Anti-eosinophilic effect of Lafoensia pacari in toxocariasis

We previously reported the anti-inflammatory activity of Lafoensia pacari extract in Toxocara canis infection, a model of systemic IL-5-dependent eosinophil migration. In the present study, we describe the kinetics of the anti-inflammatory activity of L. pacari extract and compare it with dexamethasone. T. canis-infected mice were submitted to different treatment protocols and the cells present in bronchoalveolar space and peritoneal cavity were collected at the end of each treatment period. The results showed that L. pacari extract effectively inhibited eosinophil migration only when the treatment was initiated before the peak of eosinophil migration (1st to 18th; 12th to 18th and 12th to 24th day post-infection). When eosinophil migration was established, administration of L. pacari extract had no effect on it (treatment 18th to 24th day post-infection). Dexamethasone was effective in inhibiting eosinophil migration in all periods studied. We suggest that L. pacari extract can potentially be a natural alternative treatment of eosinophilic diseases.

Impact of MK886 on Eosinophil Counts and Phenotypic Features in Toxocariasis

Experimental toxocariasis was used as a model of eosinophil migration. Mice inoculated with 200 Toxocara canis eggs were treated with the leukotriene inhibitor MK886 (1 mg/kg/day). Eosinophils were counted in peripheral blood (PB), peritoneal cavity (PC) and bronchoalveolar lavage fluid (BALF) samples on post-infection days 3, 6, 12, 18, 24 and 36. Eosinophil expression of Mac-1 and VLA-4 was analysed in PB and PC samples. We found that T. canis infection induced systemic eosinophilia from post-infection day 3, peaking on days 6, 12 and 24 in PB, PC and BALF samples respectively. Eosinophilia was more pronounced in PB and PC samples than in BALF samples, and MK886 downregulated eosinophilia to varying degrees in the different sample types. In PB and PC samples, T. canis infection caused early upregulation of Mac-1 with late changes in the VLA-4 profile, whereas MK886 had opposite effects. The distinct time-dependent eosinophilia peaks and differential involvement of leukotrienes in integrin expression demonstrate that, despite the systemic eosinophilia triggered by T. canis infection, inflammatory responses vary by compartment.

Lafoensia pacari extract inhibits IL-5 production in toxocariasis

Toxocariasis is an infection induced by Toxocara canis, an intestinal parasite of dogs. In this study, an experimental murine model of toxocariasis was used to evaluate the anti-inflammatory activity of an ethanolic extract of Lafoensia pacari stem bark. Mice infected with T. canis were treated with L. pacari extract (200 mg/kg, p.o.). Subsequently, we observed a reduction in the number of eosinophils in the peritoneal cavity, bronchoalveolar fluid, blood and bone marrow. Production of interleukin (IL)-5, a major cytokine involved in eosinophilic differentiation, proliferation and activation, is also an important marker for infection. The reduced levels of IL-5 observed in serum, lung homogenates and bronchoalveolar fluid demonstrated the anti-inflammatory mechanisms of L. pacari. Larvae recovery from infected mice treated with L. pacari was comparable with that from untreated mice, suggesting that L. pacari is not toxic to the parasite. Nonetheless, our results demonstrate a potential therapeutic effect of L. pacari extract in IL-5-mediated inflammatory diseases and provide new prospects for the development of drugs to treat IL-5-dependent allergic diseases such as parasite infection and asthma.