Leukotrienes, leukotriene receptor antagonists and leukotriene synthesis inhibitors in asthma: An update. Part I: Synthesis, receptors and role of leukotrienes in asthma

Asthma is a chronic inflammatory disease associated with airflow obstructio n. Airflow obstruction results from contraction of airway smooth muscle, mu cosal oedema, increased secretion of mucus and infiltration of the airway w all by inflammatory cells, particularly eosinophils. Leukotrienes are thoug ht to contribute to the pathophysiology of asthma. Leukotrienes are synthes ised from arachidonic acid by a specific synthesis pathway whose key enzyme is 5-lipoxygenase. Cysteinyl leukotrienes (leukotrienes C-4, D-4 and E-4) have been shown to mimic all the pathologic changes that are characteristic of asthma, whereas leukotriene B-4 does not appear to exert biological pro perties relevant to asthma. Cysteinyl leukotrienes bind to two receptor sub types: CpsLT(1) and CysLT(2). Most of the biological properties of cysteiny l leukotrienes relevant to asthma are mediated through CysLT(1) receptor st imulation. (C) 1999 Academic Press.