Immune cell trafficking and retention in inflammatory bowel disease: mechanistic insights and therapeutic advances

Bacillus clausii spores maintain gut homeostasis in murine ulcerative colitis via modulating microbiota, apoptosis, and the TXNIP/NLRP3 inflammasome cascade

Ulcerative colitis (UC), a persistent immune-mediated disorder lacking effective treatment, is distinguished by gut microbiota dysbiosis, abnormal activation of the NLRP3 inflammasome pathway, and apoptosis. Despite growing attention to these factors, understanding their significance in UC pathogenesis remains a challenge. The present study explores the potential therapeutic impact of Bacillus clausii (Bc) spores in a murine UC model induced by drinking 4 % (w/v) dextran sulfate sodium (DSS) in C57BL/6 mice. Subsequently, the DSS-induced mice were orally administered either Bc at varying concentrations (105 and 1010 Colony forming unit, CFU) or sulfasalazine (SSZ) at a dosage of 200 mg/kg for 7 days. The disease-specific activity index (DAI) was calculated daily utilizing parameters such as body weight, diarrhea, and bloody stool. Changes in fecal Firmicutes and Bacteroidetes abundance, colonic TXNIP and NLRP3 contents, as well as colonic caspase-1, IL-1β, Bax, and Bcl-2 expression, were investigated. Additionally, markers related to oxidative stress and inflammation, histopathological changes and caspase-3 immunohistochemistry testing were conducted. DSS-treated mice had significantly higher DAI scores compared to controls, indicating severe colitis. However, SSZ treatment or Bc (105 CFU) dramatically lowered DAI scores, with the highest Bc dosage (1010 CFU) producing the greatest improvement. Furthermore, Bc (1010 CFU) substantially (p < 0.05) boosted fecal Firmicutes while decreased Bacteroidetes, indicating reversal of gut dysbiosis. Bc effectively reduced colonic oxidative stress and inflammation by replenishing GSH and catalase and modulating the NF-κB, Nrf2/HO-1, and TXNIP/NLRP3 pathways. Additionally, Bc (1010 CFU) exhibited histologically almost normal mucosa, with maintained architecture and reduced apoptosis, as seen by normalization of Bcl2 and Bax with decreased caspase-3. Collectively, these findings point to the potential usefulness of Bc spores in preventing and treating DSS-induced colitis, positioning them as a promising candidate for UC management.

VCAM-1 as a common biomarker in inflammatory bowel disease and colorectal cancer: unveiling the dual anti-inflammatory and anti-cancer capacities of anti-VCAM-1 therapies

Vascular cell adhesion molecule (VCAM)-1 has garnered significant research attention due to its potential as a disease biomarker and drug target across several inflammatory pathologies-including atherosclerosis, asthma, rheumatoid arthritis, and inflammatory bowel disease (IBD). The VCAM-1 protein has also been noted for its functional involvement in cancer metastasis and drug resistance to conventional chemotherapeutics. Although the anti-inflammatory and anti-cancer facets of VCAM-1 antagonisation have been examined separately, there is yet to be a review that explicitly addresses the functional interrelationship between these mechanisms. Furthermore, the pleiotropic mechanisms of anti-VCAM-1 therapies may present a useful paradigm for designing drug candidates with synergistic anti-inflammatory and anti-tumorigenic effects. The pathological overlap between inflammatory bowel disease (IBD) and colitis-associated colorectal cancer (CRC) serves as the quintessential disease model to observe this therapeutic duality. This review thereby details the adhesive mechanisms of VCAM-1 in colorectal disease-specifically, driving immune cell infiltration during IBD and tumour cell metastasis in CRC-and posits the potential of this receptor as a common drug target for both diseases. To explore this hypothesis, the current progress of novel VCAM-1-directed drug candidates in experimental models of IBD and CRC is also discussed.

Biological agents as attractive targets for inflammatory bowel disease therapeutics

Inflammatory bowel disease (IBD) refers to a group of chronic, recurrent intestinal inflammatory conditions with a complex cause and unclear underlying mechanisms. It includes two main types: Ulcerative colitis (UC) and Crohn's disease (CD). The conventional treatment of IBD mainly includes 5-aminosalicylates, glucocorticoids, and immunosuppressive drugs, which have their limitations. Recent advancements in IBD research have expanded treatment options, with biological agents playing a key role. Anti-tumor necrosis factor alpha has emerged as the first-line therapy for moderate to severe IBD. Anti-integrin antibodies have also become important for the treatment, and vedolizumab is often used in cases of anti-tumor necrosis factor-alpha failure and intolerance to other treatments. Other biological agents are being tested in clinical trials at different stages. This article reviews the efficacy and safety of the primary biological therapies for IBD and provides a comprehensive analysis of the current clinical challenges associated with the disease.

MAIT cell homing in intestinal homeostasis and inflammation

Mucosa-associated invariant T (MAIT) cells are a large population of unconventional T cells widely distributed in the human gastrointestinal tract. Their homing to the gut is central to maintaining mucosal homeostasis and immunity. This review discusses the potential mechanisms that guide MAIT cells to the intestinal mucosa during homeostasis and inflammation, emphasizing the roles of chemokines, chemokine receptors, and tissue adhesion molecules. The potential influence of the gut microbiota on MAIT cell homing to different regions of the human gut is also discussed. Last, we introduce how organoid technology offers a potentially valuable approach to advance our understanding of MAIT cell tissue homing by providing a more physiologically relevant model that mimics the human gut tissue. These models may enable a detailed investigation of the gut-specific homing mechanisms of MAIT cells. By understanding the regulation of MAIT cell homing to the human gut, potential avenues for therapeutic interventions targeting gut inflammatory conditions such as inflammatory bowel diseases (IBD) may emerge.

Multimodal Profiling of Peripheral Blood Identifies Proliferating Circulating Effector CD4+ T Cells as Predictors for Response to Integrin α4β7-Blocking Therapy in Inflammatory Bowel Disease

BACKGROUND & AIMS

Despite the success of biological therapies in treating inflammatory bowel disease, managing patients remains challenging due to the absence of reliable predictors of therapy response.

METHODS

In this study, we prospectively sampled 2 cohorts of patients with inflammatory bowel disease receiving the anti-integrin α4β7 antibody vedolizumab. Samples were subjected to mass cytometry; single-cell RNA sequencing; single-cell B and T cell receptor sequencing (BCR/TCR-seq); serum proteomics; and multiparametric flow cytometry to comprehensively assess vedolizumab-induced immunologic changes in the peripheral blood and their potential associations with treatment response.

RESULTS

Vedolizumab treatment led to substantial alterations in the abundance of circulating immune cell lineages and modified the T-cell receptor diversity of gut-homing CD4+ memory T cells. Through integration of multimodal parameters and machine learning, we identified a significant increase in proliferating CD4+ memory T cells among nonresponders before treatment compared with responders. This predictive T-cell signature demonstrated an activated T-helper 1/T-helper 17 cell phenotype and exhibited elevated levels of integrin α4β1, potentially making these cells less susceptible to direct targeting by vedolizumab.

CONCLUSIONS

These findings provide a reliable predictive classifier with significant implications for personalized inflammatory bowel disease management.

Multi-omics perspective: mechanisms of gastrointestinal injury repair

In this review, we examine the significance of multi-omics technologies in understanding the plethora of intricate processes that activate gastrointestinal (GI) injury repair. Multi-omics, which includes genomics, transcriptomics, proteomics, and metabolomics, allows intricate mapping of cellular responses and molecular pathways involved in GI repair. We highlight the potential of multi-omics to discover previously unknown therapeutic targets or elucidate the molecular basis of the pathogenesis of GI. Furthermore, we explore the possibilities of integrating omics data to improve prediction models, and summarize the state-of-the-art technological developments and persisting obstacles that hinder the translation of multi-omics into clinical practice. Finally, innovative multi-omics approaches that can improve patient outcomes and advance therapeutic strategies in GI medicine are discussed.

Translational characterization of immune pathways in inflammatory bowel disease: insights for targeted treatments

INTRODUCTION

The pathogenesis of inflammatory bowel disease (IBD) involves the dysregulation of multiple inflammatory pathways. The understanding of these mechanisms allows their selective targeting for therapeutic purposes. The discovery of Tumor Necrosis Factor-alpha's (TNF-α) role in mucosal inflammation ushered an exciting new era of drug development which now comprises agents targeting multiple pro-inflammatory signaling pathways, integrins, and leukocyte trafficking regulators.

AREA COVERED

This review provides an overview of the main molecular players of IBD, their translation into therapeutic targets and the successful development of the advanced agents modulating them. We combine basic science with clinical trials data to present a critical review of both the successful and failed drug development programs. A PubMed literature search was conducted to delve into the available literature and clinical trials.

EXPERT OPINION

The treatment landscape for IBD has rapidly expanded, particularly with the development of biologics targeting TNF-α, integrins, and S1P modulators, as well as newer agents such as IL-12/IL-23 inhibitors and JAK inhibitors, offering robust efficacy and safety profiles. However, challenges persist in understanding and effectively treating difficult-to-treat IBD, highlighting the need for continued research to uncover novel therapeutic targets and optimize patient outcomes.

Advancing therapeutic frontiers: a pipeline of novel drugs for luminal and perianal Crohn's disease management

Crohn's disease (CD) is a chronic, complex inflammatory disorder of the gastrointestinal tract that presents significant therapeutic challenges. Despite the availability of a wide range of treatments, many patients experience primary non-response, secondary loss of response, or adverse events, limiting the overall effectiveness of current therapies. Clinical trials often report response rates below 60%, partly due to stringent inclusion criteria. Emerging therapies that target novel pathways offer promise in overcoming these limitations. This review explores the latest investigational drugs in phases I, II, and III clinical trials for treating both luminal and perianal CD. We highlight promising therapies that target known mechanisms, including selective Janus kinase inhibitors, anti-adhesion molecules, tumor necrosis factor inhibitors, and IL-23 selective inhibitors. In addition, we delve into novel therapeutic strategies such as sphingosine-1-phosphate receptor modulators, miR-124 upregulators, anti-fractalkine (CX3CL1), anti-TL1A, peroxisome proliferator-activated receptor gamma agonists, TGFBRI/ALK5 inhibitors, anti-CCR9 agents, and other innovative small molecules, as well as combination therapies. These emerging approaches, by addressing new pathways and mechanisms of action, have the potential to surpass the limitations of existing treatments and significantly improve CD management. However, the path to developing new therapies for inflammatory bowel disease (IBD) is fraught with challenges, including complex trial designs, ethical concerns regarding placebo use, recruitment difficulties, and escalating costs. The landscape of IBD clinical trials is shifting toward greater inclusivity, improved patient diversity, and innovative trial designs, such as adaptive and Bayesian approaches, to address these challenges. By overcoming these obstacles, the drug development pipeline can advance more effective, accessible, and timely treatments for CD.

Revolutionizing IBD research with on-chip models of disease modeling and drug screening

Inflammatory bowel disease (IBD) comprises chronic inflammatory conditions with complex mechanisms and diverse manifestations, posing significant clinical challenges. Traditional animal models and ethical concerns in human studies necessitate innovative approaches. This review provides an overview of human intestinal architecture in health and inflammation, emphasizing the role of microfluidics and on-chip technologies in IBD research. These technologies allow precise manipulation of cellular and microbial interactions in a physiologically relevant context, simulating the intestinal ecosystem microscopically. By integrating cellular components and replicating 3D tissue architecture, they offer promising models for studying host-microbe interactions, wound healing, and therapeutic approaches. Continuous refinement of these technologies promises to advance IBD understanding and therapy development, inspiring further innovation and cross-disciplinary collaboration.

Expression of IL-7RαlowCX3CR1+ CD8+ T Cells and α4β7 Integrin Tagged T Cells Related to Mucosal Immunity in Children with Inflammatory Bowel Disease

Purpose

The study aimed to investigate the recruiting of T lymphocytes including IL-7Rαlow CX3CR1+ effector memory (EM) CD8+ T cells and α4β7 integrin tagged T cells to inflamed intestinal mucosa.

Methods

Whole blood and mucosal tissues of intestine were collected from 40 children with or without inflammatory bowel disease (IBD). T cell surface staining and immunohistochemistry were done with several antibodies in peripheral blood mononuclear cells (PBMCs) and intestinal mucosa, respectively. Serum levels of cytokines were measured by ELISA.

Results

The frequency of IL-7RαlowCX3CR1+ EM CD8+ T cells in the PBMC was significantly higher in the ulcerative colitis group than in the control group (57.9±17.80% vs. 33.9±15.70%, p=0.021). The frequency of integrin α4β7+ CD4+ T cells in the PBMC was significantly lower in the ulcerative colitis group than in the control group (53.2±27.6% vs. 63.9±13.2%, p=0.022). Serum concentration of TNF-α was higher in the Crohn's disease group than in the control group (26.13±5.01 pg/mL vs. 19.65±6.07 pg/mL, p=0.008). Of the three groups, the ulcerative colitis group had the highest frequency of integrin α4β7+ T cells based on immunohistochemistry analyses for intestinal tissues, followed by the Crohn's disease group and the control group (4.63±1.29 cells vs. 2.0±0.57 cells vs. 0.84±0.52 cells, p<0.001).

Conclusion

Trafficking immune cells with effector memory CD8+ T cells clarified by IL-7RαlowCX3CR1+ and integrin α4β7+ CD4+ T cells might be highly associated with the pathogenesis of ulcerative colitis.

Unravelling the Oral-Gut Axis: Interconnection Between Periodontitis and Inflammatory Bowel Disease, Current Challenges, and Future Perspective

As the opposite ends of the orodigestive tract, the oral cavity and the intestine share anatomical, microbial, and immunological ties that have bidirectional health implications. A growing body of evidence suggests an interconnection between oral pathologies and inflammatory bowel disease [IBD], implying a shift from the traditional concept of independent diseases to a complex, reciprocal cycle. This review outlines the evidence supporting an 'oral-gut' axis, marked by a higher prevalence of periodontitis and other oral conditions in IBD patients and vice versa. We present an in-depth examination of the interconnection between oral pathologies and IBD, highlighting the shared microbiological and immunological pathways, and proposing a 'multi-hit' hypothesis in the pathogenesis of periodontitis-mediated intestinal inflammation. Furthermore, the review underscores the critical need for a collaborative approach between dentists and gastroenterologists to provide holistic oral-systemic healthcare.

Blocking GPR15 Counteracts Integrin-dependent T Cell Gut Homing in Vivo

BACKGROUND AND AIMS

The G protein coupled receptor GPR15 is expressed on and functionally important for T cells homing to the large intestine. However, the precise mechanisms by which GPR15 controls gut homing have been unclear. Thus, we aimed to elucidate these mechanisms as well as to explore the potential of targeting GPR15 for interfering with T cell recruitment to the colon in inflammatory bowel disease [IBD].

METHODS

We used dynamic adhesion and transmigration assays, as well as a humanised in vivo model of intestinal cell trafficking, to study GPR15-dependent effects on gut homing. Moreover, we analysed GPR15 and integrin expression in patients with and without IBD, cross-sectionally and longitudinally.

RESULTS

GPR15 controlled T cell adhesion to MAdCAM-1 and VCAM-1 upstream of α4β7 and α4β1 integrin, respectively. Consistently, high co-expression of these integrins with GPR15 was found on T cells from patients with IBD, and GPR15 also promoted T cell recruitment to the colon in humanised mice. Anti-GPR15 antibodies effectively blocked T cell gut homing in vitro and in vivo. In vitro data, as well as observations in a cohort of patients treated with vedolizumab, suggest that this might be more effective than inhibiting α4β7.

CONCLUSIONS

GPR15 seems to have a broad, but organ-selective, impact on T cell trafficking and is therefore a promising target for future therapy of IBD. Further studies are needed.

3,5-Dimethyl-8-methoxy-3,4-dihydro-1H-isochromen-6-ol Attenuates Ulcerative Colitis via Targeting NLRP3 in Mice

3,5-Dimethyl-8-methoxy-3,4-dihydro-1H-isochromen-6-ol (DMD) is a polyketide compound obtained from the endophytic fungus Penicillium sp. HJT-A-10 of Rhodiola tibetica. R. tibetica is a nourishing food and also used in traditional Chinese medicine and Xizang medicine. In dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mice, DMD significantly alleviated the pathological symptom of UC. Network pharmacology studies have shown that nucleotide-binding domain-like receptor family pyrin domain containing (NLRP) 3 is the primary target protein of DMD associated with anti-UC. In molecular biology studies, DMD suppressed the activation of NLRP3 and decreased the expression of downstream inflammatory proteins and pro-inflammatory cytokines in UC. The finding was further verified in knockout mice. DMD lost the effect of attenuating DSS-induced UC in NLRP3-/- mice. In conclusion, this study demonstrates that DMD reduces inflammatory response and balances the barrier integrity to attenuate UC via targeting NLRP3, and DMD is a potential natural agent or dietary supplement for attenuating UC.

Gingerenone A Attenuates Ulcerative Colitis via Targeting IL-17RA to Inhibit Inflammation and Restore Intestinal Barrier Function

Ulcerative colitis (UC) is a complicated and recurrent intestinal disease. Currently available drugs for UC treatment are scarce, therefore, novel therapeutic drugs for the UC are urgently to be developed. Gingerenone A (GA) is a phenolic compound known for its anti-inflammatory effect, but its effect on UC remains unknown. Here, it is shown that GA protects mice against UC, which is closely associated with inhibiting intestinal mucosal inflammation and enhancing intestinal barrier integrity in vivo and in vitro. Of note, RNA sequencing analysis demonstrates an evident correlation with IL-17 signaling pathway after GA treatment, and this effect is further corroborated by Western blot. Mechanistically, GA directly interacts with IL-17RA protein through pull-down, surface plasmon resonance analysis and molecular dynamics simulation. Importantly, lentivirus-mediated IL-17RA/Act1 knock-down or GA co-treatment with brodalumab/ixekizumab significantly impairs the protective effects of GA against DSS-induced inflammation and barrier dysfunction, suggesting a critical role of IL-17RA signaling for GA-mediated protection against UC. Overall, these results indicate that GA is an effective agent against UC mainly through the direct binding of IL-17RA to inhibit inflammatory signaling activation.

Gut-tropic T cells and extra-intestinal autoimmune diseases

Gut-tropic T cells primarily originate from gut-associated lymphoid tissue (GALT), and gut-tropic integrins mediate the trafficking of the T cells to the gastrointestinal tract, where their interplay with local hormones dictates the residence of the immune cells in both normal and compromised gastrointestinal tissues. Targeting gut-tropic integrins is an effective therapy for inflammatory bowel disease (IBD). Gut-tropic T cells are further capable of entering the peripheral circulatory system and relocating to multiple organs. There is mounting evidence indicating a correlation between gut-tropic T cells and extra-intestinal autoimmune disorders. This review aims to systematically discuss the origin, migration, and residence of gut-tropic T cells and their association with extra-intestinal autoimmune-related diseases. These discoveries are expected to offer new understandings into the development of a range of autoimmune disorders, as well as innovative approaches for preventing and treating the diseases.

Intestinal MAdCAM-1 imaging as biomarker for prognostic in murine models of multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system. Recent evidence suggests that lymphocyte trafficking in the intestines could play a key role in its etiology. Nevertheless, it is not clear how intestinal tissue is involved in the disease onset nor its evolution. In the present study, we aimed to evaluate intestinal inflammation dynamic throughout the disease course and its potential impact on disease progression.

METHODS

We used tissue immunophenotyping (immunohistofluorescence and flow cytometry) and a recently described molecular magnetic resonance imaging (MRI) method targeting mucosal addressin cell adhesion molecule-1 (MAdCAM-1) to assess intestinal inflammation in vivo in two distinct animal models of MS (Experimental Autoimmune Encephalomyelitis - EAE) at several time points of disease progression.

RESULTS

We report a positive correlation between disease severity and MAdCAM-1 MRI signal in two EAE models. Moreover, high MAdCAM-1 MRI signal during the asymptomatic phase is associated with a delayed disease onset in progressive EAE and to a lower risk of conversion to a secondary-progressive form in relapsing-remitting EAE. During disease evolution, in line with a bi-directional immune communication between the gut and the central nervous system, we observed a decrease in T-CD4+ and B lymphocytes in the ileum concomitantly with their increase in the spinal cord.

CONCLUSION

Altogether, these data unveil a crosstalk between intestinal and central inflammation in EAE and support the use of molecular MRI of intestinal MAdCAM-1 as a new biomarker for prognostic in MS patients.

Mucosal α4β7+ Lymphocytes and MAdCAM+ Venules Predict Response to Vedolizumab in Ulcerative Colitis

BACKGROUND

Therapeutic strategies for patients with ulcerative colitis (UC) are based on patient- and disease-related factors in combination with drug characteristics but fail to predict success in individual patients. A considerable proportion of UC patients do not respond to the biological vedolizumab. Therefore, pretreatment biomarkers for therapeutic efficacy are urgently needed. Mucosal markers related to the integrin-dependent T lymphocyte homing could be potent predictors.

METHODS

We prospectively included 21 biological- and steroid-naive UC patients with moderate-to-severe disease activity planned to escalate therapy to vedolizumab. At week 0, before initiating treatment, colonic biopsy specimens were obtained for immunophenotyping and immunohistochemistry. Clinical and endoscopic disease activity were determined at week 16 after 4 infusions of vedolizumab. In addition, we retrospectively included 5 UC patients who were first treated with anti-tumor necrosis factor α before receiving vedolizumab to compare with biological-naive patients.

RESULTS

Abundance of α4β7 on more than 8% of all CD3+ T lymphocytes in colonic biopsies at baseline was predictive for responsiveness to vedolizumab (sensitivity 100%, specificity 100%). The threshold for the proportion of MAdCAM-1+ and PNAd+ of all venules in the biopsies predictive for responsiveness to vedolizumab was ≥2.59% (sensitivity 89%, specificity 100%) and ≥2.41% (sensitivity 61%, specificity 50%), respectively. At week 16, a significant decrease of α4β7+CD3+T lymphocytes was demonstrated in responders (18% [12%-24%] to 8% [3%-9%]; P = .002), while no difference was seen in nonresponders (4% [3%-6%] to 3%; P = .59).

CONCLUSIONS

UC responders to vedolizumab have a higher percentage of α4β7+CD3+ T lymphocytes and a higher proportion of MAdCAM-1+ venules in colonic biopsies than nonresponders before initiating therapy. Both analyses could be promising predictive biomarkers for therapeutic response and may lead to more patient tailored treatment in the future.

Integrated analyses reveal the diagnostic and predictive values of COL5A2 and association with immune environment in Crohn's disease

The pathogenesis of Crohn's disease (CD) involves abnormal immune cell infiltration and dysregulated immune response. Therefore, thorough research on immune cell abnormalities in CD is crucial for improved treatment of this disease. Single-cell RNA sequencing (scRNA-seq) and bulk RNA-seq data of CD were obtained from the Gene Expression Omnibus (GEO) database. Cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT), weighted gene co-expression network analysis (WGCNA), protein-protein interaction (PPI) networks evaluated the proportion of immune infiltrating cells, constructed co-expression network and identified key genes, respectively. Based on the dataset (GSE134809), 15 cell clusters were defined and labeled as different cell types. Among the 11 modules, the yellow module had the closest relationship with plasma cells (cluster 5). Confirmed using RNA sequencing and IHC assay, the expression of COL5A2 in CD samples was higher than that in control samples. Furthermore, the COL5A2 protein expression remarkably decreased in the group of patients who responded to anti-tumor necrosis factor (TNF) treatments, compared to the non-response group. The comprehensive analyses described here provided novel insight into the landscape of CD-associated immune environment. In addition, COL5A2 were identified as potential diagnostic indicators for CD, as well as promising predictive markers for CD patients.

Single Cell Analysis of Human Colonoids Exposed to Uranium-Bearing Dust

BACKGROUND

Uranium exposure remains an important environmental legacy and physiological health concern, with hundreds of abandoned uranium mines located in the Southwestern United States largely impacting underserved indigenous communities. The negative effects of heavy metals on barrier permeability and inhibition of intestinal epithelial healing have been described; however, transcriptomic changes within the intestinal epithelial cells and impacts on lineage differentiation are largely unknown.

OBJECTIVES

Herein, we sought to determine the molecular and cellular changes that occur in the colon in response to uranium bearing dust (UBD) exposure.

METHODS

Human colonoids from three biologically distinct donors were acutely exposed to UBD then digested for single cell RNA sequencing to define the molecular changes that occur to specific identities of colonic epithelial cells. Validation in colonoids was assessed using morphological and imaging techniques.

RESULTS

Human colonoids acutely exposed to UBD exhibited disrupted proliferation and hyperplastic differentiation of the secretory lineage cell, enteroendocrine cells (EEC). Single-cell RNA sequencing also showed more EEC subtypes present in UBD-exposed colonoids.

DISCUSSION

These findings highlight the significance of crypt-based proliferative cells and secretory cell differentiation using human colonoids to model major colonic responses to uranium-bearing particulate dust exposure. https://doi.org/10.1289/EHP13855.

Intestinal Mucosal Immune Barrier: A Powerful Firewall Against Severe Acute Pancreatitis-Associated Acute Lung Injury via the Gut-Lung Axis

The pathogenesis of severe acute pancreatitis-associated acute lung injury (SAP-ALI), which is the leading cause of mortality among hospitalized patients in the intensive care unit, remains incompletely elucidated. The intestinal mucosal immune barrier is a crucial component of the intestinal epithelial barrier, and its aberrant activation contributes to the induction of sustained pro-inflammatory immune responses, paradoxical intercellular communication, and bacterial translocation. In this review, we firstly provide a comprehensive overview of the composition of the intestinal mucosal immune barrier and its pivotal roles in the pathogenesis of SAP-ALI. Secondly, the mechanisms of its crosstalk with gut microbiota, which is called gut-lung axis, and its effect on SAP-ALI were summarized. Finally, a number of drugs that could enhance the intestinal mucosal immune barrier and exhibit potential anti-SAP-ALI activities were presented, including probiotics, glutamine, enteral nutrition, and traditional Chinese medicine (TCM). The aim is to offer a theoretical framework based on the perspective of the intestinal mucosal immune barrier to protect against SAP-ALI.

DHX9 maintains epithelial homeostasis by restraining R-loop-mediated genomic instability in intestinal stem cells

Epithelial barrier dysfunction and crypt destruction are hallmarks of inflammatory bowel disease (IBD). Intestinal stem cells (ISCs) residing in the crypts play a crucial role in the continuous self-renewal and rapid recovery of intestinal epithelial cells (IECs). However, how ISCs are dysregulated in IBD remains poorly understood. Here, we observe reduced DHX9 protein levels in IBD patients, and mice with conditional DHX9 depletion in the intestinal epithelium (Dhx9ΔIEC) exhibit an increased susceptibility to experimental colitis. Notably, Dhx9ΔIEC mice display a significant reduction in the numbers of ISCs and Paneth cells. Further investigation using ISC-specific or Paneth cell-specific Dhx9-deficient mice demonstrates the involvement of ISC-expressed DHX9 in maintaining epithelial homeostasis. Mechanistically, DHX9 deficiency leads to abnormal R-loop accumulation, resulting in genomic instability and the cGAS-STING-mediated inflammatory response, which together impair ISC function and contribute to the pathogenesis of IBD. Collectively, our findings highlight R-loop-mediated genomic instability in ISCs as a risk factor in IBD.

Investigation of the material basis and mechanism of Lizhong decoction in ameliorating ulcerative colitis based on spectrum-effect relationship and network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Lizhong decoction (LZD), a classical herbal prescription recorded by Zhang Zhongjing in Treatise on Febrile and Miscellaneous Diseases, has been extensively used to treat ulcerative colitis (UC) in clinical practice for thousands of years. However, its material basis and underlying mechanism are not yet clear.

AIM OF THE STUDY

This study aims to explore the material basis and potential mechanism of LZD against UC based on the spectrum-effect relationship and network pharmacology.

MATERIALS AND METHODS

First, LZD was extracted by a systematic solvent extraction method into four parts. Ultra-high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) technique was used to identify the compounds from different polar parts, and dextran sulfate sodium (DSS)-induced colitis model was used to evaluate the efficacy of each fraction. Then, the spectrum-effect analyses of compounds and efficacy indicators were established via grey relational analysis (GRA), bivariate correlation analysis (BCA) and partial least squares regression (PLSR). Finally, the potential mechanism of LZD for UC therapy was explored by network pharmacology, and the results were further verified by molecular docking and reverse transcription quantitative polymerase chain reaction (RT-qPCR).

RESULTS

66 chemical components of LZD were identified by UPLC-Q-TOF-MS/MS technology. The pharmacodynamic results showed that extraction parts of LZD had different therapeutic effects on UC, among which ethyl acetate and n-butanol extracts had significant anti-colitis effects, which might be the main effective fractions of LZD. Furthermore, the spectrum-effect analyses indicated that 21 active ingredients such as liquiritin apioside, neolicuroside, formononetin, ginsenoside Rg1, 6-gingesulfonic acid, licoricesaponin A3, liquiritin, glycyrrhizic acid were the main material basis for LZD improving UC. Based on the above results, network pharmacology suggested that the amelioration of LZD on UC might be closely related to the PI3K-Akt signaling pathway. Additionally, molecular docking technology and RT-qPCR further verified that LZD could markedly inhibit the PI3K-Akt signaling pathway.

CONCLUSION

Overall, our study first identified the chemical compositions of LZD by using UPLC-Q-TOF-MS/MS. Furthermore, the material basis and potential mechanism of LZD in improving UC were comprehensively elucidated via spectrum-effect relationships, network pharmacology, molecular docking and experimental verification. The proposed strategy provided a systematic approach for exploring how herbal medicines worked. More importantly, it laid the solid foundation for further clinical application and rational development of LZD.

Etrolizumab-s fails to control E-Cadherin-dependent co-stimulation of highly activated cytotoxic T cells

Despite promising preclinical and earlier clinical data, a recent phase III trial on the anti-β7 integrin antibody etrolizumab in Crohn's disease (CD) did not reach its primary endpoint. The mechanisms leading to this outcome are not well understood. Here we characterize the β7+ T cell compartment from patients with CD in comparison to cells from individuals without inflammatory bowel disease. By flow cytometric, transcriptomic and functional profiling of circulating T cells, we find that triple-integrin-expressing (α4+β7+β1hi) T cells have the potential to home to the gut despite α4β7 blockade and have a specific cytotoxic signature. A subset of triple-integrin-expressing cells readily acquires αE expression and could be co-stimulated via E-Cadherin-αEβ7 interactions in vitro. Etrolizumab-s fails to block such αEβ7 signalling at high levels of T cell stimulation. Consistently, in CD patients treated with etrolizumab, T cell activation correlates with cytotoxic signatures. Collectively, our findings might add one important piece to the puzzle to explain phase III trial results with etrolizumab, while they also highlight that αEβ7 remains an interesting target for future therapeutic approaches in inflammatory bowel disease.

Targeting T-cell integrins in autoimmune and inflammatory diseases

The recruitment of T cells to tissues and their retention there are essential processes in the pathogenesis of many autoimmune and inflammatory diseases. The mechanisms regulating these processes have become better understood over the past three decades and are now recognized to involve temporally and spatially specific interactions between cell-adhesion molecules. These include integrins, which are heterodimeric molecules that mediate in-to-out and out-to-in signalling in T cells, other leukocytes, and most other cells of the body. Integrin signalling contributes to T-cell circulation through peripheral lymph nodes, immunological synapse stability and function, extravasation at the sites of inflammation, and T-cell retention at these sites. Greater understanding of the contribution of integrin signalling to the role of T cells in autoimmune and inflammatory diseases has focused much attention on the development of therapeutics that target T-cell integrins. This literature review describes the structure, activation, and function of integrins with respect to T cells, then discusses the use of integrin-targeting therapeutics in inflammatory bowel disease, multiple sclerosis, and psoriasis. Efficacy and safety data from clinical trials and post-marketing surveillance are presented for currently approved therapeutics, therapeutics that have been withdrawn from the market, and novel therapeutics currently in clinical trials. This literature review will inform the reader of the current means of targeting T-cell integrins in autoimmune and inflammatory diseases, as well as recent developments in the field.

Understanding the molecular mechanisms of anti-trafficking therapies and their clinical relevance in inflammatory bowel disease

In patients with inflammatory bowel disease (IBD), a combination of dysbiosis, increased intestinal permeability, and insufficient regulatory responses facilitate the development of chronic inflammation, which is driven by a complex interplay between the mucosal immune system and the environment and sustained by immune priming and ongoing cellular recruitment to the gut. The localization of immune cells is mediated by their expression of chemokine receptors and integrins, which bind to chemokines and adhesion molecules, respectively. In this article, we review the mechanisms of action of anti-trafficking therapies for IBD and consider clinical observations in the context of the different mechanisms of action. Furthermore, we discuss the evolution of molecular resistance to anti-cytokines, in which the composition of immune cells in the gut changes in response to treatment, and the potential implications of this for treatment sequencing. Lastly, we discuss the relevance of mechanism of action to combination therapy for IBD.

Differential Effects of Ontamalimab Versus Vedolizumab on Immune Cell Trafficking in Intestinal Inflammation and Inflammatory Bowel Disease

BACKGROUND AND AIMS

The anti-MAdCAM-1 antibody ontamalimab demonstrated efficacy in a phase II trial in ulcerative colitis and results of early terminated phase III trials are pending, but its precise mechanisms of action are still unclear. Thus, we explored the mechanisms of action of ontamalimab and compared it to the anti-α4β7 antibody vedolizumab.

METHODS

We studied MAdCAM-1 expression with RNA sequencing and immunohistochemistry. The mechanisms of action of ontamalimab were assessed with fluorescence microscopy, dynamic adhesion and rolling assays. We performed in vivo cell trafficking studies in mice and compared ontamalimab and vedolizumab surrogate [-s] antibodies in experimental models of colitis and wound healing. We analysed immune cell infiltration under anti-MAdCAM-1 and anti-α4β7 treatment by single-cell transcriptomics and studied compensatory trafficking pathways.

RESULTS

MAdCAM-1 expression was increased in active inflammatory bowel disease. Binding of ontamalimab to MAdCAM-1 induced the internalization of the complex. Functionally, ontamalimab blocked T cell adhesion similar to vedolizumab, but also inhibited L-selectin-dependent rolling of innate and adaptive immune cells. Despite conserved mechanisms in mice, the impact of ontamalimab-s and vedolizumab-s on experimental colitis and wound healing was similar. Single-cell RNA sequencing demonstrated enrichment of ontamalimab-s-treated lamina propria cells in specific clusters, and in vitro experiments indicated that redundant adhesion pathways are active in these cells.

CONCLUSIONS

Ontamalimab has unique and broader mechanisms of action compared to vedolizumab. However, this seems to be compensated for by redundant cell trafficking circuits and leads to similar preclinical efficacy of anti-α4β7 and anti-MAdCAM-1 treatment. These results will be important for the interpretation of pending phase III data.

IL-3 receptor signalling suppresses chronic intestinal inflammation by controlling mechanobiology and tissue egress of regulatory T cells

IL-3 has been reported to be involved in various inflammatory disorders, but its role in inflammatory bowel disease (IBD) has not been addressed so far. Here, we determined IL-3 expression in samples from patients with IBD and studied the impact of Il3 or Il3r deficiency on T cell-dependent experimental colitis. We explored the mechanical, cytoskeletal and migratory properties of Il3r -/- and Il3r +/+ T cells using real-time deformability cytometry, atomic force microscopy, scanning electron microscopy, fluorescence recovery after photobleaching and in vitro and in vivo cell trafficking assays. We observed that, in patients with IBD, the levels of IL-3 in the inflamed mucosa were increased. In vivo, experimental chronic colitis on T cell transfer was exacerbated in the absence of Il-3 or Il-3r signalling. This was attributable to Il-3r signalling-induced changes in kinase phosphorylation and actin cytoskeleton structure, resulting in increased mechanical deformability and enhanced egress of Tregs from the inflamed colon mucosa. Similarly, IL-3 controlled mechanobiology in human Tregs and was associated with increased mucosal Treg abundance in patients with IBD. Collectively, our data reveal that IL-3 signaling exerts an important regulatory role at the interface of biophysical and migratory T cell features in intestinal inflammation and suggest that this might be an interesting target for future intervention.

Colitis-associated carcinogenesis: crosstalk between tumors, immune cells and gut microbiota

Colorectal cancer (CRC) is the third most common cancer worldwide. One of the main causes of colorectal cancer is inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD). Intestinal epithelial cells (IECs), intestinal mesenchymal cells (IMCs), immune cells, and gut microbiota construct the main body of the colon and maintain colon homeostasis. In the development of colitis and colitis-associated carcinogenesis, the damage, disorder or excessive recruitment of different cells such as IECs, IMCs, immune cells and intestinal microbiota play different roles during these processes. This review aims to discuss the various roles of different cells and the crosstalk of these cells in transforming intestinal inflammation to cancer, which provides new therapeutic methods for chemotherapy, targeted therapy, immunotherapy and microbial therapy.

Propionic Acid Driven by the Lactobacillus johnsonii Culture Supernatant Alleviates Colitis by Inhibiting M1 Macrophage Polarization by Modulating the MAPK Pathway in Mice

In this study, we investigated the effects of Lactobacillus johnsonii on the mouse colitis model. The results showed that the supernatant of the L. johnsonii culture alleviated colitis and remodeled gut microbiota, represented by an increased abundance of bacteria producing short-chain fatty acids, leading to an increased concentration of propionic acid in the intestine. Further studies revealed that propionic acid inhibited activation of the MAPK signaling pathway and polarization of M1 macrophages. Macrophage clearance assays confirmed that macrophages are indispensable for alleviating colitis through propionic acid. In vitro experiments showed that propionic acid directly inhibited the MAPK signaling pathway in macrophages and reduced M1 macrophage polarization, thereby inhibiting the secretion of pro-inflammatory cytokines. These findings improve our understanding of how L. johnsonii attenuates inflammatory bowel disease (IBD) and provide valuable insights for identifying molecular targets for IBD treatment in the future.

[Mechanism of action and exogenous supplementation of vitamin D in Crohn's disease]

Vitamin D can not only regulate calcium and phosphorus metabolism, but also exert an immunoregulatory effect. Vitamin D deficiency is common in patients with Crohn's disease (CD). Studies have shown that vitamin D is associated with CD and other autoimmune diseases and can improve the condition of patients with CD and promote their recovery by regulating intestinal immunity, repairing the intestinal mucosal barrier, inhibiting intestinal fibrosis, enhancing the response to infliximab, and regulating intestinal microbiota. Exogenous vitamin D supplementation can induce disease remission while increasing the serum level of vitamin D. However, only a few randomized, double-blind, and placebo-controlled trials have investigated the therapeutic effect of vitamin D in CD, and the optimal form of vitamin D supplementation, the specific dosage of vitamin D supplementation, and the optimal serum maintenance concentration of vitamin D remain to be clarified. This article mainly discusses the mechanism of action of vitamin D in CD and the beneficial effect of exogenous vitamin D supplementation on CD.

Uranium-bearing dust induces differentiation and expansion of enteroendocrine cells in human colonoids

Chronic exposure to environmental toxins and heavy metals has been associated with intestinal inflammation, increased susceptibility to pathogen-induced diseases, and higher incidences of colorectal cancer, all of which have been steadily increasing in prevalence for the past 40 years. The negative effects of heavy metals on barrier permeability and inhibition of intestinal epithelial healing have been described; however, transcriptomic changes within the intestinal epithelial cells and impacts on lineage differentiation are largely unknown. Uranium exposure remains an important environmental legacy and physiological health concern, with hundreds of abandoned uranium mines located in the Southwestern United States largely impacting underserved indigenous communities. Herein, using human colonoids, we defined the molecular and cellular changes that occur in response to uranium bearing dust (UBD) exposure. We used single cell RNA sequencing to define the molecular changes that occur to specific identities of colonic epithelial cells. We demonstrate that this environmental toxicant disrupts proliferation and induces hyperplastic differentiation of secretory lineage cells, particularly enteroendocrine cells (EEC). EECs respond to UBD exposure with increased differentiation into de novo EEC sub-types not found in control colonoids. This UBD-induced EEC differentiation does not occur via canonical transcription factors NEUROG3 or NEUROD1. These findings highlight the significance of crypts-based proliferative cells and secretory cell differentiation as major colonic responses to heavy metal-induced injury.

Gut-licensed β7+ CD4+ T cells contribute to progressive retinal ganglion cell damage in glaucoma

Glaucoma is the leading cause of irreversible blindness. Currently, most therapeutic strategies aim to reduce elevated intraocular pressure (EIOP), but this does not always halt disease progression. Evidence suggests a role for T cells in glaucoma pathogenesis, but the underlying mechanisms remain largely unknown. Here, we found that the percentage of circulating CD4+ T cells expressing a gut-homing integrin β7 was increased in patients with glaucoma and was associated with disease stage. In an EIOP-triggered glaucoma mouse model, β7+ CD4+ T cells infiltrated the retina in the progressive phase of glaucoma via eliciting retinal endothelial cell expression of mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1). MAdCAM-1 was minimally detected in retinas of healthy mice, and neutralization with an MAdCAM-1 antibody ameliorated retinal ganglion cell (RGC) loss and glial activity in mice with glaucoma. We furthermore found that EIOP-induced β7+ CD4+ T cells homed to the gut during the acute phase of glaucoma, which was essential for progressive RGC damage in diseased mice. Gut-homing β7+ CD4+ T cells underwent transcriptional reprogramming, showing up-regulated pathways enriched in autoimmune diseases, bacteria responses, mucosal immunity, and glial activity. Gut-homing β7+ CD4+ T cells gained the competence to induce retinal MAdCAM-1 expression and to cross the blood-retina barrier. Together, our study reveals a role of gut-licensed β7+ CD4+ T cells and MAdCAM-1 in RGC degeneration and emphasizes the importance of the "gut-retina" axis in glaucoma.

P62/SQSTM1 binds with claudin-2 to target for selective autophagy in stressed intestinal epithelium

Impaired autophagy promotes Inflammatory Bowel Disease (IBD). Claudin-2 is upregulated in IBD however its role in the pathobiology remains uncertain due to its complex regulation, including by autophagy. Irrespective, claudin-2 expression protects mice from DSS colitis. This study was undertaken to examine if an interplay between autophagy and claudin-2 protects from colitis and associated epithelial injury. Crypt culture and intestinal epithelial cells (IECs) are subjected to stress, including starvation or DSS, the chemical that induces colitis in-vivo. Autophagy flux, cell survival, co-immunoprecipitation, proximity ligation assay, and gene mutational studies are performed. These studies reveal that under colitis/stress conditions, claudin-2 undergoes polyubiquitination and P62/SQSTM1-assisted degradation through autophagy. Inhibiting autophagy-mediated claudin-2 degradation promotes cell death and thus suggest that claudin-2 degradation promotes autophagy flux to promote cell survival. Overall, these data inform for the previously undescribed role for claudin-2 in facilitating IECs survival under stress conditions, which can be harnessed for therapeutic advantages.

An Activation-Specific Anti-Mac-1 Designed-Ankyrin-Repeat-Protein Attenuates Colitis in Mice

(1) Background: Inflammatory bowel diseases are complex and multifactorial disorders of unknown etiology. The extravasation of activated leukocytes is a critical step in the pathogenesis of these diseases. Leukocyte integrin Mac-1 (α_Mβ₂; CD11b/CD18) is crucial for the extravasation of myeloid cells, and a novel activation-specific anti-Mac-1 Designed Ankyrin Repeat protein (DARPin F7) is a promising therapeutic agent for inflammatory diseases. In its activated conformation, Mac-1 expresses the high-affinity binding site I-domain, which the DARPin F7 selectively targets. In our study, we aimed to explore the therapeutic potential of anti-Mac-1 DARPin F7 in murine dextrane sodium sulfate (DSS)-induced colitis. (2) Methods: C57BL/6J mice received 3% DSS drinking water for five days, followed by normal drinking water for one week. The mice were treated with DARPin F7 or a control substance daily via intraperitoneal injections. Disease activity index (DAI), colon length, myeloperoxidase (MPO) activity measurements, H&E staining, and qRT-PCR were conducted after euthanizing the mice on day 12. (3) Results: Treatment with DARPin F7 resulted in less pronounced colon shortening and significantly lower histological scores. The DARPin F7-treated animals experienced substantially less disease and myeloperoxidase (MPO) activity. Animals that received DARPin F7 treatment suffered less weight loss and recovered from the weight loss more efficiently. Treatment with DARPin F7 also led to significantly reduced mRNA expression of inflammatory cytokines. (4) Conclusion: Anti-Mac-1 treatment markedly reduced disease activity and inflammatory reaction accompanying DSS-induced colitis in mice.

Recent advances in the treatment of IBD: Targets, mechanisms and related therapies

Inflammatory bowel disease (IBD), as a representative inflammatory disease, currently has multiple effective treatment options available and new therapeutic strategies are being actively explored to further increase the treatment options for patients with IBD. Furthermore, biologic agents and small molecule drugs developed for ulcerative colitis (UC) and Crohn's disease (CD) have evolved toward fewer side effects and more accurate targeting. Novel inhibitors that target cytokines (such as IL-12/23 inhibitors, PDE4 inhibitors), integrins (such as integrin inhibitors), cytokine signaling pathways (such as JAK inhibitors, SMAD7 blocker) and cell signaling receptors (such as S1P receptor modulator) have become the preferred treatment choice for many IBD patients. Conventional therapies such as 5-aminosalicylic acid, corticosteroids, immunomodulators and anti-tumor necrosis factor agents continue to demonstrate therapeutic efficacy, particularly in combination with drug therapy. This review integrates research from chemical, biological and adjuvant therapies to evaluate current and future IBD therapies, highlighting the mechanism of action of each therapy and emphasizing the potential of development prospects.

Manual cell selection in single cell transcriptomics using scSELpy supports the analysis of immune cell subsets

Introduction

Single cell RNA sequencing plays an increasing and indispensable role in immunological research such as in the field of inflammatory bowel diseases (IBD). Professional pipelines are complex, but tools for the manual selection and further downstream analysis of single cell populations are missing so far.

Methods

We developed a tool called scSELpy, which can easily be integrated into Scanpy-based pipelines, allowing the manual selection of cells on single cell transcriptomic datasets by drawing polygons on various data representations. The tool further supports the downstream analysis of the selected cells and the plotting of results.

Results

Taking advantage of two previously published single cell RNA sequencing datasets we show that this tool is useful for the positive and negative selection of T cell subsets implicated in IBD beyond standard clustering. We further demonstrate the feasibility for subphenotyping T cell subsets and use scSELpy to corroborate earlier conclusions drawn from the dataset. Moreover, we also show its usefulness in the context of T cell receptor sequencing.

Discussion

Collectively, scSELpy is a promising additive tool fulfilling a so far unmet need in the field of single cell transcriptomic analysis that might support future immunological research.

Oxidative Stress, Inflammation, Gut Dysbiosis: What Can Polyphenols Do in Inflammatory Bowel Disease?

Inflammatory bowel disease (IBD) is a long-term, progressive, and recurrent intestinal inflammatory disorder. The pathogenic mechanisms of IBD are multifaceted and associated with oxidative stress, unbalanced gut microbiota, and aberrant immune response. Indeed, oxidative stress can affect the progression and development of IBD by regulating the homeostasis of the gut microbiota and immune response. Therefore, redox-targeted therapy is a promising treatment option for IBD. Recent evidence has verified that Chinese herbal medicine (CHM)-derived polyphenols, natural antioxidants, are able to maintain redox equilibrium in the intestinal tract to prevent abnormal gut microbiota and radical inflammatory responses. Here, we provide a comprehensive perspective for implementing natural antioxidants as potential IBD candidate medications. In addition, we demonstrate novel technologies and stratagems for promoting the antioxidative properties of CHM-derived polyphenols, including novel delivery systems, chemical modifications, and combination strategies.

miR-146a-5p regulates autophagy and NLRP3 inflammasome activation in epithelial barrier damage in the in vitro cell model of ulcerative colitis through the RNF8/Notch1/mTORC1 pathway

Ulcerative colitis (UC) is a chronic inflammatory disease affecting the colon that can be influenced by microRNAs (miRNAs). This study aims to investigate the impact of miR-146a-5p on lipopolysaccharide (LPS)-induced Caco-2/HT-29 cell autophagy and NLRP3 inflammasome activation and the underlying mechanism, with the aim of identifying potential therapeutic targets. We used LPS to establish Caco-2/HT-29 cell models and measured cell viability by CCK-8. The levels of miR-146a-5p, RNF8, markers of NLRP3 inflammasome activation and autophagy, proteins involved in the Notch1/mTORC1 pathway, and inflammatory factors were assessed by RT-qPCR, Western blot, and ELISA. Intestinal epithelial barrier function was evaluated by measuring transepithelial electrical resistance. Autophagic flux was measured using tandem fluorescent-labeled LC3. miR-146a-5p was highly-expressed in LPS-induced Caco-2/HT-29 cells, and autophagy flux was blocked at the autolysosomal stage after LPS induction. Inhibition of miR-146a-5p suppressed NLRP3 inflammasome activation, reduced intestinal epithelial barrier damage, and facilitated autophagy inhibition in LPS-induced Caco-2/HT-29 cells. The autophagy inhibitor NH4Cl partially nullified the inhibitory effects of miR-146a-5p inhibition on NLRP3 inflammation activation. miR-146a-5p targeted RNF8, and silencing RNF8 partly abrogated the action of miR-146a-5p inhibition on promoting autophagy and inhibiting NLRP3 inflammasome activation. miR-146a-5p inhibition suppressed the Notch1/mTORC1 pathway activation by upregulating RNF8. Inhibition of the Notch1/mTORC1 pathway partially nullified the function of silencing RNF8 on inhibiting autophagy and bolstering NLRP3 inflammasome activation. In conclusion, miR-146a-5p inhibition may be a potential therapeutic approach for UC, as it facilitates autophagy of LPS-stimulated Caco-2/HT-29 cells, inhibits NLRP3 inflammasome activation, and reduces intestinal epithelial barrier damage by upregulating RNF8 and suppressing the Notch1/mTORC1 pathway.

Colon-specific delivery of methotrexate using hyaluronic acid modified pH-responsive nanocarrier for the therapy of colitis in mice

Oral immunosuppressant methotrexate (MTX) is an effective method for the treatment of inflammatory bowel disease (IBD). To overcome the defects of clinical application of MTX, poly (lactic-co-glycolic acid) (PLGA), Eudragits® S100 (ES100), chitosan (CS) and hyaluronic acid (HA) were used to structure the MTX-loaded HA-CS/ES100/PLGA nanoparticles (MTX@hCEP). MTX@hCEP had a hydrodynamic particle size of approximately 202.5 nm, narrow size distribution, negative zeta potential (-18.7 mV), and smooth surface morphology. In vitro drug release experiments under simulated gastrointestinal conditions indicated that MTX@hCEP exhibited colonic pH-sensitive drug release properties. The cellular uptake capacity of hCEP nanoparticles was significantly enhanced in RAW 264.7 macrophages. Moreover, we further found that the MTX@hCEP also inhibited the proliferation and the secretion of pro-inflammatory cytokines in the LPS-stimulated macrophages. In vivo imaging results not only demonstrated that the accumulated in the colon of colitis mice, but also indicated the extended retention time of MTX in the colon. Additionally, MTX@hCEP alleviated inflammatory symptoms via decreasing the activities of myeloperoxidase and pro-inflammatory factors, promoting mucosal repair in vivo. Collectively, these results clearly demonstrated that MTX@hCEP with properties of colon-specific and macrophages targeting can be exploited as an efficient nanotherapeutic for IBD therapy.

Force-Regulated Calcium Signaling of Lymphoid Cell RPMI 8226 Mediated by Integrin α4β7/MAdCAM-1 in Flow

MAdCAM-1 binds to integrin α₄β₇, which mediates the rolling and arrest of circulating lymphocytes upon the vascular endothelia during lymphocytic homing. The calcium response by adhered lymphocytes is a critical event for lymphocyte activation and subsequent arrest and migration under flow. However, whether the interaction of integrin α₄β₇ /MAdCAM-1 can effectively trigger the calcium response of lymphocytes remains unclear, as well as whether the fluid force affects the calcium response. In this study, we explore the mechanical regulation of integrin α₄β₇-induced calcium signaling under flow. Flou-4 AM was used to examine the calcium response under real-time fluorescence microscopy when cells were firmly adhered to a parallel plate flow chamber. The interaction between integrin α₄β₇ and MAdCAM-1 was found to effectively trigger calcium signaling in firmly adhered RPMI 8226 cells. Meanwhile, increasing fluid shear stress accelerated the cytosolic calcium response and enhanced signaling intensity. Additionally, the calcium signaling of RPMI 8226 activated by integrin α₄β₇ originated from extracellular calcium influx instead of cytoplasmic calcium release, and the signaling transduction of integrin α₄β₇ was involved in Kindlin-3. These findings shed new light on the mechano-chemical mechanism of calcium signaling in RPMI 8226 cells induced by integrin α₄β_7.

Expression and function of α4β7 integrin predict the success of vedolizumab treatment in inflammatory bowel disease

Inflammatory bowel diseases are medically intractable and require constant therapy in many cases. While a growing number of biologicals and small molecules is available for treatment, a substantial portion of patients experiences primary non-response to these compounds and head-to-head evidence for therapy selection is scarce. Thus, approaches to predict treatment success in individual patients are a huge unmet need. We had previously suggested that the expression and function of α4β7 integrin on T cells in the peripheral blood correlate to outcomes of therapy with the anti-α4β7 integrin antibody vedolizumab. Here, we conducted a translational multicenter trial to prospectively evaluate this hypothesis. In a cohort of 89 patients with inflammatory bowel disease undergoing regular therapy with vedolizumab, lower baseline expression of α4β7 was associated with short-term clinical response. Consistently, low α4β7 expression in patients achieving remission predicted sustained remission in week 30. Moreover, high dynamic adhesion of CD4⁺ T cells to MAdCAM-1 and high reduction of adhesion by vedolizumab in vitro at baseline were associated with clinical remission. These data substantiate the potential of α4β7 integrin function and expression to forecast outcomes of vedolizumab therapy. Further translational efforts are necessary to improve the performance of the assays and to implement the concept in clinical practice.

Integrated multiple microarray studies by robust rank aggregation to identify immune-associated biomarkers in Crohn's disease based on three machine learning methods

Crohn's disease (CD) is a complex autoimmune disorder presumed to be driven by complex interactions of genetic, immune, microbial and even environmental factors. Intrinsic molecular mechanisms in CD, however, remain poorly understood. The identification of novel biomarkers in CD cases based on larger samples through machine learning approaches may inform the diagnosis and treatment of diseases. A comprehensive analysis was conducted on all CD datasets of Gene Expression Omnibus (GEO); our team then used the robust rank aggregation (RRA) method to identify differentially expressed genes (DEGs) between controls and CD patients. PPI (protein‒protein interaction) network and functional enrichment analyses were performed to investigate the potential functions of the DEGs, with molecular complex detection (MCODE) identifying some important functional modules from the PPI network. Three machine learning algorithms, support vector machine-recursive feature elimination (SVM-RFE), random forest (RF), and least absolute shrinkage and selection operator (LASSO), were applied to determine characteristic genes, which were verified by ROC curve analysis and immunohistochemistry (IHC) using clinical samples. Univariable and multivariable logistic regression were used to establish a machine learning score for diagnosis. Single-sample GSEA (ssGSEA) was performed to examine the correlation between immune infiltration and biomarkers. In total, 5 datasets met the inclusion criteria: GSE75214, GSE95095, GSE126124, GSE179285, and GSE186582. Based on RRA integrated analysis, 203 significant DEGs were identified (120 upregulated genes and 83 downregulated genes), and MCODE revealed some important functional modules in the PPI network. Machine learning identified LCN2, REG1A, AQP9, CCL2, GIP, PROK2, DEFA5, CXCL9, and NAMPT; AQP9, PROK2, LCN2, and NAMPT were further verified by ROC curves and IHC in the external cohort. The final machine learning score was defined as [Expression level of AQP9 × (2.644)] + [Expression level of LCN2 × (0.958)] + [Expression level of NAMPT × (1.115)]. ssGSEA showed markedly elevated levels of dendritic cells and innate immune cells, such as macrophages and NK cells, in CD, consistent with the gene enrichment results that the DEGs are mainly involved in the IL-17 signaling pathway and humoral immune response. The selected biomarkers analyzed by the RRA method and machine learning are highly reliable. These findings improve our understanding of the molecular mechanisms of CD pathogenesis.

Combination Therapy with Indigo and Indirubin for Ulcerative Colitis via Reinforcing Intestinal Barrier Function

Indigo and indirubin, the active molecules of traditional Chinese medicine indigo naturalis, exert therapeutic activity for ulcerative colitis (UC). Indigo and indirubin are isomers and have distinctive profiles in anti-inflammation, immune regulation, intestinal microbiota regulation, oxidative stress regulation, and intestinal mucosal repair for UC treatment. Thus, exploring its combined administration's integrated advantages for UC is critical. This study is aimed at clarifying the effect and mechanisms of the combined administration of indigo and indirubin on colitis mouse models. The results showed that all the treatment groups could improve the disease symptoms, and the combined administration showed the best effect. Additionally, compared with indigo and indirubin alone, the combination group could significantly reinforce intestinal barrier function by increasing the expression of E-cadherin, occludin, ZO-1, and MUC2 and improving intestinal permeability. The treatment groups significantly improved the expression of cytokines, including TNF-α, IFN-γ, IL-12, IL-23, and IL-17A, and indirubin presented the most potent anti-inflammatory effect. Furthermore, all the treatment groups reduced the infiltration of the immune cells in intestinal lamina propria and the production of ROS/RNS. Notably, indigo exhibited a more substantial capacity to regulate natural killer (NK) cells, ILC3, neutrophils, and dendritic cells, followed by the combination group and indirubin alone. Finally, all the treatment groups modulated intestinal microbiota composition, increased the proportion of beneficial microbiota, and decreased the proportion of microbiota. Our results indicated that indigo and indirubin synergistically reinforced the intestinal barrier function, which may be associated with integrating the indirubin anti-inflammatory and intestinal microbiota regulating strength and indigo immune and ROS/RNS regulation advantage.

Selective Transcription Factor Blockade Reduces Human Retinal Endothelial Cell Expression of Intercellular Adhesion Molecule-1 and Leukocyte Binding

The interaction between leukocytes and cytokine-activated retinal endothelium is an initiating step in non-infectious uveitis involving the posterior eye, mediated by cell adhesion molecules. However, because cell adhesion molecules are required for immune surveillance, therapeutic interventions would ideally be employed indirectly. Using 28 primary human retinal endothelial cell isolates, this study sought to identify transcription factor targets for reducing levels of the key retinal endothelial cell adhesion molecule, intercellular adhesion molecule (ICAM)-1, and limiting leukocyte binding to the retinal endothelium. Five candidate transcription factors-C2CD4B, EGR3, FOSB, IRF1, and JUNB-were identified by differential expression analysis of a transcriptome generated from IL-1β- or TNF-α-stimulated human retinal endothelial cells, interpreted in the context of the published literature. Further filtering involved molecular studies: of the five candidates, C2CD4B and IRF1 consistently demonstrated extended induction in IL-1β- or TNF-α-activated retinal endothelial cells and demonstrated a significant decrease in both ICAM-1 transcript and ICAM-1 membrane-bound protein expression by cytokine-activated retinal endothelial cells following treatment with small interfering RNA. RNA interference of C2CD4B or IRF1 significantly reduced leukocyte binding in a majority of human retinal endothelial cell isolates stimulated by IL-1β or TNF-α. Our observations suggest that the transcription factors C2CD4B and IRF1 may be potential drug targets for limiting leukocyte-retinal endothelial cell interactions in non-infectious uveitis involving the posterior eye.

Controlling in and out - the future of interfering with immune cell trafficking in inflammatory bowel disease

INTRODUCTION

Immune cell trafficking is a key requirement in the pathogenesis of inflammatory bowel diseases. Consistently, therapeutic strategies to target immune cell trafficking have been established and continue to be developed for the treatment of ulcerative colitis and Crohn's disease.

AREAS COVERED

In this review, we briefly summarize the most important checkpoints of intestinal immune cell trafficking and their importance during IBD. Moreover, we provide an overview of associated therapeutic targets and previous as well as current efforts on treatment strategies related to these targets.

EXPERT OPINION

Finally, we comment on potential future developments that might shape the field of immune cell trafficking in the context of IBD.

Intestinal Barrier Dysfunction and Microbial Translocation in Patients with First-Diagnosed Atrial Fibrillation

BACKGROUND

According to the leaky gut concept, microbial products (e.g., lipopolysaccharide, LPS) enter the circulation and mediate pro-inflammatory immunological responses. Higher plasma LPS levels have been reported in patients with various cardiovascular diseases, but not specifically during early atrial fibrillation (AF).

METHODS

We studied data and blood samples from patients presenting with first-diagnosed AF (FDAF) (n = 80) and 20 controls.

RESULTS

Circulating biomarkers that are suggestive of mucosal inflammation (zonulin, mucosal adhesion molecule MAdCAM-1) and intestinal epithelium damage (intestinal fatty acid binding protein, IFABP) were increased in the plasma of patients with FDAF when compared to patients with chronic cardiovascular diseases but without AF. Surrogate plasma markers of increased intestinal permeability (LPS, CD14, LPS-binding protein, gut-derived LPS-neutralising IgA antibodies, EndoCAbs) were detected during early AF. A reduced ratio of IgG/IgM EndoCAbs titres indicated chronic endotoxaemia. Collagen turnover biomarkers, which corresponded to the LPS values, suggested an association of gut-derived low-grade endotoxaemia with adverse structural remodelling. The LPS concentrations were higher in FDAF patients who experienced a major adverse cardiovascular event.

CONCLUSIONS

Intestinal barrier dysfunction and microbial translocation accompany FDAF. Improving gut permeability and low-grade endotoxaemia might be a potential therapeutic approach to reducing the disease progression and cardiovascular complications in FDAF.

Gut immune cell trafficking: inter-organ communication and immune-mediated inflammation

Immune cell trafficking is a complex and tightly regulated process that is indispensable for the body's fight against pathogens. However, it is also increasingly acknowledged that dysregulation of cell trafficking contributes to the pathogenesis of immune-mediated inflammatory diseases (IMIDs) in gastroenterology and hepatology, such as inflammatory bowel disease and primary sclerosing cholangitis. Moreover, altered cell trafficking has also been implicated as a crucial step in the immunopathogenesis of other IMIDs, such as rheumatoid arthritis and multiple sclerosis. Over the past few years, a central role of the gut in mediating these disorders has progressively emerged, and the partly microbiota-driven imprinting of particular cell trafficking phenotypes in the intestine seems to be crucially involved. Therefore, this Review highlights achievements in understanding immune cell trafficking to, within and from the intestine and delineates its consequences for immune-mediated pathology along the gut-liver, gut-joint and gut-brain axes. We also discuss implications for current and future therapeutic approaches that specifically interfere with homing, retention, egress and recirculation of immune cells.

The shaping of gut immunity in cirrhosis

Cirrhosis is the common end-stage of chronic liver diseases of different etiology. The altered bile acids metabolism in the cirrhotic liver and the increase in the blood-brain barrier permeability, along with the progressive dysbiosis of intestinal microbiota, contribute to gut immunity changes, from compromised antimicrobial host defense to pro-inflammatory adaptive responses. In turn, these changes elicit a disruption in the epithelial and gut vascular barriers, promoting the increased access of potential pathogenic microbial antigens to portal circulation, further aggravating liver disease. After summarizing the key aspects of gut immunity during homeostasis, this review is intended to update the contribution of liver and brain metabolites in shaping the intestinal immune status and, in turn, to understand how the loss of homeostasis in the gut-associated lymphoid tissue, as present in cirrhosis, cooperates in the advanced chronic liver disease progression. Finally, several therapeutic approaches targeting the intestinal homeostasis in cirrhosis are discussed.

Mucosal addressin cell adhesion molecule 1 expression reflects mucosal inflammation and subsequent relapse in patients with ulcerative colitis

BACKGROUND AND AIMS

Mucosal addressin cell adhesion molecule 1 (MAdCAM-1) is upregulated in the vascular endothelium of the colonic mucosa in ulcerative colitis (UC). Although the association between MAdCAM-1 expression and mucosal inflammation has been discussed, the association with the clinical course of UC patients has not been reported. In this study we investigated not only the association between mucosal MAdCAM-1 expression and mucosal inflammation, but also its association with subsequent relapse in UC patients with clinical remission.

METHODS

Eighty UC patients in remission who visited Kyoto Prefectural University of Medicine for follow-up for 2 years were included. Biopsy samples were collected during colonoscopy, and transcriptional expression levels of UC-related cytokines and MAdCAM-1 were quantified using real-time polymerase chain reaction. MAdCAM-1 mRNA expression and protein expression by immunohistochemistry was compared in patients who subsequently relapsed and those who remained in remission and examined in relation to endoscopic findings, histologic activity, and cytokine expression.

RESULTS

MAdCAM-1 expression was correlated with endoscopic severity, and significantly elevated in histological active mucosa than inactive mucosa. Furthermore, MAdCAM-1 expression levels were closely correlated with those of several cytokines. MAdCAM-1 mRNA and protein expression were significantly higher in the relapse group than in the remission group, indicating that MAdCAM-1 expression in the mucosa is already elevated in UC patients in clinical remission who subsequently relapse.

CONCLUSIONS

MAdCAM-1 expression in the colonic mucosa of UC patients related to mucosal inflammation and subsequent relapse; it may serve as a marker for both relapse and therapeutic effectiveness in UC.

Autologous organoid co-culture model reveals T cell-driven epithelial cell death in Crohn's Disease

Lympho-epithelial interactions between intestinal T resident memory cells (Trm) and the epithelium have been associated with inflammatory bowel disease (IBD) activity. We developed ex vivo autologous organoid-mucosal T cell cocultures to functionally assess lymphoepithelial interactions in Crohn's Disease (CD) patients compared to controls. We demonstrate the direct epithelial cell death induced by autologous mucosal T cells in CD patients but not in controls. These findings were positively correlated with T cell infiltration of the organoids. This potential was inhibited by limiting lympho-epithelial interactions through CD103 and NKG2D blocking antibodies. These data directly demonstrate for the first time the direct deleterious effect of mucosal T cells on the epithelium of CD patients. Such ex-vivo models are promising techniques to unravel the pathophysiology of these diseases and the potential mode of action of current and future therapies.