Identification of a nanobody specific to human pulmonary surfactant protein A

• Published in: Scientific reports 2017-05, Vol.7 (1), p.1412-12, Article 1412
• Main Authors: He, Xian, Wang, Shan-Mei, Fang Yin, Zhao, Zhao, Meng-Meng, Li, Nan, Yu, Feng, Wang, Liu-Sheng, Hu, Yang, Du, Yu-Kui, Du, Shan-Shan, Li, Yan, Wei, Ya-Ru, Chen, Shan-Shan, He, Jian-Hua, Weng, Dong, Li, Hui-Ping
• Format: Article
• Language: English
• Subjects: 101/28; 13/1; 13/51; 14/19; 38/23; 38/39; 38/44; 42/35; 631/1647/664/2229; 631/250/248; 631/61/350/354; 64/60; 692/4017; 82/80; 82/81; 82/83; Airborne particulates; Animals; Cell Line; Drug delivery; Drug Delivery Systems; Enzyme-linked immunosorbent assay; Female; Hepatocytes; Humanities and Social Sciences; Humans; Kidneys; Libraries; Lung - metabolism; Lungs; Mice, Inbred BALB C; Mice, Nude; multidisciplinary; Nanobodies; pH effects; Phages; Pulmonary Surfactant-Associated Protein A - immunology; Pulmonary Surfactant-Associated Protein A - pharmacology; Rats; Recombinant Proteins; Science; Science (multidisciplinary); Single-Domain Antibodies - pharmacology; Surfactant protein A; Surfactants; Tissue Distribution; Tissues; Toxicity
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-01456-2

Nanobody (Nb) is a promising vector for targeted drug delivery. This study aims to identify an Nb that can specifically target the lung by binding human pulmonary surfactant protein A (SP-A). Human lung frozen tissue sections were used for 3 rounds of biospanning of our previously constructed Nb library for rat SP-A to establish a sub-library of Nb, which specifically bound human lung tissues. Phage-ELISA was performed to screen the sub-library to identify Nb4, which specifically bound human SP-A. The binding affinity Kd of Nb4 to recombinant human SP-A was 7.48 × 10 −7 M. Nb4 (19 kDa) was stable at 30 °C–37 °C and pH 7.0–7.6 and specifically bound the SP-A in human lung tissue homogenates, human lung A549 cells, and human lung tissues, whereas didn’t react with human liver L-02 cells, kidney 293T cells, and human tissues from organs other than the lung. Nb4 accumulated in the lung of nude mice 5 minutes after a tail vein injection of Nb4 and was excreted 3 hours. Short-term exposure (one month) to Nb4 didn’t cause apparent liver and kidney toxicity in rats, whereas 3-month exposure resulted in mild liver and kidney injuries. Nb4 may be a promising vector to specifically deliver drugs to the lung.