Simulated Microgravity can Promote the Apoptosis and Change Inflammatory State of Kupffer Cells

Abstract

Objective: In this study, we analyzed the transcriptome sequences of Kupffer cells exposed to simulated microgravity for 3 d and conducted biological experiments to determine how microgravity initiates apoptosis in Kupffer cells.

Methods: Rotary cell culture system was used to construct a simulated microgravity model. GO and KEGG analyses were conducted using the DAVID database. GSEA was performed using the R language. The STRING database was used to conduct PPI analysis. qPCR was used to measure the IL1B, TNFA, CASP3, CASP9, and BCL2L11 mRNA expressions . Western Blotting was performed to detect the level of proteins CASP3 and CASP 9. Flow cytometry was used to detect apoptosis and mitochondrial membrane cells. Transmission electron microscopy was used to detect changes in the ultrastructure of Kupffer cells.

Results: Transcriptome Sequencing indicated that simulated microgravity affected apoptosis and the inflammatory state of Kupffer cells. Simulated microgravity improved the CASP3, CASP9, and BCL2L11 expressions in Kupffer cells. Annexin-V/ PI and JC-1 assays showed that simulated microgravity promoted apoptosis in Kupffer cells. Simulated microgravity causes M1 polarization in Kupffer cells.

Conclusion: Our study found that simulated microgravity facilitated the apoptosis of Kupffer cells through the mitochondrial pathway and activated Kupffer cells into M1 polarization, which can secrete TNFA to promote apoptosis.

Keywords: Apoptosis; Kupffer cell; Microgravity; Polarization.