To this end, we measured the concentrations of VEGF, PlGF, soluble Flt-1 (sFlt-1), and IL-6 in the SF and/or sera of RA patients and compared them with synovitis severity defined by ultrasonography (US) and therapeutic responses to conventional DMARD (c-DMARD) versus b-DMARD. Here, IL6 is linked to rheumatoid arthritis.