Leukotrienes: What are they?
Leukotrienes are substances involved in asthmatic, allergic and inflammatory reactions.
They are secreted by some types of white blood cells, hence the name " leuko " (white blood cells) + " trienes " (three conjugated double bonds between carbon atoms). Their distribution in the body is almost ubiquitous.
Leucotirenes are synthesized starting from arachidonic acid, thanks to the action of the 5-lipoxygenase enzyme.
Role in Asthma
Leukotrienes are released by leukocytes and other cells during allergic and inflammatory reactions.
The most evident and well-known action, typical of a subgroup of leukotrienes called cysteinyl erythotrienes (LTC 4, LTD 4, LTE 4 ), is to determine the constriction of the bronchioles located within the lung tissue, in a 1, 000 times more intense than that caused by histamine.
In addition to this action, cysteinylucotrienes increase mucus production (phlegm), increase vascular permeability (edema) and have an eosinophilotactic action (recall eosinophils).
Allergens, substances capable of triggering an allergic reaction or an asthmatic crisis in predisposed people, act by stimulating, among other things, the release of leukotrienes at the bronchial level. In response to the release of these and other spasmogens, the smooth, and therefore involuntary, airway muscle contracts, making breathing difficult.
leukotriene
Given their importance in the etiopathogenesis of asthma and allergies, pharmaceutical companies have long worked to discover drugs capable of inhibiting leukotriene synthesis. The result of these efforts was the recent entry into therapy of the antileucotrienici (Zafirlukast - Accoleit and Zafiist - Montelukast - Lukasm, Montegen, Singulair -).
These medicines do not prevent the synthesis of leukotrienes but block their interaction with receptors present at the bronchial and pulmonary level.
Antileucotrienes are indicated for the prevention of stress-induced asthma (induced by exercise). They are less effective than inhaled corticosteroids (flunisolide, beclomethasone) and long-acting β2-adrenergic agonists (salmeterol) but, thanks to their reduced side effects, they can be used in association with them as support or second-line drugs.
