Immune cell-derived signals governing epithelial phenotypes in homeostasis and inflammation.

The intestinal epithelium fulfills important physiological functions and forms a physical barrier to the intestinal lumen. Barrier function is regulated by several pathways, and its impairment contributes to the pathogenesis of inflammatory bowel disease (IBD), a chronic inflammatory condition affecting more than seven million people worldwide. Current treatment options specifically target inflammatory mediators and have led to improvement of clinical outcomes; however, a significant proportion of patients experience treatment failure. Pro-repair effects of inflammatory mediators on the epithelium are emerging. In this review we summarize current knowledge on involved epithelial pathways, identify open questions, and put recent findings into clinical perspective, and pro-repair effects. A detailed understanding of epithelial pathways integrating mucosal stimuli in homeostasis and inflammation is crucial for the development of novel, more targeted therapies.

Kinase Signaling in Colitis-Associated Colon Cancer and Inflammatory Bowel Disease.

Colorectal cancer is a known complication of chronic inflammation of the colon ("colitis-associated colon cancer"). Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract. Patients with IBD are at increased risk of colon cancer compared to the general population. Kinase signaling pathways play critical roles in both the inflammation and regulating cellular processes such as proliferation and survival that contribute to cancer development. Here we review the interplay of kinase signaling pathways (mitogen-activated protein kinases, cyclin-dependent kinases, autophagy-activated kinases, JAK-STAT, and other kinases) and their effects on colitis-associated colon cancer. We also discuss the role of JAK-STAT signaling in the pathogenesis of IBD and the therapeutic landscape of JAK inhibitors for the treatment of IBD.

Investigating the Crime Scene-Molecular Signatures in Inflammatory Bowel Disease.

Inflammatory bowel diseases (IBD) are without cure and troublesome to manage because of the considerable diversity between patients and the lack of reliable biomarkers. Several studies have demonstrated that diet, gut microbiota, genetics and other patient factors are essential for disease occurrence and progression. Understanding the link between these factors is crucial for identifying molecular signatures that identify biomarkers to advance the management of IBD. Recent technological breakthroughs and data integration have fuelled the intensity of this research. This research demonstrates that the effect of diet depends on patient factors and gut microbial activity. It also identifies a range of potential biomarkers for IBD management, including mucosa-derived cytokines, gasdermins and neutrophil extracellular traps, all of which need further evaluation before clinical translation. This review provides an update on cutting-edge research in IBD that aims to improve disease management and patient quality of life.

Impact of fibre and red/processed meat intake on treatment outcomes among patients with chronic inflammatory diseases initiating biological therapy: A prospective cohort study.

Background: Biologic disease-modifying drugs have revolutionised the treatment of a number of chronic inflammatory diseases (CID). However, up to 60% of the patients do not have a sufficient response to treatment and there is a need for optimization of treatment strategies. Objective: To investigate if the treatment outcome of biological therapy is associated with the habitual dietary intake of fibre and red/processed meat in patients with a CID. Methods: In this multicentre prospective cohort study, we consecutively enrolled 233 adult patients with a diagnosis of Crohn's Disease, Ulcerative Colitis, Rheumatoid Arthritis (RA), Axial Spondyloarthritis, Psoriatic Arthritis and Psoriasis, for whom biologic therapy was planned, over a 3 year period. Patients with completed baseline food frequency questionnaires were stratified into a high fibre/low red and processed meat exposed group (HFLM) and an unexposed group (low fibre/high red and processed meat intake = LFHM). The primary outcome was the proportion of patients with a clinical response to biologic therapy after 14-16 weeks of treatment. Results: Of the 193 patients included in our primary analysis, 114 (59%) had a clinical response to biologic therapy. In the HFLM group (N = 64), 41 (64%) patients responded to treatment compared to 73 (56%) in the LFHM group (N = 129), but the difference was not statistically significant (OR: 1.48, 0.72-3.05). For RA patients however, HFLM diet was associated with a more likely clinical response (82% vs. 35%; OR: 9.84, 1.35-71.56). Conclusion: Habitual HFLM intake did not affect the clinical response to biological treatment across CIDs. HFLM diet in RA patients might be associated with better odds for responding to biological treatment, but this would need confirmation in a randomised trial. Trial registration: (clinicaltrials.gov), identifier [NCT03173144].

IBD metabonomics predicts phenotype, disease course, and treatment response.

Metabonomics in inflammatory bowel disease (IBD) characterizes the effector molecules of biological systems and thus aims to describe the molecular phenotype, generate insight into the pathology, and predict disease course and response to treatment. Nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), and integrated NMR and MS platforms coupled with multivariate analyses have been applied to create such metabolic profiles. Recent advances have identified quiescent ulcerative colitis as a distinct molecular phenotype and demonstrated metabonomics as a promising clinical tool for predicting relapse and response to treatment with biologics as well as fecal microbiome transplantation, thus facilitating much needed precision medicine. However, understanding this complex research field and how it translates into clinical settings is a challenge. This review aims to describe the current workflow, analytical strategies, and associated bioinformatics, and translate current IBD metabonomic knowledge into new potential clinically applicable treatment strategies, and outline future key translational perspectives.

Identification, isolation and analysis of human gut-associated lymphoid tissues.

Gut-associated lymphoid tissues (GALTs) comprise key intestinal immune inductive sites, including the Peyer's patches of the small intestine and different types of isolated lymphoid follicle (ILF) found along the length of the gut. Our understanding of human GALT is limited due to a lack of protocols for their isolation. Here we describe a technique that, uniquely among intestinal cell isolation protocols, allows identification and isolation of all human GALT, as well as GALT-free intestinal lamina propria (LP). The technique involves the mechanical separation of intestinal mucosa from the submucosa, allowing the identification and isolation of submucosal ILF (SM-ILF), LP-embedded mucosal ILF (M-ILF) and LP free of contaminating lymphoid tissue. Individual SM-ILF, M-ILF and Peyer's patch follicles can be subsequently digested for downstream cellular and molecular characterization. The technique, which takes 4-10 h, will be useful for researchers interested in intestinal immune development and function in health and disease.

Immune Profiling of Human Gut-Associated Lymphoid Tissue Identifies a Role for Isolated Lymphoid Follicles in Priming of Region-Specific Immunity.

The intestine contains some of the most diverse and complex immune compartments in the body. Here we describe a method for isolating human gut-associated lymphoid tissues (GALTs) that allows unprecedented profiling of the adaptive immune system in submucosal and mucosal isolated lymphoid follicles (SM-ILFs and M-ILFs, respectively) as well as in GALT-free intestinal lamina propria (LP). SM-ILF and M-ILF showed distinct patterns of distribution along the length of the intestine, were linked to the systemic circulation through MAdCAM-1+ high endothelial venules and efferent lymphatics, and had immune profiles consistent with immune-inductive sites. IgA sequencing analysis indicated that human ILFs are sites where intestinal adaptive immune responses are initiated in an anatomically restricted manner. Our findings position ILFs as key inductive hubs for regional immunity in the human intestine, and the methods presented will allow future assessment of these compartments in health and disease.

Intestinal barrier integrity and inflammatory bowel disease: Stem cell-based approaches to regenerate the barrier.

Disruption of normal barrier function is a fundamental factor in the pathogenesis of inflammatory bowel disease, which includes increased epithelial cell death, modified mucus configuration, altered expression and distribution of tight junction proteins, along with a decreased expression of antimicrobial peptides. Inflammatory bowel disease is associated with life-long morbidity for affected patients, and both the incidence and prevalence is increasing globally, resulting in substantial economic strain for society. Mucosal healing and re-establishment of barrier integrity are associated with clinical remission, as well as with an improved patient outcome. Hence, these factors are vital treatment goals, which conventionally are achieved by a range of medical treatments, although none are effective in all patients, resulting in several patients still requiring surgery at some point. Therefore, novel treatment strategies to accomplish mucosal healing and to re-establish normal barrier integrity in inflammatory bowel disease are warranted, and luminal stem cell-based approaches might have an intriguing potential. Transplantation of in vitro expanded intestinal epithelial stem cells derived either directly from mucosal biopsies or from directed differentiation of human pluripotent stem cells may constitute complementary treatment options for patients with mucosal damage, as intestinal epithelial stem cells are multipotent and may give rise to all epithelial cell types of the intestine. This review provides the reader with a comprehensive state-of-the-art overview of the intestinal barrier's role in healthy and diseased states, discussing the clinical application of stem cell-based approaches to accomplish mucosal healing in inflammatory bowel disease.

YAP/TAZ-Dependent Reprogramming of Colonic Epithelium Links ECM Remodeling to Tissue Regeneration.

Tissue regeneration requires dynamic cellular adaptation to the wound environment. It is currently unclear how this is orchestrated at the cellular level and how cell fate is affected by severe tissue damage. Here we dissect cell fate transitions during colonic regeneration in a mouse dextran sulfate sodium (DSS) colitis model, and we demonstrate that the epithelium is transiently reprogrammed into a primitive state. This is characterized by de novo expression of fetal markers as well as suppression of markers for adult stem and differentiated cells. The fate change is orchestrated by remodeling the extracellular matrix (ECM), increased FAK/Src signaling, and ultimately YAP/TAZ activation. In a defined cell culture system recapitulating the extracellular matrix remodeling observed in vivo, we show that a collagen 3D matrix supplemented with Wnt ligands is sufficient to sustain endogenous YAP/TAZ and induce conversion of cell fate. This provides a simple model for tissue regeneration, implicating cellular reprogramming as an essential element.

Culturing human intestinal stem cells for regenerative applications in the treatment of inflammatory bowel disease.

Both the incidence and prevalence of inflammatory bowel disease (IBD) is increasing globally; in the industrialized world up to 0.5% of the population are affected and around 4.2 million individuals suffer from IBD in Europe and North America combined. Successful engraftment in experimental colitis models suggests that intestinal stem cell transplantation could constitute a novel treatment strategy to re-establish mucosal barrier function in patients with severe disease. Intestinal stem cells can be grown in vitro in organoid structures, though only a fraction of the cells contained are stem cells with regenerative capabilities. Hence, techniques to enrich stem cell populations are being pursued through the development of multiple two-dimensional and three-dimensional culture protocols, as well as co-culture techniques and multiple growth medium compositions. Moreover, research in support matrices allowing for efficient clinical application is in progress. In vitro culture is accomplished by modulating the signaling pathways fundamental for the stem cell niche with a suitable culture matrix to provide additional contact-dependent stimuli and structural support. The aim of this review was to discuss medium compositions and support matrices for optimal intestinal stem cell culture, as well as potential modifications to advance clinical use in IBD.

Circulating Cytokines and Cytokine Receptors in Infliximab Treatment Failure Due to TNF-α Independent Crohn Disease.

The inflammatory response at infliximab (IFX) treatment failure due to tumor necrosis factor (TNF)-α-independent Crohn disease activity is unknown. This is an exploratory, hypothesis-generating study based on samples collected in a clinical trial among patients failing conventional IFX dosages and treated with an intensified IFX regimen for 12 weeks. Patients with clinical response at week 12, as defined by a reduction of Crohn disease activity index by ≥70, were considered to suffer from nonimmune pharmacokinetic (PK) treatment failure (n = 18), and nonresponders had a presumed pharmacodynamic (PD) failure due to non-TNF-driven disease (n = 8). Patients failing IFX due to functional anti-IFX antibodies (n = 2) were excluded. The study population also comprised a group of 12 patients in long-term remission on IFX. A functional cell-based reporter gene assay was applied to measure IFX and anti-IFX antibodies. Circulating cytokines and cytokine receptors were assessed by enzyme-linked immunosorbent assay: granulocyte-macrophage colony-stimulating factor, interferon-γ, interleukin (IL)-1α, IL-1ß, IL-1Ra, IL-6, IL-10, IL-12p70, soluble TNF receptor (sTNF-R) 1, sTNF-R2, IL-17A, and monocyte chemotactic protein 1. The IFX levels were similar between patients with IFX failure caused by nonimmune PK or PD at treatment failure (median 1.4 vs 2.4 µg/mL; P = 0.52), during treatment intensification (8.1 vs 5.6; P = 0.85), and after 12 weeks (8.8 vs 7.7; P = 0.93), congruent with nonresponders failing IFX due to predominantly TNF-α-independent signaling pathways in their disease. Cytokine and cytokine receptor levels were comparable between patients with nonimmune PK failure and PD failure at time of manifestation of IFX failure, but with higher IL-6 and sTNF-R2 levels among IFX treatment failures as compared with patients in remission (IL-6 median 3.6 vs <3.1 pg/mL; P = 0.03; sTNF-R2 3207 vs 2547 pg/mL; P = 0.01). IL-6 and sTNF-R2 were lower after 12 weeks in nonimmune PK failures than in PD failures (<3.1 vs 4.0; P = 0.02; 3209 vs 4740; P = 0.04, respectively), and were measured at levels comparable with patients in remission. Further, trends of decreased IL-6 and sTNF-R2 levels among nonimmune PK failures during IFX intensification (P < 0.05 and P = 0.12) were observed. These observations indicate that IL-6 and sTNF-R2 are of potential relevance in driving the inflammatory response in IFX refractory Crohn disease caused by TNF-α-independent disease activity.

Objective Quantification of Immune Cell Infiltrates and Epidermal Proliferation in Psoriatic Skin: A Comparison of Digital Image Analysis and Manual Counting.

Digital pathology and image analysis have developed extensively during the last couple of years. Especially the advance in whole-slide scanning, software, and computer processing makes it possible to apply these methods in tissue-based research. Today this task is dominated by tedious manual assessments by pathologists with the interobserver and intraobserver variation this includes. Automated quantitative assessment of immunohistochemical staining has the potential to objectively extract numerical measures from cell and tissue structures, and allows efficient high throughput analysis in clinical research. Published data of manual cell counts in psoriatic skin samples were in this study reevaluated using the digital image analysis (DIA) software. Whole slides immunohistochemically stained for CD3, CD4, CD8, CD45R0, and Ki-67 were scanned and quantitatively evaluated using simple threshold analysis. Regression analysis with R values in the range of 0.85 to 0.95 indicates a good correlation between the manual count of cell numbers and the staining density obtained by automated DIA. Moreover, we show that the automated image analysis is reliable over a broad range of thresholds and that it is robust to differences in staining intensities and hence useful for high throughput analysis. DIA is a viable technical approach for automated cell quantification. Its output highly correlates to the conventional manual cell counting and hence allows for increasing the throughput and reducing the analysis time significantly.

Anti-Angiogenic Drugs in the Treatment of Metastatic Renal Cell Carcinoma: Advances in Clinical Application.

The current paradigm in attempting to treat metastatic renal cell carcinoma (mRCC) is a first line treatment with a vascular endothelial growth factor (VEGF) antagonist and second and subsequent treatments with either a vascular endothelial growth factor receptor (VEGFR) or an mTOR (mammalian Target of Rapamycin) inhibitor, while conventional chemotherapeutic and hormonal treatments do not play a role in the management of mRCC. Several drugs directed against VEGF and VEGFR have been developed in recent times. Phase III data validates sunitinib, pazopanib and sorafenib as the best-supported drugs in firstline therapy. Second-line treatment possibilities include axitinib, everolimus and sorafenib. Choosing the right combination of first and second line treatments, however, is difficult, because the success of treatment depends on the precondition of the patient. Hence, biomarkers indicating the best choice of therapy in individual patients are searched and newer trials are set to determine the role of surgery and vaccination together with anti-angiogenic drugs in the treatment of mRCC. In this review, current guidelines in mRCC management are summarized and possibilities of future personalized therapies are pointed out.

Inhibitors of apoptosis (IAPs) regulate intestinal immunity and inflammatory bowel disease (IBD) inflammation.

The inhibitor of apoptosis (IAP) family members, notably cIAP1, cIAP2, and XIAP, are critical and universal regulators of tumor necrosis factor (TNF) mediated survival, inflammatory, and death signaling pathways. Furthermore, IAPs mediate the signaling of nucleotide-binding oligomerization domain (NOD)1/NOD2 and other intracellular NOD-like receptors in response to bacterial pathogens. These pathways are important to the pathogenesis and treatment of inflammatory bowel disease (IBD). Inactivating mutations in the X-chromosome-linked IAP (XIAP) gene causes an immunodeficiency syndrome, X-linked lymphoproliferative disease type 2 (XLP2), in which 20% of patients develop severe intestinal inflammation. In addition, 4% of males with early-onset IBD also have inactivating mutations in XIAP. Therefore, the IAPs play a greater role in gut homeostasis, immunity and IBD development than previously suspected, and may have therapeutic potential.

Transcriptional analysis of left-sided colitis, pancolitis, and ulcerative colitis-associated dysplasia.

BACKGROUND: It is unknown why patients with extensive ulcerative colitis (UC) have a higher risk of colorectal cancer compared with patients with left-sided UC. This study characterizes the inflammatory processes in left-sided UC, pancolitis, and UC-associated dysplasia at the transcriptional level to identify potential biomarkers and transcripts of importance for the carcinogenic behavior of chronic inflammation. METHODS: The Affymetrix GeneChip Human Genome U133 Plus 2.0 was applied on colonic biopsies from UC patients with left-sided UC, pancolitis, dysplasia, and controls. Reverse transcription polymerase chain reaction and immunohistochemistry were performed for validating selected transcripts in the initial cohort and in 2 independent cohorts of patients with UC. Microarray data were analyzed by principal component analysis, and reverse transcription polymerase chain reaction and immunohistochemistry data by the Wilcoxon's rank-sum test. RESULTS: The principal component analysis results revealed separate clusters for left-sided UC, pancolitis, dysplasia, and controls. Close clustering of dysplastic and pancolitic samples indicated similarities in gene expression. Indeed, 101 and 656 parallel upregulated and downregulated transcripts, respectively, were identified in specimens from dysplasia and pancolitis. Validation of selected transcripts hereof identified insulin receptor alpha (INSRA) and MAP kinase interacting serine/threonine kinase 2 (MKNK2) with an enhanced expression in dysplasia compared with left-sided UC and controls, whereas laminin γ2 (LAMC2) was found with a lower expression in dysplasia compared with the remaining 3 groups. CONCLUSIONS: This study demonstrates pancolitis and left-sided UC as distinct inflammatory processes at the transcriptional level, and identifies INSRA, MKNK2, and LAMC2 as potential critical transcripts in the inflammation-driven preneoplastic process of UC.

Transplantation of expanded fetal intestinal progenitors contributes to colon regeneration after injury.

Regeneration and homeostasis in the adult intestinal epithelium is driven by proliferative resident stem cells, whose functional properties during organismal development are largely unknown. Here, we show that human and mouse fetal intestine contains proliferative, immature progenitors, which can be expanded in vitro as Fetal Enterospheres (FEnS). A highly similar progenitor population can be established during intestinal differentiation of human induced pluripotent stem cells. Established cultures of mouse fetal intestinal progenitors express lower levels of Lgr5 than mature progenitors and propagate in the presence of the Wnt antagonist Dkk1, and new cultures can be induced to form mature intestinal organoids by exposure to Wnt3a. Following transplantation in a colonic injury model, FEnS contribute to regeneration of colonic epithelium by forming epithelial crypt-like structures expressing region-specific differentiation markers. This work provides insight into mechanisms underlying development of the mammalian intestine and points to future opportunities for patient-specific regeneration of the digestive tract.

The safety of osmotically acting cathartics in colonic cleansing.

Efficient cleansing of the colon before a colonoscopy or a radiological examination is essential. The osmotically acting cathartics (those given the Anatomical Therapeutic Chemical code A06AD) currently used for this purpose comprise products based on three main substances: sodium phosphate, combinations of polyethylene glycol and electrolyte lavage solutions (PEG-ELS), and magnesium citrate. All these preparations give adequate cleansing results and have similar profiles in terms of the frequency and type of mild to moderate adverse effects. However, serious adverse events, such as severe hyperphosphatemia and irreversible kidney damage owing to acute phosphate nephropathy, have been reported after use of sodium-phosphate-based products. The aim of this Review is to provide an update on the potential safety issues related to the use of osmotically acting cathartics, especially disturbances of renal function and water and electrolyte balance. The available evidence indicates that PEG-ELS-based products are the safest option. Magnesium-citrate-based, hypertonic products should be administered with caution to elderly individuals and patients who are prone to develop disturbances in water and electrolyte balance. Sodium-phosphate-based products can occasionally cause irreversible kidney damage and should not be routinely used in bowel-cleansing procedures.

Metabonomics in ulcerative colitis: diagnostics, biomarker identification, and insight into the pathophysiology.

Nuclear magnetic resonance (NMR) spectroscopy and appropriate multivariate statistical analyses have been employed on mucosal colonic biopsies, colonocytes, lymphocytes, and urine from patients with ulcerative colitis (UC) and controls in order to explore the diagnostic possibilities, define new potential biomarkers, and generate a better understanding of the pathophysiology. Samples were collected from patients with active UC (n = 41), quiescent UC (n = 33), and from controls (n = 25) and analyzed by NMR spectroscopy. Data analysis was carried out by principal component analysis and orthogonal-projection to latent structure-discriminant analysis using the SIMCA P+11 software package (Umetrics, Umea, Sweden) and Matlab environment. Significant differences between controls and active UC were discovered in the metabolic profiles of biopsies and colonocytes. In the biopsies from patients with active UC higher levels of antioxidants and of a range of amino acids, but lower levels of lipid, glycerophosphocholine (GPC), myo-inositol, and betaine were found, whereas the colonocytes only displayed low levels of GPC, myo-inositol and choline. Interestingly, 20% of inactive UC patients had similar profiles to those who were in an active state. This study demonstrates the possibilities of metabonomics as a diagnostic tool in active and quiescent UC and provides new insight into pathophysiologic mechanisms.

Attenuated apoptosis response to Fas-ligand in active ulcerative colitis.

BACKGROUND: From mainly carcinoma cell line studies, apoptosis has been thought to play a major role in the pathogenesis of ulcerative colitis (UC). Apoptosis has been suggested to be due to a Fas ligand / Fas receptor interaction, but has never been studied in cells from patients with active UC. The aim was to investigate both the spontaneous and the cell death receptor ligand-induced apoptosis in UC. METHODS: Twenty patients with UC and 16 control subjects who underwent routine colonoscopy either for the control or surveillance of their disease or where the diagnosis of irritable bowel syndrome was subsequently reached were included. Cultures of isolated colonic crypts were obtained from biopsies and cultured for 4 to 16 hours with Fas ligand or Fas ligand and costimulation with interferon-gamma (IFN-gamma). Control experiments were performed on HT29 cells. Apoptosis was assessed by independent methods. RESULTS: Isolated colonocytes from healthy subjects or patients with remission in UC had a dose-dependent response to Fas ligand. This response was abolished in patients with active UC (P < 0.002), and costimulation with IFN-gamma did not alter this response. Patients with active UC had an increased apoptosis rate of 9.5% compared with controls (P < 0.05). CONCLUSIONS: The current study indicates that colonocytes do not respond to cytokine exposure and inflammation by an increased vulnerability, as previously thought. Colonocytes seem to activate cytoprotective programs in response to inflammation. Apart from supporting the regeneration process during inflammation, this response could additionally cause an increased susceptibility to neoplastic transformation.

Technology insight: metabonomics in gastroenterology-basic principles and potential clinical applications.

Metabonomics-the study of metabolic changes in an integrated biologic system-is an emerging field. This discipline joins the other 'omics' (genomics, transcriptomics and proteomics) to give rise to a comprehensive, systems-biology approach to the evaluation of holistic in vivo function. Metabonomics, especially when based on nuclear magnetic resonance spectroscopy, has the potential to identify biomarkers and prognostic factors, enhance clinical diagnosis, and expand hypothesis generation. As a consequence, the use of metabonomics has been extensively explored in the past decade, and applied successfully to the study of human diseases, toxicology, microbes, nutrition, and plant biology. This Review introduces the basic principles of nuclear magnetic resonance spectroscopy and commonly used tools for multivariate data analysis, before considering the applications and future potential of metabonomics in basic and clinical research, with emphasis on applications in the field of gastroenterology.