Dapagliflozin promotes beta cell regeneration by inducing pancreatic endocrine cell phenotype conversion in type 2 diabetic mice

Abstract

Background: Clinical trials and animal studies have shown that sodium-glucose co-transporter type 2 (SGLT2) inhibitors improve pancreatic beta cell function. Our study aimed to investigate the effect of dapagliflozin on islet morphology and cell phenotype, and explore the origin and possible reason of the regenerated beta cells. Methods: Two diabetic mouse models, db/db mice and pancreatic alpha cell lineage-tracing (glucagon-β-gal) mice whose diabetes was induced by high fat diet combined with streptozotocin, were used. Mice were treated by daily intragastric administration of dapagliflozin (1 mg/kg) or vehicle for 6 weeks. The plasma insulin, glucagon and glucagon-like peptide-1 (GLP-1) were determined by using ELISA. The evaluation of islet morphology and cell phenotype was performed with immunofluorescence. Primary rodent islets and αTC1.9, a mouse alpha cell line, were incubated with dapagliflozin (0.25-25 μmol/L) or vehicle in the presence or absence of GLP-1 receptor antagonist for 24 h in regular or high glucose medium. The expression of specific markers and hormone levels were determined. Results: Treatment with dapagliflozin significantly decreased blood glucose in the two diabetic models and upregulated plasma insulin and GLP-1 levels in db/db mice. The dapagliflozin treatment increased islet and beta cell numbers in the two diabetic mice. The beta cell proliferation as indicated by C-peptide and BrdU doublepositive cells was boosted by dapagliflozin. The alpha to beta cell conversion, as evaluated by glucagon and insulin double-positive cells and confirmed by using alpha cell lineage-tracing, was facilitated by dapagliflozin. After the dapagliflozin treatment, some insulin-positive cells were located in the duct compartment or even colocalized with duct cell markers, suggestive of duct-derived beta cell neogenesis. In cultured primary rodent islets and αTC1.9 cells, dapagliflozin upregulated the expression of pancreatic endocrine progenitor and beta cell specific markers (including Pdx1) under high glucose condition. Moreover, dapagliflozin upregulated the expression of Pcsk1 (which encodes prohormone convertase 1/3, an important enzyme for processing proglucagon to GLP-1), and increased GLP-1 content and secretion in αTC1.9 cells. Importantly, the dapagliflozin-induced upregulation of Pdx1 expression was attenuated by GLP-1 receptor antagonist. Conclusions: Except for glucose-lowering effect, dapagliflozin has extra protective effects on beta cells in type 2 diabetes. Dapagliflozin enhances beta cell self-replication, induces alpha to beta cell conversion, and promotes duct-derived beta cell neogenesis. The promoting effects of dapagliflozin on beta cell regeneration may be partially mediated via GLP-1 secreted from alpha cells.

Early combination therapy of empagliflozin and linagliptin exerts beneficial effects on pancreatic β cells in diabetic db/db mice

“…6 e,h). However, we still cannot deny the involvement of re-differentiation of β-cells, α- to β-cell conversion and the influence of humoral factors as previously reported 42 , 43 . It still needs further investigation to clarify this point.…”

A Brief Review of the Mechanisms of β-Cell Dedifferentiation in Type 2 Diabetes

“…Alloxan and caerulein treatment induced trans-differentiation of α-cells into β-cells, and further induction into δ cells in murine and human T1DM [ 31 ]. In particular, treatment with dapagliflozin, the sodium-glucose co-transporter type 2 (SGLT2) inhibitor, induced α-to-β-cell trans-differentiation and promoted duct-derived β-cell neogenesis partially mediated via glucagon-like peptide-1 (GLP-1) in mice [ 32 ]. Therefore, regeneration of β-cells by inducing trans-differentiation from other cell types is an attractive therapeutic option for both types of diabetes.…”

Emergence of SGLT2 Inhibitors as Powerful Antioxidants in Human Diseases

“…Robust clinical evidence [ 70 , 71 ] on the β-cell protection afforded by SGLT2 inhibitors has been documented, with several relevant mechanisms proposed, including deceleration of β cell death and regeneration of pancreatic islet cells via amelioration of glucotoxicity, lipotoxicity, inflammation, fibrosis, and oxidative damage [ 63 , 72 ]. Furthermore, Wei et al reported that SGLT2 inhibitors induced β-cell self-replication, α-to-β cell conversion, and duct-derived β cell neogenesis in an animal model, partially mediated by the additional promotion of glucagon-like peptide-1 (GLP-1) secretion [ 73 ]. Finally, the attenuative effects of SGLT2 inhibitors on oxidative stress and inflammatory responses are also crucial for restoring insulin sensitivity, as discussed above.…”