Involvement of p42/p44 MAPK, p38 MAPK, JNK, and NF-κB in IL-1β-induced VCAM-1 expression in human tracheal smooth muscle cells

Interleukin-1β (IL-1β) has been shown to induce the expression of adhesion molecules on airway epithelial and smooth cells and contributes to inflammatory responses. Here, the roles of mitogen-activated protein kinases (MAPKs) and nuclear factor-κ (NF-κB) pathways for IL-1β-induced vascular cell adhesion molecule (VCAM)-1 expression were investigated in human tracheal smooth muscle cells (HTSMC). IL-1β induced expression of VCAM-1 protein and mRNA in a time-dependent manner, which was significantly inhibited by inhibitors of MEK1/2 (U0126 and PD-98059), p38 (SB-202190), and c-Jun NH ₂-terminal kinase (JNK; SP-600125). Consistently, IL-1β-stimulated phosphorylation of p42/p44 MAPK, p38, and JNK was attenuated by pretreatment with U0126, SB-202190, or SP-600125, respectively. IL-1β-induced VCAM-1 expression was significantly blocked by the specific NF-κB inhibitors helenalin and pyrrolidine dithiocarbamate. As expected, IL-1β-stimulated translocation of NF-κB into the nucleus and degradation of IκB-α were blocked by helenalin but not by U0126, SB-202190, or SP-600125. Moreover, the resultant enhancement of VCAM-1 expression increased the adhesion of polymorphonuclear cells to a monolayer of HTSMC, which was blocked by pretreatment with helenalin, U0126, SB-202190, or SP-600125 before IL-1β exposure or by anti-VCAM-1 antibody. Together, these results suggest that in HTSMC, activation of p42/p44 MAPK, p38, JNK, and NF-κB pathways is essential for IL-1β-induced VCAM-1 gene expression. These results provide new insight into the mechanisms of IL-1β action that cytokines may promote inflammatory responses in airway disease.