TL1A blocking ameliorates intestinal fibrosis in the T cell transfer model of chronic colitis in mice

TL1A Inhibition in Inflammatory Bowel Disease: A Pipeline Review

Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD) and ulcerative colitis (UC), remains challenging to manage, with a substantial proportion of patients not responding to conventional therapies or developing complications. The tumor necrosis factor (TNF) superfamily member TL1A has emerged as an important player in the pathogenesis of IBD, influencing pathways of inflammation and fibrosis. This leading article reviews the role of TL1A in IBD, evaluates the efficacy of anti-TL1A therapies in clinical trials, and discusses future directions for research and treatment. TL1A is implicated in IBD through its interaction with death domain receptor 3 (DR3), promoting T-cell activation and contributing to both inflammatory responses and fibrotic changes. Phase 2 clinical trials of anti-TL1A agents have demonstrated promising results, showing improvements in endoscopic and histologic outcomes for both UC and CD. Phase 2 and 3 clinical trials are ongoing, which are expected to provide further clarity on the efficacy and safety of TL1A-targeting agents in treating IBD.

The TL1A inhibitors in IBD: what's in the pot?

INTRODUCTION

Inflammatory bowel diseases (IBD), encompassing Crohn's disease (CD) and ulcerative colitis (UC), present ongoing challenges despite advances in pathophysiological understanding and therapeutic options. Current therapies often fail to achieve sustained remission, necessitating exploration of novel treatment targets.

AREAS COVERED

This review explores the role of Tumor Necrosis Factor-like cytokine 1A (TL1A) and its receptor DR3 in IBD pathogenesis, detailing their involvement in mucosal homeostasis and immune modulation. Recent studies on TL1A inhibitors highlight their potential in mitigating inflammation and fibrosis in IBD.

EXPERT OPINION

TL1A inhibition emerges as a promising therapeutic strategy, supported by encouraging outcomes in clinical trials for moderate to severe IBD. Future research may elucidate TL1A's broader impact on immunity, epithelial integrity and fibrosis, offering new avenues for therapeutic intervention and biomarker discovery. Ongoing phase 3 trials are pivotal in assessing TL1A inhibitors as effective and safe treatments for IBD. Additionally, exploration of TL1A's role in fibrosis-associated complications and its potential as a biomarker for treatment response holds promise for personalized medicine approaches. Consideration of TL1A inhibition in concurrent immune-mediated inflammatory diseases suggests broader therapeutic implications beyond gastrointestinal manifestations of IBD.

Mechanisms of Insulin Signaling as a Potential Therapeutic Method in Intestinal Diseases

Gastrointestinal diseases are becoming a growing public health problem. One of them is inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD). The incidence of IBD is increasing in developing countries and declining in developed countries, affecting people of all ages. Researchers have been exploring new treatment options including insulin signaling pathways in the inflammation of the gastrointestinal tract. It seems that a better understanding of the mechanism of IGF-1, GLP-1 and TL1A on the gut microbiota and inflammation may provide new advances in future therapeutic strategies for patients with IBD, but also other intestinal diseases. This review aims to synthesize insights into the effects of GLP, IGF and anti-TL1A on inflammation and the gut microbiota, which may enable their future use in therapy for people with intestinal diseases.

TNFSF15 variant predicts disease progression in Chinese patients with Crohn's disease

Background

The genetic variant of tumor necrosis factor superfamily member 15 (TNFSF15) is associated with Crohn's disease (CD) and the development of intestinal fibrosis and stricturing. We aimed to investigate its predictive role in disease progression and the impact of ileal fibrosis-associated protein expression in Chinese patients with CD.

Methods

We genotyped the single nucleotide polymorphism rs6478109 within the TNFSF15 gene in 428 CD patients and 450 health controls to assess its association with CD. Genotype-phenotype correlation analyses were performed. Mucosal samples from non-diseased terminal ileum were analyzed for TL1A and fibrosis-associated protein expression using western blot and immunohistochemistry.

Results

The G allele frequency of rs6478109 was significantly higher among CD patients compared with health controls (63.3% vs. 46.7%, P < 0.001). Patients with GG genotype were more predisposed to develop the stricturing phenotype, compared with those with AA + AG genotypes with a hazard ratio of 1.426 (95% confidence interval: 1.029-1.977, P = 0.033). This trend was similarly observed in patients utilizing biological agents, with a hazard ratio of 4.396 (95% confidence interval: 1.780-10.854, P = 0.001). Furthermore, increased TL1A, pro-fibrotic proteins, and TGFβ1/Smad3 pathway activation were observed in non-diseased ileal mucosa of patients with GG genotype compared with those with AA genotype.

Conclusions

The TNFSF15 risk genotype GG could promote the expression of pro-fibrotic proteins and may serve as a predictor for stricturing CD.

Targeting TNF/TNFR superfamilies in immune-mediated inflammatory diseases

Dysregulated signaling from TNF and TNFR proteins is implicated in several immune-mediated inflammatory diseases (IMIDs). This review centers around seven IMIDs (rheumatoid arthritis, systemic lupus erythematosus, Crohn's disease, ulcerative colitis, psoriasis, atopic dermatitis, and asthma) with substantial unmet medical needs and sheds light on the signaling mechanisms, disease relevance, and evolving drug development activities for five TNF/TNFR signaling axes that garner substantial drug development interest in these focus conditions. The review also explores the current landscape of therapeutics, emphasizing the limitations of the approved biologics, and the opportunities presented by small-molecule inhibitors and combination antagonists of TNF/TNFR signaling.

The landscape of new therapeutic opportunities for IBD

This chapter presents an overview of the emerging strategies to address the unmet needs in the management of inflammatory bowel diseases (IBD). IBD poses significant challenges, as over half of patients experience disease progression despite interventions, leading to irreversible complications, and a substantial proportion do not respond to existing therapies, such as biologics. To overcome these limitations, we describe a diverse array of novel therapeutic approaches. In the area of immune homeostasis restoration, the focus is on targeting cytokine networks, leukocyte trafficking, novel immune pathways, and cell therapies involving regulatory T cells and mesenchymal stem cells (MSC). Recognizing the critical role of impaired intestinal barrier integrity in IBD, we highlight therapies aimed at restoring barrier function and promoting mucosal healing, such as those targeting cell proliferation, tight junctions, and lipid mediators. Addressing the challenges posed by fibrosis and fistulas, we describe emerging targets for reversing fibrosis like kinase and cytokine inhibitors and nuclear receptor agonists, as well as the potential of MSC for fistulas. The restoration of a healthy gut microbiome, through strategies like fecal microbiota transplantation, rationally defined bacterial consortia, and targeted antimicrobials, is also highlighted. We also describe innovative approaches to gut-targeted drug delivery to enhance efficacy and minimize side effects. Reinforcing these advancements is the critical role of precision medicine, which emphasizes the use of multiomics analysis for the discovery of biomarkers to enable personalized IBD care. Overall, the emerging landscape of therapeutic opportunities for IBD holds great potential to surpass the therapeutic ceiling of current treatments.

Anti-fibrotics in inflammatory bowel diseases: Challenges and successes

Stricture formation leading to obstruction in Crohn's disease (CD) remains one of the largest unmet needs in the field of inflammatory bowel diseases (IBD). Despite this need no selective anti-stricture drug has been approved for use in CD patients. This contrasts with other fibrotic diseases, such as in the lung, liver or kidney, where multiple drug development programs crossed the starting line and two anti-fibrotics are now being approved for pulmonary fibrosis. Strictures are composed of a mix of inflammation, excessive deposition of extracellular matrix (ECM) and smooth muscle hyperplasia, likely all ultimately being responsible for the luminal narrowing driving patient symptoms. Our understanding of the pathogenesis of stricturing CD has evolved and indicates a multifactorial process involving immune and non-immune cells and their soluble mediators. This understanding has rendered target pathways for anti-stricture drug development. Significant progress was made in creating consensus definitions and tools to enable clinical trials with two clinical development programs having been conceived to date. In this chapter, we discuss stricture pathogenesis with a focus on the pathways being tested in clinical trials, and clinical trial endpoints developed for this indication.

The potential of targeting TREM-1 in IBD

Innate immune dysfunction is a hallmark of the pathogenesis of Inflammatory Bowel Disease, both in Crohn's disease and ulcerative colitis. Despite considerable efforts in research to better understand the pathophysiology of IBD and for the development of new therapeutic modalities for IBD patients, there is no therapy specifically targeting the dysregulations of the innate immune response available today in that field. TREM-1 is exclusively expressed by innate immune cells and is an immune amplifier. Its engagement following the primary activation of Pattern Recognition Receptors, including Toll-Like Receptors, triggers the development of a dysregulated and sustained innate immune response, promoting the perpetuation of the inflammatory response in the mucosa of IBD patients, microscopic mucosal tissue alterations, impaired autophagy, impaired epithelial barrier integrity and function, ulcerations, and mucosal damages. In patients, TREM-1 activation is associated with the active status of the disease as well as with severity. Blocking TREM-1 in experimental colitis attenuates the dysregulated innate immune response leading to improved clinical signs. Anti-TREM-1 approaches have the potential of controlling the pathogenic dysregulation of the immune response in IBD by targeting an upstream amplification loop of the activation of innate immunity.

Phase 2 Trial of Anti-TL1A Monoclonal Antibody Tulisokibart for Ulcerative Colitis

BACKGROUND

Tulisokibart is a tumor necrosis factor-like cytokine 1A (TL1A) monoclonal antibody in development for the treatment of moderately to severely active ulcerative colitis. A genetic-based diagnostic test was designed to identify patients with an increased likelihood of response.

METHODS

We randomly assigned patients with glucocorticoid dependence or failure of conventional or advanced therapies for ulcerative colitis to receive intravenous tulisokibart (1000 mg on day 1 and 500 mg at weeks 2, 6, and 10) or placebo. Cohort 1 included patients regardless of status with respect to the test for likelihood of response. Cohort 2 included only patients with a positive test for likelihood of response. The primary analysis was performed in cohort 1; the primary end point was clinical remission at week 12. Patients with a positive test for likelihood of response from cohorts 1 and 2 were combined in prespecified analyses.

RESULTS

In cohort 1, a total of 135 patients underwent randomization. A significantly higher percentage of patients who received tulisokibart had clinical remission than those who received placebo (26% vs. 1%; difference, 25 percentage points; 95% confidence interval [CI], 14 to 37; P<0.001). In cohort 2, a total of 43 patients underwent randomization. A total of 75 patients with a positive test for likelihood of response underwent randomization across both cohorts. Among patients with a positive test for likelihood of response (cohorts 1 and 2 combined), clinical remission occurred in a higher percentage of patients who received tulisokibart than in those who received placebo (32% vs. 11%; difference, 21 percentage points; 95% CI, 2 to 38; P = 0.02). Among all the enrolled patients, the incidence of adverse events was similar in the tulisokibart and placebo groups; most adverse events were mild to moderate in severity.

CONCLUSIONS

In this short-term trial, tulisokibart was more effective than placebo in inducing clinical remission in patients with moderately to severely active ulcerative colitis. (Funded by Prometheus Biosciences, a subsidiary of Merck; ARTEMIS-UC ClinicalTrials.gov number, NCT04996797.).

Inflammation accelerating intestinal fibrosis: from mechanism to clinic

Intestinal fibrosis is a prevalent complication of IBD that that can frequently be triggered by prolonged inflammation. Fibrosis in the gut can cause a number of issues, which continue as an ongoing challenge to healthcare systems worldwide. The primary causes of intestinal fibrosis are soluble molecules, G protein-coupled receptors, epithelial-to-mesenchymal or endothelial-to-mesenchymal transition, and the gut microbiota. Fresh perspectives coming from in vivo and in vitro experimental models demonstrate that fibrogenic pathways might be different, at least to some extent, independent of the ones that influence inflammation. Understanding the distinctive procedures of intestinal fibrogenesis should provide a realistic foundation for targeting and blocking specific fibrogenic pathways, estimating the risk of fibrotic consequences, detecting early fibrotic alterations, and eventually allowing therapy development. Here, we first summarize the inflammatory and non-inflammatory components of fibrosis, and then we elaborate on the underlying mechanism associated with multiple cytokines in fibrosis, providing the framework for future clinical practice. Following that, we discuss the relationship between modernization and disease, as well as the shortcomings of current studies. We outline fibrosis diagnosis and therapy, as well as our recommendations for the future treatment of intestinal fibrosis. We anticipate that the global review will provides a wealth of fresh knowledge and suggestions for future fibrosis clinical practice.

Mechanisms and therapeutic research progress in intestinal fibrosis

Intestinal fibrosis is a common complication of chronic intestinal diseases with the characteristics of fibroblast proliferation and extracellular matrix deposition after chronic inflammation, leading to lumen narrowing, structural and functional damage to the intestines, and life inconvenience for the patients. However, anti-inflammatory drugs are currently generally not effective in overcoming intestinal fibrosis making surgery the main treatment method. The development of intestinal fibrosis is a slow process and its onset may be the result of the combined action of inflammatory cells, local cytokines, and intestinal stromal cells. The aim of this study is to elucidate the pathogenesis [e.g., extracellular matrix (ECM), cytokines and chemokines, epithelial-mesenchymal transition (EMT), differentiation of fibroblast to myofibroblast and intestinal microbiota] underlying the development of intestinal fibrosis and to explore therapeutic advances (such as regulating ECM, cytokines, chemokines, EMT, differentiation of fibroblast to myofibroblast and targeting TGF-β) based on the pathogenesis in order to gain new insights into the prevention and treatment of intestinal fibrosis.

TL1A Promotes Fibrogenesis in Colonic Fibroblasts via the TGF-β1/Smad3 Signaling Pathway

OBJECTIVE

Intestinal fibrosis is a refractory complication of inflammatory bowel disease (IBD). Tumor necrosis factor ligand-related molecule-1A (TL1A) is important for IBD-related intestinal fibrosis in a dextran sodium sulfate (DSS)-induced experimental colitis model. This study aimed to explore the effects of TL1A on human colonic fibroblasts.

METHODS

A trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis model of LCK-CD2-TL1A-GFP transgenic (Tg) or wild-type (WT) mice was established to determine the effect and mechanism of TL1A on intestinal fibrosis. The human colonic fibroblast CCD-18Co cell line was treated concurrently with TL1A and human peripheral blood mononuclear cell (PBMC) supernatant. The proliferation and activation of CCD-18Co cells were detected by BrdU assays, flow cytometry, immunocytochemistry and Western blotting. Collagen metabolism was tested by Western blotting and real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

The level of collagen metabolism in the TNBS+ethyl alcohol (EtOH)/Tg group was greater than that in the TNBS+EtOH/WT group. Transforming growth factor-β1 (TGF-β1) and p-Smad3 in the TNBS+EtOH/Tg group were upregulated as compared with those in the TNBS+EtOH/WT group. The proliferation of CCD-18Co cells was promoted by the addition of human PBMC supernatant supplemented with 20 ng/mL TL1A, and the addition of human PBMC supernatant and TL1A increased CCD-18Co proliferation by 24.4% at 24 h. TL1A promoted cell activation and increased the levels of COL1A2, COL3A1, and TIMP-1 in CCD-18Co cells. Treatment of CCD-18Co cells with TL1A increased the expression of TGF-β1 and p-Smad3.

CONCLUSION

TL1A promotes TGF-β1-mediated intestinal fibroblast activation, proliferation, and collagen deposition and is likely related to an increase in the TGF-β1/Smad3 signaling pathway.

The IRE1α/XBP1 pathway sustains cytokine responses of group 3 innate lymphoid cells in inflammatory bowel disease

Group 3 innate lymphoid cells (ILC3s) are key players in intestinal homeostasis. ER stress is linked to inflammatory bowel disease (IBD). Here, we used cell culture, mouse models, and human specimens to determine whether ER stress in ILC3s affects IBD pathophysiology. We show that mouse intestinal ILC3s exhibited a 24-hour rhythmic expression pattern of the master ER stress response regulator inositol-requiring kinase 1α/X-box-binding protein 1 (IRE1α/XBP1). Proinflammatory cytokine IL-23 selectively stimulated IRE1α/XBP1 in mouse ILC3s through mitochondrial ROS (mtROS). IRE1α/XBP1 was activated in ILC3s from mice exposed to experimental colitis and in inflamed human IBD specimens. Mice with Ire1α deletion in ILC3s (Ire1αΔRorc) showed reduced expression of the ER stress response and cytokine genes including Il22 in ILC3s and were highly vulnerable to infections and colitis. Administration of IL-22 counteracted their colitis susceptibility. In human ILC3s, IRE1 inhibitors suppressed cytokine production, which was upregulated by an IRE1 activator. Moreover, the frequencies of intestinal XBP1s+ ILC3s in patients with Crohn's disease before administration of ustekinumab, an anti-IL-12/IL-23 antibody, positively correlated with the response to treatment. We demonstrate that a noncanonical mtROS-IRE1α/XBP1 pathway augmented cytokine production by ILC3s and identify XBP1s+ ILC3s as a potential biomarker for predicting the response to anti-IL-23 therapies in IBD.

Fibrosis in IBD: from pathogenesis to therapeutic targets

BACKGROUND

Intestinal fibrosis resulting in stricture formation and obstruction in Crohn's disease (CD) and increased wall stiffness leading to symptoms in ulcerative colitis (UC) is among the largest unmet needs in inflammatory bowel disease (IBD). Fibrosis is caused by a multifactorial and complex process involving immune and non-immune cells, their soluble mediators and exposure to luminal contents, such as microbiota and environmental factors. To date, no antifibrotic therapy is available. Some progress has been made in creating consensus definitions and measurements to quantify stricture morphology for clinical practice and trials, but approaches to determine the degree of fibrosis within a stricture are still lacking.

OBJECTIVE

We herein describe the current state of stricture pathogenesis, measuring tools and clinical trial endpoints development.

DESIGN

Data presented and discussed in this review derive from the past and recent literature and the authors' own research and experience.

RESULTS AND CONCLUSIONS

Significant progress has been made in better understanding the pathogenesis of fibrosis, but additional studies and preclinical developments are needed to define specific therapeutic targets.

Growth Factors-Loaded Temperature-Sensitive Hydrogel as Biomimetic Mucus Attenuated Murine Ulcerative Colitis via Repairing the Mucosal Barriers

The pathogenesis of ulcerative colitis (UC) is associated with the shedding of the gut mucus. Herein, inspired by the biological functions of mucus, growth factors-loaded in situ hydrogel (PHE-EK) was designed for UC treatment by integrating dihydrocaffeic acid-modified poloxamer as a thermosensitive material with hyaluronic acid (colitis-specific adhesive), epigallocatechin-3-gallate (antibacterial agent), and bioactive factors (KPV tripeptide and epidermal growth factor). PHE-EK presented good thermosensitive properties, as a flowable liquid at room temperature and gelled within 10 s when exposed to body temperature. PHE-EK hydrogel presented good mechanical strength with a strain of 77.8%. Moreover, PHE-EK hydrogel displayed antibacterial activity against Escherichia coli. Importantly, in vitro and in vivo adhesive tests showed that the PHE-EK hydrogel could specifically adhere to the inflamed colon via electrostatic interaction. When PHE-EK as a biomimetic mucus was rectally administrated to colitis rats, it effectively hindered the body weight loss, reduced the disease activity index and improved the colonic shorting. Moreover, the expression of pro-inflammatory cytokines (e.g., IL-1β, IL-6, and TNF-α) at the laminae propria or epitheliums of the colon for colitis rats was substantially inhibited by PHE-EK. Besides, the colonic epitheliums were well rearranged, and the tight junction proteins (Zonula-1 and Claudin-5) between them were greatly upregulated after PHE-EK treatment. Collectively, PHE-EK might be a promising therapy for UC.

TL1A promotes metastasis and EMT process of colorectal cancer

Background

Metastasis is the major problem of colorectal cancer (CRC) and is correlated with the high mortality. Tumor necrosis factor-like cytokine 1A (TL1A) is a novel regulatory factor for inflammatory diseases. This work aimed to investigate the role of TL1A in CRC metastasis.

Method

AOM/DSS-induced mouse model, xenograft tumor model and metastasis murine model were established to mimic the colitis-associated CRC and investigate CRC growth and metastasis in vivo. Colon tissues were assessed by hematoxylin/eosin (HE) staining and immunohistochemistry (IHC). CRC cell metastasis in vivo was observed using in vivo imaging system (IVIS). Cell viability and proliferation were examined using cell counting kit 8 (CCK-8) and EdU experiments. The expression of tumor growth factor β (TGFβ) and metastatic biomarkers were detected using western blotting experiment. The in vitro cell metastasis was measured by Transwell.

Results

Knockdown of TL1A notably suppressed the generation of colonic tumors in azoxymethane/dextran sodium sulfate (AOM/DSS) model, suppressed in vivo CRC cell growth, as well as lung and liver metastasis. The inflammation response and inflammatory cell infiltration in tumor sites were decreased by TL1A depletion. The in vitro CRC cell growth and metastasis was also suppressed by shTL1A, along with altered expression of epithelial mesenchymal transition (EMT) biomarkers. TL1A depletion suppressed the level of the TGF-β1 receptor (TβRI) and phosphorylation of Smad3 in CRC cells. Stimulation with TGF-β recovered the CRC cell migration and invasion that suppressed by shTL1A.

Conclusion

Our work implicated TL1A as a promoter of CRC generation and metastasis and defines TGF-β/Smad3 signaling as mediator of TL1A-regualated CRC cell metastasis.

Investigational drugs for the treatment of scleroderma: what's new?

INTRODUCTION

Systemic sclerosis (SSc) is an orphan, chronic, autoimmune, fibrotic disease with unknown etiology characterized by progressive fibrosis of the skin and internal organs. SSc has the highest mortality, the deadliest among the connective tissue diseases, despite the introduction of new treatment options in the past decades.

AREAS COVERED

The aim of the current systematic review was to investigate new targeted therapy and their impact on disease progression, mainly focusing on phase I and II clinical trials within the past three years.

EXPERT OPINION

Despite recent groundbreaking advancements in understanding SSc pathophysiology, early diagnosis and early introduction of effective targeted treatments within the optimal window of opportunity to prevent irreversible disease damage still represents a significant clinical challenge. Ongoing significant research for new molecular and epigenetics pathways is of fundamental importance to offer new perspectives on disease phenotype and for the development of personalized treatment strategies.

Biomarker-responsive engineered probiotic diagnoses, records, and ameliorates inflammatory bowel disease in mice

Rapid advances in synthetic biology have fueled interest in engineered microorganisms that can diagnose and treat disease. However, designing bacteria that detect dynamic disease-associated biomarkers that then drive treatment remains difficult. Here, we have developed an engineered probiotic that noninvasively monitors and records inflammatory bowel disease (IBD) occurrence and progression in real time and can release treatments via a self-tunable mechanism in response to these biomarkers. These intelligent responsive bacteria for diagnosis and therapy (i-ROBOT) consists of E. coli Nissle 1917 that responds to levels of the inflammatory marker thiosulfate by activating a base-editing system to generate a heritable genomic DNA sequence as well as producing a colorimetric signal. Fluctuations in thiosulfate also drive the tunable release of the immunomodulator AvCystatin. Orally administering i-ROBOT to mice with colitis generated molecular recording signals in processed fecal and colon samples and effectively ameliorated disease. i-ROBOT provides a promising paradigm for gastrointestinal and other metabolic disorders.

Macrophages-microenvironment crosstalk in fibrostenotic inflammatory bowel disease: from basic mechanisms to clinical applications

INTRODUCTION

Intestinal fibrosis is a common complication of Inflammatory Bowel Disease (IBD) with no available drugs. The current therapeutic principle is surgical intervention as the core. Intestinal macrophages contribute to both the progression of inflammation and fibrosis. Understanding the role of macrophages in the intestinal microenvironment could bring new hope for fibrosis prevention or even reversal.

AREAS COVERED

This article reviewed the most relevant reports on macrophage in the field of intestinal fibrosis. The authors discussed current opinions about how intestinal macrophages function and interact with surrounding mediators during inflammation resolution and fibrostenotic IBD. Based on biological mechanisms findings, authors summarized related clinical trial outcomes.

EXPERT OPINION

The plasticity of intestinal macrophages allows them to undergo dramatic alterations in their phenotypes or functions when exposed to gastrointestinal environmental stimuli. They exhibit distinct metabolic characteristics, secrete various cytokines, express unique surface markers, and transmit different signals. Nevertheless, the specific mechanism through which the intestinal macrophages contribute to intestinal fibrosis remains unclear. It should further elucidate a novel therapeutic approach by targeting macrophages, especially distinct mechanisms in specific subgroups of macrophages involved in the progression of fibrogenesis in IBD.

Emerging Role of Dendritic Cell Intervention in the Treatment of Inflammatory Bowel Disease

Dendritic cells (DCs) are the most important antigen-presenting cells and are pivotal in initiating effective adaptive immune responses to induce immune tolerance and maintain immune homeostasis. Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, is chronic, intestinal inflammatory and autoimmune disorder. DCs participate in IBD pathogenesis. This review is aimed at briefly discussing the role of DCs in IBD and the relationship between them and highlighting the prominent role of these cells in the treatment of these disorders.

Intestinal Fibrosis in Inflammatory Bowel Disease and the Prospects of Mesenchymal Stem Cell Therapy

Intestinal fibrosis is an important complication of inflammatory bowel disease (IBD). In the course of the development of fibrosis, certain parts of the intestine become narrowed, significantly destroying the structure and function of the intestine and affecting the quality of life of patients. Chronic inflammation is an important initiating factor of fibrosis. Unfortunately, the existing anti-inflammatory drugs cannot effectively prevent and alleviate fibrosis, and there is no effective anti-fibrotic drug, which makes surgical treatment the mainstream treatment for intestinal fibrosis and stenosis. Mesenchymal stem cells (MSCs) are capable of tissue regeneration and repair through their self-differentiation, secretion of cytokines, and secretion of extracellular vesicles. MSCs have been shown to play an important therapeutic role in the fibrosis of many organs. However, the role of MSC in intestinal fibrosis largely remained unexplored. This review summarizes the mechanism of intestinal fibrosis, including the role of immune cells, TGF-β, and the gut microbiome and metabolites. Available treatment options for fibrosis, particularly, MSCs are also discussed.

Antitumor Necrosis Factor-like Ligand 1A Therapy Targets Tissue Inflammation and Fibrosis Pathways and Reduces Gut Pathobionts in Ulcerative Colitis

BACKGROUND

The first-in-class treatment PF-06480605 targets the tumor necrosis factor-like ligand 1A (TL1A) molecule in humans. Results from the phase 2a TUSCANY trial highlighted the safety and efficacy of PF-06480605 in ulcerative colitis. Preclinical and in vitro models have identified a role for TL1A in both innate and adaptive immune responses, but the mechanisms underlying the efficacy of anti-TL1A treatment in inflammatory bowel disease (IBD) are not known.

METHODS

Here, we provide analysis of tissue transcriptomic, peripheral blood proteomic, and fecal metagenomic data from the recently completed phase 2a TUSCANY trial and demonstrate endoscopic improvement post-treatment with PF-06480605 in participants with ulcerative colitis.

RESULTS

Our results revealed robust TL1A target engagement in colonic tissue and a distinct colonic transcriptional response reflecting a reduction in inflammatory T helper 17 cell, macrophage, and fibrosis pathways in patients with endoscopic improvement. Proteomic analysis of peripheral blood revealed a corresponding decrease in inflammatory T-cell cytokines. Finally, microbiome analysis showed significant changes in IBD-associated pathobionts, Streptococcus salivarius, S. parasanguinis, and Haemophilus parainfluenzae post-therapy.

CONCLUSIONS

The ability of PF-06480605 to engage and inhibit colonic TL1A, targeting inflammatory T cell and fibrosis pathways, provides the first-in-human mechanistic data to guide anti-TL1A therapy for the treatment of IBD.

Immunological Regulation of Intestinal Fibrosis in Inflammatory Bowel Disease

Intestinal fibrosis is a late-stage phenotype of inflammatory bowel disease (IBD), which underlies most of the long-term complications and surgical interventions in patients, particularly those with Crohn's disease. Despite these issues, antifibrotic therapies are still scarce, mainly due to the current lack of understanding concerning the pathogenetic mechanisms that mediate fibrogenesis in patients with chronic intestinal inflammation. In the current review, we summarize recent evidence regarding the cellular and molecular factors of innate and adaptive immunity that are considered critical for the initiation and amplification of extracellular matrix deposition and stricture formation. We focus on the role of cytokines by dissecting the pro- vs antifibrotic components of the immune response, while taking into consideration their temporal association to the progressive stages of the natural history of IBD. We critically present evidence from animal models of intestinal fibrosis and analyze inflammation-fibrosis interactions that occur under such experimental scenarios. In addition, we comment on recent findings from large-scale, single-cell profiling of fibrosis-relevant populations in IBD patients. Based on such evidence, we propose future potential targets for antifibrotic therapies to treat patients with IBD.

Herb-Partitioned Moxibustion Improves Crohn's Disease-Associated Intestinal Fibrosis by Suppressing the RhoA/ROCK1/MLC Pathway

Background and Aims

Intestinal fibrosis is one of the severe and common complications of Crohn's disease (CD), but the etiology and pathogenesis remain uncertain. The study intended to examine whether the effect of herb-partitioned moxibustion on rats with CD-associated intestinal fibrosis is associated with the RhoA/ROCK1/MLC pathway.

Methods

All experimental rats were randomly allocated into the normal control group (NC), model control group (MC), and herb-partitioned moxibustion group (HPM). Intestinal fibrosis was established in rats with CD by repeated rectal administrations of 2,4,6-trinitrobenzenesulfonic acid (TNBS). Herb-partitioned moxibustion was applied at the Qihai (CV6) and Tianshu (ST25) acupoints once daily for 10 days in the HPM group. In this study, histological changes were examined by hematoxylin and eosin (HE) staining; then, Masson's trichrome staining was used to assess the degree of fibrosis in each group. Experimental methods of immunohistochemistry, western blotting, and real-time PCR were applied to detect the levels of α-SMA, collagen III, RhoA, ROCK1, and p-MLC. Moreover, the double immunofluorescent staining for the colocalization of both α-SMA and ROCK1 was performed.

Results

Contrasted with the normal controls, the collagen deposition and fibrosis scores were increased in colonic tissue of model rats, and HPM decreased the collagen deposition and fibrosis scores. The protein of α-SMA and collagen III in the MC group exceeds that of the NC group; HPM decreased the expression of α-SMA and collagen III in rats with intestinal fibrosis. Similarly, the expression of RhoA, ROCK1, and p-MLC in model rats was obviously increased compared with normal controls; the expression of RhoA, ROCK1, and p-MLC was decreased after HPM. The coexpression of α-SMA and ROCK1 in rats with intestinal fibrosis was higher than normal rats.

Conclusion

HPM improves CD-associated intestinal fibrosis by suppressing the RhoA/ROCK1/MLC pathway.

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.

Effect and Mechanism of TL1A Expression on Epithelial-Mesenchymal Transition during Chronic Colitis-Related Intestinal Fibrosis

BACKGROUND AND AIMS

Recent evidences reveal that epithelial to mesenchymal transition (EMT) exacerbates the process of intestinal fibrosis. Tumor necrosis factor-like ligand 1A (TL1A) is a member of the tumor necrosis family (TNF), which can take part in the development of colonic inflammation and fibrosis by regulating immune response or inflammatory factors. The purpose of this study was to elucidate the possible contribution of TL1A in onset and progression of intestinal inflammation and fibrosis through EMT.

METHODS

Colonic specimens were obtained from patients with inflammatory bowel disease (IBD) and control individuals. The expression levels of TL1A and EMT-related markers in intestinal tissues were evaluated. Furthermore, the human colorectal adenocarcinoma cell line, HT-29, was stimulated with TL1A, anti-TL1A antibody, or BMP-7 to assess EMT process. In addition, transgenic mice expressing high levels of TL1A in lymphoid cells were used to further investigate the mechanism of TL1A in intestinal fibrosis.

RESULTS

High levels of TL1A expression were detected in the intestinal specimens of patients with ulcerative colitis and Crohn's disease and were negatively associated with the expression of an epithelial marker (E-cadherin), while it was positively associated with the expression of interstitial markers (FSP1 and α-SMA). Transgenic mice with high expression of TL1A were more sensitive to dextran sodium sulfate and exhibited severe intestinal inflammation and fibrosis. Additionally, the TGF-β1/Smad3 pathway may be involved in TL1A-induced EMT, and the expression of IL-13 and EMT-related transcriptional molecules (e.g., ZEB1 and Snail1) was increased in the intestinal specimens of the transgenic mice. Furthermore, TL1A-induced EMT can be influenced by anti-TL1A antibody or BMP-7 in vitro.

CONCLUSIONS

TL1A participates in the formation and process of EMT in intestinal fibrosis. This new knowledge enables us to better understand the pathogenesis of intestinal fibrosis and identify new therapeutic targets for its treatment.

Novel mechanisms and clinical trial endpoints in intestinal fibrosis

The incidence of inflammatory bowel diseases (IBD) worldwide has resulted in a global public health challenge. Intestinal fibrosis leading to stricture formation and bowel obstruction is a frequent complication in Crohn's disease (CD), and the lack of anti-fibrotic therapies makes elucidation of fibrosis mechanisms a priority. Progress has shown that mesenchymal cells, cytokines, microbial products, and mesenteric adipocytes are jointly implicated in the pathogenesis of intestinal fibrosis. This recent information puts prevention or reversal of intestinal strictures within reach through innovative therapies validated by reliable clinical trial endpoints. Here, we review the role of immune and non-immune components of the pathogenesis of intestinal fibrosis, including new cell clusters, cytokine networks, host-microbiome interactions, creeping fat, and their translation for endpoint development in anti-fibrotic clinical trials.

Analysis of therapeutic potential of preclinical models based on DR3/TL1A pathway modulation (Review)

Death receptor 3 (DR3) and its corresponding ligand, tumor necrosis factor-like ligand 1A (TL1A), belong to the tumor necrosis factor superfamily. Signaling via this receptor-ligand pair results in pro-inflammatory and anti-inflammatory effects. Effector lymphocytes can be activated to exert pro-inflammatory activity by triggering the DR3/TL1A pathway. By contrast, DR3/TL1A signaling also induces expansion of the suppressive function of regulatory T cells, which serve an important role in exerting anti-inflammatory functions and maintaining immune homeostasis. Preclinical evidence indicates that neutralizing and agonistic antibodies, as well as ligand-based approaches targeting the DR3/TL1A pathway, may be used to treat diseases, including inflammatory and immune-mediated diseases. Accumulating evidence has suggested that modulating the DR3/TL1A pathway is a promising therapeutic approach for patients with these diseases. This review discusses preclinical models to gauge the progress of therapeutic strategies for diseases involving the DR3/TL1A pathway to aid in drug development.

TL1A: A New Potential Target in the Treatment of Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), are chronic inflammatory diseases of the gastrointestinal tract. In the last few years, the development of biological agents targeting cytokines and receptors involved in IBD pathogenesis has led to better outcomes and has improved the course of the disease. Despite their effectiveness, drugs such as tumor necrosis factor (TNF) inhibitors, anti-Interleukin-12/23 and anti-integrins, do not induce a response in about one-third of patients, and 40% of patients lose response over time. Therefore, more efficient therapies are required. Recent studies showed that TL1A (Tumor necrosis factor-like cytokine 1A) acts as a regulator of mucosal immunity and participates in immunological pathways involved in the IBD pathogenesis. In this review article, we analyze the role of TL1A as a new potential target therapy in IBD patients.

TL1A (TNFSF15) genotype affects the long-term therapeutic outcomes of anti-TNFα antibodies for Crohn's disease patients

Background and Aim

TL1A (TNFSF15) is a major Crohn's disease (CD) susceptibility gene, especially in the East Asian population, and is also known to be associated with some clinical phenotypes, such as stricturing and penetrating behavior. This study aims to investigate the association between TL1A genotype and the long‐term therapeutic outcomes of infliximab and adalimumab in Japanese CD patients.

Methods

We investigated 119 biologic‐naïve CD patients treated with infliximab or adalimumab. TL1A ‐358C/T (rs6478109) was genotyped as a tag single nucleotide polymorphism (SNP) for CD risk or nonrisk haplotype of TL1A (the ‐358C allele is a risk allele for CD development). We compared the long‐term therapeutic outcomes of anti‐tumor necrosis factor (TNF) antibodies between the TL1A ‐358C/C group and the C/T+T/T group.

Results

Sixty‐nine cases (58.0%) were homozygous for the risk allele (TL1A ‐358C/C group), and 50 cases (42.0%) were heterozygous for the risk allele or homozygous for the protective allele (TL1A ‐358C/T+T/T group). No significant differences were found in the cumulative retention rates and the relapse‐free survival between the TL1A genotypes. However, the surgery‐free survival was significantly lower in the TL1A ‐358C/C group than in the C/T+T/T group (log‐rank test, P < 0.05). Multivariate analysis showed that TL1A ‐358C/C was identified as an independent risk factor for surgery (hazard ratio, 4.67; 95% confidence interval, 1.39–22.1; P = 0.025).

Conclusion

An association was found between the TL1A genotype and the therapeutic outcomes of anti‐TNF therapy. Our data indicate that the design of customized therapy with anti‐TNF antibodies using TL1A genomic information could be effective in the future.

Role of Interleukin-17 in Pathogenesis of Intestinal Fibrosis in Mice

BACKGROUND

The level of interleukin (IL)-17 is commonly increased in serum and intestinal mucosa of patients with inflammatory bowel disease, especially Crohn's disease with intestinal stricture. However, the role of IL-17 in the pathogenesis of intestinal fibrosis and the effect of anti-IL-17 treatment on intestinal fibrosis remain unclear; these issues are studied in vivo in this study.

METHOD

A total of 24 wild female Balb/c mice (18-22 g) were randomly divided into three groups: (1) control group, (2) 2,4,6-trinitrobenzenesulfonic acid (TNBS) + immunoglobulin G (IgG) group, and (3) TNBS + anti-IL-17 group. The levels of IL-17, IL-1β, transforming growth factor (TGF)-β1, and tumor necrosis factor (TNF)-α in blood and of collagen 3 and IL-17 in gut were measured by enzyme-linked immunosorbent assay (ELISA). The messenger RNA (mRNA) levels of collagen 3, IL-17, TNF-α, tissue inhibitor of metalloproteinase (TIMP)-1, and matrix metalloproteinase (MMP)-2 in gut were measured by reverse-transcription polymerase chain reaction. The protein expression of IL-17, collagen 3, TNF-α, TIMP-1, and MMP-2 were measured by immunoblot analysis. Collagen deposition was evaluated by standard hematoxylin and eosin and Masson's trichrome staining.

RESULTS

The profibrogenic cytokines IL-17, IL-1β, TGF-β1, and TNF-α in serum, mRNA levels of collagen 3, IL-17, TNF-α, TIMP-1, and MMP-2, and protein levels of IL-17, collagen 3, TNF-α, TIMP-1, and MMP-2 in gut were upregulated in TNBS-induced intestinal fibrosis mice. Treatment with anti-IL-17 antibody significantly alleviated intestinal fibrosis and reduced both mRNA and protein levels of collagen 3, TNF-α, TIMP-1, and MMP-2. The levels of profibrogenic cytokines IL-1β, TGF-β1, and TNF-α were also decreased in mice treated with anti-IL-17 antibody.

CONCLUSIONS

IL-17 contributes to the pathogenesis of intestinal fibrosis, and anti-IL-17 therapy may weaken this effect by downregulating expression of profibrogenic cytokines and disturbing the MMP/TIMPs balance.

Intracoronary and peripheral blood levels of TNF-like Cytokine 1A (TL1A) in patients with acute coronary syndrome

BACKGROUND

TNF-like cytokine 1A (TL1A) is a subgroup of the tumor necrosis factor superfamily that exerts pleiotropic effects on cell proliferation, inflammation, activation, and differentiation of immune cells. The purpose of the current study is to investigate the clinical significance of TL1A expression in coronary and peripheral blood of patients with acute coronary syndrome (ACS) to determine if TL1A levels can serve as an accurate prognostic indicator.

METHODS

A total of 141 patients undergoing coronary angiography were divided into 4 groups: Control (n = 35), Unstable Angina (UA) (n = 35), acute non-ST segment elevation myocardial infarction (NSTEMI) (n = 37), and acute ST segment elevation myocardial infarction (STEMI) (n = 34). The levels of TL1A, MPO, hs-CRP, and IL-10 were detected in coronary and peripheral blood using enzyme linked immunosorbent assay (ELISA), and the MACE incidence rates were compared during 26.3 months of follow-up.

RESULTS

TL1A levels were not significantly different between the UA group and control group. In the UA group, TL1A levels were not significantly different between coronary blood and peripheral blood. However, TL1A levels were higher in the STEMI and NSTEMI groups than in the control group (P < .05). Moreover, TL1A levels in the coronary blood of the STEMI and NSTEMI groups were higher than in the peripheral blood (P < .05). The expression of TL1A in the coronary blood was the highest in the STEMI group. In addition, TL1A level in the coronary blood was highly correlated with levels in the peripheral blood (correlation coefficient: 0.899, P < .001). The hs-CRP and MPO levels in the coronary and peripheral blood of all the UA, NSTEMI, and STEMI groups were higher than the control group. Plasma IL-10 levels in all the UA, NSTEMI and STEMI groups were lower than those in the control group. Plasma TL1A level was positively correlated with the cTnI level, degree of coronary thrombus burden, occurrence of slow coronary flow / no coronary reflow and MACE, but negatively correlated with the IL-10 level or non-correlated with the Syntax score.

CONCLUSION

Plasma TL1A concentration levels can be used as a predictor of inflammatory response and prognosis in patients with ACS.

TRIAL REGISTRATION

ClinicalTrials.gov, number: NCT02430025; Unique Protocol ID: FJPH20150101; Brief Title: Fujian Province Cardiovascular Diseases Study (FJCVD).

Fibrostenotic strictures in Crohn's disease

The use of biologic agents including anti-tumor necrosis factor monoclonal antibodies followed by anti-integrins and anti-interleukins has drastically changed the treatment paradigm of Crohn’s disease (CD) by improving clinical symptoms and mucosal healing. However, up to 70% of CD patients still eventually undergo surgery mainly due to fibrostenotic strictures. There are no specific anti-fibrotic drugs yet. This review comprehensively addresses the mechanism, prediction, diagnosis and treatment of the fibrostenotic strictures in CD. We also introduce promising anti-fibrotic agents which may be available in the near future and summarize challenges in developing novel therapies to treat fibrostenotic strictures in CD.

A Comprehensive Review and Update on the Pathogenesis of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic and life-threating inflammatory disease of gastroenteric tissue characterized by episodes of intestinal inflammation. The pathogenesis of IBD is complex. Recent studies have greatly improved our knowledge of the pathophysiology of IBD, leading to great advances in the treatment as well as diagnosis of IBD. In this review, we have systemically reviewed the pathogenesis of IBD and highlighted recent advances in host genetic factors, gut microbiota, and environmental factors and, especially, in abnormal innate and adaptive immune responses and their interactions, which may hold the keys to identify novel predictive or prognostic biomarkers and develop new therapies.

Candidate single nucleotide polymorphisms of irritable bowel syndrome: a systemic review and meta-analysis

Background

Genetic factors increase the risk of irritable bowel syndrome (IBS). Analysis of single nucleotide polymorphisms (SNPs) has been used in IBS patients, but the findings are inconsistent. The goal of this review was to synthesize all the published SNPs studies of IBS through meta-analysis to objectively evaluate the relevance of SNPs to IBS risks.

Methods

IBS - related polymorphisms studies from 2000 to 2018 were searched. Pooled odds ratios with a 95% confidence interval for each SNP were evaluated through five genetic models. Ethnicity, ROME criteria and IBS subtypes were defined for subgroup analyze.

Results

Ten relevant genes were evaluated. SNPs rs4263839 and rs6478108 of TNFSF15 associated with an increased risk of IBS; IL6 rs1800795 increased the risk for Caucasian IBS patients which diagnosed by Rome III criteria; and IL23R rs11465804 increased the risk for IBS-C patients. IL10 rs1800896 GG genotype associated with a decreased risk of IBS. No evidence supported the association of GNβ3 rs5443, TNFα rs1800629, and IL10 rs1800871 to IBS in this study.

Conclusions

This meta-analysis presents an in-depth overview for IBS SNPs analysis. It was confirmed that polymorphisms of TNFSF15 associated with increased IBS risk, while IL10 rs1800896 associated with decreased IBS risk. It might offer some insights into polymorphisms of inflammation factors which might affect IBS susceptibility. Moreover, the analysis also emphasizes the importance of diagnostic criteria and phenotype homogeneity in IBS genetic studies.

Fibrogenesis in Chronic DSS Colitis is Not Influenced by Neutralisation of Regulatory T Cells, of Major T Helper Cytokines or Absence of IL-13

Mechanisms underlying fibrogenesis in chronic colitis are largely unknown. There is an urgent need for clinical markers and identification of targets to prevent, treat and limit intestinal fibrosis. This study investigated the contribution of major T cell cytokines and T regulatory cells (Tregs) to inflammation and fibrosis induced in a model of experimental colitis by oral intake of dextran sodium sulphate (DSS) in wild type and IL-13 knock-out C57Bl/6 mice. Inflammation and fibrosis were scored by macroscopic and histological examination and fibrosis was quantified by hydroxyproline. Numbers of Tregs and IFN-γ⁺, IL-13⁺ and IL-17A⁺ CD4⁺ T helper (Th) cells in mesenteric lymph nodes increased during chronic DSS administration and mRNA for IFN-γ and IL-17 in the inflamed colon tissue was upregulated. However, antibody-mediated neutralisation of IFN-γ or IL-17A/F in a therapeutic setting had no effect on chronic intestinal inflammation and fibrosis. Antibody-mediated depletion of Tregs did not enhance fibrosis, nor did IL-13 deficiency have an effect on the fibrotic disease. These data argue against an important contribution of Tregs and of the cytokines IFN-γ, IL-13, IL-17A, IL-17F in the induction and/or control of fibrosis in this Crohn's disease like murine model.

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.