S100A9 Increases IL-6 and RANKL Expressions through MAPKs and STAT3 Signaling Pathways in Osteocyte-Like Cells
S100A9 Increases IL-6 and RANKL Expressions through MAPKs and STAT3 Signaling Pathways in Osteocyte-Like Cells
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DOI：
10.1155/2020/7149408
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发表时间：
2020-02
影响因子：
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通讯作者：
Ryosuke Takagi;E. Sakamoto;J. Kido;Y. Inagaki;Yuka Hiroshima;K. Naruishi;H. Yumoto
中科院分区：
文献类型：
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作者：
Ryosuke Takagi;E. Sakamoto;J. Kido;Y. Inagaki;Yuka Hiroshima;K. Naruishi;H. Yumoto
目的钙护蛋白是S100A8和S100A9的异络合物，主要由炎症状态下的中性粒细胞、单核细胞和软骨细胞分泌。钙保护蛋白与RAGE和TLR4结合，诱导各种细胞中促炎趋化因子和细胞因子的表达。牙周炎是一种慢性炎症性疾病，导致牙龈炎症和牙槽骨吸收。牙周炎患者龈沟液钙保护蛋白水平高于健康患者。本研究探讨了S100A8和S100A9对小鼠骨细胞样细胞（MLO-Y4-A2）促炎因子和骨代谢相关因子表达的影响。设计用S100A8和S100A9处理MLO-Y4-A2细胞，采用PCR、Western blotting或ELISA方法分析RAGE、TLR4、RANKL及几种炎症因子的表达。为了研究细胞内信号通路，通过Western blotting检测MAPK和STAT3的磷酸化，并使用化学特异性抑制剂和sirna。结果S100A9能提高IL-6和RANKL的表达，而S100A8则不能。而S100A8和S100A9均未改变IL-1β、IL-8和TNF-α的表达。虽然S100A9处理没有上调RAGE和TLR4的表达，但转染RAGE和TLR4的siRNA可显著降低IL-6和RANKL的表达。此外，S100A9激活p38、ERK和STAT3信号通路，这些因子的抑制剂显著降低S100A9诱导的IL-6和RANKL的表达。结论S100A9通过与骨细胞RAGE和TLR4信号通路结合诱导IL-6和RANKL的产生，提示S100A9可能在牙周牙槽骨破坏中发挥重要作用。
Objective Calprotectin is a heterocomplex of S100A8 and S100A9 and is mainly secreted from neutrophils, monocytes, and chondrocytes in inflammatory condition. Calprotectin binds to RAGE and TLR4 and induces the expression of proinflammatory chemokines and cytokines in various cells. Periodontitis is a chronic inflammatory disease that leads to gingival inflammation and alveolar bone resorption. Calprotectin levels in gingival crevicular fluid of periodontitis patients are higher than healthy patients. In the present study, the effects of S100A8 and S100A9 on the expressions of proinflammatory cytokines and bone metabolism-related factors in mouse osteocyte-like cells (MLO-Y4-A2) were investigated. Design MLO-Y4-A2 cells were treated with S100A8 and S100A9, and the expressions of RAGE, TLR4, RANKL, and several inflammatory cytokines were analyzed by PCR and Western blotting or ELISA methods. To investigate the intracellular signaling pathways, phosphorylation of MAPK and STAT3 was determined by Western blotting, and chemical specific inhibitors and siRNAs were used. Results Expressions of IL-6 and RANKL were increased by treatment with S100A9 but not S100A8. However, both S100A8 and S100A9 did not change expression of IL-1β, IL-8, and TNF-α. Although RAGE and TLR4 expressions were not upregulated by S100A9 treatment, transfection of siRNA for RAGE and TLR4 significantly decreased IL-6 and RANKL expressions. In addition, S100A9 activated p38, ERK, and STAT3 signaling pathways, and inhibitors for these factors significantly decreased S100A9-induced IL-6 and RANKL expressions. Conclusions These results indicated that S100A9 induces IL-6 and RANKL production via engagement with RAGE and TLR4 signalings in osteocytes and suggested that S100A9 may play important roles in the periodontal alveolar bone destruction.