Developments in the Treatment of Amyloid A Amyloidosis Secondary to Rheumatoid Arthritis

Amyloidosis refers to a heterogeneous group of diseases in which a soluble precursor, misfolded protein, and subsequently aggregates into highly structured protein fibrils with a cross-β-pleated structure. Of these diseases, amyloid A (AA) amyloidosis is a complication of long-standing inflammatory diseases such as rheumatoid arthritis (RA). Treatment of this amyloidosis with RA aims to stop serum AA protein production. Immunosuppressants have reportedly been useful for both RA inflammation and AA amyloidosis. Also, biologics are effective for these specific pathological processes by targeting key players in each inflammation. In addition to the above-mentioned medications, agents both inhibiting AA fibrillogenesis and destabilizing AA fibrils have recently been employed. Phagocytes play important roles in the regression of AA fibrils. Renal involvement is the most common complication in AA amyloidosis. Peritoneal dialysis, hemodialysis, and even renal transplantation are available for patients with end-stage renal disease and AA amyloidosis. This chapter thus discusses current developments in the treatment of AA amyloidosis secondary to RA.