Advanced glycation end products increase expression of S100A8 and A9 via RAGE-MAPK in rat dental pulp cells.

Advanced glycation end products (AGE) are involved in the progression of diabetic complications. Although our previous reports show that AGE increased dental pulp calcification, AGE accumulation is also associated with inflammation. This study examined AGE effect on the expression of inflammation factors using rat dental pulp tissues and cell cultures. Receptor for AGE (RAGE), S100A8, S100A9, and interleukin (IL)-1β were selected as inflammation parameters. Rat dental pulp cells were cultured and treated with AGE, and the effects were determined by real-time PCR. An anti-RAGE antibody or MAPK pathway inhibitors (PD98059, SB203580, and SP60012) were used to investigate AGE signaling pathway. The mRNA levels of RAGE, S100A8, S100A9, and IL-1β were higher in diabetic pulp tissues. AGE increased mRNA expressions of S100A8, S100A9, and IL-1β in cultured dental pulp cells. In the presence of anti-RAGE antibody, AGE did not increase in S100A8 or S100A9 expressions. The AGE-induced increases in S100A8 and S100A9 were inhibited by PD98059 and SB203580, respectively. Advanced glycation end products increased mRNA expression of S100A8, S100A9, and IL-1β under diabetic pulp conditions, and AGE-induced increases in S100A8 and S100A9 expressions may be associated with the RAGE-MAPK signaling pathway.

Nakajima Y ，Inagaki Y ，Kido J ，Nagata T ... -  《-》

Advanced glycation end-products and Porphyromonas gingivalis lipopolysaccharide increase calprotectin expression in human gingival epithelial cells.

Accumulation of advanced glycation end-products (AGEs) in periodontal tissues of patients with diabetes mellitus aggravates periodontitis, but the mechanisms are unknown. Calprotectin, a heterocomplex of S100A8 and S100A9 proteins, is a constitutive cytoplasmic component of healthy gingival epithelial cells. This study aimed at investigating the effects of AGE and Porphyromonas gingivalis lipopolysaccharide (PgLPS) on calprotectin expression in the human gingival epithelial cell line OBA-9. AGE and PgLPS increased the expression of S100A8 and S100A9 mRNAs, and AGE+PgLPS co-stimulation amplified their expression in OBA-9 cells. A higher concentration of calprotectin in cell lysates was also induced by stimulation with AGE and/or PgLPS. S100A8 was mainly translocated from the nucleus to the cytoplasm by AGE stimulation, while cytoplasmic localization of S100A9 was not altered following stimulation with AGE and/or PgLPS. Calprotectin was found in the cytoplasm of BSA-treated cells, but cytoplasmic and nuclear localization was observed following stimulation with AGE and/or PgLPS. AGE-induced S100A8, and S100A9 mRNA expression was partially suppressed by RAGE-specific siRNA. In contrast, PgLPS-induced S100A8 and S100A9 mRNA expression was strongly suppressed by TLR2-specific siRNA. Furthermore, the inhibition of p38, JNK MAPK, and NF-κB attenuated AGE- and PgLPS-induced S100A8 and S100A9 mRNA expression. Taken together, these results demonstrate that AGE acts in synergy with PgLPS to stimulate RAGE and TLR2 expression and activate p38, JNK MAPK, and NF-κB signaling pathways, resulting in increased activation of calprotectin (S100A8/S100A9) in human gingival epithelial cells. Our results suggest that calprotectin may be involved in the pathogenesis of diabetic periodontitis.

Hiroshima Y ，Sakamoto E ，Yoshida K ，Abe K ，Naruishi K ，Yamamoto T ，Shinohara Y ，Kido JI ，Geczy CL ... -  《-》

RAGE-dependent regulation of calcium-binding proteins S100A8 and S100A9 in human THP-1.

Proinflammatory cell activation via the receptor for advanced glycation end products (RAGE) pathway may play a central pathogenetic role in atherosclerosis. Since S100A8/A9 was recently identified as ligand of RAGE, we determined the effects of proinflammatory cytokines on RAGE-mediated induction of gene expression of S100A8 and S100A9. mRNA levels of S100A8 and S100A9 were upregulated following cytokine stimulation with IL-6 (1, 10, 100 ng/ml) or TNFα (10 ng/ml) in human THP-1 cells. Preincubation of cells with 2000 ng/ml AGE (advanced glycation end products) before cytokine stimulation resulted in upregulation of RAGE. Pretreatment of THP-1 with AGE followed by stimulation with IL-6 (10 ng/ml) or TNFα (10 ng/ml) further increased S100A8 and S100A9 mRNA expression and S100A8/A9 release into cell culture supernatant, as compared to pretreatment with non-glycated albumin as control. Binding of AGE to RAGE was blocked with a neutralizing anti-RAGE antibody. Normal mouse IgG served as control. Cytokine-stimulated induction of S100A8 and S100A9 mRNA levels as well as of S100A8/A9 release after preincubation of cells with AGE were significantly suppressed by RAGE blockade, indicating a RAGE-dependent pathway of AGE-mediated S100A8/A9 expression.The cytokine-induced potentiated S100A8 and S100A9 expression under conditions with a high AGE burden is able to aggravate proinflammatory conditions via activation of the RAGE pathway.

Eggers K ，Sikora K ，Lorenz M ，Taubert T ，Moobed M ，Baumann G ，Stangl K ，Stangl V ... -  《-》

TLR4 and RAGE conversely mediate pro-inflammatory S100A8/9-mediated inhibition of proliferation-linked signaling in myeloproliferative neoplasms.

Kovačić M ，Mitrović-Ajtić O ，Beleslin-Čokić B ，Djikić D ，Subotički T ，Diklić M ，Leković D ，Gotić M ，Mossuz P ，Čokić VP ... -  《-》

Proinflammatory effects of S100A8/A9 via TLR4 and RAGE signaling pathways in BV-2 microglial cells.

Ma L ，Sun P ，Zhang JC ，Zhang Q ，Yao SL ... -  《-》