Trichostatin A Inhibits Cytokines Released in LPS-Induced THP-1 Cells via Downregulating Deacetylated-Syntaxin 17 and Promoting Autophagosome-Lysosome Fusion.

Sepsis is a complicated disorder caused by infection, which may trigger various symptoms. Lipopolysaccharides (LPS) are among the primary pathogens which can stimulate host's immunoreaction. In the late stage of sepsis, the patients' immune system is significantly suppressed, thus the mortality increases. Notably, autophagy is pivotal during sepsis, in which autophagosome-lysosome fusion mediated by syntaxin 17 (STX17) is a key step. Previous studies have shown that histone deacetylase 2 (HDAC2) deacetylated STX17 to promote autophagosome-lysosome fusion. Trichostatin A (TSA) as a HDAC inhibitor (HDACi) has the capability of inhibiting histone deacetylase activity, while such an effect can be reversed by ITSA-1. This time LPS was used to stimulate human monocyte-macrophages (THP-1 cells) to establish the inflammatory cell model. TSA and ITSA-1 were administrated. The cell proliferation was examined by WST-1. Cytokines such as TNF-? and IL-6, as well as HDAC2 activity and deacetylated STX17 (DA-STX17) expression were detected by ELISA. Also, autophagy-related proteins such as P62 and microtubule-associated protein light chain 3 (LC3) were detected by Western Blotting (WB), and autophagosome-lysosome fusion was observed by fluorescence assay. Cell apoptosis was measured by flow cytometry. Besides, network pharmacology analysis was conducted. The data showed that TSA inhibited HDAC2 activity, and remarkably downregulated DA-STX17 expression, accompanied by the lower expression of P62 and LC3 ?/I. Decreased DA-STX17 promoted autophagosome-lysosome fusion, and inhibited TNF-? secretion. Furthermore, network pharmacology analysis revealed an inner relationship concerning HDAC2 between TSA and sepsis. Therefore, TSA can be considered a potential drug to cure sepsis-related diseases.