THE BIOCHEMICAL FEATURES, PHYSIOLOGICAL ASPECTS, AND CLINICAL APPLICATIONS OFSERUM AMYLOID A : A REVIEW

Abstract

Serum amyloid A (SAA) is one of the most abundant acute-phase proteins that exerts a key role in the inflammatory response, and is considered a clinically significant biomarker in many pathologies. Under inflammatory conditions, plasma SAA levels can rise over 1000- fold due to rapid hepatic production, which is largely regulated by interleukin-6 and other pro-inflammatory cytokines. In this review, we will summarize the biochemical properties, physiological functions, and clinical applications of SAA, emphasizing its biological significance in immune regulation, lipid metabolism, and tissue repair, respectively. Structurally, SAA is a small amphipathic protein which associate with high density lipoproteins (HDL) and perform its role in regulating cholesterol transport and modulating inflammatory signaling pathway. Physiologically, SAA plays a role inchemoattraction, and acts as a modulator of cytokine production and in host defense. Clinically, sustained increment of SAA has been associated with chronic inflammatory diseases and is the major precursor protein for AA amyloidosis, and an even more sensitive biomarker for disease activity and prognosis in several somatic illnesses such as infection, autoimmune disease, cardiovascular disorders and malignancies. Recent discoveries suggest that serum amyloid A (SAA) can be more sensitive than C-reactive protein in clinical conditions