PROTECTIVE EFFECT OF THE PROBIOTIC Saccharomyces boulardii IN Toxocara canis INFECTION IS NOT DUE TO DIRECT ACTION ON THE LARVAE

Abstract

SUMMARYIn a previous study our group found that the probiotic Saccharomyces boulardii was capable of reducing the intensity of infection in mice with toxocariasis. In order to assess whether the mechanism involved would be a direct action of the probiotic on Toxocara canis larvae, this study was designed. Both probiotics were singly cultivated in plates containing RPMI 1640 medium and T. canis larvae. S. boulardii and B. cereus var. toyoi cultures presented 97.6% and 95.7% of larvae with positive motility, respectively, and absence of color by the dye trypan blue, not representing significant difference to the control group (p > 0.05). We conclude that none of the probiotics showed in vitro effects on T. canis larvae and that the interaction with the intestinal mucosa is necessary for the development of the protective effect of S. boulardii. KEYWORDS:Toxocariasis; Probiotics; Larvicidal action.Visceral toxocariasis is a chronic parasitic disease of worldwide distribution 12 currently regarded as a public health problem 17 . This parasitosis, commonly caused by the nematode Toxocara canis, is characterized by the migration and presence of the parasite larvae in humans. These parasites develop in the intestines of dogs, definitive hosts, that contaminate the soil with the parasite eggs. Humans and other paratenic hosts, such as mice, rats, chickens, lambs, and pigs, among others, acquire toxocariasis by ingesting T. canis eggs containing the infective-stage larvae 9 . The larvae hatch in the small intestine, where they perforate the wall and are disseminated by the systemic circulation 14 .The various clinical forms of human toxocariasis complicate treatment, making necessary the search for new alternatives of control and treatment. Although several studies have shown the benefit of the use of probiotics for the prevention and treatment of diseases, few have been conducted to evaluate the preventive effect on protozoosis 10,13,15 and helminthiasis 1,2,3 . The Saccharomyces boulardii, yeast characterized as anti-inflammatory and immunostimulant in the intestinal mucosa 3 , is also related to the reduction of parasite burden in mice infected with T. canis 1 , although the mechanism of action is unknown. Besides this fungus, the Bacillus cereus var. toyoi is a probiotic related to the stimulation of the immune response and promotes animal weight gain 7,8,11 . There is still a gap in the understanding of the mechanism of action of these and other probiotics. In the present study, we evaluated whether there is any larvicidal effect of the probiotics S. boulardii and B. cereus var. toyoi on T. canis larvae in vitro.T. canis eggs were collected directly from the uterine tubes of adult gravid female parasites obtained after the treatment of puppies with pyrantel pamoate (15 mg/kg). Afterwards, the eggs were incubated in 2% formalin solution at 28 °C, with humidity above 90% and oxygenation for 30 days. Then, the extraction of larvae was performed according to DE SAVIGNY (1975). This study was approved by the Ethics Commit...

Zoonotic helminth exposure and risk of allergic diseases: A study of two generations in Norway

“…Changes in microbial diversity in the environment might potentially be of importance for response to helminths, as it has been demonstrated that gut microbiota can alter the response to Toxocara in mice. 40 The age effect in our study, with Toxocara seroprevalence increasing with age in the offspring generation, might reflect a time trend rather than a biological age patterns, and decreasing seroprevalence of Toxocara in more recent birth cohorts is presented in Figure 1. Similar trends were observed for Ascaris.…”

“…This may imply that early‐life exposure to Toxocara is a risk factor for development of allergic disease and that the risk resulting from this exposure may not be lifelong. Changes in microbial diversity in the environment might potentially be of importance for response to helminths, as it has been demonstrated that gut microbiota can alter the response to Toxocara in mice …”

Probiotics for the Control of Helminth Zoonosis

“…Moreover, E. faecalis CECT71219 at different doses of 7 × 10 4 (CFU/g), 1.46 × 10 4 CFU in culture and 1 × 10 8 CFU fed in mice showed both in vitro and in vivo larvicidal activity [ 44 ]. In contrast, Avila et al [ 45 ] reported that none of the Saccharomyces boulardii and Bacillus cereus var . toyoi showed in vitro effects against T. canis larvae.…”

Modulation of IL‐12 and IFNγ by probiotic supplementation promotes protection against Toxocara canis infection in mice

“…It is important to clarify that the time points of 24 and 48 h were selected based on prior study in which S. boulardii action in just 48 h of infection . In the same study, a group of animals was kept receiving probiotic up to 60 days after infection and was observed that the reduction rate was similar to the observed at 48 h. This result suggests that the probiotic action might occur in the first 48 h. The mechanism of action of this probiotic is unknown, what is known so far is that S. boulardii does not exert a direct effect on the parasite larvae . Considering that S. boulardii modulates the structure and the activity of adhesions of the intestinal mucosa and these effects could contribute to the enhancement of intestinal cell restitution , this study aimed to understand the possible immunomodulatory mechanism of S. boulardii in mice experimentally infected by T. canis .…”