miércoles, 16 de marzo de 2016

ISCHOM II: Cocoa, prevention & allergy. CASTELL, M.

2.7. Cocoa in the Prevention of Allergy 

Castell, M. 

Allergy is an adverse response in which the immune system reacts against innocuous agents. This response is produced by the activation of Th2 lymphocytes, which, that by means of cytokines, favor the synthesis of IgE antibodies. IgE is able to bind to a receptor present on the surface of mast cells and cause their degranulation that involves the secretion of mediators, such as histamine and proteases. 

The release of mediators will eventually generate allergic symptoms such as urticaria, rhinitis, asthma, and, in the worst cases, anaphylactic shock. There are studies showing the protective effects of flavonoids on allergy (Castell, M., et al. Curr. Pharm. Des. 2014, 20, 973–987). 

Thus, clinical and preclinical studies on respiratory allergy show that flavonoid intake can decrease some respiratory symptoms and the concentration of IgE and histamine in serum. 

On the other hand, previous studies have shown the influence of cocoa diet on immune response in immunized rats, attenuating cytokines and antibodies related to Th2 immune response (Pérez-Berezo, T., et al. Mol. Nutr. Food Res. 2009, 53, 389–397). 

Taking these results into account, we aimed to establish the immunomodulator effect of cocoa on an allergic reaction induced in rats. 

From our results, we saw that allergic rats fed with 10% cocoa diet produced lower amounts of specific IgE and other Th2 antibodies (Abril-Gil, M., et al. Pharmacol. Res. 2012, 65, 603–608), and also Th2 cytokines (Abril-Gil, M., et al. J. Nutr. Biochem. 2015, in press). 

However, after the induction of an anaphylactic response, the alterations induced in motor activity, body temperature, intestinal permeability and hematocrit were not affected by the diet. 

Nevertheless, when we determined the protease released from mast cells, which was much higher in allergic animals, the cocoa diet greatly prevented this increase. Moreover, the cocoa intake produced the downregulation of the gene expression of mast cell IgE receptor and protease in the intestine. 

In order to understand the role of cocoa flavonoids in its anti-allergic ability, we compared the effect of a conventional cocoa diet with a diet containing purer cocoa flavonoids. Results showed that there may be cocoa compounds other than flavonoids that enhance cocoa’s anti-allergic effect (Abril-Gil, M., et al. J. Nutr. Biochem. 2015, in press). 

In conclusion, cocoa, by means of its flavonoids and mainly by other compounds, has the potential to suppress the Th2 immune response and also to attenuate the release of mast cell mediators, but these effects are not enough to completely protect against an anaphylactic response. 

Acknowledgments: Grants AGL2008-02790 and AGL2011-24279 from the Spanish Ministry of Science and Innovation and the Ministry of Economy and Competitiveness, respectively.

ISCHOM II: Barcelona 2016Nutrients.

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