Browsing by Subject "Type 1 diabetes (T1D)"

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    GDF15: a potential therapeutic target for type 1 diabetes
    (Taylor & Francis, 2022-01) Sarkar, Soumyadeep; Melchior, John T.; Henry, Hayden R.; Syed, Farooq; Mirmira, Raghavendra G.; Nakayasu, Ernesto S.; Metz, Thomas O.; Pediatrics, School of Medicine
    Introduction: Current treatment for type 1 diabetes (T1D) is centered around insulin supplementation to manage the effects of pancreatic β cell loss. GDF15 is a potential preventative therapy against T1D progression that could work to curb increasing disease incidence. Areas covered: This paper discusses the known actions of GDF15, a pleiotropic protein with metabolic, feeding, and immunomodulatory effects, connecting them to highlight the open opportunities for future research. The role of GDF15 in the prevention of insulitis and protection of pancreatic β cells against pro-inflammatory cytokine-mediated cellular stress are examined and the pharmacological promise of GDF15 and critical areas of future research are discussed. Expert opinion: GDF15 shows promise as a potential intervention but requires further development. Preclinical studies have shown poor efficacy, but this result may be confounded by the measurement of gross GDF15 instead of the active form. Additionally, the effect of GDF15 in the induction of anorexia and nausea-like behavior and short-half-life present significant challenges to its deployment, but a systems pharmacology approach paired with chronotherapy may provide a possible solution to therapy for this currently unpreventable disease.
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    Impact of Proinflammatory Cytokines on Alternative Splicing Patterns in Human Islets
    (American Diabetes Association, 2021) Wu, Wenting; Syed, Farooq; Simpson, Edward; Lee, Chih-Chun; Liu, Jing; Chang, Garrick; Dong, Chuanpeng; Seitz, Clayton; Eizirik, Decio L.; Mirmira, Raghavendra G.; Liu, Yunlong; Evans-Molina, Carmella; Medical and Molecular Genetics, School of Medicine
    Alternative splicing (AS) within the β-cell has been proposed as one potential pathway that may exacerbate autoimmunity and unveil novel immunogenic epitopes in type 1 diabetes (T1D). We used a computational strategy to prioritize pathogenic splicing events in human islets treated with interleukin-1β plus interferon-γ as an ex vivo model of T1D and coupled this analysis with a k-mer–based approach to predict RNA-binding proteins involved in AS. In total, 969 AS events were identified in cytokine-treated islets, with a majority (44.8%) involving a skipped exon. ExonImpact identified 129 events predicted to affect protein structure. AS occurred with high frequency in MHC class II–related mRNAs, and targeted quantitative PCR validated reduced inclusion of exon 5 in the MHC class II gene HLA-DMB. Single-molecule RNA fluorescence in situ hybridization confirmed increased HLA-DMB splicing in β-cells from human donors with established T1D and autoantibody positivity. Serine/arginine-rich splicing factor 2 was implicated in 37.2% of potentially pathogenic events, including exon 5 exclusion in HLA-DMB. Together, these data suggest that dynamic control of AS plays a role in the β-cell response to inflammatory signals during T1D evolution.
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    Islet Autoantibody Measurements from Dried Blood Spots on Filter Paper Strongly Correlate to Serum Levels
    (Plos, 2016-11-15) Simmons, Kimber M.; Alkanani, Aimon K.; McDaniel, Kristen A.; Goyne, Christopher; Miao, Dongmei; Zhao, Zhiyuan; Yu, Liping; Michels, Aaron W.; Department of Medicine, IU School of Medicine
    Type 1 diabetes (T1D) is increasing in incidence and predictable with measurement of serum islet autoantibodies (iAb) years prior to clinical disease onset. Identifying iAb positive individuals reduces diabetic ketoacidosis and identifies individuals for T1D prevention trials. However, large scale screening for iAb remains challenging as assays have varying sensitivities and specificities, insulin autoantibodies remain difficult to measure and venipuncture is generally required to obtain serum. We developed an approach to reliably measure all four major iAb, including insulin autoantibodies, from dried blood spots (DBS) on filter-paper. By spiking iAb positive serum into iAb negative whole blood in a dose titration, we optimized the conditions for autoantibody elution from filter paper as measured by fluid phase radioimmunoassays. After assessing stability of measuring iAb from DBS over time, we then screened iAb from DBS and the corresponding serum in new-onset T1D (n = 52), and controls (n = 72) which included first-degree relatives of T1D patients. iAb measured from eluted DBS in new-onset T1D strongly correlated with serum measurements (R2 = 0.96 for mIAA, GADA = 0.94, IA-2A = 0.85, ZnT8A = 0.82, p<0.01 for each autoantibody). There were no false positives in control subjects, and 5/6 with previously unknown iAb positivity in sera were detected using DBS. With further validation, measuring iAb from DBS can be a reliable method to screen for T1D risk.
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    Safety and effects of acetylated and butyrylated high amylose maize starch in recently diagnosed youths with type 1 diabetes; a Pilot Study
    (medRxiv, 2024-06-03) Ismail, Heba M.; Liu, Jianyun; Netherland, Michael, Jr.; Evans-Molina, Carmella; DiMeglio, Linda A.; Pediatrics, School of Medicine
    Acetylated and butyrylated high amylose starch (HAMS-AB) is a prebiotic shown to be effective in type 1 diabetes (T1D) prevention in mouse models and is safe in adults with established T1D. HAMS-AB alters the gut microbiome profile with increased bacterial fermenters that produce short chain fatty acids (SCFAs) with anti-inflammatory and immune-modulatory effects. We performed a pilot study using a cross-over design to assess the safety and efficacy of 4 weeks of oral HAMS-AB consumption by recently diagnosed (< 2 years of diagnosis) youths with T1D. Seven individuals completed the study. The mean±SD age was 15.0±1.2 years, diabetes duration 19.5±6.3 months, 5/7 were female and 4/7 were White, all with a BMI of < 85th%. The prebiotic was safe. Following prebiotic intake, gut microbiome changes were seen, including a notable increase in the relative abundance of fermenters such as Bifidobacterium and Faecalibacterium. Treatment was also associated with changes in bacterial functional pathways associated with either improved energy metabolism (upregulation of tyrosine metabolism) or anti-inflammatory effects (reduced geraniol degradation). There were no differences in stool SCFA levels. Plasma metabolites associated with improved glycemia, such as hippurate, were significantly increased after treatment and there were positive and significant changes in the immune regulatory function of mucosal associated invariant T cells. There was a significant decrease in the area under the curve glucose but not C-peptide, as measured during a mixed meal tolerance testing, following the prebiotic consumption. In summary, the prebiotic HAMS-AB was safe in adolescents with T1D and showed promising effects on the gut microbiome composition, function and immune regulatory function.
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    Small molecule glucagon release inhibitors with activity in human islets
    (Frontiers Media, 2023-04-19) Kalwat, Michael A.; Rodrigues-dos-Santos, Karina; Binns, Derk D.; Wei, Shuguang; Zhou, Anwu; Evans, Matthew R.; Posner, Bruce A.; Roth, Michael G.; Cobb, Melanie H.; Medicine, School of Medicine
    Purpose: Type 1 diabetes (T1D) accounts for an estimated 5% of all diabetes in the United States, afflicting over 1.25 million individuals. Maintaining long-term blood glucose control is the major goal for individuals with T1D. In T1D, insulin-secreting pancreatic islet β-cells are destroyed by the immune system, but glucagon-secreting islet α-cells survive. These remaining α-cells no longer respond properly to fluctuating blood glucose concentrations. Dysregulated α-cell function contributes to hyper- and hypoglycemia which can lead to macrovascular and microvascular complications. To this end, we sought to discover small molecules that suppress α-cell function for their potential as preclinical candidate compounds. Prior high-throughput screening identified a set of glucagon-suppressing compounds using a rodent α-cell line model, but these compounds were not validated in human systems. Results: Here, we dissociated and replated primary human islet cells and exposed them to 24 h treatment with this set of candidate glucagon-suppressing compounds. Glucagon accumulation in the medium was measured and we determined that compounds SW049164 and SW088799 exhibited significant activity. Candidate compounds were also counter-screened in our InsGLuc-MIN6 β-cell insulin secretion reporter assay. SW049164 and SW088799 had minimal impact on insulin release after a 24 h exposure. To further validate these hits, we treated intact human islets with a selection of the top candidates for 24 h. SW049164 and SW088799 significantly inhibited glucagon release into the medium without significantly altering whole islet glucagon or insulin content. In concentration-response curves SW088799 exhibited significant inhibition of glucagon release with an IC50 of 1.26 µM. Conclusion: Given the set of tested candidates were all top hits from the primary screen in rodent α-cells, this suggests some conservation of mechanism of action between human and rodents, at least for SW088799. Future structure-activity relationship studies of SW088799 may aid in elucidating its protein target(s) or enable its use as a tool compound to suppress α-cell activity in vitro.