Goose surfactant protein A inhibits the growth of avian pathogenic Escherichia coli via an aggregation-dependent mechanism that decreases motility and increases membrane permeability. (February 2023)

• Record Type: Journal Article
• Authors: Wu, Hanwen; Zhou, Qian; Xiong, Haifeng; Wang, Chenxiao; Cui, Yaqian; Qi, Kezong; Liu, Hongmei
• Is Part Of: Developmental and comparative immunology. Volume 139(2023)
• Publication Date: 2023-02
• Subjects: Goose surfactant proteins A -- Expression -- Agglutination activity -- Bacterial growth and motility -- Membrane permeability; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2022.104592
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: Pulmonary collectins have been reported to bind carbohydrates on pathogens and inhibit infection by agglutination, neutralization, and opsonization. In this study, surfactant protein A (SP-A) was identified from goose lung and characterized at expression- and agglutination-functional levels. The deduced amino acid sequence of goose surfactant protein A (gSP-A) has two characteristic structures: a shorter, collagen-like region and a carbohydrate recognition domain. The latter contains two conserved motifs in its Ca 2+ -binding site: EPN (Glu-Pro-Asn) and WND (Trp-Asn-Asp). Expression analysis using qRT-PCR and fluorescence IHC revealed that gSP-A was highly expressed in the air sac and present in several other tissues, including the lung and trachea. We went on to produce recombinant gSP-A (RgSP-A) using a baculovirus/insect cell system and purified using a Ni 2+ affinity column. A biological activity assay showed that all bacterial strains tested in this study were aggregated by RgSP-A, but only Escherichia coli AE17 ( E. coli AE17, O2) and E. coli AE158 (O78) were susceptible to RgSP-A-mediated growth inhibition at 2–6 h. Moreover, the swarming motility of the two bacterial strains were weakened with increasing RgSP-A concentration, and their membrane permeability was compromised at 3 h, as determined by flow cytometry and laser confocal microscopy. Therefore, RgSP-A is capable of reducing bacterial viability of E. coli O2 and O78 via an aggregation-dependent mechanism which involves decreasing motility and increasing the bacterial membrane permeability. These data will facilitate detailed studies into the role of gSP-A in innate immune defense as well as for development of antibacterial agents. Highlights: GSP-A was found highly expressed in air sac by using qRT-PCR and fluorescence IHC. All bacterial strains tested in this study were aggregated by RgSP-A. RgSP-A inhibits the growth of APEC via an aggregation-dependent mechanism.