The Role of a "Technology Navigator" in an Academic Diabetes Clinic: A Feasibility Evaluation

Patient-generated device data play an important role in diabetes management. However, acquiring these data remains a challenge. This project aimed to understand whether implementing dedicated "Technology Navigator" (TN) personnel at a large academic diabetes clinic could facilitate access to device data without increasing work for clinic staff. A sample of visits pre- and post-TN implementation (n = 173) showed a 22% (41% vs. 19%) increase in patients who successfully shared their data from home before their visit and a 52% (67% vs. 15%) increase in visits where data were available to the provider for review before the appointment, whereas billing claims for continuous glucose monitor interpretation increased by 86% during the same period. Time analysis suggests that home uploads could save up to 747 h in medical assistant labor annually. Incorporating a TN may improve data availability, decrease time spent on nonbillable activities, and support data interpretation and billing.

PSUN39 A rare presentation of autoimmune thyroid diseases and myasthenia gravis: A clinical case report

 

We report a case of a 37-years-old female that presented with a three-week history of diplopia, ptosis, muscle weakness, difficulty chewing, tachycardia, and fatigue; these clinical symptoms were concerning for acute myasthenia gravis crisis. The diagnosis of Myasthenia gravis was further confirmed by a positive immunology workup. Chest CT imaging during her assessment showed anterior mediastinal mass/enlarged thymus indicative of thymic hyperplasia. Medical therapy with intravenous immune globulin, pyridostigmine and further treatment with high-dose steroid. She had a positive response to treatment but still reported persistent symptoms of fatigue, tachycardia, and intermittent diplopia, raising suspicions for underlying Graves’ thyrotoxicosis. Thyroid function testing was performed which showed a very suppressed thyroid-stimulating hormone (TSH) and elevated Free t4 levels. Further workup for Graves thyroid autoimmune antibodies indicative of extremely elevated thyroid stimulating hormone receptor autoantibodies consistent with Graves’ disease. We initiated medical therapy for Graves’ disease with a beta-blocker and thioamide (methimazole). She endorsed progressive improvement in her symptoms following treatment for Grave's disease. She was discharged with high dose steroids, pyridostigmine, and appropriate therapy for Graves’ disease. She did well after her discharge from the hospital and six months afterwards she returned to the hospital for a robot-assisted right thymectomy. Final pathology report indicative of non-thymomatous myasthenia gravis. She continued to follow up with us in the endocrinology outpatient clinic. Her steroid therapy was tapered off and medical therapy for Graves’ disease was continued accordingly. She demonstrated a positive response to medical therapy with remarkable improvement in the remaining of her symptoms, especially her neurological and ocular symptoms after initiation of treatment for Graves’ disease.

Conclusion

we report two rare concomitant autoimmune diseases, myasthenia gravis, and Graves’ disease. Both conditions have similar overlapping clinical features making diagnosis and treatment challenging in clinical practice. It is well reported in clinical literature and studies that hyperthyroidism may worsen symptoms of MG and management of hyperthyroidism in the setting of MG may lead to worsening of myasthenia symptoms; hence, certain precautions should be taken to avoid worsening symptoms of myasthenia gravis. Therefore, we call for more case-control, case series and clinical trials to explore more clinical knowledge about the association between the two conditions and formulate better management strategies.

Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

A Multicenter Randomized Trial Evaluating the Insulin-Only Configuration of the Bionic Pancreas in Adults with Type 1 Diabetes

Objective: To evaluate the insulin-only configuration of the iLet® bionic pancreas (BP) using insulin aspart or insulin lispro in adults with type 1 diabetes (T1D). Methods: In this multicenter, randomized, controlled trial, 161 adults with T1D (18-79 years old, baseline HbA1c 5.5%-13.1%, 32% using multiple daily injections, 27% using a pump without automation, 5% using a pump with predictive low glucose suspend, and 36% using a hybrid closed loop system before the study) were randomly assigned 2:1 to use the BP (N = 107) with insulin aspart or insulin lispro (BP group) or a standard-of-care (SC) control group (N = 54) using their usual insulin delivery plus continuous glucose monitoring (CGM). The primary outcome was HbA1c at 13 weeks. Results: Mean HbA1c decreased from 7.6% ± 1.2% at baseline to 7.1% ± 0.6% at 13 weeks with BP versus 7.6% ± 1.2% to 7.5% ± 0.9% with SC (adjusted difference = -0.5%, 95% confidence interval -0.6% to -0.3%, P < 0.001). Over 13 weeks, mean time in range 70-180 mg/dL (TIR) increased by 11% (2.6 h/d) and mean CGM glucose was reduced by 16 mg/dL with BP compared with SC (P < 0.001). Improvement in these metrics was seen during the first day of BP use and by the end of the first week reached levels that remained relatively stable through 13 weeks. Analyses of time >180 mg/dL, time >250 mg/dL, and standard deviation of CGM glucose all favored the BP group (P < 0.001). The CGM-measured hypoglycemia was low at baseline (median time <54 mg/dL of 0.21% [3 min/d] for the BP group and 0.11% [1.6 min/d] for the SC group) and not significantly different between groups over the 13 weeks (P = 0.51 for time <70 mg/dL and 0.33 for time <54 mg/dL). There were 7 (6.5% of 107 participants) severe hypoglycemic events in the BP group and 2 events in the SC group (1.9% of 54 participants, P = 0.40). Conclusions: In adults with T1D, use of the BP with insulin aspart or insulin lispro improved HbA1c, TIR, and hyperglycemic metrics without increasing CGM-measured hypoglycemia compared with standard of care. Clinical Trial Registry: clinicaltrials.gov; NCT04200313.

Multicenter, Randomized Trial of a Bionic Pancreas in Type 1 Diabetes

BACKGROUND

Currently available semiautomated insulin-delivery systems require individualized insulin regimens for the initialization of therapy and meal doses based on carbohydrate counting for routine operation. In contrast, the bionic pancreas is initialized only on the basis of body weight, makes all dose decisions and delivers insulin autonomously, and uses meal announcements without carbohydrate counting.

METHODS

In this 13-week, multicenter, randomized trial, we randomly assigned in a 2:1 ratio persons at least 6 years of age with type 1 diabetes either to receive bionic pancreas treatment with insulin aspart or insulin lispro or to receive standard care (defined as any insulin-delivery method with unblinded, real-time continuous glucose monitoring). The primary outcome was the glycated hemoglobin level at 13 weeks. The key secondary outcome was the percentage of time that the glucose level as assessed by continuous glucose monitoring was below 54 mg per deciliter; the prespecified noninferiority limit for this outcome was 1 percentage point. Safety was also assessed.

RESULTS

A total of 219 participants 6 to 79 years of age were assigned to the bionic-pancreas group, and 107 to the standard-care group. The glycated hemoglobin level decreased from 7.9% to 7.3% in the bionic-pancreas group and did not change (was at 7.7% at both time points) in the standard-care group (mean adjusted difference at 13 weeks, -0.5 percentage points; 95% confidence interval [CI], -0.6 to -0.3; P<0.001). The percentage of time that the glucose level as assessed by continuous glucose monitoring was below 54 mg per deciliter did not differ significantly between the two groups (13-week adjusted difference, 0.0 percentage points; 95% CI, -0.1 to 0.04; P<0.001 for noninferiority). The rate of severe hypoglycemia was 17.7 events per 100 participant-years in the bionic-pancreas group and 10.8 events per 100 participant-years in the standard-care group (P = 0.39). No episodes of diabetic ketoacidosis occurred in either group.

CONCLUSIONS

In this 13-week, randomized trial involving adults and children with type 1 diabetes, use of a bionic pancreas was associated with a greater reduction than standard care in the glycated hemoglobin level. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; ClinicalTrials.gov number, NCT04200313.).

Associations of plasma miRNAs with waist circumference and insulin resistance among women with polycystic ovary syndrome - Pilot study

BACKGROUND

Insulin resistance (IR) and central obesity are common in polycystic ovary syndrome (PCOS), but pathomechanisms for IR in PCOS are not established. Circulating microRNAs (miRNAs) are non-invasive biomarkers of epigenetic regulation that may contribute to the pathogenesis of IR and central adiposity in PCOS.

METHODS

We conducted a pilot study to examine associations of circulating miRNAs with IR and central adiposity among women with PCOS (n = 11) using high-throughput miRNA sequencing. We fit generalized linear models examining associations of waist circumference and HOMA-IR with plasma miRNAs. We used false discovery rate (FDR)-adjusted cutoff p < 0.1 to correct for multiple testing. We used miRDB's Gene Ontology (GO) tool to identify predicted pathways for top hits.

RESULTS

Mean age and BMI of participants were 27.9 years and 32.5 kg/m2, respectively. Lower levels of miR-1294 were associated with higher waist circumference (β = -0.10, FDR = 0.095). While no miRNAs were associated with HOMA-IR at our FDR cut off <0.1, 11 miRNAs were associated with waist circumference and 14 miRNAs with HOMA-IR at unadjusted p < 0.01, including members of the highly conserved miR-17/92 cluster and miR-1294 (β = -0.10, p < 0.001). The GO analysis of miR-1294 identified 54 overrepresented pathways, including "negative regulation of insulin receptor signaling" (FDR = 0.019), and 6 underrepresented pathways.

CONCLUSIONS

Plasma miR-1294 along with members of the miR-17/92 cluster and miRNAs involved in insulin signaling may be associated with central obesity and insulin resistance in PCOS. Larger studies among women with and without PCOS are needed to validate these findings.

Prevalence of SGLT2i and GLP1RA use among US adults with type 2 diabetes

AIMS

To determine national prevalence of sodium-glucose contransporter-2 inhibitor (SGLT2i) and glucagon-like peptide-1 receptor agonist (GLP1RA) use among adults with type 2 diabetes mellitus (T2DM).

METHODS

We studied adults with T2DM and eGFR ≥ 30 mL/min/1.73 m² who participated in the cross-sectional National Health and Nutrition Examination Survey (NHANES), focusing on the 2017-2020 examination cycle, a key time period prior to widespread dissemination of pivotal trial results and corresponding clinical practice guidelines. We tested prevalence of SGLT2i and GLP1RA use among subgroups based on demographic variables and relevant comorbidities, including chronic kidney disease (CKD), congestive heart failure (CHF), and atherosclerotic cardiovascular disease (ASCVD). We compared use of SGLT2i and GLP1RA to other glucose-lowering medications and assessed trends from prior NHANES cycles.

RESULTS

Among 1375 participants studied in 2017-2020, mean age was 60 years, 46% were women, 13% self-identified as non-Hispanic Black, 10% self-identified as Mexican American, 37% had CKD, 8.5% had CHF, and 23% had ASCVD. The prevalence of SGLT2i and GLP1RA use was 5.8% and 4.4%, respectively. Among adults with CKD, CHF, or ASCVD, SGLT2i were used by 7.7% and GLP1RA were used by 3.5%. Differences in SGLT2i or GLP1RA use were observed by age, race, ethnicity, health insurance status, body mass index, and by whether a single healthcare provider was identified as responsible for diabetes management. Biguanides, sulfonylureas, DPP-4 inhibitors, and insulin were used more frequently than SGLT2i or GLP1RA. Prevalence of SGLT2i but not GLP1RA use increased significantly from 2013-2014 to 2017-2020.

CONCLUSIONS

SGLT2i and GLP1RA use is low among adults with T2DM, including among those with strong indications. Enhanced implementation of these agents is crucial to improving kidney and cardiovascular outcomes and mitigating health disparities in T2DM.

An unusual manifestation of olfactory neuroblastoma

A 62-year-old woman presented with an 11-month history of worsening nasal symptoms of rhinorrhoea, anosmia, nasal congestion and intermittent epistaxis. MRI revealed a large mass in the upper nasal vault. Biopsy of the mass revealed an olfactory neuroblastoma. While waiting resection, she acutely developed severe proximal muscle weakness, lethargy and lower extremity oedema. Blood glucose was elevated, and hypokalaemic metabolic alkalosis was noted. Elevated serum cortisol level of 95.7 µg/dL (8.7-22.4 µg/dL) and markedly elevated 24-hour urinary cortisol level of 6962.3 µg/24 hours (4.0-50.0 µg/24 hours) with concurrent adrenocorticotropic hormone (ACTH) level of 171 pg/mL (6-58 pg/mL) were suggestive of an ACTH-dependent source of hypercortisolism. A subsequent positive high-dose dexamethasone suppression test was consistent with ectopic ACTH production. She underwent near-total resection of the right nasal mass followed by radiotherapy, resulting in complete resolution of signs and symptoms of cortisol excess.

Polycystic ovarian syndrome

Women with PCOS present with signs of chronic anovulation, hyperandrogenism, and metabolic abnormalities. The NIH recently embraced the Rotterdam criteria to broadly identify all the phenotypes of PCOS. Women with PCOS are often obese with insulin resistance and hence have an increased susceptibility to glucose intolerance and type 2 diabetes. Future research should focus on the genetic, epigenetic, and environmental determinants of PCOS to develop new therapies to address the prevention of this disorder and its long-term complications.

Comparison of insulin sensitivity measures in South Asians

OBJECTIVE

South Asians have increased visceral adiposity, insulin resistance and greater prevalence of type 2 diabetes and cardiovascular disease when compared to Caucasians of European origin. Surrogate markers of insulin resistance such as the composite insulin sensitivity (Matsuda) index correlate with glucose clamps in other populations, but ethnicity can affect these indices. We compared the Matsuda index, homeostasis model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), and triglyceride/HDL ratio to insulin sensitivity derived from euglycemic clamps in healthy South Asians and Caucasians.

MATERIALS/METHODS

Twenty-three healthy South Asians and 18 Caucasians matched for age (mean±SE=33.6±2.1 vs. 36.0±3.0 years) and BMI (25.2±1.1 vs. 24.6±0.9 kg/m(2)) underwent 75 g oral glucose tolerance test (OGTT), 2-h euglycemic hyperinsulinemic clamp (240 pmol·m(-2)·min(-1)), fasting lipid profile, and anthropometric measures.

RESULTS

South Asians had higher fasting insulin (41±5 vs. 21±2 pmol/l; p=0.002) and lower HDL-C (1.25±0.06 vs. 1.56±0.10 mmol/l; p=0.010), but similar fasting glucose (5.0±0.1 vs. 4.9±0.1 mmol/l) levels vs. Caucasians. South Asians had significantly decreased measures of insulin sensitivity derived from both the euglycemic clamp (24.9±1.3 vs. 41.4±1.9 μmol·kg(-1)·min(-1); p<0.0001) and OGTT (Matsuda Index 7.60±0.99 vs. 13.60±1.79; p=0.004). The Matsuda index correlated highly with clamp insulin sensitivity in South Asians (r=0.50; p=0.014) and Caucasians (r=0.47; p=0.046). HOMA-IR, QUICKI, and triglyceride/HDL ratio correlated with clamp values in South Asians, but not in Caucasians.

CONCLUSIONS

In South Asians, Matsuda index, HOMA-IR, QUICKI, and triglyceride/HDL ratio offer simple and valid surrogate measures of insulin sensitivity that can be employed in larger clinical or epidemiological studies in this ethnic group.

Association of female reproductive factors with body composition: the Framingham Heart Study

BACKGROUND

Identifying reproductive risk factors in women offers a life course approach to obesity and cardiovascular disease prevention. The association of female reproductive factors with measures of regional body fat distribution has not been comprehensively studied.

METHODS

We examined the association of female reproductive factors (age at menarche, parity, age at natural menopause, menopausal status) in association with body composition data from women who participated in the Offspring and the Third Generation Framingham Heart Study cohorts. Visceral adipose tissue (VAT) and sc adipose tissue (SAT) were measured volumetrically by multidetector computerized tomography. We modeled the relationship between each fat depot and female reproductive factors after adjusting for various factors such as age, smoking status, alcohol intake, physical activity index, hormone replacement therapy, and menopausal status.

RESULTS

Earlier age at menarche was associated with increased body mass index (BMI), waist circumference (WC), VAT, and SAT (P < 0.0001). This association of earlier menarche with adiposity measures was attenuated after adjusting for BMI (all P > 0.70). We observed no association between parity and all parameters of adiposity measurements (all P > 0.24). Similarly, age at natural menopause was not associated with measures of body composition. Despite higher mean BMI among the post- (BMI 27.3 kg/m(2)) compared with the premenopausal women (BMI 25.9 kg/m(2)) in an age-matched analysis, mean VAT was not different between the two groups (P = 0.30).

CONCLUSIONS

Earlier menarche is associated with overall obesity but not with VAT or SAT after accounting for measures of generalized adiposity. Parity and menopausal age were not associated with adiposity measures. Although postmenopausal women had increased BMI, VAT, and SAT, the association was predominantly due to age.

Immune modulation by Lacto-N-fucopentaose III in experimental autoimmune encephalomyelitis

Parasitic infections frequently lead to immune deviation or suppression. However, the application of specific parasitic molecules in regulating autoimmune responses remains to be explored. Here we report on the immune modulatory function of Lacto-N-fucopentaose III (LNFPIII), a schistosome glycan, in an animal model for multiple sclerosis. We found that LNFPIII treatment significantly reduced the severity of experimental autoimmune encephalomyelitis (EAE) and CNS inflammation, and skewed peripheral immune response to a Th2 dominant profile. Inflammatory monocytes (IMCs) purified from LNFPIII-treated mice had increased expression of nitric oxide synthase 2, and mediated T cell suppression. LNFPIII treatment also significantly increased mRNA expression of arginase-1, aldehyde dehydrogenase 1 subfamily A2, indoleamine 2,3-dioxygenase and heme oxygenase 1 in splenic IMCs. Furthermore, LNFPIII treatment significantly reduced trafficking of dendritic cells across brain endothelium in vitro. In summary, our study demonstrates that LNFPIII glycan treatment suppresses EAE by modulating both innate and T cell immune response.

Anti-CD3 mAb treatment cures PDL1-/-.NOD mice of diabetes but precipitates fatal myocarditis

Anti-CD3 mAb is an effective therapy that can reverse diabetes in NOD mice and has therapeutic potential in patients with type 1 diabetes (T1D). We administered anti-CD3 to PDL1-/-.NOD mice in order to determine whether this treatment would reverse the development of diabetes in these mice. Mice injected with anti-CD3 mAb neonatally were protected from T1D. However, all of these anti-CD3 mAb treated PDL1-/-.NOD mice developed a wasting disease between 12 and 20 weeks of age with sudden deterioration and weight loss, leading to death within 3-5 days of development of illness. Histology revealed severe inflammation in the heart and skeletal muscles. These results suggest that deficiency of PDL1 in NOD background has the potential to lead to immune-mediated tissue damage in organs other than the pancreas, but this cannot be appreciated in PDL1-/-.NOD mice as the mice develop T1D at an early age and die from diabetes prior to manifesting other autoimmune diseases.

Comparison of bone mineral density and body proportions between women with complete androgen insensitivity syndrome and women with gonadal dysgenesis

OBJECTIVES

To compare bone mineral density (BMD) and body proportions between women with complete androgen insensitivity syndrome (CAIS) and with gonadal dysgenesis (GD).

SETTING

Adult Disorders of Sexual Development and Ovarian Failure Clinics at University College London Hospitals.

DESIGN

Retrospective cross-sectional study of three groups of women aged 17-58 years with varying degrees of exposure to sex hormones and different combinations of sex chromosomes. Forty-six subjects had CAIS, 18 had GD and 46,XY (GD(XY)), and 25 had GD and 46,XX (GD(XX)). In addition, body proportions of subgroups of these women were analysed.

OUTCOME MEASURES

Oestrogen therapy, karyotype, anthropometry and BMD.

RESULTS

Height differed between groups (F ratio 5.2, P=0.007)), with GD(XX) women being the shortest (mean+/-s.d.: 1.66+/-0.10 m), GD(XY) women the tallest (1.74+/-0.09 m) and CAIS women were in-between (1.70+/-0.07 m). Delayed gonadectomy resulted in taller stature in CAIS women (P=0.011). The ratio of lower to upper body length in GD(XY) women was significantly (P=0.001) greater than that of CAIS women. Multivariate logistic regression analysis (adjusted for age and height) showed that among women with XY karyotype, GD(XY) women were 5.2 times (95% confidence interval (CI): 1.3-20.1, P=0.018) more likely than CAIS women to have a low hip BMD. This difference was not evident among women with GD of different karyotypes (P=0.938). Spinal BMD did not differ between subject groups. Further adjustment for oestrogen replacement did not alter these relationships.

CONCLUSIONS

Taller stature in late gonadectomised CAIS women suggests an oestrogen deficiency in these women prior to gonadectomy. Increased lower to upper body ratio in GD(XY) women compared with the other groups implies that these subjects have the greatest degree of oestrogen deficiency in puberty. Androgen rather than sex chromosomes may play an important role in cortical bone mineralisation in CAIS women, probably via estrogen receptor-alpha either directly or via aromatisation during critical periods of growth prior to gonadectomy.

Mechanisms of PDL1-mediated regulation of autoimmune diabetes

The PD-1-PDL1 pathway plays a critical role in regulating autoimmune diabetes as blockade or deficiency of PD-1 or PDL1 results in accelerated disease in NOD mice. We explored the cellular mechanisms involved in the regulation of these autoimmune responses by investigations involving various gene-deficient mice on the NOD background. Administration of blocking anti-PDL1 antibody to CD4+ T cell-deficient, CD8+ T cell-deficient and B cell-deficient mice demonstrated that PDL1-mediated regulation of autoreactive CD4+ and CD8+ T cells is critical for diabetes development. This concept was confirmed by adoptive transfer studies utilizing lymphocytes from BDC2.5 and 4.1 (CD4+) TCR transgenic mice and 8.3 (CD8+) TCR transgenic mice; efforts showing increased proliferation of both CD4+ and CD8+ T cells following PDL1 blockade in vivo. Furthermore, we observed that anti-PDL1-mediated acceleration is dependent upon events occurring in the pancreatic lymph nodes during early disease stages, but becomes independent of the pancreatic lymph nodes during later disease stages. These data provide strong evidence that PDL1 regulates autoimmune diabetes by limiting the expansion of CD4+ and CD8+ autoreactive T cells, and define the timing and locale of PDL1-mediated regulation of type 1 diabetes.

Role of ICOS pathway in autoimmune and alloimmune responses in NOD mice

Islet allografts are subject to alloimmune and autoimmune destruction when transplanted into autoimmune prone animals or humans. The ICOS-B7h pathway plays a role in alloimmune responses, but its function in autoimmunity against islet cells is controversial. We investigated the role of ICOS signaling in autoimmune and alloimmune responses in NOD mice. ICOS blockade prevents development of spontaneous disease in pre-diabetic NOD mice. Furthermore, while ICOS blockade prolongs graft survival in a fully mismatched non-autoimmune islet allograft model in C57BL/6 recipients, it has no beneficial effect in reversing diabetes in models of islet transplantation in NOD mice involving autoimmunity alone or both allo- and autoimmunity. Interestingly, ICOS blockade is effective in prolonging heart allograft (not subject to tissue-specific autoimmunity) survival in NOD mice. We conclude that in islet transplantation and autoimmune diabetes, ICOS blockade can be effective in inhibiting alloimmunity and preventing autoimmunity but is ineffective in inhibiting recurrence of autoimmunity.

The evolution of the immunobiology of co-stimulatory pathways: clinical implications

Co-stimulatory pathways are a prerequisite for the regulation of T-cell activation and tolerance. After the engagement of the T-cell receptor (TCR) to the major histocompatibility complex (MHC)/peptide complex, the co-stimulatory signals are critical to decide the outcome of the immune response. While positive co-stimulatory signals promote T-cell activation, negative signals delivered through inducible co-inhibitory receptors limit immune response, thereby regulating tolerance and autoimmunity. This review is intended not only to give an overview of the immunobiology of co-stimulatory pathways and their role in autoimmune diseases, but will also highlight the complexities and relevant issues one may have to think through to translate the target-ing of co-stimulatory pathways into successful therapeutic interventions.

Transplant tolerance through costimulation blockade - are we there yet?

Achieving a tolerant state specific to the transplanted graft without subjecting patients to the risks of non-specific immunosuppression is the goal of transplant immunologists. In spite of the success achieved with currently available immunosuppresive therapies over acute rejection, an ongoing T cell mediated alloimmune response still poses a major challenge to the health of an allograft through chronic rejection. Modulating these destructive alloresponses through T cell costimulation blockade is a promising area of interest. In this article, we review our current knowledge about the role of various positive and negative costimulatory pathways during an alloimmune response. The ultimate nature of that response depends on the complex interaction between these positive and negative costimulatory pathways. We discuss the progress that has been achieved so far, through targeting these individual pathways, their interaction with other costimulatory pathways and the currently available immunosuppressive agents in various organ transplant models.