Interleukin 6–soluble interleukin 6 receptor complex (IL-6–sIL-6R complex)

The **interleukin 6–soluble interleukin 6 receptor complex** (IL-6–sIL-6R complex) is a functional heterodimer formed by the cytokine interleukin 6 (IL-6) and the soluble form of its receptor (sIL-6R). This complex enables **IL-6 trans-signaling**, in which cells lacking membrane-bound IL-6R (such as endothelial cells, smooth muscle cells, and certain immune cells) respond to IL-6 via interaction with the ubiquitously expressed signal-transducing receptor gp130[6][2][7]. Binding of IL-6 to sIL-6R allows the complex to associate with gp130, leading to **hexameric complex assembly** (two molecules each of IL-6, sIL-6R, and gp130) and subsequent activation of **downstream signaling pathways** including JAK/STAT and MAPK[1][5][6][7]. IL-6 trans-signaling drives a range of biological responses including inflammation, immune cell recruitment, angiogenesis, and tissue regeneration, and is distinct from classic IL-6 signaling, which requires membrane-bound IL-6R[4][6]. Deregulated IL-6–sIL-6R signaling is implicated in diverse diseases including chronic inflammation, autoimmunity, cancer, and cardiovascular disorders. Several **therapeutics** act by inhibiting the IL-6/sIL-6R interaction or the downstream signaling cascade to treat conditions such as rheumatoid arthritis, cytokine release syndrome, and other inflammatory diseases[2][6]. Pharmacological targeting of this pathway, especially through trans-signaling blockade, represents a validated therapeutic strategy but comes with **safety concerns related to immune suppression** and off-target effects[2][6].

Other names

IL-6/sIL-6R complexInterleukin-6–soluble receptor complexIL-6–trans-signaling complexIL-6:IL-6R complex

Antagonism of IL-6 trans-signaling (by blocking IL-6/sIL-6R interaction with gp130); Inhibition of IL-6 mediated downstream JAK/STAT signaling; Monoclonal antibody neutralization of IL-6 or IL-6 receptor