Morus Alba Stem Extract Suppresses Matrix Metalloproteinases (MMP)-1, MMP-9, and Tissue Inhibitors of Metalloproteinase (TIMP)-1 Expression Via Inhibition of IκBα Degradation Induced by Porphyromonas Gingivalis LPS Signal in THP-1 Cells

Objectives: The aim of this study is to evaluate the inhibitory effects of stem extract (MSE) on the expression of matrix metalloproteinases (MMP)-1, MMP-9, and tissue inhibitors of metalloproteinase (TIMP)-1 in lipopolysaccharide (LPS)-activated-acute monocytic leukemia cell line (THP-1).

Materials And Methods: THP-1 cells were treated with noncytotoxic concentrations of MSE combined with 1 µg/mL of LPS. The mRNA levels of MMP-1, MMP-9, and TIMP-1 were evaluated via quantitative real-time polymerase chain reaction. The secreted proteins in the culture media were detected by enzyme-linked immunosorbent assay. The degradation of inhibitor of kappa B-alpha (IκBα) protein was tracked by Western blotting.

Statistical Analysis: Comparisons in experiments were analyzed with analysis of variance followed by Tukey honestly significant difference comparison test.

Results: Twenty and 40 µg/mL of MSE significantly downregulated MMP-1 and MMP-9 genes and protein expression but upregulated the gene expression of TIMP-1 ( < 0.05). LPS induced degradation of IκBα, while addition of MSE (20 and 40 µg/mL) increased IκBα cytosolic levels. MSE was able to suppress the LPS-induced MMPs expression and also increased the gene expression of TIMP-1 via the inhibition of the cytoplasmic IκBα degradation in THP-1 cells.

Conclusions: The present observations suggest that MSE exerted a positive effect on the regulatory mechanism between MMPs and TIMP, which is an important implication for the therapeutic potential of MSE in periodontitis.