Characterization of rat serum amyloid A4 (SAA4): a novel member of the SAA superfamily.

The serum amyloid A (SAA) family of proteins is encoded by multiple genes, which display allelic variation and a high degree of homology in mammals. The SAA1/2 genes code for non-glycosylated acute-phase SAA1/2 proteins, that may increase up to 1000-fold during inflammation. The SAA4 gene, well characterized in humans (hSAA4) and mice (mSaa4) codes for a SAA4 protein that is glycosylated only in humans.

Expression of serum amyloid A transcripts in human bone tissues, differentiated osteoblast-like stem cells and human osteosarcoma cell lines.

Although the liver is the primary site of cytokine-mediated expression of acute-phase serum amyloid A (SAA) protein, extrahepatic production has also been reported. Besides its role in amyloidosis and lipid homeostasis during the acute-phase, SAA has recently been assumed to contribute to bone and cartilage destruction. However, expression of SAA in human osteogenic tissue has not been studied.

Expression of serum amyloid A transcripts in human trophoblast and fetal-derived trophoblast-like choriocarcinoma cells.

The placenta comprises a highly specialized trophoblast layer, which arises from the embryo and differentiates during embryonic development to perform specialized functions, e.g., synthesis of pregnancy-associated hormones, growth factors and cytokines.

2-chlorohexadecanal derived from hypochlorite-modified high-density lipoprotein-associated plasmalogen is a natural inhibitor of endothelial nitric oxide biosynthesis.

Objective: Myeloperoxidase, a heme enzyme that is present and active in human atherosclerotic lesions, provides a source for the generation of proinflammatory chlorinated reactants contributing to endothelial dysfunction. Modification of high-density lipoprotein (HDL) by hypochlorous acid/hypochlorite (HOCl/OCl-) [correction]-generated in vivo by the myeloperoxidase-hydrogen peroxide-chloride system of activated phagocytes-forms a proatherogenic lipoprotein particle that binds to and is internalized by endothelial cells.

Methods And Results: Here we show that HDL, modified with physiologically relevant HOCl concentrations, attenuates the expression and activity of vasculoprotective endothelial nitric oxide synthase.