Eosinophils increase macrophage ability to control intracellular Leishmania amazonensis infection via PGD2 paracrine activity in vitro.

Clinical and experimental studies have described eosinophil infiltration in Leishmania amazonensis infection sites, positioning eosinophils strategically adjacent to the protozoan-infected macrophages in cutaneous leishmaniasis. Here, by co-culturing mouse eosinophils with L. amazonensis-infected macrophages, we studied the impact of eosinophils on macrophage ability to regulate intracellular L. amazonensis infection. Eosinophils prevented the increase in amastigote numbers within macrophages by a mechanism dependent on a paracrine activity mediated by eosinophil-derived prostaglandin (PG) D2 acting on DP2 receptors. Exogenous PGD2 mimicked eosinophil-mediated effect on managing L. amazonensis intracellular infection by macrophages and therefore may function as a complementary tool for therapeutic intervention in L. amazonensis-driven cutaneous leishmaniasis.

Uvaol attenuates pleuritis and eosinophilic inflammation in ovalbumin-induced allergy in mice.

Uvaol, a triterpene present in olives and virgin olive oil, has been shown to possess anti-inflammatory properties and antioxidant effects. However, until now, no studies have demonstrated its potential effects on allergic inflammation. The aim of this study was to evaluate the anti-inflammatory effects of uvaol in a mouse model of allergy characterized by eosinophil-dominant inflammation in actively sensitized mice. The anti-inflammatory effect of uvaol was analyzed in two murine models of allergic inflammation (pleurisy and asthma). In these models, Swiss mice were sensitized and challenged with ovalbumin (OVA). In the pleurisy model, the pleural eosinophilic inflammation and IL-5 concentrations were examined 24h after the OVA challenge, while in the asthma model were examined the airway inflammation via bronchoalveolar lavage (BAL) fluid cytology and lung histopathology analyses. Our results showed that uvaol decreased the accumulation of eosinophils and the concentration of IL-5 in pleural effluent. Uvaol also demonstrated important anti-inflammatory activity by inhibiting production of IL-5 and influx of leukocytes, mainly of eosinophils, in BAL fluid, but without interfering with levels of reactive oxygen species in leukocytes. Moreover, the eosinophil infiltration, mucus production, number of alveoli that collapsed, and IL-5 levels in the lung were clearly decreased by uvaol treatment. These findings indicate that uvaol can be a good candidate for the treatment of allergic inflammation by inhibiting eosinophil influx and IL-5 production in ovalbumin-induced allergy.