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- Jonsson, Alexander, et al.
(författare)
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Transcriptional profiles of human islet and exocrine endothelial cells in subjects with or without impaired glucose metabolism
- 2020
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Ingår i: Scientific Reports. - BERLIN GERMANY : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- In experimental studies, pancreatic islet microvasculature is essential for islet endocrine function and mass, and islet vascular morphology is altered in diabetic subjects. Even so, almost no information is available concerning human islet microvascular endothelial cell (MVEC) physiology and gene expression. In this study, islets and exocrine pancreatic tissue were acquired from organ donors with normoglycemia or impaired glucose metabolism (IGM) immediately after islet isolation. Following single-cell dissociation, primary islet- and exocrine MVECs were obtained through fluorescence-activated cell sorting (FACS) and transcriptional profiles were generated using AmpliSeq. Multiple gene sets involved in general vascular development and extracellular matrix remodeling were enriched in islet MVEC. In exocrine MVEC samples, multiple enriched gene sets that relate to biosynthesis and biomolecule catabolism were found. No statistically significant enrichment was found in gene sets related to autophagy or endoplasmic reticulum (ER) stress. Although ample differences were found between islet- and exocrine tissue endothelial cells, no differences could be observed between normoglycemic donors and donors with IGM at gene or gene set level. Our data is consistent with active angiogenesis and vascular remodeling in human islets and support the notion of ongoing endocrine pancreas tissue repair and regeneration even in the adult human.
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| 2. |
- Neiman, Daniel, et al.
(författare)
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Multiplexing DNA methylation markers to detect circulating cell-free DNA derived from human pancreatic β cells
- 2020
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Ingår i: JCI Insight. - : American Society for Clinical Investigation. - 2379-3708. ; 5:14
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Tidskriftsartikel (refereegranskat)abstract
- It has been proposed that unmethylated insulin promoter fragments in plasma derive exclusively from β cells, reflect their recent demise, and can be used to assess β cell damage in type 1 diabetes. Herein we describe an ultrasensitive assay for detection of a β cell–specific DNA methylation signature, by simultaneous assessment of 6 DNA methylation markers, that identifies β cell DNA in mixtures containing as little as 0.03% β cell DNA (less than 1 β cell genome equivalent). Based on this assay, plasma from nondiabetic individuals (N = 218, aged 4–78 years) contained on average only 1 β cell genome equivalent/mL. As expected, cell-free DNA (cfDNA) from β cells was significantly elevated in islet transplant recipients shortly after transplantation. We also detected β cell cfDNA in a patient with KATP congenital hyperinsulinism, in which substantial β cell turnover is thought to occur. Strikingly, in contrast to previous reports, we observed no elevation of β cell–derived cfDNA in autoantibody-positive subjects at risk for type 1 diabetes (N = 32), individuals with recent-onset type 1 diabetes (<4 months, N = 92), or those with long-standing disease (>4 months, N = 38). We discuss the utility of sensitive β cell cfDNA analysis and potential explanations for the lack of a β cell cfDNA signal in type 1 diabetes.
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| 3. |
- Seiron, Peter, 1990-
(författare)
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Studies of the Pancreas: Implications for Type 1 Diabetes Aetiology
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Type 1 diabetes (T1D) is a disease of severe insulin deficiency through loss of β cells in the endocrine pancreas. The T1D dogma maintains that a precipitating event unleashes autoimmunity in at-risk individuals, often measured through autoantibodies against β cell antigens. This is followed by the death of β cells at the hands of autoreactive cytotoxic T cells. However, several findings have not found their place within this dogma; first, the immune cell infiltrate in islets is usually located outside the islets, and second, there is a pronounced impact on the exocrine pancreas with lower pancreatic weight and fibrosis surrounding the ducts. In this thesis, pancreata from human subjects without diabetes (ND) as well as with T1D or type 2 diabetes (T2D) have been examined in an attempt to clarify the aetiology of T1D.The consensus definition of insulitis (≥15 CD45+ cells per islet in ≥3 islets) was validated against ND pancreata. In paper I we show that this definition cannot sufficiently discriminate between the findings in T1D and T2D pancreata, due to an increase in exocrine infiltration in T2D, predominantly made up by macrophages. As exocrine infiltration is also a common finding in T1D, we propose a new definition. In paper II we found tissue resident memory T (TRM) cells in association to islets in both ND and T1D pancreata, and they made up a significant proportion of the insulitic lesion in T1D. Islets contain on average 60% β cells. In paper III we found that despite the seeming loss of this predominant cell type in the T1D islets, islet size remained the same. Instead, islet density was markedly reduced. The islets contained mainly α cells, some of which expressed PDX1, a transcription factor marker of β cells. In paper IV we examined pancreata from ND organ donors aged 1-81 years. For the first time, the islet transcriptome was analysed without prior enzymatic digestion of the tissue. We corroborate earlier findings of reduced cell cycle activity and increased senescence with increasing age, as well as present a hypothesis of how islet age might affect T1D.The findings in this thesis sprout an alternative hypothesis that disturbed establishment of β cells in early life, due to lower islet density and lower pancreatic weight, would lead to β cell stress as insulin demand increases with physical growth. However, as islets do not decrease in size, we suggest that the disappearance of β cells could be explained by transdifferentiation into glucagon-producing cells.
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| 4. |
- Skog, Oskar, Docent, PhD, 1981-, et al.
(författare)
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On the dynamics of the human endocrine pancreas and potential consequences for the development of type 1 diabetes
- 2020
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Ingår i: Acta Diabetologica. - : Springer Science and Business Media LLC. - 0940-5429 .- 1432-5233. ; 57:503-511
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the human islet life span, and beta-cell neogenesis is generally considered rare in adults. However, based on available data on beta-cell proliferation, calculations can be made suggesting that the dynamics of the endocrine pancreas is considerable even during adulthood, with islet neogenesis and a sustained increase in size of already formed islets. Islet-associated hemorrhages, frequently observed in most mammals including humans, could account for a considerable loss of islet parenchyma balancing the constant beta-cell proliferation. Notably, in subjects with type 1 diabetes, periductal accumulation of leukocytes and fibrosis is frequently observed, findings that are likely to negatively affect islet neogenesis from endocrine progenitor cells present in the periductal area. Impaired neogenesis would disrupt the balance, result in loss of islet mass, and eventually lead to beta-cell deficiency and compromised glucose metabolism, with increased islet workload and blood perfusion of remaining islets. These changes would impose initiation of a vicious circle further increasing the frequency of vascular events and hemorrhages within remaining islets until the patient eventually loses all beta-cells and becomes c-peptide negative. © 2019, The Author(s).
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