Mechanism by which treponema pallidum lipopeptides activates macrophages to produce cytokines and immunotolerance induced by the lipopeptides

doi:10.11786/sypfbxzz.1674-1293.20160404

Abstract：Objective To explore the possible mechanism by which treponema pallidum (TP) lipopeptides stimulates macrophages to produce cytokines and to investigate the immunotolerance induced by the lipopeptides in the NF-κB signaling pathway, so as to proivide a reference for improving the understanding of the immunological process of human infected by TP and interpreting the serofast phenomenon caused by TP infection. Methods The concentration of cytokines secreted by THP-1 cells under the stimulation of TP lipopeptides were tested by using ELISA. After blocking the CD14 receptor, the reaction of macrophages against lipopeptides was analyzed and the ability of the lipopeptides to induce immunotolerance of macrophages was evaluated. The expressions of intracellular signal transduction molecules were measured by western blot. Results The abilities of three types of lipopeptides to induce macrophages cells to secrete the cytokines IL-βand IL-8 progressively increased with the lipopeptide levels. The levels of both IL-1βand IL-8 signiifcantly decreased after blocking the CD14 receptor. The levels of both IL-1βand IL-8 produced by the immunotolerance induced by lipopeptides were considerably less than those resulting from direct stimulation. The protein expression levels of the signal transduction molecules TLR2 and NF-κB P65 signiifcantly decreased after the immunotolerance induced by lipopeptides. Conclusion Macrophages cells can be induced by three types of lipopeptides to produce IL-1βand IL-8. The downstream signaling pathway is activated by the lipopeptides through CD14 receptor on the membrane of macrophages to induce cytokine production. The lipopeptides may stimulate macrophages to create immunotolerance by activating the downstream NF-κB signaling pathway via TLR2 to reduce cytokines production. The immunotolerance induced by TP lipopeptides may be an important cause of the syphilis serofast phenomenon. Further study and veriifcation are still required.