Therapeutic Target In Inflammatory Bowel Disease Research Articles

MiRNAs as new molecular insights into inflammatory bowel disease: Crucial regulators in autoimmunity and inflammation.

Inflammatory bowel disease (IBD) is characterized by chronic relapsing inflammatory disorders of the gastrointestinal tract, and includes two major phenotypes: ulcerative colitis and Crohn's disease. The pathogenesis of IBD is not fully understood as of yet. It is believed that IBD results from complicated interactions between environmental factors, genetic predisposition, and immune disorders. miRNAs are a class of small non-coding RNAs that can regulate gene expression by targeting the 3'-untranslated region of specific mRNAs for degradation or translational inhibition. miRNAs are considered to play crucial regulatory roles in many biologic processes, such as immune cellular differentiation, proliferation, and apoptosis, and maintenance of immune homeostasis. Recently, aberrant expression of miRNAs was revealed to play an important role in autoimmune diseases, including IBD. In this review, we discuss the current understanding of how miRNAs regulate autoimmunity and inflammation by affecting the differentiation, maturation, and function of various immune cells. In particular, we focus on describing specific miRNA expression profiles in tissues and peripheral blood that may be associated with the pathogenesis of IBD. In addition, we summarize the opportunities for utilizing miRNAs as new biomarkers and as potential therapeutic targets in IBD.

The Gut Microbiota as a Therapeutic Target in IBD and Metabolic Disease: A Role for the Bile Acid Receptors FXR and TGR5.

The gut microbiota plays a crucial role in regulating many physiological systems of the host, including the metabolic and immune system. Disturbances in microbiota composition are increasingly correlated with disease; however, the underlying mechanisms are not well understood. Recent evidence suggests that changes in microbiota composition directly affect the metabolism of bile salts. Next to their role in digestion of dietary fats, bile salts function as signaling molecules for bile salt receptors such as Farnesoid X receptor (FXR) and G protein-coupled bile acid receptor (TGR5). Complementary to their role in metabolism, FXR and TGR5 are shown to play a role in intestinal homeostasis and immune regulation. This review presents an overview of evidence showing that changes in bile salt pool and composition due to changes in gut microbial composition contribute to the pathogenesis of inflammatory bowel disease and metabolic disease, possibly through altered activation of TGR5 and FXR. We further discuss how dietary interventions, such as pro- and synbiotics, may be used to treat metabolic disease and inflammatory bowel disease (IBD) through normalization of bile acid dysregulation directly or indirectly through normalization of the intestinal microbiota.

Butyrate and Mucosal Inflammation: New Scientific Evidence Supports Clinical Observation

Butyrate and Mucosal Inflammation: New Scientific Evidence Supports Clinical Observation

Mo1714 Analysis of the Protease MT1-MMP As Therapeutic Target in IBD

Background: We have recently demonstrate higher levels of the MT1-MMP by qPCR -in biopsiesand higher levels of its substrates thrombospondin-1 (TSP1) and nidogen-1 (NID1) -in serumfrom patients of inflammatory bowel disease (IBD), a chronic disorder involving inflammation and angiogenesis. Our objective was analysing the functional role of MT1MMP in the angiogenesis and damage produced in IBD. Methods: Gene expression of MT1MMP was detected by qPCR in biopsies, and TNFα, VEGFA, TSP1, NID1 levels were quantified by ELISA in serum from patients with active ulcerative colitis (UC) or Crohn's disease (CD). Clinical IBD activity was assessed respectively by the Mayo score for UC, and by the Harvey-Bradshaw index for CD. Endoscopic activity was determined with the Mayo subscore and the SES-CD index. MT1-MMP, TSP1 and NID1 expression and the angiogenic response were also analyzed by immunostaining (IF) in colonic sections from controls or patients affected by IBD. Besides, we used a mouse model of dextran sulphate sodium (DSS)induced colitis to analysed the angiogenic response by IF with the specific endothelial cell markers CD31, VE cadherin, and the expression of MT1-MMP, and its substrates TSP1 and NID1 by IF of histological colon sections from either control mice or mice treated with 1% DSS (moderate colitis) or 4% DSS (severe colitis), in wild type mice. The endothelial MT1MMP expression was also analysed in MT1-MMPLacZ/+ mice. Finally, the in vivo functional analysis was done in mice with endothelium-specific deletion of MT1-MMP generated by (MT1-MMPflox/floxxVECadhERT2-Cre) breeding analyzing: (i) colitis score; (ii) vascular pattern quantifying, perfusion, endothelial proliferation and colonic hypoxia (injection and stainings of isolectinB4, EdU, and Pimonidazole); and (iii) inflammatory infiltrate (IF with CD11b). Results: MT1-MMP expression was higher in biopsies of patients with active IBD, moreover, serum levels of TSP-1 and NID1 were significantly increased in UC and CD patients with low activity. In the mouse colitis model, serum levels of TNFα, VEGF-A, TSP1 y NID1 and MT1-MMP expression in intestinal tissues, were increased along the progression of the mouse disease, as well as the angiogenesis in the intestinal mucosa. Our preliminary results indicate that the absence of MT1-MMP in EC protects from IBD, through a vascular normalization (reestablishment of structure and function of blood vessels), with the consequent decrease of colonic hypoxia and inflammation. Conclusions: These data support the potential use of TSP1 and NID1 as biomarkers in the diagnostic of pre-symptomatic or low activity IBD, aiming the endothelial MT1-MMP as a new therapeutic target for normalization of vasculature and improve the symptoms in IBD.

Spontaneous and transgenic rodent models of inflammatory bowel disease.

Inflammatory Bowel Disease (IBD) is a multifactorial disorder with many different putative influences mediating disease onset, severity, progression and diminution. Spontaneous natural IBD is classically expressed as Crohn's Disease (CD) and Ulcerative Colitis (UC) commonly found in primates; lymphoplasmocytic enteritis, eosinophilic gastritis and colitis, and ulcerative colitis with neuronal hyperplasia in dogs; and colitis in horses. Spontaneous inflammatory bowel disease has been noted in a number of rodent models which differ in genetic strain background, induced mutation, microbiota influences and immunopathogenic pathways. Histological lesions in Crohn's Disease feature noncaseating granulomatous inflammation while UC lesions typically exhibit ulceration, lamina propria inflammatory infiltrates and lack of granuloma development. Intestinal inflammation caused by CD and UC is also associated with increased incidence of intestinal neoplasia. Transgenic murine models have determined underlying etiological influences and appropriate therapeutic targets in IBD. This literature review will discuss current opinion and findings in spontaneous IBD, highlight selected transgenic rodent models of IBD and discuss their respective pathogenic mechanisms. It is very important to provide accommodation of induced putative deficits in activities of daily living and to assess discomfort and pain levels in the face of significant morbidity and/or mortality in these models. Epigenetic, environmental (microbiome, metabolome) and nutritional factors are important in IBD pathogenesis, and evaluating ways in which they influence disease expression represent potential investigative approaches with the greatest potential for new discoveries.

Intestinal Permeability in Inflammatory Bowel Disease: Pathogenesis, Clinical Evaluation, and Therapy of Leaky Gut.

The pathogenesis of inflammatory bowel disease (IBD) is multifactorial with data suggesting the role of a disturbed interaction between the gut and the intestinal microbiota. A defective mucosal barrier may result in increased intestinal permeability which promotes the exposition to luminal content and triggers an immunological response that promotes intestinal inflammation. IBD patients display several defects in the many specialized components of mucosal barrier, from the mucus layer composition to the adhesion molecules that regulate paracellular permeability. These alterations may represent a primary dysfunction in Crohn's disease, but they may also perpetuate chronic mucosal inflammation in ulcerative colitis. In clinical practice, several studies have documented that changes in intestinal permeability can predict IBD course. Functional tests, such as the sugar absorption tests or the novel imaging technique using confocal laser endomicroscopy, allow an in vivo assessment of gut barrier integrity. Antitumor necrosis factor-α (TNF-α) therapy reduces mucosal inflammation and restores intestinal permeability in IBD patients. Butyrate, zinc, and some probiotics also ameliorate mucosal barrier dysfunction but their use is still limited and further studies are needed before considering permeability manipulation as a therapeutic target in IBD.

Heme Oxygenase-1 Ameliorates Dextran Sulfate Sodium-induced Acute Murine Colitis by Regulating Th17/Treg Cell Balance

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is a group of autoimmune diseases characterized by nonspecific inflammation in the gastrointestinal tract. Recent investigations suggest that activation of Th17 cells and/or deficiency of regulatory T cells (Treg) is involved in the pathogenesis of IBD. Heme oxygenase (HO)-1 is a protein with a wide range of anti-inflammatory and immune regulatory function, which exerts significantly protective roles in various T cell-mediated diseases. In this study, we aim to explore the immunological regulation of HO-1 in the dextran sulfate sodium-induced model of experimental murine colitis. BALB/c mice were administered 4% dextran sulfate sodium orally; some mice were intraperitoneally pretreated with HO-1 inducer hemin or HO-1 inhibitor stannum protoporphyrin IX. The results show that hemin enhances the colonic expression of HO-1 and significantly ameliorates the symptoms of colitis with improved histological changes, accompanied by a decreased proportion of Th17 cells and increased number of Tregs in mesenteric lymph node and spleen. Moreover, induction of HO-1 down-regulates retinoic acid-related orphan receptor γt expression and IL-17A levels, while promoting Treg-related forkhead box p3 (Foxp3) expression and IL-10 levels in colon. Further study in vitro revealed that up-regulated HO-1 switched the naive T cells to Tregs when cultured under a Th17-inducing environment, which involved in IL-6R blockade. Therefore, HO-1 may exhibit anti-inflammatory activity in the murine model of acute experimental colitis via regulating the balance between Th17 and Treg cells, thus providing a possible novel therapeutic target in IBD.

Gadolinium chloride improves the course of TNBS and DSS-induced colitis through protecting against colonic mucosal inflammation.

Inflammatory macrophages in colonic mucosa are the leading drivers of the pathology associated with inflammatory bowel disease (IBD). Here we examined whether gadolinium chloride (GdCl3), a macrophage selective inhibitor, would improve the course of 2,4,6-trinitro benzene sulfonic acid (TNBS) and dextran sodium sulfate (DSS)-induced colitis in mice and the potential mechanisms were investigated. By giving GdCl3 to colitis mice through intravenous or intrarectal route, we found that GdCl3 markedly ameliorated the colitis severity, including less weight loss, decreased disease activity index scores, and improved mucosal damage. To investigate the potential mechanisms, flow-cytometric analysis was performed to detect the proportion of mucosal macrophages in colon. The results showed that GdCl3 had no macrophage depletion effect in colonic mucosa, but significantly suppressed TNBS and DSS-induced TNFα, IL-1β and IL-6 secretions. Also, Western blotting analysis indicated that NF-κB p65 expression was significantly attenuated in the mucosa in colitis mice with GdCl3 treatment. Then, the anti-inflammatory activity of GdCl3 was confirmed in LPS-stimulated RAW 264.7 cells that GdCl3 might down-regulate the production of proinflammatory cytokines by macrophages through inhibition of the NF-κB signaling pathway. Therefore, intervention with mucosal inflammatory macrophages may be a promising therapeutic target in IBD.

Carboxypeptidase E modulates intestinal immune homeostasis and protects against experimental colitis in mice.

Enteroendocrine cells (EEC) produce neuropeptides, which are crucially involved in the maintenance of the intestinal barrier. Hence, EEC dysfunction is suggested to be involved in the complex pathophysiology of inflammatory bowel disease (IBD), which is characterized by decreased intestinal barrier function. However, the underlying mechanisms for EEC dysfunction are not clear and suitable models for a better understanding are lacking. Here, we demonstrate that Carboxypeptidase E (CPE) is specifically expressed in EEC of the murine colon and ileum and that its deficiency is associated with reduced intestinal levels of Neuropeptide Y (NPY) and Peptide YY (PYY), which are both produced by EEC. Moreover, cpe−/− mice exhibit an aggravated course of DSS-induced chronic colitis compared to wildtype littermates. In addition, we observed elevated mucosal IL-6 and KC transcript levels already at baseline conditions in cpe−/− mice. Moreover, supernatants obtained from isolated intestinal crypts of cpe−/− mice lead to increased IL-6 and KC expression in MODE-K cells in the presence of LPS. This effect was reversible by co-administration of recombinant NPY, suggesting a CPE mediated immunosuppressive effect in the intestines by influencing the processing of specific neuropeptides. In this context, the chemotaxis of bone marrow derived macrophages towards respective supernatants was enhanced. In conclusion, our data point to an anti-inflammatory role of CPE in the intestine by influencing local cytokine levels and thus regulating the migration of myeloid immune cells into the mucosa. These findings highlight the importance of EEC for intestinal homeostasis and propose EEC as potential therapeutic targets in IBD.

Adhesion Molecules as a Therapeutic Target in IBD

Recruitment of circulating leukocytes to areas of inflammation is a key process in the pathophysiology of inflammatory bowel diseases, including ulcerative colitis (UC). This is a finely regulated multistep process in which specialised adhesion and signalling molecules mediate a series of sequential steps. Following activation, integrins expressed on the surface of leukocytes become the key mediators of firm adhesion and emigration through interaction with immunoglobulin superfamily molecules expressed on the vascular endothelium. The anti α4 antibody natalizumab has shown efficacy in inducing and maintaining response and remission in patients with moderate and severe Crohn’s disease. However, a major safety setback involving the onset of progressive multifocal leukoencephalopathy (PML) in 1/1000 treated cases led to limitations on its clinical use and application in UC. The more selective anti α4β7 antibody vedolizumab has proven efficacious for inducing clinical and endoscopic remission in UC. Selective expression of the α4β7 receptor MAdCAM-1, which occurs predominantly in the intestine, may avoid the risk of those central nervous system infectious complications associated with the nonselective blockade of all α4 integrins. Moreover, treatment with anti-MAdCAM-1 or anti-α7 antibody (etrolizumab) showed promising results for inducing remission in UC. In conclusion, the development of safe and effective drugs that target these molecular components of the inflammatory response may yield novel, improved therapies for inflammatory bowel disease (IBD) that address as yet unmet needs.

Hydroxylases as therapeutic targets in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a common and debilitating clinical disorder comprising ulcerative colitis and Crohn's disease. IBD occurs when inappropriate immunological activity in the intestinal mucosa results in epithelial barrier dysfunction leading to exposure of the mucosal immune system to luminal antigenic material. This in turn results in the cycles of inflammation and further barrier dysfunction which underlie disease progression. Although significant therapeutic advances have been made over the last decade, current immunosuppressive and anti-inflammatory treatments for IBD have significant limitations due to lack of treatment response in some patients and adverse effects, including increased risk of infection and malignancy. Recent studies using experimental models of IBD have identified that intracellular hydroxylases, a group of enzymes responsible for oxygen sensing and activation of adaptive transcriptional responses to hypoxia may represent a new class of therapeutic targets in IBD. Hydroxylase inhibitors are effective in ameliorating symptoms of colitis at least in part through the promotion of intestinal epithelial barrier function. The mechanism of this protection is due to activation of hypoxia-sensitive transcription factors, including the hypoxia-inducible factor (HIF) and nuclear factor kappa-B (NF-κB), which activate specific epithelial barrier-protective transcriptional programs. In this review, the mechanism(s) of action and the therapeutic potential of small molecule hydroxylase inhibitors for the treatment of IBD will be discussed.

High Intestinal and Systemic Levels of Interleukin-23/T-Helper 17 Pathway in Chinese Patients with Inflammatory Bowel Disease

Interleukin-23/T-helper 17 (IL-23/Th17) pathway plays a key role in the pathogenesis of inflammatory bowel disease (IBD), but little is known about its expression in Chinese population. In this study, we investigated the mRNA and protein levels of IL-12p40, tumor necrosis factor-like cytokine 1A (TL1A), Janus kinase 2 (JAK2), and IL-23R both locally and systemically in Chinese IBD patients. Our results indicated that the mRNA levels of IL-12p40 and TL1A were increased in ulcerative colitis (UC) patients. Furthermore, serum IL-12p40 and TL1A levels were higher in active UC patients, especially in patients with disease course less than 1.25 years or initial onset. No correlation was found between the genotype and serum levels of IL-12p40 or TL1A in UC patients. Additionally, the mRNA and protein expression of JAK2 and IL-23R were increased in UC and Crohn's disease (CD) patients. Taken together, our results provided evidence that IL-23/Th17 pathway genes may represent important biomarkers of active stage of IBD and serve as novel therapeutic targets for IBD in Chinese population.

HLA-DRhi and CCR9 Define a Pro-Inflammatory Monocyte Subset in IBD

OBJECTIVES:It has been demonstrated that circulating monocytes relocate to the intestinal mucosa during intestinal inflammation, but the phenotype and inflammatory mechanisms of these monocytes remain poorly understood. Here, we have investigated blood monocytes expressing high levels of HLA-DR and CCR9 in patients with inflammatory bowel disease (IBD).METHODS:Fifty-one patients with mild to severe ulcerative colitis (UC; n=31; UC-DAI 3–12) or Crohn's disease (CD; n=20; Harvey–Bradshaw indices (HBI) 2–16) were included together with 14 controls, during IBD therapy for four consecutive weeks. The frequency of CD14+HLA-DRhi monocytes was monitored weekly in peripheral blood, using flow cytometry. The surface phenotype and cytokine profile of these monocytes were established using flow cytometry and real-time PCR. Clinical parameters were assessed weekly in all patients.RESULTS:The frequency of circulating CD14+HLA-DRhi monocytes was significantly higher in IBD patients with moderate to severe disease compared with healthy controls (P<0.001). During treatment with corticosteroids and granulocyte/monocyte apheresis, the proportion of circulating CD14+HLA-DRhi monocytes was significantly reduced. CD14+HLA-DRhi monocytes produced high levels of inflammatory mediators, such as tumor necrosis factor (TNF)-α, and expressed the gut-homing receptor CCR9. Furthermore, we found that the CCR9 ligand, CCL25/TECK, was expressed at high levels in the colonic mucosa in IBD patients with active disease.CONCLUSIONS:CD14+HLA-DRhi blood monocytes were increased in patients with active IBD. These monocytes exhibit a pro-inflammatory, gut-homing phenotype with regard to their TNF-α production and expression of CCR9. Our results suggest that these monocytes are important in mediating intestinal inflammation, and provide potential therapeutic targets in IBD.

Transcriptional Regulation of IL-10 Expression by Peroxisome Proliferator-Activated Receptor (Pparγ) in Human Intestinal Epithelial Cells

IL-10 is an important immunomodulatory cytokine in the regulation of intestinal inflammation in inflammatory bowel disease (IBD). PPARγ is a nuclear receptor known to modulate transcriptional activities of many cytokines and is highly expressed in intestinal epithelial cells (IECs). Human IECs have been shown to express IL-10, but how its expression is regulated remains obscure especially in the setting of inflammation. We have demonstrated that intestinal 15d-PGJ2 (an endogenous PPARγ ligand) is predominantly induced by infiltrated macrophages (Mφs) through toll-like receptor 4 (TLR4)-mediated Cox-2 induction during colitis. In this study, we addressed whether PPARγ activation regulates expression of IL-10 in IECs. Human IEC cell line SW480-APC expressing TLR4 (top) and mouse peritoneal Mφs (bottom) were co-cultured in transwells. 15d-PGJ2 production and IL-10 mRNA expression were measured by enzyme linked assay and real-time PCR in the presence or absence of lipopolysaccharide (LPS). In order to examine whether the IL-10 promoter has PPARγ responsive elements, a 2,000 bp of IL-10 promoter was cloned from SW480-APC genomic DNA into the luciferase reporter vector. Expression and activity of PPARγ were blocked by siRNA and a specific inhibitor SR202, respectively. The IL-10 promoter activity was analyzed by luciferase reporter assay. PPARγ activity was confirmed using a reporter vector PPRE X3-TK-luc. Co-culturing SW480-APC with Mφs increased IL-10 expression in IECs within 24 hours, which was significantly enhanced by LPS stimulation in later time point (72 hours). LPS stimulation of SW480-APC resulted in PPARγ activation peaked at 48 hours. During SW480-APC/Mφ co-culture, LPS stimulation induced 15d-PGJ2 production, which is abolished when TLR4-deficient Mφs were used. Knocking down the expression of PPARγ suppressed IL-10 promoter activity and mRNA expression in SW480-APC in baseline as well as after LPS stimulation. These results suggest that PPARγ positively regulates IL-10 expression in IECs at the transcriptional level. During inflammation, mucosal Mφs induce PPARγ ligand (15d-PGJ2) in a TLR4-dependent manner that contributes to PPARγ activation in IECs and thus IL-10 expression. This may be an intrinsic immunoregulatory program that is mediated through host-bacterial interactions, which dampens on-going inflammation during intestinal inflammation and thus can be a novel therapeutic target for IBD.

Dipeptidyl peptidase-4 expression is reduced in Crohn's disease

BackgroundDipeptidyl peptidase 4 (DP4) is a serine protease that preferentially cleaves N‐terminal dipeptides from polypeptides containing proline or alanine as the penultimate amino acid. DP4 inactivates glucagon like peptide-2 (GLP-2), a trophic peptide with cytoprotective and reparative properties in the injured gut; therefore DP4 potentially inhibits repair processes. DP4 also modulates the activity of GLP-1 and polypeptide YY (PYY) which regulate appetite and motility. No data are yet available on the tissue and plasma expression of DP4 in inflammatory bowel disease (IBD). MethodsTissue and plasma were studied from active CD and healthy controls for DP4 quantification. Experiments were also carried out in a reductionist Caco-2 cell line model of intestinal inflammation with TNFα incubation. DP4 expression was studied by tissue Western blotting and plasma enzymelinked immunosorbent assay (ELISA), in addition to quantitative polymerase chain reaction (qPCR). ResultsThere was a ~2.7-fold decrease in DP4 protein in CD tissue (p=0.05). Plasma DP4 in CD was also significantly lower than the control group. A negative correlation between plasma DP4 levels and inflammatory activity as measured by C-reactive protein was observed. In Caco-2 cells an ~18-fold increase (p<0.0001) in DP4 protein expression was seen after incubation with TNFα at a concentration of 25ng/μl for 48hours paralleled by a 2-fold increase in DP4 mRNA. DiscussionDP4 is reduced in tissue and plasma in active Crohn's disease. This is unlikely to represent simple downregulation induced by inflammation since the key proinflammatory cytokine strongly upregulated DP4 expression in Caco-2 cells. Clearly a more complex situation exists in vivo. We propose that reduced DP4 activity limits the cleavage of regulatory peptides, for example potentiating the trophic signal from GLP-2. Pharmacological DP4 inhibition may present an additional therapeutic target in IBD.

Dipeptidyl Peptidase IV Expression in a Cellular and Human Model of Intestinal Inflammation

Introduction Dipeptidyl peptidase IV (DP IV) is a serine protease. It modulates the physiological activity of satiety inducing hormones such as glucagon like peptide 1 (GLP-1) and polypeptide YY (PYY). It also inactivates GLP-2, an enteroendocrine hormone with cytoprotective and reparative properties. By cleaving chemokines essential for the Th-2 inflammatory pathway, DP IV enhances the Th-1 pathway. Reduced serum DP IV activity has been observed in patients with inflammatory bowel disease (IBD) including Crohn9s disease (CD). Plasma levels and tissue expression have never been described together. The latter is of particular clinical significance since this is the local site of action of trophic GLP-2 and GLP-1 mediated vagal afferent stimulation. Methods Experiments were also carried out on a Caco-2 cell line model of intestinal inflammation with TNFα incubation in a graded concentration/time course. DP IV expression was studied at the mRNA level through quantitative PCR (qPCR) and protein level by tissue western blotting and plasma ELISA. DP IV expression was also studied in active small (n=18) and large bowel CD (n=5). A subgroup of patients were restudied when inactive (n=6) and all results were compared to healthy controls (n=17). Results In Caco-2 cells an ∼ 18-fold increase (p Conclusion Results in the reductionist cellular model of intestinal inflammation support an increase in DP IV in an inflammatory milieu. However, in the complex, chronic human disease DP IV expression is decreased, as observed in other inflammatory states such human inflammatory arthritis and systemic lupus erythematosus. It is possible that a decrease in DP IV would preserve more biologically active GLP-2, enhancing trophic activity and promoting repair. DP IV may present a potential therapeutic target in IBD.

Dipeptidyl peptidase IV expression in a cellular and human model of intestinal inflammation

IntroductionDipeptidyl peptidase IV (DP IV) is a serine protease. It modulates the physiological activity of satiety inducing hormones such as glucagon like peptide 1 (GLP-1) and polypeptide YY (PYY). It...

Nanoparticle-based therapeutic delivery of prohibitin to the colonic epithelial cells ameliorates acute murine colitis

Intestinal epithelial expression of antioxidants and nuclear factor kappa B (NF-κB) contribute to mucosal barrier integrity and epithelial homeostasis, two key events in the pathogenesis of inflammatory bowel disease (IBD). Genetic restoration of intestinal epithelial prohibitin 1 (PHB) levels during experimental colitis reduces the severity of disease through sustained epithelial antioxidant expression and reduced NF-κB activation. To determine the therapeutic potential of restoring epithelial PHB during experimental colitis in mice, we assessed two methods of PHB colonic mucosal delivery: adenovirus-directed administration by enema and poly(lactic acid) nanoparticle (NPs) delivery by gavage. As a proof-of-principle to demonstrate the therapeutic efficacy of PHB, we utilized adenovirus-directed administration by enema. Second, we used NPs-based colonic delivery of biologically active PHB to demonstrate therapeutic use for human IBD. Colitis was induced by oral administration of dextran sodium sulfate (DSS) in water for 6-7 days. Wildtype mice receiving normal tap water served as controls. Both methods of delivery resulted in increased levels of PHB in the surface epithelial cells of the colon and reduced severity of DSS-induced colitis in mice as measured by body weight loss, clinical score, myeloperoxidase activity, proinflammatory cytokine expression, histological score, and protein carbonyl content. This is the first study to show oral delivery of a biologically active protein by NPs encapsulated in hydrogel to the colon. Here we show that therapeutic delivery of PHB to the colon reduces the severity of DSS-induced colitis in mice. PHB may represent a novel therapeutic target in IBD.

Identification of microRNAs associated with ileal and colonic Crohnʼs disease†

Crohn's disease (CD) and ulcerative colitis (UC) are associated with expression differences in genes involved in immune function, wound healing, and tissue remodeling. MicroRNAs (miRNAs) are small, noncoding RNAs that act as potent negative regulators of gene expression and are differentially expressed in chronic inflammatory diseases, including UC. We examined the expression of miRNAs in tissues from different intestinal regions and in patients with active ileal and colonic CD. Colonoscopic pinch biopsies were obtained from the terminal ileum, cecum, transverse colon, sigmoid colon, and rectum of normal, healthy adults and from the ileum and sigmoid colon of patients with active ileal and colonic CD. miRNA expression was assessed using miRNA microarray and validated by mature miRNA quantitative reverse-transcription polymerase chain reaction (RT-PCR). Ten intestine region-specific miRNAs were identified. Three miRNAs were increased and one miRNA was decreased in the terminal ileum as compared to the colon. Six other miRNAs expressed varying levels of expression among the colon regions. Five miRNAs were found to be differentially expressed in tissues of patients with active colonic CD, with three increased and two decreased as compared to normal, healthy controls. Similarly, four miRNAs were found to be significantly increased in tissues of patients with active ileal CD. The expression differences between ileal CD, colonic CD, and previously identified UC-associated miRNAs support the likelihood that miRNAs influence differing inflammation-related gene expression in each inflammatory bowel disease (IBD) subtype and may form the basis for future diagnostic tests and therapeutic targets for IBD.

Endothelial Caveolin-1 Regulates Pathologic Angiogenesis in a Mouse Model of Colitis

Increased vascular density has been associated with progression of human inflammatory bowel diseases (IBDs) and animal models of colitis. Pathologic angiogenesis in chronically inflamed tissues is mediated by several factors that are regulated at specialized lipid rafts known as caveolae. Caveolin-1 (Cav-1), the major structural protein of caveolae in endothelial cells, is involved in the regulation of angiogenesis, so we investigated its role in experimental colitis. Colitis was induced by administration of dextran sodium sulfate to wild-type and Cav-1(-/-) mice, as well as Cav-1(-/-) mice that overexpress Cav-1 only in the endothelium. Colon tissues were analyzed by histologic analyses. Leukocyte recruitment was analyzed by intravital microscopy; angiogenesis was evaluated by immunohistochemistry and in vivo disk assays. Cav-1 protein levels increased after the induction of colitis in wild-type mice. In Cav-1(-/-) mice or mice given a Cav-1 inhibitory peptide, the colitis histopathology scores, vascular densities, and levels of inflammatory infiltrates decreased significantly compared with controls. Lower levels of leukocyte and platelet rolling and adhesion colitis also were observed in Cav-1(-/-) mice and mice given a Cav-1 inhibitory peptide, compared with controls. Cav-1(-/-) mice that received transplants of wild-type bone marrow had a lower colitis score than wild-type mice. Data from mice that overexpress Cav-1 only in the endothelium indicated that endothelial Cav-1 is the critical regulator of colitis. Genetic deletion or pharmacologic inhibition of endothelial Cav-1 also significantly decreased vascular densities and angiogenesis scores, compared with controls. Endothelial Cav-1 mediates angiogenesis in experimental colitis. Modulation of Cav-1 could provide a novel therapeutic target for IBD.