The Effects of Simulated Microgravity on Immune Function of Macrophages

Since the 1 960 s,many successful space missions have highlighted the advantages and necessity of humans in the exploration of space,but scientists have long worried about the adverse effects of spaceflight on Astronaut.Space flight and models that create conditions similar to those that occur during space flight have been shown to deleteriously affect a variety of immunological responses.The mechanisms and biomedical consequences of these changes remain to be established.Conducting experiments in an environment of true microgravity requires a roundtrip ticket into space,a feat that is both expensive and challenging.Simulated microgravity(SMG)models allow scientists to gather preliminary data without the cost and logistical challenges of spaceflight.The objective of the present study was to evaluate the effects of SMG on immunity function of macrophages that exposed to RPM and RCCS separately.While many studies have demonstrated that alterations occur in the immune system as a result of space travel,the level at which these mechanisms exert their effect,at the level of the mature immune cell or earlier at the progenitor or stem cell stage is not known.In particular,macrophages,as one of the most important immune cells and play a key role in both specific and non-specific immunity,did not have received much attention.Therefore,in our study,we mainly study the influence of microgravity on the immune function of macrophages.In this study,we evaluated the immune dysfunction of macrophages under SMG.Firstly,we found that the morphology and structure of the macrophages were changed,specifically,we observed that there were more protrusions on cell surface and the cells were shrinking significantly after exposure to SMG.Secondly,we demonstrated that under simulated microgravity(SMG)conditions,the phagocytic and proliferative functions of macrophages were significantly reduced.Thirdly,several processes,including surface receptor expression,cytoskeleton,and cytokines secreted were investigated in macrophages under SMG.Phagocytosis is one of the important means for macrophages to exert immune function,and cell surface phagocytosis-related receptors play an important role.Here,we selected four common receptors(TLR2,FcyR1,CD11b and CD 18)to detect.The results indicate that SMG(RPM and RCCS)have a great influence on the expression of surface phagocytosis-related receptors,which may be one of the main reasons for the decline of immune function ofmacrophages.Macrophages exert immune function through phagocytosis,and the cytoskeleton plays an important role in the process of phagocytosis.The results indicate that SMG(RPM and RCCS)have a great influence on the expression of cytoskeleton-related proteins,which provides me with a new idea that SMG may regulate immunity of macrophage by affecting the cytoskeleton.Immune-related cytokines play an important role in macrophage immune process.Here,we selected four common immunocytokine(TNF-α,IL-1β,IL-6 and IL-10)to detect.The change of these four immunocytokine further demonstrate that SMG significantly decline the immunity of macrophage,we must pay enough attention to the impact of SMG on macrophage.The above factors such as the changes of morphology and structure of the macrophages and the decreased expression of Arp2/3 complex related proteins,cytokine secretion,and cell surface receptors may be responsible for the immune dysfunction of macrophages under SMG.