Pattern recognition by pentraxins

Pentraxins are a family of evolutionarily conserved pattern-recognition proteins that are made up of five identical subunits. Based on the primary structure of the subunit, the pentraxins are divided into two groups: short pentraxins and long pentraxins. C-reactive protein (CRP) and serum amyloid P-component (SAP) are the two short pentraxins. The prototype protein of the long pentraxin group is pentraxin 3 (PTX3). CRP and SAP are produced primarily in the liver while PTX3 is produced in a variery oftissues during inflammation. The main functions of short pentraxins are to recognize a variery of pathogenic agents and then to either eliminate them or neutralize their harmful effects by utilizing the complement pathways and macrophages in the host. CRP binds to modified low-densiry lipoproteins, bacterial polysaccharides, apoptotic cells, and nuclear materials. By virtue of these recognition functions, CRP participates in the resolution ofcardiovascular, infectious, and autoimmune diseases. SAP recognizes carbohydrates, nuclear substances, and amyloid fibrils and thus participates in the resolution of infectious diseases, autoimmuniry, and amyloidosis. PTX3 interacts with several ligands, including growth factors, extracellular matrix component and selected pathogens, playing a role in complement activation and facilitating pathogen recognition by phagoeytes. In addition, data in gene-targeted mice show that PTX3 is essential in female fertiliry, participating in the assembly of the cumulus oophorus extracellular matrix. PTX3 is therefore a nonredundant component ofthe humoral arm of innate immuniry as well as a tuner of inflammation. Thus, in conjunction with the other components ofinnate immuniry, the pentraxins use their pattern-recognition properry for the benefit of the host.