1720-P: Single Nucleus Transcriptome Profiling of Human Islet Cells under Metabolic Stress In Vivo

Obesity causes metabolic stress and alterations in the growth and function of islet cells. However, single-cell transcriptome analysis of human islet cells in vivo under the pressure of obesogenic diets and metabolic stress has not been described. Here, we have analyzed the transcriptome profile of human islet grafts transplanted into Rag1-/- immunodeficient mice fed with high fat diet (HFD) using single nucleus RNA sequencing. We have also analyzed activated pathways by gene set enrichment analysis (GSEA) and ligand-receptor interactions by CellChat in the human islet grafts. Diabetic mice were transplanted with 1300 human islets under the kidney capsule. After returning to euglycemia (2 weeks post-transplant), mice were fed with regular diet (RD) or HFD for 4 weeks. A total of 8 human islet grafts (4 pairs of mice, 4 different adult nondiabetic human islet preparations) comprising 45,691 cells were analyzed. HFD-fed mice displayed hyperglycemia, hyperinsulinemia, glucose intolerance and increased human β-cell volume in the islet grafts. Human β-cells showed upregulation of INS, key identity genes (FXYD2, IAPP) and insulin secretion-related genes (SCG3, CHRM3), and downregulation of MAFA and cell integrity-related genes (LRP1B, CDH20, NLGN4Y). Pathway analysis showed enhanced enrichment of the acetylcholine-insulin secretion pathway while decreased enrichment of the endocrine progenitor cell pathway. Ligand-receptor interaction analysis unveiled enhanced communication between α- and β-cells, particularly in molecules involved in inflammation (CD99-CD99), cell adhesion (JAM3-F11R), growth (NRG3-ERBB4) and neuronal communication (NRG1-ERBB4, NCAM1-NCAM1). Our study provides the first single nucleus transcriptome profile of human islet cells in vivo under short-term metabolic stress. It highlights alterations in genes involved in cell integrity, inulin secretion and endocrine progenitor pathways and in ligand-receptor interactions between α- and β-cells.