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Influence of Lactobacillus reuteri on the colonic microbiota in health and DSS-induced colitis
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrativ Fysiologi. (Lena Holm)
Institutionen för Mikrobiologi, Sveriges Lantbruksuniversitet.
Institutionen för Mikrobiologi, Sveriges Lantbruksuniversitet.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrativ Fysiologi. (Lena Holm)
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Aim: To investigate the impact of Lactobacillus reuteri and Dextran Sulphate Sodium (DSS) on the colonic microbiota by investigating bacterial content and composition in the individual colonic mucus layers and mesenteric lymph nodes.

Methods: Rats were divided into 4 groups: control, L. reuteri, DSS and L. reuteri+DSS.     L. reuteri was given as a cocktail containing 109 cfu of four different strains of L. reuteri by gavage daily for 16 days. Colitis was induced by 5% DSS in the drinking water for 9 days. The firmly and loosely mucus layers and mesenteric lymph nodes were collected, homogenized and its bacterial content was monitored using both culturing as well as the molecular method terminal restriction fragment length polymorphism (TRFLP).

Results: In controls, the number of bacteria was significantly lower in the inner firmly adherent mucus layer than the outer loosely adherent layer, indicating a barrier function of the inner mucus layer. The composition of the microbiota was also different between layers. L. reuteri prevented colitis but did not alter the microbiota. DSS obliterated the differences between mucus layers both in terms of number of bacteria, and bacterial composition, indicating that DSS destroys the mucus regardless of the addition of L. reuteri. L. reuteri did however significantly decrease bacterial translocation in the DSS-model.

Conclusion: The firmly adherent mucus layer serves as a barrier towards luminal bacteria. DSS alters the colonic microbiota and destroys the mucus barrier. L. reuteri ameliorates DSS-colitis by decreasing bacterial translocation.

 

Keyword [en]
Experimental colitis, DSS, probiotics, Lactobacillus reueteri, lactobacilli, colonic microbiota, colonic mucus, bacterial translocation, T-RFLP
National Category
Microbiology in the medical area
Research subject
Physiology
Identifiers
URN: urn:nbn:se:uu:diva-112501OAI: oai:DiVA.org:uu-112501DiVA: diva2:287681
Available from: 2010-01-19 Created: 2010-01-14 Last updated: 2010-01-20
In thesis
1. Microcirculation, Mucus and Microbiota in Inflammatory Bowel Disease
Open this publication in new window or tab >>Microcirculation, Mucus and Microbiota in Inflammatory Bowel Disease
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Inflammatory bowel diseases, (IBD), are a group of chronic disorders of the gastro-intestinal tract, and include Crohn’s disease (CD) and Ulcerative Colitis (UC). The pathogenesis is not known, but involves at least in part a loss of tolerance towards the commensal colonic microbiota. In this thesis, we show in animal models of CD and UC that the colonic mucosal blood flow increased compared to healthy animals. This blood flow increase is due to an up regulation of endothelial nitric oxide synthase (NOS). Further, we show in the UC model that the thickness of the firmly adherent colonic mucus layer increased compared to healthy animals. This increase is due to an up regulation of inducible NOS in the epithelium. Both the blood flow and mucus thickness increase appear to be protective mechanisms.  We demonstrate that the firmly adherent colonic mucus layer acts as a partial barrier towards luminal bacteria. In the UC model, this barrier is destroyed, causing increased bacterial translocation. The adhesion molecule P-selectin was up regulated in the UC model, leading to increased interactions between leukocytes and the endothelium, but also increased interactions between platelets and the endothelium. This indicates that not only leukocytes, but also platelets are involved in colonic inflammation. The addition of the probiotic bacterial strain Lactobacillus reuteri prevented disease by normalizing P-selectin levels and endothelial interactions with leukocytes and platelets. Lactobacillus reuteri also decreased bacterial translocation over the epithelium. In summary, this thesis highlights the importance of colonic barrier functions, and investigates the role of the microbiota in experimental IBD.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 59 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 516
Keyword
inflammatory bowel diseases, experimental colitis, DSS, TNBS, colonic mucosal blood flow, laser-doppler flowmetry, colonic mucus thickness, MUC2, colonic mucosal barrier function, iNOS, eNOS, probiotics, Lactobacilli, Lactobacillus reuteri, colonic microbiota, T-RFLP, bacterial translocation, intravital microscopy, P-selectin, leukocyte recruitment, platelet recruitment
National Category
Physiology
Research subject
Physiology
Identifiers
urn:nbn:se:uu:diva-112718 (URN)978-91-554-7710-3 (ISBN)
Public defence
2010-03-06, Auditorium Minus, Museum Gustavianum, Akademigatan 3, Uppsala, 13:15 (Swedish)
Opponent
Supervisors
Available from: 2010-02-12 Created: 2010-01-19 Last updated: 2010-02-12Bibliographically approved

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Schreiber, OlofPetersson, JoelSiemiatkowska, AnnaPhillipson, MiaHolm, Lena

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