PT  - JOURNAL ARTICLE
AU  - Shanjana Awasthi
AU  - Kevin Brown
AU  - Catherine King
AU  - Vibhudutta Awasthi
AU  - Rajkumar Bondugula
TI  - A TLR4-interacting Surfactant Protein-A-derived Peptide Suppresses TNF-α release from Mouse JAWS II Dendritic Cells.
AID  - 10.1124/jpet.110.173765
DP  - 2010 Jan 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - jpet.110.173765
4099  - http://jpet.aspetjournals.org/content/early/2010/12/15/jpet.110.173765.short
4100  - http://jpet.aspetjournals.org/content/early/2010/12/15/jpet.110.173765.full
AB  - Surfactant protein-A (SP-A) and Toll-like receptor-4 (TLR4) proteins are recognized as pathogen-recognition receptors. An exaggerated activation of TLR4 induces inflammatory response, while SP-A protein downregulates inflammation. We hypothesized that SP-A-TLR4 interaction may lead to inhibition of inflammation. In this study, we investigated interaction between native baboon lung SP-A, and baboon- and human-TLR4-MD2 proteins by co-immunoprecipitation/immunoblotting and microwell-based methods. The interaction between SP-A and TLR4-MD2 proteins was then analyzed using a bioinformatics approach. In the in silico model of SP-A-TLR4-MD2 complex, we identified potential binding regions and amino acids at the interface of SP-A-TLR4. Using this information, we synthesized a library of human-SP-A-derived peptides that contained interacting amino acids. Next, we tested if the TLR4-interacting SP-A peptides will suppress inflammatory cytokines. The peptides were screened for any changes in the TNF-α response against lipopolysaccharide (LPS) stimuli in mouse JAWS II dendritic cell line. Different approaches employed here in this study suggested binding between SP-A and TLR4-MD2 proteins. In cells pre-treated with peptides, 3 out of 7 peptides increased TNF-α production against LPS. However, two of these peptides (SPA4: GDFRYSDGTPVNYTNWYRGE and SPA5: YVGLTEGPSPGDFRYSDFTP) decreased the TNF-α production in LPS-challenged JAWS II dendritic cells; SPA4 peptide showed more pronounced inhibitory effect than SPA5 peptide. In conclusion, we identify a human-SP-A-derived peptide (SPA4 peptide) that interacts with TLR4-MD2 protein and inhibits the LPS-stimulated release of TNF-α in JAWS II dendritic cells.