title: A TLR4-interacting SPA4 peptide inhibits LPS-induced lung inflammation.
abstract: The interaction between surfactant protein-A (SP-A) and TLR4 is important for host defense. We have recently identified an SPA4 peptide region from the interface of SP-A-TLR4 complex. Here, we studied the involvement of the SPA4 peptide region in SP-A-TLR4 interaction using a two-hybrid system, and biological effects of SPA4 peptide in cell systems and a mouse model. HEK293 cells were transfected with plasmid DNAs encoding SP-A or a SP-A-mutant lacking SPA4 peptide region and TLR4. Luciferase activity was measured as the end-point of SP-A-TLR4 interaction. NF-κB activity was also assessed simultaneously. Next, the dendritic cells or mice were challenged with Escherichia coli-derived LPS and treated with SPA4 peptide. Endotoxic shock-like symptoms and inflammatory parameters (TNF-α, NF-κB, leukocyte influx) were assessed. Our results reveal that the SPA4 peptide region contributes to the SP-A-TLR4 interaction and inhibits the LPS-induced NF-κB activity and TNF-α. We also observed that the SPA4 peptide inhibits LPS-induced expression of TNF-α, nuclear localization of NF-κB-p65 and cell influx, and alleviates the endotoxic shock-like symptoms in a mouse model. Our results suggest that the anti-inflammatory activity of the SPA4 peptide through its binding to TLR4 can be of therapeutic benefit.
authors.affiliation: 1Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
authors.forename: Vijay
authors.initials: V
authors.lastname: Ramani
authors.forename: Rakhesh
authors.initials: R
authors.lastname: Madhusoodhanan
authors.forename: Stanley
authors.initials: S
authors.lastname: Kosanke
authors.forename: Shanjana
authors.initials: S
authors.lastname: Awasthi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism*; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D008070:Lipopolysaccharides / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D011014:Pneumonia / Q000276:immunology*; D011485:Protein Binding / Q000235:genetics; D060066:Protein Interaction Maps; D037662:Pulmonary Surfactant-Associated Protein A / Q000235:genetics / Q000378:metabolism*; D012772:Shock, Septic / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*; D019076:Transgenes / Q000235:genetics
chemical_list: D008070:Lipopolysaccharides; D010446:Peptide Fragments; D037662:Pulmonary Surfactant-Associated Protein A; C000589642:SPA4 peptide, human; D051197:Toll-Like Receptor 4
keywords: Inflammation; Toll-like receptor-4; host defense; protein–protein interaction; surfactant protein-A