The invention relates to compositions of matter and methods for treating arthritis by modulating Tumor Necrosis Factor Alpha (TNF-alpha) signaling. TNF-alpha plays a key role in the pathogenesis of numerous diseases including rheumatoid and septic arthritis, and other autoimmune and inflammatory diseases. TNF-alpha mediates its effects through receptors that contain a Pre-ligand Assembly Domain (PLAD). The inventors have discovered compounds that interfere with PLAD can block the effects of TNF-alpha in vitro. Treatment of mice with these compounds in vivo ameliorated disease in several models of arthritis. Therefore, the compositions and methods of the current invention may lead to novel arthritis treatments.