Effects of culture temperature on antioxidant capacity andinflammatory responses of LPS-induced macrophages from head kidney oflarge yellow croaker (Larimichthys crocea)

To study the effects of culture temperature on antioxidant capacity and inflammatory responses of Larimichthys crocea macrophages, macrophages were isolated from head kidney of L. crocea and resultant monolayer was maintained at 16 °C, 22 °C and 28 °C, respectively. After adding 25 μg/mL LPS medium to macrophage monolayer for 2 h, cell viability, respiratory burst activity, antioxidant enzyme activities and gene expressions together with IL-1β and Hsp70 mRNA expressions of macrophage cultured at different temperatures were evaluated. Results showed that cell viability of macrophages placed at 16 °C and 22 °C was significantly higher than cells cultured at 28 °C after incubation for 36 h. LPS could significantly promote the respiratory burst activity and inhibited the activities of SOD and CAT enzymes. Macrophage incubated at high temperature (28 °C) showed significantly higher CAT enzyme activity and gene expression, whereas no significant difference was found in SOD enzyme activity and gene expression. LPS triggered potent pro-inflammatory response with IL-1β being the indicative parameter, which was inhibited by high culture temperature. However, transcript levels of Nrf2 and Hsp70 increased with the rise of temperature to a significant extent, and both gene expressions were markedly enhanced by LPS compared to control groups. Taken together, all the results in the present study indicated that temperature may regulate the antioxidant capacity and inflammatory responses of LPS-induced macrophages from head kidney of L. crocea through pathways involving Nrf2 and Hsp70.