Impact of GAD65 and IA2 autoantibodies on islet allograft survival.

Introduction: Islet transplantation (ITx) shows promise in treating T1D, but the role of islet autoantibodies on graft survival has not been clearly elucidated. We aimed to analyze the effect of GAD65 and IA2 autoantibody status on graft survival and attainment of insulin independence in subjects with T1D who underwent ITx. Method: We conducted a retrospective cohort study on 47 ITx recipients from 2000 to 2018. Islet infusion was performed via intrahepatic portal (n=44) or onto the omentum via laparoscopic approach (n=3). Immunosuppression involved anti-IL2 receptor antibody, anti-TNF, and dual combinations of sirolimus, tacrolimus, or mycophenolate mofetil (Edmonton-like) in 38 subjects (80.9%). T-cell depletion induction with Edmonton-like maintenance was used in 9 subjects (19%). GAD65 and IA2 autoantibodies were assessed pre-transplant and post-transplant (monthly) until graft failure, and categorized as persistently negative, persistently positive, or seroconverters. Graft survival was analyzed using U-Mann-Whitney test, and Quade's nonparametric ANCOVA adjusted for confounders. Kaplan-Meier and Log-Rank tests were employed to analyze attainment of insulin independence. P value <0.05 indicated statistical significance. Results: ITx recipients with persistent autoantibody negativity (n = 21) showed longer graft function (98 [61 - 182] months) than those with persistent autoantibody positivity (n = 18; 38 [13 - 163] months), even after adjusting for immunosuppressive induction protocol (P = 0.027). Seroconverters (n=8) had a median graft survival time of 73 (7.7 - 167) months, which did not significantly differ from the other 2 groups. Subjects with persistently single antibody positivity to GAD65 (n = 8) had shorter graft survival compared to negative islet autoantibody (GAD65/IA2) subjects (n = 21; P = 0.016). Time of graft survival did not differ in subjects with single antibody positivity to IA2. The proportion of insulin independence attainment was similar irrespective of autoantibody status. Conclusion: The persistence of islet autoantibodies, as markers of islet autoimmunity, may represent an underappreciated contributing factor to the failure of transplanted ß cells. Whether induction with T-cell depletion may lead to improved graft survival, independent of islet autoantibody status, could not be evaluated in our cohort. Larger prospective studies are needed to further address the role of islet autoantibody status on islet graft survival.

HLA-B Matching Prolongs Allograft Survival in Islet Cell Transplantation.

Islet cell transplantation (ITx) is an effective therapeutic approach for selected patients with type 1 diabetes with hypoglycemia unawareness and severe hypoglycemia events. In organ transplantation, human leukocyte antigen (HLA) mismatching between donor and recipient negatively impacts transplant outcomes. We aimed to determine whether HLA matching has an impact on islet allograft survival. Forty-eight patients were followed up after islet transplantation at our institution from 2000 to 2020 in a retrospective cohort. Patients underwent intrahepatic ITx or laparoscopic omental approach. Immunosuppression was dependent upon the protocol. We analyzed HLA data restricted to A, B, and DR loci on allograft survival using survival and subsequent multivariable analyses. Patients were aged 42.8 ± 8.4 years, and 64.3% were female. Diabetes duration was 28.6 ± 11.6 years. Patients matching all three HLA loci presented longer graft survival (P = 0.030). Patients with ≥1 HLA-B matching had longer graft survival compared with zero matching (P = 0.025). The number of HLA-B matching was positively associated with time of graft survival (Spearman's rho = 0.590; P = 0.034). Analyses adjusted for confounders showed that ≥1 matching for HLA-B decreased the risk of allograft failure (P = 0.009). Our data suggest that HLA-B matching between recipients and donors improved islet allograft survival. Matching all three HLA loci (A, B, and DR) was also associated with prolonged islet allograft survival. Prospective studies and a larger sample size are warranted to validate our findings.

Prolonged Islet Allograft Function is Associated With Female Sex in Patients After Islet Transplantation.

BACKGROUND: Islet transplantation (ITx) has proved to be effective in preventing severe hypoglycemia and improving metabolic control in selected subjects with type 1 diabetes. Long-term graft function remains a challenge. Estrogens have been shown to protect ß cells from metabolic stresses and improve revascularization of transplanted human islets in the mouse. We aimed to evaluate the influence of sex in allograft survival of ITx recipients. METHODS: We analyzed a retrospective cohort of ITx recipients (n = 56) followed-up for up to 20 years. Allograft failure was defined as a stimulated C-peptide <0.3 ng/mL during a mixed-meal tolerance test. Subjects were divided into recipients of at least 1 female donor (group 1) and recipients of male donors only (group 2). RESULTS: Group 1 subjects (n = 25) were aged 41.5 ± 8.4 years and group 2 subjects (n = 22) 45.9 ± 7.3 years (P = 0.062). Female recipient frequency was 44.8% (n = 13) in group 1 and 55.2% (n = 16) in group 2 (P = 0.145). Group 2 developed graft failure earlier than group 1 (680 [286-1624] vs 1906 [756-3256] days, P = 0.038). We performed additional analyses on female recipients only from each group (group 1, n = 16; group 2, n = 20). Female recipients in group 1 exhibited prolonged allograft function compared with group 2, after adjustment for confounders (odds ratio, 28.6; 95% CI, 1.3-619.1; P < 0.05). CONCLUSION: Recipients of islets from at least 1 female donor exhibited prolonged graft survival compared with recipients of islets from exclusively male donors. In addition, female recipients exhibited prolonged survival compared with male recipients following ITx of at least 1 female donor.

Umbilical cord mesenchymal stem cells for COVID-19 acute respiratory distress syndrome: A double-blind, phase 1/2a, randomized controlled trial.

Acute respiratory distress syndrome (ARDS) in COVID-19 is associated with high mortality. Mesenchymal stem cells are known to exert immunomodulatory and anti-inflammatory effects and could yield beneficial effects in COVID-19 ARDS. The objective of this study was to determine safety and explore efficacy of umbilical cord mesenchymal stem cell (UC-MSC) infusions in subjects with COVID-19 ARDS. A double-blind, phase 1/2a, randomized, controlled trial was performed. Randomization and stratification by ARDS severity was used to foster balance among groups. All subjects were analyzed under intention to treat design. Twenty-four subjects were randomized 1:1 to either UC-MSC treatment (n = 12) or the control group (n = 12). Subjects in the UC-MSC treatment group received two intravenous infusions (at day 0 and 3) of 100 ± 20 × 106 UC-MSCs; controls received two infusions of vehicle solution. Both groups received best standard of care. Primary endpoint was safety (adverse events [AEs]) within 6 hours; cardiac arrest or death within 24 hours postinfusion). Secondary endpoints included patient survival at 31 days after the first infusion and time to recovery. No difference was observed between groups in infusion-associated AEs. No serious adverse events (SAEs) were observed related to UC-MSC infusions. UC-MSC infusions in COVID-19 ARDS were found to be safe. Inflammatory cytokines were significantly decreased in UC-MSC-treated subjects at day 6. Treatment was associated with significantly improved patient survival (91% vs 42%, P = .015), SAE-free survival (P = .008), and time to recovery (P = .03). UC-MSC infusions are safe and could be beneficial in treating subjects with COVID-19 ARDS.

Epicardial adipose tissue has a unique transcriptome modified in severe coronary artery disease.

OBJECTIVE: To explore the transcriptome of epicardial adipose tissue (EAT) as compared to subcutaneous adipose tissue (SAT) and its modifications in a small number of patients with coronary artery disease (CAD) versus valvulopathy. METHODS: SAT and EAT samples were obtained during elective cardiothoracic surgeries. The transcriptome of EAT was evaluated, as compared to SAT, using an unbiased, whole-genome approach in subjects with CAD (n = 6) and without CAD (n = 5), where the patients without CAD had cardiac valvulopathy. RESULTS: Relative to SAT, EAT is a highly inflammatory tissue enriched with genes involved in endothelial function, coagulation, immune signaling, potassium transport, and apoptosis. EAT is lacking in expression of genes involved in protein metabolism, tranforming growth factor-beta (TGF-beta) signaling, and oxidative stress. Although underpowered, in subjects with severe CAD, there is an expression trend suggesting widespread downregulation of EAT encompassing a diverse group of gene sets related to intracellular trafficking, proliferation/transcription regulation, protein catabolism, innate immunity/lectin pathway, and ER stress. CONCLUSIONS: The EAT transcriptome is unique when compared to SAT. In the setting of CAD versus valvulopathy, there is possible alteration of the EAT transcriptome with gene suppression. This pilot study explores the transcriptome of EAT in CAD and valvulopathy, providing new insight into its physiologic and pathophysiologic roles.

Dexamethasone reduces energy expenditure and increases susceptibility to diet-induced obesity in mice.

OBJECTIVE: To investigate how long-term treatment with dexamethasone affects energy expenditure and adiposity in mice and whether this is influenced by feeding on a high-fat diet (HFD). DESIGN AND METHODS: Mice were placed on a HFD for 2 weeks and started on dexamethasone at 5 mg/kg every other day during the next 7 weeks. RESULTS: Treatment with dexamethasone increased body fat, an effect that was more pronounced in the animals kept on HFD; dexamethasone treatment also worsened liver steatosis caused by the HFD. At the same time, treatment with dexamethasone lowered the respiratory quotient in chow-fed animals and slowed nightly metabolic rate in the animals kept on HFD. In addition, the acute VO2 acceleration in response to ß3 adrenergic-stimulation was significantly limited in the dexamethasone-treated animals, as a result of marked decrease in UCP-1 mRNA observed in the brown adipose tissue of these animals. CONCLUSIONS: Long-term treatment with dexamethasone in a mouse model of diet-induced obesity decreases brown adipose tissue thermogenesis and exaggerates adiposity and liver steatosis. © 2013 American Institute of Chemical Engineers AIChE J, 2013.

Nutritional status and behavior in subjects with type 1 diabetes, before and after islet transplantation.

BACKGROUND: To investigate whether changes of nutritional status and behavior are associated with islet transplantation (ITx) and to assess their possible mechanisms. METHODS: In this observational study, 52 subjects with type 1 diabetes, 30 of whom received ITx, underwent nutritional assessments. The study consisted of questionnaires complemented by a dietary intake recording, anthropometric measurements, and body composition analysis. Laboratory tests were also reviewed as part of the follow up. RESULTS: After ITx, significant reductions in body weight (3.7 kg; P<0.0001), body mass index (1.39 kg/m2; P<0.0001), waist circumference (3.96 cm; P=0.006), and fat weight (3.28 kg; P<0.01) were observed. The average consumption of carbohydrate and protein were also lower than pretransplant, together with some micronutrients (vitamins B12 and B6, zinc, and phosphorus). Insulin administration and changes in A1C were not associated with a significant change in anthropometric measurements. Subjects on exenatide after ITx showed significantly lower weight and body mass index than those not taking exenatide. CONCLUSIONS: ITx is associated with modifications in nutritional behavior and status. Drugs and health conditions are likely to be at least in part responsible for these changes, but a voluntary modification of eating habits by the patients also plays a role. Strict monitoring of nutritional parameters, counseling by experts in nutrition, and multivitamin/mineral supplement after ITx could be of benefit to the patients.

Improved metabolic control and quality of life in seven patients with type 1 diabetes following islet after kidney transplantation.

BACKGROUND: The beneficial effects of glycemic control on both survival and function of transplanted kidneys in patients with type 1 diabetes mellitus (T1DM) and end-stage renal disease (ESRD) have been recognized. METHODS: Herein, we present the clinical outcome of a single-center pilot trial of islet after kidney (IAK) transplantation in seven patients with T1DM. The immunosuppression protocol for the kidney graft was converted to sirolimus+tacrolimus regimen 6 months before islet transplantation to exclude negative effects on kidney graft function. Primary endpoint was achievement of insulin independence after transplantation. Clinical outcome, metabolic control, severe hypoglycemia, kidney function, Quality of Life (QOL) psychometric measures, and adverse events were monitored. RESULTS: Seven patients showed graft function with improved metabolic control (A1c, fasting glycemia, and metabolic tests) after IAK (14,779+/-3,800 IEQ/kg). One-year insulin independence was 30% with persistent graft function in 86% (C-peptide-positive). A1c reduction was 1.95+/-0.31% from baseline (P<0.0001). No episodes of severe hypoglycemia were observed, even after resuming insulin. The direct consequence of these benefits was a significant improvement in diabetes QOL. Adverse events included procedure-related pleural effusion (n=2), cholecystitis (n=1), and additional immunosuppression-related, all resolved without sequelae. Kidney function (by estimated glomerular filtration rate) remained stable during follow-up in six of seven patients. CONCLUSIONS: Islet transplantation represents a feasible therapeutic option for patients with T1DM bearing a stable kidney allograft. Insulin independence at 1 year is lower than what reported in islet transplant alone. Nevertheless, clear benefits in terms of optimal metabolic control and absence of severe hypoglycemia are invariably present.

Resolution of severe atopic dermatitis after tacrolimus withdrawal.

Tacrolimus is an immunosuppressive agent used in solid organ and islet transplantation. Its topical form has shown benefit in the treatment of inflammatory skin conditions. Although tacrolimus has a wide spectrum of side effects, dermatological complications related to systemic tacrolimus therapy are limited in the literature. Atopic dermatitis (AD) is a chronic pruritic cutaneous condition that usually begins in infancy and is characterized by an increased Th2 response. We report the case of a patient with type 1 diabetes mellitus (T1DM) and history of AD latent for 10 years who developed severe dermatitis and alopecia 5 months after undergoing allogeneic islet transplantation and initiating a steroid-free immunosuppressive regimen with sirolimus and tacrolimus maintenance. After exclusion of other possible causes for the progression and exacerbation of the clinical presentation of AD, discontinuation of tacrolimus and introduction of mycophenolate mofetil resulted in full remission of the symptoms. The beneficial effects of tacrolimus withdrawal suggest a cause-effect relationship between this adverse event and the utilization of the drug. Islet graft function remained stable after modification of the therapeutic regimen (stable glycemic control and unchanged C-peptide).

The use of the BD oxygen biosensor system to assess isolated human islets of langerhans: oxygen consumption as a potential measure of islet potency.

The measurement of cellular oxygen consumption rate (OCR) is a potential tool for the assessment of metabolic potency of isolated islets of Langerhans prior to clinical transplantation. We used a commercially available 96-well plate fluoroprobe, the BD Oxygen Biosensor System (OBS), to estimate OCR in 27 human islet preparations, and compared these results to those of concurrent mouse transplantations. OCR was estimated both from the dO2 at steady state and from the transient rate of change of dO2 during the initial culture period immediately after seeding ("dO2 slope"). To demonstrate the validity of the OBS-derived values, it was shown that they scaled linearly with islet equivalent number/DNA concentration and with each other. These measurements were obtained for each preparation of islets incubated in media supplemented with either low (2.2 mM) or high (22 mM) glucose. Concurrently, one to three athymic nude mice were transplanted with 2,000 IEQs under the kidney capsule. The OCR Index, defined as the ratio of the DNA-normalized "dO2 slope" in high glucose to that in low glucose, proved highly predictive of mouse transplant results. Of the 69 mice transplanted, those receiving islets where the OCR Index exceeded 1.27 were 90% likely to reverse within 3 days, whereas those receiving islets with an OCR Index below 1.27 took significantly longer, often failing to reverse at all over a 35-day time period. These results suggest that the OBS could be a useful tool for the pretransplant assessment of islet cell potency.

Immunosuppression and procedure-related complications in 26 patients with type 1 diabetes mellitus receiving allogeneic islet cell transplantation.

BACKGROUND: The success of sirolimus and low-dose tacrolimus in islet cell transplantation has influenced many transplant centers to utilize this novel regimen. The long-term safety and tolerability of this steroid-free immunosuppressive protocol for allogeneic islet transplantation has yet to be determined. METHODS: We transplanted 26 adult patients with long standing type 1 diabetes mellitus between April 2000 and June 2004. Immunosuppression consisted of induction with daclizumab and maintenance therapy with tacrolimus and sirolimus. Adverse events (AEs) in patients were followed and graded using the Common Terminology Criteria for Adverse Events, version 3.0 (National Cancer Institute). RESULTS: To date, the majority of patients were able to remain on the immunosuppression combination for up to 22+/-11 months. Four patients were successfully converted to Mycophenolate Mofetil due to tacrolimus-related toxicity. Withdrawal from immunosuppression was decided in four patients due to hypereosinophilic syndrome, parvovirus infection, aspiration pneumonia, and severe depression, respectively. Six patients required filgrastim therapy for neutropenia. Transient elevation of liver enzymes was observed in most patients early after islet infusion. Increased LDL in 20 patients required medical treatment. CONCLUSION: There was a varying range of AEs, most of them mild and self-limiting; however, some required urgent medical attention. The majority of patients were able to tolerate and remain on this effective regimen. To date, no deaths, cytomegalovirus disease, graft-versus-host disease, or posttransplant lymphoproliferative disease has been observed.

Islet transplantation in type 1 diabetes mellitus using cultured islets and steroid-free immunosuppression: Miami experience.

Following the success obtained with transplantation of fresh human islets under steroid-free immunosuppression, this trial evaluated the transplantation of islets that had undergone a period of in vitro culture and the potential of tumor necrosis factor (TNF-alpha) blockade to improve islet engraftment. Subjects included 16 patients with type 1 diabetes mellitus (T1DM); half were randomly assigned to receive Infliximab immediately preceding initial infusion. Immunosuppression consisted of daclizumab induction and sirolimus/tacrolimus maintenance. Out of 16 subjects 14 achieved insulin independence with one or two islet infusions; adverse events precluded completion in two. Without supplemental infusions, 11/14 (79%) subjects were insulin independent at 1 year, 6/14 (43%) at 18 months; these same subjects remain insulin independent at 33+/-6 months. While on immunosuppression, all patients maintained graft function. Out of 14 patients, 8 suffered chronic partial graft loss, likely immunological in nature, 5 of these received supplemental infusions. Currently, 11 subjects remain on immunosuppression, 8 (73%) are insulin independent, two with supplemental infusions. Insulin independent subjects demonstrated normalization of HbA1c, fructosamine and Mean Amplitude of Glycemic Excursions (MAGE) values. No clinical benefit of infliximab was identified. These results demonstrate that transplantation of cultured human islet allografts results in reproducible insulin independence in all subjects under this immunosuppressive regimen, comparable to that of freshly transplanted islets (Edmonton protocol).

Prolonged allogeneic islet graft survival by protoporphyrins.

Transplantation of islets of Langerhans in patients with type 1 diabetes allows for improved metabolic control and insulin independence. The need for chronic immunosuppression limits this procedure to selected patients with brittle diabetes. Definition of therapeutic strategies allowing permanent engraftment without the need for chronic immunosuppression could overcome such limitations. We tested the effect of the use of protoporphyrins (CoPP and FePP), powerful inducers of the cytoprotective protein heme-oxygenase 1 (HO-1), on allogeneic islet graft survival. Chemically induced diabetic C57BL/6 mice received DBA/2 islets. Treatment consisted in peritransplant administration of CoPP or saline. Islets were either cultured in the presence of FePP or vehicle before implant. Short-course administration of CoPP led to long-term islet allograft survival in a sizable proportion of recipients. Long-term graft-bearing animals rejected third-party islets while accepting a second set donor-specific graft permanently, without additional treatment. Preconditioning of islets with FePP by itself led to improved graft survival in untreated recipients, and provided additional advantage in CoPP-treated recipients, resulting in an increased proportion of long-term surviving grafts. Preconditioning of the graft with protoporphyrins prior to implant resulted in reduction of class II expression. Administration of protoporphyrins to the recipients of allogeneic islets also resulted in transient powerful immunosuppression with reduced lymphocyte proliferative responses, increased proportion of regulatory cells (CD4+CD25+), decreased mononuclear cell infiltrating the graft, paralleled by a systemic upregulation of HO-1 expression. All these mechanisms may have contributed to the induction of donor-specific hyporesponsiveness in a proportion of the protoporphyrin-treated animals.

Prolonged Allogeneic Islet Graft Survival by Protoporphyrins.

Transplantation of islets of Langerhans in patients with type 1 diabetes allows for improved metabolic control and insulin independence. The need for chronic immunosuppression limits this procedure to selected patients with brittle diabetes. Definition of therapeutic strategies allowing permanent engraftment without the need for chronic immunosuppression could overcome such limitations. We tested the effect of the use of protoporphyrins (CoPP and FePP), powerful inducers of the cytoprotective protein hemeoxygenase 1 (HO-1), on allogeneic islet graft survival. Chemically induced diabetic C57BL/6 mice received DBA/2 islets. Treatment consisted in peritransplant administration of CoPP or saline. Islets were either cultured in the presence of FePP or vehicle before implant. Short-course administration of CoPP led to long-term islet allograft survival in a sizable proportion of recipients. Long-term graft-bearing animals rejected third-party islets while accepting a second set donor-specific graft permanently, without additional treatment. Preconditioning of islets with FePP by itself led to improved graft survival in untreated recipients, and provided additional advantage in CoPP-treated recipients, resulting in an increased proportion of long-term surviving grafts. Preconditioning of the graft with protoporphyrins prior to implant resulted in reduction of class II expression. Administration of protoporphyrins to the recipients of allogeneic islets also resulted in transient powerful immunosuppression with reduced lymphocyte proliferative responses, increased proportion of regulatory cells (CD4+CD25+), decreased mononuclear cell infiltrating the graft, paralleled by a systemic upregulation of HO-1 expression. All these mechanisms may have contributed to the induction of donor-specific hyporesponsiveness in a proportion of the protoporphyrintreated animals.

Alterations of the female reproductive system in recipients of islet grafts.

BACKGROUND: Transplantation of allogeneic tissues is becoming a wider practice for the replacement of organ function lost to congenital or acquired pathologies. Chronic immunosuppression remains a necessity to prevent organ rejection, despite increased risks of infection, organ toxicity, and malignancies. Abnormalities of female gonadal function in patients of reproductive age are recognized, however, pathological alterations of the reproductive system in patients treated with new generation immunosuppressive drugs are still poorly documented. METHODS: We report herein our observations of abnormalities of the reproductive system in 13 female recipients of allogeneic islets for type 1 diabetes, under immunosuppression therapy based on daclizumab induction and tacrolimus/sirolimus maintenance. RESULTS: Menstrual cycle alterations and clinically significant ovarian cysts were frequently observed in our patients, some requiring medical or surgical intervention. All ovarian cysts appeared of benign nature. CONCLUSIONS: Our findings suggest that pre- and posttransplant evaluation of female patients should include menstrual history, baseline pelvic ultrasound, and hormonal levels to assess the presence and monitor the progression of such alterations.

Cytomegalovirus prevalence and transmission after islet allograft transplant in patients with type 1 diabetes mellitus.

Cytomegalovirus (CMV) serological status of transplant donors and recipients has important implications on antiviral prophylaxis, morbidity/mortality, donor selection and hospital stay. We evaluated CMV prevalence in our islet transplant candidates (ITC) in comparison with organ donors. We correlated the CMV serological status of our ITC with serology for Epstein-Barr virus and Parvovirus B19, auto-antibodies, patient's age, age at DM onset, duration of DM, gender, race, ABO group, HLA haplotype and C-peptide levels. Cytomegalovirus transmission after islet transplant using the Edmonton regimen was also evaluated. Cytomegalovirus seropositivity varied according to patient group, age, gender and race. Type 1 DM patients had reduced odds of CMV seropositivity when compared with organ donors. In all groups studied, older patients, females, and non-Caucasians were more likely to be CMV seropositive. In addition, no CMV reactivation, infection or disease was observed among our transplanted patients using this steroid-free regimen even after donor/recipient CMV mismatch.

The effect of simultaneous CD154 and LFA-1 blockade on the survival of allogeneic islet grafts in nonobese diabetic mice.

BACKGROUND: The rate of success in clinical transplantation of islets of Langerhans has dramatically improved with perspectives of wide-scale applicability for patients with type 1 diabetes. One drawback is the need for lifelong immunosuppression, which is associated with significant side effects. Immunomodulatory strategies devoid of side effects and with tolerogenic potential, such as co-stimulatory blockade, would be a great improvement if successful. In this study, the authors have explored the effect of simultaneous blockade of CD40/CD154 and intercellular adhesion molecule (ICAM)/lymphocyte function-associated antigen (LFA)-1 interactions. METHODS: Spontaneously diabetic nonobese diabetic (NOD) mice underwent transplantation with allogeneic (C57BL/6) islets and were treated with anti-CD154 monoclonal antibody (mAb) (500 microg, three doses), anti-LFA-1 mAb (100 microg, three doses), or a combination of both in the early peritransplant period. In another set of experiments, LFA-1 engagement was impaired by transplanting islets isolated from ICAM-1-knockout (KO) mice. RESULTS: Untreated animals rejected their grafts within 10 days. LFA-1 blockade alone did not result in improved islet graft survival, whereas CD154 blockade alone increased graft survival to 18 days. Simultaneous blockade of both pathways led to significantly improved islet graft survival to 30 days (ICAM-1-KO islets plus anti-CD154), 35 days (anti-LFA-1 plus anti-CD154), and 44 days (ICAM-1-KO islets plus anti-LFA-1 plus anti-CD154). CONCLUSIONS: These data suggest that a synergistic effect for prolonged graft survival can be obtained by simultaneously targeting CD154 and LFA-1 in the challenging model of islet allotransplantation in NOD mice. The observation of similar results with anti-LFA-1 mAb and with ICAM-1-KO grafts suggests a key role of direct antigen presentation for the activation of LFA-1-driven signaling.

Long-term islet allograft survival in nonobese diabetic mice treated with tacrolimus, rapamycin, and anti-interleukin-2 antibody.

BACKGROUND: Nonobese diabetic (NOD) mice develop autoimmune diabetes with features similar to those observed in the human disease. The concurrence of allorecognition and recurrence of autoimmunity might explain why most of the treatments successful in preventing islet allograft destruction in other nonautoimmune combinations often fail in NOD recipients. To assess the value of the NOD mouse model for the evaluation of treatments relevant to clinical islet transplantation, the authors have tested the effect of a protocol closely resembling the one successfully used in the Edmonton clinical trial on the survival of islet allografts in NOD mice. METHODS: C57BL/6 islets were transplanted under the kidney capsule of spontaneously diabetic NOD mice. Treatment consisted of a combination of rapamycin, tacrolimus, and anti-interleukin (IL)-2 monoclonal antibody. Control groups received each treatment alone, a combination of two agents, or no treatment. RESULTS: Untreated animals invariably lost their graft within 13 days. Administration of rapamycin and tacrolimus significantly prolonged graft survival, with two of seven animals bearing a functional graft longer than 100 days. Addition of anti-IL-2 antibody therapy further improved graft survival, with six of eight grafts functioning longer than 100 days and two of eight grafts functioning longer than 200 days. CONCLUSIONS: In view of the limited success obtained with other treatments in this model, the dramatic prolongation of graft survival observed in the authors' study, by using a therapy that mimics one successfully used in clinical trials, seems to validate the NOD mouse as a meaningful model for the study of therapeutic interventions for the prevention of islet graft loss.