Figure 4.

Inhibition of microbial infection by pretreatment with vitamin D and butyrate. (A,B) Bacterial infection. OKF6/TERT-1 cells were incubated for 24 h with 100 nm Vitamin D₃, 2 mm Sodium butyrate (NaB), or a combination of 2 mm sodium butyrate and 100 nm Vitamin D₃. After 24 h, cells were infected with either P. gingivalis (A) or F. alocis (B) at an MOI of 500:1 or 200:1, respectively. Bacteria were detected by fluorescent microscopy using 400 µg/ml CFSE and % infected was calculated. (C) Intracellular vs. extracellular killing. OKF6/TERT-1 cells were incubated for 24 h with 100 nm 1,25(OH)₂D₃, 2 mm NaB, or a combination of butyrate and 1,25(OH)₂D₃. Medium was removed, cells were washed once, and infected with P. gingivalis at an MOI of 500:1. Intracellular bacteria were quantified after 2 h. (D) Viral infection. OKF6/TERT-1 cells were incubated for 24 h with 100 nm Vitamin D₃, 2 mm Sodium butyrate (NaB), or a combination of 2 mm sodium butyrate and Vitamin D₃. After 24 h, cells were infected with HSV-1 at an MOI of 0.1:1. After 24 h, total DNA was isolated and relative HSV-1 DNA levels were quantified by QPCR normalized to genomic β-actin DNA. Data are shown as mean (n = 3) ±SD. *p < 0.05; **p < 0.005, by t-test.