Combining TNFSF15 and ASCA IgA can be used as a predictor for the stenosis/perforating phenotype of Crohn's disease

Interaction of Th17 differentiations-related gene polymorphisms and environmental factors contributing to the disease classification, complications, and surgical risks of Crohn's disease in the Chinese Han population

OBJECTIVES

Few studies have been conducted on gene-environment interactions in the Chinese population with Crohn's disease (CD). We aimed to investigate the association between single nucleotide polymorphisms (SNPs) on the T helper 17 (Th17) cell and CD susceptibility/performance in Chinese individuals.

METHODS

We conducted a case-control and case-only study at the Peking Union Medical College Hospital. Four SNPs related to the Th17 cell pathway genes were prioritized, including rs2284553 (interferon gamma receptor 2), rs7517847 (interleukin 23 receptor), rs7773324 (interferon regulatory factor 4), and rs4263839 (tumor necrosis factor superfamily 15). SNP frequency was calculated, and gene-environment interaction was assessed by multifactor dimensionality reduction analysis.

RESULTS

Altogether 159 CD patients and 316 healthy controls were included. All analyzed SNPs were found in Hardy-Weinberg equilibrium (P > 0.05). The frequency of rs2284553-A allele and rs4263839-A allele were lower in CD patients compared with controls (P < 0.05). While the rs4263839-A allele was more prevalent in ileocolonic CD patients than in those with isolated small intestinal or colonic disease (P = 0.035). Gene-environment interactions revealed associations between rs2284553 and breastfeeding, sunshine exposure, and fridge-stored food, affecting age at diagnosis, intestinal involvement, and intestinal stricture. Interaction of rs4263839 and breastfeeding influenced small intestinal lesions and intestinal stricture in CD.

CONCLUSIONS

This study provided information on the genetic background in Chinese CD patients. Incorporating these SNPs into predictive models may improve risk assessment and outcome prediction. Gene-environment interaction contributes to the understanding of CD pathogenesis.

Research-Based Product Innovation to Address Critical Unmet Needs of Patients with Inflammatory Bowel Diseases

Despite progress in recent decades, patients with inflammatory bowel diseases face many critical unmet needs, demonstrating the limitations of available treatment options. Addressing these unmet needs will require interventions targeting multiple aspects of inflammatory bowel disease pathology, including disease drivers that are not targeted by available therapies. The vast majority of late-stage investigational therapies also focus primarily on a narrow range of fundamental mechanisms. Thus, there is a pressing need to advance to clinical stage differentiated investigational therapies directly targeting a broader range of key mechanistic drivers of inflammatory bowel diseases. In addition, innovations are critically needed to enable treatments to be tailored to the specific underlying abnormal biological pathways of patients; interventions with improved safety profiles; biomarkers to develop prognostic, predictive, and monitoring tests; novel devices for nonpharmacological approaches such as minimally invasive monitoring; and digital health technologies. To address these needs, the Crohn's & Colitis Foundation launched IBD Ventures, a venture philanthropy-funding mechanism, and IBD Innovate®, an innovative, product-focused scientific conference. This special IBD Innovate® supplement is a collection of articles reflecting the diverse and exciting research and development that is currently ongoing in the inflammatory bowel disease field to deliver innovative and differentiated products addressing critical unmet needs of patients. Here, we highlight the pipeline of new product opportunities currently advancing at the preclinical and early clinical development stages. We categorize and describe novel and differentiated potential product opportunities based on their potential to address the following critical unmet patient needs: (1) biomarkers for prognosis of disease course and prediction/monitoring of treatment response; (2) restoration of eubiosis; (3) restoration of barrier function and mucosal healing; (4) more effective and safer anti-inflammatories; (5) neuromodulatory and behavioral therapies; (6) management of disease complications; and (7) targeted drug delivery.

Serological markers facilitate the diagnosis of Crohn's disease

Background and aim: The diagnosis of Crohn's disease (CD) is challenging. Ongoing search for biomarkers to facilitate the diagnosis is a worthwhile endeavor. The aim of this study was to explore the role of serological markers in the diagnosis of CD at an inflammatory bowel disease (IBD) referral center.Methods: This was a retrospective study including 196 suspected CD patients. The expression of ASCA-IgG, ASCA-IgA, AYMA-IgG, AYCA-IgA, FI2Y-IgG, and pANCA in the patient's serum was determined by enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence (IF).Results: ASCA was a relatively specific marker for CD (p = 0.0005), but not AYMA-IgG, AYCA-IgA, F12Y-IgG (p = 0.5936, 0.7974, 0.1085, respectively). However, a high sensitivity of 96.77% (95% CI 90.19%-99.83%) was noted for ASCA+/FI2Y+ to identify CD patients among the suspected cases, albeit with low PPV. The more combinations of serological markers, the higher sensitivity, and NPV. No correlation was found between the age of onset or disease location and the expression of ASCA, AYMA, AYCA, FI2Y, or pANCA. There was no significant difference between the expression of ASCA and the disease behavior at diagnosis (p = 0.3307). However, a decreased proportion of AYMA+ CD patients was found in those who received surgery compared with their non-surgical counterparts (p = 0.0488).Conclusions: ASCA was found to be the most accurate serological marker for the differential diagnosis of CD. Combinations of ASCA, AYMA, AYCA, and FI2Y improved diagnostic accuracy of CD.

Gut microbial transcytosis induced by tumor necrosis factor-like 1A-dependent activation of a myosin light chain kinase splice variant contributes to IBD

Inflammatory bowel disease (IBD) is characterized by abnormal host-microbe interactions. Proinflammatory cytokine IFNγ and a novel TNF superfamily member, TL1A, have been implicated in epithelial barrier dysfunction. The divergent regulatory mechanisms of transcellular versus paracellular hyperpermeability remain poorly understood. Intestinal epithelia express two splice variants of long myosin light chain kinase (MLCK), of which the full-length MLCK1 differ from the shorter isoform MLCK2 by a Src kinase phosphorylation site. The aim was to investigate the roles of MLCK splice variants in gut barrier defects under proinflammatory stress. Upregulated expression of TL1A, IFNγ, and two MLCK variants was observed in human IBD biopsy specimens. The presence of intraepithelial bacteria preceded tight junction (TJ) damage in dextran sodium sulfate-treated and TL1A-transgenic mouse models. Lack of barrier defects was observed in long MLCK(-/-) mice. TL1A induced MLCK-dependent terminal web (TW) contraction, brush border fanning, and transepithelial bacterial internalization. The bacterial taxa identified in the inflamed colonocytes included Escherichia, Enterococcus, Staphylococcus,and Lactobacillus. Recombinant TL1A and IFNγ at low doses induced PI3K/Akt/MLCK2-dependent bacterial endocytosis, whereas high-dose IFNγ caused TJ opening via the iNOS/Src/MLCK1 axis. Bacterial internalization was recapitulated in MLCK-knockout cells individually expressing MLCK2 but not MLCK1. Immunostaining showed different subcellular sites of phosphorylated MLC localized to the TJ and TW in the MLCK1- and MLCK2-expressing cells, respectively. In conclusion, proinflammatory cytokines induced bacterial influx through transcellular and paracellular routes via divergent pathways orchestrated by distinct MLCK isoforms. Bacterial transcytosis induced by TL1A may be an alternative route causing symptom flares in IBD.

Epidemiology of fibrostenosing inflammatory bowel disease

Fibrostenosis occurs in both Crohn's disease (CD) and ulcerative colitis (UC). Up to 21% of patients with CD present with strictures at diagnosis, while the rate of stenosis varies from 1% to 11% in UC. Despite the increasing use of immunomodulators and biologics in treatment, there has been no decrease in the rate of progression from inflammatory to complicated disease phenotypes (either stricturing or penetrating). The presence of stenosis is an independent risk factor for surgery in patients with CD, who are at a risk of postoperative recurrence at a rate of up to 55% at 10 years after surgery. Patients with inflammatory bowel disease (IBD) strictures are at risk of malignant transformation. Thus, surveillance colonoscopy should be offered to this group of patients. Several risk factors for the development of stricture have been identified. In CD, patients aged less than 40-years old, with perianal disease at diagnosis, who need steroids at the first flare up or have ileal disease are at the risk of developing strictures; while in UC, patients with extensive colitis and long-standing disease are at risk. Recently, microbiota signatures have also been identified as markers for stricture development. The presence of Ruminococcus spp. is associated with the development of stricture in pediatric patients with CD. In this review, we highlight the epidemiology, risk factors and natural history of fibrostenosing IBD.

Effect of Loureirin B on Crohn's disease rat model induced by TNBS via IL-6/STAT3/NF-κB signaling pathway

Background

Crohn’s disease (CD) is a chronic relapsing form of inflammatory bowel disease, seriously threatening human beings health. However, the pathogenesis of CD is still unclear and there is no specific effective drug for treatment of CD. Resina Donis (RD) obtained from Dracaena cochinchinensis (Lour.) S. C. Chen (Liliaceae), has been used for the treatment of CD clinically. Loureirin B (LB) is one of the most important chemical compositions and physiologically active ingredients of resina draconis. It has the molecular structure propan-1-one, 1-(4-hydroxyphenyl)-3-(2,4,6-trimethoxyphenyl)-1-(4-hydroxyphenyl)-3-(2,4,6-trimethoxyphenyl) propan-1-one. The aim of this study was to investigate the effect of LB on CD and explore the underlying mechanisms.

Methods and results

In this study, the result demonstrated that LB prolonged the survival time of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced rats and alleviated colonic damage in a dose dependent manner. Besides, LB remarkably ameliorated TNBS-induced inflammatory response via regulation of cytokines in the colonic tissues. Moreover, LB could reverse the established fibrosis and impede the accumulation infiltration, and improve the apoptosis induced by TNBS in a dose dependent manner. Further, LB dramatically suppressed TNBS-induced the activation of IL-6/STAT3/NF-κB signaling pathway.

Conclusions

These findings suggested that LB could be beneficial regarding ameliorating TNBS-induced CD, which may represent a novel approach to treat CD and provide an alternative choice for disorders associated with CD.

Genetic Studies of Inflammatory Bowel Disease-Focusing on Asian Patients

The pathogenesis of inflammatory bowel disease (IBD) is not well-understood; however, increased and persistent intestinal inflammation, due to inappropriate immune responses that are caused by interactions between genetic factors, gut microbiota, and environmental factors, are thought to lead to IBD. Various studies have identified more than 240 genetic variants related to IBD. These genetic variants are involved in innate and adaptive immunity, autophagy, defective bacterial handing, interleukin-23 and 10 signaling, and so on. According to several epidemiological and clinical studies, the phenotypes and clinical course of IBD differ between Asians and Europeans. Although the risk loci for IBD typically overlap between Asians and Westerners, genetic heterogeneity has been detected in many loci/genes, such as NOD2/CARD15, TNFSF15 and human leukocyte antigen, contributing to the risk of IBD. Thus, although common pathways exist between Westerners and Asians in the development of IBD, their significance may differ for individual pathways. Although genetic studies are not universally applicable in the clinical field, they may be useful for diagnosing and categorizing IBD, predicting therapeutic responses and toxicity to drugs, and assessing prognosis by risk modeling, thereby enabling precision medicine for individual patients.

TL1A (TNFSF15) and DR3 (TNFRSF25): A Co-stimulatory System of Cytokines With Diverse Functions in Gut Mucosal Immunity

TL1A and its functional receptor DR3 are members of the TNF/TNFR superfamilies of proteins. Binding of APC-derived TL1A to lymphocytic DR3 provides co-stimulatory signals for activated lymphocytes. DR3 signaling affects the proliferative activity of and cytokine production by effector lymphocytes, but also critically influences the development and suppressive function of regulatory T-cells. DR3 was also found to be highly expressed by innate lymphoid cells (ILCS), which respond to stimulation by TL1A. Several recent studies with transgenic and knockout mice as well as neutralizing or agonistic antibodies for these two proteins, have clearly shown that TL1A/DR3 are important mediators of several chronic immunological disorders, including Inflammatory Bowel Disease (IBD). TL1A and DR3 are abundantly localized at inflamed intestinal areas of patients with IBD and mice with experimental ileitis or colitis and actively participate in the immunological pathways that underlie mucosal homeostasis and intestinal inflammation. DR3 signaling has demonstrated a dichotomous role in mucosal immunity. On the one hand, during acute mucosal injury it exerts protective functions by ameliorating the severity of acute inflammatory responses and facilitating tissue repair. On the other hand, it critically participates in the pro-inflammatory pathways that underlie chronic inflammatory responses, such as those that take place in IBD. These effects are mediated through modulation of the relative mucosal abundance and function of Th1, Th2, Th17, Th9, and Treg lymphocytes, but also of all types of ILCs. Recently, an important role was demonstrated for TL1A/DR3 as potential mediators of intestinal fibrosis that is associated with the presence of gut inflammation. These accumulating data have raised the possibility that TL1A/DR3 pathways may represent a valid therapeutic target for chronic immunological diseases. Nevertheless, applicability of such a therapeutic approach will greatly rely on the net result of TL1A/DR3 manipulation on the various cell populations that will be affected by this approach.

Microbiota-Induced TNF-like Ligand 1A Drives Group 3 Innate Lymphoid Cell-Mediated Barrier Protection and Intestinal T Cell Activation during Colitis

Inflammatory bowel disease (IBD) results from a dysregulated interaction between the microbiota and a genetically susceptible host. Genetic studies have linked TNFSF15 polymorphisms and its protein TNF-like ligand 1A (TL1A) with IBD, but the functional role of TL1A is not known. Here, we found that adherent IBD-associated microbiota induced TL1A release from CX3CR1+ mononuclear phagocytes (MNPs). Using cell-specific genetic deletion models, we identified an essential role for CX3CR1+MNP-derived TL1A in driving group 3 innate lymphoid cell (ILC3) production of interleukin-22 and mucosal healing during acute colitis. In contrast to this protective role in acute colitis, TL1A-dependent expression of co-stimulatory molecule OX40L in MHCII+ ILC3s during colitis led to co-stimulation of antigen-specific T cells that was required for chronic T cell colitis. These results identify a role for ILC3s in activating intestinal T cells and reveal a central role for TL1A in promoting ILC3 barrier immunity during colitis.

SP110 Polymorphisms Are Genetic Markers for Vulnerability to Latent and Active Tuberculosis Infection in Taiwan

One-fourth of the human population is estimated to have been exposed to Mycobacterium tuberculosis (Mtb) and carries the infection in its latent form. This latent infection presents a lifelong risk of developing active tuberculosis (TB) disease, and persons with latent TB infection (LTBI) are significant contributors to the pool of active TB cases. Genetic polymorphisms among hosts have been shown to contribute to the outcome of Mtb infection. The SP110 gene, which encodes an interferon-induced nuclear protein, has been shown to control host innate immunity to Mtb infection. In this study, we provide experimental data demonstrating the ability of the gene to control genetic susceptibility to latent and active TB infection. Genetic variants of the SP110 gene were investigated in the Taiwanese population (including 301 pulmonary TB patients, 68 LTBI individuals, and 278 healthy household contacts of the TB patients), and their association with susceptibility to latent and active TB infection was examined by performing an association analysis in a case-control study. We identified several SNPs (rs7580900, rs7580912, rs9061, rs11556887, and rs2241525) in the SP110 gene that are associated with susceptibility to LTBI and/or TB disease. Our studies further showed that the same SNPs may have opposite effects on the control of susceptibility to LTBI versus TB. In addition, our analyses demonstrated that the SP110 rs9061 SNP was associated with tumor necrosis factor-α (TNFα) levels in plasma in LTBI subjects. The results suggest that the polymorphisms within SP110 have a role in controlling genetic susceptibility to latent and active TB infection in humans. To the best of our knowledge, this is the first report showing that the SP110 variants are associated with susceptibility to LTBI. Our study also demonstrated that the identified SP110 SNPs displayed the potential to predict the risk of LTBI and subsequent TB progression in Taiwan.

New Biomarkers for Diagnosing Inflammatory Bowel Disease and Assessing Treatment Outcomes

Despite advances in our understanding of the pathophysiology underlying inflammatory bowel disease, there remains a significant need for biomarkers that can differentiate between Crohn's disease and ulcerative colitis with high sensitivity and specificity, in a cost-efficient manner. As the focus on personalized approaches to the delivery of medical treatment increases, new biomarkers are being developed to predict an individual's response to therapy and their overall disease course. In this review, we will outline many of the existing and recently developed biomarkers, detailing their role in the assessment of patients with inflammatory bowel disease. We will identify opportunities for improvement in our biomarkers, including better differentiation between the subtypes of inflammatory bowel disease. We will also discuss new targets and strategies in biomarker development, including combining modalities to create biomarker signatures to improve the ability to predict disease courses and response to therapy among individual patients.

Clinical Utility of Biomarkers in IBD

There is no gold standard for the diagnosis and monitoring of inflammatory bowel diseases (IBD). Biomarkers are useful tools for the management of patients suffering from IBD. However, they should be used only when their additional information is useful for clinical decision-making. In principal, four situations during the management of an individual IBD patient can be discriminated from a clinical standpoint in which biomarkers provide useful information. First, biomarkers may be helpful when the diagnosis of IBD is established and aid in the discrimination between ulcerative colitis (UC) and Crohn's disease (CD) is necessary. Second, biomarkers may be helpful in the prognostic evaluation of IBD severity or disease behavior and for early decisions on the best treatment. The third situation in which biomarkers are useful is the evaluation of disease activity during the disease course, for monitoring and for guidance of ongoing treatment. Finally, the fourth typical situation when biomarkers are of value is after surgery to predict or diagnose a relapse of the disease. From a clinical point of view, it may be more useful to discuss specific biomarkers and their individual value and impact in these four prototypic situations than to sum up advantages and disadvantages for each biomarker isolated from the clinical situation. Therefore, this overview is structured in chapters reflecting those four typical situations during the disease course of IBD patents to critically evaluate the potential and value of each of the biomarkers in the specific situation.

Tumor Necrosis Factor-like Cytokine TL1A and Its Receptors DR3 and DcR3: Important New Factors in Mucosal Homeostasis and Inflammation

Tumor necrosis factor (TNF)-like cytokine 1A (TL1A) is a member of the TNF superfamily of proteins (TNFSF15), which signals through association with death domain receptor 3 (DR3). Decoy receptor 3 (DcR3) competes with DR3 for TL1A binding and inhibits functional signaling. These proteins are significantly upregulated in inflamed intestinal tissues, and their pathogenetic importance for inflammatory bowel disease (IBD) is suggested by accumulating evidence. TL1A/DR3 induce costimulatory signals to activated lymphocytes, including the gut-specific populations of CD4+CD161+ and CD4+CCR9+ cells, affecting all major effector pathways and inducing the mucosal upregulation of Th1, Th2, and Th17 factors. They may also participate in mucosal homeostasis and defense against pathogens through their effects on the development and function of the recently described innate lymphoid cells. T-regulatory lymphocytes highly express DR3, and they respond to TL1A stimulation also. Mechanistic studies by transgenic expression of TL1A, deletion of TL1A or DR3, and therapeutic blockade by anti-TL1A antibodies all support the critical involvement of the corresponding pathways in the pathogenesis of chronic mucosal inflammation. Wide genome association studies have identified IBD-specific polymorphisms in TNFSF15 gene, which have functional implications and serve as poor prognostic factors. Recently, TL1A blockade in mice was presented as a unique pharmacological treatment for the reversal of established intestinal fibrosis. Finally, TL1A/DR3 signaling seems to critically participate in extraintestinal inflammatory conditions that are frequently associated with IBD as part of the gut-joint-skin-eye axis. These converging lines of evidence make TL1A/DR3 a suitable model for personalized approaches to IBD therapy.

Overcoming difficulty in diagnosis and differential diagnosis of Crohn's disease: the potential role of serological and genetic tests

Crohn's disease (CD) represents a heterogeneous group of chronic inflammatory disorders with various phenotypes. Establishing a definite diagnosis of CD should be based upon a combined assessment of clinical, endoscopic, radiological and pathological features. Although segmental disease distribution, transmural inflammation and non-caseating epithelioid granulomas have been considered as a 'hallmarks' for CD, clear diagnosis of CD in some patients has been challenging, due to overlapping endoscopic, radiographic and histologic features with other inflammatory bowel disease-like conditions. Laboratory markers (serological and genetic tests) may provide additional clues for the diagnosis and differential diagnosis of CD. This review focuses on the application of the currently available serological and genomic markers and in diagnosis and differential diagnosis of CD.

Intestinal stricture in Crohn's disease

Crohn's disease (CD) is a disease with chronic inflammation of unknown etiology involving any part of the gastrointestinal tract. The incidence and prevalence of CD are increasing recently in Asia. Half of the CD patients will have intestinal complications, such as strictures or fistulas, within 20 years after diagnosis. Twenty-five percentage of CD patients have had at least one small bowel stricture and 10% have had at least one colonic stricture and lead to significant complications. Most of these patients will require at least one surgery during their lifetime. Early diagnosis and evaluation with adequate managements for the patients can prevent disability and mortality of these patient. Here, we reviewed the current incidence of CD with stricture, the etiology of stricture, and how to diagnose and manage the stricture.