CCL2 and rheumatoid arthritis: Although a first randomized controlled trial from 2006 could not show a detectable clinical benefit for CCL2 antibody therapy in RA (Haringman et al., 2006), targeting CCL2 is still being extensively discussed as a novel RA treatment approach (Moadab et al., 2021; Zhang et al., 2015; Chen et al., 2017).