ObjectivesReadily accessible human pancreatic beta cells that are functionally close to primary adult beta cells are a crucial model to better understand human beta cell physiology and develop new... Show moreObjectivesReadily accessible human pancreatic beta cells that are functionally close to primary adult beta cells are a crucial model to better understand human beta cell physiology and develop new treatments for diabetes. We here report the characterization of EndoC-βH5 cells, the latest in the EndoC-βH cell family.MethodsEndoC-βH5 cells were generated by integrative gene transfer of immortalizing transgenes hTERT and SV40 large T along with Herpes Simplex Virus-1 thymidine kinase into human fetal pancreas. Immortalizing transgenes were removed after amplification using CRE activation and remaining non-excized cells eliminated using ganciclovir. Resulting cells were distributed as ready to use EndoC-βH5 cells. We performed transcriptome, immunological and extensive functional assays.ResultsReady to use EndoC-βH5 cells display highly efficient glucose dependent insulin secretion. A robust 10-fold insulin secretion index was observed and reproduced in four independent laboratories across Europe. EndoC-βH5 cells secrete insulin in a dynamic manner in response to glucose and secretion is further potentiated by GIP and GLP-1 analogs. RNA-seq confirmed abundant expression of beta cell transcription factors and functional markers, including incretin receptors. Cytokines induce a gene expression signature of inflammatory pathways and antigen processing and presentation. Finally, modified HLA-A2 expressing EndoC-βH5 cells elicit specific A2-alloreactive CD8 T cell activation.ConclusionsEndoC-βH5 cells represent a unique storable and ready to use human pancreatic beta cell model with highly robust and reproducible features. Such cells are thus relevant for the study of beta cell function, screening and validation of new drugs, and development of disease models. Show less
Thomaidou, S.; Garcia, A.M.; Lange, S. de; Gan, J.; Slik, A.R. van der; Hoeben, R.C.; ... ; Zaldumbide, A. 2023
Aims/hypothesisThe inflammatory milieu characteristic of insulitis affects translation fidelity and generates defective ribosomal products (DRiPs) that participate in autoimmune beta cell... Show moreAims/hypothesisThe inflammatory milieu characteristic of insulitis affects translation fidelity and generates defective ribosomal products (DRiPs) that participate in autoimmune beta cell destruction in type 1 diabetes. Here, we studied the role of early innate cytokines (IFNα) and late immune adaptive events (IFNɣ) in insulin DRiP-derived peptide presentation to diabetogenic CD8+ T cells.MethodsSingle-cell transcriptomics of human pancreatic islets was used to study the composition of the (immuno)proteasome. Specific inhibition of the immunoproteasome catalytic subunits was achieved using siRNA, and antigenic peptide presentation at the cell surface of the human beta cell line EndoC-βH1 was monitored using peptide-specific CD8 T cells.ResultsWe found that IFNγ induces the expression of the PSMB10 transcript encoding the β2i catalytic subunit of the immunoproteasome in endocrine beta cells, revealing a critical role in insulin DRiP-derived peptide presentation to T cells. Moreover, we showed that PSMB10 is upregulated in a beta cell subset that is preferentially destroyed in the pancreases of individuals with type 1 diabetes.Conclusions/interpretationOur data highlight the role of the degradation machinery in beta cell immunogenicity and emphasise the need for evaluation of targeted immunoproteasome inhibitors to limit beta cell destruction in type 1 diabetes. Show less
Tienhoven, R. van; Kracht, M.J.L.; Slik, A.R. van der; Thomaidou, S.; Wolters, A.H.G.; Giepmans, B.G.; ... ; Roep, B.O. 2023
Aims/hypothesis Transcriptome analyses revealed insulin-gene-derived transcripts in non-beta endocrine islet cells. We studied alternative splicing of human INS mRNA in pancreatic islets. Methods:... Show moreAims/hypothesis Transcriptome analyses revealed insulin-gene-derived transcripts in non-beta endocrine islet cells. We studied alternative splicing of human INS mRNA in pancreatic islets. Methods: Alternative splicing of insulin pre-mRNA was determined by PCR analysis performed on human islet RNA and single-cell RNA-seq analysis. Antisera were generated to detect insulin variants in human pancreatic tissue using immunohistochemistry, electron microscopy and single-cell western blot to confirm the expression of insulin variants. Cytotoxic T lymphocyte (CTL) activation was determined by MIP-1 beta release. Results: We identified an alternatively spliced INS product. This variant encodes the complete insulin signal peptide and B chain and an alternative C-terminus that largely overlaps with a previously identified defective ribosomal product of INS. Immunohistochemical analysis revealed that the translation product of this INS-derived splice transcript was detectable in somatostatin-producing delta cells but not in beta cells; this was confirmed by light and electron microscopy. Expression of this alternatively spliced INS product activated preproinsulin-specific CTLs in vitro. The exclusive presence of this alternatively spliced INS product in delta cells may be explained by its clearance from beta cells by insulin-degrading enzyme capturing its insulin B chain fragment and a lack of insulin-degrading enzyme expression in delta cells. Conclusions/interpretation: Our data demonstrate that delta cells can express an INS product derived from alternative splicing, containing both the diabetogenic insulin signal peptide and B chain, in their secretory granules. We propose that this alternative INS product may play a role in islet autoimmunity and pathology, as well as endocrine or paracrine function or islet development and endocrine destiny, and transdifferentiation between endocrine cells. INS promoter activity is not confined to beta cells and should be used with care when assigning beta cell identity and selectivity. Show less
Szymczak, F.; Cohen-Fultheim, R.; Thomaidou, S.; Brachene, A.C. de; Castela, A.; Colli, M.; ... ; Zaldumbide, A. 2022
Introduction: Enterovirus infection has long been suspected as a possible trigger for type 1 diabetes. Upon infection, viral double-stranded RNA (dsRNA) is recognized by membrane and cytosolic... Show moreIntroduction: Enterovirus infection has long been suspected as a possible trigger for type 1 diabetes. Upon infection, viral double-stranded RNA (dsRNA) is recognized by membrane and cytosolic sensors that orchestrate type I interferon signaling and the recruitment of innate immune cells to the pancreatic islets. In this context, adenosine deaminase acting on RNA 1 (ADAR1) editing plays an important role in dampening the immune response by inducing adenosine mispairing, destabilizing the RNA duplexes and thus preventing excessive immune activation.Methods: Using high-throughput RNA sequencing data from human islets and EndoC-beta H1 cells exposed to IFN alpha or IFN gamma/IL1 beta, we evaluated the role of ADAR1 in human pancreatic beta cells and determined the impact of the type 1 diabetes pathophysiological environment on ADAR1-dependent RNA editing.Results: We show that both IFN alpha and IFN gamma/IL1 beta stimulation promote ADAR1 expression and increase the A-to-I RNA editing of Alu-Containing mRNAs in EndoC-beta H1 cells as well as in primary human islets.Discussion: We demonstrate that ADAR1 overexpression inhibits type I interferon response signaling, while ADAR1 silencing potentiates IFN alpha effects. In addition, ADAR1 overexpression triggers the generation of alternatively spliced mRNAs, highlighting a novel role for ADAR1 as a regulator of the beta cell transcriptome under inflammatory conditions. Show less
IFNa is a key regulator of the dialogue between pancreatic 0 cells and the immune system in early type 1 diabetes (T1D). IFNa up-regulates HLA class I expression in human 0 cells, fostering... Show moreIFNa is a key regulator of the dialogue between pancreatic 0 cells and the immune system in early type 1 diabetes (T1D). IFNa up-regulates HLA class I expression in human 0 cells, fostering autoantigen presentation to the immune system. We observed by bulk and single-cell RNA sequencing that exposure of human induced pluripotentderived islet-like cells to IFNa induces expression of HLA class I and of other genes involved in antigen presentation, including the transcriptional activator NLRC5. We next evaluated the global role of NLRC5 in human insulinproducing EndoC-0H1 and human islet cells by RNA sequencing and targeted gene/protein determination. NLRC5 regulates expression of HLA class I, antigen presentation-related genes, and chemokines. NLRC5 also mediates the effects of IFNa on alternative splicing, a generator of 0 cell neoantigens, suggesting that it is a central player of the effects of IFNa on 0 cells that contribute to trigger and amplify autoimmunity in T1D. Show less
Type 1 diabetes is a chronic autoimmune disease where the insulin producing beta cells of the pancreas are attacked by the immune system. Throughout this thesis, we challenged the classical view of... Show moreType 1 diabetes is a chronic autoimmune disease where the insulin producing beta cells of the pancreas are attacked by the immune system. Throughout this thesis, we challenged the classical view of T1D as a solely autoimmune disease and added to all the existing evidence indicating that beta cells by being inherently vulnerable to extracellular stress signals accumulate mistakes that may trigger an immune system with “good intentions” against a defective tissue. We studied the effect of an inflammatory environment on beta cell transcriptional, post transcriptional, translational, and antigen processing machinery, providing proofs that beta cells are not inert victims of the immune system but active players in their own destruction. This thesis clarifies the consequences of environment- and pathophysiology-induced changes on beta cells that lead to the development of autoimmunity in type 1 diabetes and provides new therapeutic targets to prevent formation or presentation of neoantigens. Show less
Thomaidou, S.; Slieker, R.C.; Slik, A.R. van der; Boom, J.; Mulder, F.; Munoz-Garcia, A.; ... ; Zaldumbide, A. 2021
Type 1 diabetes (T1D) is an autoimmune disease characterized by autoreactive T cell-mediated destruction of the insulin-producing pancreatic beta -cells. Increasing evidence suggest that the beta ... Show moreType 1 diabetes (T1D) is an autoimmune disease characterized by autoreactive T cell-mediated destruction of the insulin-producing pancreatic beta -cells. Increasing evidence suggest that the beta -cells themselves contribute to their own destruction by generating neoantigens through the production of aberrant or modified proteins that escape central tolerance. We recently demonstrated that ribosomal infidelity amplified by stress could lead to the generation of neoantigens in human beta -cells, emphasizing the participation of nonconventional translation events in autoimmunity, as occurring in cancer or virus-infected tissues. Using a transcriptome-wide profiling approach to map translation initiation start sites in human beta -cells under standard and inflammatory conditions, we identify a completely new set of polypeptides derived from noncanonical start sites and translation initiation within long noncoding RNA. Our data underline the extreme diversity of the beta -cell translatome and may reveal new functional biomarkers for beta -cell distress, disease prediction and progression, and therapeutic intervention in T1D. Show less
Roep, B.O.; Thomaidou, S.; Tienhoven, R. van; Zaldumbide, A. 2020
Type 1 diabetes mellitus is believed to result from destruction of the insulin-producing beta-cells in pancreatic islets that is mediated by autoimmune mechanisms. The classic view is that... Show moreType 1 diabetes mellitus is believed to result from destruction of the insulin-producing beta-cells in pancreatic islets that is mediated by autoimmune mechanisms. The classic view is that autoreactive T cells mistakenly destroy healthy ('innocent') beta-cells. We propose an alternative view in which the beta-cell is the key contributor to the disease. By their nature and function, beta-cells are prone to biosynthetic stress with limited measures for self-defence. beta-Cell stress provokes an immune attack that has considerable negative effects on the source of a vital hormone. This view would explain why immunotherapy at best delays progression of type 1 diabetes mellitus and points to opportunities to use therapies that revitalize beta-cells, in combination with immune intervention strategies, to reverse the disease. We present the case that dysfunction occurs in both the immune system and beta-cells, which provokes further dysfunction, and present the evidence leading to the consensus that islet autoimmunity is an essential component in the pathogenesis of type 1 diabetes mellitus. Next, we build the case for the beta-cell as the trigger of an autoimmune response, supported by analogies in cancer and antitumour immunity. Finally, we synthesize a model ('connecting the dots') in which both beta-cell stress and islet autoimmunity can be harnessed as targets for intervention strategies.This Review examines the evidence that beta-cells are active participants in the dialogue with the immune system during the development of type 1 diabetes mellitus. The authors suggest that therapies targeting beta-cell health, vitality and function might prove essential, in combination with immunotherapy, to change the course of events leading to beta-cell destruction. Show less
Thomaidou, S.; Kracht, M.J.L.; Slik, A. van der; Laban, S.; Koning, E.J. de; Carlotti, F.; ... ; Zaldumbide, A. 2020
The signal peptide of preproinsulin is a major source for HLA class I autoantigen epitopes implicated in CD8 T cell (CTL)-mediated beta -cell destruction in type 1 diabetes (T1D). Among them, the... Show moreThe signal peptide of preproinsulin is a major source for HLA class I autoantigen epitopes implicated in CD8 T cell (CTL)-mediated beta -cell destruction in type 1 diabetes (T1D). Among them, the 10-mer epitope located at the C-terminal end of the signal peptide was found to be the most prevalent in patients with recent-onset T1D. While the combined action of signal peptide peptidase and endoplasmic reticulum (ER) aminopeptidase 1 (ERAP1) is required for processing of the signal peptide, the mechanisms controlling signal peptide trimming and the contribution of the T1D inflammatory milieu on these mechanisms are unknown. Here, we show in human beta -cells that ER stress regulates ERAP1 gene expression at posttranscriptional level via the IRE1 alpha /miR-17-5p axis and demonstrate that inhibition of the IRE1 alpha activity impairs processing of preproinsulin signal peptide antigen and its recognition by specific autoreactive CTLs during inflammation. These results underscore the impact of ER stress in the increased visibility of beta -cells to the immune system and position the IRE1 alpha /miR-17 pathway as a central component in beta -cell destruction processes and as a potential target for the treatment of autoimmune T1D. Show less
