Splenda promoted gut Proteobacteria, dysbiosis, and biochemical MPO reactivity in a spontaneous model of (Bacteroidetes-rich) ileal CD. Our results indicate that although Splenda may promote parallel microbiome alterations in CD-prone and healthy hosts, this did not result in elevated MPO levels in healthy mice, only CD-prone mice. The consumption of sucralose/maltodextrin-containing foods might exacerbate MPO intestinal reactivity only in individuals with a pro-inflammatory predisposition, such as CD.

Background Inflammatory bowel disease (IBD) is a lifelong digestive disease characterized by periods of severe inflammation and remission. To our knowledge, this is the first study showing a variable effect on ileitis severity from human gut microbiota isolated from IBD donors in remission and that of healthy controls in a mouse model of IBD. Methods We conducted a series of single-donor intensive and nonintensive fecal microbiota transplantation (FMT) experiments using feces from IBD patients in remission and healthy non-IBD controls (N = 9 donors) in a mouse model of Crohn’s disease (CD)-like ileitis that develops ileitis in germ-free (GF) conditions (SAMP1/YitFC; N = 96 mice). Results Engraftment studies demonstrated that the microbiome of IBD in remission could have variable effects on the ileum of CD-prone mice (pro-inflammatory, nonmodulatory, or anti-inflammatory), depending on the human donor. Fecal microbiota transplantation achieved a 95% ± 0.03 genus-level engraftment of human gut taxa in mice, as confirmed at the operational taxonomic unit level. In most donors, microbiome colonization abundance patterns remained consistent over 60 days. Microbiome-based metabolic predictions of GF mice with Crohn’s or ileitic-mouse donor microbiota indicate that chronic amino/fatty acid (valine, leucine, isoleucine, histidine; linoleic; P < 1e-15) alterations (and not bacterial virulence markers; P > 0.37) precede severe ileitis in mice, supporting their potential use as predictors/biomarkers in human CD. Conclusion The gut microbiome of IBD remission patients is not necessarily innocuous. Characterizing the inflammatory potential of each microbiota in IBD patients using mice may help identify the patients’ best anti-inflammatory fecal sample for future use as an anti-inflammatory microbial autograft during disease flare-ups.

Crohn’s disease and ulcerative colitis are chronic and progressive inflammatory bowel diseases (IBDs) that are attributed to dysregulated interactions between the gut microbiome and the intestinal mucosa-associated immune system. There are limited studies investigating the role of either IL-1α or IL-1β in mouse models of colitis, and no clinical trials blocking either IL-1 have yet to be performed. In the present study, we show that neutralization of IL-1α by a specific monoclonal antibody against murine IL-1α was highly effective in reducing inflammation and damage in SAMP mice, mice that spontaneously develop a Crohn’s-like ileitis. Anti-mouse IL-1α significantly ameliorated the established, chronic ileitis and also protected mice from developing acute DSS-induced colitis. Both were associated with taxonomic divergence of the fecal gut microbiome, which was treatment-specific and not dependent on inflammation. Anti–IL-1α administration led to a decreased ratio ofProteobacteriatoBacteroidetes, decreased presence ofHelicobacterspecies, and elevated representation ofMucispirillum schaedleriandLactobacillus salivarius. Such modification in flora was functionally linked to the antiinflammatory effects of IL-1α neutralization, as blockade of IL-1α was not effective in germfree SAMP mice. Furthermore, preemptive dexamethasone treatment of DSS-challenged SAMP mice led to changes in flora composition without preventing the development of colitis. Thus, neutralization of IL-1α changes specific bacterial species of the intestinal microbiome, which is linked to its antiinflammatory effects. These functional findings may be of significant value for patients with IBD, who may benefit from targeted IL-1α–based therapies.

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