FIG. 2.
Proinflammatory activities of Lactobacillus subcellular fractions. Various subcellular fractions of L. casei were prepared as described in Materials and Methods. (A) RAW264.7 cells (5 × 105/ml) were stimulated with subcellular fractions isolated from L. casei. Each bacterial fraction was added to the culture medium at 1 μg/ml, and the TNF-α concentration in the culture supernatants was measured by ELISA after 12 h of incubation. (B) RAW264.7 cells were plated at 7.5 × 105 cells/plate and on the next day were transiently transfected with 1 μg each of a reporter plasmid containing tandem NF-κB consensus binding sites (pGL3-NF-kB-luc) and pRL-SV40 (as an internal control). At 48 h after the transfection, Lactobacillus subcellular fractions were added at 1 μg/ml, and the cell lysates were collected after 8 h of incubation to measure the relative luciferase activities. The experiment was repeated three times with similar results. A typical result is shown.