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Intestinal fibrosis is mainly associated with Crohn's disease and is defined as a progressive and excessive deposition of extracellular matrix components. No specific antifibrotic therapies are available. In this study, we evaluate the antifibrotic effect of a novel 5-ASA analog able to activate the peroxisome proliferator-activated receptor γ, named GED-0507-34 Levo.MethodsColonic fibrosis was induced in 110 C57BL/6 mice by 3 cycles of 2.5% (wt/vol) dextran sulfate sodium administration for 6 weeks. The preventive effects of oral daily GED (30 mg·kg−1·d−1) administration were evaluated using a macroscopic and histological score and also through biological endpoints. Expression of main markers of myofibroblasts activation was determined in transforming growth factor (TGF-β)–stimulated intestinal fibroblasts and epithelial cells.ResultsGED improved macroscopic and microscopic intestinal lesions in dextran sulfate sodium-treated animals and reduced the profibrotic gene expression of Acta2, COL1a1, and Fn1 by 1.48-folds (P < 0.05), 1.93-folds (P < 0.005), and 1.03-fold (P < 0.05), respectively. It reduced protein levels of main markers of fibrosis (α-SMA and Collagen I-II) and the main TGF-β/Smad pathway components. GED also decreased the interleukin-13 and connective tissue growth factor expression by 1.89-folds (P < 0.05) and 2.2-folds (P < 0.005), respectively. GED inhibited TGF-β–induced activation of both fibroblast and intestinal epithelial cell lines, by regulating mRNA expression of α-SMA and fibronectin, and restoring the TGF-β–induced loss of intestinal epithelial cell markers. GED treatment also reduced the TGF-β and ACTA1 expression in primary human intestinal fibroblasts from ulcerative colitis patients.ConclusionsGED ameliorates intestinal fibrosis in dextran sulfate sodium-induced chronic colitis in mice and regulates major profibrotic cellular and molecular mechanisms.

The development of more effective, better tolerated drug treatments for progressive pulmonary fibrosis (of which idiopathic pulmonary fibrosis is the most common and severe form) is a research priority. The peroxisome proliferator-activated receptor gamma (PPAR-γ) is a key regulator of inflammation and fibrosis and therefore represents a potential therapeutic target. However, the use of synthetic PPAR-γ agonists may be limited by their potentially severe adverse effects. In a mouse model of bleomycin (BLM)-induced pulmonary fibrosis, we have demonstrated that the non-racemic selective PPAR-γ modulator GED-0507 is able to reduce body weight loss, ameliorate clinical and histological features of pulmonary fibrosis, and increase survival rate without any safety concerns. Here, we focused on the biomolecular effects of GED-0507 on various inflammatory/fibrotic pathways. We demonstrated that preventive and therapeutic administration of GED-0507 reduced the BLM-induced mRNA expression of several markers of fibrosis, including transforming growth factor (TGF)-β, alpha-smooth muscle actin, collagen and fibronectin as well as epithelial-to-mesenchymal transition (EMT) and expression of mucin 5B. The beneficial effect of GED-0507 on pulmonary fibrosis was confirmed in vitro by its ability to control TGFβ-induced myofibroblast activation in the A549 human alveolar epithelial cell line, the MRC-5 lung fibroblast line, and primary human lung fibroblasts. Compared with the US Food and Drug Administration-approved antifibrotic drugs pirfenidone and nintedanib, GED-0507 displayed greater antifibrotic activity by controlling alveolar epithelial cell dysfunction, EMT, and extracellular matrix remodeling. In conclusion, GED-0507 demonstrated potent antifibrotic properties and might be a promising drug candidate for the treatment of pulmonary fibrosis.

Intestinal fibrosis is characterized by abnormal production and deposition of extracellular matrix (ECM) proteins by activated myofibroblasts. The main progenitor cells of activated myofibroblasts are the fibroblasts and the epithelial cells, the latter through the epithelial-mesenchymal transition (EMT). To evaluate the action of the new PPAR-γ modulator, GED-0507-34 Levo (GED) on the expression of EMT associated and regulatory proteins such as TGF-β, Smad3, E-cadherin, Snail, ZEB1, β-catenin, and GSK-3β, in a mouse model of DSS-induced intestinal fibrosis. Chronic colitis and fibrosis were induced by oral administration of 2.5% DSS (w/v) for 6 weeks. GW9662 (GW), a selective PPAR-γ inhibitor, was also administered by intraperitoneal injection at the dose of 1 mg/kg/day combined with GED treatment. All drugs were administered at the beginning of the second cycle of DSS (day 12). 65 mice were randomly divided into five groups (H2O as controls n = 10, H2O+GED n = 10, DSS n = 15, DSS+GED n = 15, DSS+GED+GW n = 15). The colon was excised for macroscopic examination and histological and morphometric analyses. The level of expression of molecules involved in EMT and fibrosis, like TGF-β, Smad3, E-cadherin, Snail, ZEB1, β-catenin, GSK-3β and PPAR-γ, was assessed by immunohistochemistry, immunofluorescence, western blot and Real Time PCR. GED improved the DSS-induced chronic colitis and fibrosis. GED was able to reduce the expression of the main fibrosis markers (α-SMA, collagen I-III and fibronectin) as well as the pivotal pro-fibrotic molecules IL-13, TGF-β and Smad3, while it increased the anti-fibrotic PPAR-γ. All these GED effects were nullified by co-administration of GW with GED. Furthermore, GED was able to normalize the expression levels of E-cadherin and β-catenin and upregulated GSK-3β, that are all known to be involved both in EMT and fibrosis. The DSS-induced intestinal fibrosis was improved by the new PPAR-γ modulator GED-0507-34 Levo through the modulation of EMT mediators and pro-fibrotic molecules and through GSK-3β induction.

Lactase (LCT) deficiency affects approximately 75% of the world's adult population and may lead to lactose malabsorption and intolerance. Currently, the regulation of LCT gene expression remains poorly known. Peroxisome proliferator activator receptorγ (PPARγ) is a key player in carbohydrate metabolism. While the intestine is essential for carbohydrate digestion and absorption, the role of PPARγ in enterocyte metabolic functions has been poorly investigated. This study aims at characterizing PPARγ target genes involved in intestinal metabolic functions. In microarray analysis, the LCT gene was the most upregulated by PPARγ agonists in Caco‐2 cells. We confirmed that PPARγ agonists were able to increase the expression and activity of LCT both in vitro and in vivo in the proximal small bowel of rodents. The functional response element activated by PPARγ was identified in the promoter of the human LCT gene. PPARγ modulation was able to improve symptoms induced by lactose‐enriched diet in weaned rats. Our results demonstrate that PPARγ regulates LCT expression, and suggest that modulating intestinal PPARγ activity might constitute a new therapeutic strategy for lactose malabsorption. Synopsis The activation of the nuclear receptor Peroxisome Proliferator‐Activated Receptor gamma (PPARγ) increases the expression and activity of the lactase (LCT) enzyme and improves the biological disturbances induced by a lactose‐enriched diet in rodents. Synthetic and natural PPARγ agonist ligands are able to increase the expression and activity of LCT in Caco‐2 cells as well as in the proximal small intestine of mice and rats. Weaned rats fed with a lactose‐enriched diet developed diarrhea associated with an increased fermentation activity of undigested lactose, which are both significantly improved by a PPARγ agonist. Modulating intestinal PPARγ activity might improve the symptoms associated with hypolactasia and lactose malabsorption in humans. Graphical Abstract The activation of the nuclear receptor Peroxisome Proliferator‐Activated Receptor gamma (PPARγ) increases the expression and activity of the lactase (LCT) enzyme and improves the biological disturbances induced by a lactose‐enriched diet in rodents.

A concomitant action of multiple profibrotic mediators appears crucial in the development and progression of fibrosis. Sphingosine kinase/sphingosine 1 phosphate and transforming growth factor-β/Smads pathways are both involved in pathogenesis of fibrosis in several organs by controlling differentiation of fibroblasts to myofibroblasts and the epithelial to-mesenchymal transition. However, their direct involvement in chronic colitis-associated fibrosis it is not yet known. In this study we evaluated the immunohistochemical expression of some proteins implicated in sphingosine kinase/sphingosine 1 phosphate and transforming growth factor-β/Smads pathways in Dextrane Sodium Sulphate (DSS)-induced colorectal fibrosis in mice. Compared to control mice, DSS-induced chronic colitis mice developed a marked intestinal fibrosis associated with a concomitant overexpression of TGF-β, p-Smad3, α-SMA, collagen I-III, SPHK1, RhoA, PI3K, Akt, p-Akt, p-mTOR. This study highlights the relationship between the two pathways and the possible role of SPHK1 in the intestinal fibrosis.  These results, if confirmed by in vitro studies, may have important clinical implications in the development of new therapeutical approaches in inflammatory bowel disease.

IntroductionIrritable bowel syndrome (IBS) is a prevalent and challenging condition with limited therapeutic options. In order to assess the potential of CG as an alternative for IBS management, we performed an array of preclinical studies to evaluate the roles of Chitin-Glucan (CG), a safe dietary prebiotic, on the IBS physiopathological mechanisms, such as visceral analgesia, intestinal inflammation, barrier function.MethodsVisceral pain was recorded in a rat model with colon hypersensitivity induced by TNBS. Intracolonic pressure was assessed in animals receiving CG at a human equivalent dose (HED) of 1.5 g/d or 3 g/d and compared to negative- (tap water) and positive- (phloroglucinol) control groups. The anti-inflammatory effect of CG was evaluated using clinical and histological scores in DSS-induced mice. HT-29 cells were treated with CG to evaluate changes related to analgesia, inflammation and barrier. Molecular modelling explored the ability of CG to chelate microbial pathogenic lipids.ResultsOral administration of CG in rats or mice was well tolerated without diarrhea or inflammation evaluated at histologic and molecular levels. CG at 3 g/d HED significantly decreased visceral perception by 14% after 2 weeks (p<0.01) and reduced inflammation by 50% promoting mucosal regeneration in DSS-induced colitis mice. CG at 1.5 g/d HED reduced visceral pain perception by 20% in TNBS-colitis induced rats with CG at 1.5 g/d HED after 5 weeks (p<0.01). At 3 g/d HED, this analgesic effect was superior to phloroglucinol with a faster onset of action and a 50% inhibition of pain perception (p<0.0001). The molecular mechanisms of CG involved at least in part a significant induction of MOR, CB2 receptor, IL-10 and a significant decrease of pro-inflammatory cytokines IL-1β and IL-8 mRNA. CG also significantly up-regulated barrier-related genes like muc5AC, claudin-2 and ZO-2. CG molecular modelling revealed a new property of the molecule as a chelator of microbial pathogenic lipids.ConclusionCG decreased visceral perception and intestinal inflammation through master genes regulation and direct binding of microbial products, giving evidence-based CG as a promising treatment for patients with IBS or IBS-like symptoms.

The hexosamine biosynthetic pathway (HBP) integrates glucose, amino acids, fatty acids and nucleotides metabolisms for uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) synthesis. UDP-GlcNAc is the nucleotide sugar donor for O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) processes. O-GlcNAc transferase (OGT) is the enzyme which transfers the N-acetylglucosamine (O-GlcNAc) residue onto target proteins. Several studies previously showed that glucose metabolism dysregulations associated with obesity, diabetes or cancer correlated with an increase of OGT expression and global O-GlcNAcylation levels. Moreover, these diseases present an increased activation of the nutrient sensing mammalian target of rapamycin (mTOR) pathway. Other works demonstrate that mTOR regulates protein O-GlcNAcylation in cancer cells through stabilization of OGT. In this context, we studied the cross-talk between these two metabolic sensors in vivo in obese mice predisposed to diabetes and in vitro in normal and colon cancer cells. We report that levels of OGT and O-GlcNAcylation are increased in obese mice colon tissues and colon cancer cells and are associated with a higher activation of mTOR signaling. In parallel, treatments with mTOR regulators modulate OGT and O-GlcNAcylation levels in both normal and colon cancer cells. However, deregulation of O-GlcNAcylation affects mTOR signaling activation only in cancer cells. Thus, a crosstalk exists between O-GlcNAcylation and mTOR signaling in contexts of metabolism dysregulation associated to obesity or cancer.

ObjectiveMesenteric fat hyperplasia is a hallmark of Crohn's disease (CD), and C reactive protein (CRP) is correlated with disease activity. The authors investigated whether mesenteric adipocytes may be a source of CRP in CD and whether inflammatory and bacterial triggers may stimulate its production by adipocytes.DesignCRP expression in the mesenteric and subcutaneous fats of patients with CD and the correlation between CRP plasma concentrations and mesenteric messenger RNA (mRNA) levels were assessed. The impact of inflammatory and bacterial challenges on CRP synthesis was tested using an adipocyte cell line. Bacterial translocation to mesenteric fat was studied in experimental models of colitis and ileitis and in patients with CD.ResultsCRP expression was increased in the mesenteric fat of patients with CD, with mRNA levels being 80±40 (p<0.05) and 140±65 (p=0.04) times higher than in the mesenteric fat of patients with ulcerative colitis and in the subcutaneous fat of the same CD subjects, respectively, and correlated with plasma levels. Escherichia coli (1230±175-fold, p<0.01), lipopolysaccharide (26±0.5-fold, p<0.01), tumour necrosis factor α (15±0.3-fold, p<0.01) and interleukin-6 (10±0.7-fold, p<0.05) increased CRP mRNA levels in adipocyte 3T3-L1 cells. Bacterial translocation to mesenteric fat occurred in 13% and 27% of healthy and CD subjects, respectively, and was increased in experimental colitis and ileitis. Human mesenteric adipocytes constitutively expressed mRNA for TLR2, TLR4, NOD1 and NOD2.ConclusionMesenteric fat is an important source of CRP in CD. CRP production by mesenteric adipocytes may be triggered by local inflammation and bacterial translocation to mesenteric fat, providing a mechanism whereby mesenteric fat hyperplasia may contribute to inflammatory response in CD.

The therapeutic management of Crohn’s disease (CD), a chronic relapsing–remitting inflammatory bowel disease (IBD), is highly challenging. Surgical resection is sometimes a necessary procedure even though it is often associated with postoperative recurrences (PORs). Tofacitinib, an orally active small molecule Janus kinase inhibitor, is an anti-inflammatory drug meant to limit PORs in CD. Whereas bidirectional interactions between the gut microbiota and the relevant IBD drug are crucial, little is known about the impact of tofacitinib on the gut microbiota. The HLA-B27 transgenic rat is a good preclinical model used in IBD research, including for PORs after ileocecal resection (ICR). In the present study, we used shotgun metagenomics to first delineate the baseline composition and determinants of the fecal microbiome of HLA-B27 rats and then to evaluate the distinct impact of either tofacitinib treatment, ileocecal resection or the cumulative effect of both interventions on the gut microbiota in these HLA-B27 rats. The results confirmed that the microbiome of the HLA-B27 rats was fairly different from their wild-type littermates. We demonstrated here that oral treatment with tofacitinib does not affect the gut microbial composition of HLA-B27 rats. Of note, we showed that ICR induced an intense loss of bacterial diversity together with dramatic changes in taxa relative abundances. However, the oral treatment with tofacitinib neither modified the alpha-diversity nor exacerbated significant modifications in bacterial taxa induced by ICR. Collectively, these preclinical data are rather favorable for the use of tofacitinib in combination with ICR to address Crohn’s disease management when considering microbiota.