Beta-adrenergic receptor stimulation influences the function of monocytes/macrophages in ayu (Plecoglossus altivelis)

Abstract

Adrenergic receptors (ARs) are members of the G-protein-coupled receptor superfamily that can be categorized into αARs and βARs. The specific function of ARs in teleost monocytes/macrophages (MO/MФ) remains unknown. We determined the cDNA sequence of ARs from ayu (Plecoglossus altivelis; PaαAR and PaβAR). Sequence comparisons showed that PaαAR was most closely related to the αAR of the Japanese flounder and Nile tilapia, while PaβAR was most closely related to the βAR of Atlantic salmon. The AR transcripts were mainly expressed in the spleen, and their expression was altered in various tissues upon infection with Vibrio anguillarum. PaαAR and PaβAR proteins were upregulated in MO/MФ after infection, and PaβAR knockdown resulted in a pro-inflammatory status in ayu MO/MФ upon V. anguillarum infection and lowered the phagocytic activity of MO/MФ. Our results indicate that PaβAR plays the role of an anti-inflammatory mediator in the immune response of ayu against bacterial infection.

Keywords: Adrenergic receptors; Anti-inflammation; Ayu; Monocytes/macrophages; Phagocytic activity; RNAi.