-segment jejunal allografts significantly improved the mortality and morbidity rates from surgically created short bowel syndrome in pigs.     

Experimental and clinical experience with urine amylase monitoring for early diagnosis of rejection in pancreas transplantation

Pancreas allograft rejection in dogs with pancreaticocystostomy can be predicted in advance of hyperglycemia by monitoring the urinary amylase (UA) concentration (U/L): In initial experiments, UA values declined to less than 1000 1.3 +/- 0.2 days before hyperglycemia in nonimmunosuppressed dogs, 3.3 +/- 1.0 days in dogs treated with cyclosporine (CsA), and 9.3 +/- 0.7 days in dogs treated with CsA, azathioprine (Aza), and prednisone (triple therapy). Autotransplanted control dogs maintained high urine amylase concentrations indefinitely (mean 125,544 +/- 36,931). In a subsequent experiment, in 19 dogs with bladder-drained pancreas allografts on CsA only for prophylactic immunosuppression, a five-day course of antirejection treatment with Aza (5.0 mg/kg) and antilymphocyte globulin ALG (1 mg/kg) was started in group A (n = 10) when a raise in serum glucose was detected, and in group B (n = 9) when a drop of UA below 1000 was observed. The functional allograft survival rate was 9.2 +/- 0.5 days in group A (treatment started after hyperglycemia) and 29.0 +/- 5.7 days in group B (treatment started after drop in UA) (P = .002). The UA dropped in all dogs before hyperglycemia, at a mean of 2.7 days in group A and 20.8 days in group B. Clinically, 8 patients received a whole cadaver pancreas transplant with urinary drainage of the exocrine secretions. All were followed with UA monitoring. Three recipients lost the grafts for technical reasons. Three recipients lost the grafts for technical reasons. One had a primary non-function and UA was below 1000 U/24 hr; two developed abscesses and the grafts were removed while functioning with high UA values. Five grafts are currently functioning; 3 recipients had no rejection episodes and their UA values ranged from 30,000 to 100,000 U/24 hr during their entire postoperative course. The other two had rejection episodes. In both cases UA decreased to baseline levels 1 and 4 days in advance of the hyperglycemia. After antirejection treatment UA rose again to high values and plasma glucose levels declined. Both patients are currently insulin-independent, with UA values ranging from 10,000 to 200,000 U/24 hr. Both experimentally and clinically UA is an early predictor of pancreas allograft rejection. The institution of early treatment of rejection episodes in dogs, based on UA, significantly improved allograft survival. Urine amylase monitoring in pancreas transplant recipients could lead to an early treatment of rejection and improve graft survival.     

Immunosuppression by the JAK3 inhibitor CP-690,550 delays rejection and significantly prolongs kidney allograft survival in nonhuman primates

BACKGROUND: Janus kinase 3 (JAK3) mediates signal transduction from cytokine receptors using the common chain (gammac). Because mutations in genes encoding gammac or JAK3 result in immunodeficiency, we investigated the potential of a rationally designed inhibitor of JAK3, CP-690,550, to prevent renal allograft rejection in nonhuman primates. METHODS: Life-supporting kidney transplantations were performed between mixed leukocyte reaction-mismatched, ABO blood group-matched cynomolgus monkeys. Animals were treated with CP-690,550 (n = 18) or its vehicle (controls, n = 3) and were euthanized at day 90 or earlier if there was allograft rejection. RESULTS: Mean survival time (+/- standard error of mean) in animals treated with CP-690,550 (53 +/- 7 days) was significantly longer than in control animals (7 +/- 1 days, P=0.0003) and was positively correlated with exposure to the drug (r = 0.79, P < 0.01). Four treated animals were euthanized at 90 days with a normal renal function and low-grade rejection at final pathology. Occurrence of rejection was significantly delayed in treated animals (46 +/- 7 days from transplantation vs. 7 +/- 1 days in controls, P = 0.0003). Persistent anemia, polyoma virus-like nephritis (n = 2), and urinary calcium carbonate accretions (n = 3) were seen in animals with high exposure. Natural killer cell and CD4 and CD8 T-cell numbers were significantly reduced in treated animals. Blood glucose, serum lipid levels, and arterial blood pressure were within normal range in treated animals, and no cancers were demonstrated. CONCLUSIONS: CP-690,550 is the first reported JAK3 inhibitor combining efficacy and good tolerability in a preclinical model of allotransplantation in nonhuman primates and thus has interesting potential for immunosuppression in humans.     

Interferon-gamma knockout fails to confer protection against obliteration in heterotopic murine tracheal allografts.

BACKGROUND: Interferon-gamma, produced by T-helper cells, activates macrophages and increases expression of major histocompatibility complex (MHC) products in acute and chronic rejection. We investigated the role of interferon-gamma in murine heterotopic tracheal allografts. METHODS: Tracheas from BALB/c mice were heterotopically transplanted to BALB/c (12 isografts: 2 weeks [n = 6] and 4 weeks [n = 6], C57BL/6 (12 allografts: 2 weeks [n = 6] and 4 weeks [n = 6]) and C57BL/6 interferon-gamma knockout mice (12 interferon-gamma knockout allografts: 2 weeks [n = 4] and 4 weeks [n = 8]). BALB/c interferon-gamma knockout tracheas were transplanted to C57BL/6 mice (reverse knockout: 4 weeks [n = 6]) and BALB/c interferon-gamma knockout mice (4 weeks [n = 2]). C57BL/6 tracheas were transplanted to Bm12 mice (MHC Class II mismatch allografts: 4 weeks [n = 6]). Conventional histology and immunohistochemistry for CD4, CD8 and CD11b were performed. RESULTS: Minimal (<20%) obliteration was seen at 2 weeks in the allograft groups. No obliteration was seen in the isograft groups. However, all allografts were completely obliterated at 4 weeks. Interferon-gamma knockout allograft combinations displayed severe rejection characterized by intense intra- and extraluminal infiltration by CD4-, CD8- and CD11b-labeled cells. The MHC Class II mismatch allograft group showed normal epithelium and mild sub-epithelial infiltration by CD4+ cells at 4 weeks (CD8-, CD11b-). CONCLUSIONS: Absence of interferon-gamma does not protect the allograft from obliteration. Epithelial destruction by cytotoxic T cells appears to be an important mechanism in the development of obliteration in murine heterotopic tracheal allografts.     

Monotherapy with LF 15-0195, an analogue of 15-deoxyspergualin,significantly prolongs renal allograft survival in monkeys

BACKGROUND: LF 15-0195 is a novel, more potent, and less toxic analogue of 15-deoxyspergualin, an antibiotic used as an immunosuppressive agent to prevent rejection of organ transplants. This study was undertaken to determine whether LF 15-0195 monotherapy would prevent renal allograft rejection in a nonhuman primate model. METHODS: In the study groups, recipients received LF 15-0195 monotherapy at doses of 0.065 mg/kg per day (group 2, n=4), 0.13 mg/kg per day (group 3, n=4), or 0.2 mg/kg per day (group 4, n=4), administered subcutaneously, on postoperative days 0 to 14. RESULTS: Group 1 consisted of untreated control recipients, all of which developed advanced graft rejection after surviving for an average of 6.5+/-0.6 days. LF 15-0195 treatment significantly prolonged graft survival in groups 2, 3, and 4, to 20+/-20 days, 49+/-5 days, and 39+/-4 days, respectively. Animals in groups 3 and 4 demonstrated no evidence of rejection during LF 15-0195 treatments. The animals maintained stable renal function for 2 weeks after LF 15-0195 withdrawal but gradually developed rejection at 5 to 6 weeks. Pathologic studies demonstrated that vascular graft rejection was attenuated in LF 15-0195-treated allografts, compared with control specimens. These groups also demonstrated transient reductions in lymphocyte counts during treatment, which returned to normal levels 2 weeks after LF 15-0195 withdrawal. Total serum concentrations of IgM and IgG decreased by a mean of 20.4% and a mean of 31.4%, respectively, at the end of LF 15-0195 treatment (postoperative day 14). LF 15-0195 did not significantly alter thrombocyte counts or hemoglobin levels. Necropsy studies showed no evidence of drug toxicity in the heart, liver, spleen, intestines, stomach, or colon. CONCLUSIONS: LF 15-0195 monotherapy significantly prolonged renal allograft survival in monkeys. These encouraging data suggest that this novel agent may be of future value in clinical transplantation.     

Prolongation of survival of fully allogeneic cardiac grafts and generation of regulatory cells by a histamine receptor 2 antagonist

BACKGROUND: The effects of histamine on immunologic responses via the histamine receptor 2 (HR2) have been studied, but few investigations explored the immunomodulatory role of histamine in vivo. We examined whether the HR2 antagonist ranitidine affects the alloimmune response in a murine model of cardiac transplantation. METHODS: CBA (H-2k) recipients were given no treatment or one intravenous injection of ranitidine on the day of transplantation of a heart from C57BL/10 (H-2b) donors. Survival of the allografts was recorded. The effect of the ranitidine treatment on cell proliferation and cytokine production was assessed by mixed leukocyte culture and enzyme-linked immunosorbent assays. An adoptive transfer study was conducted to determine whether regulatory cells were generated. The effect on graft survival of adding FK506 to the ranitidine treatment was also examined. RESULTS: CBA recipients given ranitidine (60 mg/kg) had prolonged graft survival (median survival time [MST], 87 days). Ranitidine treatment also suppressed the proliferation of splenocytes and production of interleukin (IL)-2 and up-regulated IL-10 production. Adoptive transfer of splenocytes and CD4 cells from ranitidine-treated allograft recipients induced significant prolongation of allograft survival in naive secondary recipients (MST, 71 and >100 days, respectively). CBA recipients given both ranitidine and FK506 (0.1 mg/kg/day for 14 days) had indefinite survival of cardiac allografts (MST, >100 days). CBA recipients treated with FK506 alone rejected the allografts (MST, 27 days). CONCLUSION: In our model, ranitidine treatment induced significantly prolonged survival of fully allogeneic cardiac grafts, generated CD4 regulatory cells, and indefinite survival when combined with FK506 (0.1 mg/kg/day).