Impact of molecular hydrogen treatments on the innate immune activity and survival of zebrafish (Danio rerio) challenged with Aeromonas hydrophila.

Abstract

This study examined the effects of hydrogen-rich water (HRW) immersion on zebrafish (Danio rerio) challenged with the pathogenic bacterium Aeromonas hydrophila. Fish subjected to HRW immersion showed improved post-infection survival rates compared to controls, and bacterial proliferation within the host was markedly reduced. Gene expression analysis in the spleen, kidney, and liver revealed downregulation of pro-inflammatory mediators including IL-1β, IL-6, and NF-κB, alongside upregulation of the anti-inflammatory cytokine IL-10. These findings represent the first investigation of HRW effects in bacterially infected fish and suggest potential applications of molecular hydrogen in aquaculture disease management.

Mechanism

HRW suppresses pro-inflammatory gene expression (NF-κB, IL-1β, IL-6) while upregulating the anti-inflammatory cytokine IL-10 in multiple organs, thereby modulating innate immune responses and limiting bacterial proliferation in zebrafish.