Teleost fish skin serves as the first line of defense against pathogens. The interaction between pathogen and host skin determines the infection outcome. However, the mechanism(s) that modulate infection remain largely unknown. A proper tissue culture model that is easier to handle but can quantitatively and qualitatively monitor infection progress may shed some lights. Here, we use striped catfish (Pangasius hypophthalmus) to establish an ex vivo skin explant tissue culture model to explore host pathogen interactions. The skin explant model resembles in vivo skin in tissue morphology, integrity, and immune functionality. Inoculation of aquatic pathogen Aeromonas hydrophila in this model induces epidermal exfoliation along with epithelial cell dissociation and inflammation. We conclude that this ex vivo skin explant model could serve as a teleost skin infection model for monitoring pathogenesis under various infection conditions. The model can also potentially be translated into a platform to study prevention and treatment of aquatic infection on the skin in aquaculture applications.

The fish skin mucosal microbiota is essential in modulating the host response to the presence of pathogens. Our study provides a platform to study both the correlation and causation of the interactions among the pathogen, fish skin, and the skin mucosal microbiota.

Teleost fish skin serves as the first line of defense against pathogens. The interaction between pathogen and host skin determines the infection outcome. However, the interaction and infection mechanisms remain largely unknown due to the lack of a proper tissue model that can quantitatively and qualitatively monitor infection progress. Here, we use striped catfish (Pangasius hypophthalmus) to establish an ex vivo skin explant tissue model that has not been explored in teleost fish before. The skin explant model, cultured by creating epithelial polarity, resembles the in vivo skin in tissue morphology, integrity, and mucous cell and immune functionality. Inoculation of Aeromonas hydrophila in this model induces epidermal exfoliation along with epithelial cell junction disassembly and inflammation. We therefore concluded that this ex vivo skin explant model could serve as a teleost skin infection model for monitoring pathogenesis under various infection conditions. The model can also potentially be translated into a platform to study prevention and treatment for aquatic infection on mucosal surface in aquaculture applications.