Raphael R. Fagundes¹*, Iris Breedijk¹, Amadeo Muñoz Garcia², Françoise Carlotti², Arnaud Zaldumbide¹

¹Dept. of Cell & Chemical Biology, Leiden University Medical Center; ²Dept. of Internal Medicine, Leiden University Medical Center. *r.fagundes_rosa@lumc.nl

Background: Recent evidence highlights the role of cellular stress in β-cells in provoking autoimmune reactivity in type-1 diabetes (T1D). Dysregulation of glycolysis and mitochondrial oxidative phosphorylation in β-cells are key features in several disease models of T1D. The transcriptional factor hypoxia-inducible factor-1 (HIF-1) is a master regulator of cellular metabolism. Its adaptive activation is involved in the development of human T1D and also plays a protective role in disease models. We hypothesize that activation of the HIF-1 pathway protects β-cells against metabolic stress-induced mitochondrial dysfunction.

Methods: Human primary pancreatic islets were exposed to hypoxia or metabolic stressors (high glucose and palmitate) and analysed using scRNAseq. EndoC-βH1 cells were treated with Roxadustat, a HIF-activiting drug, and metabolic stressors for 48 hours.

Results: scRNAseq analysis revealed activation of HIF-1 activation markers in primary β-cells (VEGFA, PFKP, PGK1, ENO1, ENO2 and BNIP3), as well as increased glycolysis (GO:0061621; P=4,4ｘ10^-5) and downregulated oxidative phosphorylation (GO:0006119; P=5,3ｘ10^-6). On the other hand, β-cells in islets treated with metabolic stressors presented upregulation of aerobic respiration (GO:0009060; P= 1,5ｘ10^-5), endoplasmic reticulum stress (GO:0034976; P= 1,9ｘ10^-11), and unfolded protein response (GO:0006986; P= 5,3ｘ10^-10). This stress signature was absent in other endocrine cells in the islets, suggesting the induction of a β-cell specific injury in metabolic stress conditions. Roxadustat treatment upregulated the expression of the glycolytic genes LDHA (6-fold; P < 0,05) and SLC2A1 (1,6-fold; P < 0,05) in EndoC-βH1 cells, and metabolic activity of Roxadustat-treated cells was increased 3-fold even in metabolic stress conditions, compared to control.

Conclusion: We provided first evidence that activation of HIF-1 in pancreatic insulin-producing β-cells skewed cellular metabolism away from error-prone oxidative phosphorylation to glycolysis, harnessing a cytoprotective effect against metabolic stress. In conclusion, by facilitating a shift towards glycolysis, pharmacological HIF-1 activation holds promise for safeguarding pancreatic β-cells against metabolic stress during the early stages of T1D.