An Overview of the Influence of Breastfeeding on the Development of Inflammatory Bowel Disease.

The first 1000 days of life is a critical period that contributes significantly to the programming of an individual's future health. Among the many changes that occur during this period early in life, there is growing evidence that the establishment of healthy gut microbiota plays an important role in the prevention of both short- and long-term health problems. Numerous publications suggest that the quality of the gut microbiota colonisation depends on several dietary factors, including breastfeeding. In this respect, a relationship between breastfeeding and the risk of inflammatory bowel disease (IBD) has been suggested. IBDs are chronic intestinal diseases, and perinatal factors may be partly responsible for their onset. We review the existence of links between breastfeeding and IBD based on experimental and clinical studies. Overall, despite encouraging experimental data in rodents, the association between breastfeeding and the development of IBD remains controversial in humans, partly due to the considerable heterogeneity between clinical studies. The duration of exclusive breastfeeding is probably decisive for its lasting effect on IBD. Thus, specific improvements in our knowledge could support dietary interventions targeting the gut microbiome, such as the early use of prebiotics, probiotics or postbiotics, in order to prevent the disease.

Reactivation of a somatic errantivirus and germline invasion in Drosophila ovaries.

Most Drosophila transposable elements are LTR retrotransposons, some of which belong to the genus Errantivirus and share structural and functional characteristics with vertebrate endogenous retroviruses. Like endogenous retroviruses, it is unclear whether errantiviruses retain some infectivity and transposition capacity. We created conditions where control of the Drosophila ZAM errantivirus through the piRNA pathway was abolished leading to its de novo reactivation in somatic gonadal cells. After reactivation, ZAM invaded the oocytes and severe fertility defects were observed. While ZAM expression persists in the somatic gonadal cells, the germline then set up its own adaptive genomic immune response by producing piRNAs against the constantly invading errantivirus, restricting invasion. Our results suggest that although errantiviruses are continuously repressed by the piRNA pathway, they may retain their ability to infect the germline and transpose, thus allowing them to efficiently invade the germline if they are expressed.

The PPARγ-dependent effect of flavonoid luteolin against damage induced by the chemotherapeutic irinotecan in human intestinal cells.

Irinotecan (CPT-11) is one of the main agents used to treat colorectal cancer; unfortunately, it is associated with increased intestinal mucositis developing. Luteolin has been shown to prevent damage induced by this chemotherapeutic in mice; thus, in this research, we have investigated luteolin's action mechanism in human intestinal epithelial cells. The potential of luteolin in reducing inflammation and oxidative stress induced by irinotecan in Caco-2 cells was evaluated by PCR through mRNA expression of inflammatory and oxidative genes and by ELISA at the protein level. To assess whether luteolin's ability to control irinotecan-induced damage occurs in a PPARγ dependent manner, experiments were performed on PPARγ downregulated cells. Irinotecan downregulated PPARγ expression and upregulated inflammatory and oxidative genes, while luteolin upregulated PPARγ, HO-1, SOD and decreased expression of IL-1ß and iNOS. Interestingly, when the cells were co-stimulated with luteolin and irinotecan, the flavonoid reversed the inflammation and oxidative imbalance evoked by the chemotherapeutic. However, when these experiments were performed in cells downregulated for PPARγ, luteolin lost the capacity to increase PPARγ and reverse the effect of irinotecan in all tested genes, except by IL-1ß. The present study showed that the protective effect of luteolin against irinotecan is PPARγ dependent.

A polarized nucleus-cytoskeleton-ECM connection in migrating cardioblasts controls heart tube formation in Drosophila.

The formation of the cardiac tube is a remarkable example of complex morphogenetic processes conserved from invertebrates to humans. It involves coordinated collective migration of contralateral rows of cardiac cells. The molecular processes underlying the specification of cardioblasts (CBs) prior to migration are well established and significant advances have been made in understanding the process of lumen formation. However, the mechanisms of collective cardiac cells migration remain elusive. Here, we have identified CAP and MSP300 as novel actors involved during CB migration. They both exhibit highly similar temporal and spatial expression patterns in Drosophila migrating cardiac cells, and are necessary for the correct number and alignment of CBs, a prerequisite for the coordination of their collective migration. Our data suggest that CAP and MSP300 are part of a protein complex linking focal adhesion sites to nuclei via the actin cytoskeleton that maintains post-mitotic state and correct alignment of CBs.

Gelsolin and dCryAB act downstream of muscle identity genes and contribute to preventing muscle splitting and branching in Drosophila.

A combinatorial code of identity transcription factors (iTFs) specifies the diversity of muscle types in Drosophila. We previously showed that two iTFs, Lms and Ap, play critical role in the identity of a subset of larval body wall muscles, the lateral transverse (LT) muscles. Intriguingly, a small portion of ap and lms mutants displays an increased number of LT muscles, a phenotype that recalls pathological split muscle fibers in human. However, genes acting downstream of Ap and Lms to prevent these aberrant muscle feature are not known. Here, we applied a cell type specific translational profiling (TRAP) to identify gene expression signatures underlying identity of muscle subsets including the LT muscles. We found that Gelsolin (Gel) and dCryAB, both encoding actin-interacting proteins, displayed LT muscle prevailing expression positively regulated by, the LT iTFs. Loss of dCryAB function resulted in LTs with irregular shape and occasional branched ends also observed in ap and lms mutant contexts. In contrast, enlarged and then split LTs with a greater number of myonuclei formed in Gel mutants while Gel gain of function resulted in unfused myoblasts, collectively indicating that Gel regulates LTs size and prevents splitting by limiting myoblast fusion. Thus, dCryAB and Gel act downstream of Lms and Ap and contribute to preventing LT muscle branching and splitting. Our findings offer first clues to still unknown mechanisms of pathological muscle splitting commonly detected in human dystrophic muscles and causing muscle weakness.

Predictive Value of the Residual SYNTAX Score in Patients With Cardiogenic Shock.

BACKGROUND: In hemodynamically stable patients, complete revascularization (CR) following percutaneous coronary intervention (PCI) is associated with a better prognosis in chronic and acute coronary syndromes. OBJECTIVES: This study sought to assess the extent, severity, and prognostic value of remaining coronary stenoses following PCI, by using the residual SYNTAX score (rSS), in patients with cardiogenic shock (CS) related to myocardial infarction (MI). METHODS: The CULPRIT-SHOCK (Culprit Lesion Only Percutaneous Coronary Intervention [PCI] Versus Multivessel PCI in Cardiogenic Shock) trial compared a multivessel PCI (MV-PCI) strategy with a culprit lesion-only PCI (CLO-PCI) strategy in patients with multivessel coronary artery disease who presented with MI-related CS. The rSS was assessed by a central core laboratory. The study group was divided in 4 subgroups according to tertiles of rSS of the participants, thereby isolating patients with an rSS of 0 (CR). The predictive value of rSS for the 30-day primary endpoint (mortality or severe renal failure) and for 30-day and 1-year mortality was assessed using multivariate logistic regression. RESULTS: Among the 587 patients with an rSS available, the median rSS was 9.0 (interquartile range: 3.0 to 17.0); 102 (17.4%), 100 (17.0%), 196 (33.4%), and 189 (32.2%) patients had rSS = 0, 0 < rSS ≤5, 5 < rSS ≤14, and rSS >14, respectively. CR was achieved in 75 (25.2%; 95% confidence interval [CI]: 20.3% to 30.5%) and 27 (9.3%; 95% CI: 6.2% to 13.3%) of patients treated using the MV-PCI and CLO-PCI strategies, respectively. After multiple adjustments, rSS was independently associated with 30-day mortality (adjusted odds ratio per 10 units: 1.49; 95% CI: 1.11 to 2.01) and 1-year mortality (adjusted odds ratio per 10 units: 1.52; 95% CI: 1.11 to 2.07). CONCLUSIONS: Among patients with multivessel disease and MI-related CS, CR is achieved only in one-fourth of the patients treated using an MV-PCI strategy. and the residual SYNTAX score is independently associated with early and late mortality.

The Class I HDAC Inhibitor, MS-275, Prevents Oxaliplatin-Induced Chronic Neuropathy and Potentiates Its Antiproliferative Activity in Mice.

Oxaliplatin, the first-line chemotherapeutic agent against colorectal cancer (CRC), induces peripheral neuropathies, which can lead to dose limitation and treatment discontinuation. Downregulation of potassium channels, which involves histone deacetylase (HDAC) activity, has been identified as an important tuner of acute oxaliplatin-induced hypersensitivity. MS-275, a class I histone deacetylase inhibitor (HDACi), prevents acute oxaliplatin-induced peripheral neuropathy (OIPN). Moreover, MS-275 exerts anti-tumor activity in several types of cancers, including CRC. We thus hypothesized that MS-275 could exert both a preventive effect against OIPN and potentially a synergistic effect combined with oxaliplatin against CRC development. We first used RNAseq to assess transcriptional changes occurring in DRG neurons from mice treated by repeated injection of oxaliplatin. Moreover, we assessed the effects of MS-275 on chronic oxaliplatin-induced peripheral neuropathy development in vivo on APCMin/+ mice and on cancer progression when combined with oxaliplatin, both in vivo on APCMin/+ mice and in a mouse model of an orthotopic allograft of the CT26 cell line as well as in vitro in T84 and HT29 human CRC cell lines. We found 741 differentially expressed genes (DEGs) between oxaliplatin- and vehicle-treated animals. While acute OIPN is known as a channelopathy involving HDAC activity, chronic OIPN exerts weak ion channel transcriptional changes and no HDAC expression changes in peripheral neurons from OIPN mice. However, MS-275 prevents the development of sensory neuropathic symptoms induced by repeated oxaliplatin administration in APCMin/+ mice. Moreover, combined with oxaliplatin, MS-275 also exerts synergistic antiproliferative and increased survival effects in CT26-bearing mice. Consistently, combined drug associations exert synergic apoptotic and cell death effects in both T84 and HT29 human CRC cell lines. Our results strongly suggest combining oxaliplatin and MS-275 administration in CRC patients in order to potentiate the antiproliferative action of chemotherapy, while preventing its neurotoxic effect.

Contribution of the Gut Microbiota in P28GST-Mediated Anti-Inflammatory Effects: Experimental and Clinical Insights.

An original immuno-regulatory strategy against inflammatory bowel diseases based on the use of 28 kDa glutathione S-transferase (P28GST), a unique schistosome protein, was recently proposed. Improvement of intestinal inflammation occurs through restoration of the immunological balance between pro-inflammatory T-helper 1 (Th1) responses and both T-helper 2 (Th2) and regulatory responses. However, detailed mechanisms explaining how P28GST prevents colitis and promotes gut homeostasis remain unknown. Considering the complex interplay between the adaptive and innate immune system and the intestinal microbiota, we raised the question of the possible role of the microbial ecosystem in the anti-inflammatory effects mediated by the helminth-derived P28GST protein. We first analyzed, by 16S rRNA sequencing, the bacterial profiles of mice fecal microbiota at several time points of the P28GST-immunomodulation period prior to trinitrobenzene sulfonic acid (TNBS)-colitis. The influence of gut microbiota in the P28GST-mediated anti-inflammatory effects was then assessed by fecal microbiota transplantation experiments from P28GST-immunized mice to either conventional or microbiota depleted naïve recipient mice. Finally, the experimental data were supplemented by the temporal fecal microbiota compositions of P28GST-treated Crohn's disease patients from a pilot clinical study (NCT02281916). The P28GST administration slightly modulated the diversity and composition of mouse fecal microbiota while it significantly reduced experimental colitis in mice. Fecal microbiota transplantation experiments failed to restore the P28GST-induced anti-inflammatory effects. In Crohn's disease patients, P28GST also induced slight changes in their overall fecal bacterial composition. Collectively, these results provide key elements in both the anti-inflammatory mechanisms and the safe therapeutic use of immunomodulation with such promising helminth-derived molecules.

Nucleotide-binding oligomerization domain 1 (NOD1) modulates liver ischemia reperfusion through the expression adhesion molecules.

BACKGROUND & AIMS: In liver transplantation, organ shortage leads to the use of marginal grafts that are more susceptible to ischemia-reperfusion (IR) injury. We identified nucleotide-binding oligomerization domain 1 (NOD1) as an important modulator of polymorphonuclear neutrophil (PMN)-induced liver injury, which occurs in IR. Herein, we aimed to elucidate the role of NOD1 in IR injury, particularly focusing on its effects on the endothelium and hepatocytes. METHOD: Nod1 WT and KO mice were treated with NOD1 agonists and subjected to liver IR. Expression of adhesion molecules was analyzed in total liver, isolated hepatocytes and endothelial cells. Interactions between PMNs and hepatocytes were studied in an ex vivo co-culture model using electron microscopy and lactate dehydrogenase levels. We generated NOD1 antagonist-loaded nanoparticles (np ALINO). RESULTS: NOD1 agonist treatment increased liver injury, PMN tissue infiltration and upregulated ICAM-1 and VCAM-1 expression 20 hours after reperfusion. NOD1 agonist treatment without IR increased expression of adhesion molecules (ICAM-1, VCAM-1) in total liver and more particularly in WT hepatocytes, but not in Nod1 KO hepatocytes. This induction is dependent of p38 and ERK signaling pathways. Compared to untreated hepatocytes, a NOD1 agonist markedly increased hepatocyte lysis in co-culture with PMNs as shown by the increase of lactate dehydrogenase in supernatants. Interaction between hepatocytes and PMNs was confirmed by electron microscopy. In a mouse model of liver IR, treatment with np ALINO significantly reduced the area of necrosis, aminotransferase levels and ICAM-1 expression. CONCLUSION: NOD1 regulates liver IR injury through induction of adhesion molecules and modulation of hepatocyte-PMN interactions. NOD1 antagonist-loaded nanoparticles reduced liver IR injury and provide a potential approach to prevent IR, especially in the context of liver transplantation. LAY SUMMARY: Nucleotide-binding oligomerization domain 1 (NOD1) is as an important modulator of polymorphonuclear neutrophil (PMN)-induced liver injury, which occurs in ischemia-reperfusion. Here, we show that the NOD1 pathway targets liver adhesion molecule expression on the endothelium and on hepatocytes through p38 and ERK signaling pathways. The early increase of adhesion molecule expression after reperfusion emphasizes the importance of adhesion molecules in liver injury. In this study we generated nanoparticles loaded with NOD1 antagonist. These nanoparticles reduced liver necrosis by reducing PMN liver infiltration and adhesion molecule expression.

Peroxisome proliferator-activated receptor gamma (PPARγ) regulates lactase expression and activity in the gut.

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.

The Expression of the Short Isoform of Thymic Stromal Lymphopoietin in the Colon Is Regulated by the Nuclear Receptor Peroxisome Proliferator Activated Receptor-Gamma and Is Impaired during Ulcerative Colitis.

The etiology of inflammatory bowel diseases remains largely unknown. We previously demonstrated that the expression of the peroxisome proliferator activated receptor-gamma (PPARγ) is downregulated in colonic epithelial cells of patients with ulcerative colitis (UC). PPARγ is a nuclear receptor that modulates inflammation. We hypothesized that its deficiency may play a role in the loss of intestinal homeostasis through the control of immunomodulatory factors. We found that thymic stromal lymphopoietin (TSLP), an epithelial cytokine with pleiotropic functions, is regulated by PPARγ. While this cytokine possesses two isoforms, only the short form (sfTSLP) was regulated by PPARγ. sfTSLP mRNA expression was decreased both in PPARγ knock-down Caco2 cells and cells treated with PPARγ antagonist, whereas PPARγ agonists induced the expression of sfTSLP in Caco2 and T-84 cells. The response element activated by PPARγ was identified in the promoter of the sfTSLP gene by chromatin immunoprecipitation and gene reporter assays. The expression of sfTSLP was significantly decreased in the colonic mucosa of UC patients compared to controls and was correlated with PPARγ expression. Our results identified sfTSLP as a new PPARγ-target gene and support the hypothesis that, in UC, PPARγ deficiency in colonic mucosa could play a role in the loss of intestinal tolerance through an impaired sfTSLP expression.

Novel PPARγ Modulator GED-0507-34 Levo Ameliorates Inflammation-driven Intestinal Fibrosis.

BACKGROUND: 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. METHODS: Colonic 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-ß)-stimulated intestinal fibroblasts and epithelial cells. RESULTS: GED 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-ß/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-ß-induced activation of both fibroblast and intestinal epithelial cell lines, by regulating mRNA expression of α-SMA and fibronectin, and restoring the TGF-ß-induced loss of intestinal epithelial cell markers. GED treatment also reduced the TGF-ß and ACTA1 expression in primary human intestinal fibroblasts from ulcerative colitis patients. CONCLUSIONS: GED ameliorates intestinal fibrosis in dextran sulfate sodium-induced chronic colitis in mice and regulates major profibrotic cellular and molecular mechanisms.

TRAP-rc, Translating Ribosome Affinity Purification from Rare Cell Populations of Drosophila Embryos.

Measuring levels of mRNAs in the process of translation in individual cells provides information on the proteins involved in cellular functions at a given point in time. The protocol dubbed Translating Ribosome Affinity Purification (TRAP) is able to capture this mRNA translation process in a cell-type-specific manner. Based on the affinity purification of polysomes carrying a tagged ribosomal subunit, TRAP can be applied to translatome analyses in individual cells, making it possible to compare cell types during the course of developmental processes or to track disease development progress and the impact of potential therapies at molecular level. Here we report an optimized version of the TRAP protocol, called TRAP-rc (rare cells), dedicated to identifying engaged-in-translation RNAs from rare cell populations. TRAP-rc was validated using the Gal4/UAS targeting system in a restricted population of muscle cells in Drosophila embryos. This novel protocol allows the recovery of cell-type-specific RNA in sufficient quantities for global gene expression analytics such as microarrays or RNA-seq. The robustness of the protocol and the large collections of Gal4 drivers make TRAP-rc a highly versatile approach with potential applications in cell-specific genome-wide studies.

Intestinal steroidogenesis.

Steroids are fundamental hormones that control a wide variety of physiological processes such as metabolism, immune functions, and sexual characteristics. Historically, steroid synthesis was considered a function restricted to the adrenals and the gonads. In the past 20 years, a significant number of studies have demonstrated that steroids could also be synthesized or metabolized by other organs. According to these studies, the intestine appears to be a major source of de novo produced glucocorticoids as well as a tissue capable of producing and metabolizing sex steroids. This finding is based on the detection of steroidogenic enzyme expression as well as the presence of bioactive steroids in both the rodent and human gut. Within the intestinal mucosa, the intestinal epithelial cell layer is one of the main cellular sources of steroids. Glucocorticoid synthesis regulation in the intestinal epithelial cells is unique in that it does not involve the classical positive regulator steroidogenic factor-1 (SF-1) but a closely related homolog, namely the liver receptor homolog-1 (LRH-1). This local production of immunoregulatory glucocorticoids contributes to intestinal homeostasis and has been linked to pathophysiology of inflammatory bowel diseases. Intestinal epithelial cells also possess the ability to metabolize sex steroids, notably estrogen; this mechanism may impact colorectal cancer development. In this review, we contextualize and discuss what is known about intestinal steroidogenesis and regulation as well as the key role these functions play both in physiological and pathological conditions.

Intestinal steroidogenesis controls PPARγ expression in the colon and is impaired during ulcerative colitis.

BACKGROUND AND AIMS: Immune tolerance breakdown during UC involves the peroxisome proliferator-activated receptor-γ (PPARγ), a key factor in mucosal homoeostasis and the therapeutic target of 5-aminosalycilates, which expression is impaired during UC. Here we assess the impact of glucocorticoids (GCs) on PPARγ expression, focusing especially on extra-adrenal cortisol production by colonic epithelial cells (CECs). METHODS: Activation of PPARγ in the colon was evaluated using transgenic mice for the luciferase gene under PPAR control (peroxisome proliferator response element-luciferase mice). Protein and mRNA expression of PPARγ were evaluated with colon fragments and purified CEC from mice. Cortisol production and steroidogenic factor expression were quantified in human CEC of patients with UC and those of controls. Gene expression knockdown by short hairpin RNA in Caco-2 cells was used for functional studies. RESULTS: GCs were able to raise luciferase activity in peroxisome proliferator response element-luciferase mice. In the mice colons and Caco-2 cells, PPARγ expression was increased either with GCs or with an inducer of steroidogenesis and then decreased after treatment with a steroidogenesis inhibitor. Cortisol production and steroidogenic factor expression, such as liver receptor homologue-1 (LRH-1), were decreased in CEC isolated from patients with UC, directly correlating with PPARγ impairment. Experiments on Caco-2 cells lacking LRH-1 expression confirmed that LRH-1 controls PPARγ expression by regulating GC synthesis in CEC. CONCLUSIONS: These results demonstrate cortisol control of PPARγ expression in CEC, highlighting cortisol production deficiency in colonocytes as a key molecular event in the pathophysiology of UC.

Regulation of DNA methylation patterns by CK2-mediated phosphorylation of Dnmt3a.

DNA methylation is a central epigenetic modification that is established by de novo DNA methyltransferases. The mechanisms underlying the generation of genomic methylation patterns are still poorly understood. Using mass spectrometry and a phosphospecific Dnmt3a antibody, we demonstrate that CK2 phosphorylates endogenous Dnmt3a at two key residues located near its PWWP domain, thereby downregulating the ability of Dnmt3a to methylate DNA. Genome-wide DNA methylation analysis shows that CK2 primarily modulates CpG methylation of several repeats, most notably of Alu SINEs. This modulation can be directly attributed to CK2-mediated phosphorylation of Dnmt3a. We also find that CK2-mediated phosphorylation is required for localization of Dnmt3a to heterochromatin. By revealing phosphorylation as a mode of regulation of de novo DNA methyltransferase function and by uncovering a mechanism for the regulation of methylation at repetitive elements, our results shed light on the origin of DNA methylation patterns.

Switching invariant natural killer T (iNKT) cell response from anticancerous to anti-inflammatory effect: molecular bases.

Since the discovery in 1995 of α-galactosylceramide 1 (α-GalCer), also known as KRN7000,1 hundreds of compounds have been synthesized in order to activate invariant natural killer T (iNKT) cells. Such keen interest for this lymphocyte cell type is due to its ability to produce different cytokines that bias the immune response toward a Th1 or Th2 profile. Thus, an understanding of the immune polarization mechanism via iNKT activation may pave the way toward new therapeutics in various domains including cancer and infectious and autoimmune diseases. In this review, we propose an up-to-date analysis of iNKT activators associated with a structure-activity relationship (SAR) study aimed at complementing available reviews by highlighting molecular bases for a selective immune response.

Functional polymorphisms in the regulatory regions of the VNN1 gene are associated with susceptibility to inflammatory bowel diseases.

BACKGROUND: Vanin-1 is an epithelial pantetheinase, which regulates intestinal inflammation in mouse. We investigated whether human VNN1 levels could be associated to the susceptibility to inflammatory bowel diseases (IBD) and explored the participation of PPARg to these processes. METHODS: We studied VNN1 expression in colon biopsies from IBD patients. We investigated polymorphisms in the regulatory regions of the VNN1 gene and examined their genetic association with the disease. Functional relevance of these single-nucleotide polymorphisms (SNPs) was assayed, and we tested PPARg in nuclear complexes associated with specific VNN1 polymorphic sequences. In mouse, we examined Vanin-1 expression in gut and feces during dextran sulfate sodium-induced colitis and assayed the effect of PPARg on Vanin-1 regulation. RESULTS: VNN1 is expressed by enterocytes and is upregulated in IBD. Three SNPs are statistically associated to IBD. The regions containing these SNPs specifically bind nuclear complexes and are correlated with the VNN1 transcript abundance in colon in an allele-dependent manner. One rare SNP is associated to severe ulcerative colitis with strong VNN1 and dropped PPARg levels. PPARg is involved in nuclear complexes that bound to VNN1 regulatory sites. Similarly, Vanin-1 is tightly regulated in the mouse gut in normal and colitis conditions and PPARg regulates its expression. CONCLUSIONS: VNN1 is a marker for IBD. Polymorphic positions in the VNN1 locus are direct targets for nuclear factors that might regulate the level of VNN1 in colon, and this could be linked to IBD susceptibility. It is hoped that modulating locally VNN1 expression or activity can be exploited to develop future therapeutic strategies against IBD.

The 5-aminosalicylic acid antineoplastic effect in the intestine is mediated by PPARγ.

Epidemiological evidences suggested that 5-aminosalicylic acid (5-ASA) therapy may prevent the development of colorectal cancer in inflammatory bowel disease patients. Our aim is to investigate whether peroxisome proliferator-activated receptor-γ (PPARγ) mediates the antineoplastic effects of 5-ASA. HT-29 and Caco-2 cells were treated by 5-ASA, rosiglitazone (PPARγ ligand) or etoposide (anticarcinogenic drug). Epithelial cell growth, proliferation and apoptosis were assessed by cell count, Ki-67 staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, respectively. The antineoplastic effect of 5-ASA was evaluated in a xenograft tumor model in SCID mice and in azoxymethane (AOM)-induced colon carcinogenesis in A/JOlaHsd mice. The role of PPARγ was examined by administration of PPARγ antagonist, GW9662 and in PPAR knockdown cells. Compared with untreated cells, treatment of HT-29 cells by 5-ASA inhibited significantly cell growth and cell proliferation (respectively, 60% and 63%) and induced apoptosis in 75% of cells. These effects were abolished by co-treatment with GW9662 and blunted in PPAR knockdown cells. Contrarily to etoposide, similar inhibitory effects of GW9662 were obtained in HT-29 cells treated with rosiglitazone. In the xenograft model, GW9662 abolished the therapeutic effect of 5-ASA, which decreased tumor weight and volume by 80% in SCID mice compared with untreated mice. In A/JOlaHsd mice, 5-ASA suppressed colon carcinogenesis by decreasing the number of aberrant crypt foci (75%) and aberrant crypts (22%) induced by AOM treatment with an absence of 5-ASA response after GW9662 administration. In conclusion, 5-ASA exerts potent antineoplastic effects that are mediated through PPARγ. These data provide new rational for designing more effective and safe antineoplastic PPARγ ligands with topical effects.

PPAR-gamma in ulcerative colitis: a novel target for intervention.

Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor, originally described in adipose tissue, that controls the expression of a large number of regulatory genes in lipid metabolism and insulin sensitization. Well known by endocrinologists, thiazolidinediones (TZDs) are classical PPARγ synthetic agonists which were currently used as insulin-sensitizing agents in the treatment of type 2 diabetes. While the clinical benefits of TZDs in treating metabolic disorders have been clearly demonstrated, new studies performed in animal models of colitis and in patients with ulcerative colitis have also revealed the key roles of PPARγ activation in the regulation of inflammation and immune response, notably in the colon through epithelial cells. During inflammation, PPAR acts directly to negatively regulate gene expression of proinflammatory genes in a ligand-dependent manner by antagonizing the activities of other transcription factors such as members of the NF-κB and AP-1 families. A major mechanism that underlies the ability of PPARs to interfere with the activities of these transcription factors has been termed transrepression. PPARγ acts by inhibiting signaldependent transcription factors that mediate inflammatory programs of gene activation. However, due to safety issues concerning particularly the greater risk of myocardial infarction, use of TZDs has been severely limited for the treatment of type 2 diabetes and/or inflammatory diseases, justifying the development of a new family of PPARγ agonists with major transrepressive effects and without toxicity. By the demonstration that the anti-inflammatory effects of 5- aminosalicylic acid (5-ASA) in patients with ulcerative colitis were mediated by PPARγ activation, several molecules having 5-ASA similarities have been developed and screened leading to the selection of a aminophenyl-alpha-methoxypropionic acids named GED-0507-34-Levo (GED). This compound activating PPARγ has 100-to 150-fold higher anti-inflammatory activity than 5-ASA. This new PPAR modulator is giving promising results both in vitro and in vivo, without toxicity and is currently evaluated in a phase 2 clinical trial. The aim of this review is to present and discuss the evidence suggesting that PPARγ targeting is of therapeutic interest in the treatment of UC.