Efeito modulatório da coinfecção pelo Mycobacterium bovis na resposta imunológica de camundongos infectados com Strongyloides venezuelensis

Abstract

The intestinal parasites are a major medical-health problem, in view of the large number of people involved and the numerous organizational changes which may result in the host. Infections caused by Strongyloides venezuelensis have a local immune response in both lungs as in the intestine, predominantly from the Th2 type, characterized by the production of cytokines IL-4, IL-5, IL-13 and IL-10, resulting in eosinophilia, increased production of mucus, mastocytosis and high levels of IgE. In addition, infections caused by mycobacteria stimulate predominantly an Th1-type immune response characterized by the production of IFN-, IL-12, TNF- and nitric oxide. Tuberculosis, caused by intracellular pathogen Mycobacterium tuberculosis, is one of the most important infectious diseases, accounting for approximately 2.9 million deaths and 8 million new cases per year. Are still scarce papers involving co-infections, and because of the complex relationship between parasites and between them and their host, it is necessary criterious evaluations. This study evaluated the modulatory effect that the virulent Mycobacterium bovis has on the immune response of mice co-infected with S. venezuelensis. The results showed that the profile of immune response during infection with S. venezuelensis seems to be directly influenced by the presence of M. bovis, because the profile of Th2 response, specific to the worm, was reduced in co-infected animals. This decline could be observed by increasing the number of eggs and worms in animals co-infected when compared with animals infected only with S. venezuelensis, as well as decreased levels of IgE specific to the L3 larvae of the worm detected at different points of infection, decreased levels of IL-10 produced by spleen cells stimulated in vitro with L3 larvae antigen; decreased levels of IL-4, IL-5 and IL-13 in the intestine, reducing the expression of CD80, CD86 and CD25 cells in the spleen and lymph nodes and increased expression of CD28 cells in mesenteric lymph nodes. Together, these results suggest that infection with M. bovis, and the consequent activation of the profile of Th1-type immune response, was able to modulate the development of the profile of Th2 type of immune response against S. venezuelensis in co-infected animals, leaving them more susceptible to infection with S. venezuelensis. This work is the first to evaluate the mechanisms involved in imunoregulatory mechanisms involved in co-infection S. venezuelensis versus M. bovis.