HAMSAB diet ameliorates dysfunctional signaling in pancreatic islets in autoimmune diabetes.

An altered gut microbiota is associated with type 1 diabetes (T1D), affecting the production of short-chain fatty acids (SCFA) and glucose homeostasis. We previously demonstrated that enhancing serum acetate and butyrate using a dietary supplement (HAMSAB) improved glycemia in non-obese diabetic (NOD) mice and patients with established T1D. The effects of SCFA on immune-infiltrated islet cells remain to be clarified. Here, we performed single-cell RNA sequencing on islet cells from NOD mice fed an HAMSAB or control diet. HAMSAB induced a regulatory gene expression profile in pancreas-infiltrated immune cells. Moreover, HAMSAB maintained the expression of ß-cell functional genes and decreased cellular stress. HAMSAB-fed mice showed preserved pancreatic endocrine cell identity, evaluated by decreased numbers of poly-hormonal cells. Finally, SCFA increased insulin levels in human ß-like cells and improved transplantation outcome in NOD/SCID mice. Our findings support the use of metabolite-based diet as attractive approach to improve glucose control in T1D.

Nova1 or Bim Deficiency in Pancreatic ß-Cells Does Not Alter Multiple Low-Dose Streptozotocin-Induced Diabetes and Diet-Induced Obesity in Mice.

The loss of functional pancreatic ß-cell mass is an important hallmark of both type 1 and type 2 diabetes. The RNA-binding protein NOVA1 is expressed in human and rodent pancreatic ß-cells. Previous in vitro studies indicated that NOVA1 is necessary for glucose-stimulated insulin secretion and its deficiency-enhanced cytokine-induced apoptosis. Moreover, Bim, a proapoptotic protein, is differentially spliced and potentiates apoptosis in NOVA1-deficient ß-cells in culture. We generated two novel mouse models by Cre-Lox technology lacking Nova1 (ßNova1-/-) or Bim (ßBim-/-) in ß-cells. To test the impact of Nova1 or Bim deletion on ß-cell function, mice were subjected to multiple low-dose streptozotocin (MLD-STZ)-induced diabetes or high-fat diet-induced insulin resistance. ß-cell-specific Nova1 or Bim deficiency failed to affect diabetes development in response to MLD-STZ-induced ß-cell dysfunction and death evidenced by unaltered blood glucose levels and pancreatic insulin content. In addition, body composition, glucose and insulin tolerance test, and pancreatic insulin content were indistinguishable between control and ßNova1-/- or ßBim-/- mice on a high fat diet. Thus, Nova1 or Bim deletion in ß-cells does not impact on glucose homeostasis or diabetes development in mice. Together, these data argue against an in vivo role for the Nova1-Bim axis in ß-cells.

PTPN2 Regulates the Interferon Signaling and Endoplasmic Reticulum Stress Response in Pancreatic ß-Cells in Autoimmune Diabetes.

Type 1 diabetes (T1D) results from autoimmune destruction of ß-cells in the pancreas. Protein tyrosine phosphatases (PTPs) are candidate genes for T1D and play a key role in autoimmune disease development and ß-cell dysfunction. Here, we assessed the global protein and individual PTP profiles in the pancreas from nonobese mice with early-onset diabetes (NOD) mice treated with an anti-CD3 monoclonal antibody and interleukin-1 receptor antagonist. The treatment reversed hyperglycemia, and we observed enhanced expression of PTPN2, a PTP family member and T1D candidate gene, and endoplasmic reticulum (ER) chaperones in the pancreatic islets. To address the functional role of PTPN2 in ß-cells, we generated PTPN2-deficient human stem cell-derived ß-like and EndoC-ßH1 cells. Mechanistically, we demonstrated that PTPN2 inactivation in ß-cells exacerbates type I and type II interferon signaling networks and the potential progression toward autoimmunity. Moreover, we established the capacity of PTPN2 to positively modulate the Ca2+-dependent unfolded protein response and ER stress outcome in ß-cells. Adenovirus-induced overexpression of PTPN2 partially protected from ER stress-induced ß-cell death. Our results postulate PTPN2 as a key protective factor in ß-cells during inflammation and ER stress in autoimmune diabetes.

STAT3 Regulates Mitochondrial Gene Expression in Pancreatic ß-Cells and Its Deficiency Induces Glucose Intolerance in Obesity.

Most obese and insulin-resistant individuals do not develop diabetes. This is the result of the capacity of ß-cells to adapt and produce enough insulin to cover the needs of the organism. The underlying mechanism of ß-cell adaptation in obesity, however, remains unclear. Previous studies have suggested a role for STAT3 in mediating ß-cell development and human glucose homeostasis, but little is known about STAT3 in ß-cells in obesity. We observed enhanced cytoplasmic expression of STAT3 in severely obese subjects with diabetes. To address the functional role of STAT3 in adult ß-cells, we generated mice with tamoxifen-inducible partial or full deletion of STAT3 in ß-cells and fed them a high-fat diet before analysis. Interestingly, ß-cell heterozygous and homozygous STAT3-deficient mice showed glucose intolerance when fed a high-fat diet. Gene expression analysis with RNA sequencing showed that reduced expression of mitochondrial genes in STAT3 knocked down human EndoC-ß1H cells, confirmed in FACS-purified ß-cells from obese STAT3-deficient mice. Moreover, silencing of STAT3 impaired mitochondria activity in EndoC-ß1H cells and human islets, suggesting a mechanism for STAT3-modulated ß-cell function. Our study postulates STAT3 as a novel regulator of ß-cell function in obesity.

Transcriptomics data of a human in vitro model of non-alcoholic steatohepatitis exposed to elafibranor.

The present dataset contains the transcriptomic characterization of a novel in vitro model of non-alcoholic steatohepatitis (NASH) as well as its transcriptomics read-outs for the evaluation of elafibranor, a potential anti-NASH compound. We report whole genome microarray data (Affymetrix HG U133 plus 2.0) of human multipotent stem cell-derived hepatic cells (hSKP-HPC) exposed to mediators of NASH. These cells were exposed to lipogenic inducers (insulin, glucose, fatty acids) and pro-inflammatory factors (IL-1ß, TNF-α, TGF-ß) to trigger hepatocellular responses characteristic of NASH. In addition, to evaluate the anti-NASH features of elafibranor, a dual peroxisome proliferator-activated receptor (PPAR) agonist that currently is under investigation as a potential anti-NASH therapeutic, was tested this in vitro set-up. This paper provides a detailed description of the microarray data as well as an indication of their value for evaluating cell signaling pathways (e.g. NFκB network) during the in vitro evaluation of anti-NASH compounds. Raw microarray data of different testing conditions were deposited as.CEL files in the Gene Expression Omnibus of NCBI with GEO Series accession number GSE126484. Further interpretation and discussion of these data can be found in the corresponding research article (DOI: 10.1016/j.phrs.2019.04.016) Boeckmans et al., 2019.

Elafibranor restricts lipogenic and inflammatory responses in a human skin stem cell-derived model of NASH.

Non-alcoholic steatohepatitis (NASH) is characterized by hepatocellular steatosis with concomitant hepatic inflammation. Despite its pandemic proportions, no anti-NASH drugs have been approved yet. This is partially because drug development is decelerated due to the lack of adequate tools to assess the efficacy of potential new drug candidates. The present study describes the development and application of a new preclinical model for NASH using hepatic cells generated from human skin-derived precursors. Exposure of these cells to lipogenic (insulin, glucose, fatty acids) and pro-inflammatory factors (IL-1ß, TNF-α, TGF-ß) resulted in a characteristic NASH response, as indicated by intracellular lipid accumulation, modulation of NASH-specific gene expression, increased caspase-3/7 activity and the expression and/or secretion of inflammatory markers, including CCL2, CCL5, CCL7, CCL8, CXCL5, CXCL8, IL1a, IL6 and IL11. The human relevance of the proposed NASH model was verified by transcriptomics analyses that revealed commonly modulated genes and the identification of the same gene classes between the in vitro system and patients suffering from NASH. The application potential of this in vitro model was demonstrated by testing elafibranor, a promising anti-NASH compound currently under clinical phase III trial evaluation. Elafibranor attenuated in vitro key features of NASH, and dramatically lowered lipid load as well as the expression and secretion of inflammatory chemokines, which in vivo are responsible for the recruitment of immune cells. This reduction in inflammatory response was NFκB-mediated. In summary, this human-relevant, in vitro system proved to be a sensitive testing tool for the investigation of novel anti-NASH compounds.