The Key Role of Segmented Filamentous Bacteria in the Coordinated Maturation of Gut Helper T Cell Responses

INRA, U910, Unité Ecologie et Physiologie du Système Digestif, Domaine de Vilvert, 78350 Jouy-en-Josas, France.
Immunity (Impact Factor: 19.75). 10/2009; 31(4):677-89. DOI: 10.1016/j.immuni.2009.08.020
Source: PubMed

ABSTRACT Microbiota-induced cytokine responses participate in gut homeostasis, but the cytokine balance at steady-state and the role of individual bacterial species in setting the balance remain elusive. Herein, systematic analysis of gnotobiotic mice indicated that colonization by a whole mouse microbiota orchestrated a broad spectrum of proinflammatory T helper 1 (Th1), Th17, and regulatory T cell responses whereas most tested complex microbiota and individual bacteria failed to efficiently stimulate intestinal T cell responses. This function appeared the prerogative of a restricted number of bacteria, the prototype of which is the segmented filamentous bacterium, a nonculturable Clostridia-related species, which could largely recapitulate the coordinated maturation of T cell responses induced by the whole mouse microbiota. This bacterium, already known as a potent inducer of mucosal IgA, likely plays a unique role in the postnatal maturation of gut immune functions. Changes in the infant flora may thus influence the development of host immune responses.

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Available from: Giovanni Brandi, Jul 28, 2015
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    • "The secreted protein, p40, from Lactobacilli LGG ameliorates cytokine-mediated apoptosis and disruption of the gut epithelial barrier [1], and flagellin from Escherichia coli Nissle is associated with induction of b-defensin 2 in epithelial cells [2]. Gut microbiota has been shown to direct maturation of the host immune system [3], to play a key role in the induction of immunoglobulin (Ig) A [4] [5] and germinal centers [6], and to drive Th1, Th17, and regulatory T cell (Treg) development in the gut [7] [8] [9]. In most individuals, the commensal-mediated induction of these different components of the immune response is beneficial for host health. "
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    FEBS letters 03/2014; 588(22). DOI:10.1016/j.febslet.2014.03.019 · 3.34 Impact Factor
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    • "B€ ackhed et al., 2005, 2007). Still others play a key role in development of adaptive immunity against respiratory infections (Ichinohe et al., 2011) or mediate postnatal maturation of immune function (Dobber et al., 1992; McFall-Ngai, 2007; Mazmanian et al., 2005, 2008; Gaboriau-Routhiau et al., 2009). In contrast, pathogenic microbes (e.g., Wolbachia and Spiroplasma) negatively manipulate host physiology (Moran et al., 2008) and have caused selective sweeps of host populations [e.g., plague, smallpox, and cholera (Wolf et al., 2001)]. "
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    • "The loss of SFB may not only facilitate colonization by a Gram-negative pathogen such as S. Typhimurium as shown by Croswell et al. [65], but may also predispose the host to the outgrowth of opportunistic Gram-positive bacteria. This possibility is suggested by the strong induction by SFB of the microbicide peptide Reg3␥ [30] [45] [54], the downregulation of which after antibiotic therapy was shown to promote colonization by Vancomycin-resistant enterococcus [66]. The mechanism(s) of the barrier effect of SFB is (are), however, not delineated and more studies are necessary to define whether SFB interferes directly with pathogens by blocking their attachment or competing for nutrients or indirectly by stimulating host defense. "
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