Publications by authors named "John P Mordes"

56 Publications

The Vbeta13 T Cell Receptor Monoclonal Antibody Reduces Hyaluronan and CD68+, CD3+, and CD8+ Cell Infiltrations to Delay Diabetes in Congenic BB DR Rats.

Front Endocrinol (Lausanne) 2021 16;12:629242. Epub 2021 Mar 16.

Department of Clinical Sciences, Lund University Clinical Research Center (CRC), Skåne University Hospital, Malmö, Sweden.

The depleting Vβ13a T cell receptor monoclonal antibody (mAb) 17D5 prevents both induced and spontaneous autoimmune diabetes in BB rats. Here it was tested in congenic DR rats, all of which spontaneously developed diabetes. Starting at 40 days of age, rats were injected once weekly with either saline, His42 Vβ16 mAb, or 17D5 mAb and monitored for hyperglycemia. Diabetes occurred in 100% (n = 5/5) of saline-treated rats (median age, 66 days; range 55-73), and in 100% (n = 6/6) of His42-treated rats (median age, 69 days; range 59-69). Diabetes occurred in fewer (n = 8/11, 73%) 17D5-treated rats at a later age (median 76 days, range 60-92). Three (27%) of the 17D5-treated rats were killed at 101-103 days of age without diabetes (17D5 no-diabetes rats). Survival analysis demonstrated that 17D5 mAb delayed diabetes onset. Saline- and His42-treated rats had severely distorted islets with substantial loss of insulin-positive cells. These rats exhibited prominent hyaluronan (HA) staining, with the intra-islet HA+ accumulations measuring 5,000 ± 2,400 µm and occupying 36 ± 12% of islet area, and severe (grade 4) insulitis with abundant infiltration by CD68+, CD3+, and CD8+ cells. The 17D5 mAb-treated rats with delayed diabetes onset exhibited less severe insulitis (predominantly grade 3). In contrast, the 17D5 no-diabetes rats had mostly normal islets, with insulin+ cells representing 76 ± 3% of islet cells. In these rats, the islet HA deposits were significantly smaller than in the diabetic rats; the intra-islet HA+ areas were 1,200 ± 300 µm and accounted for 8 ± 1% of islet area. Also, islet-associated CD68+ and CD3+ cells occurred less frequently (on average in 60 and 3% of the islets, respectively) than in the diabetes rats (present in >95% of the islets). No CD8+ cells were detected in islets in all 17D5 no-diabetes rats. We conclude that mAb 17D5 delayed diabetes in DR rats and markedly reduced expression of HA and concomitant infiltration of CD68+, CD3+, and CD8+ cells. Our findings underscore the importance of refining immune suppression in prevention or intervention clinical trials to use mAb reagents that are directed against specific T cell receptors.
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http://dx.doi.org/10.3389/fendo.2021.629242DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8010654PMC
March 2021

Genetic Variation Within the Gene Modulates Susceptibility to Type 1 Diabetes in HLA-DR3 Homozygotes.

Diabetes 2019 07 8;68(7):1523-1527. Epub 2019 Apr 8.

Division of Endocrinology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA

Type 1 diabetes (T1D) involves the interaction of multiple gene variants, environmental factors, and immunoregulatory dysfunction. Major T1D genetic risk loci encode HLA-DR and -DQ. Genetic heterogeneity and linkage disequilibrium in the highly polymorphic HLA region confound attempts to identify additional T1D susceptibility loci. To minimize HLA heterogeneity, T1D patients ( = 365) and control subjects ( = 668) homozygous for the HLA-DR3 high-risk haplotype were selected from multiple large T1D studies and examined to identify new T1D susceptibility loci using molecular inversion probe sequencing technology. We report that risk for T1D in HLA-DR3 homozygotes is increased significantly by a previously unreported haplotype of three single nucleotide polymorphisms (SNPs) within the first intron of The homozygous risk haplotype has an odds ratio of 4.65 relative to the protective homozygous haplotype in our sample. Individually, these SNPs reportedly function as "expression quantitative trait loci," modulating and - expression. From our analysis of available data, we conclude that the tri-SNP haplotype within may modulate class II expression, suggesting that increased T1D risk could be attributable to regulated expression of class II genes. These findings could help clarify the role of HLA in T1D susceptibility and improve diabetes risk assessment, particularly in high-risk HLA-DR3 homozygous individuals.
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http://dx.doi.org/10.2337/db18-1128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6609989PMC
July 2019

A Critical Role for the Type I Interferon Receptor in Virus-Induced Autoimmune Diabetes in Rats.

Diabetes 2017 Jan 7;66(1):145-157. Epub 2016 Oct 7.

Department of Medicine, University of Massachusetts Medical School, Worcester, MA

The pathogenesis of human type 1 diabetes, characterized by immune-mediated damage of insulin-producing β-cells of pancreatic islets, may involve viral infection. Essential components of the innate immune antiviral response, including type I interferon (IFN) and IFN receptor-mediated signaling pathways, are candidates for determining susceptibility to human type 1 diabetes. Numerous aspects of human type 1 diabetes pathogenesis are recapitulated in the LEW.1WR1 rat model. Diabetes can be induced in LEW.1WR1 weanling rats challenged with virus or with the viral mimetic polyinosinic:polycytidylic acid (poly I:C). We hypothesized that disrupting the cognate type I IFN receptor (type I IFN α/β receptor [IFNAR]) to interrupt IFN signaling would prevent or delay the development of virus-induced diabetes. We generated IFNAR1 subunit-deficient LEW.1WR1 rats using CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-associated protein 9) genome editing and confirmed functional disruption of the Ifnar1 gene. IFNAR1 deficiency significantly delayed the onset and frequency of diabetes and greatly reduced the intensity of insulitis after poly I:C treatment. The occurrence of Kilham rat virus-induced diabetes was also diminished in IFNAR1-deficient animals. These findings firmly establish that alterations in innate immunity influence the course of autoimmune diabetes and support the use of targeted strategies to limit or prevent the development of type 1 diabetes.
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http://dx.doi.org/10.2337/db16-0462DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5204313PMC
January 2017

Management status and its predictive factors in patients with type 2 diabetes in China: A Nationwide Multicenter Study: A Nationwide Multicenter Study.

Diabetes Metab Res Rev 2015 Nov;31(8):811-6

UMass Medical School, 364 Plantation Street LRB 222, Worcester.

Background: The prevalence of type 2 diabetes in China is increasing rapidly. Appropriate management of glycemia, blood pressure and dyslipidemia in this population is a major public health concern.

Objective: The aim of this study was to assess metabolic control including glycated hemoglobin A1c (HbA1c ), blood pressure (BP) and low density lipoprotein cholesterol (LDL-c), in a large sample of patients with type 2 diabetes in China and to identify factors that correlated with the achievement of HbA1c, BP and LDL-c goals (ABCs).

Method: A nationwide survey was conducted in 50 medical centres across China from April to July of 2010. Baseline information on demographics, medical history, HbA1c , BP and LDL-c levels were measured in 5961 patients with type 2 diabetes.

Results: Mean age, body mass index (BMI) and HbA1c were 59.5 ± 1.3 years, 24.5 ± 4.1 kg/m(2) and 8.3 ± 2.2%, respectively. With respect to generally accepted ABC treatment goals, 35.2% of participants had HbA1c <7%; 35.5% had BP < 140/80 mmHg, and 45.1% had LDL-c < 100 mg/dl. The proportion of patients who met all three targets was only 5.4%. Logistic regression revealed that smoking (P=0.000), higher BMI (P=0.001) and insulin use (P=0.000) were statistically significant predictors of failing to meet ABC targets.

Conclusion: The percentage of Chinese patients with type 2 diabetes who met recommended targets for HbA1c , BP and LDL-c in 2010 was low. Smoking, higher BMI and insulin use were the strongest determinants of failing to meet ABC targets.
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http://dx.doi.org/10.1002/dmrr.2757DOI Listing
November 2015

Medications for weight loss.

Curr Opin Endocrinol Diabetes Obes 2015 Apr;22(2):91-7

aDepartment of Medicine/Endocrinology, University of Massachusetts Medical School, Worcester, Massachusetts, USA bEndocrine and Diabetes Center, Jiangsu Province Hospital on Integration of Chinese and Western Medicine, Nanjing University of Traditional Chinese Medicine, Jiangsu Branch of China Academy of Chinese Medical Science, Nanjing, China.

Purpose Of Review: Overweight and obesity together with their comorbidities have become increasingly prevalent worldwide. The need for well tolerated, effective interventions has become increasingly urgent. Here we review the pharmacology, benefits, and risks of Western and Chinese medications used for weight loss.

Recent Findings: Lifestyle interventions for weight loss are efficacious, but have had limited long-term durability. Bariatric surgery is very effective for weight loss and reversal of type 2 diabetes mellitus (T2DM), but it is invasive and not consistently durable in all patients. Recent studies show that newer Western pharmaceuticals and some traditional Chinese medications may be effective for appropriate patients in need of weight loss.

Summary: New Western medications, notably lorcaserin, phentermine/topiramate, naltrexone/bupropion, and liraglutide, are more effective and possibly safer than older medications but have important side-effects. Chinese herbal medicines may have efficacy similar to that of older Western medications and with few side-effects, but data are limited. We suggest that for appropriate patients, in particular those with or at high risk for T2DM, the judicious use of these medications with lifestyle modification is justified. This may be particularly true in Asia where T2DM develops at a low BMI, though more data are needed to support this concept.
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http://dx.doi.org/10.1097/MED.0000000000000140DOI Listing
April 2015

Evaluation, Medical Therapy, and Course of Adult Persistent Hyperinsulinemic Hypoglycemia After Roux-en-Y Gastric Bypass Surgery: A Case Series.

Endocr Pract 2015 Mar;21(3):237-46

Division of Diabetes, University of Massachusetts Medical School, Worcester, Massachusetts.

Objective: To describe the evaluation and treatment of hyperinsulinemic hypoglycemia in adults who had undergone gastric bypass surgery. A small number of patients who undergo Roux-en-Y bypass surgery develop postprandial hypoglycemia in the absence of dumping. In some cases, such patients have been treated with pancreatectomy.

Methods: We report the demographics, diagnostic results, response to medical therapy, and subsequent course of 6 referral patients with post-Roux-en-Y gastric bypass hypoglycemia.

Results: Characteristic clinical and metabolic parameters consistent with hyperinsulinemic hypoglycemia were identified. Parameters were similar for both spontaneous and glucose-challenge-induced hypoglycemia. In the context of exclusively postprandial symptoms, simultaneous glucose ≤55 mg/dL, insulin ≥17 μU/mL, C peptide ≥3.0 ng/mL, and insulin to glucose ratio >0.3 were associated with Roux-en-Y gastric bypass hyperinsulinemic hypoglycemia. Five of 6 patients improved on therapy consisting of dietary modification plus either calcium channel blockade, acarbose, or both. Two patients have remained on therapy for 12 to 15 months. The nonresponder was atypical and had had hypoglycemic events for several decades. Three treated patients were subsequently observed to have undergone partial or complete remission from hypoglycemic episodes after 2 to 37 months of therapy. None of the 6 have undergone pancreatectomy, and none have evidence of insulinoma. Invasive diagnostic procedures were of limited utility.

Conclusion: In a subset of patients with post-Roux-en-Y gastric bypass hyperinsulinemic hypoglycemia, medical management can be efficacious and an alternative to partial pancreatectomy. In some cases, the disorder remits spontaneously.
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http://dx.doi.org/10.4158/EP14118.ORDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4754125PMC
March 2015

Autoantigen-induced focusing of Vβ13+ T cells precedes onset of autoimmune diabetes in the LEW.1WR1 rat.

Diabetes 2014 Feb 22;63(2):596-604. Epub 2013 Oct 22.

Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA.

The earliest events leading to autoimmune type 1 diabetes (T1D) are not known in any species. A T-cell receptor (TCR)-variable region, TCR-Vβ13, is required for susceptibility to autoimmune diabetes in rats, and selective depletion of Vβ13(+) T cells with an allele-specific monoclonal antibody prevents disease in multiple rat strains. To investigate the role of Vβ13 early in diabetes, we examined islet T-cell transcripts in susceptible (LEW.1WR1) and resistant (LEW.1W and Wistar Furth) strains induced with polyinosinic:polycytidylic acid. Vβ13(+) T cells displayed antigenic focusing in LEW.1WR1 islets 5 days postinduction and were characterized by a substantial decrease in complementarity determining region 3 diversity. This occurred prior to significant islet T-cell accumulation (day 7) or frank diabetes (days 10-14). Vβ13(+) transcripts increased in LEW.1WR1 islets during diabetes progression, but not in resistant rats. We also analyzed transcript clonality of rat TCR-Vα5, an ortholog of the dominant TCR-Vα chain found on insulin B:9-23-reactive T cells in nonobese diabetic rat islets. We observed clonal expansion of Vα5(+) transcripts in prediabetic LEW.1WR1 islets, suggesting that rat Vα5 is also an important component of islet autoantigen recognition. These data provide additional evidence that genome-encoded TCR sequences are important determinants of genetic susceptibility to T1D.
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http://dx.doi.org/10.2337/db13-0462DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3900547PMC
February 2014

The Missing Heritability in T1D and Potential New Targets for Prevention.

J Diabetes Res 2013 13;2013:737485. Epub 2013 Mar 13.

Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA.

Type 1 diabetes (T1D) is a T cell-mediated disease. It is strongly associated with susceptibility haplotypes within the major histocompatibility complex, but this association accounts for an estimated 50% of susceptibility. Other studies have identified as many as 50 additional susceptibility loci, but the effect of most is very modest (odds ratio (OR) <1.5). What accounts for the "missing heritability" is unknown and is often attributed to environmental factors. Here we review new data on the cognate ligand of MHC molecules, the T cell receptor (TCR). In rats, we found that one allele of a TCR variable gene, V β 13A, is strongly associated with T1D (OR >5) and that deletion of V β 13+ T cells prevents diabetes. A role for the TCR is also suspected in NOD mice, but TCR regions have not been associated with human T1D. To investigate this disparity, we tested the hypothesis in silico that previous studies of human T1D genetics were underpowered to detect MHC-contingent TCR susceptibility. We show that stratifying by MHC markedly increases statistical power to detect potential TCR susceptibility alleles. We suggest that the TCR regions are viable candidates for T1D susceptibility genes, could account for "missing heritability," and could be targets for prevention.
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http://dx.doi.org/10.1155/2013/737485DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3647582PMC
May 2013

Prevention of type 1 diabetes in the rat with an allele-specific anti-T-cell receptor antibody: Vβ13 as a therapeutic target and biomarker.

Diabetes 2012 May 24;61(5):1160-8. Epub 2012 Feb 24.

Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA.

In earlier studies of the Iddm14 diabetes susceptibility locus in the rat, we identified an allele of the T-cell receptor (TCR) β-chain, Tcrb-V13S1A1, as a candidate gene. To establish its importance, we treated susceptible rats with a depleting anti-rat Vβ13 monoclonal antibody and then exposed them to either polyinosinic:polycytidylic acid or a diabetogenic virus to induce diabetes. The overall frequency of diabetes in the controls was 74% (n = 50), compared with 17% (n = 30) in the anti-Vβ13-treated animals, with minimal islet pathology in nondiabetic treated animals. T cells isolated from islets on day 5 after starting induction showed a greater proportion of Vβ13(+) T cells than did peripheral lymph node T cells. Vβ13 transcripts recovered from day 5 islets revealed focused Jβ usage and less CDR3 diversity than did transcripts from peripheral Vβ13(+) T cells. CDR3 usage was not skewed in control Vβ16 CDR3 transcripts. Anti-rat Vβ13 antibody also prevented spontaneous diabetes in BBDP rats. The Iddm14 gene is likely to be Tcrb-V13, indicating that TCR β-chain usage is a determinant of susceptibility to autoimmune diabetes in rats. It may be possible to prevent autoimmune diabetes by targeting a limited element of the T-cell repertoire.
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http://dx.doi.org/10.2337/db11-0867DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3331757PMC
May 2012

Implications of using hemoglobin A1C for diagnosing diabetes mellitus.

Am J Med 2011 May;124(5):395-401

Division of Diabetes, University of Massachusetts Medical School, Worcester, USA.

Until 2010, the diagnosis of diabetes mellitus was based solely on glucose concentration, but the American Diabetes Association (ADA) recommendations now include a new criterion: hemoglobin A1C ≥6.5%. Because this change may have significant implications for diabetes diagnosis, we conducted a comprehensive literature review including peer-reviewed articles not referenced in the ADA report. We conclude that A1C and plasma glucose tests are frequently discordant for diagnosing diabetes. A1C ≥6.5% identifies fewer individuals as having diabetes than glucose-based criteria. Convenience of A1C test might increase the number of patients diagnosed, but this is unproven. Diagnostic cut-points for both glucose and A1C are based on consensus judgments regarding optimal sensitivity and specificity for the complications of hyperglycemia. A1C may not accurately reflect levels of glycemia in some situations, but in comparison with glucose measurements, it has greater analytic stability and less temporal variability. When choosing a diagnostic test for diabetes, the limitations of each choice must be understood. Clinical judgment and consideration of patient preference are required to appropriately select among the diagnostic alternatives.
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http://dx.doi.org/10.1016/j.amjmed.2010.11.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3086708PMC
May 2011

Haptoglobin as an early serum biomarker of virus-induced autoimmune type 1 diabetes in biobreeding diabetes resistant and LEW1.WR1 rats.

Exp Biol Med (Maywood) 2010 Nov;235(11):1328-37

Diabetes Division, University of Massachusetts, Worcester, MA 01605, USA.

Proteomic profiling of serum is a powerful technique to identify differentially expressed proteins that can serve as biomarkers predictive of disease onset. In this study, we utilized two-dimensional (2D) gel analysis followed by matrix-assisted-laser desorption/ionization time-of-flight mass spectrometry analysis to identify putative serum biomarkers for autoimmune type 1 diabetes (T1D) in biobreeding diabetes resistant (BBDR) rats induced to express the disease. Treatment with toll-like receptor 3 ligand, polyinosinic:polycytidilic acid (pIC), plus infection with Kilham rat virus (KRV), a rat parvovirus, results in nearly 100% of young BBDR rats becoming diabetic within 11-21 d. Sera collected from prediabetic rats at early time points following treatment with pIC + KRV were analyzed by 2D gel electrophoresis and compared with sera from control rats treated with phosphate-buffered saline, pIC alone or pIC + H1, a non-diabetogenic parvovirus. None of the latter three control treatments precipitates T1D. 2D gel analysis revealed that haptoglobin, an acute phase and hemoglobin scavenger protein, was differentially expressed in the sera of rats treated with pIC + KRV relative to control groups. These results were confirmed by Western blot and enzyme-linked immunosorbent assay studies, which further validated haptoglobin levels as being differentially increased in the sera of pIC + KRV-treated rats relative to controls during the first week following infection. Early elevations in serum haptoglobin were also observed in LEW1.WR1 rats that became diabetic following infection with rat cytomegalovirus. The identification and validation of haptoglobin as a putative serum biomarker for autoimmune T1D in rats now affords us the opportunity to test the validity of this protein as a biomarker for human T1D, particularly in those situations where viral infection is believed to precede the onset of disease.
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http://dx.doi.org/10.1258/ebm.2010.010150DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4172443PMC
November 2010

Identification of a serum-induced transcriptional signature associated with type 1 diabetes in the BioBreeding rat.

Diabetes 2010 Oct 3;59(10):2375-85. Epub 2010 Aug 3.

Max McGee National Research Center for Juvenile Diabetes, Department of Pediatrics at the Medical College of Wisconsin, the Children's Research Institute of Children’s Hospital of Wisconsin, and theHuman and Molecular Genetics Center, Milwaukee, Wisconsin, USA.

Objective: Inflammatory mediators associated with type 1 diabetes are dilute and difficult to measure in the periphery, necessitating development of more sensitive and informative biomarkers for studying diabetogenic mechanisms, assessing preonset risk, and monitoring therapeutic interventions.

Research Design And Methods: We previously utilized a novel bioassay in which human type 1 diabetes sera were used to induce a disease-specific transcriptional signature in unrelated, healthy peripheral blood mononuclear cells (PBMCs). Here, we apply this strategy to investigate the inflammatory state associated with type 1 diabetes in biobreeding (BB) rats.

Results: Consistent with their common susceptibility, sera of both spontaneously diabetic BB DRlyp/lyp and diabetes inducible BB DR+/+ rats induced transcription of cytokines, immune receptors, and signaling molecules in PBMCs of healthy donor rats compared with control sera. Like the human type 1 diabetes signature, the DRlyp/lyp signature, which is associated with progression to diabetes, was differentiated from that of the DR+/+ by induction of many interleukin (IL)-1-regulated genes. Supplementing cultures with an IL-1 receptor antagonist (IL-1Ra) modulated the DRlyp/lyp signature (P < 10(-6)), while administration of IL-1Ra to DRlyp/lyp rats delayed onset (P = 0.007), and sera of treated animals did not induce the characteristic signature. Consistent with the presence of immunoregulatory cells in DR+/+ rats was induction of a signature possessing negative regulators of transcription and inflammation.

Conclusions: Paralleling our human studies, serum signatures in BB rats reflect processes associated with progression to type 1 diabetes. Furthermore, these studies support the potential utility of this approach to detect changes in the inflammatory state during therapeutic intervention.
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http://dx.doi.org/10.2337/db10-0372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3279523PMC
October 2010

A novel role for the centrosomal protein, pericentrin, in regulation of insulin secretory vesicle docking in mouse pancreatic beta-cells.

PLoS One 2010 Jul 27;5(7):e11812. Epub 2010 Jul 27.

Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.

The centrosome is important for microtubule organization and cell cycle progression in animal cells. Recently, mutations in the centrosomal protein, pericentrin, have been linked to human microcephalic osteodysplastic primordial dwarfism (MOPD II), a rare genetic disease characterized by severe growth retardation and early onset of type 2 diabetes among other clinical manifestations. While the link between centrosomal and cell cycle defects may account for growth deficiencies, the mechanism linking pericentrin mutations with dysregulated glucose homeostasis and pre-pubertal onset of diabetes is unknown. In this report we observed abundant expression of pericentrin in quiescent pancreatic beta-cells of normal animals which led us to hypothesize that pericentrin may have a critical function in beta-cells distinct from its known role in regulating cell cycle progression. In addition to the typical centrosome localization, pericentrin was also enriched with secretory vesicles in the cytoplasm. Pericentrin overexpression in beta-cells resulted in aggregation of insulin-containing secretory vesicles with cytoplasmic, but not centrosomal, pericentriolar material and an increase in total levels of intracellular insulin. RNAi- mediated silencing of pericentrin in secretory beta-cells caused dysregulated secretory vesicle hypersecretion of insulin into the media. Together, these data suggest that pericentrin may regulate the intracellular distribution and secretion of insulin. Mice transplanted with pericentrin-depleted islets exhibited abnormal fasting hypoglycemia and inability to regulate blood glucose normally during a glucose challenge, which is consistent with our in vitro data. This previously unrecognized function for a centrosomal protein to mediate vesicle docking in secretory endocrine cells emphasizes the adaptability of these scaffolding proteins to regulate diverse cellular processes and identifies a novel target for modulating regulated protein secretion in disorders such as diabetes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0011812PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2910730PMC
July 2010

Infection with viruses from several families triggers autoimmune diabetes in LEW*1WR1 rats: prevention of diabetes by maternal immunization.

Diabetes 2010 Jan 30;59(1):110-8. Epub 2009 Sep 30.

BioMedical Research Models, Worcester, Massachusetts, USA.

Objective: The contribution of antecedent viral infection to the development of type 1 diabetes in humans is controversial. Using a newer rat model of the disease, we sought to 1) identify viruses capable of modulating diabetes penetrance, 2) identify conditions that increase or decrease the diabetogenicity of infection, and 3) determine whether maternal immunization would prevent diabetes.

Research Design And Methods: About 2% of LEW*1WR1 rats develop spontaneous autoimmune diabetes, but disease penetrance is much higher if weanling rats are exposed to environmental perturbants including Kilham rat virus (KRV). We compared KRV with other viruses for diabetogenic activity.

Results: Both KRV and rat cytomegalovirus (RCMV) induced diabetes in up to 60% of LEW*1WR1 rats, whereas H-1, vaccinia, and Coxsackie B4 viruses did not. Simultaneous inoculation of KRV and RCMV induced diabetes in 100% of animals. Pretreatment of rats with an activator of innate immunity increased the diabetogenicity of KRV but not RCMV and was associated with a moderate rate of diabetes after Coxsackie B4 and vaccinia virus infection. Inoculation of LEW*1WR1 dams with both KRV and RCMV prior to pregnancy protected weanling progeny from virus-induced diabetes in a virus-specific manner.

Conclusions: Exposure to viruses can affect the penetrance of autoimmune diabetes in genetically susceptible animals. The diabetogenicity of infection is virus specific and is modified by immunomodulation prior to inoculation. Maternal immunization protects weanlings from virus-induced diabetes, suggesting that modification of immune responses to infection could provide a means of preventing islet autoimmunity.
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http://dx.doi.org/10.2337/db09-0255DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2797911PMC
January 2010

Virus-induced autoimmune diabetes in the LEW.1WR1 rat requires Iddm14 and a genetic locus proximal to the major histocompatibility complex.

Diabetes 2009 Dec 31;58(12):2930-8. Epub 2009 Aug 31.

Department of Microbiology and Immunology, Center for Immunogenetics and Inflammatory Diseases, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.

Objective: To identify genes that confer susceptibility to autoimmune diabetes following viral infection in the LEW.1WR1 rat.

Research Design And Methods: About 2% of LEW.1WR1 rats develop spontaneous autoimmune diabetes. Immunological perturbants including viral infection increase both the frequency and tempo of diabetes onset. To identify diabetes susceptibility genes (LEW.1WR1 x WF), F2 rats were infected with Kilham rat virus following brief pretreatment with polyinosinic:polycytidylic acid. This treatment induces diabetes in 100% of parental LEW.1WR1 rats and 0% of parental WF rats. Linkage to diabetes was analyzed by genome-wide scanning.

Results: Among 182 F2 rats, 57 (31%) developed autoimmune diabetes after a mean latency of 16 days. All diabetic animals and approximately 20% of nondiabetic animals exhibited pancreatic insulitis. Genome-wide scanning revealed a requirement for the Iddm14 locus, long known to be required for diabetes in the BB rat. In addition, a new locus near the RT1 major histocompatibility complex (MHC) was found to be a major determinant of disease susceptibility. Interestingly, one gene linked to autoimmune diabetes in mouse and human, UBD, lies within this region.

Conclusions: The Iddm14 diabetes locus in the rat is a powerful determinant of disease penetrance in the LEW.1WR1 rat following viral infection. In addition, a locus near the MHC (Iddm37) conditions diabetes susceptibility in these animals. Other, as-yet-unidentified genes are required to convert latent susceptibility to overt diabetes. These data provide insight into the polygenic nature of autoimmune diabetes in the rat and the interplay of genetic and environmental factors underlying disease expression.
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http://dx.doi.org/10.2337/db09-0387DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2780864PMC
December 2009

Successful treatment of persistent hyperinsulinemic hypoglycemia with nifedipine in an adult patient.

Endocr Pract 2010 Jan-Feb;16(1):107-11

Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA.

Objective: To describe the successful treatment of severe noninsulinoma hyperinsulinemic hypoglycemia with use of a calcium channel blocking agent in an adult patient who had previously undergone a gastric bypass surgical procedure.

Methods: A 65-year-old woman who had undergone a gastric bypass surgical procedure 26 years earlier was hospitalized because of severe postprandial hypoglycemia. During and after hospitalization, the patient underwent assessment with conventional measurements of glucose, insulin, proinsulin, and C-peptide; toxicologic studies; magnetic resonance imaging studies of the pancreas; and determination of hepatic vein insulin concentrations after selective splanchnic artery calcium infusion.

Results: Metabolic variables were consistent with the diagnosis of hyperinsulinemic hypoglycemia. Magnetic resonance imaging revealed the presence of a side branch intraductal papillary mucinous tumor that had been stable for more than 1 year. The results of the calcium-stimulated insulin release study were consistent with nonlocalized hypersecretion of insulin. A trial of frequent small feedings failed to prevent hypoglycemia. On the basis of reports of successful treatment of childhood nesidioblastosis, the patient was then prescribed nifedipine, 30 mg daily. She has subsequently remained free of symptomatic hypoglycemia for 20 months.

Conclusion: A calcium channel blocking agent may be efficacious and a potential alternative to partial pancreatectomy in cases of noninsulinoma hyperinsulinemic hypoglycemia in adults.
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http://dx.doi.org/10.4158/EP09110.CRRDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3979460PMC
April 2010

CHOP mediates endoplasmic reticulum stress-induced apoptosis in Gimap5-deficient T cells.

PLoS One 2009 8;4(5):e5468. Epub 2009 May 8.

Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.

Gimap5 (GTPase of the immunity-associated protein 5) has been linked to the regulation of T cell survival, and polymorphisms in the human GIMAP5 gene associate with autoimmune disorders. The BioBreeding diabetes-prone (BBDP) rat has a mutation in the Gimap5 gene that leads to spontaneous apoptosis of peripheral T cells by an unknown mechanism. Because Gimap5 localizes to the endoplasmic reticulum (ER), we hypothesized that absence of functional Gimap5 protein initiates T cell death through disruptions in ER homeostasis. We observed increases in ER stress-associated chaperones in T cells but not thymocytes or B cells from Gimap5(-/-) BBDP rats. We then discovered that ER stress-induced apoptotic signaling through C/EBP-homologous protein (CHOP) occurs in Gimap5(-/-) T cells. Knockdown of CHOP by siRNA protected Gimap5(-/-) T cells from ER stress-induced apoptosis, thereby identifying a role for this cellular pathway in the T cell lymphopenia of the BBDP rat. These findings indicate a direct relationship between Gimap5 and the maintenance of ER homeostasis in the survival of T cells.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0005468PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2674944PMC
June 2009

Failure of alpha-galactosylceramide to prevent diabetes in virus-inducible models of type 1 diabetes in the rat.

In Vivo 2009 Mar-Apr;23(2):195-201

Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.

Background: Alpha-galactosylceramide (alpha-GalCer) is an invariant natural killer T (iNKT) cell ligand that prevents type 1 diabetes in NOD mice. However, alpha-GalCer can activate or suppress immune responses, raising concern about its potential use in human diabetes.

Materials And Methods: To evaluate this therapeutic issue further, BBDR and LEW.1WR1 rats were treated with Kilham rat virus (KRV) plus polyinosinic-polycytidylic acid, with or without alpha-GalCer, and followed for onset of diabetes.

Results: alpha-GalCer did not prevent diabetes in inducible rat models. To investigate this discrepancy, we analyzed iNKT cell function. Splenocytes stimulated with alpha-GalCer produced similar levels of IFNgamma in all rat strains, but less than mouse splenocytes. Rat splenocytes stimulated with alpha-GalCer preferentially produced IL-12, whereas mouse splenocytes preferentially produced IL-4.

Conclusion: alpha-GalCer elicits species-specific cytokine responses in iNKT cells. In humans with type 1 diabetes, differences in iNKT cell responses to stimulation with alpha-GalCer due to age, genetic variability and other factors may influence its therapeutic potential.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2718559PMC
July 2009

Depletion of the programmed death-1 receptor completely reverses established clonal anergy in CD4(+) T lymphocytes via an interleukin-2-dependent mechanism.

Cell Immunol 2009 23;256(1-2):86-91. Epub 2009 Feb 23.

University of Massachusetts Medical School, Worcester, 01655, USA.

Recent studies have implicated the cell surface receptor Programmed Death-1 (PD-1) in numerous models of T cell anergy, though the specific mechanisms by which the PD-1 signal maintains tolerance is not clear. We demonstrate that the depletion of PD-1 with siRNA results in a complete reversal of clonal anergy in the A.E7 T cell model, suggesting that the mechanism by which PD-1 maintains the anergic phenotype is a T-cell-intrinsic phenomenon, and not one dependent on other cell populations in vivo. We have also shown that the neutralization of IL-2 during restimulation abrogates the effect of PD-1 depletion, suggesting that tolerance mediated by PD-1 is wholly IL-2 dependent, and likewise intrinsic to the tolerized cells.
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http://dx.doi.org/10.1016/j.cellimm.2009.01.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2876711PMC
April 2009

Analysis of the rat Iddm14 diabetes susceptibility locus in multiple rat strains: identification of a susceptibility haplotype in the Tcrb-V locus.

Mamm Genome 2009 Mar 10;20(3):162-9. Epub 2009 Feb 10.

Department of Medicine, University of Massachusetts Medical School, Worcester, MA, 01655, USA.

Iddm14 (formerly Iddm4) is a non-MHC-linked genetic locus associated with autoimmune diabetes. Its effects have been well-documented in BB-derived rats in which diabetes is either induced by immunologic perturbation or occurs spontaneously. The role of Iddm14 in non-BB rat strains is unknown. Our goal was to extend the analysis of Iddm14 in new diabetes-susceptible strains and to identify candidate genes in the rat Iddm14 diabetes susceptibility locus that are common to these multiple diabetic strains. To determine if Iddm14 is important in strains other than BB, we first genotyped a (LEW.1WR1 x WF)F2 cohort in which diabetes was induced by perturbation with polyinosinic:polycytidylic acid. We found that Iddm14 is a major determinant of diabetes susceptibility in LEW.1WR1 rats. We then used nucleotide sequencing to establish a strain distribution pattern of polymorphisms (insertions, deletions, and single nucleotide polymorphisms [SNPs]) that predicts susceptibility to diabetes in a panel of inbred and congenic rats. Using the positional information from the congenic strains and the new linkage data, we identified a susceptibility haplotype in the T-cell receptor Vbeta chain (Tcrb-V) locus. This haplotype includes Tcrb-V13, which is identical in five susceptible strains but different in resistant WF and F344 rats. We conclude that Iddm14 is a powerful determinant of both spontaneous and induced autoimmune diabetes in multiple rat strains, and that Tcrb-V13 SNPs constitute a haplotype of gene elements that may be critical for autoimmune diabetes in rats.
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http://dx.doi.org/10.1007/s00335-009-9172-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3962255PMC
March 2009

Protein kinase C signaling during T cell activation induces the endoplasmic reticulum stress response.

Cell Stress Chaperones 2008 Dec 17;13(4):421-34. Epub 2008 Apr 17.

Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.

T cell receptor (TCR) ligation (signal one) in the presence of co-stimulation (signal two) results in downstream signals that increase protein production enabling naïve T cells to fully activate and gain effector function. Enhanced production of proteins by a cell requires an increase in endoplasmic reticulum (ER) chaperone expression, which is accomplished through activation of a cellular mechanism known as the ER stress response. The ER stress response is initiated during the cascade of events that occur for the activation of many cells; however, this process has not been comprehensively studied for T cell function. In this study, we used primary T cells and mice circulating TCR transgenic CD8(+) T cells to investigate ER chaperone expression in which TCR signaling was initiated in the presence or absence of co-stimulation. In the presence of both signals, in vitro and in vivo analyses demonstrated induction of the ER stress response, as evidenced by elevated expression of GRP78 and other ER chaperones. Unexpectedly, ER chaperones were also increased in T cells exposed only to signal one, a treatment known to cause T cells to enter the 'nonresponsive' states of anergy and tolerance. Treatment of T cells with an inhibitor to protein kinase C (PKC), a serine/threonine protein kinase found downstream of TCR signaling, indicated PKC is involved in the induction of the ER stress response during the T cell activation process, thus revealing a previously unknown role for this signaling protein in T cells. Collectively, these data suggest that induction of the ER stress response through PKC signaling is an important component for the preparation of a T cell response to antigen.
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http://dx.doi.org/10.1007/s12192-008-0038-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2673927PMC
December 2008

Type 1 IFN mediates cross-talk between innate and adaptive immunity that abrogates transplantation tolerance.

J Immunol 2007 Nov;179(10):6620-9

Department of Medicine, Division of Diabetes, University of Massachusetts Medical School, Worcester, MA 01655, USA.

TLR activation of innate immunity prevents the induction of transplantation tolerance and shortens skin allograft survival in mice treated with costimulation blockade. The mechanism by which TLR signaling mediates this effect has not been clear. We now report that administration of the TLR agonists LPS (TLR4) or polyinosinic:polycytidylic acid (TLR3) to mice treated with costimulation blockade prevents alloreactive CD8(+) T cell deletion, primes alloreactive CTLs, and shortens allograft survival. The TLR4- and MyD88-dependent pathways are required for LPS to shorten allograft survival, whereas polyinosinic:polycytidylic acid mediates its effects through a TLR3-independent pathway. These effects are all mediated by signaling through the type 1 IFN (IFN-alphabeta) receptor. Administration of IFN-beta recapitulates the detrimental effects of TLR agonists on transplantation tolerance. We conclude that the type 1 IFN generated as part of an innate immune response to TLR activation can in turn activate adaptive immune responses that abrogate transplantation tolerance. Blocking of type 1 IFN-dependent pathways in patients may improve allograft survival in the presence of exogenous TLR ligands.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3896082PMC
http://dx.doi.org/10.4049/jimmunol.179.10.6620DOI Listing
November 2007

A novel susceptibility locus on rat chromosome 8 affects spontaneous but not experimentally induced type 1 diabetes.

Diabetes 2007 Jun 27;56(6):1731-6. Epub 2007 Mar 27.

Department of Medicine, Sunnybrook and Women's College Health Sciences Centre Research Institute, University of Toronto, Toronto, Ontario, Canada.

Objective: The biobreeding diabetes-prone (BBDP) rat spontaneously develops type 1 diabetes. Two of the genetic factors contributing to this syndrome are the major histocompatibility complex (Iddm1) and a Gimap5 mutation (Iddm2) responsible for a T-lymphopenia. Susceptibility to experimentally induced type 1 diabetes is widespread among nonlymphopenic (wild-type Iddm2) rat strains provided they share the BBDP Iddm1 allele. The question follows as to whether spontaneous and experimentally induced type 1 diabetes share susceptibility loci besides Iddm1. Our objectives were to map a novel, serendipitously discovered Iddm locus, confirm its effects by developing congenic sublines, and assess its differential contribution to spontaneous and experimentally induced type 1 diabetes.

Research Design And Methods: An unexpected reduction in spontaneous type 1 diabetes incidence (86 to 31%, P < 0.0001) was observed in a BBDP line congenic for a Wistar Furth-derived allotypic marker, RT7 (chromosome 13). Genome-wide analysis revealed that, besides the RT7 locus, a Wistar Furth chromosome 8 fragment had also been introduced. The contribution of these intervals to diabetes resistance was assessed through linkage analysis using 134 F2 (BBDP x double congenic line) animals and a panel of congenic sublines. One of these sublines, resistant to spontaneous type 1 diabetes, was tested for susceptibility to experimentally induced type 1 diabetes.

Results: Both linkage analysis and congenic sublines mapped a novel locus (Iddm24) to the telomeric 10.34 Mb of chromosome 8, influencing cumulative incidence and age of onset of spontaneous type 1 diabetes but not insulitis nor experimentally induced type 1 diabetes.

Conclusions: This study has identified a type 1 diabetes susceptibility locus that appears to act after the development of insulitis and that regulates spontaneous type 1 diabetes exclusively.
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http://dx.doi.org/10.2337/db06-1790DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3987115PMC
June 2007

Refinement of the Iddm4 diabetes susceptibility locus reveals TCRVbeta4 as a candidate gene.

Ann N Y Acad Sci 2007 Apr 21;1103:128-31. Epub 2007 Mar 21.

Department of Microbiology and Immunology, Center for Immunogenetics and Inflammatory Diseases, Drexel University College of Medicine, Philadelphia, PA, USA.

Iddm4 is a dominant non-major histocompatibility complex (MHC) determinant of diabetes susceptibility in BBDR rats treated with poly I:C, plus depletion of regulatory T cells. In congenic MHC-identical normal WF rats, Iddm4(d) sensitively and specifically predicts induced diabetes. We report a new diabetes-susceptible subcongenic line that carries Iddm4 in a < 2.6 megabase interval. Candidate genes include the T cell receptor beta chain variable (TCRVbeta) family. We found that TCRVbeta4 in WF rats contains a stop codon, whereas 5/5 diabetes-susceptible rat strains express TCRVbeta4. We conclude that Iddm4-mediated diabetes resistance in rats may be due to a recessive protective mutation in TCRVbeta4.
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http://dx.doi.org/10.1196/annals.1394.020DOI Listing
April 2007

Development of new-generation HU-PBMC-NOD/SCID mice to study human islet alloreactivity.

Ann N Y Acad Sci 2007 Apr 21;1103:90-3. Epub 2007 Mar 21.

Diabetes Division, University of Massachusetts Medical School, 373 Plantation Street, Suite 218, Worcester, MA 01605, USA.

The use of "humanized" mice represents an appealing translational model for studies of the pathogenesis of immune-mediated diseases and for the evaluation of potential therapeutics. The utility of humanized mice depends on their ability to model the human immune system with high fidelity, and, in this respect, previous models have fallen short. The recently developed NOD-scid Il2rgamma(null) mouse, however, exhibits greatly enhanced ability to support the engraftment of human peripheral blood mononuclear cells. Herein, we describe the challenges of recapitulating human immunity in humanized mice and features of NOD-scid Il2rgamma(null) mice that help overcome them.
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http://dx.doi.org/10.1196/annals.1394.011DOI Listing
April 2007

TLR9-signaling pathways are involved in Kilham rat virus-induced autoimmune diabetes in the biobreeding diabetes-resistant rat.

J Immunol 2007 Jan;178(2):693-701

Department of Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA.

Viral infections are associated epidemiologically with the expression of type 1 diabetes in humans, but the mechanisms underlying this putative association are unknown. To investigate the role of viruses in diabetes, we used a model of viral induction of autoimmune diabetes in genetically susceptible biobreeding diabetes-resistant (BBDR) rats. BBDR rats do not develop diabetes in viral-Ab-free environments, but approximately 25% of animals infected with the parvovirus Kilham rat virus (KRV) develop autoimmune diabetes via a mechanism that does not involve beta cell infection. Using this model, we recently documented that TLR agonists synergize with KRV infection and increase disease penetrance. We now report that KRV itself activates innate immunity through TLR ligation. We show that KRV infection strongly stimulates BBDR splenocytes to produce the proinflammatory cytokines IL-6 and IL-12p40 but not TNF-alpha. KRV infection induces high levels of IL-12p40 by splenic B cells and Flt-3-ligand-induced bone marrow-derived dendritic cells (DCs) but only low levels of IL-12p40 production by thioglycolate-elicited peritoneal macrophages or GM-CSF plus IL-4-induced bone marrow-derived DCs. KRV-induced cytokine production is blocked by pharmacological inhibitors of protein kinase R and NF-kappaB. Genomic KRV DNA also induces BBDR splenocytes and Flt-3L-induced DCs from wild-type but not TLR9-deficient mice to produce IL-12p40; KRV-induced up-regulation of B lymphocytes can be blocked by TLR9 antagonists including inhibitory CpG and chloroquine. Administration of chloroquine to virus-infected BBDR rats decreases the incidence of diabetes and decreases blood levels of IL-12p40. Our data implicate the TLR9-signaling pathway in KRV-induced innate immune activation and autoimmune diabetes in the BBDR rat.
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http://dx.doi.org/10.4049/jimmunol.178.2.693DOI Listing
January 2007

A regulatory CD4+ T cell subset in the BB rat model of autoimmune diabetes expresses neither CD25 nor Foxp3.

J Immunol 2006 Dec;177(11):7820-32

Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA.

Biobreeding (BB) rats model type 1 autoimmune diabetes (T1D). BB diabetes-prone (BBDP) rats develop T1D spontaneously. BB diabetes-resistant (BBDR) rats develop T1D after immunological perturbations that include regulatory T cell (Treg) depletion plus administration of low doses of a TLR ligand, polyinosinic-polycytidylic acid. Using both models, we analyzed CD4+CD25+ and CD4+CD45RC- candidate rat Treg populations. In BBDR and control Wistar Furth rats, CD25+ T cells comprised 5-8% of CD4+ T cells. In vitro, rat CD4+CD25+ T cells were hyporesponsive and suppressed T cell proliferation in the absence of TGF-beta and IL-10, suggesting that they are natural Tregs. In contrast, CD4+CD45RC(-) T cells proliferated in vitro in response to mitogen and were not suppressive. Adoptive transfer of purified CD4+CD25+ BBDR T cells to prediabetic BBDP rats prevented diabetes in 80% of recipients. Surprisingly, CD4+CD45RC-CD25- T cells were equally protective. Quantitative studies in an adoptive cotransfer model confirmed the protective capability of both cell populations, but the latter was less potent on a per cell basis. The disease-suppressing CD4+CD45RC-CD25- population expressed PD-1 but not Foxp3, which was confined to CD4+CD25+ cells. We conclude that CD4+CD25+ cells in the BBDR rat act in vitro and in vivo as natural Tregs. In addition, another population that is CD4+CD45RC-CD25- also participates in the regulation of autoimmune diabetes.
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http://dx.doi.org/10.4049/jimmunol.177.11.7820DOI Listing
December 2006

Costimulatory blockade induces hyporesponsiveness in T cells that recognize alloantigen via indirect antigen presentation.

Transplantation 2006 Oct;82(8):1085-92

Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.

Background: Blockade of T cell costimulation by treatment with donor-specific transfusion (DST) and anti-CD154 monoclonal antibody (mAb) induces prolonged allograft survival in mice. This effect is due in part to deletion of host CD8 and CD4 T cells that recognize alloantigen by direct presentation. The fate of host CD4 T cells that recognize alloantigen by indirect presentation, however, is unclear.

Methods: We studied Tg361 TCR transgenic CD4 T cells that recognize alloantigen by indirect presentation. Carboxyfluorescein diacetate, succinimidyl ester-labeled Tg361 cells were adoptively transferred into syngeneic nontransgenic recipients and their fate in the peripheral blood, spleen, and lymph nodes following treatment with DST and anti-CD154 was analyzed.

Results: Treatment of mice with DST plus anti-CD154 mAb does not delete Tg361 CD4 T cells, but instead renders them hyporesponsive to rechallenge with alloantigen. Mice circulating hyporesponsive CD4 T cells also fail to reject skin allografts. The hyporesponsive state of the T cells is not reversed by the addition of interleukin-2, anti-CD28 mAb, or an agonistic anti-CD134 mAb in the presence of antigen. These T cells are capable of activation, however, as evidenced by in vitro proliferation in response to anti-CD3 mAb.

Conclusions: These results demonstrate that costimulation blockade can induce hyporesponsiveness of host CD4 T cells recognizing alloantigens by indirect presentation, thus prolonging graft survival by a mechanism that does not involve deletion of alloreactive T cells.
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http://dx.doi.org/10.1097/01.tp.0000235521.83772.29DOI Listing
October 2006

ART2, a T cell surface mono-ADP-ribosyltransferase, generates extracellular poly(ADP-ribose).

J Biol Chem 2006 Nov 24;281(44):33363-72. Epub 2006 Aug 24.

Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.

NAD functions in multiple aspects of cellular metabolism and signaling through enzymes that covalently transfer ADP-ribose from NAD to acceptor proteins, thereby altering their function. NAD is a substrate for two enzyme families, mono-ADP-ribosyltransferases (mARTs) and poly(ADP-ribose) polymerases (PARPs), that covalently transfer an ADP-ribose monomer or polymer, respectively, to acceptor proteins. ART2, a mART, is a phenotypic marker of immunoregulatory cells found on the surface of T lymphocytes, including intestinal intraepithelial lymphocytes (IELs). We have shown that the auto-ADP-ribosylation of the ART2.2 allelic protein is multimeric. Our backbone structural alignment of ART2 (two alleles of the rat art2 gene have been reported, for simplicity, the ART2.2 protein investigated in this study will be referred to as ART2) and PARP suggested that multimeric auto-ADP-ribosylation of ART2 may represent an ADP-ribose polymer, rather than multiple sites of mono-ADP-ribosylation. To investigate this, we used highly purified recombinant ART2 and demonstrated that ART2 catalyzes the formation of an ADP-ribose polymer by sequencing gel and by HPLC and MS/MS mass spectrometry identification of PR-AMP, a breakdown product specific to poly(ADP-ribose). Furthermore, we identified the site of ADP-ribose polymer attachment on ART2 as Arg-185, an arginine in a crucial loop of its catalytic core. We found that endogenous ART2 on IELs undergoes multimeric auto-ADP-ribosylation more efficiently than ART2 on peripheral T cells, suggesting that these distinct lymphocyte populations differ in their ART2 surface topology. Furthermore, ART2.2 IELs are more resistant to NAD-induced cell death than ART2.1 IELs that do not have multimeric auto-ADP-ribosylation activity. The data suggest that capability of polymerizing ADP-ribose may not be unique to PARPs and that poly(ADP-ribosylation), an established nuclear activity, may occur extracellularly and modulate cell function.
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http://dx.doi.org/10.1074/jbc.M607259200DOI Listing
November 2006

Anti-mouse CD154 antibody treatment facilitates generation of mixed xenogeneic rat hematopoietic chimerism, prevents wasting disease and prolongs xenograft survival in mice.

Xenotransplantation 2006 May;13(3):224-32

Division of Diabetes, University of Massachusetts Medical School, Worcester, MA, USA.

Background: The induction of xenogeneic hematopoietic chimerism is an attractive approach for overcoming the host response to xenografts, but establishing xenogeneic chimerism requires severe myeloablative conditioning of the recipient. The goal of this study was to determine if co-stimulation blockade would facilitate chimerism and xenograft tolerance in irradiation-conditioned concordant recipients.

Methods: Wistar Furth rat bone marrow (BM) cells were injected into irradiation-conditioned C57BL/6 mice with or without co-administration of anti-mouse CD154 monoclonal antibody (mAb). Chimerism was quantified by flow cytometry, and mice were transplanted with WF rat skin and islet xenografts.

Results: Blockade of CD40-CD154 interaction facilitated establishment of xenogeneic chimerism in mice conditioned with 600 cGy irradiation. Anti-CD154 mAb was not required for establishment of chimerism in mice treated with 700 cGy. However, mice irradiated with 700 cGy but not treated with anti-CD154 mAb developed a "graft-versus-host disease (GVHD)-like" wasting syndrome and died, irrespective of their development of chimerism. Xenogeneic chimeras established with irradiation and anti-CD154 mAb treatment exhibited prolonged skin and, in many cases, permanent islet xenograft survival. Chimerism was unstable and eventually lost in most recipients. Skin xenografts were rejected even in mice that remained chimeric, whereas most islet xenografts survived to the end of the observation period.

Conclusions: Blockade of host CD40-CD154 interaction facilitates the establishment of xenogeneic chimerism and prevents wasting disease and death. Chimerism permits prolonged xenograft survival, but chimerism generated in this way is unstable over time. Skin xenografts are eventually rejected, whereas most islet xenografts survive long term and perhaps permanently.
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http://dx.doi.org/10.1111/j.1399-3089.2006.00290.xDOI Listing
May 2006