Pentacyclic triterpenes modulate farnesoid X receptor expression in colonic epithelial cells: Implications for colonic secretory function.

The nuclear bile acid receptor, farnesoid X receptor (FXR), is an important regulator of intestinal and metabolic function. Previous studies suggest that pentacyclic triterpenes (PCTs), a class of plant-derived bioactive phytochemical, can modulate FXR activity and may therefore offer therapeutic benefits. Here, we investigated the effects of a prototypical PCT, hederagenin (HG), on FXR expression, activity, and antisecretory actions in colonic epithelial cells. T84 cells and murine enteroid-derived monolayers were employed to assess HG effects on FXR expression and activity in colonic epithelia. We measured mRNA levels by qRT-PCR and protein by ELISA and immunoblotting. Transepithelial Cl- secretion was assessed as changes in short circuit current in Ussing chambers. We determined HG treatment (5-10 µM) alone did not induce FXR activation but significantly increased expression of the receptor, both in T84 cells and murine enteroid-derived monolayers. This effect was accompanied by enhanced FXR activity, as assessed by FGF-15/19 induction in response to the synthetic, GW4064, or natural FXR agonist, chenodeoxycholic acid. Effects of HG on FXR expression and activity were mimicked by another PCT, oleanolic acid. Furthermore, we found FXR-induced downregulation of cystic fibrosis transmembrane conductance regulator Cl- channels and inhibition of transepithelial Cl- secretion were enhanced in HG-treated cells. These data demonstrate that dietary PCTs have the capacity to modulate FXR expression, activity, and antisecretory actions in colonic epithelial cells. Based on these data, we propose that plants rich in PCTs, or extracts thereof, have excellent potential for development as a new class of "FXR-targeted nutraceuticals".

Novel polyurethane based particulate formulations of infliximab reduce inflammation in DSS induced murine model of colitis - A preliminary study.

Our recent study showed that novel infliximab (INF) loaded polyesterurethane (INF-PU) and INF-PU-PEG particulate formulations reduced inflammation in an in-vitro epithelial inflammation model. In this study we investigated therapeutic potential of novel INF-PU and INF-PU-PEG particulate formulations to reduce inflammation in a dextran sodium sulfate (DSS) induced murine model of colitis. Severity of colitis was assessed by measurement of disease activity index (DAI) score, inflammatory markers (neutrophil infiltration, TNFα) and histological score. Treatment groups orally administered with INF-PU and INF-PU-PEG particulate formulations showed improvement in the clinical signs of colitis, similar to that observed with intraperitoneally administered INF, in both, moderate and severe DSS induced colitis model. This was related to a significant reduction in inflammatory cytokines, resulting in a significant reduction in histological score (ANOVA; p < 0.05), indicative of mucosal healing, a key goal of IBD therapy. This could be attributed to its targeted delivery to the inflamed colon and higher permeation of these particulate formulations across the inflamed colonic mucosa, as observed by the confocal images, resulting in local inhibition of TNFα at its site of production. These promising preliminary results warrant further investigation of orally administered INF and its novel particulate formulations in a wider preclinical study.

The secondary bile acids, ursodeoxycholic acid and lithocholic acid, protect against intestinal inflammation by inhibition of epithelial apoptosis.

Increased epithelial permeability is a key feature of IBD pathogenesis and it has been proposed that agents which promote barrier function may be of therapeutic benefit. We have previously reported the secondary bile acid, ursodeoxycholic acid (UDCA), to be protective in a mouse model of colonic inflammation and that its bacterial metabolism is required for its beneficial effects. The current study aimed to compare the effects of UDCA, LCA, and a non-metabolizable analog of UDCA, 6-methyl-UDCA (6-MUDCA), on colonic barrier function and mucosal inflammation in a mouse model of colonic inflammation. Bile acids were administered daily to C57Bl6 mice by intraperitoneal injection. Colonic inflammation, induced by addition of DSS (2.5%) to the drinking water, was measured as disease activity index (DAI) and histological score. Epithelial permeability and apoptosis were assessed by measuring FITC-dextran uptake and caspase-3 cleavage, respectively. Cecal bile acids were measured by HPLC-MS/MS. UDCA and LCA, but not 6-MUDCA, were protective against DSS-induced increases in epithelial permeability and colonic inflammation. Furthermore, UDCA and LCA inhibited colonic epithelial caspase-3 cleavage both in DSS-treated mice and in an in vitro model of cytokine-induced epithelial injury. HPLC-MS/MS analysis revealed UDCA administration to increase colonic LCA levels, whereas LCA administration did not alter UDCA levels. UDCA, and its primary metabolite, LCA, protect against intestinal inflammation in vivo, at least in part, by inhibition of epithelial apoptosis and promotion of barrier function. These data suggest that clinical trials of UDCA in IBD patients are warranted.

Ursodeoxycholic acid: a promising therapeutic target for inflammatory bowel diseases?

The secondary bile acid ursodeoxycholic acid (UDCA) has long been known to have medicinal properties. As the therapeutically active component of bear bile, it has been used for centuries in traditional Chinese medicine to treat a range of conditions, while manufactured UDCA has been used for decades in Western medicine to treat cholestatic liver diseases. The beneficial qualities of UDCA are thought to be due to its well-established cytoprotective and anti-inflammatory actions. In addition to its established role in treating liver diseases, UDCA is now under investigation for numerous conditions associated with inflammation and apoptosis, including neurological, ocular, metabolic, and cardiovascular diseases. Here, we review the growing evidence base from in vitro and in vivo models to suggest that UDCA may also have a role to play in the therapy of inflammatory bowel diseases.