Gut microbial diversity is reduced by the probiotic VSL#3 and correlates with decreased TNBS-induced colitis

Abstract

Background: Compositional changes within the normal intestinal microbiota have been associated with the development of various intestinal inflammatory disorders such as pouchitis and inflammatory bowel diseases (IBD). Therefore, it has been speculated that manipulation of a dysbiotic intestinal microbiota has the potential to restore microbial homeostasis and attenuate inflammation.

Methods: We performed community composition analyses by terminal restriction fragment length polymorphism (T-RFLP) of the bacterial 16S ribosomal RNA gene to investigate the impact of the probiotic VSL#3 on colonic microbial community composition and development of trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats.

Results: TNBS-induced chronic colitis was significantly reduced in VSL#3-fed rats compared to controls (P < 0.05). T-RFLP analysis revealed distinct microbial communities at luminal versus mucosal sites. Within the luminal microbiota, chronic colitis was associated with an overall decrease in bacterial richness and diversity (Margalef's richness, P < 0.01; Shannon diversity, P < 0.01). This decrease in luminal microbial diversity was enhanced in TNBS-treated rats fed VSL#3 (Margalef's richness, P < 0.001; Shannon diversity, P < 0.001) and significantly correlated with reduced clinical colitis scores (Pearson correlation P < 0.05).

Conclusions: Our data demonstrate that the probiotic VSL#3 alters the composition of the intestinal microbiota and these changes correlate with VSL#3-induced disease protection.

Copyright © 2010 Crohn's & Colitis Foundation of America, Inc.

Figures

Figure 1

VSL#3 reduces the severity of chronic colitis in TNBS-treated rats. Proximal colon clinical scores for non-TNBS-treated rats and TNBS-treated rats that received either VSL#3 or water. Non-TNBS, n=3; TNBS +water, n = 17, TNBS +VSL#3, n = 16. *p = 0.05. Non-TNBS vs. TNBS +water, or vs. TNBS +VSL#3, p

Figure 2

VSL#3 administration decreases the biodiversity of the luminal microbiota. A. Measures of microbial biodiversity in the luminal compartment of each treatment group. Red = Non-TNBS (n=7); Blue = TNBS +water (n=6); Green = TNBS +VSL#3 (n=7). *p

Figure 3

VSL#3 does not affect the biodiversity or species distribution of the mucosally-adherent microbiota. A. Measures of microbial biodiversity within the mucosally-adherent compartment of each treatment group (TNBS +water n=17, TNBS +VSL#3 n=16). “ns” denotes no significant difference between groups. B. Percent contribution of T-RFs within the luminal compartment of each group (from top 90%). Each color represents a different sized T-RF indicating a different bacterial group.

Figure 4

Distinct microbial community communities reside in the colonic lumen and mucosal tissue. A. Hierarchical cluster analysis of T-RF data from TNBS-treated rats. Mucosally-adherent populations are represented by blue triangles and luminal populations by green triangles. B. Measures of microbial biodiversity in the colonic lumen and mucosal tissue. Blue = luminal (n=13); Green = mucosal (n=33). “ns” denotes no significant difference between groups. C. Percent contribution of T-RFs from each site (from top 90%). Each color represents a different sized T-RF indicating a different bacterial group. Regions in bold represent the 4 bacterial groups within the top 90% contributors in the microbiota of both the colonic lumen and mucosa.

Figure 5

Clinical score of VSL#3-fed rats correlates with luminal species richness and biodiversity. Luminal microbial Margalef's richness vs. clinical score (top panel); Pearson correlation for TNBS/water group, p=0.348; for TNBS/VSL#3, *p=0.021. Luminal microbial Shannon diversity vs. clinical score (bottom panel); Pearson correlation for TNBS/water group, p=0.183; for TNBS/VSL#3, p=0.021.