# Effect of type I collagen on TLR-3 induced MMP-13 expression in human periodontal ligament fibroblasts

## TL;DR

This study shows how collagen and a TLR3 activator affect wound healing and MMP-13 in periodontal cells.

## Contribution

The novel finding is the synergistic effect of collagen and TLR3 activation on MMP-13 expression and cell migration.

## Key findings

- Type I collagen alone accelerated wound healing in hPDL fibroblasts.
- Combining collagen with poly I:C significantly increased MMP-13 mRNA and protein levels.
- Poly I:C alone reduced cell migration but increased MMP-13 expression.

## Abstract

This study examined the effects of type I collagen, alone and in combination with poly I:C—a toll-like receptor 3 (TLR3) agonist—on matrix metalloproteinase-13 (MMP-13) expression and wound healing in human periodontal ligament (hPDL) fibroblasts.

hPDL fibroblasts were cultured and divided into four treatment groups: control, type I collagen (50 μg/mL), poly I:C (10 μg/mL), and a combination of type I collagen with poly I:C. Cytotoxicity was evaluated using the MTT assay. Cell migration was assessed via scratch assay at 0, 24, and 48 h. MMP-13 expression was quantified at both the mRNA and protein levels by real-time PCR and ELISA, respectively.

After 24 h, the MTT assay indicated that none of the four treatment groups exhibited cytotoxicity toward hPDL fibroblasts. In the scratch assay at 24 and 48 h, type I collagen group demonstrated the fastest wound closure, whereas the poly I:C group showed the slowest migration. Regarding MMP-13 expression, the combination group displayed the highest mRNA levels, while ELISA revealed that both the combination and poly I:C groups had the greatest protein expression relative to the control.

This study provides evidence for an interaction between extracellular matrix signals and innate immune activation. Type I collagen promoted hPDL fibroblast migration, whereas poly I:C—a TLR3 agonist—upregulated MMP-13 expression, with the greatest effect observed in combination with collagen.