Therapeutic Strategies in Amyloid A Amyloidosis Secondary to Rheumatoid Arthritis

Amyloidosis is a disorder of protein conformation and metabolism that results in the depo‐ sition of insoluble amyloid fibrils in tissues, which causes organ dysfunction; systemic amy‐ loidosis is characterized by failure of multiple organs and the presence of amyloid precursor protein in the serum [1-3]. Reactive amyloid A (AA) amyloidosis is one of the most severe complications of several chronic disorders, particularly rheumatoid arthritis (RA) [4], and indeed, most patients with reactive AA amyloidosis have an underlying rheumatic disease. An extra-articular complication of RA, AA amyloidosis is a serious, potentially life-threaten‐ ing disorder caused by deposition in organs of AA amyloid fibrils, which derive from the circulatory acute-phase reactant, serum amyloid A protein (SAA) [5]. AA amyloidosis sec‐ ondary to RA is thus one of the intractable conditions found in patients with collagen vascu‐ lar diseases and is an uncommon yet important complication of RA [6]. However, the actual pathological mechanisms that are responsible for the relationship between SAA and AA amyloidosis have not been fully elucidated.