In Vivo Effects of Pichia Pastoris-Expressed Antimicrobial Peptide Hepcidin on the Community Composition and Metabolism Gut Microbiota of Rats

Hepcidin, one kind of antimicrobial peptides, is one of the promising alternatives to antibiotics with broad spectrum of antimicrobial activity. Hepcidins cloned from different kinds of fishes have been produced using exogenous expression systems, and their in vitro antimicrobial effects have been verified. However their in vivo effects on gut microbiota and gut health of hosts remain unclear. Here we performed a safety study of hepcidin so that it can be used to reduce microbial contaminations in the food and feed. In this study, Pichia pastoris-expressed Pseudosciaena crocea hepcidin (PC-hepc) was first assessed by simulated digestion tests and then administered to male and female Sprague-Dawley (SD) rats in different concentrations. Subchronic toxicity testing, high throughput 16S rRNA sequencing of gut microbiota, and examinations on gut metabolism and permeability were conducted. The results showed PC-hepc could be digested in simulated intestinal fluid but not in simulated gastric fluid. PC-hepc had no adverse effects on general health, except causing increase of blood glucose (still in the normal value range of this index) in all trial groups of female rats and intestinal inflammation in HD group of female rats. Community composition of gut microbiota of female MD and HD groups shifted compared with control group, of which the decrease of genus Akkermansia might be related to the increase of blood glucose and intestinal inflammation. Significant increase of fecal nitroreductase activity was also observed in female MD and HD groups. Our results suggest the uses of exogenous PC-hepc in normal dosage are safe, however excess dosage of it may cause intestinal disorder of animals.