Interactions Between the Microbiota and the Immune System

The Howard Hughes Medical Institute and Department of Immunology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.
Science (Impact Factor: 33.61). 06/2012; 336(6086):1268-73. DOI: 10.1126/science.1223490
Source: PubMed


The large numbers of microorganisms that inhabit mammalian body surfaces have a highly coevolved relationship with the immune system. Although many of these microbes carry out functions that are critical for host physiology, they nevertheless pose the threat of breach with ensuing pathologies. The mammalian immune system plays an essential role in maintaining homeostasis with resident microbial communities, thus ensuring that the mutualistic nature of the host-microbial relationship is maintained. At the same time, resident bacteria profoundly shape mammalian immunity. Here, we review advances in our understanding of the interactions between resident microbes and the immune system and the implications of these findings for human health.

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Available from: Andrew J Macpherson, Aug 11, 2015
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    • "Through effects on host nutrition, health and behavior, the mammalian gut microbiota can impact host ecology strongly (Amato 2013; Foster and McVey Neufeld 2013; Kau et al. 2011; Ley et al. 2008). In addition, studies of humans and animal models suggest that changes in host diet can alter the composition of the gut microbial community , which in turn affects factors such as host digestive efficiency, immune response, and stress response (Bailey 2012; Bauer et al. 2006; David et al. 2014; Hooper et al. 2012; Hume and Warner 1980; Turnbaugh et al. 2009). Variation in these processes influences host reproductive potential and fitness (Altmann 1998; Dunbar 1980; Gogarten et al. 2012; Hamilton 1985), making the understanding of host-gut microbe interactions in natural , selective environments critical for studies of mammalian evolution. "
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    ABSTRACT: Recent studies suggest that variation in diet across time and space results in changes in the mammalian gut microbiota. This variation may ultimately impact host ecology by altering nutritional status and health. Wild animal populations provide an excellent opportunity for understanding these interactions. However, compared to clinical studies, microbial research targeting wild animals is currently limited, and many published studies focus only on a single population of a single host species. In this study we utilize fecal samples from two species of howler monkey (Alouatta pigra and A. palliata) collected at four sites to investigate factors influencing the gut microbiota at three scales: taxonomic (host species), ecosystemic (forest type), and local (habitat disturbance/season). The results demonstrate that the effect of host species on the gut microbiota is stronger than the effect of host forest type, which is stronger than the effect of habitat disturbance or seasonality. Nevertheless, within host species, gut microbiota composition differs in response to forest type, habitat disturbance, and season. Variations in the effect size of these factors are associated both with host species and environment. This information may be beneficial for understanding ecological and evolutionary questions associated with Mesoamerican howler monkeys, as well as determining conservation challenges facing each species. These mechanisms may also provide insight into the ecology of other species of howler monkeys, non-human primates, and mammals.
    Oecologia 01/2016; DOI:10.1007/s00442-015-3507-z · 3.09 Impact Factor
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    • "Therefore, the term " mucosal barrier " seems to properly highlight the pivotal role of the gut in the interaction with microbiota [8]: it is not a static shield but an active apparatus with specialized components. As stated by Bischoff et al. [9] " permeability " is defined as a functional feature of this barrier that on one hand allows the coexistence with bacterial symbionts necessary for our organism and on the other hand prevents luminal penetration of macromolecules and pathogens [10] [11]. Altered intestinal permeability has been documented during several conditions, namely, acute pancreatitis [12], multiple organ failure [13], major surgery [14] [15], and severe trauma [16], and could explain the high prevalence of Gramnegative sepsis and related mortality in critically ill patients [8]. "
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    ABSTRACT: The pathogenesis of inflammatory bowel disease (IBD) is multifactorial with data suggesting the role of a disturbed interaction between the gut and the intestinal microbiota. A defective mucosal barrier may result in increased intestinal permeability which promotes the exposition to luminal content and triggers an immunological response that promotes intestinal inflammation. IBD patients display several defects in the many specialized components of mucosal barrier, from the mucus layer composition to the adhesion molecules that regulate paracellular permeability. These alterations may represent a primary dysfunction in Crohn’s disease, but they may also perpetuate chronic mucosal inflammation in ulcerative colitis. In clinical practice, several studies have documented that changes in intestinal permeability can predict IBD course. Functional tests, such as the sugar absorption tests or the novel imaging technique using confocal laser endomicroscopy, allow an in vivo assessment of gut barrier integrity. Antitumor necrosis factor- α (TNF- α ) therapy reduces mucosal inflammation and restores intestinal permeability in IBD patients. Butyrate, zinc, and some probiotics also ameliorate mucosal barrier dysfunction but their use is still limited and further studies are needed before considering permeability manipulation as a therapeutic target in IBD.
    Mediators of Inflammation 11/2015; 2015(5):1-10. DOI:10.1155/2015/628157 · 3.24 Impact Factor
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    • "These microbes derive nutrients from the host environment, and in turn, they influence normal animal development and health. The gastrointestinal microbiota are critical for nutrient acquisition and immune system development (Bä ckhed et al., 2005; Hooper et al., 2012). Metagenomic profiling of gut microbiota has identified deviations from taxonomic compositions associated with health in diseases such as obesity (Turnbaugh et al., 2009), diabetes (Wen et al., 2008), and inflammatory bowel diseases (IBD)(Frank et al., 2007). "
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    ABSTRACT: Predicting host health status based on microbial community structure is a major goal of microbiome research. An implicit assumption of microbiome profiling for diagnostic purposes is that the proportional representation of different taxa determine host phenotypes. To test this assumption, we colonized gnotobiotic zebrafish with zebrafish-derived bacterial isolates and measured bacterial abundance and host neutrophil responses. Surprisingly, combinations of bacteria elicited immune responses that do not reflect the numerically dominant species. These data are consistent with a quantitative model in which the host responses to commensal species are additive but where various species have different per capita immunostimulatory effects. For example, one species has a high per capita immunosuppression that is mediated through a potent secreted factor. We conclude that the proportional representation of bacteria in a community does not necessarily predict its functional capacities; however, characterizing specific properties of individual species offers predictive insights into multi-species community function.
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