Purpose: In the present study, inflammatory responses against five E. coli bacteriophages in rats was investigated.
Methods: Ten rats were orally fed with 8 log PFU/ml of the bacteriophage cocktail per day for periods of up to 4 weeks and sacrificed.
Results: Bacteriophage killing specific bacteria has received interest in applying sanitizers or phage therapy, however, its safety has been in doubt. This study investigated the safety of bacteriophage by determining inflammatory immune response of rats treated with bacteriophage. The rats were administrated with the bacteriophage cocktail of log 8 PFU for E. coli a day for four weeks. Feed consumption and efficiency and body weight were measured and there were no significant differences compared to the control group, and the phage was not detected in the serum collected before autopsy. For the histopathological examination, the notable changes were not observed in tissue of liver, kidney, and spleen. However, measure of organ weight showed some differences from the liver of males and the ovary (left) of females. The remarkable changes were not observed at 12 different cytokines in the serums of the rats. Among mRNA expression of proinflammatory cytokines of COX-2, IL-6, and TNF-α in the liver, kidney, and spleen, COX-2 mRNA expression was increased 2.4-fold, which was a significant difference only in spleen. Therefore, this study showed that there were slight changes in the proinflammatory response of rats fed with the bacteriophage.
Significance: Therefore, the E. coli bacteriophages may potentially induce inflammatory responses in rats.