Figure 7. P. gingivalis modulates oral epithelial antimicrobial cell responses through PLA₂-IIA.

OKF6 cells (1×10⁶) were exposed or not to P. gingivalis [1:50] for 48h and cell lysates obtained with 0.1% Triton in water, in presence of protease inhibitors (PI). Further 40 μl of either OKF6 cell lysates [1 μg/μl total protein] or 10 μg/ml of rPLA2-IIA resuspended in CaCl₂ buffer were pre-incubated with either 30μg/ml of anti-PLA2-IIA antibody or its corresponding isotype control (I. Ctrl.) for 30 minutes on ice before testing their anti-microbial activity against L. monocytogenes (Lm). Lm (10⁶ in 90 μl broth) was incubated with 10 μl of OKF6 cell lysates or rPLA2-IIA after different treatments for 2h. Lm CaCl₂ buffer (vehicle for rPLA2-IIA) incubated only with media, and Triton + PI (OKF6 cell lysis buffer) were used as controls. Further 25μl of Lm (1:1000 dilution) were seeded on blood agar plates and colony forming units (CFUs) quantified after 24h. The mean ± SD of triplicates from each treatment group from a representative experiment of 2 independent experiments are shown. *p≤0.01, ** p≤0.05 denotes significant reduction in CFUs/ml when different treatments were compared with bacterial growth only with media.