The Influence Of VIP On Antigen-presenting Molecules Associated With Gastric Cancer Expressed On Dendritic Cells In Vitro

Background:Gastric cancer is one of the most common malignant tumors, the underlyingmechanisms gastric cancer cells how to escape the body’s immune are not fullyunderstood. Prior studies suggest that gastric cancer cells can secreteimmunosuppression vasoactive intestinal peptide hormone (vasoactive intestinalpeptide, VIP), so, whether the VIP can inhibit the expression of antigen-presentingmolecules on dendritic cells (dendritic cells, DC) during antigen-presenting process?So, gastric cancer cells can inhibit the capacity of antigen-presentation of DC throughsecreting VIP, thereby inhibit the body’s immune clearance. In order to verify thistheory, we designed this experiment.Dendritic cell vaccine used in gastric cancerimmunotherapy is a research hotspot currently. DC-SIGN (CD209) is the mostimportant surface receptor in C-type lectin receptors(CLR) family of dendritic cell,and it can participate in tumor immune escape. The formerly studies suggest that theexpression of immunosuppressive VIP and Ii chain (invariant chain, Ii chain,CD74) isincreased in malignant tumor gastric cancer.Therefore, Gastric cancer cells mayinhibit DC’s immune surveillance by the secretion of VIP which can adjust theexpression of DC-SIGN (CD209) and Ii chain (CD74) and thus participate in theimmune escape of stomach cancer.Objective:To observe the expressions of dendritic cells DC-SIGN and Ii chain,MHC-Ⅱ,and the collaborative costimulatory molecules CD40, CD80, CD86, whenco-incubated with gastric cancer cells and vasoactive intestinal peptide (VIP). Toevaluate the relationship between the expression of vasoactive intestinal peptide andimmune escape mechanism of gastric cancer. Methods:Cord blood was collected under strict aseptic collection from health cesareanpregnant volunteers were hospitalized in the First Affiliated Hospital of NanchangUniversity to obtain cord blood mononuclear cells(CBMC) by density gradientcentrifugation, the adhesion cells, collected among the CBMC, were stimulatingcultured in the medium containing cytokine-recombinant human granulocyte-macrophage colony-stimulating factor (rh GM-CSF), recombinant humaninterleukin-4(rh IL-4) to induce immature dendritic cells, and recombinant humantumor necrosis factor (rh TNF-α) were added on fifth day to induce mature dendriticcells. Mature dendritic cells were collected on tenth day,and co-incubated with gastriccancer cells, vasoactive intestinal peptide and Mannan which is natural ligand ofDC-SIGN respectively, just only dendritic cells is the control group. Then, detect theexpressions of dendritic cells’ DC-SIGN and Ii chain, MHC-Ⅱ, and the collaborativecostimulatory molecules CD40, CD80, CD86by immunocytochemistry and RT-PCR.,and analyze the impact of vasoactive intestinal peptide on the various immunemolecules expressed on dendritic cells when co-incubated with gastric cancer cells,and assess its role in gastric cancer immune escape finally.Results:1. With the induction of incubation time, dendritic cells express DC-SIGN(CD209), Ii chain (CD74), MHC-Ⅱ and synergistic costimulatory molecul es CD40,CD80, CD86more and more. The10th day of each DC indicators expression wassignificantly higher than the8th,9th day (p<0.05), and there is no difference betweenthe8th day and9th day (p>0.05).2. Mature dendritic cells express the receptors of VIP on surface, do not secretVIP.3. The expression of mRNA of DC-SIGN (CD209), Ii chain (CD74), MHC-Ⅱand collaborative costimulatory molecules CD40, CD80, CD86is consistent withcorresponding protein in each group. Human gastric cancer cell lines MKN45caninhibit the indicators from the mRNA and protein levels, VIP can further inhibit theindicators from the mRNA and protein levels when co-incubated with gastric cancer cells,and this effect can not be blocked by Mannan.4. The expression of DC-SIGN (CD209) and Ii chain (CD74), MHC-Ⅱ, CD40,CD80, CD86are positive correlation. The decrease of DC-SIGN (CD209) can inhibitdendritic cells’ antigen-presenting ability, and suppress its immune response.Conclusions:VIP can inhibit the expression of DC-SIGN (CD209), Ii chain (CD74), MHC-Ⅱand collaborative costimulatory molecules CD40, CD80, CD86of mDCs, inhibitdendritic cells’ antigen-presenting ability, and take part in the immune escape ofgastric cancer.