Effects of anti-Siglec-9 antibody Fab fragment on LPS-induced inflammatory responses in macrophages

The objective of this study is to investigate the role of the Fab segment of the anti-Siglec-9 antibody in macrophages induced by Human acute monocytic leukemia cells on LPS-induced inflammatory responses, and to explore the mechanism involved. The mRNA levels of inflammatory cytokines, including TNF-α, IFN-β, IL-1, IL-6 and IL-10 were detected by real-time fluorescence quantitative PCR. The protein levels of these cytokines were detected by ELISA. Finally, the mechanism of the inflammatory response induced by the anti-Siglec-9 antibody Fab segment in dendritic cells was investigated by Western blot. The expression of inflammatory cytokines was found to be affected by the Siglec-9 antibody Fab segment, as determined by Western blot analysis. In comparison with the LPS group, the Fab segment of the anti-Siglec-9 antibody demonstrated the capacity to inhibit pro-inflammatory cytokines, elevate the expression of anti-inflammatory cytokines at the mRNA and protein levels, and decrease the phosphorylation levels of TLR4 signaling pathway proteins P38, ERK, IKK and TBK. It can be concluded that the Fab segment of the anti-Siglec-9 antibody has the capacity to inhibit the expression of inflammatory cytokines at both the mRNA and protein level by blocking the TLR4 signaling pathway.