Development and use of a Chinook salmon spleen stromal-like cell line to study the cellular immune response to Vibrio anguillarum

Despite increased interest in Chinook salmon aquaculture, there is inadequate understanding regarding the bacterial immune defenses of this species. This study describes the establishment and characterization of a continuous stromal-like cell line derived from Chinook salmon spleen, CHST, and its response to a heat-killed bacterial exposure challenge. Optimal growth of CHST was seen at 18 °C when grown in Leibovitz's L15 media supplemented with 20 % fetal bovine serum. DNA analyses confirmed that CHST did originate from Chinook salmon tissue. Vibrio anguillarum, a common pathogen of marine aquaculture and the causative agent of an acute hemorrhagic septicaemia known as vibriosis was used for exposure studies. V. anguillarum was heat-killed and CHST was challenged so that pro-inflammatory (IL-1β, IL-6 and TNFα) as well as anti-inflammatory (IL-10) cytokine transcript levels could be measured at 1, 4, 12, 24 and 96 hour (h) post-exposure. The heat-killed bacteria were observed to significantly stimulate the expression of all three pro-inflammatory cytokines at 4, 12, 24 and 96 h post-exposure with the peak in expression occurring at 12 and 24 h. Meanwhile, IL-10 was not observed to significantly increase until 96 h post-stimulation, which was also the time when the inflammatory cytokine expression was decreasing. The establishment and characterization of CHST provides a valuable model for studying the immune response of Chinook salmon stromal-like cells in response to stimuli, including those of bacterial origin.