[Show abstract][Hide abstract] ABSTRACT: Previously, we established a model in which physiologically adequate function of the autologous β cells was recovered in non-obese diabetic (NOD) mice after the onset of hyperglycemia by rendering them hemopoietic chimera. These mice were termed antea-diabetic. In the current study, we addressed the role of T regulatory (Treg) cells in the mechanisms mediating the restoration of euglycemia in the antea-diabetic NOD model. The data generated in this study demonstrated that the numbers of Treg cells were decreased in unmanipulated NOD mice, with the most profound deficiency detected in the pancreatic lymph nodes (PLNs). The impaired retention of the Treg cells in the PLNs correlated with the locally compromised profile of the chemokines involved in their trafficking, with the most prominent decrease observed in SDF-1. The amelioration of autoimmunity and restoration of euglycemia observed in the antea-diabetic mice was associated with restoration of the Treg cell population in the PLNs. These data indicate that the function of the SDF-1/CXCR4 axis and the retention of Treg cells in the PLNs have a potential role in diabetogenesis and in the amelioration of autoimmunity and β cell regeneration in the antea-diabetic model. We have demonstrated in the antea-diabetic mouse model that lifelong recovery of the β cells has a strong correlation with normalization of the Treg cell population in the PLNs. This finding offers new opportunities for testing the immunomodulatory regimens that promote accumulation of Treg cells in the PLNs as a therapeutic approach for type 1 diabetes (T1D).Cellular & Molecular Immunology advance online publication, 8 October 2012; doi:10.1038/cmi.2012.36.
[Show abstract][Hide abstract] ABSTRACT: Preventing activation of diabetogenic T cells is critical for delaying type 1 diabetes onset. The inhibitory molecule lymphocyte activation gene 3 (LAG-3) and metalloprotease tumor necrosis factor-α converting enzyme (TACE) work together to regulate TH1 responses. The aim of this study was to determine if regulating redox using a catalytic antioxidant (CA) could modulate TACE-mediated LAG-3 shedding to impede diabetogenic T-cell activation and progression to disease. A combination of in vitro experiments and in vivo analyses using NOD mouse strains was conducted to test the effect of redox modulation on LAG-3 shedding, TACE enzymatic function, and disease onset. Systemic treatment of NOD mice significantly delayed type 1 diabetes onset. Disease prevention correlated with decreased activation, proliferation, and effector function of diabetogenic T cells; reduced insulin-specific T-cell frequency; and enhanced LAG-3(+) cells. Redox modulation also affected TACE activation, diminishing LAG-3 cleavage. Furthermore, disease progression was monitored by measuring serum soluble LAG-3, which decreased in CA-treated mice. Therefore, affecting redox balance by CA treatment reduces the activation of diabetogenic T cells and impedes type 1 diabetes onset via decreasing T-cell effector function and LAG-3 cleavage. Moreover, soluble LAG-3 can serve as an early T-cell-specific biomarker for type 1 diabetes onset and immunomodulation.
[Show abstract][Hide abstract] ABSTRACT: Intracellular staining is a widely used flow cytometry (FCM)-based technique to detect the expression of cytoslio nucleic antigens. However, intracellular staining of cells expressing cytosolic fluorescent protein (FP) markers was proven to be problematic as significant loss of the FP-signal was routinely observed. Using splenocytes harvested from mice constitutively expressing the enhanced yellow fluorescent proteins (YFP) as a model, we modified the widely used intracellular staining protocol and successfully achieved simultaneous detection of both the nuclear proteins and YFP in T-regulatory cells. The improved protocol can be used to perform antibody-based intracellular characterization of FP-labeled target cells, while maintaining their fluorescent reporter signals for easy tracing and identification.
[Show abstract][Hide abstract] ABSTRACT: Reactive oxygen species (ROS) generated during hyperglycaemia are implicated in the development of diabetic vascular complications. High glucose increases oxidative stress in endothelial cells and induces apoptosis. A major source of ROS in endothelial cells exposed to glucose is the NAD(P)H oxidase enzyme. Several studies demonstrated that C-peptide, the product of proinsulin cleavage within the pancreatic beta cells, displays anti-inflammatory effects in certain models of vascular dysfunction. However, the molecular mechanism underlying this effect is unclear. We hypothesised that C-peptide reduces glucose-induced ROS generation by decreasing NAD(P)H oxidase activation and prevents apoptosis
Human aortic endothelial cells (HAEC) were exposed to 25 mmol/l glucose in the presence or absence of C-peptide and tested for protein quantity and activity of caspase-3 and other apoptosis markers by ELISA, TUNEL and immunoblotting. Intracellular ROS were measured by flow cytometry using the ROS sensitive dye chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H(2)-DCDFA). NAD(P)H oxidase activation was assayed by lucigenin. Membrane and cytoplasmic levels of the NAD(P)H subunit ras-related C3 botulinum toxin substrate 1 (rho family, small GTP binding protein Rac1) (RAC-1) and its GTPase activity were studied by immunoblotting and ELISA. RAC-1 (also known as RAC1) gene expression was investigated by quantitative real-time PCR.
C-peptide significantly decreased caspase-3 levels and activity and upregulated production of the anti-apoptotic factor B cell CLL/lymphoma 2 (BCL-2). Glucose-induced ROS production was quenched by C-peptide and this was associated with a decreased NAD(P)H oxidase activity and reduced RAC-1 membrane production and GTPase activity.
In glucose-exposed endothelial cells, C-peptide acts as an endogenous antioxidant molecule by reducing RAC-1 translocation to membrane and NAD(P)H oxidase activation. By preventing oxidative stress, C-peptide protects endothelial cells from glucose-induced apoptosis.
[Show abstract][Hide abstract] ABSTRACT: We have identified a novel interleukin (IL)-7-responsive T cell population [forkhead box P3 (FoxP3(+) ) CD4(+) CD25(+) CD127(+) ] that is comparably functionally suppressive to conventional FoxP3(+) CD4(+) CD25(+) regulatory T cells (T(regs) ). Although IL-2 is the most critical cytokine for thymic development of FoxP3(+) T(regs) , in the periphery other cytokines can be compensatory. CD25(+) CD127(+) T cells treated with IL-7 phenotypically 'matured' into the known 'classical' FoxP3(+) CD4(+) CD25(high) CD127(-) FoxP3(+) T(regs) . In freshly isolated splenocytes, the highest level of FoxP3 expression was found in CD127(+) CD25(+) T cells when compared with CD127(-) CD25(+) or CD127(+) CD25(-) cells. IL-7 treatment of CD4(+) CD25(+) T cells induced an increase in the accumulation of FoxP3 in the nucleus in vitro. IL-7-mediated CD25 cell surface up-regulation was accompanied by a concurrent down-regulation of CD127 in vitro. IL-7 treatment of the CD127(+) CD25(+) FoxP3(+) cells also resulted in up-regulation of cytotoxic T lymphocyte antigen 4 without any changes in CD45RA at the cell surface. Collectively, these data support emerging evidence that FoxP3(+) T cells expressing CD127 are comparably functionally suppressive to CD25(+) CD127(-) FoxP3(+) T cells. This IL-7-sensitive regulation of FoxP3(+) T(reg) phenotype could underlie one peripheral non-IL-2-dependent compensatory mechanism of T(reg) survival and functional activity, particularly for adaptive T(regs) in the control of autoimmunity or suppression of activated effector T cells.
[Show abstract][Hide abstract] ABSTRACT: This study was aimed at ascertaining the efficacy of antisense oligonucleotide-formulated microspheres to prevent type 1 diabetes and to reverse new-onset disease.
Microspheres carrying antisense oligonucleotides to CD40, CD80, and CD86 were delivered into NOD mice. Glycemia was monitored to determine disease prevention and reversal. In recipients that remained and/or became diabetes free, spleen and lymph node T-cells were enriched to determine the prevalence of Foxp3(+) putative regulatory T-cells (Treg cells). Splenocytes from diabetes-free microsphere-treated recipients were adoptively cotransferred with splenocytes from diabetic NOD mice into NOD-scid recipients. Live-animal in vivo imaging measured the microsphere accumulation pattern. To rule out nonspecific systemic immunosuppression, splenocytes from successfully treated recipients were pulsed with beta-cell antigen or ovalbumin or cocultured with allogeneic splenocytes.
The microspheres prevented type 1 diabetes and, most importantly, exhibited a capacity to reverse clinical hyperglycemia, suggesting reversal of new-onset disease. The microspheres augmented Foxp3(+) Treg cells and induced hyporesponsiveness to NOD-derived pancreatic beta-cell antigen, without compromising global immune responses to alloantigens and nominal antigens. T-cells from successfully treated mice suppressed adoptive transfer of disease by diabetogenic splenocytes into secondary immunodeficient recipients. Finally, microspheres accumulated within the pancreas and the spleen after either intraperitoneal or subcutaneous injection. Dendritic cells from spleen of the microsphere-treated mice exhibit decreased cell surface CD40, CD80, and CD86.
This novel microsphere formulation represents the first diabetes-suppressive and reversing nucleic acid vaccine that confers an immunoregulatory phenotype to endogenous dendritic cells.
[Show abstract][Hide abstract] ABSTRACT: Resources being amassed for genome-wide association (GWA) studies include "control databases" genotyped with a large-scale SNP array. How to use these databases effectively is an open question. We develop a method to match, by genetic ancestry, controls to affected individuals (cases). The impact of this method, especially for heterogeneous human populations, is to reduce the false-positive rate, inflate other spuriously small p values, and have little impact on the p values associated with true positive loci. Thus, it highlights true positives by downplaying false positives. We perform a GWA by matching Americans with type 1 diabetes (T1D) to controls from Germany. Despite the complex study design, these analyses identify numerous loci known to confer risk for T1D.
The American Journal of Human Genetics 03/2008; 82(2):453-63. · 11.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Epigenetic silencing of specific genes is associated with cancer progression. CpG islands are present at higher frequency in promoter regions, their methylation leading to gene underexpression. Pyrosequencing provides sequencing analysis of genetic markers, e.g., single nucleotide polymorphisms and DNA methylation. We investigated methylation levels of a spectrum of neoplastic breast lesions, ranging from hyperplasia to invasive carcinoma obtained from the same patient. Assays were designed to analyze promoter regions of RASSF1A, GSTP1, RARbeta, and E-cadherin. Methylation increased from normal to hyperplasia, the increase being significantly higher in invasive and in situ tumors for RASSF1A (p=0.00006 and p=0.009, respectively).
Cancer Letters 12/2007; 257(1):136-44. · 5.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Design of locus-specific primers for use during genetic analysis requires combining information from multiple sources and can be a time-consuming process when validating large numbers of assays. Data warehousing of genomic DNA sequences and genetic variations when coupled with software applications for optimizing the generation of locus-specific primers can increase the efficiency of assay development. Selection of oligonucleotide primers for PCR and Pyrosequencing (SOP3) software allows user-directed queries of warehoused data collected from the human and mouse genome sequencing projects. The software automates collection of DNA sequence flanking single-nucleotide polymorphisms (SNPs) as well as the incorporation of locus-associated functional information, such as whether the SNP occurs in an exon, intron, or untranslated region. SOP3 software accepts three types of user-directed input consisting of gene locus symbols, SNP reference sequence numbers, or chromosomal physical location. For human polymorphisms, SOP3 incorporates haplotype, ethnicity, and SNP validation attributes. The output is a list of oligonucleotide primers recommended for Pyrosequencing-based typing of genetic variations. SOP3 is available at the Division of Immunogenetics computational server found at http://imgen.ccbb.pitt.edu.
[Show abstract][Hide abstract] ABSTRACT: Successful transplantation of tissue during solid organ and bone marrow transplantation relies on accurate determination of the human leukocyte antigen (HLA) phenotype of the potential donor(s) and recipient. Matching donor with recipient for a kidney transplant generally means finding a six-antigen match by looking at each of two alleles at HLA-A, -B, and -DR loci. For bone marrow transplantation the HLA-C and -DQ alleles are also considered. Molecular techniques, including sequencing, are capable of precisely defining HLA alleles. Because of the large number of possible allelic combinations there are numerous ambiguities associated with heterozygous genotypes even when sequence-based typing protocols are used. Sequencing-by-synthesis methodology employed by Pyrosequencing represents an improvement when applied to HLA genotyping that allows resolution of many ambiguous allelic pairs. Out-of-phase sequencing of HLA alleles by Pyrosequencing can resolve cis/trans ambiguities that would otherwise require the sequencing of isolated cloned DNAs. Single-nucleotide polymorphism typing of HLA for the presence of specific variants is also beneficial for monitoring HLA-encoded genetic risk to autoimmune diseases, such as celiac disease, rheumatoid arthritis, and type 1 diabetes mellitus.
[Show abstract][Hide abstract] ABSTRACT: Dendritic cells can facilitate allograft survival and prevent autoimmunity via direct and indirect cell-mediated mechanisms. Recent studies demonstrate that immunoregulatory dendritic cells (iDCs) confer immune hyporesponsiveness in part through CD4(+) CD25(+) T regulatory cells (Tregs). Herein, we provide evidence to support the hypothesis that dendritic cells derived from NOD mice and engineered ex vivo to exhibit suppressed expression of the CD40, CD80, and CD86 costimulatory molecules motivate an increase in the prevalence of regulatory CD4(+) CD25(+) T-cells via interleukin (IL)-7. Unlike control dendritic cells, these dendritic cells expressed significant levels of IL-7. Exogenous addition of IL-7 to NOD T-cells did not promote expansion or proliferation, but instead selectively maintained the number of CD4(+) CD25(+) T-cells by inhibiting activation of apoptosis in these cells. In vitro, IL-7 receptor alpha-chain (IL-7Ralpha) was expressed at significantly higher levels on CD4(+) CD25(+) T-cells compared with CD4(+) CD25(-) T-cells irrespective of resting or stimulated state. In vivo, CD4(+) CD25(+) T-cells obtained from NOD-scid mice reconstituted with ex vivo engineered iDCs and NOD splenocytes expressed significantly higher levels of IL-7Ralpha compared with levels in the CD4(+) CD25(-) subset, especially in diabetes-suppressive dendritic cell-administered NOD-scid recipients. Taken together, our data suggest a novel mechanism by which iDCs delay autoimmunity through the CD4(+) CD25(+) Treg pathway and suggest IL-7 as a survival factor for these putative Tregs, which express the alpha-chain of its receptor at considerably higher levels than CD4(+) CD25(-) T-cells.
[Show abstract][Hide abstract] ABSTRACT: SOP3v2 is a database-driven graphical web-based application for facilitating genotyping assay design. SOP3v2 accepts data input in numerous forms, including gene names, reference sequence numbers and physical location. For each entry, the application presents a set of recommended forward and reverse PCR primers, along with a sequencing primer, which is optimized for sequence-based genotyping assays. SOP3v2-generated oligonucleotide primer trios enable analysis of single nucleotide polymorphisms (SNPs) as well as insertion/deletion polymorphisms found in genomic DNA. The application's database was generated by warehousing information from the National Center for Biotechnology Information (NCBI) dbSNP database, genomic DNA sequences from human and mouse, and LocusLink gene attribute information. Query results can be sorted by their biological relevance, such as nonsynonymous coding changes or physical location. Human polymorphism queries may specify ethnicity, haplotype and validation status. Primers are developed using SOP3v2's core algorithm for evaluating primer candidates through stability tests and are suitable for use with sequence-based genotyping methods requiring locus-specific amplification. The method has undergone laboratory validation. Of the SOP3v2-designed primer trios that were tested, a majority (>80%) have successfully produced genotyping data. The application may be accessed via the web at http://imgen.ccbb.pitt.edu/sop3v2.
Nucleic Acids Research 07/2005; 33(Web Server issue):W548-52. · 8.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: SOP3 is a web-based software tool for designing oligonucleotide primers for use in the analysis of single nucleotide polymorphisms (SNPs). Accessible via the Internet, the application is optimized for developing the PCR and sequencing primers that are necessary for Pyrosequencing. The application accepts as input gene name, SNP reference sequence number, or chromosomal nucleotide location. Output can be parsed by gene name, SNP reference number, heterozygosity value, location, chromosome, or function. The location of an individual polymorphism, such as an intron, exon, or 5' or 3' untranslated region is indicated, as are whether nucleotide changes in an exon are associated with a change in an amino acid sequence. SOP3 presents for each entry a set of forward and biotinylated reverse PCR primers as well as a sequencing primer for use during the analysis of SNPs by Pyrosequencing. Theoretical pyrograms for each allele are calculated and presented graphically. The method has been tested in the development of Pyrosequencing assays for determining SNPs and for deletion/insertion polymorphisms in the human genome. Of the SOP3-designed primer sets that were tested, a large majority of the primer sets have successfully produced PCR products and Pyrosequencing data.
[Show abstract][Hide abstract] ABSTRACT: Phenotypically "immature" dendritic cells (DCs), defined by low cell surface CD40, CD80, and CD86 can elicit host immune suppression in allotransplantation and autoimmunity. Herein, we report the most direct means of achieving phenotypic immaturity in NOD bone marrow-derived DCs aiming at preventing diabetes in syngeneic recipients. CD40, CD80, and CD86 cell surface molecules were specifically down-regulated by treating NOD DCs ex vivo with a mixture of antisense oligonucleotides targeting the CD40, CD80, and CD86 primary transcripts. The incidence of diabetes was significantly delayed by a single injection of the engineered NOD DCs into syngeneic recipients. Insulitis was absent in diabetes-free recipients and their splenic T cells proliferated in response to alloantigen. Engineered DC promoted an increased prevalence of CD4(+)CD25(+) T cells in NOD recipients at all ages examined and diabetes-free recipients exhibited significantly greater numbers of CD4(+)CD25(+) T cells compared with untreated NOD mice. In NOD-scid recipients, antisense-treated NOD DC promoted an increased prevalence of these putative regulatory T cells. Collectively, these data demonstrate that direct interference of cell surface expression of the major costimulatory molecules at the transcriptional level confers diabetes protection by promoting, in part, the proliferation and/or survival of regulatory T cells. This approach is a useful tool by which DC-mediated activation of regulatory T cells can be studied as well as a potential therapeutic option for type 1 diabetes.
The Journal of Immunology 11/2004; 173(7):4331-41. · 5.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Sequencing of alleles of the highly polymorphic, multiple loci HLA-DRB gene family was performed by pyrosequencing using purified DNA from the 11(th) International Histocompatibility Workshop human lymphoblastiod cell lines as well as genomic DNA isolated from blood samples obtained from healthy adult volunteers. Genomic DNA was prepared from donors whose blood had been stored either frozen or as dried blood spots. Pyrosequence-based typing was optimized for identifying alleles of the HLA-DRB1, -3, -4, and -5 genes. The procedure should be applicable to other HLA loci including the class I genes HLA-A and -B that, along with HLA-DRB, are crucial for histocompatibility matching of tissue antigens during transplantation. Computer simulation of pyrosequencing data suggest that alleles of HLA-DRB1, -3, -4, and -5 were readily identifiable by pyrosequencing as were their heterozygous allelic combinations. Pyrosequencing primers were designed to specifically sequence HLA loci of interest even in a background of other amplified, closely related sequences such as alleles of the pseudogene HLA-DRB6, -7, -8, and -9. Polymorphic residues of HLA-DRB genes were identified within each pyrosequencing reaction, obtained by 50 to 70 nucleotide read lengths. Heterozygous allelic combinations of HLA genes were analyzed and compared successfully to genotyping of alleles by sequence-specific oligonucleotide probe hybridization as well as allele specific polymerase chain reaction protocols. Pyrosequence-based typing is compatible with genotyping of allelic combinations expected from heterozygous individuals, resulting in nucleotide resolution of the highly polymorphic HLA system. Using a single pyrosequence instrument, complete typing of HLA-DRB genes can be performed daily on hundreds of individuals for high resolution histocompatibility genotyping studies.
Human Immunology 03/2004; 65(2):163-74. · 2.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In light of accumulating evidence that the endocrine pancreas has regenerative properties and that hematopoietic chimerism can abrogate destruction of beta cells in autoimmune diabetes, we addressed the question of whether recovery of physiologically adequate endogenous insulin regulation could be achieved in the nonobese diabetic (NOD) mice rendered allogeneic chimerae. Allogeneic bone marrow (BM) was transplanted into NOD mice at the preclinical and overtly clinical stages of the disease using lethal and nonlethal doses of radiation for recipient conditioning. Islets of Langerhans, syngeneic to the BM donors, were transplanted under kidney capsules of the overtly diabetic animals to sustain euglycemia for the time span required for recovery of the endogenous pancreas. Nephrectomies of the graft-bearing organs were performed 14 weeks later to confirm the restoration of endogenous insulin regulation. Reparative processes in the pancreata were assessed histologically and immunohistochemically. The level of chimerism in NOD recipients was evaluated by flow cytometric analysis. We have shown that as low as 1% of initial allogeneic chimerism can reverse the diabetogenic processes in islets of Langerhans in prediabetic NOD mice, and that restoration of endogenous beta cell function to physiologically sufficient levels is achievable even if the allogeneic BM transplantation is performed after the clinical onset of diabetes. If the same pattern of islet regeneration were shown in humans, induction of an autoimmunity-free status by establishment of a low level of chimerism, or other alternative means, might become a new therapy for type 1 diabetes.
[Show abstract][Hide abstract] ABSTRACT: DNA typing of alleles of the highly polymorphic HLA-DQBI gene was performed by Pyrosequencing using purified DNA from the 11th International Histocompatibility Workshop human cell lines and samples from the Children's Hospital of Pittsburgh registry of diabetics and their first-degree relatives. Pyrosequencing was optimized for genotyping exon 2 of the HLA-DQB1 gene, but the procedure should be applicable to other HLA loci. The 47 HLA-DQB1 alleles were readily identifiable, as were the 1,128 potential allelic heterozygous combinations. The method required PCR conditions that specifically amplified DQB1 but not the pseudogene, DQB2. The new method of pyrosequence-based typing can be performed in 96- or 384-well format. The 61 polymorphic residues of DQB1 exon 2 were identified within four pyrosequencing reactions, obtained by a 70-nucleotide read length in each reaction, in about an hour's time. Allelic combinations of HLA-DQB1 most frequentlyfound in the population of diabetics and their immediate family members were analyzed and successfully compared to typing of the DQB1 alleles by sequence-specific oligonucleotide probe protocols. Pyrosequence-based typing is compatible with genotyping of allelic combinations expected from heterozygous individuals, resulting in nucleotide resolution of the highly polymorphic HLA system. Using pyrosequencing, more than 750 sample wells can be processed in a working day, resulting in the identification of more than 50,000 bases.
[Show abstract][Hide abstract] ABSTRACT: The adaptation of allogeneic chimerism in treatment of autoimmune diabetes has been shown as a promising approach in numerous studies in both experimental and clinical settings. Establishment of hemopoietic chimerism in NOD mice is the most adequate animal model to study mechanisms involved in the multiple aspects of the curative effects of chimerism in autoimmunity-prone individuals. However, there are some discrepancies in the current literature for parameters and criteria used to characterize chimerism in the NOD model. This study was aimed to standardize the criteria for the different pathological stages of diabetogenesis in chimeric versus unmanipulated NOD mice. We report two well-defined scoring systems and a new Index N for the assessment of the pathological characteristics of diabetogenesis and GVHD in chimeric NOD mice. Also, we have demonstrated that, in the NOD model, recipient conditioning resulting in as low as 1% of chimerism is sufficient to promote engraftment of the BM donor-specific islets of Langerhans.