Effect of the Chinese herb extract osthol on IL-4-induced eotaxin expression in BEAS-2B cells.
BACKGROUND
Asthma is an allergic inflammatory disease of the airways. The interaction between bronchial epithelial cells and eosinophils is an important feature of an asthma attack. Eotaxin, an eosinophil-specific C-C chemokine, is a potent chemoattractant involved in the mobilization of eosinophils into the airway after allergic stimulation. Cnidii monnieri fructus, the dried fruit of Cnidium monnieri Cusson, has been used as an antipruritogenic agent in ancient China. OsthoL is the major component of Cnidii monnieri fructus extract. We investigated the ability of osthol to regulate cytokine-induced eotaxin expression in the human bronchial epithelial cell line BEAS-2B.


METHODS
BEAS-2B cells were pretreated with osthol at different concentrations (0.1-10 microM), and then stimulated with interleukin (IL)-4 alone, or in combination with tumor necrosis factor (TNF)-alpha. Eotaxin levels were determined by real-time reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. STAT6 (signal transducer and activator of transcription 6) and MAPK (mitogen-activated protein kinase) expressions were evaluated by Western blotting, to detect possible intracellular signal transduction.


RESULTS
IL-4 and TNF-alpha significantly induced eotaxin expression in BEAS-2B cells. Expression of eotaxin was suppressed by osthol (0.1-10 microM) in a dose-dependent manner. Osthol did not suppress IL-4-induced p38, ERK or JNK expression. Osthol did suppress IL-4-induced STAT6 in a dose-dependent manner.


CONCLUSIONS
Osthol suppressed IL-4-induced eotaxin in BEAS-2B cells via inhibition of STAT6 expression. This data suggest that osthol might have potential for treating allergic airway inflammation.
Chiu
Pu-Rong
PR
Department of Pediatrics, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
Lee
Wei-Te
WT
Chu
Yu-Te
YT
Lee
Min-Sheng
MS
Jong
Yuh-Jyh
YJ
Hung
Chih-Hsing
CH
D001980:Bronchi / Q000166:cytology / Q000187:drug effects*; D002460:Cell Line; D019742:Chemokines, CC / Q000032:analysis*; D003374:Coumarins / Q000494:pharmacology*; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology
D019742:Chemokines, CC; D003374:Coumarins; D004365:Drugs, Chinese Herbal; D015847:Interleukin-4; C046627:osthol