IL-6 receptor

Class

anti-IL-6R monoclonal antibody (sarilumab drug-product formulation, dev code SAR153191)

Pathway

Blocks IL-6 signaling via membrane-bound and soluble IL-6R (JAK/STAT3 pathway)

Notes

original target text: IL-6 receptor (IL-6R)

Interleukin-6 (IL-6) is a cytokine, a small signaling protein released by immune and other cells, that coordinates inflammation, acute-phase protein production in the liver, and aspects of blood cell development. It acts by binding the IL-6 receptor (IL-6R), which exists both anchored on cell membranes and in a soluble, circulating form. Receptor engagement triggers an intracellular relay called the JAK/STAT3 pathway, which switches on genes driving inflammatory and metabolic responses. In chronic inflammatory diseases, sustained IL-6 signaling contributes to joint damage, systemic symptoms such as fatigue and fever, and abnormal laboratory markers of inflammation. Monoclonal antibodies directed against IL-6R bind both the membrane-bound and soluble forms of the receptor, preventing IL-6 from engaging either and thereby interrupting downstream JAK/STAT3 activation regardless of where IL-6 is presented. This dual-form blockade is a deliberate design choice, since soluble IL-6R can still transmit signals to cells that lack the membrane receptor, a process called trans-signaling; antibodies that ignored the soluble receptor would leave this route open. Blocking IL-6R broadly dampens inflammatory cascades relevant to autoimmune and inflammatory conditions, and also to acute states of excessive immune activation, making this mechanism relevant across a range of inflammatory disease contexts.