tsütokiine

Tsütokiine (cytokines) are a broad group of small signaling proteins secreted by immune and other cells to mediate and regulate immunity and inflammation. They coordinate a wide range of physiological responses by communicating between cells during infection, injury, and homeostasis.

The cytokine family includes interleukins, interferons, chemokines, tumor necrosis factors, and growth factors. They bind to specific receptors on target cells, often triggering signaling cascades such as JAK-STAT, MAPK, and PI3K-AKT pathways. This signaling can influence gene expression, cell survival, proliferation, and functional activation.

Cytokines can act in autocrine, paracrine, or endocrine manners. Their effects are pleiotropic and highly context-dependent, with redundancy across different cytokines—multiple mediators can produce similar outcomes. They regulate leukocyte development, recruitment, differentiation, and effector functions, and shape both innate and adaptive immunity.

Dysregulation of cytokine production or signaling is linked to a range of conditions. Excessive or chronic cytokine activity can drive inflammatory and autoimmune diseases, while insufficient signaling may impair host defense. Severe infections or therapies can trigger cytokine storms, a potentially life-threatening hyperinflammatory state.

Therapeutically, cytokines and their signaling pathways are common targets. Examples include TNF inhibitors for autoimmune diseases, IL-1 blockers, and IL-6 receptor blockers. JAK inhibitors interrupt downstream signaling of multiple cytokines. Cytokines themselves have been used as therapies (e.g., interferons) in certain diseases, and cytokine profiles serve as biomarkers to aid diagnosis and prognosis.