ABSTRACT
BACKGROUND: Infiltration of eosinophils and activated T cells into the airway is a characteristic feature of allergic inflammation such as asthma. IL-4 has been shown to mediate adhesion of eosinophils and T cells to endothelial cells by inducing VCAM-1 expression on endothelial surface. IL-13 shares a number of biologic properties with IL-4. OBJECTIVE: We aimed to investigate the effects of IL-13 on the adhesion of eosinophils to human umbilical vein endothelial cells (HUVEC) and on the expression of VCAM-1 in HUVEC. METHOD: HUVEC was incubated for 24h with IL-13 (10ng/ml), IL-4 (10ng/ml) and TNF-a (10ng/ml). Surface expression of VCAM-1 in HUVEC was detected using irnmuno-cytochemical stain and reverse transcription-polymearse chain reaction (RT-PCR), and the adhesion of eosinophils to HUVEC was quantitated using eosinophil peroxidase (EPO) assay. RESULTS: The VCAM-1 expression on IL-13-treated HUVEC increased more than in the expression on medium-treated HUVEC (p<0.05). The adhesion of eosinophil to IL-13- treated HUVEC also increased more than in the adhesion to medium-treated HUVEC (p<0.05). The VCAM-1 expression was synergistically induced by TNF-a and IL-13 (p<0.05). IL-13 induced VCAM-1 expression and adhesion of eosinophils to HUVEC, similar to IL-4. IL-13 also induced VCAM-1 mRNA expression, with greater expression than with medium and TNF-a(p<0.05). IL-13-induced surface VCAM-1 was associated with expression of mRNA transcripts and adhesion of eosinophils to HUVEC(r=0.89, r=0.93, p<0.05). CONCLUSION: These findings demonstrate that IL-13 stimulates HUVEC to express surface VCAM-1 and has a possible role in promoting VCAM-1/VLA-4 dependent accumulation of eosinophils during allergic and other inflammatory responses.