Lactobacillus plantarum WCFS1 alleviates Aeromonas hydrophila NJ-1-induced inflammation and muscle loss in zebrafish (Danio rerio)

Lactobacillus plantarum is known beneficial for the fish to defend against Aeromonas hydrophila infection which causes major disease outbreaks and severe economic losses for aquaculture. However, the mechanisms remain unclear. In the present study, 240 zebrafish with an average body weights of 0.33 ± 0.01 g were randomly divided into 4 groups. The zebrafish were fed a basal diet supplemented with 3.3 × 108 CFU L. plantarum WCFS1/g or not for 1 week. They were then exposed to water supplementation with or without 1.5 × 108 CFU A. hydrophila NJ-1/mL for 1 day. Finally, all the fish were transferred to fresh water and fed the basal diets for 5 days. The results showed that dietary supplementation with L. plantarum WCFS1 attenuated mortality, A. hydrophila NJ-1 colonization, histological damage, and inflammation in the intestine, liver, gill, and muscle of zebrafish challenged with A. hydrophila NJ-1. In addition, the suppressive effect of L. plantarum WCFS1 on pro-inflammatory genes expression (interleukin 1β and tumor necrosis factor-α) was associated with altered mRNA levels for autophagy (lysosomal-associated membrane protein 1, lysosomal-associated membrane protein 2, autophagy-related gene 6, and autophagy-related gene 5) and hypoxia-inducible factors (hypoxia-inducible factors-1αa, hypoxia-inducible factors-1αb, and hypoxia-inducible factors-3α). Furthermore, L. plantarum WCFS1 alleviated A. hydrophila NJ-1-induced muscle loss by down-regulation of mRNA expression for myostatin and F-box protein 32, and up-regulation of mRNA expression for myogenin and myogenic determination 1. Collectively, L. plantarum WCFS1 holds great potential in aquaculture to defend against A. hydrophila infection.