Factors associated with the diversification of the gut microbial communities within chimpanzees from Gombe National Park

The gastrointestinal tract harbors large and diverse populations of bacteria that vary among individuals and within individuals over time. Numerous internal and external factors can influence the contents of these microbial communities, including diet, geography, physiology, and the extent of contact among hosts. To investigate the contributions of such factors to the variation and changes in gut microbial communities, authors analyzed the distal gut microbiota of individual chimpanzees from two communities in Gombe National Park, Tanzania.

The role of Helicobacter pylori infection in the development of allergic asthma.

Asthma is one of the most prevalent chronic diseases in developed countries, with steady increases in asthma prevalence evident, particularly in the last few decades. As genetic factors are unlikely to contribute to the rise in asthma prevalence, changes in lifestyle and exposure to environmental stimuli have been proposed to account for this trend.

Insight into the bacterial gut microbiome of the North American moose (Alces alces)

The work presented here provides the first intensive insight into the bacterial populations in the digestive tract of the North American moose (Alces alces). Eight free-range moose on natural pasture were sampled, producing eight rumen samples and six colon samples. Second generation (G2) PhyloChips were used to determine the presence of hundreds of operational taxonomic units (OTUs), representing multiple closely related species/strains (>97% identity), found in the rumen and colon of the moose.

Toll-Like Receptors Promote Mutually Beneficial Commensal-Host Interactions

Toll-like receptors (TLRs) are evolutionarily conserved trans-membrane receptors that detect microorganisms through the recognition of conserved molecular motifs. With each TLR able to recognize a discrete set of microbial ligands, TLRs represent an important mechanism by which the host detects a variety of microorganisms. Triggering of TLRs by pathogens is classically understood to result in an inflammatory immune response that supports the subsequent clearance of the offending microbe. However, animals are stably colonized by a consortium of symbiotic microbes (the microbiota) that possess many of the same structural motifs as pathogens, which raises the question of how the host is able to peacefully coexist with this community of organisms without suffering from chronic inflammatory disease. Paradoxical to its proinflammatory role during infection, recent studies have suggested that commensal bacterial recognition by TLRs is important for limiting inflammation within the intestine. While TLR expression on cells of the innate immune system (macrophages and dendritic cells) is largely thought to account for TLR function, cells of the adaptive immune system (T and B cells) and nonhematopoietic (epithelial) cells also express TLRs. Recent evidence has uncovered that the functional consequence of TLR engagement depends largely on the responding cell type and does not always result in inflammation. In this article authors will highlight how TLR engagement on epithelia, B and T cells promotes mutually beneficial interactions between hosts and their resident microbes.

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The intestinal environment in health and disease - recent insights onthe potential of intestinal bacteria to influence human health

The human intestine is colonized by a complex microbial ecosystem, which could be considered as a separate organ within the human host, having a coding capacity which exceeds the liver by a factor 100. On the one hand, this extensive microbiome is closely involved in the first-pass metabolism and bioavailability of food and drug compounds. Understanding to which extent each individual's gut microbiota affects the bioavailability and response to orally administered drugs is therefore a first important challenge towards novel drug development strategies. On the other hand, as our microbiota is directly or indirectly involved in the onset of a number of disease states, a new generation of therapeutics may be developed that affect the structure and functioning of the intestinal microbiota and interfere with their specific cross-talk with the human host. Ultimately, the intestinal microbiota may even be used as a biomarker for impending diseases inside or outside the gastrointestinal tract and for the evaluation of responses to specific therapeutic interventions. This review will therefore highlight the importance of the indigenous microbial community and its enormous metabolic potential, microbe-microbe interactions, mechanisms of host-bacterium cross-talk and will discuss the onset of obesity, a specific disease state in which the role of intestinal bacteria becomes more and more apparent. Understanding the importance of the intestinal ecosystem in these phenomena may open the door for new strategies which target the management of the intestinal microbiome into the desired direction and therefore to a completely new type of nutrition research and pharmaceutical design.

Microbial Exposure During Early Life Has Persistent Effects on Natural Killer T Cell Function

Researchers from Brigham and Women’s Hospital, (Harvard Medical School) have demonstrated that exposure to microbes during early childhood is associated with protection from immune-mediated diseases such as inflammatory bowel disease (IBD) and asthma. In their article researchers show that, in germ-free mice (GF), invariant natural killer T cells (iNKT) accumulate in the colonic lamina propria and lung, resulting in increased morbidity in models of IBD and allergic asthma compared to specific pathogen-free (SPF) mice. This was associated with increased intestinal and pulmonary expression of the chemokine ligand CXCL16, which was associated with increased mucosal iNKT cells. Colonization of neonatal—but not adult—GF mice with a conventional microbiota protected the animals from mucosal iNKT accumulation and related pathology. These results indicate that age-sensitive contact with commensal microbes is critical for establishing mucosal iNKT cell tolerance to later environmental exposures.

Adapted from: Original source

The normal intestinal microbiota

PURPOSE OF REVIEW: Long neglected and considered a difficult ecosystem to study, several developments have recently converged to renew interest in studying the normal gut microbiota. These include molecular methods of studying the microbiota, improved understanding of host-microbe interactions in health and disease, and the potential for therapeutic manipulation of the microbiota. This review focuses on the most recent work in these areas.

RECENT FINDINGS: Host-microbe signaling in the gut is critical for normal development and homeostasis of the gastrointestinal mucosa. The molecular basis of these interactions promises new therapeutic strategies for various disorders. Particularly noteworthy has been the emergence of evidence for the role of enteric bacterial metabolism in the pathogenesis of disorders ranging from functional and inflammatory bowel diseases to human obesity. Metagenomic and metabolomic profiling of the microbiota, although at an early stage, has demonstrated the range and complexity of the gut ecosystem and cast insights into several diseases. The molecular basis of host-microbe dialogue and the mechanisms by which the host contains enteric bacteria within the lumen has immediate relevance to infectious and chronic inflammatory bowel disease.

SUMMARY: Improved understanding of the normal gut microbiota has made the therapeutic manipulation of the gut ecosystem a valid and realistic future prospect.

Original Source:
http://www.ncbi.nlm.nih.gov/pubmed/17762785

The intestinal microbiome: a separate organ inside the body with themetabolic potential to influence the bioactivity of botanicals

For many years, it was believed that the main function of the large intestine was the resorption of water and salt and the facilitated disposal of waste materials. However, this task definition was far from complete, as it did not consider the activity of the microbial content of the large intestine. Nowadays it is clear that the complex microbial ecosystem in our intestines should be considered as a separate organ within the body, with a metabolic capacity which exceeds the liver with a factor 100. The intestinal microbiome is therefore closely involved in the first-pass metabolism of dietary compounds. This is especially true for botanical supplements, which are now marketed for various health applications. Being of natural origin, their structural building blocks, such as polyphenols, are often highly recognized by the human and especially the intestinal microbial metabolism machinery. Intensive metabolism results in often low circulating levels of the original products, with the consequence that final health effects of botanicals are often related to specific active metabolites which are produced in the body rather than being related to the product's original composition. Understanding how such metabolic processes contribute to the in situ exposure is therefore crucial for the proper interpretation of biological responses. A multidisciplinary approach, characterizing the food and phytochemical intake as well as the metabolic potency of the gut microbiota, while measuring biomarkers of both exposure and response in target tissues, is therefore of critical importance. With polyphenol metabolism as example, this review describes how the incorporation of microbial metabolism as an important variable in the evaluation of the final bioactivity of botanicals strongly increases the relevance and predictive value of the outcome. Moreover, knowledge about intestinal processes may offer innovative strategies for targeted product development.

Original Source:
http://www.ncbi.nlm.nih.gov/pubmed/20655994

Trypanosoma cruzi Immune Response Modulation Decreases Microbiota in Rhodnius prolixus Gut and Is Crucial for Parasite Survival and Development

Trypanosoma cruzi in order to complete its development in the digestive tract of Rhodnius prolixus needs to overcome the immune reactions and microbiota trypanolytic activity of the gut. Authors demonstrate that in R. prolixus following infection with epimastigotes of Trypanosoma cruzi clone Dm28c and, in comparison with uninfected control insects, the midgut contained (i) fewer bacteria, (ii) higher parasite numbers, and (iii) reduced nitrite and nitrate production and increased phenoloxidase and antibacterial activities.

Characterization of Malassezia microbiota in the human external auditory canal and on the sole of the foot

Of the fungal skin microbiota, the lipophilic yeast genus Malassezia predominates at all body sites. Of the members of this genus, M. globosa, M. restricta, and M. sympodialis are the most common on the face, limbs, and trunk. In the present study, the Malassezia microbiotas in the external auditory canal and on the sole of the foot were characterized.

Targeting the human microbiome with antibiotics, probiotics, and prebiotics: gastroenterology enters the metagenomics era

Studies of metagenomics and the human microbiome will tremendously expand our knowledge of the composition of microbial communities in the human body. As our understanding of microbial variation and corresponding genetic parameters is refined, this information can be applied to rational remodeling or "tailoring" of human-associated microbial communities and their associated functions.

Gut microbiota: a potential new territory for drug targeting

The significant involvement of the gut microbiota in human health and disease suggests that manipulation of commensal microbial composition through combinations of antibiotics, probiotics and prebiotics could be a novel therapeutic approach.

Data mining the human gut microbiota for therapeutic targets

It is well known that microbes have an intricate role in human health and disease. However, targeted strategies for modulating human health through the modification of either human-associated microbial communities or associated human-host targets have yet to be realized. New knowledge about the role of microbial communities in the microbiota of the gastrointestinal tract (GIT) and their collective genomes, the GIT microbiome, in chronic diseases opens new opportunities for therapeutic interventions.

Daily follow-up of bacterial communities in the human gut reveals stable composition and host-specific patterns of interaction

In the last decade, an extensive effort has been made to characterize the human intestinal microbiota by means of SSU rRNA gene sequence and metagenomic analysis. Relatively few studies have followed intestinal bacterial communities over time to assess their stability in the absence of perturbation. In this study authors have monitored the faecal bacteria of three healthy subjects during fifteen consecutive days.

Increased honey bee diversity means fewer pathogens, more helpful bacteria, IU biologist finds

Another first, research also finds probiotic species used by humans flourishing in colonies.

A novel study of honey bee genetic diversity co-authored by an Indiana University biologist has for the first time found that greater diversity in worker bees leads to colonies with fewer pathogens and more abundant helpful bacteria like probiotic species.