Nadia Vasquez

Bio: Nadia Vasquez is an academic researcher from Conservatoire national des arts et métiers. The author has contributed to research in topics: Dysbiosis & Medicine. The author has an hindex of 6, co-authored 7 publications receiving 3407 citations.

Faecalibacterium prausnitzii is an anti-inflammatory commensal bacterium identified by gut microbiota analysis of Crohn disease patients

Abstract: A decrease in the abundance and biodiversity of intestinal bacteria within the dominant phylum Firmicutes has been observed repeatedly in Crohn disease (CD) patients. In this study, we determined the composition of the mucosa-associated microbiota of CD patients at the time of surgical resection and 6 months later using FISH analysis. We found that a reduction of a major member of Firmicutes, Faecalibacterium prausnitzii, is associated with a higher risk of postoperative recurrence of ileal CD. A lower proportion of F. prausnitzii on resected ileal Crohn mucosa also was associated with endoscopic recurrence at 6 months. To evaluate the immunomodulatory properties of F. prausnitzii we analyzed the anti-inflammatory effects of F. prausnitzii in both in vitro (cellular models) and in vivo [2,4,6-trinitrobenzenesulphonic acid (TNBS)-induced] colitis in mice. In Caco-2 cells transfected with a reporter gene for NF-kappaB activity, F. prausnitzii had no effect on IL-1beta-induced NF-kappaB activity, whereas the supernatant abolished it. In vitro peripheral blood mononuclear cell stimulation by F. prausnitzii led to significantly lower IL-12 and IFN-gamma production levels and higher secretion of IL-10. Oral administration of either live F. prausnitzii or its supernatant markedly reduced the severity of TNBS colitis and tended to correct the dysbiosis associated with TNBS colitis, as demonstrated by real-time quantitative PCR (qPCR) analysis. F. prausnitzii exhibits anti-inflammatory effects on cellular and TNBS colitis models, partly due to secreted metabolites able to block NF-kappaB activation and IL-8 production. These results suggest that counterbalancing dysbiosis using F. prausnitzii as a probiotic is a promising strategy in CD treatment.

Review article: the role of bacteria in onset and perpetuation of inflammatory bowel disease

Abstract: We review the evidence that strongly suggests a role of the intestinal microbiota in the onset and perpetuation of inflammatory bowel disease (IBD). Experimental studies consisted of suppressing micro-organisms from the microbiota (using germ-free or gnotoxenic animals or antibiotics), introducing new micro-organisms or microbial components (e.g. probiotics, CpG-DNA) or selectively increasing some endogenous bacteria (e.g. using prebiotics). Intervention studies were performed in patients or animal models of spontaneous or chemically-induced colitis. Information was also obtained from observational studies that described the composition of the faecal and mucosal microbiota at various stages of the disease process and in controls. Many have used culture-independent techniques that identify bacteria based on the nucleic acid sequence of ribosomal RNA molecules. Microbiota in patients with IBD seem to be characterized by high concentrations of bacteria in contact with the mucosa, instability, the presence of high numbers of unusual bacteria and sometimes a reduction in the biodiversity. Studies searching for a generalized or localized dysbiosis in IBD are discussed, as well as those trying to identify bacterial molecules and receptors, which may be implicated in triggering the inflammatory process.

Patchy distribution of mucosal lesions in ileal Crohn's disease is not linked to differences in the dominant mucosa‐associated bacteria: A study using fluorescence in situ hybridization and temporal temperature gradient gel electrophoresis

Abstract: Background: The mucosa-associated bacteria (MAB) are suspected of being involved in the pathogenesis of Crohn's disease. We analyzed and compared the MAB in noninflamed and inflamed ileal mucosa of Crohn's disease patients (n = 22). Methods: Tissue samples from the inflamed ileal mucosa and from the adjacent noninflamed ileal mucosa were taken from surgical resection specimens. The MAB were investigated using fluorescence in situ hybridization with 7 group-specific probes and temporal temperature gradient gel electrophoresis (TTGE). Results: Samples from both noninflamed and inflamed mucosa were obtained from 15 patients. The distribution of the bacterial populations was not different between noninflamed and inflamed mucosa. The Bacteroidetes phylum was dominant and accounted for 29% of MAB (0%–74%) in noninflamed tissues and 32% (0%–70%) in inflamed areas. The γ Proteobacteria represented 12% (0%–70%) of MAB both in noninflamed and inflamed areas. The Clostridium coccoides group (Firmicutes phylum) represented 15% of MAB in noninflamed tissues versus 7% in inflamed areas. For most of the patients the similarity index between TTGE paired profiles was very high. Conclusion: The dominant MAB do not differ between noninflamed and inflamed ileal mucosa in Crohn's disease. This argues against a localized dysbiosis to explain the patchy distribution of mucosal lesions. (Inflamm Bowel Dis 2007)

Differential Effects of Bifidobacterium pseudolongum Strain Patronus and Metronidazole in the Rat Gut

Abstract: In the luminal contents of metronidazole-treated rats, there was a dominant Bifidobacterium species. A strain has been isolated, its 16S rRNA gene has been sequenced, and the strain has been named Bifidobacterium pseudolongum strain Patronus. In this study, using an experimental model of healthy rats, the effects of metronidazole treatment and B. pseudolongum strain Patronus administration on the luminal and mucosa-associated microbiota and on gut oxidation processes were investigated. Metronidazole treatment and the daily gavage of rats with B. pseudolongum strain Patronus increased the numbers of bifidobacteria in cecal contents and in cecal mucosa-associated microbiota compared with those in control rats. Metronidazole reduced the colonic oxidative damage to proteins. This is the first evidence that B. pseudolongum strain Patronus exerts an effect on a biomarker of oxidative damage by reducing the susceptibility to oxidation of proteins in the colon and the small bowel. Antioxidant effects of metronidazole could be linked to the bifidobacterial increase but also to other bacterial modifications.

Structure, function and diversity of the healthy human microbiome

Abstract: The Human Microbiome Project Consortium reports the first results of their analysis of microbial communities from distinct, clinically relevant body habitats in a human cohort; the insights into the microbial communities of a healthy population lay foundations for future exploration of the epidemiology, ecology and translational applications of the human microbiome.

Structure, function and diversity of the healthy human microbiome

Abstract: Studies of the human microbiome have revealed that even healthy individuals differ remarkably in the microbes that occupy habitats such as the gut, skin and vagina. Much of this diversity remains unexplained, although diet, environment, host genetics and early microbial exposure have all been implicated. Accordingly, to characterize the ecology of human-associated microbial communities, the Human Microbiome Project has analysed the largest cohort and set of distinct, clinically relevant body habitats so far. We found the diversity and abundance of each habitat’s signature microbes to vary widely even among healthy subjects, with strong niche specialization both within and among individuals. The project encountered an estimated 81–99% of the genera, enzyme families and community configurations occupied by the healthy Western microbiome. Metagenomic carriage of metabolic pathways was stable among individuals despite variation in community structure, and ethnic/racial background proved to be one of the strongest associations of both pathways and microbes with clinical metadata. These results thus delineate the range of structural and functional configurations normal in the microbial communities of a healthy population, enabling future characterization of the epidemiology, ecology and translational applications of the human microbiome.

Expert consensus document. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic

Abstract: An expert panel was convened in October 2013 by the International Scientific Association for Probiotics and Prebiotics (ISAPP) to discuss the field of probiotics. It is now 13 years since the definition of probiotics and 12 years after guidelines were published for regulators, scientists and industry by the Food and Agriculture Organization of the United Nations and the WHO (FAO/WHO). The FAO/WHO definition of a probiotic--"live microorganisms which when administered in adequate amounts confer a health benefit on the host"--was reinforced as relevant and sufficiently accommodating for current and anticipated applications. However, inconsistencies between the FAO/WHO Expert Consultation Report and the FAO/WHO Guidelines were clarified to take into account advances in science and applications. A more precise use of the term 'probiotic' will be useful to guide clinicians and consumers in differentiating the diverse products on the market. This document represents the conclusions of the ISAPP consensus meeting on the appropriate use and scope of the term probiotic.

Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa

Abstract: Gut microbial composition depends on different dietary habits just as health depends on microbial metabolism, but the association of microbiota with different diets in human populations has not yet been shown. In this work, we compared the fecal microbiota of European children (EU) and that of children from a rural African village of Burkina Faso (BF), where the diet, high in fiber content, is similar to that of early human settlements at the time of the birth of agriculture. By using high-throughput 16S rDNA sequencing and biochemical analyses, we found significant differences in gut microbiota between the two groups. BF children showed a significant enrichment in Bacteroidetes and depletion in Firmicutes (P < 0.001), with a unique abundance of bacteria from the genus Prevotella and Xylanibacter, known to contain a set of bacterial genes for cellulose and xylan hydrolysis, completely lacking in the EU children. In addition, we found significantly more short-chain fatty acids (P < 0.001) in BF than in EU children. Also, Enterobacteriaceae (Shigella and Escherichia) were significantly underrepresented in BF than in EU children (P < 0.05). We hypothesize that gut microbiota coevolved with the polysaccharide-rich diet of BF individuals, allowing them to maximize energy intake from fibers while also protecting them from inflammations and noninfectious colonic diseases. This study investigates and compares human intestinal microbiota from children characterized by a modern western diet and a rural diet, indicating the importance of preserving this treasure of microbial diversity from ancient rural communities worldwide.