One important risk factor for the development of
asthma is
allergen sensitization. Recent increasing evidence suggests a prominent role of mast cells in
asthma pathophysiology. Since
Palmitoylethanolamide (PEA), an endogenous
lipid mediator chemically related to - and co-released with- the
endocannabinoid anandamide, behaves as a local
autacoid down-regulator of mast cell activation and
inflammation, we explored the possible contribution of PEA in allergic sensitization, by using
ovalbumin (OVA) as sensitizing agent in the mouse. PEA levels were dramatically reduced in the bronchi of OVA-treated animals. This effect was coupled to a significant up-regulation of CB2 and GPR55 receptors, two of the proposed molecular PEA targets, in bronchi harvested from
allergen-sensitized mice. PEA supplementation (10 mg/kg, 15 min before each
allergen exposure) prevented OVA-induced
bronchial hyperreactivity, but it did not affect
IgE plasma increase. On the other hand, PEA abrogated
allergen-induced cell recruitment as well as
pulmonary inflammation. Evaluation of pulmonary sections evidenced a significant inhibitory action of PEA on pulmonary mast cell recruitment and degranulation, an effect coupled to a reduction of
leukotriene C4 production. These findings demonstrate that
allergen sensitization negatively affects PEA bronchial levels and suggest that its supplementation has the potential to prevent the development of
asthma-like features.