CMPK2 controls metabolic adaptation and GDF15 induction in inflammatory macrophages 2300489

Abstract

Abstract Introduction CMPK2 is a mitochondrial monophosphate nucleotide kinase robustly induced during inflammatory macrophage activation, increasing the production of both mtDNA and the nucleotide analog ddhCTP, which activate NLRP3 and cGAS/STING pathways and act as anti-viral molecules, respectively. However, its role in macrophage immunometabolism is not well defined. Here, we studied how CMPK2 influences macrophage metabolic rewiring and inflammatory programs. Methods Bone marrow-derived and peritoneal macrophages from WT and myeloid-specific CMPK2 knockout (KO) mice were treated with LPS, LPS+IFNg, and IL-4 for 24 hours. GDF15 expression and release were assessed by RNA sequencing, qPCR, WB, and ELISA. ATP production, OCR, and ECAR were measured by Cell-Titer Glow and Seahorse bioanalyzer, and the ETC complex abundances by WB. Glycolytic and TCA cycle metabolites were measured by 1H-NMR and GC/MS. Human osteoarthritis (OA) synovium from total knee arthroplasty patients was analysed for CMPK2, GDF15, and macrophage markers (CD68, TREM2, CD206) by IHC. Results CMPK2 KO macrophages showed impaired bioenergetics, including reduced total ATP, diminished glycolytic- and OxPhos-derived ATP, and marked lower basal, maximal, and spare respiratory capacity. CMPK2 deficiency also reduced ETC Complex I and III and decreased pyruvate, lactate, and multiple TCA cycle intermediates, including succinate, fumarate, and itaconate. This was accompanied by reduced GDF15 mRNA, protein, and release in inflammatory macrophages and LPS-challenged mice. Synovial CD68+TREM2+ macrophages located in the inflamed synovial lining in human OA synovium highly expressed CMPK2 and GDF15. Conclusion CMPK2 is required for the metabolic and bioenergetic programs that sustain inflammatory macrophage activation and GDF15 induction, and emerges as a potential therapeutic target for inflammatory diseases, modulating inflammatory metabolism and GDF15-driven pathways. Funding Source Health Science Research Grant, UC San Diego Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)