Reduced MBD2 expression enhances airway inflammation in bronchial epithelium in COPD

Abstract

Zhilin Zeng,1,2 Miao Li,1 Jinkun Chen,3 Qinghai Li,1 Qin Ning,2 Jianping Zhao,1 Yongjian Xu,1 Jungang Xie,1 Jun Yu4 1Department of Respiratory and Critical Care Medicine, National Clinical Research Center of Respiratory Disease, 2Department of Infectious Disease, Institute of Infectious Disease, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People’s Republic of China; 3Acadia Junior High School, Winnipeg, MB, Canada; 4Department of Thoracic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People’s Republic of China Background: Chronic obstructive pulmonary disease (COPD) is a common inflammatory lung disease characterized by inflammatory cells activation and production of inflammatory mediators. Methyl-CpG-binding domain protein 2 (MBD2) plays an important role in diverse immunological disorders by regulating immune cell functions, such as differentiation and mediator secretion. However, the role of MBD2 in COPD remains unknown.Methods: MBD2 protein expression in lung tissues of patients with COPD and cigarette smoke (CS)-exposed mice were evaluated by Western blot and immunohistochemistry. The role of MBD2 in cigarette smoke extract (CSE)-induction of inflammatory mediator expression in the human bronchial epithelial (HBE) cell line was assessed by silencing MBD2 expression in vitro. The involvement of signaling pathways in mediation of inflammation was tested with signaling inhibitors.Results: Compared with controls, MBD2 expression was distinctly reduced in the bronchial epithelium of both patients with COPD and CS-exposed mice. Moreover, MBD2 expression was decreased in HBE after CSE stimulation in vitro. Moreover, MBD2 knockdown enhanced interleukin (IL)-6 and IL-8 expression in HBE in the presence and absence of CSE treatment by the ERK signaling pathway.Conclusion: MBD2 protein expression was reduced in the airway epithelium of COPD. In HBE, this reduced expression was associated with increased levels of IL-6 and IL-8 mediated by the ERK pathway. These results suggest that MBD2 could contribute to chronic airway inflammation in COPD. Keywords: chronic obstructive pulmonary disease, methyl-CpG-binding domain protein 2, airway inflammation

Keywords

• Chronic obstructive pulmonary disease
• Methyl-CpG-binding domain protein 2
• Airway inflammation