Effects Of Different Concentrations Of IL-6 On Osteoblast Differentiation Of C2C12 Cells

PurposesBone remodeling is a continuous process involving bone resorption(osteoclast activity)and bone formation(osteoblast activity).Bone regeneration is always affected by high levels of inflammatory cytokines,including TNF-?,IL-6 and so on.At present,there is no consensus on the function of IL-6 on osteogenesis.It has been reported that IL-6 can promote osteogenic differentiation and fracture healing,inhibit osteogenic differentiation and inhibit fracture healing.To explore the possible mechanism of bidirectional effects of IL-6 on osteoblasts.MethodsIn our study,we cultured C2C12 cells with 200ng/ml BMP-2 to induce them to be osteoblasts.On this basis,TNF-?or IL-6(0.1,1.0,10 and 100 ng/ml,respectively)was added to the medium containing BMP-2(200ng/ml)to culture C2C12 cells.On the 7th day,Alizarin red s staining and ALP staining were used to detect the activity of ALP,the expression of Runx2 m RNA,Collagen1A2 m RNA and osteocalcin.The TNF-? group was used as a reference to determine the effect of IL-6.To determine whether TNF-?or IL-6 can reverse the differentiation of osteoblasts induced by BMP-2.To remove BMP-2 after treatment of cells with BMP-2 for 7 days.At the same time,the TNF-? and IL-6 at the concentration of100 ng/ml were added to the cell culture medium for three days.And then to detect Alizarin red s staining and ALP staining as well as activity of ALP and the expression of Runx2 m RNA.ResultsLow concentration of TNF-?(lower than 1ng/ml)could promote the osteogenic differentiation of C2C12,while high concentration of TNF-?could inhibit the differentiation of osteoblasts.However,in this model,different concentrations of IL-6 can promote the intranuclear transport of stat3,and the expression of stat3 in the nucleus is negativelycorrelated with the level of Runx2.Both inflammatory factors can reverse the differentiation of osteoblasts induced by BMP-2.ConclusionsThe osteogenic differentiation of C2C12 cells was inhibited by IL-6 at different concentrations,which was achieved by promoting the transfer of stat3 to the nucleus.As for the promotive effect of IL-6 on osteoblasts reported in the literature,it can be determined that it has nothing to do with the concentration of IL-6.