2. Academic Validation
  3. MTHFD2 promotes osteoclastogenesis and bone loss in rheumatoid arthritis by enhancing CKMT1-mediated oxidative phosphorylation

MTHFD2 promotes osteoclastogenesis and bone loss in rheumatoid arthritis by enhancing CKMT1-mediated oxidative phosphorylation

  • BMC Med. 2025 Feb 27;23(1):124. doi: 10.1186/s12916-025-03945-y.
Yujing Li 1,  Minglong Cai 1,  Yi Qin 1 2,  Xiaojuan Dai 1,  Liyuan Liang 3,  Zhenyu Li 1,  Xi Wen 1,  Huizhi Jin 1,  Chao Yang # 4,  Zhu Chen # 5
Affiliations

Affiliations

  • 1 Department of Rheumatology and Immunology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, China.
  • 2 Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich Alexander University Erlangen-Nuremberg and Universitätsklinikum Erlangen, Erlangen, Germany.
  • 3 The MED-X Institute, Center for Cancer Precision Medicine, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an Jiaotong University, Building 21, Western China Science and Technology Innovation Harbor, Xi'an, 710000, China.
  • 4 Department of Rheumatology and Immunology and The MED-X institute, Center for Immunological and Metabolic Diseases, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an Jiaotong University, Building 21, Western China Science and Technology Innovation Harbor, Xi'an, 710000, China. ychmax@xjtufh.edu.cn.
  • 5 Department of Rheumatology and Immunology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, China. doczchen@ustc.edu.cn.
  • # Contributed equally.
PMID: 40016725 DOI: 10.1186/s12916-025-03945-y
Abstract

Background: Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by disrupted bone homeostasis. This study investigated the effect and underlying mechanisms of one-carbon metabolism Enzyme methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) on osteoclast differentiation and bone loss in RA.

Methods: The expression of MTHFD2 was examined in CD14 + monocytes and murine bone marrow-derived macrophages (BMMs). RNA-sequencing was performed to evaluate the regulatory mechanisms of MTHFD2 on osteoclastogenesis. Extracellular flux assay, JC-1 staining, and transmission electron microscopy were used to detect mitochondrial function and energy metabolism changes during osteoclast formation. Collagen-induced arthritis (CIA) mice were used to evaluate the therapeutic effect of MTHFD2 knockdown on bone loss. Bone volume and osteoclast counts were quantified by μCT and histomorphometry.

Results: Elevated MTHFD2 was observed in RA patients and CIA mice with a positive correlation to bone resorption parameters. During osteoclast formation, MTHFD2 was significantly upregulated in both human CD14 + monocytes and murine BMMs. The application of MTHFD2 inhibitor and MTHFD2 knockdown suppressed osteoclastogenesis, while MTHFD2 overexpression promoted osteoclast differentiation in vitro. RNA-sequencing revealed that MTHFD2 inhibition blocked Oxidative Phosphorylation (OXPHOS) in osteoclasts, leading to decreased adenosine triphosphate (ATP) production and mitochondrial membrane potential without affecting mitochondrial biogenesis. Mechanistically, inhibition of MTHFD2 downregulated the expression of mitochondrial creatine kinase 1 (CKMT1), which in turn affected phosphocreatine energy shuttle and OXPHOS during osteoclastogenesis. Further, a therapeutic strategy to knock down MTHFD2 in knee joint in vivo ameliorated bone loss in CIA mice.

Conclusions: Our findings demonstrate that MTHFD2 is upregulated in RA with relation to joint destruction. MTHFD2 promotes osteoclast differentiation and arthritic bone erosion by enhancing mitochondrial energy metabolism through CKMT1. Thus, targeting MTHFD2 may provide a potential new therapeutic strategy for tackling osteoclastogenesis and bone loss in RA.

Keywords

Methylenetetrahydrofolate dehydrogenase 2; Osteoclast differentiation; Oxidative phosphorylation; Rheumatoid arthritis.

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