The Role Of Endoplasmic Reticulum Stress In The Secretion Of IL-6Induced By Advanced Glycation End Products In MG63Cells

Objective: Advanced glycation end products (AGEs) have been implicated in theaccelerated osteoporosis occurred in diabetes. Recent studies showed that AGEs wereinvolved in bone formation of osteoblasts and bone resorption of osteoclasts, and thenpromoting osteoporosis. In this study, we examined the role of endoplasmic reticulumstress in the secretion of IL-6induced by advanced glycation end products in MG63cells. These studies will provide further understanding the formation pathogenesis ofdiabetes accelerated osteoporosis.Methods:①MG63cells were incubated in different concentrations of AGEs（0、50、100、200、400μg/ml）for24h, the cells viability was detected by MTT.②The effectof different concentrations of AGEs（0、50、100、200μg/ml）on the expression of IL-6in MG63cells were investigated by ELSIA. To further explore the role of AGEs andassociated signaling pathway in expression of cytokines, MG63cells whichprestimulated by aminoguanidine、tauroursodeoxycholic acid、N-acetyl-L-cysteine、diphenyleneiodonium chloride for1h and then were stimulated with200μg/mlAGEsfor24h, the expression of IL-6was determined by ELSIA.③The effects of differentconcentrations of AGEs（0、50、100、200μg/ml）on the expression of p-IRE/IRE、p-JNK/JNK and GRP78/β-actin in MG63cells were observed by Western blot. MG63cells which incubated with aminoguanidin （AG）、 tauroursodeoxycholic acid(TUDCA)、N-acetyl-L-cysteine (NAC) and diphenyleneiodonium chloride (DPI) for1h and then were stimulated with200μg/ml AGEs for24h, the expression of p-IRE/IRE、p-JNK/JNK and GRP78/β-actin were determined by Western blot.Results:①No changes in cell viability was observed when MG63cells were treatedwith50~200μg/ml AGEs for24h; but400μg/ml AGEs can suppress the growth of MG63cells (P<0.05).②From ELISA, we found a significant increase in IL-6expression in MG63cells exposed to AGEs（50~200μg/ml）compared with controlgroup, and the most significant effect was200μg/mlAGEs group (P<0.01).Furthermore, the AGEs-stimulated IL-6were significantly suppressed by AG、TUDCA、NAC and DPI.③From Western blot, we found a significant increase inp-IRE/IRE、p-JNK/JNK and GRP78/β-actin expression in MG63cells exposed toAGEs（50~200μg/ml）compared with control group, and the most significant effectwas200μg/ml AGEs group (P<0.01). Furthermore, the AGEs-stimulated p-IRE/IRE、p-JNK/JNK and GRP78/β-actin were significantly suppressed by AG、TUDCA、NACand DPI.Conclusion: The findings from this study suggested that AGEs could promote thesecretion of inflammatory cytokines IL-6in MG63cells via endoplasmic reticulumstress signal pathway. The expression of p-IRE/IRE、p-JNK/JNK and GRP78/β-actinwere significantly suppressed by AG、NAC and DPI, indicating that the activation ofendoplasmic reticulum stress is linked with oxidative stress pathways.