LPS Induces An Impaired Adaptive Immune Response In Macrophages After Long-term Stimulation

In a different environment, macrophages, as strong plasticity cells, can be polarized into different phenotypes. In the researches regarding the phenotypes and functions of macrophages, lip polysaccharide (LPS) was used as a short-time stimulator to activate macrophages, but it is unclear which phenotype of macrophages will be chosen after a long-term (48h) LPS inducement. This study established a macrophage model from peripheral blood mononuclear cell-derived monocyte in vitro for the investigation on the phenotypic effects by the LPS simulation for48h. The effects from the phenotypic transformation on the functions of the macrophages and the related mechanism were also explored.AIMS:To establish in vitro immunosuppressive macrophage model and to study the immunosuppressive phenotypic features of macrophages.Methods:We used ficoll-hypaque density gradient centrifugation combined with MicroBeads separation kits to separate peripheral blood mononuclear cells from blood, and then induced the monocytes into macrophages. We observed the morphology of the macrophages by treating the cells with LPS for48hours, in comparison with a negative control and IFN-y treatment. ELISA was used to detect the level of cytokines (IL-10/IL-12/IL-6/TNF-α) and Flow Cytometer was used to detect the expression of surface molecules (HLA-DR/CD14/CCR7/HLA-ABC/CD40). To observe the macrophage impact T cell proliferation, we put them co-culture for6days. Quantitative PCR was used to validate the expression level of MyD88independent pathway related molecules in TLR-4signal pathway.Results:The antigen presentation ability of macrophages was reduced and the IL-10expression level was increased after the cells were treated with LPS for48hours. We co-cultured LPS-MΦ with CD3+T cells for6days and observed a poor proliferative capacity of CD8+T cells. Real-time PCR results indicated that TRIF, IRF3and CIITA were down-regulated in LPS-M(?).Conclusion:We successfully established a macrophage model in vitro and observed that LPS induced macrophages into an immunosuppressive phenotype with poor CD8+T cell proliferative capacity, in which MyD88independent signaling pathway was impaired.