The immunomodulatory activity of protein S protects against allergic airway inflammation

Background: Protein S (PS) is a vitamin K-dependent plasma protein with anticoagulant, anti-inflammatory and anti-apoptotic properties. PS regulates the inflammatory response and apoptosis by binding and activating the TAM family of receptor tyrosine kinases. PS can protect against LPS-induced acute lung injury by directly inhibiting the local expression of inflammatory cytokines from several inflammatory cells. Bronchial asthma is characterized by airway inflammation and remodeling with a decline of lung function. The role of PS in bronchial asthma is unknown. Object: The aim of this study was to clarify the role of PS in bronchial asthma. Method: Bronchial asthma was induced in wild type (WT) C57BL/6 and human PS transgenic mice (PS) by sensitization and challenge with ovalbumin. Airway hyperresponsiveness, the concentration of inflammatory cytokines, IgE and the number of inflammatory cells were measured and compared between WT and PS transgenic mice. Mice treated with saline were used as controls. Result: Airway hyperresponsiveness, the number of eosinophils and the concentration of inflammatory cytokines were significantly reduced in PS transgenic mice sensitized and challenged with ovalbumin compared with their WT counterparts and control mice. Conclusion: The results of this study suggest the protective role of PS in allergic airway inflammation.