Specificity of the Adaptive Immune Response to the Gut Microbiota

Peterson, Daniel A.; Cardona, Roberto A. Jimenez

doi:10.1016/b978-0-12-381300-8.00003-4

Cited by 23 publications

(14 citation statements)

References 105 publications

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“…It is known that IgA can control bacterial infection by coating pathogenic bacteria and preventing their physical contact to the epithelium, a process called immune exclusion 76 . However, other mechanisms might be involved, such as changes in the bacterial gene expression by binding of IgA 80 , 81 . The mechanisms by which specific binding of IgA control gut bacterial expansion and diversification—not only of pathogens, but of commensals as well—remain to be solved.…”

Section: Role Of Iga In Gutmentioning

confidence: 99%

Gut T_FH and IgA: key players for regulation of bacterial communities and immune homeostasis

et al. 2013

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The main function of the immune system is to protect the host against pathogens. However, unlike the systemic immune system, the gut immune system does not eliminate, but instead nourishes complex bacterial communities and establishes advanced symbiotic relationships. Immunoglobulin A (IgA) is the most abundant antibody isotype in mammals, produced mainly in the gut. The primary function of IgA is to maintain homeostasis at mucosal surfaces, and studies in mice have demonstrated that IgA diversification has an essential role in the regulation of gut microbiota. Dynamic diversification and constant adaptation of IgA responses to local microbiota require expression of activation-induced cytidine deaminase by B cells and control from T follicular helper and Foxp3 þ T cells in germinal centers (GCs). We discuss the finely tuned regulatory mechanisms for IgA synthesis in GCs of Peyer's patches and emphasize the roles of CD4 þ T cells for IgA selection and the maintenance of appropriate gut microbial communities required for immune homeostasis. The intestine is colonized by a large number of microorganisms that are establishing mutualistic relationships with the host. These microorganisms-mainly composed of bacteria and commonly referred as the gut microbiota-not only serve as a natural competitor for pathogens, but also are essential for nutrient processing, development and regulation of the host immune system. 1 Gut microbiota, which are separated from the host by a single layer of epithelial cells, appear to stimulate constitutively the host mucosal immune system. To control the threshold of such stimulation, mammals evolved very sophisticated regulatory immune mechanism in the gut. [2][3][4][5] The gut immune system has some peculiarities when compared with the systemic immune system. These become obvious when considering that it is important not to eliminate but to peacefully coexist with gut microbiota to prevent the expansion of harmful bacteria yet to retain helpful and diversified bacteria. Gut immune system uniquely and constitutively produces large amounts of immunoglobulin A (IgA) in response to the interaction with gut microbiota. Most of these immune responses are generated in gutassociated lymphoid tissues. In this review, we dissect the uniqueness of gut immune responses, focusing on the characteristics of T follicular helper (T FH ) cells in gut and their association with IgA selection and control of gut microbiota. GUT-ASSOCIATED LYMPHOID TISSUESGut-associated lymphoid tissues are usually divided into two functional compartments: inductive and effector sites. 6,7 The primary inductive sites include organized follicular structures that are present along the wall of intestine, such as Peyer's patches (PPs) and isolated lymphoid follicles. These follicular structures are enriched in B cells interacting with T cells. The lamina propria (LP), particularly of the small intestine (SI), is the main mucosal effector site where many of IgA-producing cells generated in the PPs relocate and reside. The IgAs are ...

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Section: Role Of Iga In Gutmentioning

confidence: 99%

Gut T_FH and IgA: key players for regulation of bacterial communities and immune homeostasis

et al. 2013

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“…The gut microbiota plays a key role in shaping various aspects of postnatal life; it contributes to the development of the immune system [1] , [2] and controls energy balance by influencing energy expenditure and storage [3] . Higher ratio of Firmicutes to Bacteroidetes in the gut has been associated with obesity in mice [4] .…”

Section: Introductionmentioning

confidence: 99%

Isolation and Characterization of Faecalibacterium prausnitzii from Calves and Piglets

et al. 2014

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The goal of our study was to isolate and characterize Faecalibacterium prausnitzii from fecal samples of healthy calves and piglets, in order to develop a novel probiotic for livestock animals. We identified 203 isolates of Faecalibacterium sp., which were clustered in 40 genetically distinct groups. One representative isolate from each cluster was selected for further characterization. The concentrations of the short chain fatty acids (SCFA) acetate, butyrate, propionate and isobutyrate in the culture media were measured by gas chromatography. We observed reduction in the concentration of acetate followed by concomitant increase in the concentration of butyrate, suggesting that the isolates were consuming acetate present in the media and producing butyrate. Butyrate production correlated positively with bacterial growth. Since butyrate has many benefits to the colonic epithelial cells, the selection of strains that produce higher amounts of butyrate is extremely important for the development of this potential probiotic. The effect of pH and concentration of bile salts on bacterial growth was also evaluated in order to mimic the conditions encountered by F. prausnitzii in vivo. The optimal pH for growth ranged between 5.5 and 6.7, while most isolates were inhibited by of the lowest concentration of bile salts tested (0.1%). Antimicrobial resistance profile showed that most isolates of Faecalibacterium sp. were resistant against ciprofloxacin and sulfamethoxazole-trimethoprim. More than 50% of the isolates were resistant to tetracycline, amikacin, cefepime and cefoxitin. A total of 19 different combinations of multidrug resistance were observed among the isolates. Our results provide new insights into the cultural and physiological characteristics of Faecalibacterium prausnitzii illustrating large variability in short chain fatty acid production, in vitro growth, sensitivity to bile salts, and antibiotic resistance and suggesting that future probiotic candidates should be carefully studied before elected for in vivo studies.

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“…Symbiotic fungi of the rumen play a crucial role in releasing otherwise unavailable nutrients from plant matter to herbivores (Trinci et al, 1994). Some wood-boring beetles rely on the enzymes of gut fungi to digest their meals (Nguyen et al, role of micro-organisms in human health (Martins dos Santos et al, 2010, Peterson and Cardona, 2010and Walter, 2008. However, prokaryotes are not the only components of the mammalian gut microbiota.…”

Section: Introductionmentioning

confidence: 99%

Fungi inhabiting the healthy human gastrointestinal tract: a diverse and dynamic community

Kachman²,

et al. 2015

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Specificity of the Adaptive Immune Response to the Gut Microbiota

Cited by 23 publications

References 105 publications

Gut T_FH and IgA: key players for regulation of bacterial communities and immune homeostasis

Gut T_FH and IgA: key players for regulation of bacterial communities and immune homeostasis

Isolation and Characterization of Faecalibacterium prausnitzii from Calves and Piglets

Fungi inhabiting the healthy human gastrointestinal tract: a diverse and dynamic community

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Specificity of the Adaptive Immune Response to the Gut Microbiota

Cited by 23 publications

References 105 publications

Gut TFH and IgA: key players for regulation of bacterial communities and immune homeostasis

Gut TFH and IgA: key players for regulation of bacterial communities and immune homeostasis

Isolation and Characterization of Faecalibacterium prausnitzii from Calves and Piglets

Fungi inhabiting the healthy human gastrointestinal tract: a diverse and dynamic community

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Product

Resources

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Gut T_FH and IgA: key players for regulation of bacterial communities and immune homeostasis

Gut T_FH and IgA: key players for regulation of bacterial communities and immune homeostasis