Disodium cromoglycate inhibits visceral hypersensitivity in stress-prone Wistar Kyoto rats.

<p>Colorectal distension-induced pain behaviors in Wistar Kyoto (WKY) animals were significantly greater than those observed in Sprague Dawley (SD) animals (A, threshold; B, total pain behaviours). Pre-treatment with 50 mg kg^-1 disodium cromoglycate (DSCG) significantly increased the pressure required to induce the first pain behaviour (C, threshold) and decreased the total number of pain behaviours (D) in WKY animals. n= 7-8. * <i>p</i><0.05, ** <i>p</i> <0.01, <i>versus</i> SD. # <i>p</i> <0.05, ## <i>p</i> <0.01, <i>versus</i> vehicle. </p

Wistar Kyoto rat colon displays altered sensitivity to compound 48/80 and disodium cromoglycate <i>in</i><i>vitro</i>.

<p>The change in short-circuit current (Isc) induced by compound 48/80 was significantly decreased in Wistar Kyoto (WKY) colon, and sensitive to inhibition by disodium cromoglycate (DSCG; A). Though WKY and Sprague Dawley tissues responded in a similar manner to forskolin stimulation, only the WKY response was sensitive to inhibition by DSCG. n=7-8, ** <i>p</i> <0.01, *** p<0.001, <i>versus</i> SD. # <i>p</i> <0.05, ## <i>p</i> <0.01, <i>versus</i> vehicle. </p

Changes in submucosal mast cell number and peritoneal mast cell classification in Wistar Kyoto rats.

<p>Colons from Wistar Kyoto (WKY) animals displayed a significantly greater number of Alcian blue (A and B, black arrow head) and RMCPII (C and D, white arrow head) positive submucosal connective tissue mast cells relative to Sprague Dawley (SD; <i>insert</i>) animals (* <i>p</i><0.05, ** <i>p</i><0.01 <i>versus</i> SD, n=10-15). Purified peritoneal mast cells isolated from SD animals were predominantly safranin positive (F, black arrow head), and therefore considered CTMC, while equal proportions of those isolated from WKY animals were either safranin positive or Alcian blue/safranin positive (F; white arrow heads), representing CTMC and intermediate mast cells respectively. n=4. * <i>p</i><0.05, versus s⁺. # <i>p</i><0.05, ## <i>p</i><0.01, <i>versus</i> SD. </p

Stimulated release of colonic mast cell mediators was insensitive to inhibition by disodium cromoglycate.

<p>Compound 48/80 (10 µg ml^-1)-stimulated RMCPII release was significantly greater from Wistar Kyoto (WKY) colons relative to Sprague Dawley (SD; A) tissues and was insensitive to inhibition by DSCG (C). Similarly, histamine release was neither elevated from WKY colon relative to SD tissues (B), nor sensitive to inhibition by DSCG (D). n= 7-8. ** <i>p</i> <0.01, <i>versus</i> SD. </p

Inflammasome Signaling Regulates the Microbial–Neuroimmune Axis and Visceral Pain in Mice

Interactions between the intestinal microbiota, immune system and nervous system are essential for homeostasis in the gut. Inflammasomes contribute to innate immunity and brain–gut interactions, but their role in microbiota–neuro–immune interactions is not clear. Therefore, we investigated the effect of the inflammasome on visceral pain and local and systemic neuroimmune responses after antibiotic-induced changes to the microbiota. Wild-type (WT) and caspase-1/11 deficient (Casp1 KO) mice were orally treated for 2 weeks with an antibiotic cocktail (Abx, Bacitracin A and Neomycin), followed by quantification of representative fecal commensals (by qPCR), cecal short chain fatty acids (by HPLC), pathways implicated in the gut–neuro-immune axis (by RT-qPCR, immunofluorescence staining, and flow cytometry) in addition to capsaicin-induced visceral pain responses. Abx-treatment in WT-mice resulted in an increase in colonic macrophages, central neuro-immune interactions, colonic inflammasome and nociceptive receptor gene expression and a reduction in capsaicin-induced visceral pain. In contrast, these responses were attenuated in Abx-treated Casp1 KO mice. Collectively, the data indicate an important role for the inflammasome pathway in functional and inflammatory gastrointestinal conditions where pain and alterations in microbiota composition are prominent

Dietary-Induced Bacterial Metabolites Reduce Inflammation and Inflammation-Associated Cancer via Vitamin D Pathway

Environmental factors, including westernised diets and alterations to the gut microbiota, are considered risk factors for inflammatory bowel diseases (IBD). The mechanisms underpinning diet-microbiota-host interactions are poorly understood in IBD. We present evidence that feeding a lard-based high-fat (HF) diet can protect mice from developing DSS-induced acute and chronic colitis and colitis-associated cancer (CAC) by significantly reducing tumour burden/incidence, immune cell infiltration, cytokine profile, and cell proliferation. We show that HF protection was associated with increased gut microbial diversity and a significant reduction in Proteobacteria and an increase in Firmicutes and Clostridium cluster XIVa abundance. Microbial functionality was modulated in terms of signalling fatty acids and bile acids (BA). Faecal secondary BAs were significantly induced to include moieties that can activate the vitamin D receptor (VDR), a nuclear receptor richly represented in the intestine and colon. Indeed, colonic VDR downstream target genes were upregulated in HF-fed mice and in combinatorial lipid-BAs-treated intestinal HT29 epithelial cells. Collectively, our data indicate that HF diet protects against colitis and CAC risk through gut microbiota and BA metabolites modulating vitamin D targeting pathways. Our data highlights the complex relationship between dietary fat-induced alterations of microbiota-host interactions in IBD/CAC pathophysiology