Genome-wide chromatin accessibility and transcriptome analysis reveal the up-regulation of immunosuppressive genes in macrophages under simulated microgravity

Long-term space missions are of growing research interest because of the space exploration. However, plenty of works focused on the impaired immune response, less attention has been paid to the activation of immunosuppressive or anti-inflammatory function. The molecular mechanism of immune disorder induced by microgravity still needs investigation. Here, we used a random positioning machine to generate a simulated microgravity environment and evaluated its effects on mouse RAW 264.7 macrophage cell line. We used ATAC-seq and RNA-seq for revealing the mechanism at chromatin level and gene level. From ATAC-seq, we obtained an average of 75,700,675 paired-end clean reads for each library and the mapping rates averaged at 96.8 %. The number of differential accessible regions were 510 for increased peaks, 638 for decreased peaks. From RNA-seq, we obtained 278 differentially expressed genes, of which 104 were down-regulated and 174 were up-regulated genes. Through ATAC-seq and RNA-seq multi-omics analysis, we identified a group of 17 genes. Then we chose 6 up-regulated genes (CD83, CEBPD, CXCR5, DUSP6, SEMA4B, TNFRSF22) that related to immunosuppressive function for further confirmation. The qRT-PCR results were consistent with sequencing results, which indicated that simulated microgravity leads to the up-regulated expression of immunosuppressive genes of macrophages. Taken together, our results offered novel insights for understanding the brief principles and mechanisms of simulated microgravity induced immune dysfunction to macrophage.