Effects of simulated microgravity on the structure, immune cell and cytokine expression of the spleen in rhesus monkey / 解放军医学杂志

ABSTRACT

Objective To investigate the effects of simulated microgravity on the structure, expression of surface molecules of immune cells and the expression of cytokines in the spleen of rhesus monkey. Methods Fifteen rhesus monkeys were employed as the research objects, and randomly assigned into three groups (5 each) normal control (NC) group, simulated microgravity (SM) group and microgravity recovery (MR) group. A posture with head down for –10° was set for monkeys to simulate microgravity. All the rhesus monkeys were sacrificed under anesthesia after experiments completion. Spleen tissues were harvested and HE and immunohistochemically stained to observe the general structure of the spleen tissues in each group and detect the expressions of surface molecules (CD3, CD4, CD8, CD20 and CD68) in immune cells, and the expressions of related cytokines (IL-1, IL-5, IL-6, IL-17, IL-18, IL-22 and IL-23) on the splenic immune cells. Results Compared with the normal structure of spleen tissues in NC group, the dividing lines between red and white pulp were not clear, the white pulp and the periarteriolar lymphoid sheath were decreased, and the lymphocytes arranged disorder in SM group. The expressions of CD3, CD4 and CD20 decreased and of CD8 increased significantly in SM group (P<0.05). The production of IL-5 was significantly lower in SM group than in NC and MR groups (P<0.05). Conclusions Simulated microgravity may cause spleen tissue damage and throw an influence on the quantity of CD3+ T-cell, CD4+ T-cell, CD8+ T-cell and CD20+ B-cell in rhesus monkey. Homogeneously, the production of IL-5 is decreased in spleen of rhesus monkey under simulated microgravity. These effects may be related to the damage of immune system under simulated microgravity.