Probiotics and prebiotics are emerging household terms, whose claimed health benefits share commonality. Their attributed health benefits include the production or induction of short chain fatty acids, maintaining bowel function, building colonization resistance (against pathogens) and treating antibiotic-associated diarrhea as well as colitis. Although both probiotic and prebiotic effects on immune system have been studied, the mechanisms of their activity are still not clearly defined and the conclusions drawn are elusive. While probiotics can act to influence the host at the cellular level, prebiotics, by definition, exert their effects indirectly through their impact on gut microbes. One purpose of this study was to investigate effects of Lactobacillus rhamnosus R0011 on innate immune parameters at the intestinal epithelial cell level, examining effects on both human and rat IEC. A second purpose was to define the effects of a range of prebiotic dietary fibres on the immune system at the mucosal and systemic level, using Biobreeding rats.
L. rhamnosus demonstrated the ability to decrease proinflammatory cytokine and Toll-like receptor agonist-induced IL-8 and CINC-1 production from human and rat IEC, respectively. The timing of L. rhamnosus R0011 addition to HT-29 IEC, relative to proinflammatory challenge, influenced its ability to decrease IL-8 production. L. rhamnosus was more effective at decreasing production of IL-8 from human IEC when they were pre-incubated with this bacterium and subsequently challenged with proinflammatory stimuli. Certain effects of L. rhamnosus R011 were also observed in the absence of proinflammatory stimuli. Viable L. rhamnosus induced TNF-α production from rat IEC and heat-killed L. rhamnosus decreased constitutive TGF-β production from rat IEC and induced IL-8 or CINC-1 production from human and rat IEC, respectively. In Biobreeding rats, we demonstrated that oat dietary fibre significantly alters active TGF-β, CINC-1 and IL-6 levels in the colon in comparison to AIN-93G-fed rats. Wheat dietary fibre induced changes in active TGF-β, CINC-1 and IL-4 levels in the ileum in comparison to resistant starch-fed rats. Lastly, resistant starch exerted effects in the mesenteric lymph node, where changes in active TGF-β were observed in rats in comparison to AIN-93G-fed rats. Oat bran, wheat bran and resistant starch had no effects on cytokine levels in the serum or spleen of rats. Fructooligosaccharide-fed rats had a significant increase in active TGF-β levels in the colon and a significant decrease in active TGF-β levels in the spleen. Overall this suggests a FOS supplemented diet has both mucosal and systemic effects in rats, while wheat, oat and resistant starch supplemented diets had effects focused at the different locations at the mucosal level.
These results illustrate differences in the ability of different dietary fibres to target immune parameters in specific mucosal tissues along the gastrointestinal tract and differential ability to exert systemic effects. Understanding the mechanism of action of probiotics provides insight into the downstream effects of prebiotics, while investigating effects of prebiotics on the immune system provides a broader view of the outcome of changes in gut microbiota composition and activity at the host organism level. / UOIT
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OOSHDU.10155/275 |
| Date | 01 August 2012 |
| Creators | McCarville, Justin |
| Contributors | Green-Johnson, Julia |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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