Saccharomyces boulardii (S. boulardii) has beneficial effects in the treatment of intestinal inflammation; however, little is known about the mechanisms by which these effects occur. We investigated the effects of S. boulardii on the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and interleukin-8 (IL-8), using human HT-29 colonocytes and a rat model of trinitrobenzene sulfonic acid (TNBS)-induced colitis. The effect of S. boulardii on gene expression was assessed by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), and Northern blot and Western blot assays. Pharmacological inhibitors for various signaling pathways were used to determine the signaling pathways implicated in the S. boulardii regulation of PPAR-γ and IL-8. We found that S. boulardii up-regulated and down-regulated PPAR-γ and IL-8 expression at the transcription level, both in vitro and in vivo (P∈<∈0.05, respectively). Saccharomyces boulardii blocked tumor necrosis factor-alpha (TNF-α) regulation of PPAR-γ and IL-8 through disruption of TNF-α-mediated nuclear factor kappa B (NF-κB) activation. Furthermore, S. boulardii suppressed colitis and expression of pro-inflammatory cytokine genes in vivo (P∈<∈0. 05, respectively). Our study demonstrated that S. boulardii reduces colonic inflammation and regulates inflammatory gene expression.
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