Expression of leukocyte adhesion molecules by mucosal mononuclear phagocytes in inflammatory bowel disease

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.

Identification and validation of the common pathogenesis and hub biomarkers in Hirschsprung disease complicated with Crohn’s disease

Background

Although increasing evidence has supported that Hirschsprung disease (HSCR) is the risk factor for children developing Crohn’s disease (CD), the common mechanism of its co-occurrence remains unknown. The purpose of this study is to further explore the underlying mechanism and biomarkers for the co-occurrence of HSCR and CD.

Methods

The Gene Expression Omnibus (GEO) database was used to obtain gene expression profiles for CD (GSE95095) and HSCR (GSE98502). Following the identification of the shared differentially expressed genes (DEGs) of CD and HSCR, functional annotation, protein–protein interaction (PPI) network creation, and module assembly were performed to discover hub genes. RT-qPCR was performed to validate the expression of the hub genes in HSCR samples. The receiver operating characteristic (ROC) curve was utilized to assess the accuracy of the hub genes as biomarkers in predicting CD in both the training dataset and test dataset.

Results

A total of 103 common DEGs (50 downregulated genes and 53 upregulated genes) were chosen for further investigation. The importance of chemokines and cytokines in these two disorders is highlighted by functional analysis. MCODE plug identified three important modules, which functionally enriched the immune system process. Finally, nine hub genes were identified using cytoHubba, including IL1B, IL10, CXCL10, ICAM1, EGR1, FCGR3A, S100A12, S100A9, and FPR1. The nine hub genes were mainly enriched in immune- and inflammation-related pathways. External data profiles and RT-qPCR confirmed the expression of the nine hub genes in HSCR and CD. ROC analysis revealed that the nine hub genes had a strong diagnostic value.

Conclusion

Our study reveals the common pathogenesis of HSCR and CD. These hub genes and diagnostic models may provide novel insight for the diagnosis and treatment of HSCR complicated with CD.

GBP4 is an immune-related biomarker for patients with ileocolonic Crohn’s disease by comprehensive analysis

Background: Extensive evidence has shown that immune cell infiltration is associated with the pathogenesis of Crohn’s disease (CD).

Methods: Differentially expressed genes (DEGs) from the GSE179285 dataset in the intestinal mucosa of CD patients and healthy individuals were then identified. The infiltration pattern of 22 immune cell types was assessed using the CIBERSORT algorithm. The DEGs and 22 immune cell types were combined to find the key gene network using weighted gene co-expression network analysis (WGCNA). A linear regression model for the relationship between the expression of the hub genes in CD patients and infiltration of immune cells was also developed. The utility and accuracy of the hub genes for CD diagnosis were assessed using receiver operating characteristic (ROC) analysis. The accuracy of the model was validated using the GSE20881 dataset.

Results: There were 1135 DEGs between the intestinal mucosal tissue of CD patients and healthy individuals. Of these DEGs, 711 genes were upregulated, whereas 424 of them were downregulated. There was also a significant difference in the infiltration of immune cells to the intestinal mucosal between the CD patients and healthy individuals. WGCNA revealed that the turquoise module genes were strongly correlated with the infiltration of M1 macrophages (cor =0.68, p = 10−16). Finally, the expression of GBP4, the identified hub gene, strongly correlated with the infiltration of M1 macrophages (adjusted r-squared =0.661, p < 2×10−16), and is a relatively good marker for CD diagnostic prediction (AUC =0.736). The relationship between GBP4 expression and infiltration of M1 macrophages (adjusted r-squared =0.435, p < 2×10−16) and diagnostic value of the gene (AUC =0.702) were verified using the GSE20881 validation dataset.

Conclusion: The expression of GBP4 is associated with the infiltration of M1 macrophages to the intestinal mucosa of CD patients.

Microbial Signatures and Innate Immune Gene Expression in Lamina Propria Phagocytes of Inflammatory Bowel Disease Patients

BACKGROUND & AIMS

The interaction between intestinal microbiota and the immune system plays a vital role in inflammatory bowel disease (IBD). Although numerous deep-sequencing studies have suggested dysbiosis in IBD, identifying specific bacteria from the stool or mucosa that are responsible for disease susceptibility or severity has remained a challenge. Lamina propria phagocytes ideally are localized to interact with bacteria that are in close proximity to, or have invaded, the tissue. Thus, we examined the microbial populations associated with the lamina propria phagocytes in 20 Crohn's disease and 12 ulcerative colitis patients. Specifically, we aimed to address whether the phagocyte-associated microbiota differed from the mucosa-associated microbiota and whether this varied based on IBD type or the state of inflammation.

METHODS

16S ribosomal RNA gene sequencing and innate immune gene expression profiling was done on CD11b+ lamina propria phagocytes isolated from the biopsies obtained from IBD patients.

RESULTS

Phagocyte-associated microbiota was enriched in bacterial species belonging to phylum Proteobacteria, whereas species belonging to phylum Bacteroidetes were enriched in the mucosal microbiota of IBD patients. Disease type was the most influential factor in driving differences in the microbiota of both the mucosa and the lamina propria phagocytes, irrespective of inflammation state o`r anatomic location. Crohn's disease and ulcerative colitis specimens showed similar patterns of increased inflammatory gene expression in phagocytes isolated from inflamed areas compared with those isolated from uninflamed regions.

CONCLUSIONS

This pilot study shows the feasibility of using lamina propria phagocytes to characterize the microbiota in IBD patients. The approach used in this study can narrow the spectrum of potentially dysbiotic bacterial populations and clinically relevant gene expression signatures in IBD patients.

Bedside to bench: defining the immunopathogenesis of psoriatic arthritis

Psoriatic arthritis (PsA) is an immune-mediated, systemic inflammatory disorder. PsA can present with heterogeneous clinical features. Advances in understanding the immunopathogenesis of PsA have helped to facilitate the development of agents targeting specific components of the dysregulated inflammatory and immune responses relevant to PsA. Interestingly, agents with distinct mechanisms of action have shown differential responses across the various disease domains of PsA, counter to what might have been expected from basic science investigations. Here, we review data utilizing various novel targeted therapies for PsA, focusing on biologic and targeted synthetic therapies. These data might support the idea of a 'bedside to bench' concept, whereby results from clinical trials of specific targeted therapies inform our understanding of the immunopathogenesis of PsA. For example, TNF inhibition confers substantial and comparable benefit for all domains of PsA, supporting the view that TNF is a central pro-inflammatory cytokine across diverse areas of disease involvement. On the other hand, inhibition of IL-12-IL-23, as compared with inhibition of TNF, has greater efficacy for psoriasis, comparable efficacy for peripheral arthritis, but was ineffective in studies of axial spondyloarthritis. Data from studies of agents with distinct mechanisms of action will help to further refine our understanding of the immunopathogenesis of PsA.

Interfering with leukocyte trafficking in Crohn's disease

The discovery of gut-specific leukocytes and the ability to modulate their function has been a groundbreaking development in the treatment of inflammatory bowel disease. Drugs target the interaction between lymphocytes and endothelial cells via integrins and their ligand cellular adhesion molecules. Safety, efficacy and sustainability of effect are key to this drug class, notwithstanding the association of natalizumab with fatal polyoma virus infection. Vedolizumab (2014) now licensed for the treatment of Crohn's disease around the world provides gut-specific immunosuppression. Targets for modulators of leukocyte trafficking include (examples in brackets) ICAM-1 (alicaforsen, efalizumab); MAdCAM-1 (PF-00547 659); α4 and related receptors (abrilumab, etrolizumab, natalizumab, vedolizumab); chemokine receptor CCR9 (vercirnon); and sphingosine 1-phosphate receptors (etrasimod, fingolimod, ozanimod). Oral and subcutaneous therapies are in development. The safety, efficacy and practice points of licensed drugs are discussed, in addition to initial results from therapeutic trials.

Anti-inflammatory effect of Euphorbia supina extract in dextran sulfate sodium-induced colitis mice

The aim of this study is to examine the anti-inflammatory effect of Euphorbia supina (ES) ethanol extract in dextran sulfate sodium (DSS)-induced experimental colitis model. ES was per orally administered at different doses of 4 or 20 mg/kg body weight with 5% DSS in drinking water for 7 days. Twenty mg/kg of ES administration regulated body weight decrease, recovered colon length shortening, and increased disease activity index score and myeloperoxidase level in DSS-induced colitis. Histological features showed that 20 mg/kg of ES administration suppressed edema, mucosal damage, and the loss of crypts induced by DSS. Furthermore, ES suppressed the expressions of COX-2, iNOS, NF-kB, IkBα, pIkBα in colon tissue. These findings demonstrated a possible effect of amelioration of ulcerative colitis and could be clinically applied.

Increased Cell Adhesion Molecules, PECAM-1, ICAM-3, or VCAM-1, Predict Increased Risk for Flare in Patients With Quiescent Inflammatory Bowel Disease

GOALS AND BACKGROUND

Predicting the risk of flare-ups for patients with inflammatory bowel disease (IBD) is difficult. Alterations in gut endothelial regulation of mucosal immune homeostasis might be early events leading to flares in IBD. Cell adhesion molecules (CAMs), in particular, are important in maintaining endothelial integrity and regulating the migration of leukocytes into the gut.

STUDY

We evaluated the mRNA expression of various tight junction proteins, with an emphasis on CAMs, in 40 patients with IBD in clinical remission. Patients were retrospectively assessed at 6, 12, and 24 months after baseline colonoscopy, and at the end of all available follow-up (maximum 65 mo), for flare events to determine whether baseline mRNA expression was associated with subsequent flares.

RESULTS

At all follow-up points, the baseline expression of platelet endothelial cell adhesion molecule-1 (PECAM-1), ICAM-3, and VCAM-1 was significantly higher in patients who flared than in those who did not (2.4-fold elevation, P=0.012 for PECAM-1; 1.9-fold increased, P=0.03 for ICAM-3; and 1.4-fold increased, P=0.02 for VCAM-1). PECAM-1 and ICAM-3 expression was significantly increased in patients who flared as early as 6 months after baseline colonoscopy. In contrast, there were no significant differences between patients with and without flares in baseline expression of other CAMs (ESAM, ICAM-1, ICAM-2, E-selectin, P-selectin, and MadCAM1).

CONCLUSIONS

Increased expression of PECAM-1, ICAM-3, and VCAM-1 in colonic biopsies from patients with IBD in clinical remission is associated with subsequent flares. This suggests that increases in the expression of these proteins may be early events that lead to flares in patients with IBD.

Genetic risk variants as therapeutic targets for Crohn's disease

INTRODUCTION

The pathogenesis of Inflammatory bowel diseases (IBD) is multifactorial, with interactions between genetic and environmental factors. Despite the existence of genetic factors being largely demonstrated by epidemiological data and several genetic studies, only a few findings have been useful in term of disease prediction, disease progression and targeting therapy. Areas covered: This review summarizes the results of genome-wide association studies in Crohn's disease, the role of epigenetics and the recent discovery by genetic studies of new pathogenetic pathways. Furthermore, it focuses on the importance of applying genetic data to clinical practice, and more specifically how to better target therapy and predict potential drug-related toxicity. Expert opinion: Some genetic markers identified in Crohn`s disease have allowed investigators to hypothesize about, and in some cases, prove the usefulness of new specific therapeutic agents. However, the heterogeneity and complexity of this disease has so far limited the daily clinical use of genetic information. Finally, the study of the implications of genetics on therapy, either to predict efficacy or avoid toxicity, is considered still to be in its infancy.

Targeting leukocyte trafficking for the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic immune-mediated inflammatory disease of the intestine that includes both Crohn's disease and ulcerative colitis, and afflicts nearly 1 million people throughout North America. As our understanding of IBD pathogenesis grows, several new therapies have been developed that use monoclonal antibodies to specifically target key mediators and biological pathways implicated in IBD immune dysfunction. One important pathway involves leukocyte trafficking and infiltration into the affected intestinal tissues. This review provides a summary of the different therapies that have been developed to inhibit leukocyte trafficking to the inflamed gut, and evaluates the relative safety and efficacy of these novel drugs within the context of existing medical therapies for IBD.

Caco-2 cell line as a model to evaluate mucoprotective proprieties

Physical protection of mucosa surface and reduction of inflammatory processes are currently considered the main strategies in the treatment and prevention of mucosal diseases. However, the majority of models used to verify the activity of new mucoprotective agents are based on limiting instrumental assessment or the sacrifice of experimental animals. In this study, for the first time, some in vitro experimental methods using Caco-2 cell line are proposed as predicting in vivo behaviour and action of mucoprotective agents. To this purpose, hyaluronic acid and natural polysaccharides for their bioadhesive activity, hydrocortisone and natural polyphenols as anti-inflammatory agents have been chosen. The obtained results demonstrated that the techniques (Con A/o-pd assay and Franz cell system) of mucoadhesive evaluation on Caco-2 cells are useful to compare the activity of each experimental sample and to assess the adhesion time to the mucosal cell surface. Moreover, the reduction of intercellular adhesion molecule-1 (ICAM-1) expression in Caco-2 cells can be considered directly correlated to the mucosal anti-inflammatory effect induced by the hydrocortisone and natural polyphenols. In conclusion, the study supported the use of Caco-2 cell as a model to compare and investigate the effect of different active substances on the mucosa and its diseases.

CD11c+ cells are significantly decreased in the duodenum, ileum and colon of dogs with inflammatory bowel disease

CD11c serves as a marker for human and murine dendritic cells (DCs) and cells expressing this marker have been shown to have similar morphological and functional characteristics in the canine immune system. The aim of this study was to quantify CD11c(+) cells in the duodenum, ileum and colon of healthy dogs and dogs with inflammatory bowel disease (IBD). Endoscopic biopsies from the duodenum (n=12 cases), ileum (n=8 cases) and colon (n=12 cases) were obtained from dogs diagnosed with IBD. Intestinal tissue from 10 healthy beagle dogs was used as control. Immunofluorescence microscopy was carried out using an anti-canine CD11c monoclonal antibody. Labelled cells were recorded as cells per 120,000 μm(2). The canine chronic enteropathy clinical activity index (CCECAI) was calculated for all dogs with IBD. In addition, sections from all dogs with IBD were evaluated according to the guidelines of the World Small Animal Veterinary Association Gastrointestinal Standardization Group. The number of CD11c(+) cells in the duodenum, ileum and colon of dogs with IBD was significantly reduced compared with controls (P<0.01, P<0.01 and P<0.05, respectively). There was a significant negative correlation between the number of CD11c(+) cells in the colon of dogs with IBD and the CCECAI (P=0.044, r(2)=-0.558). Chronic inflammation in canine IBD appears to involve an imbalance in the intestinal DC population. Future studies will determine whether reduced expression of CD11c could be a useful marker for the diagnosis and monitoring of canine IBD.

LFA-1 and ICAM-1 Molecule Expression in Jejunal Mucosa from Children with Autoimmune Enteropathy

The expression of adhesion molecules by cells of the small intestinal mucosa was compared in gut biopsies from children with autoimmune small intestinal enteropathy and normal controls and related to HLA-DR expression by the same tissue. Jejunal biopsies were stained by IFL with monoclonal antibodies to LFA-1 (TS1/22 and CD11a/25.3.1) and ICAM-1 (RR1/1 and 84H10) molecules. LFA-1 and ICAM-1 positive cells were observed in the lamina propria in all cases and the counts were increased in autoimmune enteropathy compared with controls. In addition, in 4 of 7 cases of autoimmune enteropathy crypt enterocytes were positives for ICAM-1 when stained with RR1/1 and 3 of the 4 were also positive for LFA-1 when stained with both LFA-1 reagents. We speculate on the role of adhesion molecule expression in autoimmune enteropathy.

Pathogenesis of and unifying hypothesis for idiopathic pouchitis

Ileal pouch-anal anastomosis is the procedure of choice in the surgical management of refractory ulcerative colitis. Pouchitis affects up to 60% of patients following ileal pouch-anal anastomosis for ulcerative colitis. It overlaps significantly with ulcerative colitis such that improvements in our understanding of one will impact considerably on the other. The symptoms are distressing and impinge significantly on patients' quality of life. Despite 30 years of scientific and clinical investigation, the pathogenesis of pouchitis is unknown; however, recent advances in molecular and cell biology make a synergistic hypothesis possible. This hypothesis links interaction between epithelial metaplasia, changes in luminal bacteria (in particular sulfate-reducing bacteria), and altered mucosal immunity. Specifically, colonic metaplasia supports colonization by sulfate-reducing bacteria that produce hydrogen sulfide. This causes mucosal depletion and subsequent inflammation. Although in most cases antibiotics lead to bacterial clearance and symptom resolution, immunogenetic subpopulations can develop a chronic refractory variant of pouchitis. The aims of this paper are to discuss proposed pathogenic mechanisms and to describe a novel mechanism that combines many hypotheses and explains several aspects of pouchitis. The implications for the management of both pouchitis and ulcerative colitis are discussed.

Expression of apoptotic epithelial cells within lamina propria beneath the basement membrane triggers dextran sulfate sodium-induced colitis

We postulated that nuclear dust within the lamina propria beneath the basement membrane of the epithelium in colonic mucosa is a form of apoptotic epithelial cells and that its expression triggers dextran sulfate sodium-induced colitis. The aim was to determine the origin of nuclear dust and to explore the correlation between nuclear dust expression and clinicopathologic parameters of colitis. Rats were treated with 3% dextran sulfate sodium. Cells showing double positive staining with cytokeratin and TdT-mediated uUTP-biotin nick-end labeling technique were apoptotic cells derived from epithelial cells. Nuclear dust expression on day 5 correlated with bloody stools and a decrease of mitotic colonic cells just before ulceration. Examination of cultures under light and fluorescent microscopy showed that dextran sulfate sodium caused early apoptosis and late apoptosis or necrosis. Our results suggest that interventions directed toward the apoptotic process may be beneficial in the treatment of ulcerative colitis.

Adhesion molecules in chronic ulcerative colitis

BACKGROUND AND AIMS

The adhesion molecule expression in colonic mucosa is pivotal for transition from quiescent to active stage of ulcerative colitis (UC). The aim of the present study is to reveal the adhesion molecule profile of colonic mucosa in the active stage of UC and in remission.

MATERIALS AND METHODS

Biopsy specimens obtained from 14 patients with UC (seven with active disease and seven with UC in remission) and from seven controls were used. Immunohistochemistry was performed with antibodies against ICAM-1, VCAM-1, E-selectin, LFA-1, Mac-1, and VLA-4.

RESULTS

In controls, slight ICAM-1 positivity was observed on thety endothelium of blood vessels of the mucosal and submucosal layer and only single ICAM-1-, Mac-1-, and LFA-1-positive cells were found. In all patients with UC, the endothelium of venules in the edematous mucosal and submucosal layers was ICAM-1-, VCAM-1-, and E-selectin-positive. Numerous ICAM-1- and LFA-1-positive and less VCAM-1-, Mac-1-, and VLA-4-positive inflammatory cells were detected in mucous layers of acute UC. In specimens of UC in remission, the inflammatory cells positive for the studied adhesion molecules were significantly less in number in the mucosa and submucosa (p < 0.05).

CONCLUSIONS

Based on the increased expression of ICAM-1, VCAM-1, and their ligands LFA-1 and VLA-4 in patients with UC, we can conclude that these adhesion molecules play a key role in the adherence of lymphocytes and macrophages to endothelial cells maintaining the chronic inflammation. Presence of E-selectin on endothelial cells of venules could be a sign of relapse after remission in UC.

Endothelin-1 receptor antagonist (LU-135252) improves the microcirculation and course of TNBS colitis in rats

The role of microcirculation in the pathogenesis and course of chronic inflammatory bowel disease is still unclear. The aim of this study was the evaluation of the role of microcirculation in colitis activity in the rat TNBS (trinitrobenzenesulfonic acid) colitis model using endothelin-1 and a selective endothelin-1 receptor antagonist (LU-135252). Target parameters were capillary blood flow, functional capillary density, vascular permeability, and leukocyte sticking as well as recording of hematocrit, weight course, diuresis, stool quality, and degree of inflammation using a histological colitis score. The acute phase of TNBS colitis is characterized by an extensive disturbance of microcirculation (a significant decrease in capillary blood flow and capillary density and a significant increase in capillary permeability and leukocyte sticking in the mucosa). There is also a significant increase in hematocrit and a significant decrease in diuresis and weight. An exogenous supply of endothelin-1 does not lead to an aggravation of these disorders because of a possible blockage of the endothelin-1 receptors by endogenous endothelin-1 in this florid inflammatory phase. Applying the selective endothelin-1 receptor A antagonist LU-135252 leads to a significant improvement of all microcirculatory parameters and clinical findings compared to the untreated colitis group. Direct improvement of capillary blood flow in the early phase of colitis leads to reduced colitis activity, which underscores the pathogenetic role of the microcirculation in the progression of colitis.

Selective COX-2 inhibition reduces leukocyte sticking and improves the microcirculation in TNBS colitis

The role of cyclooxygenase-2 inhibitors in the course of experimental colitis is controversially discussed. The aim of this study was to evaluate leukocyte-endothelium interaction and colitis activity after applying the selective cyclooxygenase-2 inhibitor NS-398 in a rat trinitrobenzene sulfonic acid (TNBS) colitis model. The acute phase of TNBS colitis is characterized by a significant reduction of capillary blood flow, capillary density, diuresis, and weight and a significant increase in capillary permeability, leukocyte sticking, and hematocrit. Applying the selective cyclooxygenase-2 inhibitor NS-398 leads to a significant improvement of all microcirculatory parameters and clinical findings compared to the (untreated) colitis group. There are no histopathological differences between the individual colitis groups. Acute colitis is characterized by an extensive disturbance of microcirculation together with signs of systemic inflammatory response syndrome. These alterations are significantly improved by inhibiting cyclooxygenase-2. The results support the described correlation between cyclooxygenase activation and leukocyte-endothelium interaction. Moreover, they underscore the postulated relation between leukocyte-endothelium interaction and capillary blood flow.

Current concept on the pathogenesis of inflammatory bowel disease-crosstalk between genetic and microbial factors: Pathogenic bacteria and altered bacterial sensing or changes in mucosal integrity take “toll”

The pathogenesis of inflammatory bowel disease (IBD) is only partially understood. Various environmental and host (e.g. genetic-, epithelial-, immune and non-immune) factors are involved. It is a multifactorial polygenic disease with probable genetic heterogeneity. Some genes are associated with IBD itself, while others increase the risk of ulcerative colitis (UC) or Crohn’s disease (CD) or are associated with disease location and/or behaviour. This review addresses recent advances in the genetics of IBD. The article discusses the current information on the crosstalk between microbial and genetic factors (e.g. NOD2/CARD15, SLC22A46A5 and DLG5). The genetic data acquired in recent years help in understanding the pathogenesis of IBD and can identify a number of potential targets for therapeutic intervention. In the future, genetics may help more accurately diagnose and predict disease course in IBD.

Crohn's disease recurrence in a small bowel transplant

This is a report of a patient with short-bowel syndrome secondary to recurrent surgeries for Crohn's disease who ultimately required small bowel transplantation in 1994. Eight years posttransplantation he developed recurrent Crohn's disease that was responsive to prednisone. From the perspective of advancing our understanding of Crohn's disease pathogenesis this case suggests that intestine-specific antigens may be more important than the classical MHC antigens for the development of Crohn's disease, since this man developed Crohn's disease in both the native intestine and also in the engrafted one.

Expression of ICAM-1 in colon epithelial cells: an ultrastructural study performed on in vivo and in vitro models

BACKGROUND

Studies have suggested that in ulcerative colitis (UC), intercellular adhesion molecule-1 (ICAM-1) is involved in migration of leukocytes toward the colonic epithelium. A suitable in vitro model of chronic colonic inflammation does not exist, and the role of the epithelium is based on monolayers of cancer cells. Conflicting results exist on epithelial ICAM-1 expression, and the aim of this study was to compare the expression in various models of colonic epithelium.

MATERIALS AND METHODS

Colonic biopsies from four UC patients and four controls were examined by cryoimmuno-electron microscopy using ICAM-1-antibodies. In four other controls, the epithelium was isolated from colonic biopsies, embedded in collagen, and evaluated similarly. Isolated crypts and cultured cancer cells were stimulated with interferon-gamma (IFN-gamma) or tumor necrosis factor-alpha (TNF-alpha).

RESULTS

ICAM-1 was not expressed in the biopsies. In contrast, HT29 cells and the collagen-embedded crypts expressed ICAM-1 on the apical membranes proximal to the junctional complexes when stimulated with IFN-gamma or TNF-alpha in a dose-related manner.

CONCLUSIONS

ICAM-1 is not expressed on colonic epithelium in vivo. However, both colonocytes and HT29 cells were capable of expressing ICAM-1 on their apical membranes in response to supraphysiologic cytokine concentrations. These observations question the justification of extrapolating observations from colon cancer cell lines to in vivo inflammatory conditions.

Connections between psoriasis and Crohn's disease

The prevalence of psoriasis in patients with Crohn's disease (CD) is higher than chance would allow if they were mutually exclusive diseases. A close examination reveals genetic and pathologic connections between these diseases. An appreciation for the role of tumor necrosis factor-alpha in both diseases has proven very important. Increased levels of this inflammatory cytokine have been measured in CD lesions, and in 1997 a clinical trial demonstrated the response of this disease to infliximab, a monoclonal antibody specific for tumor necrosis factor-alpha. A subsequent clinical trial evaluated infliximab in a patient with CD and psoriasis, another disease in which increased levels of tumor necrosis factor-alpha are seen in lesions. Scientists noticed the marked skin improvement of this patient and later demonstrated the efficacy of infliximab for psoriasis in a randomized, double-blind, placebo-controlled trial. Thus, an appreciation for connections between psoriasis and CD can suggest novel therapeutic strategies with ensuing benefits to patients. This article reviews epidemiologic, genetic, and pathologic connections between psoriasis and CD and discusses pharmaceuticals targeting inflammatory mediators common to each disease. (J Am Acad Dermatol 2003;48:805-21.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should understand how psoriasis and Crohn's disease are related at epidemiologic, genetic, and pathological levels and should appreciate how to use this knowledge to treat these diseases.

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IL-10 producing CD14low monocytes inhibit lymphocyte-dependent activation of intestinal epithelial cells by commensal bacteria

Intestinal epithelial cell (IEC) activation by non-pathogenic, commensal bacteria was demonstrated to require the presence of immunocompetent cells. In this study, HT-29 and CaCO-2 transwell cultures, reconstituted with CD4+ and CD8+ T cells, CD19+ B cells and CD14high monocytes, were challenged with non-pathogenic Gram negative Escherichia coli and Gram positive lactobacilli. Cytokine expression was analysed by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assays (ELISA). Expression of tumour necrosis factor alpha (TNF-alpha) and interleukin (IL)-8 mRNA in E. coli or L. sakei challenged IEC was promoted by lymphocyte populations predominantly CD4+ T cells, while monocytes failed to mediate an inflammatory cytokine response. The monocyte phenotype and function were further characterised by flow cytometry and mixed lymphocyte reaction (MLR). During the co-culture with IEC and bacterial stimulated IEC, CD14high peripheral blood monocytes acquired a CD14low CD16low phenotype with reduced expression co-stimulatory (CD80, CD86, CD58) cell surface molecules. Immunosuppressive functions of IEC conditioned CD14low monocytes were demonstrated by the predominant secretion of IL-10 and IL-IRa and their reduced potential to trigger an allogeneic lymphocyte response. In conclusion, IEC contribute to the development of CD14low CD16low monocytes with immunosuppressive function and antagonised a lymphocyte-mediated activation of the intestinal epithelium in response to intestinal and food derived bacteria. These results strengthen the hypothesis that the gut epithelium constitutes an important functional element in the regulation of mucosal immune homeostasis towards commensal bacteria.

Increase in lymphoid follicles and leukocyte adhesion molecules emphasizes a role for the gut in spondyloarthropathy pathogenesis

The aim of this study was to investigate the expression of leukocyte adhesion molecules and the number of lymphoid follicles in gut mucosa of patients with spondyloarthropathy (SpA) in comparison with controls, in search for early immune alterations in the development of SpA-related gut inflammation. Histological evaluation and immunohistochemistry were performed on the ileum and colon of 14 SpA patients without macroscopic or microscopic gut inflammation and those of 21 controls. Lymphoid follicles were counted and immunohistochemical staining for leukocyte adhesion molecules, lymphocyte subtypes, macrophages, and plasma cells was scored semi-quantitatively. The number of lymphoid follicles was increased in both the ileum (p < 0.01) and the colon (p < 0.01) of SpA patients. SpA ileum showed an increase in leukocytes expressing CD11c (p < 0.01), whereas CD11a(+) (p < 0.02) and VCAM-1(+) cells (p < 0.05) were increased in SpA colon. Macrophages, characterized by the expression of CD68, were more numerous in colonic mucosa from SpA patients (p < 0.05). The amount of lymphoid follicles and lamina propria mononuclear cells expressing CD11a, CD11c, and VCAM-1 was increased in non-inflamed gut mucosa from SpA patients. These findings might point to increased antigen handling and presentation and augmented maturation of naïve T cells towards memory T cells in the SpA gut, which supports the concept that the gut is involved in the pathogenesis of SpA.

Amelioration of chronic and spontaneous intestinal inflammation with an antisense oligonucleotide (ISIS 9125) to intracellular adhesion molecule-1 in the HLA-B27/beta2 microglobulin transgenic rat model

Adhesion molecules are known to be an important part of leukocyte migration and extravasation in both homeostatic and inflammatory conditions. Intracellular adhesion molecule-1 (ICAM-1 or CD54) is constitutively expressed on endothelial cells and is up-regulated during acute and chronic inflammation. We investigated the efficacy and consequences of interfering with CD54 after administration of an antisense oligonucleotide to ICAM-1 (CD54) in the transgenic HLA-B27/beta2 microglobulin rat model. One hundred percent of the HLA-B27 transgene + animals will spontaneously develop chronic inflammation (some more severely than others) in the gastric mucosa, cecum, and colon. We carried out two studies, i.p. injection and rectal administration of antisense. Following i.p. and rectal treatment, there were significant decreases in colonic mucosal wall thickness, histologic inflammation, CD54 expression in the colon and peripheral blood, and the percentage of colon weight per end body weight. Furthermore, decreased expression of CD49d, CD18, and tumor necrosis factor-alpha was observed in antisense treated rats. Therefore, the HLA-B27 transgenic model of spontaneous and chronic inflammatory bowel disease, which has increased expression of adhesion molecules, responds to both routes of administration of ICAM-1 antisense oligonucleotides. These studies support the regulatory role of adhesion molecules in chronic intestinal inflammation, the need for an understanding of how the route of drug delivery can alter the dose and area affected, and finally the role of antisense oligonucleotides as a therapeutic modality in chronic spontaneous inflammatory bowel diseases.

Alteration in expression of beta 2 integrins on lamina propria lymphocytes in ulcerative colitis and Crohn's disease

We have previously demonstrated by immunohistochemistry that mucosal expression of beta 2 integrins was enhanced in Crohn's disease and ulcerative colitis as compared to normal controls. We aimed, therefore, to determine whether there was a corresponding alteration in the expression of CD11a/CD18 (LFA-1), the primary lymphocyte beta 2 integrin, among the principal subsets of lamina propria lymphocytes (LPLs). Accordingly, LPLs were extracted from surgical resection specimens derived from patients with Crohn's colitis, ulcerative colitis, and from noninflamed controls. Following immunofluorescent staining, three-color flow-cytometry analysis identified LPLs on the basis of CD45 side scatter gating, which in turn, were further subdivided into CD4(+), CD8(+), and CD19(+) cells to account for the predominant T and B cells in the lamina propria. Expression patterns of CD11a, the alpha-subunit of LFA-1; CD18, the beta-subunit of LFA-1; and alpha d, a novel alpha-subunit of the beta 2 integrin family were assessed for each of these lymphocyte subsets. In Crohn's disease and ulcerative colitis there was an increased mean percentage expression of CD4(+) cells and CD11a(+) cells compared with noninflamed controls. CD11a was more likely to be expressed on CD4(+) cells in both Crohn's disease and ulcerative colitis and compared with controls and less expressed on CD19(+) cells. It is likely that an influx of CD4(+)11a(+) cells into the lamina propria accounted for these changes. These results suggest that although currently there is great interest in harnessing alpha 4 beta 7 in treatment of inflammatory bowel disease, further consideration should be given to the role of CD11a in these disease states.

Differential expression of cell adhesion molecules within inflamed ileal pouch mucosa: relationship to recruited cell subtypes

INTRODUCTION

Endothelial-bound cell adhesion molecules are important in recruiting inflammatory cells to the mucosa in inflammatory bowel disease (IBD). Little is known of the expression of these molecules in relation to the recruitment of particular cell subtypes in the early course of mucosal inflammation. We therefore studied the expression of several adhesion molecules to examine their potential correlation with the cellular infiltrate in the inflamed ileal pouch, a possible disease model for ulcerative colitis.

METHODS

Eleven patients (group 1) with familial adenomatous polyposis (FAP) with no evidence of ileal pouch inflammation and 14 patients (group 2) with ileal pouch inflammation (all with a prior diagnosis of ulcerative colitis) underwent pouch endoscopy with biopsy. Cryostat sections of biopsies were immunostained using a three-stage immunoperoxidase method for the adhesion molecules intercellular adhesion molecule (ICAM-1), vascular cellular adhesion molecule (VCAM-1), E-selectin and mucosal addressin cell adhesion molecule 1 (MAdCAM-1). These results were correlated with immunostaining for the cell markers CD3, CD4, CD8, CD45RO, CD14 and CD15, which were quantified by computer image analysis.

RESULTS

MAdCAM-1, ICAM-1 and VCAM-1 were expressed to similar degrees on the endothelia of groups 1 and 2. In contrast, E-selectin was significantly increased in group 2 (P = 0.003) and correlated with immunostaining for CD15 (r = 0.72), CD4 (r = 0.55) and CD14 (r = 0.53). MAdCAM-1 expression did not correlate with any cell subset. CD15 was the only cell marker to be altered significantly, being increased in group 2 (P = 0.002).

CONCLUSIONS

The inflammatory process seen in ileal pouch inflammation is characterized by up-regulation of E-selectin and recruitment of CD15-positive cells, emphasizing the role of neutrophil recruitment and migration to the epithelium in the pathogenesis of this condition.

Polymorphisms of the ICAM-1 gene are associated with inflammatory bowel disease, regardless of the p-ANCA status

The intercellular adhesion molecule-1 (ICAM-1) is of paramount importance for the initiation and propagation of various inflammatory conditions. An increased frequency of allele R241 of the ICAM-1 gene was previously described in p-ANCA-negative as compared to p-ANCA-positive ulcerative colitis and vice versa in Crohn's disease. One hundred sixteen healthy unrelated controls, 121 patients with ulcerative colitis, and 96 patients with Crohn's disease were genotyped for two polymorphisms of the ICAM-1 gene (R/G241, exon 4; and K/E469, exon 6), employing dot-blot hybridization and stratified according to their p-ANCA status. When compared with the control group the frequency of the allele R241 (P = 0.024) and the heterozygous genotype R/G241, P = 0.032) were significantly increased in ulcerative colitis, whereas the homozygous genotype G/G241 was found less frequently (P = 0.022). The heterozygous genotype K/E469 was observed less frequently (P = 0.001 and 0.037, resp.) than the homozygous genotype E/E469, which was more frequent in Crohn's disease and ulcerative colitis (P = 0.002 and 0.012, respectively). Further significant differences concerning the allele or genotype distribution were not observed. After stratification for the p-ANCA status significant differences concerning the frequencies of both the R241 and the E469 alleles were not detected when p-ANCA-positive inflammatory bowel disease and p-ANCA-negative inflammatory bowel disease were compared. Ulcerative colitis and Crohn's disease are associated with polymorphisms of the ICAM-1 gene, which might therefore represent a functional candidate gene. However, the observed associations are independent of the p-ANCA status.

Subtractive screening reveals up-regulation of NADPH oxidase expression in Crohn's disease intestinal macrophages

Macrophages play a central role during the pathogenesis of inflammation. In normal intestinal mucosa surface expression of typical macrophage markers such as CD14, CD16, CD11b or T-cell co-stimulatory molecules such as CD80 or CD86 is low indicating anergy and low pro-inflammatory activity of these cells. During inflammatory bowel disease (IBD) the mucosa is invaded by a population of macrophages displaying these markers, secreting higher cytokine levels and representing an activated cell population. CD33(+) cells (macrophages) were isolated from normal and Crohn's disease mucosa and mRNA was isolated by polyT magnetic beads. A subtractive screening was performed subtracting mRNA from normal macrophages from those of Crohn's disease macrophages. Oxidative burst activity was determined by flow cytometry. Seventy clones were obtained by the subtractive mRNA screening. Sequencing showed > 99% homology to mRNA of monocyte chemoattractant protein-1 (MCP-1) for three clones. Five clones obtained by subtraction revealed > 99% homology to mRNA of cytochrome b (subunit gp91). Differential expression of the cytochrome b subunit gp91 and the cytosolic NADPH oxidase subunit p67 was confirmed by RT-PCR and 'virtual' Northern blots. The fluorescence ratio of stimulated versus unstimulated cells was 0.9 +/- 0.16 in control macrophages indicating a lack of oxidative burst activity. In Crohn's disease this ratio was significantly increased to 1.80 +/- 0.8 (P = 0.004) confirming the molecular data. In conclusion NADPH oxidase mRNA is down-regulated or absent in macrophages from normal mucosa correlating with a lack of oxidative burst activity. In IBD macrophage-oxidative burst activity is increased and NADPH oxidase mRNA induced. Inhibition of NADPH oxidase could be a new therapeutical target in IBD and reduce mucosal tissue damage in active IBD.

Colonic epithelial cells induce endothelial cell expression of ICAM-1 and VCAM-1 by a NF-kappaB-dependent mechanism

Epithelial cells are positioned in close proximity to endothelial cells. A non-contact coculture system was used to investigate whether colonic epithelial cells activated with various cytokines are able to provide signals that can modulate ICAM-1 and VCAM-1 expression on endothelial cells. Coculture of human umbilical vein endothelial cells (HUVEC) and human microvascular endothelial cells (HMEC-1) with TNF-alpha/IFN-gamma-stimulated human colon epithelial cell lines led to a significant up-regulation of endothelial ICAM-1 and VCAM-1 expression. Increased ICAM-1 and VCAM-1 expression by endothelial cells was accompanied by an increase in endothelial cell NF-kappaB p65 and NF-kappaB-DNA-binding activity. Inhibition of endothelial NF-kappaB activation using the proteosome inhibitors MG-132 and BAY 11-7082 resulted in a significant decrease of ICAM-1 expression, indicating an important role for NF-kappaB in this response. This cross-talk may represent a biological mechanism for the gut epithelium to control the colonic inflammatory response and the subsequent immune cell recruitment during inflammation.

Soluble adhesion molecules in inflammatory bowel disease

BACKGROUND

Soluble adhesion molecules are elevated in a number of inflammatory conditions.

AIMS

To investigate the correlation of soluble intercellular adhesion molecule-1 (sICAM-1) and sE-selectin with the activity of inflammatory bowel disease (IBD).

METHODS

sICAM-1 and sE-selectin were measured by an enzyme-linked immunosorbent assay (ELISA) in 53 patients with ulcerative colitis (UC) and 38 patients with Crohn's disease (CD).

RESULTS

Patients with active UC and CD had significantly higher sICAM-1 than patients with inactive disease and controls. Patients with pancolitis had significantly higher levels than patients with distal colitis. There was a significant difference in sE-selectin levels between patients with active CD and control sICAM-1. sE-selectin did not correlate with the Harvey Bradshaw index (HBI). C-reactive protein (CRP) and microalbuminuria were better markers than sICAM-1 or sE-selectin which correlated with serum tumour necrosis factor (TNF)-alpha.

CONCLUSION

sICAM-1 and sE-selectin are elevated in the serum of patients with IBD but CRP and microalbuminuria reflect clinical disease activity more accurately. This study does not support the routine use of soluble adhesion molecules as disease activity markers in IBD.

Role of intercellular adhesion molecule 1 in indomethacin-induced ileitis

Adhesion molecules have been implicated in the pathogenesis of inflammatory bowel diseases. We investigated their expression and contribution to leukocyte recruitment in experimental intestinal inflammation. Ileitis was induced in Sprague-Dawley rats by two injections of indomethacin (7.5 mg/kg), given 24 h apart. Endothelial intercellular adhesion molecule-1 (ICAM-1) expression was quantified using the dual radiolabeled monoclonal antibody technique and Mac-1 (CD11b/CD18) expression on leukocytes by flow cytometry. Leukocyte infiltration was monitored by tissue myeloperoxidase (MPO) activity. The first indomethacin injection induced a time- and site-dependent increase of ICAM-1 expression in ileal mucosa and muscularis. The second injection resulted in a reduction of ICAM-1 expression below constitutive levels whereas Mac-1 was upregulated. MPO changes paralleled lesion development over 48 h. ICAM-1 and MPO values were correlated for the first 24 h. Immunoneutralization of either ICAM-1 or Mac-1 attenuated mucosal injury. We conclude that (i) indomethacin-induced ileitis is associated with a temporally disassociated upregulation of ICAM-1 and (ii) despite a reduction in ICAM-1 after 24 h, ICAM-1, in concert with Mac-1, contributes to mucosal injury and leukocyte infiltration elicited by indomethacin.

Recent advances in inflammatory bowel disease

The last decade has seen tremendous advances in our knowledge, which has led to genuine improvements in our understanding of the pathogenesis and management of inflammatory bowel disease (IBD). The combined power of cellular and molecular biology has begun to unveil the enigmas of IBD, and, consequently, substantial gains have been made in the treatment of IBD. Refinements in drug formulation have provided the ability to target distinct sites of delivery, while enhancing the safety and efficacy of older agents. Simultaneous progress in biotechnology has fostered the development of new agents that strategically target pivotal processes in disease pathogenesis. This article addresses our current understanding of the pathogenesis of IBD, including the latest developments in animal models and covers agents currently used in the treatment of IBD as well as emerging therapies.

Detection of ICAM-1 in experimentally induced colitis of ICAM-1-deficient and wild-type mice: an immunohistochemical study

Adhesion molecules (e.g. ICAM-1, CD 54) are known to be upregulated on activated vascular endothelial cells during inflammatory reactions. To study the role of ICAM-1 in intestinal inflammation in vivo, we induced acute experimental colitis in wild-type (C57BL/6) mice and ICAM-1-deficient mice, by feeding the animals with 3% dextran sodium sulphate (DSS) in drinking water for 7 days. In the control strain the immunohistochemical staining showed a very pronounced endothelial upregulation of ICAM-1 after the DSS treatment observed in areas of inflammatory infiltrate, especially in venules or arterioles of the propria and submucosa, and partly in the mesocolon. DSS-fed ICAM-1-deficient mice showed no endothelial enhancement and only faint staining of venules or capillaries approaching that encountered in the control ICAM-1-deficient animals. Our data indicate that ICAM-1 may play a crucial role in the development of acute intestinal inflammation, consistent with our finding that ICAM-1 deficiency can obviate severe forms of experimentally induced colitis in mice.

Analysis of cytokine production in the colon of nude mice with experimental colitis induced by adoptive transfer of immunocompetent cells from mice infected with a murine retrovirus

LP-BM5 murine leukemia virus (MuLV) is known to induce murine AIDS (MAIDS). We have shown that Sjögren's syndrome (SjS)-like exocrinopathy can be induced in mice with MAIDS and that adoptive transfer of spleen cells from MAIDS mice can induce inflammatory bowel disease-like colitis as well as SjS-like exocrinopathy in nude mice. To assess the role of interferon (IFN)-gamma and interleukin (IL)-10 in the pathogenesis of our experimental model, we tried to identify the cells producing these cytokines and their localization in the colitis lesions in situ. Expression of mRNA for IFN-gamma and IL-10 was assessed by RT-PCR, and protein expression of these cytokines was also analyzed in frozen sections of colon by double-color-staining immunofluorescence (IF). An increase of IFN-gamma and IL-10 mRNA was detected in the colon of mice with colitis, but not in that of control mice. Double-color IF showed that Mac-1(+) cells were positive for IFN-gamma or IL-10 and that most CD4(+) T cells were positive for IL-10, although the population of IFN-gamma-positive CD4(+) T cells was low. In our experimental colitis model, Mac-1(+) macrophages that produce both IFN-gamma and IL-10 might play a crucial role in the pathogenesis of colitis in combination with CD4(+) T cells.

Comparative studies of the colonic in situ expression of intercellular adhesion molecules (ICAM-1, -2, and -3), beta2 integrins (LFA-1, Mac-1, and p150,95), and PECAM-1 in ulcerative colitis and Crohn's disease

A dysregulated local immune defense with a constant influx of leukocytes provides a basis for continuous intestinal inflammation in ulcerative colitis (UC) and Crohn's disease (CD). Cell adhesion molecules are pivotal for the migration of leukocytes from the circulation toward the colonic epithelium. A study quantifying the cells expressing intercellular adhesion molecules (ICAMs), beta2 integrins, and platelet-endothelial cell adhesion molecule-1 (PECAM-1) in the colon was performed to illustrate the leukocyte migration pathway in inflammatory bowel disease. Serial colonic sections (10 UC, 10 CD, and 10 controls) were stained immunohistochemically for ICAM-1, ICAM-2, ICAM-3, CD11a, CD11b, CD18, and PECAM-1. Cell adhesion molecule expression was evaluated quantitatively with reference to topographic localization. In UC, polymorphonuclear leukocytes (PMNs) in contact with the crypt epithelium and in crypt abscesses expressed CD11b. CD tissue was characterized by CD11a-, CD11c-, and ICAM-1-expressing cells. ICAM-1 was detected on endothelial cells, leukocytes, and apical parts of epithelial membranes, whereas ICAM-2 was expressed on basal epithelial membranes. Most infiltrating leukocytes expressed ICAM-3, whereas perivascular mononuclear cells expressed PECAM-1. Interestingly, the epithelial basement membrane in UC stained for CD18. In conclusion, CD11b, CD18, and ICAM-2 seem to be important for PMN transepithelial migration in UC, whereas CD11a, CD11c, ICAM-1, and ICAM-3 seem central in leukocyte locomotion and aggregation in CD. Differentiated upregulation of cell adhesion molecules is suggested to be essential for the diversities between UC and CD.

Chemotactic properties of ICAM-1 and PECAM-1 on neutrophil granulocytes in ulcerative colitis: effects of prednisolone and mesalazine

BACKGROUND

ICAM-1 seems to exhibit effects other than passive leucocyte/endothelial interaction.

AIM

To investigate the attracting properties of selected adhesion molecules, assessing the influence of the two major anti-inflammatory drugs in ulcerative colitis, prednisolone and mesalazine.

METHODS

Circulating neutrophils (11 ulcerative colitis, 15 controls) were assessed in microchemotaxis chambers by the leading front technique, using physiologically relevant concentrations of ICAM-1 (0.005-5000 pM), PECAM-1 (0.001-1000 nM), and P-selectin (0.01-100 nM). Neutrophils pre-incubated with prednisolone (10(-8)-10(-4) M) or mesalazine (0.65-10. 4 nM) were assessed towards ICAM-1.

RESULTS

Migration of neutrophils towards ICAM-1 showed a bell-shaped curve with a maximum at 5 pM (migration: 37.7 microm; P<0.001), whereas PECAM-1 attracted neutrophils equally in the range of 0.1-10 nM (25.0 microm; P<0.001). P-selectin had no cell-attracting effect. No differences were detected between cells from ulcerative colitis patients and controls. Pre-treatment with prednisolone decreased the cell attracting effect of ICAM-1 in a dose-dependent manner to 72% of the basal migration (P<0.001). Conversely, prednisolone showed a pro-chemokinetic effect by increasing the spontaneous locomotion of neutrophils by 40% (P<0.001).

CONCLUSIONS

Specific chemotactic properties were observed for ICAM-1 and PECAM-1. Prednisolone exhibited a dual effect in inhibiting the ICAM-1-mediated migration and stimulating the general locomotion of neutrophils.

Changed colonic profile of P-selectin, platelet-endothelial cell adhesion molecule-1 (PECAM-1), intercellular adhesion molecule-1 (ICAM-1), ICAM-2, and ICAM-3 in inflammatory bowel disease

Cell adhesion molecules (CAM) are essential for the capture and migration of leucocytes. Ulcerative colitis (UC) and Crohn's disease (CD) are characterized by a continuous infiltration of leucocytes into intestinal tissue, and the colonic contents of P-selectin, PECAM-1, ICAM-1, ICAM-2, and ICAM-3 were therefore studied. Concentrations of these cell adhesion molecules were measured by an ELISA technique in sonicated colonic tissue from patients with UC and CD and controls with non-inflammatory disease and compared with the diagnosis and disease activity. P-selectin, PECAM-1, and ICAM-1 concentrations were elevated in UC patients compared with controls (P = 0.034, P = 0.014, P = 0.017, respectively), whereas that of ICAM-2 was not. The concentrations of these CAM did not differ in CD. In contrast, higher concentrations of ICAM-3 were found in the CD patients than in either UC (P = 0.001) or controls (P = 0.004). The CAM concentrations increased with disease activity, although only ICAM-1 was significantly elevated (P = 0.017). As considerable differences were found between UC and CD with comparable stages of inflammation, the mere presence of inflammation cannot solely explain the results. The observed differences in the CAM concentrations in UC and CD support the hypothesis that UC and CD are two distinct disease entities with separate pathogenic mechanisms.

Cytokine and endothelial cell adhesion molecule expression in interleukin-10-deficient mice

The objectives of this study were to quantify cytokine mRNA levels and endothelial cell adhesion molecule message and protein expression in healthy wild-type and interleukin-10-deficient (IL-10(-/-)) mice that develop spontaneous and chronic colitis. We found that colonic message levels of IL-1, IL-6, tumor necrosis factor-alpha, interferon-gamma, lymphotoxin-beta, and transforming growth factor-beta were elevated in colitic mice 10- to 35-fold compared with their healthy wild-type controls. In addition, colonic message levels of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) were found to be increased 10-, 5-, and 23-fold, respectively, in colitic IL-10(-/-) mice compared with their wild-type controls. Immunoradiolabeling as well as immunohistochemistry revealed large and significant increases in vascular surface expression of colonic ICAM-1, VCAM-1, and MAdCAM-1 in the mucosa as well as the submucosa of the colons of colitic mice. These data are consistent with the hypothesis that deletion of IL-10 results in the sustained production of proinflammatory cytokines, leading to the upregulation of adhesion molecules and infiltration of mononuclear and polymorphonuclear leukocytes into the cecal and colonic interstitium.

Nuclear factor-kappa B activity and intestinal inflammation in dextran sulphate sodium (DSS)-induced colitis in mice is suppressed by gliotoxin

In acute DSS-induced colitis nuclear factor (NF)-kappaB-dependent inflammatory cytokines including IL-1 and tumour necrosis factor-alpha (TNF-alpha) are up-regulated. Here we examined the effects of gliotoxin, a fungal metabolite known to inhibit NF-kappaB activity, on cytokine production by a mouse cell system in vitro and on intestinal inflammation and NF-kappaB activation in vivo. In vitro gliotoxin decreased TNF-alpha gene expression and protein production by RAW-264.7 mouse macrophage-like cells stimulated with lipopolysaccharide. In vivo, gliotoxin treatment of mice was begun on day 3 of 5% DSS application dissolved in the drinking water and continued until day 8. Gliotoxin treatment dose-dependently down-regulated colonic inflammation as assessed histologically and in parallel there was a suppression of colonic TNF-alpha and IL-1alpha mRNA expression on day 8 as analysed by semiquantitative reverse transcriptase-polymerase chain reaction (P < 0.01). Furthermore, colonic NF-kappaB DNA-binding activity was increased in DSS-induced colitis and was suppressed by gliotoxin. These results demonstrate the essential role of NF-kappaB in DSS-induced colitis and indicate a molecular approach to the treatment of intestinal inflammatory disorders.

The key role of macrophages in the immunopathogenesis of inflammatory bowel disease

Macrophages are important in the host's immunological and inflammatory responses. There is a large population of these cells in the normal intestinal mucosa where they represent the major antigen presenting cell population capable of determining the type of T cell responses that develop to luminal antigens. Studies suggest that the normal intestinal macrophages cannot be easily induced to mediate acute inflammatory responses. In active inflammatory bowel disease there is an increase in the mucosal macrophage population, derived from circulating monocytes. These recruited macrophages are phenotypically different from the resident population of cells and play a major role in mediating the chronic mucosal inflammation seen in patients with ulcerative colitis and Crohn's disease. They secrete many cytokines that are important in the proinflammatory responses, such as interleukin (IL)-1, IL-6, IL-8, IL-12, IL-18, and tumor necrosis factor-alpha. They also release reactive metabolites of oxygen and nitrogen and proteases that degrade the extracellular matrix. Macrophages also appear to be important during resolution of inflammation and repair of the intestinal mucosa that occurs during disease remission.

Down-regulation by bucillamine of lamina propria leucocytes in the rat colitis model

1. The efficacy of bucillamine has been reported in various inflammatory models. 2. In the present study, the effects of 2 weeks administration of bucillamine on hapten-induced experimental rat colitis were analysed. The gross morphological damage score was evaluated and the expression of CD4, CD8, CD11a, CD11b, CD25, CD54 and class II major histocompatibility complex (MHC) antigen was investigated by immunohistochemical methods. 3. Mean bodyweight was significantly increased in colitic rats given 750 micrograms bucillamine compared with colitic rats given vehicle (distilled water). Gross morphological damage was significantly less in colitic rats given 250 or 750 micrograms bucillamine compared with rats given vehicle. 4. Immunohistological studies revealed that CD4, CD11a, CD11b, CD54 and class II MHC antigen expression of infiltrating leucocytes was significantly lower in rat colonic mucosa treated with bucillamine. 5. From these findings, it appears that bucillamine may act through the down-regulation of the activation of lamina propria leucocytes in hapten-induced rat colitis.