Figure 1. L. gasseri expressing PA-DCpep is safe for mice at high doses.
C57BL/6 mice were orally gavaged with 109 CFU of L. gasseri expressing PA-DCpep once and the CFU per gram of feces was determined (A) in MRS plates with erythromycin (5 µg/mL). C57BL/6 mice were orally gavaged with increasing doses of L. gasseri expressing PA-DCpep (107, 109 and 1012 CFU) or PBS, serum was collected after days 1, 3 and 7, and the enzyme activities of ALT/SGPT (B) and AST/SGOT (C) were analyzed by ELISA. CCl4 was used as a positive control for toxicity (B & C). Tissues from C57BL/6 mice orally gavaged with increasing doses of L. gasseri expressing PA-DCpep (107, 109 and 1012 CFU) or PBS were collected and sections stained with H&E at days 1, 3 and 7 of treatment. (D) Photomicrographs of H&E sections of liver A–D, kidney E–H, spleen I–L, colon M–P, and cecum Q–T. Insets of a representative glomerulus and surrounding proximal tubules are included in each of the kidney photomicrographs. Insets of high magnification of the lymphoid tissue are included in each of the spleen photomicrographs. For each of the organs, the PBS control is pictured in the left column A, E, I, M and Q, respectively. The three photomicrographs on the right are from increasing concentrations of bacteria from 107, 109 and 1012 from left to right.