Effects of interaction between dengue virus type 2-infected HUVECs and human CD4+ T cells on the expression of adhesion molecules and immunosuppressive factors

Abstract

Objective To investigate the effects of interaction between human umbilical vein endothelial cells (HUVECs) which were infected with dengue virus type 2 (DENV-2) and CD4+ T cells on the expression of ICAM-1 (intercellular adhesion molecule 1), VCAM-1 (vascular cell adhesion molecule 1), IL-10 and TGF-β1 at mRNA level for further understanding the immunological mechanism of DENV infection. Methods HUVECs were treated with CYM-5442, a selective agonist for sphingosine-1-phosphate receptor 1 (S1P1), for 24 hours and then infected with 103 TCID50 (50% tissue culture infective dose) of DENV-2 before co-culturing with CD4+ T cells. Changes in the expression of NS1 (DENV-2 nonstructural protein), SPHK1 (sphingosine kinase 1, phosphorylating sphingosine to S1P), ICAM-1, VCAM-1, IL-10 and TGF-β1 at mRNA level were detected by real-time PCR after 4, 8, 12, 24, 48 and 72 hours of co-culturing. Results There was a certain timeliness in the expression of NS1 at mRNA level after infecting HUVECs with DENV-2 and the expression reached a peak at 24 h. Treating HUVECs with or without CYM-5442 had no significant influence on the expression of DENV-2 NS1 at mRNA level. The expression of SPHK1 at mRNA level was significantly increased after treating HUVECs with CYM-5442 and DENV-2 (P<0.05). Compared with DENV-2-infected or untreated HUVECs, Co-culturing DENV-2-infected HUVECs with CD4+ T cells increased the expression of ICAM-1 and VCAM-1 in HUVECs at mRNA level (P<0.01) as well as the expression of IL-10 in CD4+ T cells at mRNA level (P<0.05), but had no significant influence on the expression of TGF-β1 in CD4+ T cells at mRNA level. Conclusion This study shows that DENV-2 can replicate and proliferate in HUVECs, but CD4+ T cells inhibit the replication and proliferation. CD4+ T cells play an important role in promoting the expression of VCAM-1 and ICAM-1 in DENV-2-infected HUVECs at mRNA level, activating HUVECs and increasing inflammation, which may be associated with increased vascular permeability induced by DENV-2 infection. Co-culturing CD4+ T cells with DENV-2-infected HUVECs promotes the expression of IL-10 in CD4+ T cells at mRNA level, but has no significant effect on TGF-β1. Key words: HUVEC; CD4+ T cell; DENV-2; Cytokine; Immunoregulation