Involvement of ERK Signaling Pathway in the Therapeutic Effect of Hanchuan Zupa Granule in Ovalbumin-Induced Asthma in Rats

Abstract

Background: Hanchuan zupa granule (H granule) is a traditional prescription in treating cough and asthma in China. Nevertheless, the underlying mechanism by which H granule improve asthma is unclear. Evidences have demonstrated the involvement of extracellular-signal-regulated kinase (ERK) pathway in airway remodeling. Therefore, this study aimed to investigate whether ERK pathway involves the underlying mechanism of H granule on asthma. Methods: Fourty male Sprague-Dawley rats were randomly assigned into control, asthma, H granule and dexamethasone (positive control) groups. Asthma rat model was established by OVA (ovalbumin) sensitization and challenge. Lung histopathology was assessed by hematoxylin-eosin staining, followed by the measurement of bronchial basement membrane perimeter (Pbm), total bronchial wall area (WAt), inner wall area (WAi) and smooth muscle area (WAm). Levels of interleukin (IL)-13, IL-1β and IL-17 in bronchoalveolar lavage fluid (BALF), and serum immunoglobulin E (lgE) level were examined using ELISA (enzyme-linked immunosorbent assay). Western blotting and immumohistochemical staining were conducted to explore the expression of members in ERK pathway. Results: Structure of bronchus in asthma model changed, reflecting by increased WAt/Pbm, WAi/Pbm and WAm/Pbm, and such changes were reversed after H granule treatment (p < 0.05). Besides, levels of inflammatory cytokines IL-13, IL-1β and IL-17 in BALF and serum lgE were up-regulated in asthma model, while down-regulated after H granule treatment (p < 0.05). Additionally, ERK pathway was activated in asthma model, reflecting by up-regulated expression of C-FOS (Fos Proto-Oncogene, AP-1 Transcription Factor Subunit), C-JUN (Jun Proto-Oncogene, AP-1 Transcription Factor Subunit), p-ERK (Phosphorylated ERK), MEK1 ( Mitogen-Activated Protein Kinase Kinase 1), MMP9 (Matrix Metallopeptidase 9), TIMP1 (TIMP Metallopeptidase Inhibitor 1), RAF1 (Raf-1 Proto-Oncogene, Serine/Threonine Kinase) and RASA1 (RAS P21 Protein Activator 1), and the elevated expression for these genes were significantly down-regulated after the H granule treatment (p < 0.05). Conclusions: The therapeutical effect of H granule on asthma probably by regulating airway remodeling through ERK pathway and inhibiting inflammation.