Figure 6. Inhibition of DNA methyltransferases using epigallocatechin gallate (EGCG) mediate a decrease in MMP-2 activation, an increase in TIMP-2 transcription and minimal decrease in fibronectin fragmentation in Td-challenged PDL cells.

Cultured PDL cells were pre-treated with 5 or 10 μM EGCG for two days before being challenged with T. denticola (Td) at MOI = 100 or media control for two hours, then incubated for three days. The conditioned medium and cell lysates were collected for zymography, western blotting, and qRT-PCR. The experiments were repeated three times in triplicate. Data were analyzed using one-way ANOVA. (*) represents p ≤ 0.05 compared to the “0” concentration in the same group. (#) represents p ≤ 0.001 compared to the “0” concentration in the same group.

Panel A: Densitometric analysis of pro-MMP-2 (72kDa) and active MMP-2 (64kDa) detected by gelatin zymography. The left 3 lanes represent the control group (unchallenged PDL cells) and the right 3 lanes represent the Td group (Td-challenged PDL cells). The cells in both groups were treated with indicated concentrations of EGCG. The X-axis represents different concentrations of EGCG in the control and Td groups. The Y-axis represents fold-gelatinolytic activity of pro-MMP-2 and active MMP-2 relative to unchallenged and untreated controls.

Panel B: A representative immunoblot of PDL cell culture supernatants probed with a polyclonal anti-fibronectin antibody showing FN fragmentation in conditioned medium from Td-challenged PDL cells, control and EGCG-treated.

Panel C: Bar chart showing transcript levels of MMP-2, MT1-MMP and TIMP-2 in the control and ECGC-treated PDL cells as determined by qRT-PCR. The Y-axis represents fold-expression level of each gene relative to unchallenged and untreated controls. The X-axis represents different concentrations of ECGC in the control and Td groups.