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

Abstract

BackgroundM1 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.MethodsThe 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.ResultsGeneChip 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.ConclusionM1 Mφ‐derived OSM induces osteogenic differentiation of LF cells and the JAK2/STAT3 signaling pathway plays an important role.

Oncostatin M promotes osteogenic differentiation of tendon-derived stem cells through the JAK2/STAT3 signalling pathway

“…found that OSM secreted by macrophages binds to the GP130/OSMR receptor complex, which activates JAK1/2 and mediates phosphorylation of STAT3 to promote osteogenic differentiation of MSCs, and that JAK1/2 inhibitors weaken osteogenic differentiation. Additionally, Yang et al [ 13 ]. found that JAK2/STAT3 inhibitors significantly reduce the incidence of heterotopic ossification during OSM-induced differentiation of ligamentum flavum cells to osteoblasts in vitro.…”

“…The inflammatory environment also has an important role in osteogenic differentiation, and macrophages are critical regulators of inflammation. Under non-coculture conditions, macrophage-associated inflammatory factors TNF-α, IL-6, IL-1β, and OSM are involved in the regulation of osteogenic differentiation with OSM promoting osteogenic differentiation more significantly [ 12 , 13 ]. Although some studies have reported on OSM in osteogenic differentiation, the role of OSM and JAK/STAT signalling in osteogenic differentiation of TDSCs remains unclear.…”

Revealing the novel metabolism‐related genes in the ossification of the ligamentum flavum based on whole transcriptomic data

“…Cell culture was conducted in accordance with the protocol as described in our previous study. 8 Briefly, the collected LF samples were minced into around 0.5 mm 3 pieces, and digested with 250 U/mL type I collagenase (Sigma‐Aldrich, USA) at 37°C for 6 h. The specimen was cultured in Dulbecco's Modified Eagle's medium (Gibco, USA) containing 10% foetal bovine serum (Gibco, USA), 100 U/mL penicillin and 100 μg/mL streptomycin at 37°C with 5% CO 2 . Cells from the two to third passages were used for the further cell experiments.…”

“…OLF is a complex and multifactor disease, and several genetic and environmental factors are involved in the disease susceptibility, including genetic genes, 7 inflammation, 8 mechanical stress, 9 and metabolic disorder. 10 Metabolic disorder could lead to or aggravate multiple human diseases, such as cancers, 11 diabetes, 12 and immunological diseases.…”