Effect of Immigration Status on Outcomes in Pediatric Kidney Transplant Recipients

Kidney transplantation is the optimal treatment for children with end-stage renal disease. For children with undocumented immigration status, access to kidney transplantation is limited, and data on transplant outcomes in this population are scarce. The goal of the present retrospective single-center study was to compare outcomes after kidney transplantation in undocumented children with those of US citizen children. Undocumented residency status was identified in 48 (17%) of 289 children who received a kidney transplant between 1998 and 2010. In undocumented recipients, graft survival at 1 and 5 years posttransplantation was similar, and mean estimated glomerular filtration rate at 1 year was higher than that in recipients who were citizens. The risk of allograft failure was lower in undocumented recipients relative to that in citizens at 5 years posttransplantation, after adjustment for patient age, donor age, donor type, and HLA mismatch (p < 0.04). In contrast, nearly one in five undocumented recipients who reached 21 years of age lost their graft, primarily because they were unable to pay for immunosuppressive medications once their state-funded insurance had ended. These findings support the ongoing need for immigration policies for the undocumented that facilitate access to work-permits and employment-related insurance for this disadvantaged group.

Under Utilization of Pancreas Transplants in Cystic Fibrosis Recipients in the United Network Organ Sharing (UNOS) Data 1987-2014

Despite a high prevalence of pancreatic endocrine and exocrine insufficiency in cystic fibrosis (CF), pancreas transplantation is rarely reported. United Network for Organ Sharing (UNOS) data were used to examine utilization of pancreas transplant and posttransplant outcomes in CF patients. Between 1987-2014, CF patients (N = 4600) underwent 17 liver-pancreas, three lung-pancreas, one liver-lung pancreas, four kidney-pancreas, and three pancreas-only transplants. Of the 303 CF patients who received liver transplantation, 20% had CF-related diabetes (CFRD) before transplantation, and nine of those received a liver-pancreas transplant. Of 4241 CF patients who underwent lung transplantation, 33% had CFRD before transplantation, and three of those received a pancreas transplant. Of 49 CF patients who received a liver-lung transplant, 57% had CFRD before transplantation and one received a pancreas transplant. Posttransplantation diabetes developed in 7% of CF pancreas transplant recipients versus 24% of CF liver and 29% of CF lung recipients. UNOS has no data on pancreas exocrine insufficiency. Two-year posttransplantation survival was 88% after liver-pancreas transplant, 33% after lung-pancreas transplant, and 100% after pancreas-kidney and pancreas-only transplants. Diabetes is common pretransplantation and posttransplantation in CF solid organ transplant recipients, but pancreas transplantation remains rare. Further consideration of pancreas transplant in CF patients undergoing other solid organ transplant may be warranted.

A Comparative Analysis of the Safety, Efficacy, and Cost of Islet Versus Pancreas Transplantation in Nonuremic Patients With Type 1 Diabetes

Few current studies compare the outcomes of islet transplantation alone (ITA) and pancreas transplantation alone (PTA) for type 1 diabetes (T1D). We examined these two beta cell replacement therapies in nonuremic patients with T1D with respect to safety, graft function and cost. Sequential patients received PTA (n = 15) or ITA (n = 10) at our institution. Assessments of graft function included duration of insulin independence; glycemic control, as measured by hemoglobin A1c; and elimination of severe hypoglycemia. Cost analysis included all normalized costs associated with transplantation and inpatient management. ITA patients received one (n = 6) or two (n = 4) islet transplants. Mean duration of insulin independence in this group was 35 mo; 90% were independent at 1 year, and 70% were independent at 3 years. Mean duration of insulin independence in PTA was 55 mo; 93% were insulin independent at 1 year, and 64% were independent at 3 years. Glycemic control was comparable in all patients with functioning grafts, as were overall costs ($138 872 for ITA, $134 748 for PTA). We conclude that with advances in islet isolation and posttransplant management, ITA can produce outcomes similar to PTA and represents a clinically viable option to achieve long-term insulin independence in selected patients with T1D.

Changes in vertebral bone marrow fat and bone mass after gastric bypass surgery: A pilot study

Bone marrow fat may serve a metabolic role distinct from other fat depots, and it may be altered by metabolic conditions including diabetes. Caloric restriction paradoxically increases marrow fat in mice, and women with anorexia nervosa have high marrow fat. The longitudinal effect of weight loss on marrow fat in humans is unknown. We hypothesized that marrow fat increases after Roux-en-Y gastric bypass (RYGB) surgery, as total body fat decreases. In a pilot study of 11 morbidly obese women (6 diabetic, 5 nondiabetic), we measured vertebral marrow fat content (percentage fat fraction) before and 6 months after RYGB using magnetic resonance spectroscopy. Total body fat mass declined in all participants (mean ± SD decline 19.1 ± 6.1 kg or 36.5% ± 10.9%, p<0.001). Areal bone mineral density (BMD) decreased by 5.2% ± 3.5% and 4.1% ± 2.6% at the femoral neck and total hip, respectively, and volumetric BMD decreased at the spine by 7.4% ± 2.8% (p<0.001 for all). Effects of RYGB on marrow fat differed by diabetes status (adjusted p=0.04). There was little mean change in marrow fat in nondiabetic women (mean +0.9%, 95% CI -10.0 to +11.7%, p=0.84). In contrast, marrow fat decreased in diabetic women (-7.5%, 95% CI -15.2 to +0.1%, p=0.05). Changes in total body fat mass and marrow fat were inversely correlated among nondiabetic (r=-0.96, p=0.01) but not diabetic (r=0.52, p=0.29) participants. In conclusion, among those without diabetes, marrow fat is maintained on average after RYGB, despite dramatic declines in overall fat mass. Among those with diabetes, RYGB may reduce marrow fat. Thus, future studies of marrow fat should take diabetes status into account. Marrow fat may have unique metabolic behavior compared with other fat depots.

Routine upper GI series after gastric bypass does not reliably identify anastomotic leaks or predict stricture formation

BACKGROUND

Many surgeons who perform Roux-en-Y gastric bypass (RYGB) for morbid obesity routinely obtain an upper gastrointestinal (GI) series in the early postoperative period to search for anastomotic leaks and signs of stricture formation at the gastrojejunostomy. We hypothesized that this practice is unreliable.

METHODS

We analyzed 654 consecutive RYGBs, of which 63% were completed laparoscopically. An upper GI series was obtained in 634 (97%) patients. The radiographic findings (leak or delayed emptying) were compared with clinical outcomes (leak or stricture formation) to calculate the sensitivity and specificity. Univariate analysis identified risk factors for leaks or stricture formation; events were too few for multivariate analysis.

RESULTS

Of 634 routine upper GI series, anastomotic leaks at the gastrojejunostomy were diagnosed in 5 (0.8%); 2 of these 5 were later reinterpreted as artifacts. Four leaks were not seen on the initial upper GI series, yielding an overall sensitivity of 43% and a positive predictive value (PPV) of 60%. Univariate analysis showed that cases done early (odds ratio [OR] 5.4 for the first 100 cases, p = 0.02) and prolonged operating time (OR 7.8 for cases >or= 300 min, p = 0.01) were associated with leaks. Emptying into the Roux-en-Y limb was delayed in 127 (20%) of the upper GI series. Strictures requiring dilatation developed in 16 (2.4%) patients. The PPV of delayed emptying for stricture formation was 6%. Risk factors for stricture formation included stapled anastomosis (OR 7.8, p = 0.002), surgeon inexperience (OR 2.9 for first 50 cases, p = 0.04), and delayed emptying (OR 3.3; p = 0.02).

CONCLUSIONS

Because the incidence of anastomotic complications and the sensitivity of upper GI series were both low, routine upper GI series did not reliably identify leaks or predict stricture formation. A selective approach, whereby imaging is reserved for patients with clinical evidence of a leak or stricture, may be more appropriate.

Antibody-mediated rejection of a pancreas allograft

The role of antibody-mediated rejection (AMR) in pancreas transplantation is poorly understood. Here, we report on a patient who developed AMR of his pancreas allograft after receiving a simultaneous pancreas-kidney transplant. Pre-operative enhanced cytotoxicity and flow cytometry T-cell crossmatches were negative; B-cell crossmatches were not performed as per institutional protocol. The patient's post-operative course was significant for elevated serum amylase levels and development of hyperglycemia approximately 1 month after transplantation. A pancreatic biopsy at this time showed no cellular infiltrate but strong immunofluorescent staining for C4d in the interacinar capillaries. Analysis of the patient's serum identified donor-specific HLA-DR alloantibodies. He received intravenous immunoglobulin (IVIg), rituximab and plasmapheresis, and his pancreatic function normalized. We conclude that clinically significant AMR can develop in a pancreas allograft and recommend that pancreatic biopsies be assessed for C4d deposition if the patient has risk factors for AMR and/or the pathologic evidence for cell-mediated rejection is underwhelming.

The failure of intrathymic transplantation of nonimmunogenic islet allografts to promote induction of donor-specific unresponsiveness

Freshly isolated allogenic pancreatic islets transplanted into the thymus of transiently immunosuppressed rats are not rejected but survive indefinitely while also inducing a state of specific unresponsiveness that permits survival of secondary donor-strain islets transplanted extrathymically. Since freshly isolated pancreatic islets contain intraislet antigen-presenting cells as well as endocrine cells it is unclear which cellular component is primarily responsible for mediating unresponsiveness. We therefore examined the impact of pretransplant in vitro culture (a maneuver which selectively depletes intraislet APCs) on the capacity of islet allografts to induce unresponsiveness after intrathymic implantation. APC-depleted pancreatic islets, which are known to have reduced immunogenicity, survived indefinitely in the thymus of allogeneic hosts whether or not brief immunosuppression was employed, but failed to promote survival of subsequent donor-strain islets transplanted to an extrathymic site. These findings emphasize the central role of APCs in the induction of transplantation tolerance in this model, and are consistent with the established role of this population in the development of T cell tolerance in the thymus.

Examination of the mechanisms responsible for tolerance induction after intrathymic inoculation of allogeneic bone marrow

OBJECTIVE

This study examined the immunologic mechanism(s) responsible for the induction of transplantation tolerance in rats pretreated with intrathymic inoculation of donor strain bone marrow.

SUMMARY BACKGROUND DATA

Induction of unresponsiveness may involve deletion and/or inactivation of donor-reactive T-cell precursors maturing in a thymus harboring donor alloantigen or generation of regulatory/suppressor cells. It was reasoned that, if unresponsiveness is caused by deletion of alloreactive clones, the presence of additional thymic tissue devoid of donor alloantigen permits normal maturation of T-cells and, thus, prevents induction of tolerance. However, if unresponsiveness were primarily mediated by regulatory/suppressor cells, the presence of noninoculated thymic tissue should not affect the induction of tolerance.

METHODS

Three strategies were used to define the cellular basis of cardiac and islet allograft survival in WF recipients of intrathymic LEW donor bone marrow as follows: (1) inoculation of bone marrow either into the native thymus and/or into an ectopic thymus, (2) limiting dilution analyses of the frequency of precursor cytotoxic T-lymphocytes (CTLp), and (3) adoptive transfer to syngeneic secondary hosts.

RESULTS

Inoculation of bone marrow into only one lobe of the native thymus and/or into an ectopic thymus did not promote consistent survival of subsequent LEW cardiac allografts. Tolerant hosts displayed significant reductions in CTLp frequencies against donor alloantigens. Adoptive transfer of spleen cells from tolerant WF hosts harboring long-standing cardiac allografts led to permanent survival of LEW cardiac allografts in all secondary recipients. However, transfer of spleen cells from WF animals that received intrathymic LEW bone marrow (but no cardiac allograft) did not promote survival of LEW cardiac allografts in naive secondary hosts.

CONCLUSIONS

These results indicate that the unresponsive state after intrathymic inoculation of bone marrow cells is primarily mediated by deletion and/or inactivation of donor-specific T-cell precursors maturing in a chimeric thymus. The demonstration by adoptive transfer studies of putative regulatory/suppressor cells suggested an important role for the persistence of donor alloantigen (supplied by a vascularized allograft) in the maintenance of the unresponsive state.

Promotion of rat cardiac allograft survival by intrathymic inoculation of donor splenocytes

Donor-specific unresponsiveness to LEW heterotopic cardiac allografts was induced in WF rats following intrathymic inoculation of LEW splenocytes in conjunction with a single intraperitoneal dose of antilymphocyte serum. In contrast, LEW cardiac allografts were promptly rejected in WF recipients pretreated with an intravenous inoculation of donor splenocytes. Without transient immunosuppression with antilymphocyte serum neither intrathymic nor intravenous inoculation of splenocytes led to allograft survival. Substitution of antilymphocyte serum by a short course of cyclosporine did not permit allograft survival, suggesting that a T-cell-depleting regimen is crucial to tolerance induction by this protocol. The unresponsive state could be transferred to secondary syngeneic hosts by spleen cells from long-term recipients of intrathymic splenocytes and cardiac allografts but not by spleen cells from recipients of intrathymic splenocytes alone. This suggests that persistence of donor alloantigen from the graft is necessary for maintenance of the tolerant state. The unresponsive state after intrathymic inoculation of allogeneic splenocytes may be mediated through interaction of maturing host thymocytes with donor alloantigen.

Prolonged survival of rat orthotopic liver allografts after intrathymic inoculation of donor-strain cells

Permanent donor-specific tolerance to tissue or organ allografts can be readily achieved without immunosuppression by administration of donor lymphohematopoietic cells to neonatal rodents. In adult recipients, however, induction of transplantation tolerance by this strategy generally requires intensive cytoablative conditioning of the recipient. We have now demonstrated that intrathymic inoculation of donor bone marrow or hepatic cells in conjunction with a single dose of antilymphocyte serum is effective in prolonging survival of DA rat orthotopic liver allografts in LEW strain recipients, which ordinarily rapidly reject such transplants. The unresponsive state achieved is donor-specific, as evidenced by the failure of intrathymic inocula of third-party WF cells to promote survival of LEW recipients of orthotopic DA liver allografts. Moreover, intravenous administration of the donor cells fails to extend liver allograft survival, demonstrating that the inoculum must be present in the thymus to promote unresponsiveness. Established DA liver allografts induced a state of systemic tolerance in LEW hosts, allowing their subsequent acceptance of donor-strain skin allografts. We hypothesize that the unresponsive state achieved by intrathymic inoculation of donor cells may result from the deletion or functional inactivation of alloreactive clones in a thymus bearing donor alloantigens. In this regard, cells of the macrophage/dendritic lineage (descendants of the bone marrow inoculum or hepatic Kupffer cells) may play a critical role by promoting thymic microchimerism and exerting modulatory effect on T cell development.

Induction of donor-specific tolerance to rat cardiac allografts by intrathymic inoculation of bone marrow

BACKGROUND

Induction of donor-specific tolerance to tissue or organ allografts can readily be achieved by administration of allogeneic bone marrow to neonatal rodents; however, in adult recipients induction of transplantation tolerance by this strategy generally requires intensive cytoablative conditioning. Described here is a novel method of promoting transplantation tolerance that involves inoculation of donor bone marrow into the thymus of transiently immunosuppressed adult recipients.

METHODS

Prospective Wistar-Furth recipients were inoculated with allogeneic Lewis bone marrow cells (BMCs) either intrathymically or intravenously in conjunction with a single dose of antilymphocyte serum 2 to 3 weeks before receiving donor-strain cardiac allografts. Recipients were monitored for graft survival and examined for presence of hematopoietic chimerism.

RESULTS

Intrathymic but not intravenous inoculation of donor BMCs led to permanent survival of donor-strain cardiac allografts, whereas third-party Dark agouti cardiac allografts were rejected promptly. Persistence of donor chimerism was demonstrated in the thymus of Wistar-Furth recipients of intrathymic Lewis BMCs for as long as 3 weeks after BMC inoculation.

CONCLUSIONS

Intrathymic inoculation of BMCs concurrently with a single dose of antilymphocyte serum induces donor-specific unresponsiveness to rat cardiac allografts. The unresponsiveness may be the result of deletion or functional inactivation of alloreactive clones maturing in a thymus bearing donor alloantigen. Intrathymic inoculation of BMCs deserves further evaluation as a possible clinical strategy for the induction of transplantation tolerance.

Promotion of pancreatic islet allograft survival by intrathymic transplantation of bone marrow

An important goal in the treatment of insulin-dependent diabetes by pancreatic islet transplantation is the development of strategies that allow permanent survival of islet allografts without continuous host immunosuppression. In this study, we demonstrate that inoculation of allogeneic bone marrow into the thymus of adult rats treated with a single dose of anti-lymphocyte serum induces an unresponsive state that permits survival of subsequent pancreatic islet allografts transplanted to an extrathymic site. This effect is donor specific, cannot be reproduced by systemic administration of bone marrow, and is associated with persistence of chimeric cells in the thymus of the recipient. In addition, lymph node cells from long-term recipients of intrathymic bone marrow display markedly reduced proliferative responses to donor alloantigens in mixed lymphocyte culture. Interaction of maturing thymocytes with foreign alloantigens may produce the unresponsiveness. This model offers a potential approach for establishing donor-specific allograft acceptance in adult recipients.

Prevention of autoimmune diabetes in the BB rat by intrathymic islet transplantation at birth

Spontaneous diabetes in the BioBreeding (BB) rat, like human type I diabetes, results from the destruction of pancreatic islets by autoreactive T lymphocytes recognizing beta cell-specific antigens. T cell tolerance is in part mediated by interactions of maturing thymocytes with antigens expressed in the thymic microenvironment; islets were therefore implanted into the thymus of neonatal diabetes-prone BB rats to determine whether exposure of T cell precursors to beta cell antigens could influence the development of diabetes. This treatment completely prevented diabetes and insulitis in the native pancreas. The effect may be the result of specific modulation of diabetogenic T cells maturing in an islet-bearing thymus.

Intrathymic islet transplantation in the spontaneously diabetic BB rat

Recently it was demonstrated that pancreatic islet allografts transplanted to the thymus of rats made diabetic chemically are not rejected and induce specific unresponsiveness to subsequent extrathymic transplants. The authors report that the thymus can also serve as an effective islet transplantation site in spontaneously diabetic BB rats, in which autoimmunity and rejection can destroy islets. Intrathymic Lewis islet grafts consistently reversed hyperglycemia for more than 120 days in these rats, and in three of four recipients the grafts promoted subsequent survival of intraportal islets. In contrast intraportal islet allografts in naive BB hosts all failed rapidly. The authors also show that the immunologically privileged status of the thymus cannot prevent rejection of islet allografts in Wistar Furth (WF) rats sensitized with donor strain skin and that suppressor cells are not likely to contribute to the unresponsive state because adoptive transfer of spleen cells from WF rats bearing established intrathymic Lewis islets fails to prolong islet allograft survival in secondary hosts.

Major-histocompatibility-complex restricted and nonrestricted autoimmune effector mechanisms in BB rats

To investigate whether the immunologic mechanisms of autoimmune pancreatic beta-cell destruction are MHC restricted, we examined the relative vulnerability of islet allografts from a panel of MHC-compatible and -incompatible donors to autoimmune damage after transplantation to spontaneously diabetic BB recipients. To circumvent a potentially confounding allograft response to the foreign islet graft, we utilized two strategies: (1) pretransplant in vitro culture of islets to delete intraislet APCs; and (2) induction of islet donor-specific immunologic tolerance in diabetes-prone BB rats. Experiments employing organ culture to prevent rejection demonstrated that MHC-incompatible grafts were significantly less vulnerable to autoimmunity than MHC-compatible grafts. In contrast, when we used the model of immunologic tolerance to exclude rejection, both MHC-compatible and -incompatible islet grafts were equally susceptible to autoimmune damage. The reason for this discrepancy has not been defined fully but may be related to our observation that tolerant BB animals exhibit increased peripheral blood NK-cell activity. NK cells are known to be cytotoxic to islets in vitro and could play a role in a non-MHC-restricted diabetogenic response in vivo. We conclude that both MHC-restricted and nonrestricted mechanisms are capable of contributing to anti-beta-cell autoimmunity in BB rats.

Induction of donor-specific unresponsiveness by intrathymic islet transplantation

The application of isolated pancreatic islet transplantation for treatment of diabetes mellitus has been hampered by the vulnerability of islet allografts to immunologic rejection. Rat islet allografts that were transplanted into the thymus of recipients treated with a single injection of anti-lymphocyte serum survived indefinitely. A state of donor-specific unresponsiveness was achieved that permitted survival of a second donor strain islet allograft transplanted to an extrathymic site. Maturation of T cell precursors in a thymic microenvironment that is harboring foreign alloantigen may induce the selective unresponsiveness. This model provides an approach for pancreatic islet transplantation and a potential strategy for specific modification of the peripheral immune repertoire.

The effect of islet cell culture in vitro at 24 degrees C on graft survival and MHC antigen expression

A period of in vitro culture prior to transplantation has been shown to prolong the survival of many types of MHC-incompatible endocrine grafts. The effectiveness of this strategy has been attributed to a selective depletion of intragraft antigen-presenting cells. We report that in vitro culture at 24 degrees C results in a significantly better survival of rat isolated islet allografts than does culture at 37 degrees C. Using in vitro assays of APC activity, we were unable to detect differences in the quantity of residual intraislet APCs between 24 degrees C and 37 degrees C culture preparations. In contrast, islet endocrine cells cultured at 24 degrees C evidenced a reduced level of cell surface class I MHC antigen expression and were significantly less vulnerable to lysis in vitro by CTL. These findings suggest that culture at 24 degrees C produces islet alterations other than APC depletion, and that its beneficial effect on graft survival correlates with a reduction in endocrine cell class I MHC antigen expression.

Suppression of carbon monoxide excretion rate by tin protoporphyrin

The effect of a single prophylactic dose of tin protoporphyrin on the carbon monoxide (CO) excretion rate of antibiotic-treated neonatal rats before and after hematoma formation was evaluated. The CO excretion rate, reflecting the rate of bilirubin production, of tin protoporphyrin-treated (TP-H) rats 24 hours after injection of 65 mole of tin protoporphyrin per kilogram (time [t] = 0 hours) was approximately 18% lower than those of the saline-control (S-C) and saline-hematoma (S-H) rats, but this difference was no longer evident at t = 43 hours. After hematoma formation at t = 44 hours, the CO excretion rate of the S-H rats increased rapidly; this increase was delayed and lessened in the TP-H rats. At eight hours posthematoma (t = 52 hours), the CO excretion rate of the TP-H rats was significantly lower than that of the S-H rats, 53 +/- 2 vs 73 +/- 3 microL/kg/hr, respectively. A maximal rate of 89 +/- 5 microL/kg/hr was reached 25 hours posthematoma in the S-H rats (t = 69 hours), as compared with 80 +/- 3 microL/kg/hr at 44 hours posthematoma in the TP-H rats (t = 88 hours). The recovery of injected blood as CO over a 68-hour study period was approximately 90% for the S-H rats and approximately 65% for the TP-H rats. At t = 112 hours, hepatic heme oxygenase activity of the TP-H rats was still significantly lower than that of the S-H and S-C rats; however, plasma bilirubin concentrations of all three groups were similar. These studies demonstrate that tin protoporphyrin is an effective in vivo inhibitor of endogenous heme catabolism as measured by the CO excretion rate in antibiotic-treated neonatal rats with and without artificially created hematomas.

Effect of tin protoporphyrin on the excretion rate of carbon monoxide in newborn rats after hematoma formation

This study evaluated the efficacy of tin protoporphyrin (TP), a competitive inhibitor of heme oxygenase, in suppressing the total body excretion rate of carbon monoxide (CO), an index of total bilirubin formation, in neonatal rats with artificially created hematomas. Wistar rat litters less than 12 h old were each divided into three groups of similar weight and treated as follows: (a) saline control (S); (b) hematoma, 80 microliter blood (H); (c) TP, 65 mumol/kg, and hematoma (TP-H). CO excretion of the H group increased rapidly after hematoma formation, reaching a maximum value of 79 +/- 4 SE microliter/kg/h 25 h later. Treatment with TP did not affect the pattern of CO excretion or its magnitude (78 +/- 2 SE microliter/kg/h, 25 h posthematoma). The S group showed no increase in CO excretion at this time (40 +/- 2 SE microliter/kg/h). At the conclusion of the experiment (45 h posthematoma), the plasma total bilirubin levels were slightly lower in the TP-H rats (1.0 +/- 0.1 SE mg/dl) than in H rats (1.2 +/- 0.1 SE mg/dl). The S rats had a plasma total bilirubin concentration of 0.8 +/- 0.1 SE mg/dl. The hepatic and splenic heme oxygenase activities were decreased by 61% (p less than 0.001) and 48% (p less than 0.05), respectively, in the TP-H rats as compared to the H rats. The S and H rats had similar enzyme activities. The results of this study suggest that though single-dose TP decreased tissue heme oxygenase activity, it did not significantly affect total bilirubin formation.