The Effect Of P-selectin On The Maturation Of Dendritic Cells From Human Peripheral Blood

Background: Atherosclerosis is a disease of large and medium-sized muscular arteries.It is characterized by lipid accumulation, vascular inflammation and cell death. The arteries become narrow and less flexible due to the progression of the disease. If the arteries to heart and brain affected, causing flow limitation, peopele may have a heart attack. or a stroke which are the most severe clinical envents. Every year millions of people suffer from these two kinds of fatal disease, making it the leading cause of death in some developed countries.The exact cause of atherosclerosis is still unknown. Atherosclerosis may be caused by a response to chronic inflammation. Although these immune responses initially play a part in the removal of potentially harmful antigens. However studies confirmed the activation of immune responses is pro-atherosclerosis. Some people regard atherosclerosis as an autoimmune disease. The inflammatory disorder involves both the innate and adaptive of the immune response. Dendritic cells (DCs) play an important role in the pathogenesis of atherosclerosis.Dendritic cells (DCs), named for their tree-like shapes, are the most important antigen presenting cells (APCs). They possess the ability to stimulate naive T cells Their immune function depends on their maturation. Maturation DCs possess a special morphology, phenotype and function. DCs are derived from bone marrow progenitors. There are two kinds of DCs: myeloid DCs(mDCs) and lymphoid DCs(pDCs). In most tissues, DCs are present in immature state and are unable to stimulate T cells. Once they have captured antigens, they possess the ability of taking up and processing of antigens, subsequently undergoing maturation. They migrate.into lymphoic organs where interact with T cells inducing an immune response. In healthy individuals DCs form a network in the arterial playing a role of immune surveillance. Recently DCs were found in atherosclerosis plaques.And they reside in the plaque shoulder which is the regions prone to rupture. The cell adhesion molecule P-selectin is one of selectin families. The inflammatory response is initiated by rolling of circulating leukocytes on endothelium. P-selectin is partially responsible or the adhesion of DCs to the endothelium.Studies have shown the important role of P-selectin in the process of atherogenesis. Increased P-selectin expression has been demonstrated on active atherosclerotic plaques. P-selectin in patients of coronary artery disease shows a higher level as compared to healthy individials. So we think P-selectin have relationship with the stabilization of atherosclerosis.Objective: To investigate the effect of P-selectin,a significant adhesion molecule in atherosclerosis,on the maturation of dendritic cells (DCs) in vitro.Method: CD14~+ monocytes were isolated from human peripheral blood by magnetic cell sorting (MAC).After 6 days'culture in RPMI1640 medium with recombinated human granuloeyte-macrophage colony-simulating factor (rhGM-CSF, 100ng/ml) and recombinated human interleukin-4 (rhIL-4 50ng/ml),cells were divided into four groups. They were stimulated by 100ng/ml P-selectin or 100mg/ml P-selectin and 5ug/ml P-selectin antagonist for 24 hours. Non-stimulated DCs and LPS stimulated DCs severed as negative and positive control. Electron microscope examined morphology feature of four group cells. Flow cytometric analysis(FACS) was used to investigate the imunophenotypic expression. Immune function was evaluated by mixed lymphocyte reaction(MLR). The expression of Toll-like receptor 4(TLR-4)determined by RT-PCR.Results: A large number of DCs with higher purity that were isolated from human peripheral blood. Dendritics of P-selecting stimulated DCs rised obviously. Compared with non-stimulated and P-selectin antagonist stimulated DCs,P-selectin stimulated DCs up-regulated the expression of maturation markers CD83, CD1a,and co-stimulating molecules CD80, CD86. P-selectin stimulated DCs could efficiently stimulate T lymphocytes cells proliferation. The mRNA of TLR-4 in P-selectin stimulated DCs was higher than that of non-stimulated DCs. P-selectin antagonist could inhibit the exrpession of TLR-4 and maturation markers.Conclusion: P-selectin could promote the matuation of DCs. These DCs had typical dendritic-like shapes, highly expressed maturation markers, stimulated T cells proliferation, and up-regulated the expression of TLR-4 mRNA. The mechanism might be related with NF-κB. P-selectin antagonist could inhibit the matuation, but the effect is not complete.