Colitis in transgenic and knockout animals as models of human inflammatory bowel disease

Hyper α2,6-Sialylation Promotes CD4+ T-Cell Activation and Induces the Occurrence of Ulcerative Colitis

α2,6-sialylation, catalyzed by α2,6-sialyltransferase (ST6GAL1), plays a pivotal role in immune responses. However, the role of ST6GAL1 in the pathogenesis of ulcerative colitis (UC) remains unknown. ST6GAL1 mRNA is highly expressed in UC tissues compared with the corresponding adjacent normal tissues, and α2,6-sialylation is significantly increased in the colon tissues of patients with UC. The expression of ST6GAL1 and proinflammatory cytokines, such as interleukin (IL)-2, IL-6, IL-17, and interferon-gamma, is also increased. The number of CD4+ T cells increases in UC patients. St6gal1 gene knockout (St6gal1-/- ) rats are established by clustered regularly interspaced short palindromic repeats (CRISPR)-associated gene knockout system. St6gal1 deficiency reduces the levels of pro-inflammatory cytokines and alleviates colitis symptoms in UC model rats. Ablation of α2,6-sialylation inhibits the transport of the TCR to lipid rafts and suppresses CD4+ T-cell activation. The attenuation of TCR signaling downregulates the expression of NF-κB in ST6GAL1-/- CD4+ T-cells. Moreover, NF-κB could bind to the ST6GAL1 promoter to increase its transcription. Ablation of ST6GAL1 downregulates the expression of NF-κB and reduces the production of proinflammatory cytokines to relieve UC pathogenesis, which is a potential novel target for the clinical treatment of UC.

Tiliroside Ameliorates Ulcerative Colitis by Restoring the M1/M2 Macrophage Balance via the HIF-1α/glycolysis Pathway

Macrophages polarized to different phenotypes critically contribute to colitis development by coordinating inflammatory and anti-inflammatory processes. Herein, targeting the balance between the pro-inflammatory M1 and the anti-inflammatory M2 macrophage phenotypes can be a novel therapeutic approach for colitis. In the present study, we firstly demonstrated that tiliroside possessed the ability to alleviate the clinical symptoms of colitis as evidenced by decreased disease activity index (DAI) scores, longer colon length, reduced myeloperoxidase (MPO) activity, and improvement of colonic pathological damage in vivo. Furthermore, we showed that tiliroside modulated the balance between M1 and M2 macrophages toward a more anti-inflammatory status in colonic lamina propria but has little effect on the T cell population and epithelial barrier function in colitis mice. The macrophage depletion study further showed the protective effect of tiliroside was macrophage dependent in vivo. Mechanistically, our study demonstrated that tiliroside regulated cellular metabolism by inhibiting aerobic glycolysis in LPS and IFNγ stimulated macrophages. At the molecular level, tiliroside facilitated the proteasomal degradation of HIF-1α and downregulated mRNA expressions of HIF-1α dependent glycolytic enzymes in macrophages. Collectively, our data highlight the aberrant M1/M2 macrophage polarization in the initiation and development of ulcerative colitis and put forth the stage for considering tiliroside as a metabolic regulator in reprogramming macrophage polarization, which may serve as a promising therapeutic approach for treatment of inflammation-associated and metabolic disorders.

Recent updates on the basic mechanisms and pathogenesis of inflammatory bowel diseases in experimental animal models

The specific pathogenesis underlining inflammatory bowel disease (IBD) is very complicated, and it is further more difficult to clearly explain the pathophysiology of 2 major forms of IBD, Crohn’s disease (CD) and ulcerative colitis (UC), and both disorders affect individuals throughout life. Despite every extensive effort, the interplay among genetic factors, immunological factors, environmental factors and intestinal microbes is still completely unrevealed. Animal models are indispensable to find out mechanistic details that will facilitate better preclinical setting to target specific components involved in the pathogenesis of IBD. Based on many recent reports, dysbiosis of the commensal microbiota is implicated in the pathogenesis of several diseases, not only IBD but also colon cancer, obesity, psoriasis as well as allergic disorders, in both human and animal models. Advanced technologies including cell-specific and inducible knockout systems, which are recently employed to mouse IBD models, have further enhanced the ability of developing new therapeutic strategies for IBD. Furthermore, data from these mouse models highlight the critical involvement of dysregulated immune responses and impaired colonic epithelial defense system in the pathogenesis of IBD. In this review, we will explain from the history of animal models of IBD to the recent reports of the latest compounds, therapeutic strategies, and approaches tested on IBD animal models.

Effects of alternate-day fasting, time-restricted fasting and intermittent energy restriction DSS-induced on colitis and behavioral disorders

Intermittent fasting (IF) has been reported to have beneficial effects on improving gut function via lowering gut inflammation and altering the gut microbiome diversity. In this study, we aimed to investigate the differential effects of three different common IF treatments, alternate day fasting (ADF), time-restricted fasting (TRF), and intermittent energy restriction (IER), on a dextran sodium sulfate (DSS)-induced colitis mouse model. The results indicated that TRF and IER, but not ADF improved the survival rates of the colitis mice. TRF and IER, but not ADF, reversed the colitis pathological development by improving the gut barrier integrity and colon length. Importantly, TRF and IER suppressed the inflammatory responses and oxidative stress in colon tissues. Interestingly, TRF and IER also attenuated colitis-related anxiety-like and obsessive-compulsive disorder behavior and alleviated the neuroinflammation and oxidative stress. TRF and IER also altered the gut microbiota composition, including the decrease of the enrichments of colitis-related microbes such as Shigella and Escherichia Coli, and increase of the enrichments of anti-inflammatory-related microbes. TRF and IER also improved the short chain fatty acid formation in colitis mice. In conclusion, the TRF and IER but not ADF exhibited the protective effects against colitis and related behavioral disorders, which could be partly explained by improving the gut microbiome compositions and preventing gut leak, and consequently suppressing the inflammation and oxidative damages in both colon and brain. The current research indicates that proper IF regimens could be effective strategies for nutritional intervention for the prevention and treatment of colitis.

Bacterial Immunogenicity Is Critical for the Induction of Regulatory B Cells in Suppressing Inflammatory Immune Responses

B cells fulfill multifaceted functions that influence immune responses during health and disease. In autoimmune diseases, such as inflammatory bowel disease, multiple sclerosis and rheumatoid arthritis, depletion of functional B cells results in an aggravation of disease in humans and respective mouse models. This could be due to a lack of a pivotal B cell subpopulation: regulatory B cells (Bregs). Although Bregs represent only a small proportion of all immune cells, they exhibit critical properties in regulating immune responses, thus contributing to the maintenance of immune homeostasis in healthy individuals. In this study, we report that the induction of Bregs is differentially triggered by the immunogenicity of the host microbiota. In comparative experiments with low immunogenic Bacteroides vulgatus and strong immunogenic Escherichia coli, we found that the induction and longevity of Bregs depend on strong Toll-like receptor activation mediated by antigens of strong immunogenic commensals. The potent B cell stimulation via E. coli led to a pronounced expression of suppressive molecules on the B cell surface and an increased production of anti-inflammatory cytokines like interleukin-10. These bacteria-primed Bregs were capable of efficiently inhibiting the maturation and function of dendritic cells (DCs), preventing the proliferation and polarization of T helper (Th)1 and Th17 cells while simultaneously promoting Th2 cell differentiation in vitro. In addition, Bregs facilitated the development of regulatory T cells (Tregs) resulting in a possible feedback cooperation to establish immune homeostasis. Moreover, the colonization of germfree wild type mice with E. coli but not B. vulgatus significantly reduced intestinal inflammatory processes in dextran sulfate sodium (DSS)-induced colitis associated with an increase induction of immune suppressive Bregs. The quantity of Bregs directly correlated with the severity of inflammation. These findings may provide new insights and therapeutic approaches for B cell-controlled treatments of microbiota-driven autoimmune disease.

Gut microbiota-dependent modulation of innate immunity and lymph node remodeling affects cardiac allograft outcomes

We hypothesized that the gut microbiota influences survival of murine cardiac allografts through modulation of immunity. Antibiotic pretreated mice received vascularized cardiac allografts and fecal microbiota transfer (FMT), along with tacrolimus immunosuppression. FMT source samples were from normal, pregnant (immune suppressed), or spontaneously colitic (inflammation) mice. Bifidobacterium pseudolongum (B. pseudolongum) in pregnant FMT recipients was associated with prolonged allograft survival and lower inflammation and fibrosis, while normal or colitic FMT resulted in inferior survival and worse histology. Transfer of B. pseudolongum alone resulted in reduced inflammation and fibrosis. Stimulation of DC and macrophage lines with B. pseudolongum induced the antiinflammatory cytokine IL-10 and homeostatic chemokine CCL19 but induced lesser amounts of the proinflammatory cytokines TNFα and IL-6. In contrast, LPS and Desulfovibrio desulfuricans (D. desulfuricans), more abundant in colitic FMT, induced a more inflammatory cytokine response. Analysis of mesenteric and peripheral lymph node structure showed that B. pseudolongum gavage resulted in a higher laminin α4/α5 ratio in the lymph node cortical ridge, indicative of a suppressive environment, while D. desulfuricans resulted in a lower laminin α4/α5 ratio, supportive of inflammation. Discrete gut bacterial species alter immunity and may predict graft outcomes through stimulation of myeloid cells and shifts in lymph node structure and permissiveness.

The Proton-activated Receptor GPR4 Modulates Intestinal Inflammation

BACKGROUND AND AIMS

During active inflammation, intraluminal intestinal pH is decreased in patients with inflammatory bowel disease [IBD]. Acidic pH may play a role in IBD pathophysiology. Recently, proton-sensing G-protein coupled receptors were identified, including GPR4, OGR1 [GPR68], and TDAG8 [GPR65]. We investigated whether GPR4 is involved in intestinal inflammation.

METHODS

The role of GPR4 was assessed in murine colitis models by chronic dextran sulphate sodium [DSS] administration and by cross-breeding into an IL-10 deficient background for development of spontaneous colitis. Colitis severity was assessed by body weight, colonoscopy, colon length, histological score, cytokine mRNA expression, and myeloperoxidase [MPO] activity. In the spontaneous Il-10-/- colitis model, the incidence of rectal prolapse and characteristics of lamina propria leukocytes [LPLs] were analysed.

RESULTS

Gpr4-/- mice showed reduced body weight loss and histology score after induction of chronic DSS colitis. In Gpr4-/-/Il-10-/- double knock-outs, the onset and progression of rectal prolapse were significantly delayed and mitigated compared with Gpr4+/+/Il-10-/- mice. Double knock-out mice showed lower histology scores, MPO activity, CD4+ T helper cell infiltration, IFN-γ, iNOS, MCP-1 [CCL2], CXCL1, and CXCL2 expression compared with controls. In colon, GPR4 mRNA was detected in endothelial cells, some smooth muscle cells, and some macrophages.

CONCLUSIONS

Absence of GPR4 ameliorates colitis in IBD animal models, indicating an important regulatory role in mucosal inflammation, thus providing a new link between tissue pH and the immune system. Therapeutic inhibition of GPR4 may be beneficial for the treatment of IBD.

Visualization of IL-22-expressing Lymphocytes Using Reporter Mice

Reporter mice have been widely used to observe the localization of expression of targeted genes. This protocol focuses on a strategy to establish a new transgenic reporter mouse model. We chose to visualize interleukin (IL) 22 gene expression because this cytokine has important activities in the intestine, where it contributes to repair tissues damaged by inflammation. Reporter systems offer considerable advantages over other methods of identifying products in vivo. In the case of IL-22, other studies had first isolated cells from tissues and then re-stimulated the cells in vitro. IL-22, which is normally secreted, was trapped inside cells using a drug, and intracellular staining was used to visualize it. This method identifies cells capable of producing IL-22, but it does not determine whether they were doing so in vivo. The reporter design includes inserting a gene for a fluorescent protein (tdTomato) into the IL-22 gene in such a way that the fluorescent protein cannot be secreted and therefore remains trapped inside the producing cells in vivo. Fluorescent producers can then be visualized in tissue sections or by ex vivo analysis through flow cytometry. The actual construction process for the reporter included recombineering a bacterial artificial chromosome that contained the IL-22 gene. This engineered chromosome was then introduced into the mouse genome. Homeostatic IL-22 reporter expression was observed in different mouse tissues, including the spleen, thymus, lymph nodes, Peyer's patch, and intestine, by flow cytometry analysis. Colitis was induced by T-cell (CD4+CD45RBhigh) transfer, and reporter expression was visualized. Positive T cells were first present in the mesenteric lymph nodes, and then they accumulated inside the lamina propria of the distal small intestine and colon tissues. The strategy using BACs gave good-fidelity reporter expression compared to IL-22 expression, and it is simpler than knock-in procedures.

Gut microbial activity, implications for health and disease: the potential role of metabolite analysis

Microbial metabolism of proteins and amino acids by human gut bacteria generates a variety of compounds including phenol, indole, and sulfur compounds and branched chain fatty acids, many of which have been shown to elicit a toxic effect on the lumen. Bacterial fermentation of amino acids and proteins occurs mainly in the distal colon, a site that is often fraught with symptoms from disorders including ulcerative colitis (UC) and colorectal cancer (CRC). In contrast to carbohydrate metabolism by the gut microbiota, proteolysis is less extensively researched. Many metabolites are low molecular weight, volatile compounds. This review will summarize the use of analytical methods to detect and identify compounds in order to elucidate the relationship between specific dietary proteinaceous substrates, their corresponding metabolites, and implications for gastrointestinal health.

Probiotics for the treatment of inflammatory bowel disease

Probiotics are organisms which provide a desired and beneficial effect on human health. With recent evidence implicating a disruption in the balance of the gastrointestinal microbiome and intestinal immunity as a potential trigger for inflammatory bowel disease (IBD), there has been growing interest in using probiotics as an adjunct to standard anti-inflammatory and immune suppressing therapy. Animal models describe potential and plausible mechanisms of action for probiotics to counter inflammation of colonic mucosa. Although there are insufficient data to recommend probiotics in ulcerative colitis or Crohn's disease, good evidence supports the use of specific probiotics for maintenance of remission in pouchitis. Although there are limited regulatory standards for the agents, probiotics are relatively safe with minimal reported side effects or contraindications. More rigorous studies need to be published supporting efficacy and safety of these agents before they become a mainstay of IBD medical treatment.

Suppressive effect of berberine on experimental dextran sulfate sodium-induced colitis

The anti-inflammatory effect of berberine was evaluated in murine model of acute experimental colitis induced by dextran sulfate sodium (DSS). Berberine, given orally at 40, 20, 10 mg/kg for 10 days, ameliorated all the supposed inflammatory symptoms of the induced colitis, such as body weightloss, blood hemoglobin reduction, high myeloperoxidase levels, and malondialdehyde content-inflamed mucosa. Furthermore, the cytokine production of splenic lymphocytes was analyzed. The results showed the IFN-γ and IL-12 were increased, but IL-4 and IL-10 were decreased in DSS-induced colitis,when those were compared with the normal control. But the administration of berberine to DSS-induced colitis mice showed lower production of IFN-γ and IL-12 and higher production of IL-4 and IL-10 than the DSS-induced colitis mice. The results suggest that the protective effects of berberine against the DSS-induced colitis may be associated with the regulation of cytokine production.

Pharmacological Effects of Ba-Wei-Xi-Lei Powder on Ulcerative Colitis in Rats with Enema Application

Ba-Wei-Xi-Lei powder is a classical herbal mixture, and is widely used for the treatment of oral ulcer and ulcerative colitis. This study aimed to explore the effect of Ba-Wei-Xi-Lei powder with enema application on ulcerative colitis in rats. Ulcerative colitis was induced by immunization with rabbit's colonic mucosal protein emulsified with Completely Freund's Adjuvant. The mucosal inflammatory reaction and ulcer have been observed in the model rats. Characteristic changes of ulceractive colitis include that CD4 lymphocyte increased in peripheral blood while CD8 lymphocyte decreased; CD8 lymphocyte and TNF-α expression area increased in colonic mucosa, while CD4 lymphocyte decreased. Ba-Wei-Xi-Lei powder and sulfasalazine with enema application could alleviate the pathological changes in the model rats. The results suggest that the pharmacological effects of Ba-Wei-Xi-Lei powder on ulcerative colitis in rats are similar to the effect of sulfasalazine.

The membrane-bound mucin Muc1 regulates T helper 17-cell responses and colitis in mice

BACKGROUND & AIMS

T helper (Th) 17 cells produce the effector cytokine interleukin (IL)-17, along with IL-22, which stimulates colonic epithelial cells to produce a membrane-bound mucin, Muc1. Muc1 is a component of the colonic mucus, which functions as a lubricant and a physiologic barrier between luminal contents and mucosal surface. The gene MUC1 has been associated with susceptibility to inflammatory bowel disease; we investigated the role of Muc1 in development of colitis in mice.

METHODS

Muc1 and RAG1 were disrupted in mice (Muc/RAG double knockout mice); Th1-mediated colitis was induced by intravenous injection of CD4(+)CD45RB(high) T cells. We also studied Th2-mediated colitis using mice with disruptions in Muc1 and T-cell receptor α chain (Muc/TCR double knockout mice).

RESULTS

Muc1 deficiency led to the development of more severe forms of Th1- and Th2-induced colitis than controls. Loss of Muc1 increased colonic permeability and the Th17-cell, but not Th2 or Th1 cell, response in the inflamed colon. Loss of Muc1 also promoted expansion of an innate lymphoid cell population (Lin(-) ckit(-) Thy1(+) Sca1(+)) that produces IL-17. The expansion of Th17 adaptive immune cells and innate lymphoid cells required the commensal microbiota.

CONCLUSIONS

Muc1, which is up-regulated by Th17 signaling, functions in a negative feedback pathway that prevents an excessive Th17 cell response in inflamed colons of mice. Disruption of this negative feedback pathway, perhaps by variants in Muc1, might contribute to inflammatory bowel disease in patients.

Role of the commensal microbiota in normal and pathogenic host immune responses

The commensal microbiota that inhabit different parts of the gastrointestinal (GI) tract have been shaped by coevolution with the host species. The symbiotic relationship of the hundreds of microbial species with the host requires a tuned response that prevents host damage, e.g., inflammation, while tolerating the presence of the potentially beneficial microbes. Recent studies have begun to shed light on immunological processes that participate in maintenance of homeostasis with the microbiota and on how disturbance of host immunity or the microbial ecosystem can result in disease-provoking dysbiosis. Our growing appreciation of this delicate host-microbe relationship promises to influence our understanding of inflammatory diseases and infection by microbial pathogens and to provide new therapeutic opportunities.

Animal models of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory condition that is medicated by genetic, immune, and environmental factors. At least 66 different kinds of animal models have been established to study IBD, which are classified primarily into chemically induced, cell-transfer, congenial mutant, and genetically engineered models. These IBD models have provided significant contributions to not only dissect the mechanism but also develop novel therapeutic strategies for IBD. In addition, recent advances on genetically engineered techniques such as cell-specific and inducible knockout as well as knockin mouse systems have brought novel concepts on IBD pathogenesis to the fore. Further, mouse models, which lack some IBD susceptibility genes, have suggested more complicated mechanism of IBD than previously predicted. This chapter summarizes the distinct feature of each murine IBD model and discusses the previous and current lessons from the IBD models.

Decreased production of interleukin-10 and transforming growth factor-β in Toll-like receptor-activated intestinal B cells in SAMP1/Yit mice

A unique subset of B cells expressing interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) plays an essential role in preventing inflammation and autoimmunity. We investigated the presence of this cell subset in intestines and its role in the pathogenesis of ileitis using SAMP1/Yit and age-matched control AKR/J mice. Mononuclear cells were isolated from mesenteric lymph nodes (MLNs) and the expressions of B220, CD1d, CD5, Toll-like receptor 4 (TLR4) and TLR9 in isolated cells were analysed. Purified B cells were stimulated with lipopolysaccharide (LPS) or CpG-DNA, then IL-10 and TGF-β(1) expressions were examined by enzyme immunoassay and flow cytometry. Production of IL-1β by TLR-mediated macrophages co-cultured with or without purified MLN B cells from SAMP1/Yit and AKR/J mice was evaluated. In addition, interferon-γ (IFN-γ) production in intestinal T cells co-cultured with MLN B cells were also assessed in SAMP1/Yit and AKR/J strains. The production levels of IL-10 and TGF-β(1) stimulated by LPS and CpG-DNA were significantly lower in B cells separated from MLNs from the SAMP1/Yit strain. B cells expressing IL-10 and TGF-β(1) were mainly located in a population characterized by the cell surface marker CD1d(+) . Interleukin-1β production by TLR-activated macrophages co-cultured with MLN B cells from SAMP1/Yit mice was significantly higher than that of those from AKR/J mice. Interestingly, IFN-γ production by T cells was noted only when they were co-cultured with SAMP1/Yit but not the AKR/J B cells. These results are the first to show that disorders of regulatory B-cell function under innate immune activation may cause disease pathogenesis in a murine model of Crohn's disease.

Omega-3 polyunsaturated fatty acids ameliorate the severity of ileitis in the senescence accelerated mice (SAM)P1/Yit mice model

Clinical studies using omega-3 polyunsaturated fatty acids (omega3-PUFA) to Crohn's disease (CD) are conflicting. Beneficial effects of dietary omega3-PUFA intake in various experimental inflammatory bowel disease (IBD) models have been reported. However, animal models of large intestinal inflammation have been used in all previous studies, and the effect of omega3 fat in an animal model of small intestinal inflammation has not been reported. We hypothesized that the effects of omega3 fat are different between large and small intestine. The aim of this study was to determine whether the direct effect of omega3 fat is beneficial for small intestinal inflammation. Senescence accelerated mice (SAM)P1/Yit mice showed remarkable inflammation of the terminal ileum spontaneously. The numbers of F4/80-positive monocyte-macrophage cells as well as beta7-integrin-positive lymphocytes in the intestinal mucosa were increased significantly compared with those in the control mice (AKR-J mice). The area of mucosal addressin cell adhesion molecule-1 (MAdCAM-1)-positive vessels was also increased. The degree of expression levels of monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-6 and interferon (IFN)-gamma mRNA were increased significantly compared with those in the control mice. The feeding of two different kinds of omega3 fat (fish-oil-rich and perilla-oil-rich diets) for 16 weeks to SAMP1/Yit mice ameliorated inflammation of the terminal ileum significantly. In both the omega3-fat-rich diet groups, enhanced infiltration of F4/80-positive monocytes/macrophages in intestinal mucosa of SAMP1/Yit mice cells and the increased levels of MCP-1, IL-6 and IFN-gamma mRNA expression were ameliorated significantly compared with those in the control diet group. The results suggest that omega3 fat is beneficial for small intestinal inflammation by inhibition of monocyte recruitment to inflamed intestinal mucosa.

[Probiotics in gastrointestinal disorders]

Probiotics are preparations containing viable microorganisms that confer potential health benefits for the host. Alteration of bacterial flora both in terms of specific content and concentration may be beneficial in many gastrointestinal disorders. Probiotics are widely used for the management of these conditions in many countries. However, mechanisms of probiotics are incompletely understood. Benefits observed clinically with one species or combinations of species can not be generalized. The optimal dose of treatment has to be determined. Although probiotics are generally regarded safe, caution is needed when using these supplements routinely. It has been proved, that severe adverse events can occur as a complication of probiotic treatment. This review summarizes the recent knowledge concerning the use of probiotics in gastrointestinal disorders.

Multiparameter analysis of immunogenetic mechanisms in clinical diagnosis and management of inflammatory bowel disease

The integrity of the intestinal mucosa depends on a functional coordination of the epithelium, lumenal microorganisms, and the local immune system. The mammalian immune system is superbly organized for innate and adaptive recognition of microbial antigens, a defensive capacity that must be balanced against the tissue damage produced by immune activity to preserve normal intestinal function. Inflammatory bowel disease (IBD) is generally thought to reflect an impairment in this balance, due to a combination of host genetic traits that shift the balance of immune and epithelial function to commensal microbiota, and perhaps the composition or activity of certain microbial elements as well. There has been much progress defining the fundamental disorders of these host traits, immunologic processes, and microbial targets in inflammatory bowel disease. Other fields of clinical and geologic microbiology are teaching us about the dynamic interaction of commensal bacteria with their host environment. These lines of investigation have revealed not only important insights about inflammatory bowel disease (IBD) pathogenesis, but also defined technologies and tools useful for its diagnosis and clinical management. This review focuses on these advances at the translational interface. We will first consider the innate anti-microbial response, centering on the utility of NOD2 genotyping for predicting disease susceptibility, prognosis, and therapeutic response profile. We will then turn to the adaptive anti-microbial response, focusing on the application of antibodies to fungal and bacterial species and products for Crohn's disease (CD) diagnosis and prognosis, and immunogenetics of T cell immunosuppression management. Finally, we will describe autoimmune mechanisms in IBD, with particular attention to autoantibodies in IBD diagnosis and infliximab responsiveness. We will conclude with the concept of multiparameter analysis of patients, to refine patient characterization and stratification in diagnosis and clinical management.

The mucosal immune system at the gastrointestinal barrier

The immune system faces a considerable challenge in its efforts to maintain tissue homeostasis in the intestinal mucosa. It is constantly confronted with a large array of antigens, and has to prevent the dissemination and proliferation of potentially harmful agents while sparing the vital structures of the intestine from immune-mediated destruction. Complex interactions between the highly adapted effector cells and mechanisms of the innate and adaptive immune system generally prevent the luminal microflora from penetrating the intestinal mucosa and from spreading systemically. Non-haematopoietic cells critically contribute to the maintenance of local tissue homeostasis in an antigen-rich environment by producing protective factors (e.g. production of mucus by goblet cells, or secretion of microbicidal defensins by Paneth cells) and also through interactions with the adaptive and innate immune system (such as the production of chemotactic factors that lead to the selective recruitment of immune cell subsets). The complexity of the regulatory mechanisms that control the local immune response to luminal antigens is also reflected in the observation that mutations in immunologically relevant genes often lead to the development of uncontrolled inflammatory reactions in the microbially colonized intestine of experimental animals.

IL-22 ameliorates intestinal inflammation in a mouse model of ulcerative colitis

Expression of IL-22 is induced in several human inflammatory conditions, including inflammatory bowel disease (IBD). Expression of the IL-22 receptor is restricted to innate immune cells; however, the role of IL-22 in colitis has not yet been defined. We developed what we believe to be a novel microinjection-based local gene-delivery system that is capable of targeting the inflamed intestine. Using this approach, we demonstrated a therapeutic potency for IL-22-mediated activation of the innate immune pathway in a mouse model of Th2-mediated colitis that induces disease with characteristics similar to that of IBD ulcerative colitis (UC). IL-22 gene delivery enhanced STAT3 activation specifically within colonic epithelial cells and induced both STAT3-dependent expression of mucus-associated molecules and restitution of mucus-producing goblet cells. Importantly, IL-22 gene delivery led to rapid amelioration of local intestinal inflammation. The amelioration of disease by IL-22 was mediated by enhanced mucus production. In addition, local gene delivery was used to inhibit IL-22 activity through overexpression of IL-22-binding protein. Treatment with IL-22-binding protein suppressed goblet cell restitution during the recovery phase of a dextran sulfate sodium-induced model of acute colitis. These data demonstrate what we believe to be a novel function for IL-22 in the intestine and suggest the potency of a local IL-22 gene-delivery system for treating UC.

In vivo biomarkers for targeting colorectal neoplasms

Colorectal carcinoma continues to be a leading cause of cancer morbidity and mortality despite widespread adoption of screening methods. Targeted detection and therapy using recent advances in our knowledge of in vivo cancer biomarkers promise to significantly improve methods for early detection, risk stratification, and therapeutic intervention. The behavior of molecular targets in transformed tissues is being comprehensively assessed using new techniques of gene expression profiling and high throughput analyses. The identification of promising targets is stimulating the development of novel molecular probes, including significant progress in the field of activatable and peptide probes. These probes are being evaluated in small animal models of colorectal neoplasia and recently in the clinic. Furthermore, innovations in optical imaging instrumentation are resulting in the scaling down of size for endoscope compatibility. Advances in target identification, probe development, and novel instruments are progressing rapidly, and the integration of these technologies has a promising future in molecular medicine.

Apoptosis Inhibitor Expressed by Macrophages Tempers Autoimmune Colitis and the Risk of Colitis-Based Carcinogenesis in TCRα−/− Mice

BACKGROUND

Crohn's disease and ulcerative colitis (UC) are the two main entities involved in human inflammatory bowel disease (IBD). However, their precise etiologies remain unclear. To study the development of mucosal inflammation, and chronic inflammation-based dysplasia and carcinoma formation, we examined possible roles of the apoptosis inhibitor expressed by macrophages (AIM) in an experimental IBD model.

METHODS

In this study, we used T cell receptor alpha deficient (TCRalpha(-/-)) mice, a known UC-like colitis model. We generated TCRalpha(-/-) x AIM(-/-) double knockout mice by crossbreeding TCRalpha(-/-) with AIM(-/-) mice. At 24 weeks of age, mice were killed to obtain colon tissues for pathological examinations. TCRalpha(-/-) x AIM(+/-) mice, heterozygous littermates of TCRalpha(-/-) x AIM(-/-) mice, were used as controls.

RESULTS

Severe colitis was observed in TCRalpha(-/-) x AIM(-/-) mice, when compared with TCRalpha(-/-) x AIM(+/-) mice. Dysplasia was detected in TCRalpha(-/-) x AIM(-/-) mice, but not in TCRalpha(-/-) x AIM(+/-) mice. Adenocarcinoma formation was observed from dysplasia only in TCRalpha(-/-) x AIM(-/-) mice.

CONCLUSION

Not only a high incidence of severe colitis but also dysplasia and adenocarcinoma formation were observed in TCRalpha(-/-) x AIM(-/-) mice only. AIM have some regulatory roles in inflammation and progression of dysplasia to carcinoma in TCRalpha(-/-) mice.

Inducible IL-12-producing B cells regulate Th2-mediated intestinal inflammation

BACKGROUND & AIMS

Our previous studies have identified a B-cell subset that is induced under inflammatory conditions in T-cell receptor alpha knockout (TCRalphaKO) mice and contributes to the attenuation of colitis by producing interleukin (IL)-10. However, it is unclear whether IL-10-producing B cells directly or indirectly regulate inflammation.

METHODS

Cytokine production of purified mesenteric lymph node (MLN) B cells was examined by flow cytometric analysis, enzyme-linked immunosorbent assay, quantitative polymerase chain reaction, and RNase protection assay. To investigate the functional role of IL-12p70 in the pathogenesis of colitis in TCRalphaKO mice, IL-12p35-deficient TCRalpha double knockout mice were generated.

RESULTS

In the absence of B cells or IL-10, IL-12p35 expression was significantly down-regulated in the MLN of TCRalphaKO mice. The expression of IL-12p35 was restored in the recipient B-cell-deficient TCRalpha double knockout (alphamicroDKO) mice by the transfer of B cells capable of producing IL-10. Notably, B cells predominantly produced IL-12p35 in the MLN through the help of IL-10-producing B cells. Functionally, IL-12 is involved in the regulation of the T-helper (Th) 2-mediated inflammation as indicated by the development of much more severe colitis in IL-12p35-deficient TCRalpha double knockout (alphap35DKO) mice compared with TCRalphaKO mice. In addition, transfer of MLN B cells from TCRalphaKO mice but not from alphap35DKO mice suppressed colitis in recipient alphamicroDKO mice.

CONCLUSIONS

These studies have identified a novel IL-12-producing regulatory B-cell subset that develops under Th2-mediated intestinal inflammatory conditions and in the presence of IL-10 and is involved in the regulation of intestinal inflammation.

SOCS proteins, cytokine signalling and immune regulation

Suppressor of cytokine signalling (SOCS) proteins are inhibitors of cytokine signalling pathways. Studies have shown that SOCS proteins are key physiological regulators of both innate and adaptive immunity. These molecules positively and negatively regulate macrophage and dendritic-cell activation and are essential for T-cell development and differentiation. Evidence is also emerging of the involvement of SOCS proteins in diseases of the immune system. In this Review we bring together data from recent studies on SOCS proteins and their role in immunity, and propose a cohesive model of how cytokine signalling regulates immune-cell function.

Immunomodulatory effects of (n-3) fatty acids: putative link to inflammation and colon cancer

Chronic inflammation and colorectal cancer are closely linked. Although the overall mechanisms of inflammation-associated gastrointestinal carcinogenesis are complex, it is clear that antiinflammatory therapy is efficacious against neoplastic progression and malignant conversion. From a dietary perspective, fish oil containing (n-3) polyunsaturated fatty acids (PUFAs) has antiinflammatory properties, but for years the mechanism has remained obscure. Of relevance to the immune system in the intestine, we showed that (n-3) PUFA feeding alters the balance between CD4+ T-helper (Th1 and Th2) subsets by directly suppressing Th1 cell development (i.e., clonal expansion). This is noteworthy because Th1 cells mediate inflammatory diseases and resistance to intracellular pathogens or allergic hypersensitivity, and Th2 cells mediate resistance to extracellular pathogens. Therefore, any changes induced by (n-3) PUFAs in T-cell subset balance and function are important because the outcome is expected to suppress the development of autoimmune diseases and possibly the occurrence of colon cancer. Precisely how the immunomodulatory effects of (n-3) PUFAs influence inflammation-associated colonic tumor development is the subject of an ongoing investigation.

Dependence of intestinal granuloma formation on unique myeloid DC-like cells

Granulomas represent a localized inflammatory reaction that is characteristically observed in many inflammatory conditions. However, the mechanisms of granuloma formation have not been fully defined. Herein we demonstrate, by using experimental models of intestinal inflammation, that a unique CD11c+ DC-like cell subset that exhibits phenotypic and functional features of immature myeloid DCs and is characterized by the expression of a macrophage marker (F4/80) produces large amounts of IL-23 and directly induces the development of granulomas under a Th1-predominant intestinal inflammatory condition. Importantly, both IL-4 and IgG contribute to the suppression of F4/80+ DC-like cell-mediated granuloma formation by regulating the function and differentiation of this cell subset. In addition, enteric flora is required for the F4/80+ DC-like cell-mediated granuloma formation. Collectively, our data provide what we believe are novel insights into the involvement of F4/80+ DC-like cells in intestinal granuloma formation and demonstrate the role of host (IL-4 and IgG) and environmental (enteric flora) factors that regulate this function.

Evaluation of Th1-like, Th2-like and immunomodulatory cytokine mRNA expression in the skin of dogs with immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis

The term immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis (ImR-LPP) has previously been proposed to denote a subpopulation of dogs with idiopathic pododermatitis. The objective of this study was to quantify the expression of mRNA encoding Th(1)-like [interferon (IFN)-gamma, interleukin (IL)-2 and IL-12], Th(2)-like [IL-4 and IL-6] and immunomodulatory cytokines [IL-10 and transforming growth factor (TGF)-beta] in lesional ImR-LPP, nonlesional ImR-LPP and healthy control pedal skin. Gene transcripts were quantified using TaqMan real-time reverse transcriptase-polymerase chain reaction assays. The skin of dogs with ImR-LPP had significant overexpression of IL-6 mRNA (P < 0.05) and significant underexpression of IL-12 mRNA (P < 0.01) compared to healthy controls. In addition, lesional ImR-LPP skin had significantly higher levels of IL-10 transcripts compared to healthy control pedal skin (P < 0.05). Although not attaining significance (P = 0.07), a trend towards reduced TGF-beta mRNA expression in lesional ImR-LPP skin was also evident. There were no significant differences in the levels of IFN-gamma or IL-2 mRNA transcripts among the three skin sample sources. IL-4 mRNA was detected in only one lesional sample. These results suggest that the pathogenesis of ImR-LPP may be associated with a T-cell-mediated inflammatory response characterized by impaired Th(1)-like, but enhanced Th(2)-like cytokine expression.

Is the sugar always sweet in intestinal inflammation?

Immune responses are mediated mainly by protein/protein interactions. In addition, protein/carbohydrate (sugar) interactions through specific protein families termed lectin and chi-lectin are also involved in several immune and biological responses under not only the state of health but also inflammatory conditions. Interestingly, recent studies have identified unexpected roles of animal lectins (galectin-1 and galectin-4) and chi-lectin (chitinase 3-like-1) in intestinal inflammation. Galectin-1 contributes to the suppression of intestinal inflammation by the induction of effector T cell apoptosis. In contrast, galectin-4 is involved in the exacerbation of this inflammation by specifically stimulating intestinal CD4+ T cells to produce IL-6. CHI3L1 enhances the host/microbial interaction that leads to the exacerbation of intestinal inflammation. In this review, we discuss a novel aspect of lectin/carbohydrate interactions in intestinal inflammation.

Escherichia coli strain Nissle 1917 ameliorates experimental colitis via toll-like receptor 2- and toll-like receptor 4-dependent pathways

Toll-like receptors (TLRs) are key components of the innate immune system that trigger antimicrobial host defense responses. The aim of the present study was to analyze the effects of probiotic Escherichia coli Nissle strain 1917 in experimental colitis induced in TLR-2 and TLR-4 knockout mice. Colitis was induced in wild-type (wt), TLR-2 knockout, and TLR-4 knockout mice via administration of 5% dextran sodium sulfate (DSS). Mice were treated with either 0.9% NaCl or 10(7) E. coli Nissle 1917 twice daily, followed by the determination of disease activity, mucosal damage, and cytokine secretion. wt and TLR-2 knockout mice exposed to DSS developed acute colitis, whereas TLR-4 knockout mice developed significantly less inflammation. In wt mice, but not TLR-2 or TLR-4 knockout mice, E. coli Nissle 1917 ameliorated colitis and decreased proinflammatory cytokine secretion. In TLR-2 knockout mice a selective reduction of gamma interferon secretion was observed after E. coli Nissle 1917 treatment. In TLR-4 knockout mice, cytokine secretion was almost undetectable and not modulated by E. coli Nissle 1917, indicating that TLR-4 knockout mice do not develop colitis similar to the wt mice. Coculture of E. coli Nissle 1917 and human T cells increased TLR-2 and TLR-4 protein expression in T cells and increased NF-kappaB activity via TLR-2 and TLR-4. In conclusion, our data provide evidence that E. coli Nissle 1917 ameliorates experimental induced colitis in mice via TLR-2- and TLR-4-dependent pathways.

A defect in epithelial barrier integrity is not required for a systemic response to bacterial antigens or intestinal injury in T cell receptor-alpha gene-deficient mice

BACKGROUND AND AIMS

Genetically induced disruption of the intestinal epithelial barrier leads to development of intestinal inflammation. In the interleukin-10 gene-deficient inflammatory bowel disease (IBD) mouse model, for instance, a primary defect in intestinal epithelial integrity occurs before the development of enterocolitis. In humans, a causal role for epithelial barrier disruption is still controversial. Although studies with first-degree relatives of IBD patients suggests an underlying role of impaired barrier function, a primary epithelial barrier defect in IBD patients has not been confirmed. The purpose of this article is to examine whether a primary epithelial barrier disruption is a prerequisite for the development of intestinal inflammation or whether intestinal inflammation can develop in the absence of epithelial disruption. We examined the intestinal epithelial integrity of the T cell receptor (TCR)-alpha gene-deficient mouse model of IBD.

MATERIALS AND METHODS

In vivo colonic permeability, determined by mannitol transmural flux, was assessed in 6-week-, 12-week-, and 25-week-old TCR-alpha gene-deficient and wild-type control mice using a single-pass perfusion technique. Mice were scored for intestinal histological injury and intestinal cytokine levels measured in organ cultures. Systemic responses to bacterial antigens were determined through 48-h spleen cell cultures stimulated with sonicate derived from endogenous bacterial strains.

RESULTS

In contrast with previous findings in the interleukin-10 gene-deficient IBD model, TCR-alpha gene-deficient mice did not demonstrate evidence of primary intestinal epithelial barrier disruption at any age, despite developing a moderate to severe colitis within 12 weeks. A rise in intestinal interferon (IFN)-gamma levels preceded the onset of mucosal inflammation and then correlated closely with the degree of intestinal inflammation and injury. Spleen cells from TCR-alpha gene-deficient mice released IFN-gamma in response to stimulation with endogenous luminal bacterial antigens, a finding that suggests that the systemic response to bacterial antigens occurred independently of epithelial barrier disruption.

CONCLUSIONS

Intestinal inflammation and a systemic response to bacterial antigens can develop in the absence of a measurable disruption of intestinal permeability.

Elevated serum anti-I2 and anti-OmpW antibody levels in children with IBD

BACKGROUND

Bacteria are implicated as important factors in the pathogenesis of inflammatory bowel disease (IBD). The aim of this study was to seek evidence of possible bacterial targets of the immune response related to IBD in children.

METHODS

Seventy-eight children referred to the Department of Paediatrics at Tampere University Hospital on suspicion of IBD were included in the study. Upper and lower gastrointestinal endoscopies with biopsies were performed on all children. Sera from 75 children were tested for antibodies to the Pseudomonas fluorescens-associated sequence I2, a Bacteroides caccae TonB-linked outer membrane protein, OmpW, anti-Saccharomyces cerevisiae, and perinuclear anti-neutrophil cytoplasmic antibodies.

RESULTS

The IBD diagnosis was confirmed in 35 children (18 with Crohn's disease [CD], 12 with ulcerative colitis [UC], and 5 with indeterminate colitis [IC]); 43 children were found to have no inflammation in the gut. Forty-three percent (15 of 35) of those with IBD evinced positive seroreactivity to I2 and 46% (16 of 35) to OmpW. In CD, seroreactivity to I2 and OmpW was 50% (9 of 18) and 61% (11 of 18), respectively. Serum anti-I2 and anti-OmpW immunoglobulin A levels were significantly elevated in children with CD in comparison with the non-IBD group (P = 0.007 and P = 0.001, respectively). A combination of OmpW, I2, and anti-S cerevisiae tests identified 94% of CD patients, and a combination of OmpW, I2, and perinuclear anti-neutrophil cytoplasmic antibodies detected 83% of UC cases.

CONCLUSIONS

Among children with IBD, strong serological responses to microbial antigens can be found, suggesting that P fluorescens and B caccae antigens have a potential role in the microbiology and immunology of the disease. Furthermore, serologic reactivity to the set of antigens studied here seems to be applicable in the initial differential diagnosis of children with CD and UC.

A Case for Regulatory B Cells

B cells are typically characterized by their ability to produce Abs, including autoantibodies. However, B cells possess additional immune functions, including the production of cytokines and the ability to function as a secondary APC. As with T cells, the B cell population contains functionally distinct subsets capable of performing both pathogenic and regulatory functions. Recent studies indicate that regulatory B cells develop in several murine models of chronic inflammation, including inflammatory bowel disease, rheumatoid arthritis, and experimental autoimmune encephalomyelitis. The regulatory function may be directly accomplished by the production of regulatory cytokines IL-10 and TGF-beta and/or by the ability of B cells to interact with pathogenic T cells to dampen harmful immune responses. In this review, we make a case for the existence of regulatory B cells and discuss the possible developmental pathways and functional mechanisms of these B cells.

Experimental models of inflammatory bowel disease reveal innate, adaptive, and regulatory mechanisms of host dialogue with the microbiota

There are now many experimental models of inflammatory bowel disease (IBD), most of which are due to induced mutations in mice that result in an impaired homeostasis with the intestinal microbiota. These models can be clustered into several broad categories that, in turn, define the crucial cellular and molecular mechanisms of host microbial interactions in the intestine. The first of these components is innate immunity defined broadly to include both myeloid and epithelial cell mechanisms. A second component is the effector response of the adaptive immune system, which, in most instances, comprises the CD4+ T cell and its relevant cytokines. The third component is regulation, which can involve multiple cell types, but again particularly involves CD4+ T cells. Severe impairment of a single component can result in disease, but many models demonstrate milder defects in more than one component. The same is true for both spontaneous models of IBD, C3H/HeJBir and SAMPI/Yit mice. The thesis is advanced that 'multiple hits' or defects in these interacting components is required for IBD to occur in both mouse and human.

Therapeutic targeting of alpha 4-integrins in chronic inflammatory diseases: tipping the scales of risk towards benefit?

Inhibition of leukocyte trafficking via alpha4-integrin antibody blockade has recently become a validated therapeutic approach for several inflammatory diseases, including multiple sclerosis, ulcerative colitis and Crohn's disease. In the midst of this recent success, 3 patients receiving chronic treatment with the anti-alpha4 antagonist natalizumab (Tysabri) for the treatment of multiple sclerosis or Crohn's disease, developed JC-virus related progressive multifocal leukoencephalopathy (PML). These unforeseen consequences suggest that long term blockade of alpha4-integrins might prevent trafficking of non-pathogenic lymphocytes that are essential for viral immunosurveillance. In the current issue of the European Journal of Immunology Bjursten and colleagues report that long term treatment with anti-alpha4-integrin antibodies results in exacerbation of the murine model of colitis induced by the targeted deletion of the heterotrimeric G protein subunit Galphai2. In order to properly evaluate the efficacy and safety of anti-alpha4-integrin therapy, the relationship between these observations in an immunologically altered animal model and human clinical disease needs to be carefully measured.

Appendix is a priming site in the development of ulcerative colitis

AIM: The role of the appendix has been highlighted in the pathogenesis of ulcerative colitis (UC). The aims of this study were to elucidate the immuno-imbalances in the appendix of UC patients, and to clarify the role of the appendix in the development of UC.

METHODS: Colonoscopic biopsy specimens of the appendix, transverse colon, and rectum were obtained from 86 patients with UC: active pancolitis (A-Pan; n = 15), active left-sided colitis (A-Lt; n = 25), A-Lt with appendiceal involvement (A-Lt/Ap; n = 10), inactive pancolitis (I-Pan; n = 14), and inactive left-sided colitis (I-Lt; n = 22), and from controls. In the isolated mucosal T cells, the CD4/CD8 ratio and proportion of activated CD4+ T cells were investigated, and compared with controls.

RESULTS: In the appendix, the CD4/CD8 ratio significantly increased in A-Lt and A-Lt/Ap. The ratio in the appendix also tended to increase in A-Pan. In the rectum, the ratio significantly increased in all UC groups. In the appendix, the proportion of CD4+CD69+ (early activation antigen) T cells significantly increased in all UC groups. In the rectum, the proportion of CD4+CD69+ T cells significantly increased only in A-Pan. The proportion of CD4+HLA-DR+ (mature activation antigen) T cells significantly increased only in the rectum of A-Pan, but not in the other areas of any groups.

CONCLUSION: The increased CD4/CD8 ratio and predominant infiltration of CD4+CD69+ T cells in the appendix suggest that the appendix is a priming site in the development of UC.

Epithelial dysfunction associated with the development of colitis in conventionally housed mdr1a-/- mice

P-glycoprotein, the product of the multidrug resistance protein 1 (MDR1) gene, is a xenobiotic transporter that may contribute to the physiology of the intestinal barrier. Twenty-five percent of mdr1a-deficient (mdr1a(-/-)) mice spontaneously develop colitis at variable ages when maintained under specific pathogen-free conditions. We hypothesized that this disease would result from epithelial dysfunction and that conventional housing would increase incidence and severity of the colitis phenotype. Wild-type congenic FVB (+/+) mice were maintained under the same conditions as controls. Knockout and wild-type mice were matched for age and gender and observed for signs of colitis. Colonic tissues from both groups of mice were examined for macroscopic and microscopic injury and for basal ion transport and transepithelial resistance (TER). Translocation of bacteria across the intestine was assessed by culturing the spleen and mesenteric lymph nodes. Protein analysis was performed by Western blot analysis. All mdr1a(-/-) mice developed weight loss and signs of colitis, whereas wild-type mice never showed such signs. Within the mdr1a(-/-) group, males consistently developed severe colitis earlier than females. Knockout mice showed increased basal colonic ion transport (females, 162.7 +/- 4.6 vs. 49.7 +/- 3.8 muA/cm(2); males, 172.6 +/- 5.6 vs. 54.2 +/- 3.1 muA/cm(2); P < 0.01) and decreased TER (females, 25.4 +/- 0.3 vs. 36.4 +/- 0.8 Omega.cm(2); males, 23.1 +/- 1.0 vs. 38.3 +/- 0.2 Omega.cm(2); P < 0.01) compared with wild-type mice. Barrier dysfunction was accompanied by decreased phosphorylation of tight junction proteins. Expression of cyclooxygenase-2 and inducible nitric oxide synthase in intestinal tissues was increased in the mdr1a(-/-) group (P < 0.01) and correlated with disease severity. Bacterial translocation was greater both in incidence (P < 0.01) and severity (P < 0.001) for the knockout group. With respect to all indexes studied, mdr1a(-/-) males performed worse than females. Our data support the hypothesis that alterations in the intestinal barrier alone, in the absence of immune dysfunction, may rapidly lead to colitis in the setting of a normal colonic flora.

Development and validation of a novel IL-10 deficient cell transfer model for colitis

A number of rodent models for inflammatory bowel disease (IBD) have been developed, but most cannot be used to develop and validate new therapies for IBD. From the models developed, the IL-10 deficient mouse model is the one that results in a disease similar to human IBD; however, in this model, colitis occurs with variable incidence taking 3-4 months to develop. These are serious problems with the model when evaluating a new therapy because of the large-scale experiments required and the difficulty in performing an accurate pharmacological analysis. In this study, the IL-10 deficient mouse model was modified by transferring whole spleen and mesenteric lymph node cells from IL-10 deficient mice to CB-17 SCID mice. In this IL-10 deficient cell transfer model, chronic intestinal inflammation developed in all recipients within 2-3 weeks, which was far earlier than in donor IL-10 deficient mice. The pathological phenotypes were similar to those of IL-10 deficient mice and CD45RBhi T cell-transfer models. In addition, we assessed several agents for inflammatory bowel disease to validate the general utility of this cell transfer model. It is worth noting that TNFR-Ig or prednisolone, which is effective for treatment of patients with severe-fulminant Crohn's disease, markedly attenuated pathological clinical indices in this colitis model, whereas the immunosuppressive agents, azathioprine, tacrolimus, and cyclosporine A produced no significant effect. These results suggest that the IL-10 deficient cell transfer model is a good experimental model to use for developing new and effective therapies for active IBD.

Th response to Helicobacter pylori differs between patients with gastric ulcer and duodenal ulcer

OBJECTIVE

Helicobacter pylori (H. pylori) infection induces both gastric (GU) and duodenal ulcers (DU). We examined whether host immunological response to H. pylori determines different disease outcomes.

MATERIAL AND METHODS

Thirty-two GU and 28 DU patients infected with H. pylori, and 24 dyspeptic patients without infection were enrolled. The constituents of cellular infiltrates in biopsies from each patient were determined and lymphokines secreted by stimulated T cells were measured. Serum concentrations of IgG subclasses specific to H. pylori were measured.

RESULTS

Low pepsinogen I and high pepsinogen II levels were observed in GU patients, while a high pepsinogen I level was found in DU patients. T cells predominate over other cell types in both GU and DU patients. GU patients had a higher number of T cells (p < 0.01) and lower plasma cells (p < 0.05) than those in DU patients. T cells from GU patients produced greater amounts of IFN-gamma and less IL-4 than those in DU patients (p < 0.01). GU patients had a higher serum level of IgG2 specific to H. pylori than that in DU patients (p < 0.01).

CONCLUSIONS

Th response by gastric T cells in GU patient was more polarized to Th1 as compared with that in DU patients, suggesting that a distinct immune response to H. pylori induces different disease outcomes.

Animal models of inflammatory bowel disease

In inflammatory bowel disease (IBD), experimental models have proven to be important tools for detecting potential therapeutic agents and for investigating the mechanisms of pathogenesis. This review is intended to cover recent advances in basic IBD model applications. The use of more than 20 animal models has allowed the detection of numerous protective pharmacological agents, including a number of immunomodulatory agents that have entered the therapeutic armamentarium. The models have been classified into five main categories based on the methods of induction: gene knockout (KO), transgenic, chemical, adoptive transfer, and spontaneous (each with subcategories).

IL-8 is a key chemokine regulating neutrophil recruitment in a new mouse model of Shigella-induced colitis

The lack of a mouse model of acute rectocolitis mimicking human bacillary dysentery in the presence of invasive Shigella is a major handicap to study the pathogenesis of the disease and to develop a Shigella vaccine. The inability of the mouse intestinal mucosa to elicit an inflammatory infiltrate composed primarily of polymorphonuclear leukocytes (PMN) may be due to a defect in epithelial invasion, in the sensing of invading bacteria, or in the effector mechanisms that recruit the PMN infiltrate. We demonstrate that the BALB/cJ mouse colonic epithelium not only can be invaded by Shigella, but also elicits an inflammatory infiltrate that, however, lacks PMN. This observation points to a major defect of mice in effector mechanisms, particularly the lack of expression of the CXC chemokine, IL-8. Indeed, this work demonstrates that the delivery of recombinant human IL-8, together with Shigella infection of the colonic epithelial surface, causes an acute colitis characterized by a strong PMN infiltrate that, by all criteria, including transcription profiles of key mediators of the innate/inflammatory response and histopathological lesions, mimics bacillary dysentery. This is a major step forward in the development of a murine model of bacillary dysentery.

STAT3 activation in macrophages following infection with Salmonella

The induction of signal transducer and activators of transcription (STATs) in macrophages is necessary for cellular activation, and we investigated the activation of STAT3 in these cells following infection with Salmonella. Increased activation of STAT3 was observed at 6 and 24 h post-infection in the mesenteric lymph nodes and spleens when compared to control mice. CD11b+ cells isolated from the mesenteric lymph nodes of infected mice demonstrated increased STAT3 activation as early as 6 h following infection. Culturing bone marrow-derived macrophages with Salmonella resulted in translocation of STAT3 to the nucleus and STAT3 phosphorylation as early as 30 min post-exposure. Increased STAT3 activation was also observed in the lymphoid organs or in macrophages from mice deficient for IL-6 or IL-10 production following infection. Taken together, these studies clearly demonstrate an early increase in the activation of STAT3 in vivo and in vitro following infection with wild type Salmonella.

Review article: gut flora and inflammatory bowel disease

The pathogenesis of inflammatory bowel disease involves interactions between the host susceptibility, mucosal immunity and intestinal microflora. There is therefore great interest in the changes in the endogenous flora in inflammatory bowel disease patients and in the establishment of potential genetic variations in host responses to endogenous bacteria. In this review, we summarize the modifications in the various regional ecosystems in the gastrointestinal tract during inflammatory bowel disease (luminal bacteria in faeces or inside the gastrointestinal tract, bacteria in mucus and bacteria directly attached to the mucosa). Results were obtained following a 'candidate microorganism strategy' and, as is occurring increasingly frequently, following a 'full description strategy', which has progressed largely due to the development of culture-independent techniques. The possibility of modifying the ecosystem using prebiotics or probiotics offers hope for new treatment developments, particularly in the prevention of relapse.

MHC-bound antigens and proteomics for novel target discovery

The MHC molecules present normal as well as disease-related and pathogen-derived peptides to T cells as a way of alerting the immune system of the health status of a cell. Proteomic technologies involving immunoaffinity purification are now extensively used to separate MHC complexes from their peptide cargo, and then the petides are sequenced by tandem mass spectrometry. The identified peptides are tested as vaccine candidates for viral diseases, immunostimulants for treating cancer, and immune-tolerance-inducing agents for autoimmune disorders. One of the challenges in devising novel HLA-peptide-based immunotherapies is to decipher whether a therapeutic window exists between the induction of tumor immunity and the onset of autoimmunity, which can have dangerous sequelae. This review will cover these topics with an overview of the vast possibilities emerging in the field of proteomic analyses of MHC-bound antigens as novel targets for immunotherapy.