Understanding Interleukin 6 (IL-6)
What It Is: Interleukin 6 (IL-6) is a cytokine, a type of protein that plays a crucial role in the immune system. It acts as both a pro-inflammatory cytokine and an anti-inflammatory myokine. In humans, IL-6 is encoded by the IL6 gene.
Why It's Important: IL-6 is essential for various bodily functions, including the immune response, inflammation, and the regulation of metabolic, regenerative, and neural processes. It is involved in the body's defense against infections and injuries, and it also plays a role in chronic inflammatory diseases and autoimmune disorders.
Role of IL-6:
Immune Response: IL-6 is secreted by macrophages in response to microbial molecules, triggering an inflammatory response. It helps stimulate the production of acute-phase proteins and neutrophils in the bone marrow.
Inflammation: IL-6 is a key mediator of fever and the acute phase response. It promotes the synthesis of inflammatory proteins and supports the growth of B cells.
Metabolic Functions: IL-6 can cross the blood-brain barrier and influence body temperature and energy mobilization. It is also produced by adipocytes and is linked to higher levels of C-reactive protein (CRP) in obese individuals.
Chronic Diseases: IL-6 is implicated in various chronic diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, and certain types of cancer.
How IL-6 Works:
Production: IL-6 is produced by various cells, including T lymphocytes, B lymphocytes, macrophages, fibroblasts, and endothelial cells.
Circulation: IL-6 is released into the bloodstream and binds to its receptor, IL-6R, on target cells. This binding triggers intracellular signaling pathways that lead to the production of inflammatory proteins.
Clinical Significance:
Diagnostic Marker: Elevated levels of IL-6 can be used as a marker for inflammation and infection. It is also being studied as a potential marker for severe COVID-19 infection.
Therapeutic Target: IL-6 blockade has been approved for the treatment of several autoimmune disorders, including rheumatoid arthritis and neuromyelitis optica spectrum disorder (NMOSD).
Additional Details:
Structure: IL-6 is a small polypeptide with a molecular weight of 19–28 kDa. It consists of 184 amino acid residues and has glycosylation sites and disulfide bonds.
Gene Location: The IL6 gene is located on chromosome 7p and includes 4 introns and 5 exons