Activation of Heterophils and Monocytes in Chicken with a Formulation Containing a Seaweed Extract from Ulva armoricana

Responsiveness to invasive pathogens, clearance via the inflammatory response, and activation of appropriate acquired responses are all coordinated by innate host defenses. We have previously demonstrated that a purified ulvan extract of Ulva armoricana is able to activate avian heterophils and monocytes in vitro and in vivo, leading to in vivo release of cytokines including interleukin 1 β (IL1β), interferon α (IFNα) and interferon γ (IFNγ), in a transient and dose-dependent manner. In this study, we used the same protocol to evaluate a formulated version of this extract, called Searup ® . Our experiments showed that a single oral administration of this product at the dose recommended for use in the farm, results in heterophils and monocytes activation. In heterophils, activation was evidenced by β-D-glucuronidase release and increased mRNA expression of IL1β, IFNα and IFNγ. In monocytes, the expression of IFNγ and inducible nitrite oxide synthase (iNOS) were also up-regulated. Finally, plasmatic NO increased significantly on day 1, decreased on day 2 and was no longer significant at day 3. A similar pattern was observed for β-D-glucuronidase and for the modifications of the transcription profiles in monocytes as well as in heterophils. The only notable exception is gene transcription of 2'-5' Oligoadenylate Synthase, which is maximal at day 2 in monocytes. Due to its protective role in virus infection, this may constitute an additional layer of protection for this class of pathogens. Together our results show that the formulated solution, Searup ®, similarly to the purified extract allow to activate monocytes and heterophils but with some variations in the cytokines profiles and may provide protection against a larger variety of pathogens.