J Vet Sci.  2024 Jul;25(4):e49. 10.4142/jvs.24076.

NOX4 and its association with Anatomy/Histology/ Embryology myeloperoxidase and osteopontin in regulating endochondral ossification

• Ko K
• Choi S
• Jo M
• Kim C
• Boonpraman N
• Youm J
• Yi SS

• KMID: 2558445
• DOI: http://doi.org/10.4142/jvs.24076

Abstract

Importance
Endochondral ossification plays an important role in skeletal development. Recent studies have suggested a link between increased intracellular reactive oxygen species (ROS) and skeletal disorders. Moreover, previous studies have revealed that increasing the levels of myeloperoxidase (MPO) and osteopontin (OPN) while inhibiting NADPH oxidase 4 (NOX4) can enhance bone growth. This investigation provides further evidence by showing a direct link between NOX4 and MPO, OPN in bone function.
Objective
This study investigates NOX4, an enzyme producing hydrogen peroxide, in endochondral ossification and bone remodeling. NOX4’s role in osteoblast formation and osteogenic signaling pathways is explored.
Methods
Using NOX4-deficient (NOX4^−/− ) and ovariectomized (OVX) mice, we identify NOX4’s potential mediators in bone maturation.
Results
NOX4^−/− mice displayed significant differences in bone mass and structure. Compared to the normal Control and OVX groups. Hematoxylin and eosin staining showed NOX4^−/− mice had the highest trabecular bone volume, while OVX had the lowest. Proteomic analysis revealed significantly elevated MPO and OPN levels in bone marrow-derived cells in NOX4^−/− mice. Immunohistochemistry confirmed increased MPO, OPN, and collagen II (COLII) near the epiphyseal plate. Collagen and chondrogenesis analysis supported enhanced bone development in NOX4^−/− mice.
Conclusions and Relevance
Our results emphasize NOX4’s significance in bone morphology, mesenchymal stem cell proteomics, immunohistochemistry, collagen levels, and chondrogenesis. NOX4 deficiency enhances bone development and endochondral ossification, potentially through increased MPO, OPN, and COLII expression. These findings suggest therapeutic implications for skeletal disorders.

Keyword

Endochondral ossification; myeloperoxidase; NADPH oxidase 4; osteopontin; ovariectomy