Immunobiotics and immunity against parasites

5. HUMEN, M. A.; BENYACOUB, J.; MINNAARD, J; BRASSART, D.; DE ANTONI, G. L. SCHIFFRIN, E. J. AND PÉREZ, P. F.

Probiotics: Immunobiotics and Immunogenics.

SCIENCE PUBLISHERS/CRC PRESS, Boca Raton, FL, USA.

Año: 2013; p. 194 - 214

Parasitism represents a ?win-lose? situation in which one organism benefits from the relationship while the other member is harmed by it (Faust and Raes, 2012). Actually, parasites could lead from undetectable or minor effects to debilitating or fatal disease. In addition, it has been demonstrated that interaction with parasites could lead to dramatical modification of the host´s phenotype (Goodman and Johnson, 2011). A broad vision of parasites will include in this group both prokaryote and eukaryote organisms but in this chapter the term ?parasite? refers to protozoan and metazoan organisms able to provoke disease in vertebrates. Parasites have evolved to exploit host´s resources in a way that maximizes the likelihood of their continuity on Earth. Successful parasites preserve their host at least until transmission to another individual is accomplished. Should this step is not complete before host death the parasite will be committed to extinction. In this evolutionary frame, life cycles of several parasites reach high degrees of sophistication in order to guaranty permanence. Life cycle of many parasites includes passage or colonization of the digestive tract and the interaction with the host´s microbiota and factors that lead to the modification of the balance between intestinal inhabitants may affect significantly the infection by parasites. A hallmark in parasite life is the ability to respond to changes in the environment by phenotypic changes that allows the organisms to adapt to very variable conditions. This phenotypic plasticity constitutes a successful strategy for survival (Mideo and Reece, 2012). Several microorganisms have demonstrated to antagonize the effect of intestinal pathogens. Mechanisms involved in these protective ability include barrier effect (i.e. exclusion and growth inhibition) and immunomodulation. Even though the gastrointestinal tract is a natural target for nutritional interventions with microorganisms-containing preparations, effects of these products can go beyond the limits of the gastrointestinal tract (Salva et al., 2010). Whereas there is substantial scientific evidence on the effect of probiotics on the course of bacterial infections, the field of protozoan and metazoan pathogens remains almost unexplored. In this chapter we will describe the biology and cell cycle of parasites for which the effect of probiotic has been studied as well as evidence of the effect of different probiotics on protozoan and metazoan parasites.