The Effect of Protocatechuic Acid on LPS Induced Inflammatory Injury in Periodontal Ligament Stem Cells by Regulating the MEK/ERK Signaling Pathway
LI Suxia, YU Yifeng, YUAN Fang*
This study was to explore the effect of PCA (protocatechuic acid) on LPS induced inflammatory injury in PDLSCs (periodontal ligament stem cells) by regulating the MEK (mitogen-activated protein kinase kinase)/ERK (extracellular signal-regulated kinase) signaling pathway. In this study, PDLSCs were divided into the control group, LPS (1.0 μg/mL) group, LPS+5 μmol/L PCA group, LPS+10 μmol/L PCA group, and LPS+10 μmol/L PCA+U0126 (20 μmol/L MEK inhibitor U0126) group. After 24 h, cell proliferation was detected by the CCK-8 method; levels of inflammatory factors (IL-1β, IL-6, and TNF-α) were measured using ELISA kits; apoptosis was detected by flow cytometry. PDLSCs from each group were incubated in osteogenic induction medium, subsequently, alizarin red staining was used to detect mineralized nodules; the content was measured by ALP kit; the expression levels of osteogenic factors and inflammatory factors were detected by qRT-PCR; and the expression levels of proteins related to the MEK/ERK pathway were detected by Western blot. The experimental results showed that, compared with the control group, the LPS group showed a decrease in D450, ALP, staining intensity/D562, RUNX2 (runt related transcription factor 2) mRNA and protein, OCN (osteocalcin) mRNA and protein, MEK, and p-ERK/ERK expression, and an increase in apoptosis rate, IL-1β, IL-6, and TNF-α levels and mRNA expression (P<0.05). Compared with the LPS group, the LPS+5 μmol/L PCA group and LPS+10 μmol/L PCA group showed an increase in D450, ALP, staining intensity/D562, RUNX2 mRNA and protein, OCN mRNA and protein, MEK, and p-ERK/ERK expression, and a de-crease in apoptosis rate, IL-1β, IL-6, and TNF-α levels and mRNA expression, with prominent differences between the groups (P<0.05). Compared with the LPS+10 μmol/L PCA group, the LPS+10 μmol/L PCA+inhibitor group showed a decrease in D450, ALP, staining intensity/D562, RUNX2 mRNA and protein, OCN mRNA and protein, MEK, and p- ERK/ERK expression, and an increase in apoptosis rate, IL-1β, IL-6, and TNF-α levels and mRNA expression (P<0.05). PCA activates the MEK/ERK signaling pathway to alleviate LPS induced inflammatory injury in PDLSCs.
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