Interleukin-8 (IL-8), also known as CXCL8, is a small protein produced by various cells throughout the body. It functions as a signaling molecule within the immune system, playing a role in the body’s response to infection and injury. Understanding IL-8 provides insight into how the immune system communicates and coordinates its defense mechanisms.
Understanding IL-8: A Key Immune Messenger
IL-8 is categorized as a cytokine, and more specifically, it is a chemokine, belonging to the CXC family. Chemokines guide cell movement, a process called chemotaxis, directing immune cells to specific locations where they are needed.
Various cells produce IL-8, including macrophages, endothelial cells, epithelial cells, and fibroblasts. Its production is triggered by inflammatory signals from infections or tissue injury. IL-8 acts as a “call for help,” initiating a cascade of events that brings other immune cells into action.
IL-8’s Role in Inflammation and Immune Response
The primary function of IL-8 is to orchestrate the inflammatory response by acting as a chemoattractant. It recruits neutrophils, a type of white blood cell, to sites of inflammation, infection, or tissue damage. Neutrophils are among the first immune cells to arrive at an affected area within minutes of trauma.
IL-8 guides these neutrophils from the bloodstream, across blood vessel walls, and into the surrounding tissue. Once at the site, neutrophils can engulf and destroy pathogens, a process known as phagocytosis, or clean up cellular debris. This directed movement and activation of neutrophils by IL-8 is a component of acute inflammation, allowing the body to mount a rapid defense.
IL-8’s Connection to Health Conditions
While IL-8 is important for a healthy immune response, its dysregulation can contribute to various health conditions. Elevated levels of IL-8 are observed in numerous chronic inflammatory diseases. For example, conditions like rheumatoid arthritis, inflammatory bowel disease (IBD), and psoriasis show increased IL-8 expression.
Respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD) exhibit elevated IL-8 levels, where it contributes to airway inflammation and neutrophil accumulation in the lungs. In certain cancers, IL-8 can promote tumor growth and metastasis by encouraging the formation of new blood vessels, a process called angiogenesis, and by influencing the tumor’s microenvironment. Researchers are investigating IL-8 as a potential therapeutic target in these diseases, aiming to block its effects to manage inflammation and disease progression.