1. Department of Microbiology and Immunology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
2. Cancer Vaccine and Immune Cell Therapy Core Laboratory, Chang Gung Immunology Consortium, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan.
3. Graduate Institute of Health Industry Technology, Research Center for Food and Cosmetic Safety, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan City, Taiwan.
4. Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan City, Taiwan.
5. Division of Allergy, Asthma, and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
*These authors contributed equally to this work.
Berberine is an isoquinoline alkaloid isolated from various Chinese herbs that has potential of anti-inflammatory, anti-lipidemic, anti-neoplastic, and anti-diabetic activity. In this study, we evaluated the anti-inflammatory efficacy of berberine on allergic airway inflammation by targeting epithelial cells. Allergic airway inflammation driven by T helper 2 (Th2)-type immunity is characterized by airway hyperresponsiveness, elevated IgE production, and eosinophilic infiltration. For eosinophil recruitment, major chemoattractant CCL11 (eotaxin-1) was secreted by lung epithelial cells. BEAS-2B cells, a human bronchial epithelial cell line, were pre-treated with berberine and then activated by IL-4 plus TNF-α. The viability of BEAS-2B cells was assessed. Expression levels of IL-6 and CCL11 were determined using ELISA and real-time PCR. The signaling pathways of MAP kinases, NF-κB, and STAT6 were analyzed by western blot. Berberine treatment (≤1 μM) didn't significantly affect the viability of BEAS-2B cells with or without IL-4 plus TNF-stimulation. Berberine significantly inhibited the secretion of IL-6 and CCL11 from pro-inflammatory cytokine-activated BEAS-2B cells. NF-κB and MAP kinase pathways were seemingly unaffected in BEAS-2B cells with berberine treatment. Significant reduction of nuclear STAT6 protein expression in activated BEAS-2B cells with berberine treatment was observed. Current study reveals that berberine has inhibitory effect in pro-inflammatory cytokine-activated BEAS-2B cells through reducing IL-6 and CCL11 production, which is possibly modulated by suppressing STAT6 signaling pathway.
Keywords: Berberine, cytokines, asthma, eotaxin, epithelial cell