CREB regulates TNF-α-induced GM-CSF secretion via p38 MAPK in human lung fibroblasts

• Published in: Allergology international Vol. 65; no. 4; pp. 406 - 413
• Main Authors: Koga, Yasuhiko, Hisada, Takeshi, Ishizuka, Tamotsu, Utsugi, Mitsuyoshi, Ono, Akihiro, Yatomi, Masakiyo, Kamide, Yosuke, Aoki-Saito, Haruka, Tsurumaki, Hiroaki, Dobashi, Kunio, Yamada, Masanobu
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.10.2016; Elsevier
• Subjects: Asthma; cAMP; Cell Line; Cells, Cultured; CREB; Cyclic AMP - metabolism; Cyclic AMP Response Element-Binding Protein - genetics; Cyclic AMP Response Element-Binding Protein - metabolism; Fibroblasts - drug effects; Fibroblasts - metabolism; Gene Expression; Gene Knockdown Techniques; GM-CSF; Granulocyte-Macrophage Colony-Stimulating Factor - genetics; Granulocyte-Macrophage Colony-Stimulating Factor - secretion; Humans; Lung - metabolism; p38 MAPK; p38 Mitogen-Activated Protein Kinases - metabolism; Phosphorylation; RNA, Messenger - genetics; RNA, Messenger - metabolism; Tumor Necrosis Factor-alpha - metabolism; Tumor Necrosis Factor-alpha - pharmacology; BEC; DMSO; HFL-1; JNK; PKA; PKC; siRNA; cAMP; MAPK; IL-8; p38 MAPK; Asthma; PI3-K; CREB; TNF-α; GM-CSF; ASMC; RT-qPCR; GAPDH; COPD; PDE-4; ERK; AHLF; ELISA
• ISSN: 1323-8930; 1440-1592
• DOI: 10.1016/j.alit.2016.03.006

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine that mediates eosinophilic differentiation, migration and survival, causing respiratory tract inflammation. GM-CSF is also known to be secreted from respiratory tract structural cells. However, the mechanisms of GM-CSF secretion have not been well established. Human fetal lung fibroblasts and human primary asthmatic lung fibroblasts were used for the study of tumor necrosis factor alpha (TNF-α)-induced GM-CSF secretion. GM-CSF secretion and mRNA expression were measured by enzyme-linked immunosorbent assay and quantitative real-time reverse transcription polymerase chain reaction, respectively. Knockdown of cAMP response element-binding protein (CREB) in fibroblasts was carried out by using specific small interfering RNAs of CREB. Among respiratory tract structural cells, pulmonary fibroblasts exhibited increased GM-CSF secretion and mRNA expression after stimulation with TNF-α in a concentration-dependent manner. Moreover, a p38 mitogen-activated protein kinase (MAPK) inhibitor controlled TNF-α-induced GM-CSF secretion, and roflumilast and rolipram, inhibitors of phosphodiesterase-4, suppressed TNF-α-induced GM-CSF secretion. Consistent with this, forskolin also completely blocked GM-CSF secretion, and similar results were observed in response to cAMP treatment, suggesting that cAMP signaling suppressed TNF-α-induced GM-CSF secretion in human lung fibroblasts. Furthermore, CREB was phosphorylated through p38 MAPK but not cAMP signaling after TNF-α stimulation, and GM-CSF secretion was inhibited by CREB knockdown. Finally, these effects were also demonstrated in human primary lung fibroblasts in a patient with asthma. CREB signaled independent of cAMP signaling and was phosphorylated by p38 MAPK following TNF-α stimulation, playing a critical role in GM-CSF secretion in human lung fibroblasts.