Vaccination and immune response of the pituitary in fish

Article from the Special Issue on ISFSI 2019; Edited by Daniel Montero.-- Trabajo presentado en el 3rd International Conference of Fish & Shellfish Immunology (ISFSI 2019), celebrado en Las Palmas de Gran Canaria del 16 al 20 de junio de 2019.Although it is known that pituitary hormones can have a direct or indirect influence stimulating or suppressing the immune responses, whether there is a local immune response in this tissue or what is the effect of the immune stimulus on the pituitary function in fish has not received specific attention. In order to understand the immuno-endocrine interaction at the pituitary level, particularly the Hypothalamus-Pituitary-Interrenal axis, different experiments were carried out in rainbow trout and gilthead seabream using both in vitro and an in vivo approaches. Pituitaries of rainbow trout Oncorhynchus mykiss were cultured in vitro, incubated for 3h with Vibrio anguillarum bacterin, bacterin plus CRH, cortisol, human recombinant IL1β, or spleen medium, and then genes involved in pro-inflammation (il1β, il8, tnfα1, ifnγ), anti-inflammation (tgfβ1b, il10), or innate immune modulation (mhcIIa, c3, mif) were tested. Data showed that, incubation with bacterin alone and bacterin plus recombinant IL1β or CRH, as well as medium from bacterin-treated spleen caused significant up-regulation of pro-inflammatory genes, while down-regulated the anti-inflammatory gene tgfβ1b. Besides, recombinant IL1β plus bacterin or alone caused raise of mhcIIa and tnfa, respectively. A second experiment assessed the response of seabream vaccinated by means of an injection with Lactococcus garveiae and immune gene modulation was determined after 1h, 6h and 24 hours looking at the expression of the proinflammatory genes il1β, tnfa and cox2, the anti-inflammatory genes tgfβ1b, il10, and the innate genes lys and c3 corresponding to lysozyme and complement proteins. The immune genes il1β, cox2 and lys, showed a strong expression in the pituitary tissue after injection vaccination, notably il1β which showed more than 10 fold raise, thus indicating both a high sensitivity to the vaccine and the onset of a robust immune response in the pituitary at in vivo level. The overall results indicate that pituitary shows a relevant local immune gene equipment, and also the potential of fish pituitary to develop both innate and adaptive immune responses.Peer reviewe