| First Author | Zhou H | Year | 2017 |
| Journal | J Immunol | Volume | 199 |
| Issue | 3 | Pages | 1105-1112 |
| PubMed ID | 28674180 | Mgi Jnum | J:250961 |
| Mgi Id | MGI:6099734 | Doi | 10.4049/jimmunol.1700470 |
| Citation | Zhou H, et al. (2017) Suppression of Lipopolysaccharide-Induced Inflammatory Response by Fragments from Serum Amyloid A. J Immunol 199(3):1105-1112 |
| abstractText | Serum amyloid A (SAA) is known as an acute-phase protein and a biomarker for inflammatory diseases. Published studies have shown that SAA possesses proinflammatory cytokine-like activity and is chemotactic for phagocytes, but the structural basis for these activities remains unidentified. In this article, we report that truncated SAA1 proteins lacking N- and C-terminal sequences exhibit reduced proinflammatory activity and strongly suppress LPS-induced expression of IL-1beta, IL-6, and TNF-alpha in macrophages. A truncated SAA1 containing aa 11-58 was examined further and found to facilitate p38 MAPK phosphorylation while reducing LPS-stimulated phosphorylation of ERK and JNK. In LPS-challenged mice, aa 11-58 reduced the severity of acute lung injury, with significantly less neutrophil infiltration in the lungs and attenuated pulmonary expression of IL-1beta, IL-6, and TNF-alpha. Coadministration of aa 11-58 markedly improved mouse survival in response to a lethal dose of LPS. A potent induction of IL-10 was observed in a TLR2-dependent, but TLR4-independent, manner in macrophages stimulated with aa 11-58. However, the aa 11-58 fragment of SAA1 was unable to induce chemotaxis or calcium flux through formyl peptide receptor 2. These results indicate that the N- and C-terminal sequences contain structural determinants for the proinflammatory and chemotactic activities of SAA1, and their removal switches SAA1 to an anti-inflammatory role. Given that proteolytic processing of SAA is associated with the pathological changes in several diseases, including secondary amyloidosis, our findings may shed light on the structure-function relationship of SAA1 with respect to its role in inflammation. |
