Target In Inflammatory Bowel Disease Research Articles

Adhesive Interactions between Mononuclear Phagocytes and Intestinal Epithelium Perturb Normal Epithelial Differentiation and Serve as a Therapeutic Target in Inflammatory Bowel Disease.

Disturbance of intestinal homeostasis is associated with the development of inflammatory bowel disease [IBD], and TGF-β signalling impairment in mononuclear phagocytes [MPs] causes murine colitis with goblet cell depletion. Here, we examined an organoid-MP co-culture system to study the role of MPs in intestinal epithelial differentiation and homeostasis. Intestinal organoids were co-cultured with lamina propria leukocytes and bone marrow-derived dendritic cells [BMDCs] from CD11c-cre Tgfbr2fl/fl mice. Organoid-MP adhesive interactions were evaluated by microscopy, RT-PCR, and flow cytometry. Murine colitis models (dextran sodium sulphate [DSS], CD11c-cre Tgfbr2fl/fl, T-cell-transfer) were used for histological and immunohistochemical analysis. Anti-E-cadherin antibody treatment or CD11c+-cell-specific CDH1 gene deletion were performed for E-cadherin neutralization or knockout. Colonic biopsies from patients with ulcerative colitis were analysed by flow cytometry. Intestinal organoids co-cultured with CD11c+ lamina propria leukocytes or BMDCs from CD11c-cre Tgfbr2fl/fl mice showed morphological changes and goblet cell depletion with Notch signal activation, analogous to CD11c-cre Tgfbr2fl/fl colitis. E-cadherin was upregulated in CD11c+ MPs, especially CX3CR1+CCR2+ monocytes, of CD11c-cre Tgfbr2fl/fl mice. E-cadherin-mediated BMDC adhesion promoted Notch activation and cystic changes in organoids. Anti-E-cadherin antibody treatment attenuated colitis in CD11c-cre Tgfbr2fl/fl and T-cell-transferred mice. In addition, E-cadherin deletion in CD11c+ cells attenuated colitis in both CD11c-cre Tgfbr2fl/fl and DSS-treated mice. In patients with ulcerative colitis, E-cadherin expressed by intestinal CD11c+ leukocytes was enhanced compared with that in healthy controls. E-cadherin-mediated MP-epithelium adhesion is associated with the development of colitis, and blocking these adhesions may have therapeutic potential for IBD.

Targeting Endothelial Ligands: ICAM-1/alicaforsen, MAdCAM-1.

Specific blockade of the endothelial ligands intercellular adhesion molecule-1 [ICAM-1] and mucosal addressin cell adhesion molecule [MAdCAM] involved in leukocyte recruitment to the site of inflammation as therapeutic targets in inflammatory bowel disease [IBD] has been recognized from their overexpression in the inflamed mucosa and successful intervention based on these ligands in preclinical animal models. Interventions to target ICAM-1 in human IBD are confined to the ICAM-1 anti-sense oligonucleotide alicaforsen. While results with parenteral formulations of alicaforsen in Crohn's disease have largely been negative, efficacy signals derived from studies with an enema formulation in ulcerative colitis and pouchitis are promising and have led to a Food and Drug Administration Fast-Track designation for the latter. A large phase III programme in pouchitis is underway. Phase II studies with the anti-MAdCAM-1 antibody [SHP647] delivered positive results in ulcerative colitis and anti-inflammatory signals in Crohn's disease. Furthermore, it was shown that SHP647 does not affect the number and composition of cells in cerebrospinal fluid, suggesting that the compound is not affecting immune surveillance in the central nervous system. In addition, both alicaforsen and SHP647 are promising compounds based on the clear safety profile observed so far.

Inflammatory caspase-related pyroptosis: mechanism, regulation and therapeutic potential for inflammatory bowel disease.

As an essential part of programmed cell death, pyroptosis is an inflammatory response that is elicited upon infection by intracellular pathogens. Metabolic diseases, atherosclerosis and vital organ damage occur if pyroptosis is over-activated. Macrophages are the main cells that induce pyroptosis with the help of intracellular pattern-recognition receptors stimulated by danger signals and pathogenic microorganisms in the cytosol of host cells. Activated inflammatory caspases induce pyroptosis and produce pro-inflammatory cytokines, such as interleukin-1β and interleukin-18. Inflammatory programmed cell death is classified as canonical or non-canonical based on inflammatory caspases, which includes caspase-1 (in human and mouse) and caspase-11 (in mouse) or caspase-4 and -5 (in humans). Activated inflammatory caspases cleave the pore-forming effector protein, gasdermin-D, inducing osmotic pressure deregulation of internal fluids and subsequently rupturing the cell membranes. Inflammatory caspases could be attractive therapeutic targets for inflammatory bowel disease (IBD) in which pyroptosis may play an important role. This article reviews the current understanding of the mechanism of pyroptosis, focusing on the regulation of inflammatory caspases and therapeutic strategies for IBD.

Chemokines and Chemokine Receptors as Therapeutic Targets in Inflammatory Bowel Disease; Pitfalls and Promise.

The principal targets for anti-chemokine therapy in inflammatory bowel disease (IBD) have been the receptors CCR9 and CXCR3 and their respective ligands CCL25 and CXCL10. More recently CCR6 and its ligand CCL20 have also received attention, the expression of the latter in enterocytes being manipulated through Smad7 signalling. These pathways, selected based on their fundamental role in regulating mucosal immunity, have led to the development of several therapeutic candidates that have been tested in early phase clinical trials with variable clinical efficacy. In this article, we appraise the status of chemokine-directed therapy in IBD, review recent developments, and nominate future areas for therapeutic focus.

P112 LXR-ABCA1 pathway: a therapeutic target in inflammatory bowel disease?

P112 LXR-ABCA1 pathway: a therapeutic target in inflammatory bowel disease?

OP014 Analysis of 1792 gut metagenomes reveals microbial treatment targets for inflammatory bowel disease and irritable bowel syndrome

OP014 Analysis of 1792 gut metagenomes reveals microbial treatment targets for inflammatory bowel disease and irritable bowel syndrome

Keep Calm and Treat to Target in Inflammatory Bowel Disease

The goal of this symposium was to highlight the importance of early diagnosis, assessing prognostic factors, and treating to target in inflammatory bowel disease (IBD). In the introduction, Prof Colombel outlined the treat to target (T2T) and tight control (TC) approach, which involves predefining treatment targets in consultation with patients, continuously monitoring disease activity, and modifying treatments until targets are achieved. Dr Pariente presented regarding the progressiveness of Crohn’s disease (CD) and described the Lémann index (LI), which assesses cumulative structural damage in CD.1 He outlined the ‘window of opportunity’ in early disease, within which disease progression could be stopped. Dr Pariente said the T2T approach presents the opportunity for a personalised method of treatment; if targets are not achieved, treatment is intensified or switched. Prof Colombel presented the results of the CALM study,2 in which CD patients were randomised 1:1 to clinical management (CM) or TC, meaning treatment was escalated based on clinical symptoms in combination with biomarkers. The primary endpoint of mucosal healing and no deep ulceration was achieved by 45.9% of patients in the TC arm versus 30.3% in the CM arm (p=0.010). Lastly, Prof D’Haens presented a cost-effectiveness analysis using data from CALM. The calculated total direct medical costs for the TC arm were £13,296 versus £12,627 for the CM arm (a direct medical cost difference of £669).3 The quality-adjusted life years (QALY) were 0.684 for the TC arm versus 0.652 for the CM arm (giving a QALY difference of 0.032). The incremental cost-effectiveness ratio showed a cost of £20,913 per QALY gained, which falls within the threshold of The National Institute for Health and Care Excellence (NICE) guidance for cost-effectiveness.

A role for bacterial urease in gut dysbiosis and Crohn's disease.

Gut dysbiosis during inflammatory bowel disease involves alterations in the gut microbiota associated with inflammation of the host gut. We used a combination of shotgun metagenomic sequencing and metabolomics to analyze fecal samples from pediatric patients with Crohn's disease and found an association between disease severity, gut dysbiosis, and bacterial production of free amino acids. Nitrogen flux studies using 15N in mice showed that activity of bacterial urease, an enzyme that releases ammonia by hydrolysis of host urea, led to the transfer of murine host-derived nitrogen to the gut microbiota where it was used for amino acid synthesis. Inoculation of a conventional murine host (pretreated with antibiotics and polyethylene glycol) with commensal Escherichia coli engineered to express urease led to dysbiosis of the gut microbiota, resulting in a predominance of Proteobacteria species. This was associated with a worsening of immune-mediated colitis in these animals. A potential role for altered urease expression and nitrogen flux in the development of gut dysbiosis suggests that bacterial urease may be a potential therapeutic target for inflammatory bowel diseases.

Thiadiazolidinone-8 Ameliorates Inflammation Associated with Experimental Colitis in Mice

Thiadiazolidinone-8 (TDZD-8) is an effective thiadiazolidinone derivate that is able to suppress the expression of inflammatory cytokines; it also presents tissue protective actions by glycogen synthase kinase (GSK)-3β inhibition, promoting thus an anti-inflammatory effect. Since inflammatory bowel disease is a chronic disease with reduced quality of life, where currently available therapies are only able to induce or maintain the patient in remission, it is crucial to investigate new pharmacological approaches. The main objective of this study was to evaluate the effect of TDZD-8 in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis. Male CD-1 mice with TNBS-induced colitis were treated with a daily dose of TDZD-8 5 mg/kg/day IP during 4 days. The anti-inflammatory properties of TDZD-8 in the TNBS-induced colitis were confirmed by suppression of pro-inflammatory mediators, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β and myeloperoxidase, as well as by the significant increase of the anti-inflammatory cytokine, IL-10. These treated mice also presented a reduction in fecal hemoglobin and alkaline phosphatase, suggesting a beneficial effect of TDZD-8. Furthermore, renal and hepatic biomarkers remained stabilized after treatment. In conclusion, TDZD-8 reduces the inflammatory response associated with TNBS-induced colitis in mice, and modulation of GSK-3β seems to be an interesting pharmacological target in colitis.

Oroxylin A inhibits colitis by inactivating NLRP3 inflammasome.

NLRP3 inflammasome is a novel therapeutic target for inflammatory bowel disease (IBD). The aim of this study was to investigate the anti-inflammatory effect of a bioactive flavonoid—oroxylin A on the treatment of dextran sulfate sodium (DSS)-induced murine colitis via targeting NLRP3 inflammasome. In this study, we found that oroxylin A attenuated experimental colitis in mice, including loss of body weights, shortening of the colon lengths and infiltration of inflammatory cells. The production of IL-1β, IL-6 and TNF-α in colon was also markedly reduced by oroxylin A. Moreover, oroxylin A significantly decreased the expression of NLRP3 in intestinal mucosal tissue. In addition, NLRP3-/- mice were observably protected from DSS-induced acute colitis, and oroxylin A treatment had no effects on attenuating inflammation in NLRP3-/- mice. Further study found that the activation of NLRP3 inflammasome was dose-dependently inhibited by oroxylin A in both THP-Ms and BMDMs, followed by decrease in the cleavage of caspase-1 and secretion of IL-1β. This inhibitory effect of oroxylin A was due to restraint of the NLRP3 protein expression and the inflammasome formation in macrophages. Furthermore, the reduction of NLRP3 protein expression by oroxylin A was dependent on the inhibition of NF-κB p65 expression and nuclear translocation. Besides, oroxylin A directly suppressed the ASC speck formation and the inflammasome assembly which in turn restrained the activation of NLRP3 inflammasome. Our findings demonstrated that oroxylin A inhibited NLRP3 inflammasome activation and could potentially be used for the treatment of IBD.

Tissue metabolism and the inflammatory bowel diseases.

The intestinal mucosa provides a selective barrier between the anaerobic lumen and a highly metabolic lamina propria. A number of recent studies indicate that acute inflammation of the mucosa can result in tissue hypoxia and associated shifts in tissue metabolism. The activation of hypoxia-inducible factor (HIF) under these conditions has been demonstrated to function as an endogenous molecular cue to promote resolution of inflammation, particularly through the orchestration of barrier repair toward homeostasis. Given the central role of oxygen in tissue metabolism, ongoing studies have defined metabolic endpoints of HIF stabilization as important biomarkers of disease activity. Such findings make HIF and HIF-associated metabolic pathways particularly attractive therapeutic targets in inflammatory bowel disease (IBD). Here, we review the recent literature related to tissue metabolism in IBD.

Treat to Target in Inflammatory Bowel Disease: An Updated Review of Literature.

Therapeutic management of patients with inflammatory bowel diseases (IBDs) has, for years, been tailored towards monitoring patient clinical presentation as a way to gauge therapeutic management. With the advent of newer biological agents, treatment and management have begun to focus on more objective rather than subjective parameters. These objective parameters include endoscopic targets and focus on the impact of mucosal healing, radiologic and histologic targets, patient reported outcomes, and use of non-invasive biomarkers. However, a recent consensus statement has identified clinical/patient-reported outcome (PRO) remission and endoscopic remission (defined as a Mayo endoscopic subscore of 0-1) as the target for UC with histological remission being an adjunctive goal. For CD, clinical/PRO remission defined as resolution of abdominal pain and diarrhea/altered bowel habit and endoscopic remission, defined as resolution of ulceration at ileocolonoscopy, and resolution of findings of inflammation on cross-sectional imaging in patients who cannot be adequately assessed with ileocolonoscopy were the primary targets. Biomarker remission (normal C-reactive protein (CRP) and calprotectin) was considered as an adjunctive target. This approach requires continuous monitoring and therapeutic adjustments with an aim to achieve the target. This article attempts to review the most updated literature regarding the treat to target approach and thus provides current recommendations and supported evidence.

Genome-wide association study implicates immune activation of multiple integrin genes in inflammatory bowel disease.

Genetic association studies have identified 215 risk loci for inflammatory bowel disease 1–8, which have revealed fundamental aspects of its molecular biology. We performed a genome-wide association study of 25,305 individuals, and meta-analyzed with published summary statistics, yielding a total sample size of 59,957 subjects. We identified 25 new loci, three of which contain integrin genes that encode proteins in pathways identified as important therapeutic targets in inflammatory bowel disease. The associated variants are correlated with expression changes in response to immune stimulus at two of these genes (ITGA4, ITGB8) and at previously implicated loci (ITGAL, ICAM1). In all four cases, the expression increasing allele also increases disease risk. We also identified likely causal missense variants in the primary immune deficiency gene PLCG2 and a negative regulator of inflammation, SLAMF8. Our results demonstrate that new common variant associations continue to identify genes relevant to therapeutic target identification and prioritization.

Intracellular allosteric antagonism of the CCR9 receptor.

Chemokines and their G-protein-coupled receptors play a diverse role in immune defence by controlling the migration, activation and survival of immune cells. They are also involved in viral entry, tumour growth and metastasis and hence are important drug targets in a wide range of diseases. Despite very significant efforts by the pharmaceutical industry to develop drugs, with over 50 small-molecule drugs directed at the family entering clinical development, only two compounds have reached the market: maraviroc (CCR5) for HIV infection and plerixafor (CXCR4) for stem-cell mobilization. The high failure rate may in part be due to limited understanding of the mechanism of action of chemokine antagonists and an inability to optimize compounds in the absence of structural information. CC chemokine receptor type 9 (CCR9) activation by CCL25 plays a key role in leukocyte recruitment to the gut and represents a therapeutic target in inflammatory bowel disease. The selective CCR9 antagonist vercirnon progressed to phase 3 clinical trials in Crohn's disease but efficacy was limited, with the need for very high doses to block receptor activation. Here we report the crystal structure of the CCR9 receptor in complex with vercirnon at 2.8 Å resolution. Remarkably, vercirnon binds to the intracellular side of the receptor, exerting allosteric antagonism and preventing G-protein coupling. This binding site explains the need for relatively lipophilic ligands and describes another example of an allosteric site on G-protein-coupled receptors that can be targeted for drug design, not only at CCR9, but potentially extending to other chemokine receptors.

Pharmacology: Inside-out receptor inhibition.

Structures of two chemokine receptor proteins in complex with small molecules reveal a previously unknown binding pocket that could be a drug target for treating a range of diseases involving this receptor family. See Letters p.458 & p.462 Chemokine receptors are a family of G-protein-coupled receptors that regulate the migration of immune cells; their function has been implicated in a range of diseases. Two groups reporting in this issue of Nature describe crystal structures of two different chemokine receptors bound to small-molecule inhibitors. Tracy Handel and colleagues describe the structure of CCR2—a promising drug target for autoimmune, inflammatory and metabolic diseases as well as cancer—bound to orthosteric (BMS-681) and allosteric (CCR2-RA-[R]) antagonists. Fiona Marshall and colleagues describe the structure of CCR9—involved in immune cell recruitment to the gut and a promising drug target in inflammatory bowel disease—in complex with the selective CCR9 antagonist vercirnon. Both CCR2 and CCR9 structures reveal an allosteric pocket on the cytoplasmic face of the receptor. This allosteric pocket appears to be highly druggable, and homologous pockets may be present on other chemokine receptors.

Therapeutic Targets in Inflammatory Bowel Disease: Current and Future

The etiology of inflammatory bowel disease (IBD) is not fully understood but is likely influenced by numerous factors such as genetic predisposition, environmental factors, like the microbiota, and social behaviors, including smoking and diet. In addition to anti-tumor necrosis factor therapy, we now have integrin inhibitors that target lymphocyte trafficking to the gastrointestinal tract (vedolizumab and natalizumab); however, unmet medical needs remain. Although several immunologic pathways have been implicated in the pathogenesis of IBD, targeting these with drug therapy has produced mixed results. Recent drug failures, particularly anti-interleukin-17 (anti-IL17) in Crohn’s disease and anti-IL13 in ulcerative colitis, highlight our fundamental lack of understanding of the impact of pathogenic heterogeneity in the treatment of IBD. In addition to a “failure of mechanism,” other reasons for drug failure may include issues with the drug itself—for example, insufficient activity, or lack of targeting, inadequate trial design or dosing, or potentially our inability to characterize patients who may be more (or less) responsive to a specific therapy. This review summarizes some of the successes and failures and evaluates therapies currently under investigation for IBD.

Treatment Targets in Inflammatory Bowel Disease: Current Status in Daily Practice.

Recently, treatment goals in inflammatory bowel disease (IBD) in clinical trials have shifted from mainly symptom-based to more mucosa-driven. Real world data on treatment priorities are lacking. We aimed to investigate the current practice and most commonly used definitions of IBD treatment targets among Dutch gastroenterologists. Dutch gastroenterologists were asked to participate in a computer-based nation-wide survey. We asked questions on demographics, opinion and current practice regarding IBD treatment targets. Twenty-four percent (134/556) of the respondents completed the survey. For both Crohn's disease (CD) (47.3%, 61/129) and ulcerative colitis (UC)(45%, 58/129) the main treatment goal was to achieve and maintain deep remission, defined as clinical, biochemical and endoscopic remission. Seventy-six percent of the participants use mucosal healing (MH) as a potential treatment target for IBD, whereas 22.6% use histological remission. There is no single definition for MH in IBD. The majority use Mayo score ≤ 1 in UC (52%) and 'macroscopic normal mucosa' in CD (66%). More stringent and mucosa-driven treatment targets as 'deep remission' and 'mucosal healing' have found traction in clinical practice. The most commonly used definition for MH in routine practice is endoscopic MAYO score </= 1 in UC and 'macroscopic normal mucosa' in CD.

Targeting the Integrin α4β7 with Probiotics and Nutraceuticals: A Working Hypothesis

α4β7 integrin is critical in lymphocytes homing to the gut, a clinical relevant marker and a therapeutic target in inflammatory bowel disease (IBD). Deregulated β7-mediated T lymphocytes homing was observed also in the extra-intestinal manifestations of IBD and in subjects with the irritable bowel syndrome (IBS). Nutritional interventions and/ or functional foods (containing prebiotics, probiotics and/or nutraceuticals), rather than drug treatments, should be recommended in IBS. Despite dysbiosis is a common feature of both IBD and IBS, the modulation of gut microbiota and gut functional symptoms by dietary regimes, prebiotics, probiotics, symbiotics, as well as by herbal medicinal products and foods containing bioactive phytochemicals, requires future well-designed clinical trials to establish their safety and efficacy. Results from in vitro and animal models suggest a role of α4β7 integrin also in high-fat diet (HFD)-induced insulin resistance (IR) and atherosclerosis, as well as the potential modulation of gut homing by dietary phytochemicals and probiotics. Despite there was no significant difference in cholesterol levels between HFD fed ApoE-/- and β7-/-ApoE-/- mice, the latter had a reduced size of atherosclerotic lesions. Overall human and experimental data suggest that α4β7 integrin could be a target of functional foods and a useful marker in human studies, being sensitive to the complex interaction between genetic factors, microbiota and dietary habit.

Potential role for ET-2 acting through ETA receptors in experimental colitis in mice.

This study attempted to clarify the roles of endothelins and mechanisms associated with ETA/ETB receptors in mouse models of colitis. Colitis was induced by intracolonic administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS, 1.5mg/animal) or dextran sulfate sodium (DSS, 3%). After colitis establishment, mice received Atrasentan (ETA receptor antagonist, 10mg/kg), A-192621 (ETB receptor antagonist, 20mg/kg) or Dexamethasone (1mg/kg) and several inflammatory parameters were assessed, as well as mRNA levels for ET-1, ET-2 and ET receptors. Atrasentan treatment ameliorates TNBS- and DSS-induced colitis. In the TNBS model was observed reduction in macroscopic and microscopic score, colon weight, neutrophil influx, IL-1β, MIP-2 and keratinocyte chemoattractant (KC) levels, inhibition of adhesion molecules expression and restoration of IL-10 levels. However, A192621 treatment did not modify any parameter. ET-1 and ET-2 mRNA was decreased 24h, but ET-2 mRNA was markedly increased at 48h after TNBS. ET-2 was able to potentiate LPS-induced KC production in vitro. ETA and ETB receptors mRNA were increased at 24, 48 and 72h after colitis induction. Atrasentan treatment was effective in reducing the severity of colitis in DSS- and TNBS-treated mice, suggesting that ETA receptors might be a potential target for inflammatory bowel diseases.

NOD2 up-regulates TLR2-mediated IL-23p19 expression via NF-κB subunit c-Rel in Paneth cell-like cells.

IL-23p19 plays important roles in intestinal antimicrobial immunity, while its over-expression can lead to intestinal inflammation. However, the bacterial compounds and the type of pattern recognition receptor involved in the inducible expression of IL-23p19 in Paneth cells remain unclear. Here we show that the mRNA expression of IL-23p19 was increased in Paneth cell (PC)-like cells stimulated by Toll-like receptor 2 (TLR2) ligands, peptidoglycan (PGN) and Pam3CSK4, and was further increased in the presence of nucleotide-binding oligomerization domain 2 (NOD2)-ligand muramyl dipeptide (MDP). However, its mRNA expression was decreased in NOD2-knockdown PC-like cells. Additionally, the c-Rel activation was increased in Pam3CSK4- or PGN-stimulated PC-like cells, but the PGN-induced c-Rel activation was decreased in NOD2-knockdown PC-like cells and had no significant difference compared with Pam3CSK4-induced c-Rel activation. Our results suggest that NOD2 up-regulates TLR2-mediated IL-23p19 expression via increasing c-Rel activation in PC-like cells. This finding might provide us with a novel therapeutic target for inflammatory bowel disease to inhibit IL-23p19 over-expression via the NOD2-c-Rel pathway.