ホルボールエステル処理したTHP-1細胞におけるIL-4/IL-13刺激によるSTAT6リン酸化に対するスフィンゴシン1-リン酸2型受容体の役割

抄録

Previously we found that in bleomycin-administered sphingosine 1-phosphate receptor 2 (S1P₂) knockout mice, phosphorylation of STAT6, a transcription factor which is activated downstream of interleukin (IL)-4/IL-13, in broncho-alveolar lavage fluids cells was diminished compared with wild-type mice (PLoS One, 2018). In this study, we examined the role of S1P₂ on STAT6 activation using THP-1 cells differentiated with phorbol 12-myristate 13-acetate (PMA) as a model for macrophages (MΦs). Quantitative PCR analysis showed that THP-1 cells expresses S1P₂. We examined the responses of PMA-treated THP-1 MΦs to chronic stimulation with IL-4/IL-13 in the presence of S1P. IL-4/IL-13 stimulation induced a strong increase in STAT6 phosphorylation in PMA-treated THP-1 MΦs. The major signaling pathway of S1P₂ is a Rho–Rho kinase pathway. Pretreatment of PMA-treated THP-1 MΦs with the S1P₂ antagonist JTE-013 and the Rho kinase inhibitor Y27632 inhibited IL-4/IL-13–induced increase in STAT6 phosphorylation. We established S1P₂^knockout THP-1 cells using CRISPR-Cas9 gene editing system. PMA-treated S1P₂^knockout THP-1 MΦs showed a lower extent of STAT6 phosphorylation in response to IL-4/IL-13 stimulation than PMA-treated wild-type THP-1 MΦs. S1P₂ knockout markedly attenuated IL-4/IL-13-induced increase in the mRNA expression of the M2 marker arginase 1. These results suggested that S1P₂/Rho kinase pathway is necessary for full activation of STAT6 by IL-4/IL-13 in MΦs. Recently, Th2-type cytokines IL-4/IL-13 have been reported to be important in the pathogenesis of allergic diseases such as bronchial asthma and atopic dermatitis. It is expected that S1P₂ antagonist and Rho kinase inhibitor inhibit Th2-type immune response by IL-4/IL-13, thereby suppressing allergic diseases.