Interaction between Surfactant Protein‐A and Toll‐like Receptor‐4 in Lung

Abstract

Toll‐like receptors (TLR) and surfactant protein (SP)‐A, have been characterized as pathogen‐pattern recognition receptors. Both, TLR4 and SP‐A, have been found to interact in vitro, the in vivo evidence has been lacking. In this study, we investigated the binding between TLR4 and SP‐A in baboon lung by immunoprecipitation/immunoblotting and microwell‐based methods. Basal expression of total TLR4 and SP‐A proteins was quantified in fetal and adult baboon lung tissues by western immunoblotting and ELISA using TLR4 and SP‐A‐specific antibodies. We found that the TLR4 and SP‐A are co‐immunoprecipitated from baboon lung tissues. The binding between the two proteins was also confirmed under in vitro condition. Although the expression of TLR4 and SP‐A, alone, was found to be developmentally regulated, there was no significant difference in the co‐immunoprecipitated TLR4 and SP‐A proteins from fetal or adult baboon lung tissues as detected after immunoprecipitation/cross‐immunoblotting. The interaction between these pathogen‐recognition receptors may play a critical role in pulmonary innate immunity.Research Support: American Lung Association and Presbyterian Health Foundation.