Sulphoraphane inhibited the expressions of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 through MyD88-dependent toll-like receptor-4 pathway in cultured endothelial cells

Background and aimsChronic inflammation plays pivotal roles in both cancer and cardiovascular diseases. A large body of evidence suggests that high intake of cruciferous vegetables is closely related with low risk of these disorders. However, the underlying mechanisms of protection are not fully understood. The aim of this study is to test the protective effects of an isothiocyanate sulphoraphane on inflammatory injury and related regulation pathways in cultured endothelial cells.Methods and resultsThe expressions of adhesion molecules were determined by TaqMan real-time polymerase chain reaction (PCR) and Western blot analysis. Nuclear factor-kappa B (NF-кB) translocation was detected by immunofluorescent hybridisation. Other proteins were measured by Western blot analysis. The results demonstrated that sulphoraphane significantly suppresses the expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 stimulated by lipopolysaccharide (LPS) both at the transcriptional and translational levels. In addition, sulphoraphane inhibited the translocation of NF-кB into the nucleus. Sulphoraphane decreased the phosphorylation of extra-cellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), while further blockade and activation using individually specific agents confirm that p38 MAPK and JNK are mainly involved. Interestingly, sulphoraphane down-regulated Toll-like receptor (TLR)-4, a receptor of LPS located on the membrane. In addition, MyD88, an effector downstream TLR-4 signal pathway was subsequently attenuated.ConclusionTaken all together, adhesion molecules are confirmed to be the novel targets of sulphoraphane in preventing inflammatory insult to endothelial cells. Sulphoraphane suppressed TLR-4 followed by MyD88 and downstream factors such as p38 MAPK and JNK, ultimately blocking NF-кB translocation and the subsequent expression of adhesion molecules. These data suggested a novel inflammatory pathway mediated by sulphoraphane.