Passeando pela interação microrganismo-hospedeiro: responsividade inflamatória e suas implicações frente a relações mutualísticas e parasitárias

Abstract

Microorganisms and their host interact in myriad of states along a continuum, ranging from mutualistic relationships, in one extreme, to conflictuous, frequently pathogenic relationships, in the other edge. The aim of the present work was to evaluate the relevance of indigenous microbiota for host inflammatory responsiveness and the potential outcomes of this inflammatory responsiveness during encounters with pathogenic microorganisms. Specifically, results presented here demonstrate that, after colonization by indigenous microbiota, there is a shift in host responsiveness upon inflammatory stimuli, from innate anti-inflammatory mediator production to rapid release of inflammatory mediators and leukocyte mobilization. This altered pattern of inflammatory mediator production is essential for the host ability to control an infectious insult. In addition, the work presented here shows that production of some inflammatory mediators is indispensable for host resistance to infection by Dengue virus, an important human pathogen. On the other hand, some inflammatory mediators released during host response to Dengue virus infection play a pathogenic role, leading to more severe disease manifestation and to increased host susceptibility to infection. Therefore, host colonization by indigenous microorganisms enables its responsiveness to inflammatory stimuli. This gained ability is essential for the host to deal with parasitic microorganisms. However, the capacity of producing inflammatory mediators and mobilizing leukocytes confers the potential to cause tissue damage upon interaction with infectious agents. Thus, host inflammatory responsiveness is directly associated to the outcome of the several ecological relationships established between a host and any microorganism.