Objective  To explore the role of macrophage-stimulating protein ( MSP) and receptor tyrosine kinase RON in the airway inflammation of chronic obstructive pulmonary disease( COPD) , and investigate its possible mechanism.
Methods  The rat COPDmodel was established by exposing the rats to cigarette smoke daily for three months. Rat alveolar macrophages ( AMs) were isolated in vivo and cultured,and then challenged with different concentrations of MSP for 24 hours. The concentrations of MSP in broncho-alveolar lavage fluid ( BALF) and serum, and the levels of IL-1β, TNF-α, IL-8, and IL-10 in the supernatants were measured by ELISA. The expression of RONmRNA in lung tissue was assessed by reverse transcription-polymerase chain reaction. The levels of RON protein in the lung tissue and AMs cultured in vitro were observed by immunohistochemistry. The activity of superoxide dismutase ( SOD) and malondialdehyde ( MDA) content in the culture solution were measured with chromatometry method.
Results  Compared with the control group, the concentrations of MSP in serum and BALF of the COPD rats were significantly higher ( P  lt;0. 01) . The levels of RONmRNA and RON protein in the COPD rats were also upregulated significantly ( P  lt; 0. 01) . MSP evoked the AMs isolated from the normal and COPD rats to generate more content of MDA and caused a reduction in activity of SOD. In addition, MSP stimulated TNF-α, IL-8, IL-1βand IL-10 release fromAMs of the normal and COPD rats dose-dependently. The levels of TNF-α, IL-8, and IL-1βwere higher, while the level of IL-10 and the SOD activity were lower in AMs of the COPD group than those of the control group in the same dose of MSP ( P  lt;0. 01) . The more significant increase in the levels of TNF-α, IL-8, IL-1β, and the more notable decrease in the activity of SOD was found in the COPD group compared with the control group. But the degree of increasing MDA and IL-10 in the AMs of the COPD group was lower than that in the control group. Linear correlation analysis showed that the MSP concentration and the RON protein level in the COPD rats were positively associated with the total cell
counts and AM counts in BALF, and were related to the indexes for pulmonary emphysema.
Conclusions  There is a close correlation between the MSP and receptor tyrosine kinase RON with the airway inflammation of COPD. The mechanism might be that MSP promote the macrophages release inflammatory factors and increase the production of oxygen free radicals.

Citation： WANG Tao,CHENXiaoju,ZHANGWenbo.. The Role of Macrophage-Stimulating Protein and Receptor Tyrosine Kinase RON in Airway Inflammation of COPD. Chinese Journal of Respiratory and Critical Care Medicine, 2012, 11(5): 437-443. doi: Copy