[Biologics-Induced Kidney Injury -with Special Attention to Anti-Rheumatic Drugs -].

A variety of anti-rheumatic drugs including biologics are currently used to treat rheumatoid arthritis (RA). These drugs, as well as RA itself, can cause kidney injury. RA may trigger mesangial proliferative glomeru- lonephritis (MesPGN), membranous nephropathy (N), thin basement membrane disease, and renal amyloi- dosis. As for anti-rheumatic drugs, non-steroidal anti-inflammatory drugs (NSAID) increase serum Cr lev- els due to a reduction of glomerular circulation, particularly in the presence of dehydration. Among disease- modifying anti-rheumatic drugs (DMARD), methotrexate as an anchor drug for RA rarely causes tubular ob- struction as a result of its crystallization, and bucillamine occasionally elicits IN. Calcineurin inhibitors induce vasoconstriction of the afferent arteries. Recently developed anti-rheumatic drugs, biologics, include biological inhibitors of TNF-a, IL6, and CD80/26. These can generally induce the remission of RA, while they have been reported to albeit uncom- monly trigger autoimmune renal disorders (AIRD). A recent meta-analysis identified a total of 29 cases with biologics-induced AIRD, 62% of who manifested AIRD within 12 months after treatment with biologics. AIRD cases were classified into 3 different groups: isolated autoimmune renal disorders (IARD, n =13), glo- merulonephritis with systemic vasculitis (GNSV, n= 12), and glomerulonephritis with lupus-like syndrome (GNLS, n=4). The IARD cases had 4 MesPGN, 4 MN, and 2 crescentic GN, while the GNSV cases had 8 crescentic GN and 3 purpura GN, and the GNLS cases had all MesPGN. To detect these renal disorders early in RA patients, urinalysis and serum Cr measurement should be peri- odically performed. New urinary biomarkers (L-FABP and Ngal) may be more sensitive for kidney injury. Notably, in RA patients receiving biologics, ANA, anti-dsDNA, and ANCA should also be tested at the base- line and regular intervals. [Review].