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Browsing by Author "Restrepo, Ivan A."
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Item Distinct gene expression pathways in islets from individuals with short‐ and long‐duration type 1 diabetes(Wiley, 2018) Mastracci, Teresa L.; Turatsinze, Jean-Valery; Book, Benita K.; Restrepo, Ivan A.; Pugia, Michael J.; Weibke, Eric A.; Pescovitz, Mark D.; Eizirik, Decio L.; Mirmira, Raghavendra G.; Biochemistry and Molecular Biology, School of MedicineAims Our current understanding of the pathogenesis of type 1 diabetes (T1D) arose, in large part, from studies using the non‐obese diabetic (NOD) mouse model. In the present study, we chose a human‐focused method to investigate T1D disease mechanisms and potential targets for therapeutic intervention by directly analysing human donor pancreatic islets from individuals with T1D. Materials and Methods We obtained islets from a young individual with T1D for 3 years and from an older individual with T1D for 27 years and performed unbiased functional genomic analysis by high‐depth RNA sequencing; the T1D islets were compared with islets isolated from 3 non‐diabetic donors. Results The islets procured from these T1D donors represent a unique opportunity to identify gene expression changes in islets after significantly different disease duration. Data analysis identified several inflammatory pathways up‐regulated in short‐duration disease, which notably included many components of innate immunity. As proof of concept for translation, one of the pathways, governed by IL‐23(p19), was selected for further study in NOD mice because of ongoing human trials of biologics against this target for different indications. A mouse monoclonal antibody directed against IL‐23(p19) when administered to NOD mice resulted in a significant reduction in incidence of diabetes. Conclusion While the sample size for this study is small, our data demonstrate that the direct analysis of human islets provides a greater understanding of human disease. These data, together with the analysis of an expanded cohort to be obtained by future collaborative efforts, might result in the identification of promising novel targets for translation into effective therapeutic interventions for human T1D, with the added benefit of repurposing known biologicals for use in different indications.Item Proinsulin and heat shock protein 90 as biomarkers of beta-cell stress in the early period after onset of type 1 diabetes(Elsevier, 2016-02) Watkins, Renecia A.; Evans-Molina, Carmella; Terrell, Jennifer K.; Day, Kathleen H.; Guindon, Lynette; Restrepo, Ivan A.; Mirmira, Raghavendra G.; Blum, Janice S.; Dimelglio, Linda A.; Department of Pediatrics, IU School of MedicineRapid evaluation of therapies designed to preserve β cells in persons with type 1 diabetes (T1D) is hampered by limited availability of sensitive β-cell health biomarkers. In particular, biomarkers elucidating the presence and degree of β-cell stress are needed. We characterized β-cell secretory activity and stress in 29 new-onset T1D subjects (10.6 ± 3.0 years, 55% male) at diagnosis and then 8.2 ± 1.2 weeks later at first clinic follow-up. We did comparisons with 16 matched healthy controls. We evaluated hemoglobin A1c (HbA1c), β-cell function (random C-peptide [C] and proinsulin [PI]), β-cell stress (PI:C ratio), and the β-cell stress marker heat shock protein (HSP)90 and examined these parameters' relationships with clinical and laboratory characteristics at diagnosis. Mean diagnosis HbA1c was 11.3% (100 mmol/mol) and 7.6% (60 mmol/mol) at follow-up. C-peptide was low at diagnosis (P < 0.001 vs controls) and increased at follow-up (P < 0.001) to comparable with controls. PI did not differ from controls at diagnosis but increased at follow-up (P = 0.003) signifying increased release of PI alongside improved insulin secretion. PI:C ratios and HSP90 concentrations were elevated at both time points. Younger subjects had lower C-peptide and greater PI, PI:C, and HSP90. We also examined islets isolated from prediabetic nonobese diabetic mice and found that HSP90 levels were increased ∼4-fold compared with those in islets isolated from matched CD1 controls, further substantiating HSP90 as a marker of β-cell stress in T1D. Our data indicate that β-cell stress can be assessed using PI:C and HSP90. This stress persists after T1D diagnosis. Therapeutic approaches to reduce β-cell stress in new-onset T1D should be considered.