Serum amyloid A1 protein (SAA1)

Serum amyloid A1 protein (SAA1) is a highly conserved, major acute-phase protein predominantly synthesized in the liver in response to inflammatory cytokines (notably IL-1β, IL-6, TNF-α), infection, tissue injury, and malignancy[2][5]. It is released into the bloodstream where its levels can increase up to 1,000-fold during acute inflammation. Structurally, SAA1 forms a hexameric cone-shaped assembly, with each subunit adopting a four-helix bundle; its C-terminal tail stabilizes this structure[1][3]. Functionally, SAA1 plays essential roles in modulating the immune response (promoting leukocyte recruitment and polarization), remodeling HDL and influencing lipid metabolism, exerting antibacterial effects, and participating in tissue repair[1][4][5][6]. Chronically elevated SAA1, especially in genetically predisposed individuals, can lead to proteolytic cleavage and misfolding, resulting in amyloid A fibril deposition and systemic AA amyloidosis; this is a serious complication in diseases with persistent inflammatory activity, such as familial Mediterranean fever, rheumatoid arthritis, and chronic infections[4][5][6]. SAA1 serves as a sensitive clinical biomarker for inflammation and disease activity across multiple conditions.

Other names

SAA1Serum amyloid A proteinAcute-phase SAAAmyloid A precursor

Indirect lowering of SAA1 synthesis by anti-inflammatory biologics or corticosteroids (These reduce the cytokines—such as IL-1β, IL-6, TNF-α—that drive SAA1 expression.)[2][5] Colchicine prevents amyloidosis by suppressing inflammation and thus SAA1 overproduction[4]