Biology subjects

Storling, J.

Publications and source records attributed to Storling, J..

4 recordsLinked to original sources

bioRxiv2024

Proinflammatory cytokine-induced alpha-cell impairment in human islet microtissues is partially restored by dual incretin receptor agonism

Aims/hypothesisIn type 1 diabetes, the counterregulatory glucagon response to low plasma glucose is impaired. The resulting increased risk of hypoglycaemia necessitates novel strategies to ameliorate alpha-cell impairment. Here, we aimed to establish an in vitro model of alpha-cell impairment in type 1 diabetes using human islet microtissues (MTs) exposed to proinflammatory cytokines. Additionally, we investigated the therapeutic potential of incretin receptor agonists in improving alpha-cell responses to low glucose. MethodsHuman islet MTs were exposed to proinflammatory cytokines (IL-1{beta}, IFN-{gamma}, and TNF-) for 1 day (short-term) and 6 days (long-term). Alpha-cell function was assessed by sequential glucose-dependent secretion assays at 2.8 and 16.7 mmol/l glucose, followed by glucagon measurements. Additional evaluations included ATP content, caspase-3/7 activity, chemokine secretion, and expression of islet transcription factors and hormones. The effects of incretin receptor agonist treatment (glucose-dependent insulinotropic polypeptide (GIP) analogue [D-Ala2]-GIP {+/-} liraglutide) alongside or after cytokine exposure were also investigated, focusing on low glucose-dependent glucagon secretion. ResultsShort-term cytokine exposure increased glucagon secretion at both 2.8 and 16.7 mmol/l glucose. In contrast, long-term cytokine exposure caused dose-dependent suppression of glucagon secretion at 2.8 mmol/l glucose, resembling a type 1 diabetes phenotype. Long-term cytokine exposure also diminished somatostatin secretion, reduced ATP content, increased caspase 3/7 activity, and decreased islet transcription factor and hormone expression. Despite cytokine-induced impairment, alpha cells partially retained secretory capacity to L-arginine stimulation. Treatment with incretin receptor agonists during long-term cytokine exposure did not prevent alpha-cell impairment. However, acute treatment with [D-Ala2]-GIP {+/-} liraglutide or the single-molecule dual agonist tirzepatide partially restored glucagon secretion at low glucose. Conclusions/interpretationLong-term cytokine exposure of human islet MTs impaired glucagon secretion to low glucose, creating a type 1 diabetes alpha-cell phenotype. This cytokine-induced alpha-cell impairment was partially restored by [D-Ala2]-GIP {+/-} liraglutide and tirzepatide, respectively. Research in contextO_ST_ABSWhat is already known about this subject?C_ST_ABSO_LIThe counterregulatory alpha-cell response to low glucose is impaired in type 1 diabetes, increasing the risk of hypoglycaemia. C_LIO_LILimited translatability of rodent islet findings highlights the need for human islet models. C_LIO_LIActions of the incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) have mainly been studied in the context of type 2 diabetes and hyperglycaemia but less in type 1 diabetes and hypoglycaemia. C_LI What is the key question?O_LICan alpha-cell impairment in type 1 diabetes be modelled in vitro by exposing human islet microtissues (MTs) to proinflammatory cytokines, and could incretins protect against this? C_LI What are the new findings?O_LILong-term (6-day) exposure to proinflammatory cytokines produces a type 1 diabetes phenotype of alpha-cell impairment to low glucose in islet MTs C_LIO_LIAcute dual treatment with incretin receptor agonists partially restored glucose-dependent glucagon secretion in cytokine-exposed islet MTs -- an effect mainly carried by GIP receptor agonism and not opposed by GLP-1 receptor agonism. C_LI How might this impact on clinical practice in the foreseeable future?O_LIInvestigating incretin receptor agonists in a preclinical in vitro model of alpha-cell impairment may reveal their potential and fast-track their use as safeguards against hypoglycaemia in type 1 diabetes. C_LI

cell biology↗

bioRxiv2024

Exploring the functional, protective, and transcriptomic effects of GIP on cytokine-exposed human pancreatic islets and EndoC-βH5 cells

Immune-mediated beta-cell destruction and lack of alpha-cell responsiveness to hypoglycaemia are hallmarks of type 1 diabetes pathology. The incretin hormone glucose-dependent insulinotropic polypeptide (GIP) may hold therapeutic potential for type 1 diabetes due to its insulinotropic and glucagonotropic effects, as well as its beta-cell protective effects shown in rodent islets. Here, we examined the functional, protective, and transcriptomic effects of GIP treatment upon diabetogenic cytokine exposure to interleukin (IL)-1{beta} {+/-} interferon (IFN)-{gamma} in human EndoC-{beta}H5 beta cells and isolated human islets, respectively. GIP dose-dependently augmented glucose-stimulated insulin secretion from EndoC-{beta}H5 cells and increased insulin and glucagon secretion from human islets during high and low glucose concentrations, respectively. The insulinotropic effect of GIP in EndoC-{beta}H5 cells was abrogated by KN-93, an inhibitor of calcium/calmodulin-dependent protein kinase 2 (CaMK2). GIP did not prevent cytokine-induced apoptosis or cytokine-induced functional impairment of human EndoC-{beta}H5 cells. GIP also did not prevent cytokine-induced apoptosis in human islets. GIP treatment of human islets with or without cytokines for 24 hours did not significantly impact the transcriptome. GIP potentiated cytokine-induced secretion of IL-10 and c-c motif chemokine ligand (CCL)-2 from human islets while decreasing the secretion of c-x-c motif chemokine ligand (CXCL)-8. In EndoC-{beta}H5 cells, GIP reduced IFN-{gamma}-induced secretion of tumor necrosis factor (TNF)-, IL-2, IL-6, and IL-10 but increased the secretion of CXCL8, CCL2, CCL4, and CCL11. In conclusion, our results suggest that the insulinotropic effect of GIP is CaMK2-dependent. Furthermore, our results indicate that GIP does not provide substantial cytoprotective effects against diabetogenic cytokine challenge or significantly modulate the transcriptome of human islets when applied at a supraphysiological level. GIP may, however, still exert selective inflammation-modulatory effects upon diabetogenic cytokine exposure.

cell biology↗

bioRxiv2024

Beta-Cell Pyroptosis - A Burning Flame in Type 1 Diabetes?

Immune-mediated destruction of the beta-cells in the pancreatic islets of Langerhans is the underlying cause of type 1 diabetes (T1D). Despite decades of research, the exact mechanisms involved at the beta-cell level during the development of disease remain poorly understood. This includes the mode(s) of beta-cell death and signaling events implicated in exacerbating local islet inflammation and immune cell infiltration, commonly known as insulitis. In disease models, beta-cell apoptosis seems to be the predominant cell death form which has led to the general assumption that beta cells mostly die by apoptosis in T1D. However, apoptosis is an anti-inflammatory programmed cell death mechanism, and this dogma is therefore challenged by the pathogenetic nature of T1D, as a progressive increase in islet inflammation is seen. This infers that other modes of beta-cell death that inherently increase insulitis may predominate. One such mechanism could be the newly characterized form of programmed cell death; pyroptosis (from the Greek "fire-falling"). Pyroptosis is characterized by gasdermin-mediated cell lysis with a bursting release of pro-inflammatory factors. Beta-cell death by pyroptosis in T1D may therefore offer a plausible explanation for the exacerbated paracrine islet inflammation that spreads during the progression of insulitis. Here, we briefly debate the evidence supporting beta-cell pyroptosis in T1D as a central mechanism of islet inflammation and beta-cell demise. The paper intends to challenge the current understanding of beta-cell destruction to move the field forward. Importantly, we present experimental data from human islets and EndoC-{beta}H5 cells that directly support beta-cell pyroptosis as a rational death mechanism in T1D. We suggest a model of beta-cell demise in T1D in which pyroptosis plays a prominent role in concert with other cell death mechanisms. As the role of pyroptosis in disease is still in its infancy, we hope also to inspire researchers working in other disease fields.

cell biology↗

bioRxiv2022

Characterisation of the functional and transcriptomic effects of pro-inflammatory cytokines on human EndoC- βH5 beta cells

ObjectiveEndoC-{beta}H5 is a newly established human beta-cell model which may be superior to previous models of native human beta cells. Exposure of beta cells to proinflammatory cytokines is a widely used in vitro model of immune-mediated beta-cell failure in type 1 diabetes and we therefore performed an in-depth characterisation of the effects of cytokines on EndoC-{beta}H5 cells. MethodsThe sensitivity profile of EndoC-{beta}H5 cells to the toxic effects of the pro-inflammatory cytokines interleukin-1{beta} (IL-1{beta}), interferon {gamma} (IFN{gamma}) and tumour necrosis factor- (TNF) was examined in titration and time-course experiments. Cell death was evaluated by caspase 3/7 activity, cytotoxicity, viability, TUNEL assay and immunoblotting. Mitochondrial function was evaluated by extracellular flux technology. Activation of signalling pathways and major histocompatibility complex (MHC) class I expression were examined by immunoblotting, immunofluorescence, and real-time quantitative PCR (qPCR). Glucose-stimulated insulin secretion (GSIS) and cytokine-induced chemokine secretion were measured by ELISA and Meso Scale Discovery multiplexing electrochemiluminescence, respectively. Global gene expression was characterised by stranded RNA sequencing. ResultsCytokines increased caspase activity and cytotoxicity in EndoC-{beta}H5 cells in a time- and dose-dependent manner. The proapoptotic effect of cytokines was primarily driven by IFN{gamma}. Cytokine exposure caused impaired mitochondrial function, diminished GSIS, and induced secretion of chemokines. At the signalling level, cytokines increased the phosphorylation of signal transducer and activator of transcription 1 (STAT1) but not c-jun N-terminal kinase (JNK) and did not cause degradation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor (I{kappa}B). MHC class I was induced by cytokines. Cytokine exposure caused significant changes to the EndoC-{beta}H5 transcriptome including upregulation of HLA genes, endoplasmic reticulum stress markers, and non-coding RNAs. Among the differentially expressed genes were several type 1 diabetes risk genes. ConclusionsOur study provides detailed insight into the functional and transcriptomic effects of cytokines on EndoC-{beta}H5 cells. This knowledge will be helpful for future investigations studying cytokine effects in this cell model.

cell biology↗