Expression of functional leukotriene B 4 receptors on human airway smooth muscle cells

• Published in: Journal of allergy and clinical immunology Vol. 124; no. 1; pp. 59 - 65.e3
• Main Authors: Watanabe, Satoko, Yamasaki, Akira, Hashimoto, Kiyoshi, Shigeoka, Yasushi, Chikumi, Hiroki, Hasegawa, Yasuyuki, Sumikawa, Takashi, Takata, Miyako, Okazaki, Ryota, Watanabe, Masanari, Yokogawa, Tsuyoshi, Yamamura, Miki, Hayabuchi, Tatsuya, Gerthoffer, William T., Halayko, Andrew J., Shimizu, Eiji
• Format: Journal Article
• Language: English
• Published: Mosby, Inc 01.07.2009
• Subjects: airway remodeling; airway smooth muscle cells; Asthma; BLT; LTB 4; EGF; JNK; airway remodeling; airway smooth muscle cells; hTERT-ASM; BLT; AHR; MAPK; cysLT; Asthma; DMEM; MEK; LTB 4; GPCR; ASM
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2009.03.024

Leukotriene B 4 (LTB 4) increases in induced sputum and exhaled breath condensate in people with asthma. Furthermore, the T H2-type immune response and airway hyperresponsiveness induced by ovalbumin sensitization is markedly suppressed in LTB 4 receptor (BLT) 1 null mice. These studies suggest that LTB 4 may contribute to asthma pathophysiology. However, the direct effects of LTB 4 on human airway smooth muscle (ASM) have not been studied. We sought to determine the expression of LTB 4 receptors on human ASM and its functional role in mediating responses of human ASM cells, and the effect of LTB 4 on these cells. Immunohistochemistry, RT-PCR, Western blotting, and flow cytometry were used to determine the expression of LTB 4 receptors. To determine the effect of LTB 4 on human ASM cells, cell proliferation was assessed by counting cells, and chemokinesis was assessed by gold particle phagokinesis assay. We confirmed expression of both BLT1 and BLT2 in human ASM cells in bronchial tissue and in cell culture. LTB 4 markedly induced cyclin D1 expression, proliferation, and chemokinesis of human ASM cells. LTB 4 also induced phosphorylation of both p42/p44 mitogen-activated protein kinase (MAPK) and downstream PI3 kinase effector, Akt1. However, we observed no induction of c-Jun N-terminal kinase or p38 MAPK. Notably, LTB 4-induced migration and proliferation of ASM cells were inhibited by the BLT1 specific antagonist, U75302, and by inhibitors of p42/p44 MAPK phosphorylation (U1026), and PI3 kinase (LY294002). These observations are the first to suggest a role for a LTB 4-BLT1 signaling axis in ASM responses that may contribute to the pathogenesis of airway remodeling in asthma.