2024, Vol. 28 ›› Issue (26): 4178-4183

Deficiency of interleukin-9 inhibits osteogenic potential in mice

Wang Yi, Chen Chichi, Zhou Xichao, Shi Qin   

Abstract: BACKGROUND: Mouse osteogenic potential is regulated by the JAK-STAT signaling pathway, and interleukin-9 can regulate multiple cellular functions through the JAK-STAT pathway, which has the potential to be a novel cytokine that regulates osteogenic potential.
OBJECTIVE: To investigate the effect of interleukin-9 deficiency on osteogenic potential in mice
METHODS: The femurs collected from 2-month-old wild-type and interleukin-9 knockout mice were subjected to Micro-CT scanning to analyze the changes in bone mass. Then, hematoxylin-eosin staining, Masson staining, and immunohistochemical staining of type I collagen were performed on the slices of the femurs of mice. Bone marrow cells from 2-month-old wild-type and interleukin-9 knockout mice were extracted for colony-forming assay and detection of osteogenic gene expression in bone marrow mesenchymal stem cells. To further verify whether interleukin-9 worked through the JAK-STAT pathway, the expression of STAT3 protein was detected by western blot.
RESULTS AND CONCLUSION: Micro-CT results showed the bone mass of interleukin-9 knockout mice decreased significantly compared with that of wild-type mice. In addition, the bone mineral density, bone volume fraction, trabecular number significantly decreased and trabecular separation markedly escalated in interleukin-9 knockout mice. The findings of hematoxylin-eosin staining were consistent with Micro-CT results. Interleukin-9 knockout mice had lower bone trabecular density. Type I collagen immunohistochemistry staining and Masson staining indicated the number of type I collagen positive osteoblasts was significantly reduced and the capacity of collagen formation was damaged in interleukin-9 knockout mice. The results of colony-forming assay indicated that the mineralization capacity of osteoblast in interleukin-9 knockout mice were significantly lower than that in wild-type mice. Western blot results showed that osteogenesis induction activated STAT3 signaling, and the pSTAT3 level in wild-type mice with osteogenic induction was significantly higher than that in interleukin-9 knockout mice with osteogenic induction. These findings suggest that interleukin-9 regulates osteogenesis through the JAK-STAT3 pathway and interleukin-9 deficiency inhibits osteoblast differentiation and function, which may lead to reduced bone mass in interleukin-9 knockout mice.

Key words: interleukin-9, osteoporosis, mesenchymal stem cell, osteogenic capability, osteogenic induction, osteogenic mineralization