Unknown,Transcriptomics,Genomics,Proteomics

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Gene expression profiling of pancreatic islets in BioBreeding rats

ABSTRACT: Like humans, the NOD mouse and other diabetes susceptible rat strains, T1D in BB rats is dependent on the major histocompatibility complex (MHC, insulin dependent diabetes mellitus locus 1, Iddm1) located on chromosome 20. In rats this is the HLA-DQB1 homologue RT1-B, specifically the RT1u haplotype. Our studies employ congenic derivatives of the BB rat, the DRlyp/lyp and DR+/+ strains, which differ only by the 2 Mb lyp (lymphopenia, Iddm2) region on chromosome 4. TID in the lymphopenic DRlyp/lyp rat is spontaneous and onset occurs in 100% of animals during adolescence (65.3+/-6.3 days) due to a recessive mutation within GIMAP5 (GTPase, IMAP family member 5). Gimap5 is a mitochondrial GTP-binding protein necessary for post-thymic T cell survival. The spontaneously diabetic phenotype observed in DRlyp/lyp rats is thought to be elicited through deficiency in CD4+CD25+ TREG cells as T1D in lymphopenic BB rats can be rescued through adoptive transfer of this population. Genetic variation in GIMAP5 has been associated with the development of protein-tyrosine phosphatase-2 (IA-2) autoantibodies in human T1D [28] and is significantly associated with systemic lupus erythematosus (SLE). The non-lymphopenic DR+/+ strain possesses wild-type GIMAP5 alleles and does not develop spontaneous T1D, however, T1D is inducible through administration of lymphotoxic anti-RT6 monoclonal antibody and immune activating polyinosinic polycytidylic acid (poly I:C; a ligand of toll-like receptor 3), or through viral depletion of CD4+CD25+ regulatory T (TREG) cells. Such treatments do not induce T1D in the related Wistar-Furth (WF) rats and suggest the presence of an underlying diabetic predisposition in BB rats that is phenotypically manifested upon loss of immune regulation. DRlyp/lyp and DR+/+ rats possess characteristics that make them ideal for the identification of pathways relevant to the development of T1D since they possess absolute or conditional susceptibility to T1D. The Gimap-/- Iddm2 locus conveys upon DRlyp/lyp rats a deficiency in immune regulatory capacity and the spontaneous T1D phenotype. Consistent with the concept that autoimmunity involves both a lack of self-tolerance as well as target organ-specific factors, we have discovered that DRlyp/lyp and DR+/+ (BB) rats share an islet specific stress. This is reflected by the expression of immune mediators, including the chemokine eotaxin that recruits eosinophils, certain T cell subsets, dendritic cells, and mast cells, by islet Î² cells early in life, before infiltration of immune cells into the islet (insulitis). While BB and WF rats share Iddm1 (RT1u/u MHC), islet eotaxin expression in not observed in WF islets and thus is associated with the T1D susceptibility of BB rats. Further supporting the hypothesis that additional genetic factors, perhaps those working at the level of the pancreatic Î² cell, are necessary for the development of T1D are the observations that 1) The generation Fischer 344 (F344) rats either homozygous for Gimap5-/- or homozygous for both RT1u/u and Gimap5-/- fail to develop T1D; and 2) genetic crosses between BB rats and non diabetic strains have identified numerous Iddm loci independent of Iddm1 and Iddm2. In this study, using islet gene expression profiling, direct serum-level measurement, quantitative real-time PCR and targeted histological follow-up, we investigate pancreatic islet gene expression in BB rat at 5 weeks (+/-5 days) which is prior to insulitis in DRlyp/lyp rats. We compare DR+/+, JB++, JBlyp/lyp and DRlyp/lyp islet activity to that of WF and F344 rats to investigate any potential for reduction in capability to deal with oxidative stress in BB rats compared to non-BB and whether any differences in that capability map to known Iddm regions.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Ãke Lernmark

PROVIDER: E-GEOD-20214 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Like humans, the NOD mouse and other diabetes susceptible rat strains, T1D in BB rats is dependent on the major histocompatibility complex (MHC, insulin dependent diabetes mellitus locus 1, Iddm1) located on chromosome 20. In rats this is the HLA-DQB1 homologue RT1-B, specifically the RT1u haplotype. Our studies employ congenic derivatives of the BB rat, the DRlyp/lyp and DR+/+ strains, which differ only by the 2 Mb lyp (lymphopenia, Iddm2) region on chromosome 4. TID in the lymphopenic DRlyp/lyp rat is spontaneous and onset occurs in 100% of animals during adolescence (65.3+/-6.3 days) due to a recessive mutation within GIMAP5 (GTPase, IMAP family member 5). Gimap5 is a mitochondrial GTP-binding protein necessary for post-thymic T cell survival. The spontaneously diabetic phenotype observed in DRlyp/lyp rats is thought to be elicited through deficiency in CD4+CD25+ TREG cells as T1D in lymphopenic BB rats can be rescued through adoptive transfer of this population. Genetic variation in GIMAP5 has been associated with the development of protein-tyrosine phosphatase-2 (IA-2) autoantibodies in human T1D [28] and is significantly associated with systemic lupus erythematosus (SLE). The non-lymphopenic DR+/+ strain possesses wild-type GIMAP5 alleles and does not develop spontaneous T1D, however, T1D is inducible through administration of lymphotoxic anti-RT6 monoclonal antibody and immune activating polyinosinic polycytidylic acid (poly I:C; a ligand of toll-like receptor 3), or through viral depletion of CD4+CD25+ regulatory T (TREG) cells. Such treatments do not induce T1D in the related Wistar-Furth (WF) rats and suggest the presence of an underlying diabetic predisposition in BB rats that is phenotypically manifested upon loss of immune regulation. DRlyp/lyp and DR+/+ rats possess characteristics that make them ideal for the identification of pathways relevant to the development of T1D since they possess absolute or conditional susceptibility to T1D. The Gimap-/- Iddm2 locus conveys upon DRlyp/lyp rats a deficiency in immune regulatory capacity and the spontaneous T1D phenotype. Consistent with the concept that autoimmunity involves both a lack of self-tolerance as well as target organ-specific factors, we have discovered that DRlyp/lyp and DR+/+ (BB) rats share an islet specific stress. This is reflected by the expression of immune mediators, including the chemokine eotaxin that recruits eosinophils, certain T cell subsets, dendritic cells, and mast cells, by islet β cells early in life, before infiltration of immune cells into the islet (insulitis). While BB and WF rats share Iddm1 (RT1u/u MHC), islet eotaxin expression in not observed in WF islets and thus is associated with the T1D susceptibility of BB rats. Further supporting the hypothesis that additional genetic factors, perhaps those working at the level of the pancreatic β cell, are necessary for the development of T1D are the observations that 1) The generation Fischer 344 (F344) rats either homozygous for Gimap5-/- or homozygous for both RT1u/u and Gimap5-/- fail to develop T1D; and 2) genetic crosses between BB rats and non diabetic strains have identified numerous Iddm loci independent of Iddm1 and Iddm2.

Project description:Human type 1 diabetes (T1D) arises through autoimmunity towards the insulin-producing pancreatic β cells and is modeled by the BioBreeding (BB) rat. Factors associated with islet autoimmunity are dilute and difficult to directly measure in the periphery. Therefore, we previously utilized microarray-based bioassay where human T1D sera were used to induce a disease-specific gene expression signature in unrelated, healthy peripheral blood mononuclear cells (PBMC). Here we report that sera of both spontaneously diabetic BB DRlyp/lyp and diabetes inducible BB DR+/+ rats induce inflammatory signatures in healthy PBMC of non-diabetic Brown Norway (BN) rats, while allogeneic BN sera does not. Consistent with their common T1D susceptibility, transcriptional signatures of both BB sub-strains share identity, including cytokines, immune receptors and signaling molecules. However, like the human T1D signature, the DRlyp/lyp signature, which is associated with progression to diabetes, is differentiated from that of the DR+/+ by induction of many IL-1 regulated genes. Addition of IL-1RA to cultures significantly ablates the DRlyp/lyp signature. Daily treatment of DRlyp/lyp rats with human recombinant IL-1RA significantly delays onset and sera of treated animals do not induce the characteristic IL-1 signature. Consistent with the presence of immune regulation in DR+/+ rats is induction of a signature showing negative regulation of the NFκB pathway. This study supports prior human investigations of serum that reflect disease processes associated with progression to T1D and add to a growing body of evidence implicating the balance of IL-1 and IL-1RA as key factors influencing the severity and outcome of inflammatory responses. Experiment Overall Design: The induction of gene expression was accomplished by culturing the PBMCs of healthy day180 BN donor rats for 6 h at 37°C in 5% CO2 with a) 20% autologous BN plasma(10 replicates), b) allogeneic BN plasma (15 replicates), c) allogeneic DRlyp/lyp plasma (day 60, 4 replicates), or d) DR+/+ plasma (day 60, 4 replicates). Healthy BN PBMCs were also cultured with d60 DRlyp/lyp serum supplemented with IL-1RA (4 replicates) as well as autologous BN serum supplemented with IL-1B (4 replicates), to respectively block or induce IL-1 mediated gene expression. To determine if IL-1RA-treatment of DRlyp/lyp rats would result in modulation of the DRlyp/lyp signature, additional DRlyp/lyp rats were treated with hIL-1RA (n=6) or PBS (n=6). Rats were treated for 10 days, beginning at d30, then serum was collected at d40 and used to induce gene expression in PBMCs isolated from healthy d180 BN rats. Thus, there are a total of 53 chips being the addition of all the sample conditions mentioned above.

Project description:A need exists for biomarkers in T1D that can 1) sensitively and specifically detect disease-related immune activity prior to, and independent of, measurement of auto-antibodies towards islet cell antigens; 2) define immunopathological mechanisms; and 3) monitor changes in the inflammatory state associated with disease progression or response to therapeutic intervention. In an effort to fill this gap, we have applied a novel bioassay to both human and BB rat T1D whereby the complex milieu of inflammatory mediators present in plasma can be indirectly detected through their ability to drive transcription in peripheral blood mononuclear cells (PBMCs) drawn from healthy, unrelated donors. The resultant gene expressions are comprehensively measured with a microarray. In our human studies, we find that plasma of recent-onset T1D patients induces expression of a pro-inflammatory signature consisting in part of many interleukin-1 (IL-1) regulated genes related to immunological activation and immunocyte chemotaxis compared to unrelated healthy controls. This signature has been found to resolve in long-standing T1D subjects (>10 years post-onset), thus associating it with active autoimmunity. Importantly, this signature has been detected in pre-onset samples of progressors to T1D years prior to onset and prior to development of auto-antibodies directed towards islet antigens. In applying this approach to the BN rat, we observed that samples collected from both sub-strains at 60 days of age induced transcription of genes encoding cytokines, immune receptors, and signaling molecules consistent with a their shared susceptibility and immune activation. The DRlyp/lyp signature was differentiated from that of the DR+/+ by more robust induction of many interleukin (IL)-1M-bM-^@M-^Sregulated genes. Treatment of DRlyp/lyp rats with IL-1 receptor antagonist (IL-1RN) delayed onset and, in part, normalized the signature, suggesting that this approach may prove useful in monitoring the effect of therapeutic interventions in human T1D. Consistent with the presence of TREG cells in DR+/+ rats, we observed induction of a signature possessing negative regulators of transcription and inflammation. Fresh PBMCs of healthy Brown Norway (BN) rats (~180 days old males, to avoid variation introduced by estrous or pubertal status) were isolated by density gradient centrifugation. Transcription was induced by culturing PBMCs for 6 h at 37M-BM-0C in 5% CO2 with 20% allogeneic BN (healthy-unrelated control), DRlyp/lyp, or DR+/+ plasma [PMID 18209091]. DRlyp/lyp and DR+/+ Plasma was pooled at various ages (30, 40, 50, 60 days old) to represent timepoints prior to onset in the DRlyp/lyp strain.

Project description:Abstract; Human type 1 diabetes mellitus (T1DM) arises through autoimmune destruction of pancreatic Î² cells and is modeled in many respects by the lymphopenic and spontaneously diabetic BioBreeding (BB) DRlyp/lyp rat. Previously, pre-onset expression profiling of whole DRlyp/lyp pancreatic lymph nodes (PLN) revealed innate immune activity, specifically that of mast cells and eosinophils. Furthermore, we observed that pancreatic islets of DRlyp/lyp rats as well as those of diabetes-inducible BB DR+/+ rats potentially recruit innate cells through eotaxin expression. Here we determine that lifelong eotaxin expression begins before 40 days of life and localized specifically to Î² cells. In this report, we find PLN mast cells more abundant in DRlyp/lyp compared to related BB DR+/+ rats (2.1 +/-0.9% versus 0.9+/-0.4% of total cells, p<0.0001). DRlyp/lyp PLN mast cell gene expression profiling revealed an activated population and included significant overrepresentation of transcripts for mast cell protease 1, cationic trypsinogen, carboxypeptidase A, IL-5, and phospholipase CÎ³. In the DR+/+ rat, which develops T1DM upon depletion of TREG cells, mast cells displayed gene expression consistent with the negative regulation of degranulation, including significant overrepresentation of transcripts encoding tyrosine phosphatase SHP-1, lipid phosphatase SHIP, and E3 ubiquitin ligase c-Cbl. To recapitulate negative mast cell regulation observed in the DR+/+, we treated DRlyp/lyp rats with the mast cell âstabilizerâ cromolyn which significantly (p<0.05) delayed T1DM onset. These findings are consistent with a growing body of evidence in humans and animal models where a role for mast cells in the initiation and progression of autoimmune disease is emerging. Experiment Overall Design: Rat mast cells were isolated from freshly harvested, female d65 DR+/+ and DRlyp/lyp PLN (n=8 female animals per group) and total RNA was extracted using TRIzol Reagent (Invitrogen Life Technologies, Carlsbad CA). The GeneChipÂ® Rat Genome 230 2.0 array was selected for this study and possesses more than 31,000 probes sets, representing more than 17,734 unique UniGenes. Purified RNA (~50ng) was amplified using the Two-Cycle cDNA Synthesis Kit (Affymetrix, 900432) and cRNA was synthesized, labeled, fragmented, and hybridized to the Rat Genome 230 2.0 array in accordance to standard Affymetrix protocols (Affymetrix, Santa Clara, CA). Each RNA pool was analyzed in duplicate from independent RNA amplifications (4 arrays total). After hybridization, arrays were washed, stained with PE-conjugated streptavidin (Molecular Probes, Eugene, OR), and scanned

Project description:Type 1 diabetes (T1D) is an autoimmune disease characterized by destruction of the pancreatic β-cells. T1D pathogenesis has a strong genetic basis. However, in recent decades, the prevalence of high-risk HLA haplotypes among new diagnoses has declined, the age of onset has decreased, and T1D incidence has increased. These changes are consistent with increased environmental pressure and coincide with introduction of the Western diet, widespread antibiotic use and reduced breast feeding. These factors are thought to drive intestinal dysbiosis, increased gut permeability and systemic inflammation. Notably, our studies of T1D families and the BioBreeding (BB) rat have identified a peripheral inflammatory state associated with diabetes susceptibility that is consistent with microbial antigen exposure and pattern recognition receptor ligation. Lactiplantibacillus plantarum 299v (Lp299v), a probiotic strain, is reported to increase plasma and stool levels of anti-inflammatory short chain fatty acids (SCFA) and promote IL-10 signaling in colonic derived macrophages and T-cells. Here we investigated the effect of Lp299v supplement on T1D progression and inflammatory phenotypes in diabetes prone BB DRlyp/lyp rats. Rats were weaned at 21 days onto a normal cereal diet (ND) or a gluten-free hydrolyzed casein diet (HCD), with and without daily Lp299v supplementation. All DRlyp/lyp ND rats developed T1D by day 83 (mean time to onset of 62.8+/-7.9 days). DRlyp/lyp ND+Lp299v rats exhibited an insignificant delay in T1D onset (62.6+/-6.5 days), however 8% remained diabetes-free to day 130. Providing DRlyp/lyp rats HCD prevented T1D in 17% of rats (to age 130 days) and significantly delayed onset (mean time to onset 72.8+/-7.3 days, p<0.001). Providing DRlyp/lyp rats HCD+Lp299v prevented T1D in 25% of rats and more robustly delayed onset (mean time to onset 84.9 +/-14.3 days, p<0.001). While multiplex ELISA failed to detect significantly altered plasma cytokine/chemokine levels at 40 days of life, plasma induced transcription revealed greatest normalization of systemic inflammation in the HCD+Lp299v group. Plasma SCFA levels (propionate and butyrate, p<0.01) were elevated in the HCD+Lp299v group compared to the ND group. Global gene expression analysis of pancreatic islets was conducted at 40 days, prior to insulitis. Endoplasmic reticulum (ER) stress has been implicated in the formation of islet neoantigens that may underlie the initial loss of immune tolerance in T1D. Under one or both diets, Lp299v favorably modulated islet expression levels of pathways and transcripts related to inflammation and innate immunity (Cxcl9, Cxcl10), oxidative stress (Gsta1, Gsta4, Gstp1, Gstk1), as well as ER stress and unfolded protein response (Cirbp, Edem1, Hspa1a, Atf4). These ongoing studies add to a growing understanding that inherited susceptibility can be modulated by diet and microbiota.

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Gene expression profiling of pancreatic islets in BioBreeding rats

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