Aim
To determine whether chemokines such as SDF‐1 and monocyte chemoattractant protein‐1 (MCP‐1) are responsible for hydrogen peroxide (H2O2)‐induced extracellular matrix (ECM) degradation and to identify the underlying mechanism in human dental pulp cells (HDPCs).
Method
Human dental pulp cells were exposed to 0.4 mmol H2O2 for 48 h. mRNA expression and protein expression were examined by RT‐PCR and Western blot analysis, respectively. The mRNA expression of chemokine (SDF‐1 and MCP‐1), their receptors (CXCR4 and CXCR2) and extracellular matrix proteins was evaluated by reverse transcriptase‐polymerase chain reaction. The production of SDF‐1, MCP‐1, CXCR4 and CCR2 in the culture medium was determined by enzyme‐linked immunosorbent assay. Signal transduction pathway was examined by Western blotting.
Results
Hydrogen peroxide provoked the activation of MCP‐1 and SDF‐1 mRNA and their respective receptors, CXCR4 and CXCR2. H2O2treatment concomitantly downregulated the expression of ECM molecules, such as type I collagen, elastin and fibronectin, and upregulated the mRNA expression of matrix metalloproteinase‐1 (MMP‐1), MMP‐2, MMP‐8 and MMP‐9. Hydrogen peroxide‐induced ECM degradation and MMP upregulation were blocked by neutralizing antibodies and siRNAs directed against SDF‐1 and MCP‐1. Inhibition of SDF‐1 and MCP‐1 blocked the H2O2‐induced activation of Akt, p38, ERK and NF‐kB.
Conclusion
Inhibition of SDF and MCP‐1 is a potent component of reducing release reactive oxygen species‐induced ECM degradation in HDPCs and may play an important role in pulpal and periapical inflammation.