Extrahepatic expression of plasma protein genes during inflammation

The body's protective responses to infection, wounding, trauma, and malignancy include the acute-phase reaction, which is modulated by various cytokines and their cellular receptors. During the acute-phase reaction, levels of specific proteins synthesized by the liver increase in the plasma. Little information is available about the extrahepatic synthesis of plasma proteins during the acute-phase reaction. The study described here analyzes the tissue-specific expression of genes encoding the plasma proteins albumin (ALB), alpha 1-antitrypsin (AAT), transferrin (TF), haptoglobin (HP), ceruloplasmin (CP), serum amyloid A (SAA), alpha 1-acid glycoprotein (AGP) and alpha 2-HS-glycoprotein (AHSG) during the acute-phase reaction in C57B1 mice. The acute-phase reaction was induced by intraperitoneal injections of bacterial lipopolysaccharide (LPS). During the acute-phase reaction, genes encoding CP, SAA, AGP, and HP demonstrate unique extrahepatic tissue specific patterns of expression in kidney, spleen, thymus, heart, brain, lung, testis, and epididymis. Different temporal patterns of HP gene expression also were observed in lung and thymus after induction by LPS. The function of extrahepatic synthesis of plasma proteins is not yet understood; however, a local provision of specific plasma proteins in mammalian tissues may offer the host a source of functionally important proteins during periods of stress.