Complement System

The complement system is a complex network of more than 30 plasma proteins that play a crucial role in innate immunity. It acts as one of the body's first lines of defense against infection. These proteins are primarily produced by the liver and circulate in the blood and tissues in an inactive form until activated by specific triggers such as pathogens or tissue injury. The main functions include opsonization, cell lysis, chemotaxis, and clearance. There are three primary activation pathways: classical, lectin, and alternative. All three pathways converge on the activation of component C3, leading to a cascade that results in opsonization, inflammation, cell lysis via MAC formation, and further recruitment/activation of immune cells. Complement activity is tightly regulated by various control proteins to prevent damage to host tissues. Dysregulation can lead to increased susceptibility to infections or contribute to autoimmune diseases/chronic inflammation. Deficiencies or dysfunctions in complement components can result in immunodeficiency syndromes with increased risk for severe infections. Overactivation is implicated in autoimmune diseases, chronic inflammation, and other conditions.

Targeted inhibition of complement components (e.g., C3, C5) or receptors (e.g., C5aR) to reduce inflammation and immune-mediated damage.