IL6R

IL6R Full Name

Interleukin 6 receptor

IL6R Introduction

The Interleukin-6 Receptor (IL6R), also known as CD126, is a transmembrane protein that serves as the specific alpha subunit for the cytokine Interleukin-6 (IL-6). It exists in two primary forms: a membrane-bound receptor (mIL6R) and a soluble receptor (sIL6R). The mIL6R is an 80 kDa type I transmembrane glycoprotein, consisting of an extracellular IL-6 binding domain, a transmembrane region, and a short cytoplasmic tail that lacks intrinsic signaling capability. The sIL6R is generated either by alternative splicing or by proteolytic cleavage (shedding) of the membrane-bound form, mediated by enzymes like ADAM17. This soluble form is crucial for a process known as IL-6 trans-signaling.

Figure 1. Strcuture of Interleukin 6 receptor.

Dysregulation of IL6R expression or function is closely linked to the pathogenesis of numerous human diseases, making it a key therapeutic target. Aberrant IL6R activity is implicated in the development and progression of autoimmune diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, giant cell arteritis, and systemic lupus erythematosus, where excessive IL6 signaling drives chronic inflammation and tissue damage. Additionally, IL6R dysregulation is associated with several cancers, such as multiple myeloma and prostate cancer, as it promotes cell proliferation, survival, and metastasis through sustained activation of oncogenic signaling pathways. Other conditions linked to IL6R dysfunction include Castleman disease, cytokine release syndrome (CRS), and sepsis, highlighting the receptor's role in both inflammatory and neoplastic disorders. Notably, HIV-1 proteins such as Tat and gp120 have been shown to upregulate IL6R expression, contributing to viral pathogenesis.

Given its pivotal role in physiology and pathology, IL6R has become a major focus of translational research and drug development over the past decade. The first approved anti-IL6R therapy, tocilizumab—a humanized monoclonal antibody—binds to both mIL6R and sIL6R, preventing IL6 from associating with its receptor and inhibiting downstream signaling. This therapy is now used worldwide to treat various rheumatic and inflammatory diseases, significantly improving patient outcomes. Ongoing research aims to further elucidate the molecular mechanisms of IL6R regulation, explore its role in additional disease contexts, and develop novel targeted therapies with enhanced specificity and fewer side effects. As our understanding of IL6R deepens, it continues to emerge as a versatile therapeutic target with the potential to transform the treatment of a wide range of chronic inflammatory and neoplastic conditions.

Alternate Names for IL6R

IL6R; interleukin 6 receptor; IL6Q; gp80; CD126; IL6RA; IL6RQ; IL-6RA; IL-6R-1; interleukin-6 receptor subunit alpha; IL-6R 1; CD126 antigen; membrane glycoprotein 80; IL-6 receptor subunit alpha; ALX-0061