Patients with inflammatory bowel disease (IBD) reveal increased induction capacity of intracellular interferon-gamma (IFN-gamma) in peripheral CD8+ lymphocytes co-cultured with intestinal epithelial cells

Potential shared pathogenic mechanisms between endometriosis and inflammatory bowel disease indicate a strong initial effect of immune factors

Introduction

Over the past decades, immune dysregulation has been consistently demonstrated being common charactoristics of endometriosis (EM) and Inflammatory Bowel Disease (IBD) in numerous studies. However, the underlying pathological mechanisms remain unknown. In this study, bioinformatics techniques were used to screen large-scale gene expression data for plausible correlations at the molecular level in order to identify common pathogenic pathways between EM and IBD.

Methods

Based on the EM transcriptomic datasets GSE7305 and GSE23339, as well as the IBD transcriptomic datasets GSE87466 and GSE126124, differential gene analysis was performed using the limma package in the R environment. Co-expressed differentially expressed genes were identified, and a protein-protein interaction (PPI) network for the differentially expressed genes was constructed using the 11.5 version of the STRING database. The MCODE tool in Cytoscape facilitated filtering out protein interaction subnetworks. Key genes in the PPI network were identified through two topological analysis algorithms (MCC and Degree) from the CytoHubba plugin. Upset was used for visualization of these key genes. The diagnostic value of gene expression levels for these key genes was assessed using the Receiver Operating Characteristic (ROC) curve and Area Under the Curve (AUC) The CIBERSORT algorithm determined the infiltration status of 22 immune cell subtypes, exploring differences between EM and IBD patients in both control and disease groups. Finally, different gene expression trends shared by EM and IBD were input into CMap to identify small molecule compounds with potential therapeutic effects.

Results

113 differentially expressed genes (DEGs) that were co-expressed in EM and IBD have been identified, comprising 28 down-regulated genes and 86 up-regulated genes. The co-expression differential gene of EM and IBD in the functional enrichment analyses focused on immune response activation, circulating immunoglobulin-mediated humoral immune response and humoral immune response. Five hub genes (SERPING1、VCAM1、CLU、C3、CD55) were identified through the Protein-protein Interaction network and MCODE.High Area Under the Curve (AUC) values of Receiver Operating Characteristic (ROC) curves for 5hub genes indicate the predictive ability for disease occurrence.These hub genes could be used as potential biomarkers for the development of EM and IBD. Furthermore, the CMap database identified a total of 9 small molecule compounds (TTNPB、CAY-10577、PD-0325901 etc.) targeting therapeutic genes for EM and IBD.

Discussion

Our research revealed common pathogenic mechanisms between EM and IBD, particularly emphasizing immune regulation and cell signalling, indicating the significance of immune factors in the occurence and progression of both diseases. By elucidating shared mechanisms, our study provides novel avenues for the prevention and treatment of EM and IBD.

Paeoniflorin improves ulcerative colitis via regulation of PI3K‑AKT based on network pharmacology analysis

Paeoniflorin (PF) is the primary component derived from Paeonia lactiflora and white peony root and has been used widely for the treatment of ulcerative colitis (UC) in China. UC primarily manifests as a chronic inflammatory response in the intestine. In the present study, a network pharmacology approach was used to explore the specific effects and underlying mechanisms of action of PF in the treatment of UC. A research strategy based on network pharmacology, combining target prediction, network construction, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and molecular docking simulation was used to predict the targets of PF. A total of 288 potential targets of PF and 599 UC-related targets were identified. A total of 60 therapeutic targets of PF against UC were identified. Of these, 20 core targets were obtained by protein-protein interaction network construction. GO and KEGG pathway analyses showed that PF alleviated UC through EGFR tyrosine kinase inhibitor resistance, the IL-17 signaling pathway, and the PI3K/AKT signaling pathway. Molecular docking simulation showed that AKT1 and EGFR had good binding energy with PF. Animal-based experiments revealed that the administration of PF ameliorated the colonic pathological damage in a dextran sulfate sodium-induced mouse model, resulting in lower levels of proinflammatory cytokines including IL-1β, IL-6, and TNF-α, and higher levels of IL-10 and TGF-β. PF decreased the mRNA and protein expression levels of AKT1, EGFR, mTOR, and PI3K. These findings suggested that PF plays a therapeutic protective role in the treatment of UC by regulating the PI3K/AKT signaling pathway.

Major basic protein is a useful marker to distinguish eosinophilic esophagitis from IBD-associated eosinophilia in children

OBJECTIVES

The incidence of eosinophilic esophagitis (EoE) is 3-5 times greater in patients with inflammatory bowel disease (IBD) compared with the general population. This study aimed to differentiate true EoE from esophageal eosinophilia in IBD patients by evaluating expression of major basic protein (MBP) and interleukin-13 (IL-13) in esophageal biopsies.

METHODS

This retrospective study included subjects who had an esophagogastroduodenoscopy with esophageal biopsies for IBD work up or suspicion for EoE. Patients were classified into 5 groups: EoE with ≥15 eosinophils per high power field (eos/hpf), EoE-IBD with ≥15 eos/hpf, IBD eosinophilia with 1-14 eos/hpf, IBD and control groups. Biopsies were stained with MBP and IL-13 antibodies and the results (% staining/total tissue area), demographic, and clinical findings were compared among the groups.

RESULTS

The median for MBP staining levels in EoE-IBD was 3.8 (interquartile range 1.3-23), significantly lower than in EoE at 52.8 (8.3-113.2), but higher than in IBD eosinophilia at 0.2 (0-0.9; p < 0.001) and negligible in the IBD and control groups. IL-13 expression in EoE was significantly higher only compared with IBD and controls not with EoE-IBD or IBD eosinophilia. MBP predicted EoE with 100% sensitivity and 99% specificity while IL-13 had 83% sensitivity and 90% specificity using cutoff point from the cohort without EoE-IBD patients. Based on MBP cutoff point that distinguished EoE from non EoE, 56% in EoE-IBD were MBP-positive whereas 100% in EoE group (p < 0.05).

CONCLUSIONS

MBP may be an excellent marker in distinguishing true EoE from eosinophilia caused by IBD. Our data implied that MBP together with endoscopic and histologic changes can assist EoE diagnosis in IBD patients.

Posttranscriptional Events Orchestrate Immune Homeostasis of CD8+ T Cells

Maintaining immune homeostasis is instrumental for host health. Immune cells, such as T cells, are instrumental for the eradication of pathogenic bacteria, fungi and viruses. Furthermore, T cells also play a major role in the fight against cancer. Through the formation of immunological memory, a pool of antigen-experienced T cells remains in the body to rapidly protect the host upon reinfection or retransformation. In order to perform their protective function, T cells produce cytolytic molecules, such as granzymes and perforin, and cytokines such as interferon γ and tumor necrosis factor α. Recently, it has become evident that posttranscriptional regulatory events dictate the kinetics and magnitude of cytokine production by murine and human CD8+ T cells. Here, the recent literature regarding the role posttranscriptional regulation plays in maintaining immune homeostasis of antigen-experienced CD8+ T cells is reviewed.

Immune regulation and inflammation inhibition of Arctium lappa L. polysaccharides by TLR4/NF-κB signaling pathway in cells

Arctium lappa L. polysaccharides (ALP) are important active ingredients of burdocks with various bioactivities. In the present study, a crude polysaccharide was extracted from A. lappa L. roots and purified using DEAE-52 and Sephacryl™ S-400 columns to reach 99 % purity. This neutral polysaccharide contained fructose, glucose, galactose and arabinose in a ratio of 0.675:0.265:0.023:0.016 and had a Mw of 4256 Da. The immunomodulatory activity and intestinal inflammation inhibitory effects of ALP were investigated in in vitro models, including lipopolysaccharide-induced macrophage RAW264.7 and interleukin (IL)-1β-induced colon Caco-2 cells. The results revealed that ALP possessed both antioxidant and anti-inflammatory effects by decreasing nuclear factor-E2-related factor 2 mRNA expression and reactive oxygen species. Furthermore, ALP was found to have inhibitory effects on pro-inflammatory cytokines, including IL-8, IL-6, IL-1β, and tumor necrosis factor-α, as well as inflammatory cytokines, such as intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and monocyte chemoattractant protein-1 by down-regulating the Toll-like receptor 4 (TLR4)/NF-κB (nuclear factor-kappa B signaling) pathway. It indicated that A. lappa L. was an ideal source of bioactive polysaccharides having potential to be developed as functional foods or nutraceuticals to improve immune system and prevent/treat intestinal inflammation.

Immunoepigenetic Regulation of Inflammatory Bowel Disease: Current Insights into Novel Epigenetic Modulations of the Systemic Immune Response

The immune system and environmental factors are involved in various diseases, such as inflammatory bowel disease (IBD), through their effect on genetics, which modulates immune cells. IBD encompasses two main phenotypes, Crohn’s disease, and ulcerative colitis, which are manifested as chronic and systemic relapse-remitting gastrointestinal tract disorders with rising global incidence and prevalence. The pathophysiology of IBD is complex and not fully understood. Epigenetic research has resulted in valuable information for unraveling the etiology of this immune-mediated disease. Thus, the main objective of the present review is to summarize the current findings on the role of epigenetic mechanisms in IBD to shed light on their potential clinical relevance. This review focuses on the latest evidence regarding peripheral blood mononuclear cells and epigenetic changes in histone modification, DNA methylation, and telomere shortening in IBD. The various identified epigenetic DNA profiles with clinical value in IBD could be used as biomarkers for more accurately predicting disease development, treatment response, and therapy-related adverse events. Ultimately, the information presented here could be of potential relevance for future clinical practice in developing more efficient and precise medicine to improve the quality of life for patients with IBD.

Inflammatory bowel disease addressed by Caco-2 and monocyte-derived macrophages: an opportunity for an in vitro drug screening assay

Inflammatory bowel disease (IBD) is a widespread disease, affecting a growing demographic. The treatment of chronic inflammation located in the GI-tract is dependent on the severity; therefore, the IBD treatment pyramid is commonly applied. Animal experimentation plays a key role for novel IBD drug development; nevertheless, it is ethically questionable and limited in its throughput. Reliable and valid in vitro assays offer the opportunity to overcome these limitations. We combined Caco-2 with monocyte-derived macrophages and exposed them to known drugs, targeting an in vitro-in vivo correlation (IVIVC) with a focus on the severity level and its related drug candidate. This co-culture assay addresses namely the intestinal barrier and the immune response in IBD. The drug efficacy was analyzed by an LPS-inflammation of the co-culture and drug exposure according to the IBD treatment pyramid. Efficacy was defined as the range between LPS control (0%) and untreated co-culture (100%) independent of the investigated read-out (TEER, Papp, cytokine release: IL-6, IL-8, IL-10, TNF-α). The release of IL-6, IL-8, and TNF-α was identified as an appropriate readout for a fast drug screening ("yes-no response"). TEER showed a remarkable IVIVC correlation to the human treatment pyramid (5-ASA, Prednisolone, 6-mercaptopurine, and infliximab) with an R2 of 0.68. Similar to the description of an adverse outcome pathway (AOP) framework, we advocate establishing an "Efficacy Outcome Pathways (EOPs)" framework for drug efficacy assays. The in vitro assay offers an easy and scalable method for IBD drug screening with a focus on human data, which requires further validation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s44164-022-00035-8.

Cross-tissue, single-cell stromal atlas identifies shared pathological fibroblast phenotypes in four chronic inflammatory diseases

BACKGROUND

Pro-inflammatory fibroblasts are critical for pathogenesis in rheumatoid arthritis, inflammatory bowel disease, interstitial lung disease, and Sjögren's syndrome and represent a novel therapeutic target for chronic inflammatory disease. However, the heterogeneity of fibroblast phenotypes, exacerbated by the lack of a common cross-tissue taxonomy, has limited our understanding of which pathways are shared by multiple diseases.

METHODS

We profiled fibroblasts derived from inflamed and non-inflamed synovium, intestine, lungs, and salivary glands from affected individuals with single-cell RNA sequencing. We integrated all fibroblasts into a multi-tissue atlas to characterize shared and tissue-specific phenotypes.

FINDINGS

Two shared clusters, CXCL10+CCL19+ immune-interacting and SPARC+COL3A1+ vascular-interacting fibroblasts, were expanded in all inflamed tissues and mapped to dermal analogs in a public atopic dermatitis atlas. We confirmed these human pro-inflammatory fibroblasts in animal models of lung, joint, and intestinal inflammation.

CONCLUSIONS

This work represents a thorough investigation into fibroblasts across organ systems, individual donors, and disease states that reveals shared pathogenic activation states across four chronic inflammatory diseases.

FUNDING

Grant from F. Hoffmann-La Roche (Roche) AG.

Tofacitinib Downregulates TNF and Poly(I:C)-Dependent MHC-II Expression in the Colonic Epithelium

Major Histocompatibility Complex (MHC)-I and -II genes are upregulated in intestinal epithelial cells (IECs) during active inflammatory bowel diseases (IBD), but little is known about how IBD-relevant pro-inflammatory signals and IBD drugs can regulate their expression. We have previously shown that the synthetic analog of double-stranded RNA (dsRNA) Polyinosinic:polycytidylic acid (Poly(I:C)), induces interferon stimulated genes (ISGs) in colon organoids (colonoids). These ISGs may be involved in the induction of antigen presentation. In the present study, we applied colonoids derived from non-IBD controls and ulcerative colitis patients to identify induction and effects of IBD-drugs on antigen presentation in IECs in the context of Tumor Necrosis Factor (TNF)-driven inflammation. By RNA sequencing, we show that a combination of TNF and Poly(I:C) strongly induced antigen-presentation gene signatures in colonoids, including expression of MHC-II genes. MHC-I and -II protein expression was confirmed by immunoblotting and immunofluorescence. TNF+Poly(I:C)-dependent upregulation of MHC-II expression was associated with increased expression of Janus Kinases JAK1/2 as well as increased activation of transcription factor Signal transducer and activator of transcription 1 (STAT1). Accordingly, pre-treatment of colonoids with IBD-approved pan-Janus Kinase (JAK) inhibitor Tofacitinib led to the downregulation of TNF+Poly(I:C)-dependent MHC-II expression associated with the abrogation of STAT1 activation. Pre-treatment with corticosteroid Budesonide, commonly used in IBD, did not alter MHC-II expression. Collectively, our results identify a regulatory role for IBD-relevant pro-inflammatory signals on MHC-II expression that is influenced by Tofacitinib.

Limited Dose-Dependent Effects of Vedolizumab on Various Leukocyte Subsets

OBJECTIVES

The anti-α4β7 integrin antibody vedolizumab (VDZ) is successfully used for the treatment of inflammatory bowel diseases. However, only a subgroup of patients respond to therapy. VDZ is administered at a fixed dose, leading to a wide range of serum concentrations in patients. Previous work from our group showed a dose-dependent preferential binding of VDZ to effector compared with regulatory CD4 + T cells. Therefore, we aimed to determine the dose-dependent binding profile of VDZ to other leukocyte subsets.

METHODS

We characterized α4β7 integrin expression on CD8 + T cells, CD19 + B cells, CD14 + monocytes, natural killer cells, and eosinophils from patients with inflammatory bowel disease and healthy controls. We studied the binding of VDZ to these cells at different concentrations and investigated the functional consequences for dynamic adhesion and transmigration in vitro .

RESULTS

The expression of α4β7 differed between the analyzed leukocyte subsets and was significantly higher on eosinophils from inflammatory bowel disease patients compared with controls. Almost all α4β7-expressing cells from these subsets were bound by VDZ at a concentration of 10 μg/mL. Dynamic cell adhesion was significantly impaired in all subsets, but there were no dose-dependent differences in the inhibition of adhesion.

DISCUSSION

Our data suggest that α4β7-expressing CD8 + T cells, CD19 + B cells, CD14 + monocytes, natural killer cells, and eosinophils are a target of VDZ. However, there do not seem to be concentration-dependent differences, regarding the effects on these cells in the clinically relevant range. Thus, the reported exposure-efficacy characteristic of VDZ can probably mainly be attributed to CD4 + T-cell subsets.

Intestinal organoids in coculture: redefining the boundaries of gut mucosa ex vivo modeling

All-time preservation of an intact mucosal barrier is crucial to ensuring intestinal homeostasis and, hence, the organism's overall health maintenance. This complex process relies on an equilibrated signaling system between the intestinal epithelium and numerous cell populations inhabiting the gut mucosa. Any perturbations of this delicate cross talk, particularly regarding the immune cell compartment and microbiota, may sustainably debilitate the intestinal barrier function. As a final joint event, a critical rise in epithelial permeability facilitates the exposure of submucosal immunity to microbial antigens, resulting in uncontrolled inflammation, collateral tissue destruction, and dysbiosis. Organoid-derived intestinal coculture models have established themselves as convenient tools to reenact such pathophysiological events, explore interactions between selected cell populations, and assess their roles with a central focus on intestinal barrier recovery and stabilization.

Post-transcriptional control of T-cell cytokine production: Implications for cancer therapy

As part of the adaptive immune system, T cells are vital for the eradication of infected and malignantly transformed cells. To perform their protective function, T cells produce effector molecules that are either directly cytotoxic, such as granzymes, perforin, interferon-γ and tumour necrosis factor α, or attract and stimulate (immune) cells, such as interleukin-2. As these molecules can also induce immunopathology, tight control of their production is required. Indeed, inflammatory cytokine production is regulated on multiple levels. Firstly, locus accessibility and transcription factor availability and activity determine the amount of mRNA produced. Secondly, post-transcriptional mechanisms, influencing mRNA splicing/codon usage, stability, decay, localization and translation rate subsequently determine the amount of protein that is produced. In the immune suppressive environments of tumours, T cells gradually lose the capacity to produce effector molecules, resulting in tumour immune escape. Recently, the role of post-transcriptional regulation in fine-tuning T-cell effector function has become more appreciated. Furthermore, several groups have shown that exhausted or dysfunctional T cells from cancer patients or murine models possess mRNA for inflammatory mediators, but fail to produce effector molecules, hinting that post-transcriptional events also play a role in hampering tumour-infiltrating lymphocyte effector function. Here, the post-transcriptional regulatory events governing T-cell cytokine production are reviewed, with a specific focus on the importance of post-transcriptional regulation in anti-tumour responses. Furthermore, potential approaches to circumvent tumour-mediated dampening of T-cell effector function through the (dis)engagement of post-transcriptional events are explored, such as CRISPR/Cas9-mediated genome editing or chimeric antigen receptors.

Various skin manifestations related to inflammatory bowel disease: A nationwide cross-sectional study on the Korean population

Inflammatory bowel disease (IBD) presents with various extraintestinal manifestations. As part of them, various skin diseases are suggested to be related to IBD. We aimed to identify the epidemiology and risk of developing skin manifestations in patients with IBD. We used Korean insurance claims data and selected patients with IBD and age/sex-matched non-IBD subjects between 2013 and 2017 using the diagnosis code and prescription records of IBD-specific medications. The prevalence and risk of concurrent skin diseases were estimated. We identified 64 837 patients with IBD. Reactive skin eruptions including pyoderma gangrenosum and erythema nodosum were associated with IBD with highest odds ratios among three categories of reactive, inflammatory, and autoimmune skin diseases. Inflammatory skin diseases including rosacea, psoriasis, atopic dermatitis, hidradenitis suppurativa, and acne conglobata were significantly associated with IBD, but the association was less marked compared to reactive skin eruptions. The patients with IBD also had a higher risk of autoimmune skin diseases including vitiligo and alopecia areata than non-IBD subjects. We determined that IBD was related to various skin diseases including reactive, inflammatory, and autoimmune skin diseases. Considering these relationships can allow better management of patients with IBD and comorbid skin diseases.

Inflammatory Responses of Porcine MoDC and Intestinal Epithelial Cells in a Direct-Contact Co-culture System Following a Bacterial Challenge

Intestinal epithelial cells (IEC) and immune cells, such as dendritic cells (DC), jointly control the immune response towards luminal pathogens in the intestinal mucosa. Crosstalk between IEC and DC is crucial for coordinating immune responses and occurs via soluble factors and direct cell-cell contacts. The present study aimed at establishing a direct-contact co-culture model of porcine IEC and DC to mimic these interactions. The effects of (1) co-cultivation of the two cell types and (2) bacterial infection on the inflammatory response patterns of each of the cell types were determined with a special focus on the canonical and non-canonical inflammasome signaling pathways. In infection experiments, in vitro cultures were exposed to either the probiotic Enterococcus (E.) faecium NCIMB 10415 or enterotoxigenic Escherichia coli (ETEC). In porcine IEC (IPEC-J2), co-cultivation with porcine monocyte-derived DC (MoDC) resulted in reduced basal NLRP3 (nucleotide oligomerization domain [NOD]-like receptor [NLR] family, pyrin domain containing 3) inflammasome mRNA levels in unstimulated conditions. In porcine MoDC, the presence of IPEC-J2 cells evoked a noticeable decrease of interleukin (IL)-8 and transforming growth factor-β (TGF-β) mRNA and protein expression. ETEC, in contrast to E. faecium, modulated the inflammasome pathway in IPEC-J2 cells and porcine MoDC. Co-cultured IPEC-J2 cells showed an augmented inflammasome response to ETEC infection. By contrast, MoDC revealed a weakened ETEC response under such co-culture conditions as indicated by a reduction of inflammasome-related IL-1β protein release. Our data indicate that the close contact between IEC and resident immune cells has a major effect on their immunological behavior.

Idebenone Protects against Spontaneous Chronic Murine Colitis by Alleviating Endoplasmic Reticulum Stress and Inflammatory Response

Endoplasmic reticulum (ER) stress in intestinal secretory goblet cells has been linked to the development of ulcerative colitis (UC). Emerging evidence suggests that the short chain quinone drug idebenone displays anti-inflammatory activity in addition to its potent antioxidant and mitochondrial electron donor properties. This study evaluated the impact of idebenone in Winnie mice, that are characterized by spontaneous chronic intestinal inflammation and ER stress caused by a missense mutation in the mucin MUC2 gene. Idebenone (200 mg/kg) was orally administered daily to 5-6 weeks old Winnie mice over a period of 21 days. Idebenone treatment substantially improved body weight gain, disease activity index (DAI), colon length and histopathology score. Immunohistochemistry revealed increased expression of MUC2 protein in goblet cells, consistent with increased MUC2 mRNA levels. Furthermore, idebenone significantly reduced the expression of the ER stress markers C/EBP homologous protein (CHOP), activating transcription factor 6 (ATF6) and X-box binding protein-1 (XBP-1) at both mRNA and protein levels. Idebenone also effectively reduced pro-inflammatory cytokine levels in colonic explants. Taken together, these results indicate that idebenone could represent a potential therapeutic approach against human UC by its strong anti-inflammatory activity and its ability to reduce markers of ER stress.

Advanced In Vitro Testing Strategies and Models of the Intestine for Nanosafety Research

There is growing concern about the potential adverse effects of oral exposure to engineered nanomaterials (ENM). Recent years have witnessed major developments in and advancement of intestinal in vitro models for nanosafety evaluation. The present paper reviews the key factors that should be considered for inclusion in nonanimal alternative testing approaches to reliably reflect the in vivo dynamics of the physicochemical properties of ENM as well the intestinal physiology and morphology. Currently available models range from simple cell line-based monocultures to advanced 3D systems and organoids. In addition, in vitro approaches exist to replicate the mucous barrier, digestive processes, luminal flow, peristalsis, and interactions of ENM with the intestinal microbiota. However, while the inclusion of a multitude of individual factors/components of particle (pre)treatment, exposure approach, and cell model approximates in vivo-like conditions, such increasing complexity inevitably affects the system's robustness and reproducibility. The selection of the individual modules to build the in vitro testing strategy should be driven and justified by the specific purpose of the study and, not least, the intended or actual application of the investigated ENM. Studies that address health hazards of ingested ENM likely require different approaches than research efforts to unravel the fundamental interactions or toxicity mechanisms of ENM in the intestine. Advanced reliable and robust in vitro models of the intestine, especially when combined in an integrated testing approach, offer great potential to further improve the field of nanosafety research.

The anti-inflammatory activity of peptides from simulated gastrointestinal digestion of preserved egg white in DSS-induced mouse colitis

Peptides DEDTQAMPFR (DR-10), MLGATSL (ML-7), SLSFASR (SR-7), and MSYSAGF (MF-7) derived from simulated gastrointestinal digestion of preserved egg white (SGD-PEW) exerted anti-inflammatory effects on Caco-2 cells. Here, we aimed to evaluate the anti-inflammatory effects of these peptides derived from SGD-PEW in a mouse model of dextran sodium sulfate (DSS)-induced colitis. The results showed that DR-10, ML-7, SR-7 and MF-7 significantly ameliorated the clinical symptoms of DSS-induced mice colitis, such as weight loss, disease activity index (DAI), colon shortening, spleen hypertrophy and histological scores. Treatment with DR-10, ML-7, SR-7 and MF-7 also significantly inhibited the local secretion of pro-inflammatory cytokines TNF-α and IL-6 and markedly decreased the gene expression of pro-inflammatory cytokines, including TNF-α, IL-6, IL-17, IL-1β, IFN-γ and MCP-1, in DSS-induced mice colitis. Overall, MF-7 showed the best effect of alleviating DSS-induced colitis among the four peptides. These results suggested that MF-7, DR-10, ML-7 and SR-7 may be a potential promising candidate for the treatment of inflammatory bowel disease (IBD).

Innate Lymphoid Cells: A Link between the Nervous System and Microbiota in Intestinal Networks

Innate lymphoid cells (ILCs) are a novel family of innate immune cells that act as key coordinators of intestinal mucosal surface immune defense and are essential for maintaining intestinal homeostasis and barrier integrity by responding to locally produced effector cytokines or direct recognition of exogenous or endogenous danger patterns. ILCs are also involved in the pathogenesis of inflammatory bowel disease (IBD). Many studies have demonstrated the occurrence of crosstalk between ILCs and intestinal microbiota, and ILCs have recently been shown to be connected to the enteric nervous system (ENS). Thus, ILCs may act as a key link between the nervous system and microbiota in intestinal networks. In this review, we briefly summarize the role of the ILCs in the intestinal tract (particularly in the context of IBD) and discuss the relationship between ILCs and the microbiota/ENS.

Temporal clinical, proteomic, histological and cellular immune responses of dextran sulfate sodium-induced acute colitis

AIM

To investigate the temporal clinical, proteomic, histological and cellular immune profiles of dextran sulfate sodium (DSS)-induced acute colitis.

METHODS

Acute colitis was induced in C57Bl/6 female mice by administration of 1%, 2% or 3% DSS in drinking water for 7 d. Animals were monitored daily for weight loss, stool consistency and blood in the stool, while spleens and colons were harvested on day 8. A time course analysis was performed in mice ingesting 3% DSS, which included colon proteomics through multiplex assay, colon histological scoring by a blinded investigator, and immune response through flow cytometry or immunohistochemistry of the spleen, mesenteric lymph node and colon.

RESULTS

Progressive worsening of clinical colitis was observed with increasing DSS from 1% to 3%. In mice ingesting 3% DSS, colon shortening and increase in pro-inflammatory factors starting at day 3 was observed, with increased spleen weights at day 6 and day 8. This coincided with cellular infiltration in the colon from day 2 to day 8, with progressive accumulation of macrophages F4/80⁺, T helper CD4⁺ (Th), T cytotoxic CD8⁺ (Tcyt) and T regulatory CD25⁺ (Treg) cells, and progressive changes in colonic pathology including destruction of crypts, loss of goblet cells and depletion of the epithelial barrier. Starting on day 4, mesenteric lymph node and/or spleen presented with lower levels of Treg, Th and Tcyt cells, suggesting an immune cell tropism to the gut.

CONCLUSION

These results demonstrate that the severity of experimental colitis is dependent on DSS concentration, correlated with clinical, proteomic, histological and cellular immune response on 3% DSS.

Oxidative Stress and Effect of Treatment on the Oxidation Product Decomposition Processes in IBD

Oxidative stress plays an important role in IBD because chronic intestinal inflammation is associated with the overproduction of reactive oxygen species (ROS) leading to oxidative stress, which has been implicated in IBD. Many lines of evidence suggest that IBD is associated with an imbalance between ROS and antioxidant activity which generates oxidative stress as the result of either ROS overproduction or a decrease in antioxidant activity. Our study was to evaluate the influence of oxidative stress and antioxidants on the course of the disease and treatment of IBD patients. Our results show that an increase of LOOH levels positively correlates with an increase in MDA levels; therefore, MDA may be a marker indicating lipid peroxidation. Also, being the decomposition product of oxidation processes, MDA may be applied as a useful biomarker for identifying the effect of endogenous oxidative stress in Crohn's disease patients. The anti-inflammatory efficacy of AZA drugs may be the result of a reduction of the amount of lipid peroxides in the intestinal mucosa cells in CD patients and facilitate mucosal healing.

Anti-NKG2D mAb: A New Treatment for Crohn's Disease?

Crohn’s disease (CD) and ulcerative colitis (UC) are immunologically-mediated, debilitating conditions resulting from destructive inflammation of the gastrointestinal tract. The pathogenesis of IBD is incompletely understood, but is considered to be the result of an abnormal immune response with a wide range of cell types and proteins involved. Natural Killer Group 2D (NKG2D) is an activating receptor constitutively expressed on human Natural Killer (NK), γδ T, mucosal-associated invariant T (MAIT), CD56⁺ T, and CD8⁺ T cells. Activation of NKG2D triggers cellular proliferation, cytokine production, and target cell killing. Research into the NKG2D mechanism of action has primarily been focused on cancer and viral infections where cytotoxicity evasion is a concern. In human inflammatory bowel disease (IBD) this system is less characterized, but the ligands have been shown to be highly expressed during intestinal inflammation and the following receptor activation may contribute to tissue degeneration. A recent phase II clinical trial showed that an antibody against NKG2D induced clinical remission of CD in some patients, suggesting NKG2D and its ligands to be of importance in the pathogenesis of CD. This review will describe the receptor and its ligands in intestinal tissues and the clinical potential of blocking NKG2D in Crohn’s disease.

Development of an in vitro co-culture model to mimic the human intestine in healthy and diseased state

The intestine forms the largest interface between the environment and the human organism. Its integrity and functioning are crucial for the uptake of nutrients while preventing access of harmful antigens. Inflammatory conditions can significantly change the normal functioning of the intestine. In vitro models that adequately reproduce both healthy and inflamed intestinal tissue could provide a useful tool for studying the mechanisms of intestinal inflammation and investigating new therapeutic drugs.

We established a co-culture of Caco-2 and PMA-differentiated THP-1 cells that mimics the intestine in healthy and controlled inflamed states. In homoeostatic conditions without stimulation, Caco-2 and THP-1 cells were co-cultured for 48 h without affecting the barrier integrity and with no increase in the release of cytokines, nitric oxide or lactate dehydrogenase. To simulate the inflamed intestine, the Caco-2 barrier was primed with IFN-γ and THP-1 cells were pre-stimulated with LPS and IFN-γ. In these conditions a significant but temporary reduction in barrier integrity was measured, and large concentrations of pro-inflammatory cytokines and cytotoxicity markers detected.

With its ability to feature numerous hallmarks of intestinal inflammation the presented co-culture model of epithelial cells and macrophages offers a unique possibility to study exposure effects in relation to the health status of the intestine.

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A novel, tunable co-culture model of Caco-2 and THP-1 cells was established.

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The THP-1 differentiation protocol is crucial for a stable co-culture with Caco-2.

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Synergistic effects of TNF-α and IFN-γ were key to induce inflammation in vitro.

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The inflamed co-culture shows barrier disruption, cytokine release and cytotoxicity.

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Downregulation of inflammation is prevented by pretreatment of cells with cytokines.

Decreased CD8+CD28+/CD8+CD28- T cell ratio can sensitively predict poor outcome for patients with complicated Crohn disease

Crohn disease (CD) with complications such as penetrating, stricturing, and perianal disease is called complicated CD. The aim of this study is to test the efficiency with which the CD8CD28/CD8CD28 cell balance can predict a subsequent active stage in patients with newly diagnosed complicated CD.Seventeen patients with complicated CD and 48 CD patients with no complications were enrolled. Blood CD8 T cells were tested from all of the 65 newly diagnosed CD patients upon enrollment. The potential risk factors were compared between the 2 groups. A 30-week follow-up was performed, and the efficiency of the CD8 cell balance at predicting active CD was analyzed using receiver-operating characteristic curves. The cumulative remission lasting rates (CRLRs) were analyzed using the Kaplan-Meier method.Compared with the control CD group, patients with complicated CD were predominantly male and younger in age; they also had lower body mass indices (BMIs), higher Crohn disease activity indices (CDAIs), higher immunosuppressant and steroid prescription rates, and significantly higher surgical rates. The CD8CD28/CD8CD28 balance was associated with BMI, CDAI, steroids, and surgery. The CD8CD28/CD8CD28 ratios were significantly lower at week 0 and on the 6th, 22nd, and 30th week during follow-up with a shorter lasting time of remission for the complicated CD patients. The CD8CD28/CD8CD28 ratio could accurately predict the active stage for the patients with complicated CD, and the highest sensitivity (89.2%) and specificity (85.3%) were found when the ratio was 1.03. Treatment with steroids and surgery, along with a significantly lower CD8CD28/CD8CD28 ratio and lower CRLRs, was closely related to a worse outcome for the patients with complicated CD.Patients requiring steroids and surgery experience more severe disease activity and thus a disequilibrated immunological balance, which could be the main reason for a decreased CD8CD28/CD8CD28 ratio. This ratio can sensitively predict the active stage for patients with complicated CD, and more care should be taken when this ratio is <1.03.

Novel Insights into the Mechanisms of Gut Homing and Antiadhesion Therapies in Inflammatory Bowel Diseases

Therapeutic compounds interfering with T cell trafficking are a new column of inflammatory bowel disease (IBD) treatment. Currently, the anti-α4β7 integrin antibody vedolizumab is successfully used in the clinic and further drugs are likely to follow. Despite these clinical advances, the precise mechanistic background of their action is only gradually elucidated and still a matter of intensive research. Only recently, advances made with the help of new in vivo models and human studies have contributed to shape our concept of T cell trafficking in IBD by deciphering some important and so far unanswered questions. At the same time, basic and clinical data have generated new issues to be addressed on the way toward a clear perception of trafficking mechanisms and toward elucidation of the action of compounds interfering with this process. In this review, we will give a comprehensive outline of all components of T cell trafficking in regard to IBD before discussing the current knowledge concerning targeted interference with integrins in this complex network. Moreover, we will summarize remaining ambiguity and give an outlook on potential future targets.

A primary human macrophage-enteroid co-culture model to investigate mucosal gut physiology and host-pathogen interactions

Integration of the intestinal epithelium and the mucosal immune system is critical for gut homeostasis. The intestinal epithelium is a functional barrier that secludes luminal content, senses changes in the gut microenvironment, and releases immune regulators that signal underlying immune cells. However, interactions between epithelial and innate immune cells to maintain barrier integrity and prevent infection are complex and poorly understood. We developed and characterized a primary human macrophage-enteroid co-culture model for in-depth studies of epithelial and macrophage interactions. Human intestinal stem cell-derived enteroid monolayers co-cultured with human monocyte-derived macrophages were used to evaluate barrier function, cytokine secretion, and protein expression under basal conditions and following bacterial infection. Macrophages enhanced barrier function and maturity of enteroid monolayers as indicated by increased transepithelial electrical resistance and cell height. Communication between the epithelium and macrophages was demonstrated through morphological changes and cytokine production. Intraepithelial macrophage projections, efficient phagocytosis, and stabilized enteroid barrier function revealed a coordinated response to enterotoxigenic and enteropathogenic E. coli infections. In summary, we have established the first primary human macrophage-enteroid co-culture system, defined conditions that allow for a practical and reproducible culture model, and demonstrated its suitability to study gut physiology and host responses to enteric pathogens.

Colonic and Hepatic Modulation by Lipoic Acid and/or N-Acetylcysteine Supplementation in Mild Ulcerative Colitis Induced by Dextran Sodium Sulfate in Rats

Lipoic acid (LA) and N-acetylcysteine (NAC) are antioxidant and anti-inflammatory agents that have not yet been tested on mild ulcerative colitis (UC). This study aims to evaluate the action of LA and/or NAC, on oxidative stress and inflammation markers in colonic and hepatic rat tissues with mild UC, induced by dextran sodium sulfate (DSS) (2% w/v). LA and/or NAC (100 mg·kg·day^-1, each) were given, once a day, in the diet, in a pretreatment phase (7 days) and during UC induction (5 days). Colitis induction was confirmed by histological and biochemical analyses (high performance liquid chromatography, spectrophotometry, and Multiplex®). A redox imbalance occurred before an immunological disruption in the colon. NAC led to a decrease in hydrogen peroxide (H₂O₂), malondialdehyde (MDA) levels, and myeloperoxidase activity. In the liver, DSS did not cause damage but treatments with both antioxidants were potentially harmful, with LA increasing MDA and LA + NAC increasing H₂O₂, tumor necrosis factor alpha, interferon gamma, and transaminases. In summary, NAC exhibited the highest colonic antioxidant and anti-inflammatory activity, while LA + NAC caused hepatic damage.

A 3D co-culture of three human cell lines to model the inflamed intestinal mucosa for safety testing of nanomaterials

Oral exposure to nanomaterials is a current concern, asking for innovative biological test systems to assess their safety, especially also in conditions of inflammatory disorders. Aim of this study was to develop a 3D intestinal model, consisting of Caco-2 cells and two human immune cell lines, suitable to assess nanomaterial toxicity, in either healthy or diseased conditions. Human macrophages (THP-1) and human dendritic cells (MUTZ-3) were embedded in a collagen scaffold and seeded on the apical side of transwell inserts. Caco-2 cells were seeded on top of this layer, forming a 3D model of the intestinal mucosa. Toxicity of engineered nanoparticles (NM101 TiO2, NM300 Ag, Au) was evaluated in non-inflamed and inflamed co-cultures, and also compared to non-inflamed Caco-2 monocultures. Inflammation was elicited by IL-1β, and interactions with engineered NPs were addressed by different endpoints. The 3D co-culture showed well preserved ultrastructure and significant barrier properties. Ag NPs were found to be more toxic than TiO2 or Au NPs. But once inflamed with IL-1β, the co-cultures released higher amounts of IL-8 compared to Caco-2 monocultures. However, the cytotoxicity of Ag NPs was higher in Caco-2 monocultures than in 3D co-cultures. The naturally higher IL-8 production in the co-cultures was enhanced even further by the Ag NPs. This study shows that it is possible to mimic inflamed conditions in a 3D co-culture model of the intestinal mucosa. The fact that it is based on three easily available human cell lines makes this model valuable to study the safety of nanomaterials in the context of inflammation.

Experimental colitis is associated with transcriptional inhibition of Na+/Ca2+ exchanger isoform 1 (NCX1) expression by interferon γ in the renal distal convoluted tubules

NCX1 is a Na(+)/Ca(2+) exchanger, which is believed to provide a key route for basolateral Ca(2+) efflux in the renal epithelia, thus contributing to renal Ca(2+) reabsorption. Altered mineral homeostasis, including intestinal and renal Ca(2+) transport may represent a significant component of the pathophysiology of the bone mineral density loss associated with Inflammatory Bowel Diseases (IBD). The objective of our research was to investigate the effects of TNBS and DSS colitis and related inflammatory mediators on renal Ncx1 expression. Colitis was associated with decreased renal Ncx1 expression, as examined by real-time RT-PCR, Western blotting, and immunofluorescence. In mIMCD3 cells, IFNγ significantly reduced Ncx1 mRNA and protein expression. Similar effects were observed in cells transiently transfected with a reporter construct bearing the promoter region of the kidney-specific Ncx1 gene. This inhibitory effect of IFNγ is mediated by STAT1 recruitment to the proximal promoter region of Ncx1. Further in vivo study with Stat1(-/-) mice confirmed that STAT1 is indeed required for the IFNγ mediated Ncx1 gene regulation. These results strongly support the hypothesis that impaired renal Ca(2+) handling occurs in experimental colitis. Negative regulation of NCX1- mediated renal Ca(2+) absorption by IFNγ may significantly contribute to the altered Ca(2+) homeostasis in IBD patients and to IBD-associated loss of bone mineral density.

A method for high purity intestinal epithelial cell culture from adult human and murine tissues for the investigation of innate immune function

Intestinal epithelial cells (IECs) serve as an important physiologic barrier between environmental antigens and the host intestinal immune system. Thus, IECs serve as a first line of defense and may act as sentinel cells during inflammatory insults. Despite recent renewed interest in IEC contributions to host immune function, the study of primary IEC has been hindered by lack of a robust culture technique, particularly for small intestinal and adult tissues. Here, a novel adaptation for culture of primary IEC is described for human duodenal organ donor tissue as well as duodenum and colon of adult mice. These epithelial cell cultures display characteristic phenotypes and are of high purity. In addition, the innate immune function of human primary IEC, specifically with regard to Toll-like receptor (TLR) expression and microbial ligand responsiveness, is contrasted with a commonly used intestinal epithelial cell line (HT-29). Specifically, TLR expression at the mRNA level and production of cytokine (IFNγ and TNFα) in response to TLR agonist stimulation is assessed. Differential expression of TLRs as well as innate immune responses to ligand stimulation is observed in human-derived cultures compared to that of HT-29. Thus, use of this adapted method to culture primary epithelial cells from adult human donors and from adult mice will allow for more appropriate studies of IECs as innate immune effectors.

Molecular control of Tfh-cell differentiation by Roquin family proteins

Post-transcriptional gene regulation by RNA-binding proteins is a fast and effective way to adapt gene expression and change cellular responses. These trans-acting factors have been involved in a number of cell fate decisions, and their mutation is often associated with the development of disease. The RNA-binding protein Roquin-1 has been found to be crucial in the maintenance of peripheral tolerance and the prevention of autoimmune disease. This review describes the molecular role of Roquin family proteins in the control of follicular T-helper cell differentiation. Here, we discuss the redundant regulation of Icos and Ox40 costimulatory receptor mRNAs by Roquin-1 and Roquin-2 proteins. A major focus is placed on the distinct activity of Roquin-1 or Roquin-2 proteins in the mouse models of conditional gene targeting. These recent data are then integrated into an interpretation of altered Roquin protein function in the sanroque mouse that expresses the Roquin-1 protein with just one amino acid substitution and, different from the Roquin-1-deficient mouse, develops lupus-like autoimmune disease.

Hypoxia and Integrin-Mediated Epithelial Restitution during Mucosal Inflammation

Epithelial damage and loss of intestinal barrier function are hallmark pathologies of the mucosal inflammation associated with conditions such as inflammatory bowel disease. In order to resolve inflammation and restore intestinal integrity the mucosa must rapidly and effectively repair the epithelial barrier. Epithelial wound healing is a highly complex and co-ordinated process and the factors involved in initiating intestinal epithelial healing are poorly defined. In order for restitution to be successful there must be a balance between epithelial cell migration, proliferation, and differentiation within and adjacent to the inflamed area. Endogenous, compensatory epithelial signaling pathways are activated by the changes in oxygen tensions that accompany inflammation. These signaling pathways induce the activation of key transcription factors, governing anti-apoptotic, and proliferative processes resulting in epithelial cell survival, proliferation, and differentiation at the site of mucosal inflammation. In this review, we will discuss the primary processes involved in epithelial restitution with a focus on the role of hypoxia-inducible factor and epithelial integrins as mediators of epithelial repair following inflammatory injury at the mucosal surface.

Inflammatory bowel diseases influence major histocompatibility complex class I (MHC I) and II compartments in intestinal epithelial cells

Antigen presentation by intestinal epithelial cells (IEC) is crucial for intestinal homeostasis. Disturbances of major histocompatibility complex class I (MHC I)- and II-related presentation pathways in IEC appear to be involved in an altered activation of CD4(+) and CD8(+) T cells in inflammatory bowel disease. However, a comprehensive analysis of MHC I- and II-enriched compartments in IEC of the small and large bowel in the healthy state as opposed to inflammatory bowel diseases is lacking. The aim of this study was to characterize the subcellular expression of MHC I and II in the endocytic pathway of IEC throughout all parts of the intestinal tract, and to identify differences between the healthy state and inflammatory bowel diseases. Biopsies were taken by endoscopy from the duodenum, jejunum, ileum and colon in healthy individuals (n = 20). In Crohn's disease (CD), biopsies were obtained from the ileum and colon and within the colon from ulcerative colitis (UC) patients (n = 15). Analysis of IEC was performed by immunoelectron microscopy. MHC I and II were identified in early endosomes and multi-vesicular, multi-lamellar, electrondense and vacuolar late endosomes. Both molecules were enriched in multi-vesicular bodies. No differences were found between the distinct parts of the gut axis. In CD and UC the expression of MHC I and II showed a shift from multi-vesicular bodies towards the basolateral membranes. Within the multi-vesicular bodies, MHC I and II moved from internal vesicles to the limiting membranes upon inflammation in CD and UC. MHC I- and II-enriched compartments in IEC were identical in all parts of the small and large bowel. CD and UC appear to modulate the MHC I- and II-related presentation pathways of exogenous antigens in IEC.

Aberrant expression of circulating Th17, Th1 and Tc1 cells in patients with active and inactive ulcerative colitis

Ulcerative colitis (UC) is a chronic relapsing inflammatory bowel disease, yet its etiology and pathogenesis remain poorly understood. The aberrant expression of T lymphocytes plays an essential role in the progression of UC. This study aimed to evaluate the expression profile of circulating Th17, Th1 and Tc1 cells in patients with active and inactive UC. Our results revealed that the percentage of circulating Th17 cells (CD3+CD8-IL-17+) was significantly increased in patients with active UC when compared with the percentage in patients with inactive UC, Crohn's disease (CD) and healthy controls. The percentages of circulating Th1 (CD3+CD8-IFN-γ+) and Tc1 (CD3+CD8+IFN-γ+) cells were also higher in patients with active UC when compared with the percentages in patients with inactive UC and normal controls, although levels were lower than that in CD. Further analysis showed that Th17 cells were positively correlated with Th1 cells, but not with Tc1 cells. Notably, the three cells had a positive correlation with disease activity, extent of disease, detection of erythrocyte sedimentation rate and c-reactive protein in active UC. Moreover, plasma IL-17 was higher in patients with active UC, and a similar trend applied to the mRNA levels of RORγt and T-bet in peripheral blood mononuclear cells (PBMCs). The levels of p-STAT3 and p-STAT5 in PBMCs, as well as the ratio of p-STAT3/p-STAT5, were also elevated in active UC patients. Taken together, our findings revealed that elevated circulating Th17, Th1 and Tc1 cells and the aberrant activation of the STAT pathway may be implicated in the progression of UC. These findings may provide preliminary experimental clues for the development of new therapies for UC.

NutriChip: nutrition analysis meets microfluidics

This focus article introduces the concept of NutriChip, an integrated microfluidic platform for investigating the potential of the immuno-modulatory function of dairy food. The core component of the NutriChip is a miniaturized artificial human gastrointestinal tract (GIT), which consists of a confluent layer of epithelial cells separated from a co-culture of immune cells by a permeable membrane. This setting creates conditions mimicking the human GIT and allows studying processes that characterize the passage of nutrients though the human GIT, including the activation of immune cells in response to the transfer of nutrients across the epithelial layer. The NutriChip project started by developing a biologically active in vitro cellular system in a commercial Transwell co-culture system. This Transwell system serves as a reference for the micro-scale device which is being developed. The microfluidic setup of NutriChip allows monitoring of the response of immune cells to pro-inflammatory stimuli, such as lipid polysaccharide (LPS), and to the application of potentially anti-inflammatory dairy food. This differential response will be quantified by measuring the variation in expression of pro-inflammatory cytokines, including interleukin 1 (IL-1) and interleukin 6 (IL-6), secreted by the immune cells, and this is achieved by using a dedicated optical imager. A series of dairy products will be screened for their anti-inflammatory properties using the NutriChip system and, finally, the outcome of the NutriChip will be validated by a human nutrition trial. Therefore, the NutriChip platform offers a new option to evaluate the influence of food quality on health, by monitoring the expression of relevant immune cell biomarkers.

A three-dimensional coculture of enterocytes, monocytes and dendritic cells to model inflamed intestinal mucosa in vitro

While epithelial cell culture models (e.g., Caco-2 cell line) are widely used to assess the absorption of drug molecules across healthy intestinal mucosa, there are no suitable in vitro models of the intestinal barrier in the state of inflammation. Thus development of novel drugs and formulations for the treatment of inflammatory bowel disease is largely bound to animal models. We here report on the development of a complex in vitro model of the inflamed intestinal mucosa, starting with the selection of suitable enterocyte cell line and proinflammatory stimulus and progressing to the setup and characterization of a three-dimensional coculture of human intestinal epithelial cells and immunocompetent macrophages and dendritic cells. In the 3D setup, controlled inflammation can be induced allowing the mimicking of pathophysiological changes occurring in vivo in the inflamed intestine. Different combinations of proinflammatory stimuli (lipopolysaccharides from Escherichia coli and Salmonella typhimurium, interleukin-1β, interferon-γ) and intestinal epithelial cell lines (Caco-2, HT-29, T84) were evaluated, and only Caco-2 cells were responsive to stimulation, with interleukin-1β being the strongest stimulator. Caco-2 cells responded to the proinflammatory stimulus with a moderate upregulation of proinflammatory markers and a slight, but significant, decrease (20%) of transepithelial electrical resistance (TEER) indicating changes in the epithelial barrier properties. Setting up the coculture model, macrophages and dendritic cells derived from periphery blood monocytes were embedded in a collagen layer on a Transwell filter insert and Caco-2 cells were seeded atop. Even in the presence of immunocompetent cells Caco-2 cells formed a tight monolayer. Addition of IL-1β increased inflammatory cytokine response more strongly compared to Caco-2 single culture and stimulated immunocompetent cells proved to be highly active in sampling apically applied nanoparticles. Thus the 3D coculture provides additional complexity and information compared to the stimulated single cell model. The coculture system may serve as a valuable tool for developing drugs and formulations for the treatment of inflammatory bowel diseases, as well as for studying the interaction of xenobiotics and nanoparticles with the intestinal epithelial barrier in the state of inflammation.

Mucosal biomarkers in inflammatory bowel disease: Key pathogenic players or disease predictors?

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders of the bowel, including ulcerative colitis and Crohn’s disease. A single etiology has not been identified, but rather the pathogenesis of IBD is very complex and involves several major and minor contributors, employing different inflammatory pathways which have different roles in different patients. Although new and powerful medical treatments are available, many are biological drugs or immunosuppressants, which are associated with significant side effects and elevated costs. As a result, the need for predicting disease course and response to therapy is essential. Major attempts have been made at identifying clinical characteristics, concurrent medical therapy, and serological and genetic markers as predictors of response to biological agents. Only few reports exist on how mucosal/tissue markers are able to predict clinical behavior of the disease or its response to therapy. The aim of this paper therefore is to review the little information available regarding tissue markers as predictors of response to therapy, and reevaluate the role of tissue factors associated with disease severity, which can eventually be ranked as “tissue factor predictors”. Five main categories are assessed, including mucosal cytokines and chemokines, adhesion molecules and markers of activation, immune and non-immune cells, and other mucosal components. Improvement in the design and specificity of clinical studies are mandatory to be able to classify tissue markers as predictors of disease course and response to specific therapy, obtain the goal of achieving “personalized pathogenesis-oriented therapy” in IBD.

Genetic risk factors for post-infectious irritable bowel syndrome following a waterborne outbreak of gastroenteritis

BACKGROUND & AIMS

Acute gastroenteritis is the strongest risk factor for irritable bowel syndrome (IBS). In May 2000, >2300 residents of Walkerton, Ontario, developed gastroenteritis from microbial contamination of the municipal water supply; a longitudinal study found that >36.2% of these developed IBS. We used this cohort to study genetic susceptibility to post-infectious (PI)-IBS.

METHODS

We screened 79 functional variants of genes with products involved in serotoninergic pathways, intestinal epithelial barrier function, and innate immunity and performed fine mapping in regions of interest. We compared data from Walkerton residents who developed gastroenteritis and reported PI-IBS 2 to 3 years after the outbreak (n = 228, cases) with data from residents who developed gastroenteritis but did not develop PI-IBS (n = 581, controls).

RESULTS

Four variants were associated with PI-IBS, although the association was not significant after correction for the total number of single nucleotide polymorphisms. Two were located in TLR9, which encodes a pattern recognition receptor (rs352139, P545P; P = .0059 and rs5743836, -T1237C; P = .0250; r(2) < 0.14); 1 was in CDH1, which encodes a tight junction protein (rs16260, -C160A; P = .0352); and 1 was in IL6, which encodes a cytokine (rs1800795, -G174C; P = .0420). Denser mapping of these 3 regions revealed 1 novel association in IL6 (rs2069861; P = .0069) and 14 associations that could be accounted for by linkage disequilibrium with the 4 original variants. The TLR9, IL6, and CDH1 variants all persisted as independent risk factors for PI-IBS when controlling for previously identified clinical risk factors.

CONCLUSION

This is the first descriptive study to assess potential genetic determinants of PI-IBS. Genes that encode proteins involved in epithelial cell barrier function and the innate immune response to enteric bacteria are associated with development of IBS following acute gastroenteritis.

The CD40-CD40L pathway contributes to the proinflammatory function of intestinal epithelial cells in inflammatory bowel disease

In inflammatory bowel diseases (IBD), intestinal epithelial cells (IECs) are involved in the outbalanced immune responses toward luminal antigens. However, the signals responsible for this proinflammatory capacity of IECs in IBD remain unclear. The CD40/CD40L interaction activates various pathways in immune and nonimmune cells related to inflammation and was shown to be critical for the development of IBD. Here we demonstrate CD40 expression within IECs during active IBD. Endoscopically obtained biopsies taken from Crohn's disease (n = 112) and ulcerative colitis patients (n = 67) consistently showed immunofluorescence staining for CD40 in IECs of inflamed ileal or colonic mucosa. In noninvolved mucosa during active disease, tissue obtained during Crohn's disease or ulcerative colitis in remission and biopsies from healthy controls (n = 38) IECs almost entirely lacked CD40 staining. Flow cytometry and RT-PCR analysis using different intestinal epithelial cell lines (HT29, SW480, and T84) showed IFN-gamma to effectively induce CD40 in IECs. Cells were virtually unresponsive to LPS or whole E. coli regarding CD40 expression. In addition, a moderate induction of CD40 was found in response to TNF-alpha, which exerted synergistical effects with IFN-gamma. CD40 ligation by CD40L-transfected murine fibroblasts or soluble CD40L increased the secretion of IL-8 in IFN-gamma pretreated HT29 cells. Our findings provide evidence for the epithelial expression and modulation of CD40 in IBD-affected mucosa and indicate its involvement in the proinflammatory function of IECs.

A novel mTOR inhibitor is efficacious in a murine model of colitis

Ulcerative colitis is an autoimmune-inflammatory disease characterized by increased proliferation of colonic epithelial cells, dysregulation of signal transduction pathways, elevated mucosal T cell activation, increased production of proinflammatory cytokines, and enhanced leukocyte infiltration into colonic interstitium. Several compounds that possess antiproliferative properties and/or inhibit cytokine production exhibit a therapeutic effect in murine models of colitis. Mammalian target of rapamycin (mTOR), a protein kinase regulating cell proliferation, is implicated in colon carcinogenesis. In this study, we report that a novel haloacyl aminopyridine-based molecule (P2281) is a mTOR inhibitor and is efficacious in a murine model of human colitis. In vitro studies using Western blot analysis and cell-based ELISA assays showed that P2281 inhibits mTOR activity in colon cancer cells. In vitro and in vivo assays of proinflammatory cytokine production revealed that P2281 diminishes induced IFN-gamma production but not TNF-alpha production, indicating preferential inhibitory effects of P2281 on T cell function. In the dextran sulfate sodium (DSS) model of colitis, 1) macroscopic colon observations demonstrated that P2281 significantly inhibited DSS-induced weight loss, improved rectal bleeding index, decreased disease activity index, and reversed DSS-induced shortening of the colon; 2) histological analyses of colonic tissues revealed that P2281 distinctly attenuated DSS-induced edema, prominently diminished the leukocyte infiltration in the colonic mucosa, and resulted in protection against DSS-induced crypt damage; and 3) Western blot analysis showed that P2281 blocks DSS-induced activation of mTOR. Collectively, these results provide direct evidence that P2281, a novel mTOR inhibitor, suppresses DSS-induced colitis by inhibiting T cell function and is a potential therapeutic for colitis. Given that compounds with anticancer activity show promising anti-inflammatory efficacy, our findings reinforce the cross-therapeutic functionality of potential drugs.

Modulation of membrane type 1 matrix metalloproteinase by LPS and gamma interferon bound to extracellular matrix in intestinal crypt cells

Membrane type 1 matrix metalloproteinase (MT1-MMP) is an integral membrane protein that participates in the processing and degradation of cell surface proteins and the extracellular matrix (ECM). This enzyme regulates ECM turnover in wound repair, promotes cell migration and activates other MMPs, such as MMP-2, which is involved in angiogenesis, cell migration and tumoral metastasis. An increase in pro-inflammatory cytokine expression, such as gamma interferon (IFN-gamma), has been associated with chronic wounds in inflammatory bowel diseases. However, the extent to which cytokines modulate MT1-MMP has not been totally defined. In this report, the effects of the bacterial lipopolysaccharide (LPS) and ECM-bound IFN-gamma on MT1-MMP expression and MMP-2 activity were evaluated by Western blot, RT-PCR and zymography in isolated intestinal epithelial and cultured HT-29 cells. In the presence of LPS, ECM-bound IFN-gamma, but not soluble IFN-gamma, reduced the enterocyte MT1-MMP protein expression. In addition, the active form of MMP-2 was also decreased in the presence of both LPS and IFN-gamma, indicating that lower MMP-2 activity accompanied the decrease in MT1-MMP expression. These results suggest the possibility that endotoxin and ECM-bound IFN-gamma may affect matrix remodeling by modulating matrix metalloproteinase in enterocytes during wound healing.

Luminal antigens access late endosomes of intestinal epithelial cells enriched in MHC I and MHC II molecules: in vivo study in Crohn's ileitis

In contrast to healthy conditions, intestinal epithelial cells (IECs) stimulate proinflammatory CD4+ and CD8+ T cells during Crohn's disease (CD). The underlying regulatory mechanisms remain unknown. Here we investigated the epithelial expression of major histocompatibility complex (MHC) I and MHC II and its interference with endocytic pathways, in vivo. During ileoscopy, ovalbumin (OVA) was sprayed onto ileal mucosa of CD patients (ileitis and remission) and controls. The epithelial traffic of OVA and MHC I/II pathways were studied in biopsies using fluorescence and electron microscopy. We found MHC I and MHC II to accumulate within multivesicular late endosomes (MVLE) of IECs. Faint labeling for these molecules was seen in early endosomes and lysosomes. MVLE were entered by OVA 10 min after exposure. Exosomes carrying MHC I, MHC II, and OVA were detected in intercellular spaces of the epithelium. OVA trafficking and labeling patterns for MHC I and MHC II in IECs showed no differences between CD patients and controls. Independent of inflammatory stimuli, MHC I and MHC II pathways intersect MVLE in IECs, which were efficiently targeted by luminal antigens. Similar to MHC II-enriched compartments in professional antigen presenting cells, these MVLE might be critically involved in MHC I- and MHC II-related antigen processing in IECs and the source of epithelial-released exosomes. The access of luminal antigens to MHC I in MVLE might indicate that the presentation of exogenous antigens by IECs must not be restricted to MHC II but might also occur as "cross-presentation" via MHC I to CD8+ T cells.

Characterization of cecal gene expression in a differentially susceptible mouse model of bacterial-induced inflammatory bowel disease

BACKGROUND

A/JCr mice develop typhlitis in response to Helicobacter hepaticus infection, whereas C57BL/6 mice coexist with this bacterium in a "commensal" relationship and do not develop disease even during prolonged colonization.

METHODS

To determine mechanisms that control this balance between responsiveness and nonresponsiveness, the mucosal response of A/JCr and C57BL/6 mice to acute H. hepaticus colonization was evaluated using genome-wide profiling. Transcription levels for a subset of gene discoveries were then evaluated longitudinally by semiquantitative real-time reverse-transcriptase polymerase chain reaction (RT-PCR) to identify changes in gene expression that occur during progression from the acute to chronic phase of colonization. To determine whether chronic mucosal inflammation in A/JCr mice was mediated through a Th1 mechanism, as was inferred from the gene expression data, mice with typhlitis were treated with neutralizing antibody targeting IL-12/23p40 or IFN-gamma and the response to treatment was determined by cecal lesion severity and transcription of disease-related genes.

RESULTS

A/JCr mice had a biphasic expression of proinflammatory genes that corresponded with the acute and chronic phases of disease. In contrast, C57BL/6 mice exhibited a less robust acute transcriptional response that waned by day 30 postinoculation. Sustained upregulation of proinflammatory signals and responsiveness to anti-IL-12/23p40 and anti-IFN-gamma antibody suggests that inflammation in A/JCr mice was mediated through a Th1 mechanism. Prolonged upregulation of SOCS3 during the acute response to colonization suggests that C57BL/6 mice maintain mucosal homeostasis, at least in part by attenuating responsiveness to cytokine signaling.

CONCLUSIONS

Collectively, these findings provide a foundation for understanding the immunological mechanisms that confer resistance or susceptibility to H. hepaticus-induced typhlitis.

Immune activation in patients with irritable bowel syndrome

BACKGROUND AND AIMS

We set out to test the hypothesis that irritable bowel syndrome (IBS) is characterized by an augmented cellular immune response with enhanced production of proinflammatory cytokines. We further aimed to explore whether symptoms and psychiatric comorbidity in IBS are linked to the release of proinflammatory cytokines.

METHODS

We characterized basal and Escherichia coli lipopolysaccharide (LPS)-induced cytokine production in peripheral blood mononuclear cells (PBMCs) from 55 IBS patients (18 mixed-, 17 constipation-, 20 diarrhea-predominant) and 36 healthy controls (HCs). PBMCs were isolated by density gradient centrifugation and cultured for 24 hours with or without (1 ng/mL) LPS. Cytokine production (tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, and IL-6) was measured by enzyme-linked immunosorbent assay. Abdominal symptoms and psychiatric comorbidities were assessed by using the validated Bowel Disease Questionnaire and the Hospital Anxiety and Depression Scale.

RESULTS

IBS patients showed significantly (P < .017) higher baseline TNF-alpha, IL-1beta, IL-6, and LPS-induced IL-6 levels compared with HCs. Analyzing IBS subgroups, all cytokine levels were significantly (P < .05) higher in diarrhea-predominant IBS (D-IBS) patients, whereas constipation-predominant IBS patients showed increased LPS-induced IL-1beta levels compared with HCs. Baseline TNF-alpha and LPS-induced TNF-alpha and IL-6 levels were significantly higher in patients reporting more than 3 bowel movements per day, urgency, watery stools, and pain associated with diarrhea compared with patients without these symptoms (all P < .05). LPS-induced TNF-alpha production was associated significantly (r = 0.59, P < .001) with anxiety in patients with IBS.

CONCLUSIONS

Patients with D-IBS display enhanced proinflammatory cytokine release, and this may be associated with symptoms and anxiety.

Distribution of CD8 T cells and expression of Fas/FasL and Bcl-2/Bax in ulcerative colitis

AIM: To investigate the expression of Fas/FasL and Bcl-2/Bax and distribution of CD8 T cells as well as their correlations in ulcerative colitis (UC).

METHODS: Immunohistochemistry was used to detect the expression of CD8, Bcl-2/Bax and Fas/FasL in intestinal mucosal tissues from UC (n = 60) and normal controls (n = 60).

RESULTS: The positive rate of CD8 was significantly higher in the epithelia of UC tissues than that in the controls (52% vs 78%, P < 0.01), and rate in the active UC was also significantly lower than that in the remissive UC (20% vs 74%, P < 0.01). The positive rate of CD8 in the lamina propria tissues of UC at active stage was markedly higher than that at remissive stage (80% vs 34%, P = 0.0006). The expression of Fas was remarkably higher in the epithelia of UC tissues than that in the controls (62% vs 30%, P < 0.01), and its expression at active UC was also dramatically higher than that at remissive stage (84% vs 45%, P < 0.01). The expression of FasL was significantly increased in the inflammatory cells from the lamina propria of UC tissues as compared with that from normal mucosa (62% vs 7%, P < 0.01), and it was also a significant different between the active and remissive stage (88% vs 43%, P < 0.01). Furthermore, there was a correlation between the expression CD8 and FasL in the inflammatory cells from the lamina propria (χ² = 7.3, P < 0.01). The expression of Bcl-2/Bax was not different between UC and normal mucosa (P > 0.05).

CONCLUSION: The expression of Fas/FasL is up-regulated in UC, but the expression of Bcl-2/Bax is not obviously changed. CD8 T cells play important roles in the development of UC and they are closely related with Fas/FasL system.

Dual infection with Helicobacter bilis and Helicobacter hepaticus in p-glycoprotein-deficient mdr1a-/- mice results in colitis that progresses to dysplasia

Patients with inflammatory bowel disease (IBD) are at increased risk for developing high-grade dysplasia and colorectal cancer. Animal IBD models that develop dysplasia and neoplasia may help elucidate the link between inflammation and colorectal cancer. Mdr1a-/- mice lack the membrane efflux pump p-glycoprotein and spontaneously develop IBD that can be modulated by infection with Helicobacter sp: H. bilis accelerates development of colitis while H. hepaticus delays disease. In this study, we determined if H. hepaticus infection could prevent H. bilis-induced colitis. Unexpectedly, a proportion of dual-infected mdr1a-/- mice showed IBD with foci of low- to high-grade dysplasia. A group of dual-infected mdr1a-/- animals were maintained long term (39 weeks) by intermittent feeding of medicated wafers to model chronic and relapsing disease. These mice showed a higher frequency of high-grade crypt dysplasia, including invasive adenocarcinoma, possibly because H. hepaticus, in delaying the development of colitis, allows time for transformation of epithelial cells. Colonic epithelial preparations from co-infected mice showed increased expression of c-myc (5- to 12-fold) and interleukin-1alpha/beta (600-fold) by real-time polymerase chain reaction relative to uninfected wild-type and mdr1a-/- animals. This animal model may have particular relevance to human IBD and colorectal cancer because certain human MDR1 polymorphisms have been linked to ulcerative colitis and increased risk for colorectal cancer.

Quantitative measurement of cytokine mRNA in inflammatory bowel disease: relation to clinical and endoscopic activity and outcome

OBJECTIVE

The objective of this study was to quantitatively determine cytokine mRNA expression in inflammatory bowel disease under different clinical conditions including active disease, remission or an impaired response to a glucocorticoid (GC) therapy.

METHODS

Mucosal biopsies were taken from 33 patients with ulcerative colitis (UC), 21 patients with Crohn's disease (CD) and 11 controls. Peripheral blood mononuclear cells (PBMNC) were isolated from 24 CU patients, 18 CD patients and 11 controls. Cytokine-mRNA [interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-10, interferon gamma (IFN-gamma), tumour necrosis factor alpha (TNF-alpha)] expression was measured by quantitative reverse transcriptase-polymerase chain reaction in biopsies and PBMNC, and correlated to endoscopic findings, clinical activity and outcome after 6 months GC therapy.

RESULTS

IL-1beta, IL-6 and TNF-alpha were the largely dominating cytokines. In contrast to IL-1beta and TNF-alpha-, IL-6 expression was restricted to inflamed mucosa and correlated with the clinical activity and C-reactive protein levels in cases of pancolitis ulcerosa. TNF-alpha was elevated in CD even in endoscopic normal tissue. IL-2 and IFN-gamma were downregulated in PBMNC from CD and UC. No Th1 or Th2 specificity could be detected. Cytokine mRNA levels did not correlate with the response to a GC therapy.

CONCLUSION

IL-6 sharply distinguishes between inflamed and non-inflamed mucosa, and is therefore a suitable marker of intestinal inflammation. Its selective expression in the inflammatory site makes it an interesting target for future therapeutic strategies. TNF-alpha overexpression even in remission suggests a key role of this cytokine in CD pathogenesis and is possibly a feature that allows one to differentiate CD from UC.

Neutralization of interleukin-17 aggravates dextran sulfate sodium-induced colitis in mice

We evaluated the effects of rat anti-mouse IL-17 neutralizing monoclonal antibody (mAb) on the development of dextran sulfate sodium (DSS)-induced colitis. Tissue samples were evaluated by standard immunohistochemical procedure. The mucosal mRNA expression of cytokines was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). In the mice treated with the anti-IL-17 mAb, the body weight was significantly lower, and anal prolapse and colon shortening were apparent. A histological analysis indicated that the anti-IL-17 mAb markedly enhanced the severity of colitis. The mucosal infiltration of CD4-positive helper T cells and CD11b-positive granulocytes-monocytes was increased in the anti-IL-17 mAb-treated mice. Treatment with the anti-IL-17 mAb increased the mucosal expression of mRNAs of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, IL-6, RANTES, and IP-10. Blocking of IL-17 activity in vivo using the anti-IL-17 mAb enhanced the development of DSS-colitis in mice. This suggests an inhibitory role for IL-17 in the development of DSS-colitis.

Prolonged interferon-gamma exposure decreases ion transport, NKCC1, and Na+-K+-ATPase expression in human intestinal xenografts in vivo

IFN-gamma is elevated in intestinal inflammation and alters barrier and transport functions in human colonic epithelial cell lines, but its effects on normal human small intestinal epithelium in vivo are poorly defined. We investigated effects of prolonged IFN-gamma exposure on ion transport and expression of transporters by using human fetal small intestinal xenografts. Xenograft-bearing mice were injected with IFN-gamma, and 24 h later xenografts were harvested and mounted in Ussing chambers. Baseline potential difference (PD) was not affected by IFN-gamma treatment. However, conductance was enhanced and agonist-stimulated ion transport was decreased. IFN-gamma also decreased expression of the Na+-K+-2Cl- cotransporter and the alpha-subunit of Na+-K+-ATPase compared with controls, whereas levels of the calcium-activated Cl- channel and CFTR were unaltered. Thus prolonged exposure to IFN-gamma leads to decreased ion secretion due, in part, to decreased ion transporter levels. These findings demonstrate the implications of elevated IFN-gamma levels in human small intestine and validate the human intestinal xenograft as a model to study chronic effects of physiologically relevant stimuli.