Deficiency of Omentin-1 leads to delayed fracture healing through excessive inflammation and reduced CD31hiEmcnhi vessels

Mol Cell Endocrinol. 2021 Aug 20:534:111373. doi: 10.1016/j.mce.2021.111373. Epub 2021 Jun 23.

Abstract

Fracture healing is a complicated process affected by many factors, such as inflammatory responses and angiogenesis. Omentin-1 is an adipokine with anti-inflammatory properties, but whether omentin-1 affects the fracture healing process is still unknown. Here, by using global omentin-1 knockout (omentin-1-/-) mice, we demonstrated that omentin-1 deficiency resulted in delayed fracture healing in mice, accompanied by increased inflammation and osteoclast formation, and decreased production of platelet-derived growth factor-BB (PDGF-BB) and osteogenesis-promoting vessels that are strongly positive for CD31 and Endomucin (CD31hiEmcnhi) in the fracture area. In vitro, omentin-1 treatment suppressed the ability of the tumor necrosis factor-α (TNF-α)-activated macrophages to stimulate multi-nuclear osteoclast formation, resulting in a significant increase in the generation of mono-nuclear preosteoclasts and PDGF-BB, a pro-angiogenic protein that is abundantly secreted by preosteoclasts. PDGF-BB significantly augmented endothelial cell proliferation, tube formation and migration, whereas direct treatment with omentin-1 did not induce obvious effects on angiogenesis activities of endothelial cells. Our study suggests a positive role of omentin-1 in fracture healing, which may be associated with the inhibition of inflammation and stimulation of preosteoclast PDGF-BB-mediated promotion of CD31hiEmcnhi vessel formation.

Keywords: CD31(hi)Emcn(hi) vessel; Fracture healing; Inflammation; Omentin-1; PDGF-BB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Movement
  • Cytokines / genetics*
  • Disease Models, Animal
  • Female
  • Femoral Fractures / etiology
  • Femoral Fractures / genetics*
  • Femoral Fractures / immunology
  • Fracture Healing*
  • GPI-Linked Proteins / genetics*
  • Gene Knockout Techniques
  • Lectins / genetics*
  • Mice
  • Osteoclasts / metabolism
  • Osteogenesis
  • Platelet Endothelial Cell Adhesion Molecule-1 / metabolism
  • RAW 264.7 Cells
  • Sialoglycoproteins / metabolism*
  • X-Ray Microtomography

Substances

  • Cytokines
  • Emcn protein, mouse
  • GPI-Linked Proteins
  • Itln1 protein, mouse
  • Lectins
  • Pecam1 protein, mouse
  • Platelet Endothelial Cell Adhesion Molecule-1
  • Sialoglycoproteins