In vitro evaluation of immunomodulatory activity of total extracts of Canelo (Drimys winteri) and active compound polygodial in salmon head kidney cells.

In recent years has intensified the search for natural stimulant of the immune system (immunomodulators), which are considered as a powerful tool for the aquaculture industry, as it strengthens the immunity, disease resistance and stress. This work presents the evaluation of in vitro immunomodulatory activity of total extract of Canelo (Drimys winteri) and its isolated active compound polygodial in macrophage-like cell line ASK-1 (Atlantic salmon head kidney cells). We examined the expression of three immune molecular markers: interferon a (IFNa), interleukin 1b (IL-1b) and the major histocompatibility complex class II receptor (MHCII) by QRTPCR. Both extracts showed a fast and significant increase in expression of IL- 1b similarly to the one observed in the presence of commercial imunomodulator. Moreover, the expression of IFNa and MHCII showed a significant increase versus control when stimulated with polygodial, similarly to the commercial inductor, being less significant increase in expression of these markers when the cells are stimulated with total extract of Canelo. Additionally, based upon our previous results of the antisaprolegnia activity of these extracts when studied Saprolegnia parasitica grown directly on agar plates, we decided to evaluate the effect of these extracts in an acute infection assay using this oomycete in ASK-1 cells. Preincubation with total extract of Canelo or polygodial and subsequent acute infection with Saprolegnia showed a significant increase in expression of IL-1b versus control, without observing a greater difference when Saprolegnia is incubated without extracts. Furthermore, during acute infection with Saprolegnia a down regulation of IFNa and MHCII expression was observed, suggesting interference of immune function in these macrophage-like cells, which could limit the response of the host. However, the pre-incubation with total extract and especially polygodial produced an increase of these markers expression when ASK-1 cells where acutely exposed to Saprolegnia. Our results suggest the transfer of the immunomodulatory properties to this vitro model, which potentially woud allow the recognition and defense against these pathogens.