M1 macrophage-derived oncostatin M induces osteogenic differentiation of ligamentum flavum cells through the JAK2/STAT3 pathway

Jun Yang; Guanghui Chen; Tianqi Fan; Xiaochen Qu

doi:10.1002/jsp2.1290

M1 macrophage-derived oncostatin M induces osteogenic differentiation of ligamentum flavum cells through the JAK2/STAT3 pathway

JOR Spine. 2023 Oct 18;7(1):e1290. doi: 10.1002/jsp2.1290. eCollection 2024 Mar.

Authors

Jun Yang^{1

2}, Guanghui Chen³, Tianqi Fan³, Xiaochen Qu^{1

2

3}

Affiliations

¹ Department of Orthopaedics First Affiliated Hospital of Dalian Medical University Dalian China.
² Department of Orthopaedics Key Laboratory of Molecular Mechanism for Repair and Remodeling of Orthopaedic Diseases Dalian China.
³ Department of Orthopaedics Peking University Third Hospital Beijing China.

Abstract

Background: M1 macrophages (Mφs) are involved in osteogenic differentiation of ligamentum flavum (LF) cells and play an important role in heterotopic ossification. However, the mechanism by which M1 Mφs influence osteogenic differentiation of LF cells has not been studied.

Methods: The effect of conditioned medium including secretions of M1 Mφs (CM-M1) on LF cells was analyzed by GeneChip profiling and ingenuity pathway analysis (IPA). THP-1 cells were polarized into M1 Mφs and CM-M1 was used to induce LF cells. In addition, LF cells were induced by CM-M1 in the presence of cyclooxygenase 2 (COX-2) inhibitors or oncostatin M (OSM)-neutralizing antibodies. Based on the presence of OSM, knockout of OSMR or GP130 receptors, or addition of the Janus kinase 2 (JAK2) inhibitor AZD1480 or signal transducer and activator of transcription 3 (STAT3) inhibitor Stattic were examined for effects on osteogenic differentiation of LF cells. OSM secretion was quantified by ELISA, while qPCR and western blot were used to evaluate expression of osteogenic genes and receptor and signaling pathway-related proteins, respectively.

Results: GeneChip and IPA results indicate that the OSM signaling pathway and its downstream signaling molecules JAK2 and STAT3 are significantly activated. ELISA results indicate that OSM is highly expressed in cells treated with CM-M1 and lowly expressed in cells treated with CM-M1 and a COX-2 inhibitor. Besides, CM-M1 induces osteogenic differentiation of LF cells, which is weakened when COX-2 inhibitors or OSM-neutralizing antibody are added to it. Recombinant OSM could induce osteogenic differentiation of LF cells and upregulate expression of OSMR, GP130, phosphorylated (P)-JAK2, and P-STAT3. Upon knockdown of OSMR or GP130, or the addition of AZD1480 or Stattic, P-JAK2 and P-STAT3 expression were decreased and osteogenic differentiation was reduced.

Conclusion: M1 Mφ-derived OSM induces osteogenic differentiation of LF cells and the JAK2/STAT3 signaling pathway plays an important role.

Keywords: JAK2/STAT3 signaling; macrophages; oncostatin M; ossification of the ligamentum flavum.