Alpha-ketoglutarate accelerates granulocyte-monocyte progenitor differentiation and atherosclerotic plaque inflammation via oxoglutarate receptor 1

Accumulating evidence shows that excess cholesterol and glucose uptake stimulates the expansion of hematopoietic stem/progenitor cells and myeloid progenitors, resulting in increased production of inflammatory cells and atherosclerotic progression. However, the role of other metabolites in plaque progression remains unclear. Hereby, we observed elevated α-ketoglutarate levels in granulocyte-monocyte progenitors (GMPs) of Ldlr^-/- mice on a high-fat diet (HFD), determined by targeted metabolomics. On top of HFD, α-ketoglutarate administration further increased GMP proportion, myeloid cell production, and plaque progression in Ldlr^-/- mice. The regulation of α-ketoglutarate in atherosclerosis required the expression of its receptor, oxoglutarate receptor 1 (OXGR1), in bone marrow cells (BMCs), as transplantation of OXGR1^-/- BMCs attenuated plaque progression compared to transplantation of OXGR1^+/+ BMCs in HFD-fed Ldlr^-/- recipients. Using targeted metabolomics, single-cell RNA sequencing and validation experiments, we demonstrated that the α-ketoglutarate/OXGR1 axis upregulated the expression of purine nucleoside phosphorylase (PNP) in GMPs, which promoted de novo purine biosynthesis and reduced the levels of nicotinamide mononucleotide and nicotinamide adenine dinucleotide (NAD), thereby disturbing mitochondrial homeostasis and increasing the production of myeloid cells. Furthermore, proteomics data revealed that PNP treatment regulated the redox status by increasing the expression of NAD kinase (NADK), thereby accelerating NAD consumption. Additionally, PNP promoted the transcriptional activation of NF-κB via ubiquitin, enhancing ROS production and inflammation in lineage^-/low cells. Spearman's correlation analysis revealed a positive association between isocitrate and low-density lipoprotein cholesterol levels in human plasma. Overall, HFD potentiated α-ketoglutarate, contributing to atherosclerosis.