Spatial regulation of CD14-like epitope in hematopoietic and ocular tissues of cultured North Atlantic lumpfish (Cyclopterus lumpus) and spotted wolffish (Anarhichas minor) during bacterial infection and temperature variations

The development of new tools for a better understanding of innate immune mediated responses to tissue damage in emerging model organisms could offer novel approaches to inform toxicology, disease mitigation and/or drug discovery. Innate immunity is one of the first lines of defence in response to tissue damage, with macrophages being key players in these processes. The expression of macrophage protein markers in North Atlantic marine teleost fish has not been extensively studied. Here we used an anti-mammalian-CD14 antibody to explore CD14 epitope expression in hematopoietic and ocular tissues of lumpfish and spotted wolffish. Western blotting indicated that proteins reactive with an anti-mammalian-CD14 antibody with similar molecular weights to mammalian CD14 isoforms exist in both lumpfish and spotted wolffish. Immunohistochemistry (IHC) analysis using this anti-mammalian-CD14 indicated CD14-like reactive epitope expression in head kidney and ocular choroid rete mirabile in both normal healthy lumpfish and in a Vibrio anguillarum marine bacterial pathogenesis paradigm. As infection proceeded in lumpfish, CD14-like expression increased in head kidney and ocular choroid rete mirabile vasculature as revealed by IHC. In addition, we also used a temperature challenge paradigm in spotted wolffish to assess CD14-like reactivity in ocular choroid rete mirabile. A six-week hypothermal condition led to higher levels of CD14-like expression in the wolffish choroid rete mirabile than control temperature or a six-week hyperthermal condition as revealed by IHC. The tissue spatial regulation of CD14 epitope in lumpfish and spotted wolffish we observed herein might serve as a tool in emerging novel model organism-based technologies toward a better understanding of the mechanisms involved in responses to tissue damage.