The Effect Of PKG On The Expression Of ABCA1and The Secretion Of Inflammatory Cytokines In Macrophage Derived Fom Cells

Objective: To observe the effect of PKG on the expression of ABCA1which related to reverse cholesterol transport closely in the macrophage-derivedfoam cells, and the effect on the secretion of IL-6,IL-10,and TNF-α.Methods: THP-1monocytes were induced to become macrophages bytreating with160nM PMA. Then the macrophages were pretreated with50mg/Lox-LDL to become foam cells. There were four groups for the test,that they weremacrophage,foam cell,foam cell dealing with PKG agonist8-Br-cGMP, and withPKG inhibitor KT-5823.The morphology of THP-1cells,macrophages and foamcells were observed under microscope.The cellular lipid accumulation wasdetermined by Oil Red O staining. The expression of ABCA1protein in the cellsabove were assessed by Western blot.And the secretion of IL-6,IL-10,TNF-αinto the supernatant were detected by ELISA.Results: The THP-1cells were round or oral, single，suspending, and brightunder the macroscope. The macrophages were adherence, irregular or fusiform,stretching out with pseudopod.Cellular lipid was stained as deeper red in themacrophage-derived foam cells after incubated with50mg/L ox-LDL for48hours. The proportion of cellular lipid was more than50%in the cells,thatmeans the model of foam cell was succeeded.The expression of ABCA1protein in foam cells was decreased significantlythan that in the macrophages（P＜0.05）.After the macrophage-derived foamcells were treated with8-Br-cGMP，the expression of ABCA1protein was increased significantly than that in the foam cells（P＜0.05）.But decreasedsignificantly under the occation dealing with KT-5823（P＜0.05）.After the THP-1monocyte-derived macrophages were incubated with8-Br-cGMP，the secretion of IL-6in the supernatant was decreased significantly（P＜0.05）.And the secretion of IL-10increased significantly（P＜0.05）. Butthe expression of IL-10decreased significantly after the macrophages incubatedwith KT-5823（P＜0.05）.The expression of IL-6and TNF-α were increasedsignificantly in the foam cells than that in the macrophages(P＜0.05).Theexpression of IL-10has no difference between the two groups(P＞0.05).Afterthe macrophage-derived foam cells were incubated with8-Br-cGMP， theexpression of IL-6and TNF-α decreased significantly（P＜0.05）.And theexpression of IL-10increased significantly（P＜0.05）.If the macrophage-derivedfoam cells were treated with KT-5823，the expression of IL-6and TNF-α werealso decreased significantly（P＜0.05）.And the expression of IL-10decreasedobviously（P＞0.05）. The changing of IL-10expression into the supernatant wasjust opposite between the two groups which treated with8-Br-cGMP andKT-5823respectively.That means the expression of IL-10increased whentreated with8-Br-cGMP, and decreased when treated with KT-5823.It suggestedthat IL-10be as an anti-inflammatory cytokine in the macrophages may beconnected with PKG signaling pathway.Both of the expression of IL-6andTNF-α into the supernatant were the same decreased between the two groupstreated with8-Br-cGMP and KT-5823respectively.It seems that the regulationof IL-6and TNF-α expression may not be connected with PKG signalingpathway. The results above remained to be further studied.Conclusions: According to preliminary study works and the results of theseexperiments above, PKG maybe take part in the reverse cholesterol transport by regulation the expression of ABCA1.Then the lipid accumulation was arrest toinfluence the formation of foam cell. Meanwhile, PKG may up-regulation theexpression of anti-inflammatory cytokine, such as IL-10,and down-regulationthe expression of inflammatory cytokine(IL-6and TNF-α),to prevent thedevelopment of inflammation. In conclusion,it implied that PKG has a protentialanti-atherosclerosis function.The research work here will provide some newideas and new targets for the prevention and treatment of atherosclerosis.