Effect of simulated microgravity on lipopolysaccharide induced inflammatory cytokines release in human monocytic leukemia THP-1 cells

Objective To observe the effect of simulated microgravity on lipopolysaccharide (LPS)-induced inflammatory cytokines release in human monocytic leukemia THP-1 cells. Methods The human′s THP-1 cells were chosen as the research objects and divided into control group and simulated weightlessness group. After being resuscitated and subcultured, the cells in simulated weightlessness group were treated by clinostat with the speed of 30 r/min and cultured in the 37℃ incubator. The control group was set up synchronously with the experimental conditions that were consistent with simulated weightlessness group but without clinostat treatment. Six bottles of cells for each group had been tested for 3 times. When the cells in simulated weightlessness group were cultured in the clinostat for 48 h, 3 bottles of cell for each group were centrifuged for 5 min with the speed of 1 000 r/min. Then the LPS cell was added to stimulate cells with the concentration of 1 μg/ml and the cultivation lasted for 8 h. The cells and the cultured medium were collected by centrifugation. The other 3 bottles of control group and simulated weightlessness group were added equivalent volume cultured medium with LPS. The cells and the cultured medium were collected by centrifugation 8 h later. The experiment was repeated for 3 times. The mRNA expression and the changes of the concentration of TNF-α, IL-6, IL-1β gathered under 4 experimental conditions were compared. Results ①Compared with those in the control group, the mRNA expressions of TNF-α, IL-6 and IL-1β were increased significantly in LPS group and simulated weightlessness + LPS group (q=11.63-50.24, P<0.05); mRNA expressions of TNF-α and IL-1β were increased significantly in simulated weightlessness group (q=5.56-3.44, P<0.05). Compared with LPS group, the mRNA expressions of TNF-α and IL-6, IL-1β were increased significantly in simulated weightlessness + LPS group (q=9.08-26.50, P<0.01). ②Compared with those in control group, the concentration of TNF-α, IL-6, IL-1β were increased significantly in LPS group and simulated weightlessness group (q=3.02-32.52, P<0.05); the concentrations of TNF-α, IL-6 and IL-1β were increased significantly in simulated weightlessness + LPS group (q=40.02-65.31, P<0.01). Compared with those in LPS group, the concentrations of TNF-α and IL-6, IL-1β were increased significantly in simulated weightlessness + LPS group (q=17.59-32.79, P<0.01). Conclusions Simulated weightlessness can significantly increase the secretion of inflammatory cytokines and aggravate the LPS-induced inflammatory reaction in THP-1 cells. Key words: Weightlessness simulated; Lipopolysaccharides; Gene expression; Cytokines