IL6ST and rheumatoid arthritis: For instance, tocilizumab, which targets IL6 signaling, has been approved for the treatment of rheumatoid arthritis (RA).6 In the blood plasma, a soluble fraction of the IL6 receptor (sIL6R) forms with soluble gp130 (sgp130/sIL6ST) and IL6 an inhibitory complex.7 As such, plasma sIL6R, which is acting as a decoy receptor, negatively regulates IL6 signaling.