leukotrienek

Leukotrienes are a group of lipid mediators derived from arachidonic acid, a polyunsaturated fatty acid found in cell membranes. They play a crucial role in inflammatory and allergic responses, particularly in conditions such as asthma, allergic rhinitis, and other allergic diseases. Leukotrienes are synthesized through the 5-lipoxygenase (5-LO) pathway, which converts arachidonic acid into leukotriene A4 (LTA4), a reactive intermediate that further metabolizes into biologically active leukotrienes, including leukotriene B4 (LTB4), leukotriene C4 (LTC4), leukotriene D4 (LTD4), and leukotriene E4 (LTE4).

Leukotriene B4 is a potent chemotactic agent that attracts neutrophils to sites of inflammation, promoting the recruitment of immune cells to combat pathogens or resolve tissue damage. In contrast, cysteinyl leukotrienes (LTC4, LTD4, and LTE4) are known for their role in promoting bronchoconstriction, mucus secretion, and vascular permeability, contributing to airway inflammation and hyperresponsiveness in asthma. These mediators bind to specific G-protein-coupled receptors, such as BLT1 for LTB4 and cysteinyl leukotriene receptors (CysLT1 and CysLT2) for cysteinyl leukotrienes, triggering downstream signaling pathways that amplify inflammatory responses.

Leukotrienes are synthesized and released by various immune cells, including eosinophils, mast cells, basophils, and macrophages, as well as structural cells like epithelial cells and smooth muscle cells in the airways. Their production is regulated by pro-inflammatory cytokines, such as interleukin-4 (IL-4) and interleukin-13 (IL-13), which enhance the expression of 5-LO and its associated proteins. Due to their involvement in allergic and inflammatory diseases, leukotrienes have become important therapeutic targets. Leukotriene modifiers, such as leukotriene receptor antagonists (e.g., montelukast and zafirlukast) and 5-LO inhibitors (e.g., zileuton), are used to reduce symptoms in conditions like asthma and chronic obstructive pulmonary disease (COPD). Research continues to explore their broader physiological roles and potential as biomarkers for disease activity.