细胞因子在炎症性肠病中的作用

炎症性肠病(inflammatory bowel disease,IBD)是一组病因未明的以慢性胃肠道炎症为特征的疾病,包括克罗恩病(Crohn's disease,CD)和溃疡性结肠炎(ulcerative colitis,UC)。细胞因子在IBD肠道炎症反应和黏膜免疫反应中起重要作用,目前已成为研究IBD发病机制的热点,本文就其在IBD中的作用作一综述。     

Induction of Murine Intestinal Inflammation by Adoptive Transfer of Effector CD4+CD45RBhigh T Cells into Immunodeficient Mice

There are many different animal models available for studying the pathogenesis of human inflammatory bowel diseases (IBD), each with its own advantages and disadvantages. We describe here an experimental colitis model that is initiated by adoptive transfer of syngeneic splenic CD4⁺CD45RB^high T cells into T and B cell deficient recipient mice. The CD4⁺CD45RB^high T cell population that largely consists of naïve effector cells is capable of inducing chronic intestinal inflammation, closely resembling key aspects of human IBD. This method can be manipulated to study aspects of disease onset and progression. Additionally it can be used to study the function of innate, adaptive, and regulatory immune cell populations, and the role of environmental exposures, i.e., the microbiota, in intestinal inflammation. In this article we illustrate the methodology for inducing colitis with a step-by-step protocol. This includes a video demonstration of key technical aspects required to successfully develop this murine model of experimental colitis for research purposes.     

Lessons from genetically engineered animal models. XII. IL-10-deficient (IL-10(-/-) mice and intestinal inflammation

Interleukin (IL)-10(-/-) mice spontaneously develop intestinal inflammation characterized by discontinuous transmural lesions affecting the small and large intestine and by dysregulated production of proinflammatory cytokines. The uncontrolled generation of IFN-gamma-producing CD4(+) T cells (Th1 type) has been shown to play a causal role in the development of enterocolitis affecting these mutants. This article discusses studies of IL-10(-/-) mice that have investigated the role of enteric organisms in triggering intestinal disease, the mediators responsible for initiating and maintaining intestinal disease, the role IL-10 plays in the generation and/or function of regulatory cells, and the results of IL-10 therapy in experimental animal models of inflammatory bowel disease (IBD) and human patients with IBD.     

Cutting edge: transgenic expression of human MUC1 in IL-10-/- mice accelerates inflammatory bowel disease and progression to colon cancer

Epithelial cell MUC1 is aberrantly expressed on human epithelial adenocarcinomas where it functions as a regulator of immune responses and an oncogene. Normally expressed at low levels in healthy colonic epithelium, MUC1 was reported to be overexpressed in human inflammatory bowel disease (IBD) and thus may be expected to play an important role in regulating chronic inflammation and its progression to colitis-associated colon cancer. Studies in the immunobiology and pathology of IBD and colitis-associated colon cancer have been done in various mouse models but none could properly address the role of MUC1 due to low homology between the mouse and the human molecule. We report that IL-10(-/-) mice, a widely accepted mouse model of IBD, crossed to human MUC1-transgenic mice, develop MUC1(+) IBD characterized by an earlier age of onset, higher inflammation scores, and a much higher incidence and number of colon cancers compared with IL-10(-/-) mice.     

Lessons from genetically engineered animal models XI. Novel mouse models to study pathogenic mechanisms of Crohn's disease

Crohn's Disease (CD) affects more than 500,000 individuals in the United States and represents the second most common chronic inflammatory disorder after rheumatoid arthritis. Although major advances have been made in defining the basic mechanisms underlying chronic intestinal inflammation, the precise etiopathogenesis of CD remains unknown. We have recently characterized two novel mouse models of enteritis that express a CD-like phenotype, namely the TNF DeltaARE model of tumor necrosis factor (TNF) overexpression and the SAMP1/Yit model of spontaneous ileitis. The unique feature of these models is that they closely resemble CD for location and histopathology. These genetically manipulated new models of intestinal inflammation offer a powerful tool to investigate potential causes of human disease and may allow the development of novel disease-modifying therapeutic modalities for the treatment of CD.     

Sparse Modeling Reveals miRNA Signatures for Diagnostics of Inflammatory Bowel Disease

The diagnosis of inflammatory bowel disease (IBD) still remains a clinical challenge and the most accurate diagnostic procedure is a combination of clinical tests including invasive endoscopy. In this study we evaluated whether systematic miRNA expression profiling, in conjunction with machine learning techniques, is suitable as a non-invasive test for the major IBD phenotypes (Crohn''s disease (CD) and ulcerative colitis (UC)). Based on microarray technology, expression levels of 863 miRNAs were determined for whole blood samples from 40 CD and 36 UC patients and compared to data from 38 healthy controls (HC). To further discriminate between disease-specific and general inflammation we included miRNA expression data from other inflammatory diseases (inflammation controls (IC): 24 chronic obstructive pulmonary disease (COPD), 23 multiple sclerosis, 38 pancreatitis and 45 sarcoidosis cases) as well as 70 healthy controls from previous studies. Classification problems considering 2, 3 or 4 groups were solved using different types of penalized support vector machines (SVMs). The resulting models were assessed regarding sparsity and performance and a subset was selected for further investigation. Measured by the area under the ROC curve (AUC) the corresponding median holdout-validated accuracy was estimated as ranging from 0.75 to 1.00 (including IC) and 0.89 to 0.98 (excluding IC), respectively. In combination, the corresponding models provide tools for the distinction of CD and UC as well as CD, UC and HC with expected classification error rates of 3.1 and 3.3%, respectively. These results were obtained by incorporating not more than 16 distinct miRNAs. Validated target genes of these miRNAs have been previously described as being related to IBD. For others we observed significant enrichment for IBD susceptibility loci identified in earlier GWAS. These results suggest that the proposed miRNA signature is of relevance for the etiology of IBD. Its diagnostic value, however, should be further evaluated in large, independent, clinically well characterized cohorts.     

The role of heme oxygenase and carbon monoxide in inflammatory bowel disease

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease, is a chronic and recurrent inflammatory disorder of the intestinal tract. Since the precise pathogenesis of IBD remains unclear, it is important to investigate the pathogenesis of IBD and to evaluate new anti-inflammatory strategies. Recent evidence suggests that heme oxygenase-1 (HO-1) plays a critical protective role during the development of intestinal inflammation. In fact, it has been demonstrated that the activation of HO-1 may act as an endogenous defensive mechanism to reduce inflammation and tissue injury in various animal intestinal injury models induced by ischemia-reperfusion, indomethacin, lipopolysaccharide-associated sepsis, trinitrobenzene sulfonic acid or dextran sulfate sodium. In addition, carbon monoxide (CO) derived from HO-1 has been shown to be involved in the regulation of intestinal inflammation. Furthermore, administration of a low concentration of exogenous CO has a protective effect against intestinal inflammation. These data suggest that HO-1 and CO may be novel therapeutic molecules for patients with gastrointestinal inflammatory diseases. In this review, we present what is currently known regarding the role of HO-1 and CO in intestinal inflammation.     

Intermittent administration of a fasting-mimicking diet reduces intestinal inflammation and promotes repair to ameliorate inflammatory bowel disease in mice

Recent studies have revealed that calorie restriction is able to modulate immune system and aid in intervention of immune disorders. Inflammatory bowel disease (IBD) is an immune disease in the intestine caused by interplay between genetic susceptibility and environmental factors such as diets. Here we analyzed the therapeutic effect of intermittent calorie restriction with a fasting-mimicking diet (FMD) on dextran sodium sulfate (DSS)-induced chronic IBD model in mice. Two cycles of FMD was administered after IBD symptoms occurred in the mice. FMD administration significantly reduced the score of disease activity index. FMD reversed DSS-mediated shortening of colon length, infiltration of lymphocytes in the crypt of colon, and accumulation of CD4⁺ cells in the colon and small intestine. The expression of an inflammation marker NLRP3 was also reduced by FMD administration. The percentage of CD4⁺ T cells in both peripheral blood and spleen was also reduced by FMD. In addition, FMD application reversed DSS-mediated reduction in intestinal stem cell marker Lgr5, while the cell proliferation markers Ki67 and PCNA were increased by FMD. Taken together, these results indicate that in the mouse model of IBD, application of the FMD can effectively ameliorate the symptoms and pathogenesis of IBD through reducing the inflammation of intestine and promoting the regeneration and repair of the damaged intestinal epithelium.     

Intestinal epithelial cell signalling and chronic inflammation: From the proteome to specific molecular mechanisms

Advancing knowledge regarding the cellular mechanisms of intestinal inflammation has led to a better understanding of the disease pathology in patients with inflammatory bowel disease (IBD) including Crohn's disease and ulcerative colitis. It has become clear from numerous studies that enteric bacteria are a critical component in the development and prevention/treatment of chronic intestinal inflammation. An emerging new paradigm suggests that changes in the homeostasis of bacteria- and host-derived signal transduction at the intestinal epithelial cell (IEC) level may lead to a break in barrier function and the development of adaptive immune disturbances. The functional loss of anti-inflammatory host-derived signals in the gut including the immunosuppressive cytokines Interleukin 10 (IL-10) and transforming growth factor (TGF)-beta are of high relevance to the pathogenesis of IBD. The development of analytical tools including two-dimensional (2D) high-resolution protein separation techniques and peptide mass fingerprinting via high-sensitivity mass-spectrometers (MS) allows the quantitative assessment of protein expression changes in disease-relevant cell types. By using these advanced methods, the characterization of the epithelial cell proteome from murine models of experimental colitis and human IBD patients identified novel disease-related mechanisms with respect to the regulation of the glucose-regulated endoplasmic reticulum stress response protein 78 (grp-78). In conclusion, the identification and functional analysis of differentially expressed proteins in purified intestinal target cell types will help to add important insights to the understanding of the molecular pathogenesis of these immune-mediated chronic intestinal disorders.     

A novel murine model of inflammatory bowel disease and inflammation-associated colon cancer with ulcerative colitis-like features

Mutations that increase susceptibility to inflammatory bowel disease (IBD) have been identified in a number of genes in both humans and mice, but the factors that govern how these mutations contribute to IBD pathogenesis and result in phenotypic presentation as ulcerative colitis (UC) or Crohn disease (CD) are not well understood. In this study, mice deficient in both TNF and IL-10 (T/I mice) were found to spontaneously develop severe colitis soon after weaning, without the need for exogenous triggers. Colitis in T/I mice had clinical and histologic features similar to human UC, including a markedly increased risk of developing inflammation-associated colon cancer. Importantly, development of spontaneous colitis in these mice was prevented by antibiotic treatment. Consistent with the known role of Th17-driven inflammation in response to bacteria, T/I mice had elevated serumTh17-type cytokines when they developed spontaneous colitis and after systemic bacterial challenge via NSAID-induced degradation of the mucosal barrier. Although TNF production has been widely considered to be be pathogenic in IBD, these data indicate that the ability to produce normal levels of TNF actually protects against the spontaneous development of colitis in response to intestinal colonization by bacteria. The T/I mouse model will be useful for developing new rationally-based therapies to prevent and/or treat IBD and inflammation-associated colon cancer and may further provide important insights into the pathogenesis of UC in humans.     

IL-23 in inflammatory bowel diseases and colon cancer

Studies in recent years have identified a pivotal role of the cytokine IL-23 in the pathogenesis of inflammatory bowel diseases (IBD: Crohn´s disease, ulcerative colitis) and colitis-associated colon cancer. Genetic studies revealed that subgroups of IBD patients have single nucleotide polymorphisms in the IL-23R gene suggesting that IL-23R signaling affects disease susceptibility. Furthermore, increased production of IL-23 by macrophages, dendritic cells or granulocytes has been observed in various mouse models of colitis, colitis-associated cancer and IBD patients. Moreover, in several murine models of colitis, suppression of IL-12/IL-23 p40, IL-23 p19 or IL-23R function led to marked suppression of gut inflammation. This finding was associated with reduced activation of IL-23 target cells such as T helper 17 cells, innate lymphoid cells type 3, granulocytes and natural killer cells as well as with impaired production of proinflammatory cytokines. Based on these findings, targeting of IL-23 emerges as important concept for suppression of gut inflammation and inflammation-associated cancer growth. Consistently, neutralizing antibodies against IL-12/IL-23 p40 and IL-23 p19 have been successfully used in clinical trials for therapy of Crohn´s disease and pilot studies in ulcerative colitis are ongoing. These findings underline the crucial regulatory role of IL-23 in chronic intestinal inflammation and colitis-associated cancer and indicate that therapeutic strategies aiming at IL-23 blockade may be of key relevance for future therapy of IBD patients.     

Gut-associated lymphoid tissue, T cell trafficking, and chronic intestinal inflammation

The etiologies of the inflammatory bowel diseases (IBD; Crohn's disease, ulcerative colitis) have not been fully elucidated. However, there is very good evidence implicating T cell and T cell trafficking to the gut and its associated lymphoid tissue as important components in disease pathogenesis. The objective of this review is to provide an overview of the mechanisms involved in naive and effector T cell trafficking to the gut-associated lymphoid tissue (GALT; Peyer's patches, isolated lymphoid follicles), mesenteric lymph nodes and intestine in response to commensal enteric antigens under physiological conditions as well as during the induction of chronic gut inflammation. In addition, recent data suggests that the GALT may not be required for enteric antigen-driven intestinal inflammation in certain mouse models of IBD. These new data suggest a possible paradigm shift in our understanding of how and where naive T cells become activated to yield disease-producing effector cells.     

Worms,flies and four-legged friends: the applicability of biological models to the understanding of intestinal inflammatory diseases

Diseases of intestinal inflammation, including Crohn’s disease, ulcerative colitis and necrotizing enterocolitis, cause substantial acute and chronic disability in a large proportion of the population. Crohn’s disease and ulcerative colitis, which are collectively referred to as inflammatory bowel disease (IBD), lead to recurrent episodes of intestinal dysfunction and systemic illness, whereas necrotizing enterocolitis is characterized by the development of dramatic and all too often fatal intestinal necrosis in infants. To determine the molecular underpinnings of these disorders, investigators have explored a variety of animal models that vary widely in their complexity. These experimental systems include the invertebrate nematode Caenorhabditis elegans, the more complex invertebrate Drosophila melanogaster, and vertebrate systems including mice, rats and other mammals. This review explores the experimental models that are used to mimic and evaluate the pathogenic mechanisms leading to these diseases of intestinal inflammation. We then highlight, as an example, how the use of different experimental models that focus on the role of Toll-like receptor 4 (TLR4) signaling in the gut has revealed important distinctions between the pathogenesis of IBD and necrotizing enterocolitis. Specifically, TLR4-mediated signaling plays a protective role in the development of Crohn’s disease and ulcerative colitis, whereas this signaling pathway plays a causative role in the development of necrotizing enterocolitis in the newborn small intestine by adversely affecting intestinal injury and repair mechanisms.     

益生菌在儿童炎症性肠病中的应用

炎症性肠病(inflammatory bowel disease,IBD)是一种原因不明的慢性非特异性肠道炎性疾病,主要包括溃疡性结肠炎(ulcerative colitis,UC)、克罗恩病(Crohn′s disease,CD)和未定型的炎症性肠病(IBD-unclassified,IBDU)。随着对肠道微生物与IBD关系认识的不断加深,许多研究发现肠道菌群的生态失调在IBD的发病中起着重要作用。益生菌在儿童IBD治疗中具有良好前景,但仍缺乏有效的证据来确证益生菌疗效,并指导临床对益生菌的种类和剂量等进行选择。现有研究表明,益生菌对儿童IBD的治疗具有特异性,在诱导和维持UC缓解效果明显,但在诱导CD缓解、维持CD缓解和预防术后并发症及复发方面效果并不理想。     

Prevention of experimental colitis in SCID mice reconstituted with CD45RBhigh CD4+ T cells by blocking the CD40-CD154 interactions

Increased expression of CD40 and CD40 ligand (CD40L or CD154) has been found in inflamed mucosa of human inflammatory bowel disease (IBD), and interactions between these molecules seem to be involved in local cytokine production by macrophages. However, the precise role of CD40 signaling in the pathogenesis of IBD is still poorly understood. The aim of the present study was to investigate the in vivo relevance of CD40 signaling in experimental colitis in SCID mice reconstituted with syngeneic CD45RBhighCD4+ T cells. The results demonstrated that CD40+ and CD40L+ cells as well as their mRNA levels were significantly increased in inflamed mucosa. Administration of anti-CD40L neutralizing mAb over an 8-wk period starting immediately after CD45RBhighCD4+ T cell reconstitution completely prevented symptoms of wasting disease. Intestinal mucosal inflammation was effectively prevented, as revealed by abrogated leukocyte infiltration and decreased CD54 expression and strongly diminished mRNA levels of the proinflammatory cytokines IFN-gamma, TNF, and IL-12. When colitic SCID mice were treated with anti-CD40L starting at 5 wk after T cell transfer up to 8 wk, this delayed treatment still led to significant clinical and histological improvement and down-regulated proinflammatory cytokine secretion. These data suggest that the CD40-CD40L interactions are essential for the Th1 inflammatory responses in the bowel in this experimental model of colitis. Blockade of CD40 signaling may be beneficial to human IBD.     

CD98 Positive Eosinophils Contribute to T Helper 1 Pattern Inflammation

Background and Aims

The pathogenesis of inflammatory bowel disease (IBD) has not been fully understood yet. Eosinophils (Eo) are one type of the major proinflammatory cells of the chronic inflammation in the intestine. CD98 is involved in the pathogenesis of a number of inflammations. This study aims to elucidate the role of CD98⁺ Eos in the initiation of intestinal inflammation.

Methods

The colon biopsies were collected from 60 patients with IBD. The expression of CD98 in the biopsies was examined by immunohistochemistry. The serum levels of the flagellin (FGN) antibody and Eo-derived mediators in the culture supernatants were assessed by enzyme-linked immunosorbent assay. The role of FGN on Eo activation was examined in a cell culture model. The role of FGN in the induction of colitis was observed in a mouse model.

Results

Compared to normal controls, the frequency of CD98⁺ Eos was markedly increased in the IBD colon mucosa. FGN were detected in the colon biopsies and in the sera of IBD patients. Exposure to FGN induced the expression of galectin 3 (the ligand of CD98) in dendritic cells. The exposure to galectin 3 activated the CD98⁺ Eos. After treatment with FGN intrarectally, mice with eosinophilia showed severe inflammation in the colon.

Conclusions

The interaction of galectin 3 and CD98 can induce Eos to release chemical mediators that contributes to the initiation of the intestinal inflammation.     

VEGF-A stimulation of leukocyte adhesion to colonic microvascular endothelium: implications for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder characterized by increased leukocyte recruitment and subsequent tissue damage. An increase in the density of the microvasculature of the colon during IBD has been suggested, leading to the concept that angiogenesis may play a pathological role in IBD. Increased tissue and serum levels of the angiogenic cytokine VEGF-A have been reported in cases of active IBD. In this study, we examined the hypothesis that VEGF-A exerts a proinflammatory effect on colon microvascular endothelium that contributes to colonic inflammation. Leukocyte adhesion to VEGF-A-stimulated colon microvascular endothelial cells was examined using a parallel-plate hydrodynamic flow chamber. ICAM-1 adhesion molecule expression on colonic microvascular endothelium also was determined in response to VEGF-A stimulation, along with characterization of leukocyte adhesion molecule expression. High-dose VEGF-A (50 ng/ml) stimulation increased neutrophil and T cell adhesion to and decreased rolling velocities on activated endothelium, whereas low-dose VEGF-A (10 ng/ml) was without effect. Colonic endothelium constitutively expressed ICAM-1, which was significantly increased by treatment with 50 ng/ml VEGF-A or 10 ng/ml TNF-alpha but not 10 ng/ml VEGF-A. T cells expressed CD18 and CD11a with no expression of CD11b, whereas neutrophils expressed CD18, CD11a, and CD11b. Finally, VEGF-A-dependent leukocyte adhesion was found to occur in a CD18-dependent manner. These results demonstrate that VEGF-A levels found in IBD exert a proinflammatory effect similar to other inflammatory agents and suggest that this cytokine may serve as an intermediary between angiogenic stimulation and cell-mediated immune responses.     

Increased expression and activation of IL-12-induced Stat4 signaling in the mucosa of ulcerative colitis patients

Inflammatory bowel diseases (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), are chronic inflammatory diseases with unsolved pathogenesis. Imbalanced Th1/Th2 may play a role in the sustained inflammation of IBD. In China, CD is rare but the incidence of UC has been rising steadily in the last two decades. We investigated the expression of IL-12 (p40) and IFN-γ, and the activational state of Stat4 signaling in mucosal tissues at the site of disease from 30 active UC patients in comparison with 30 healthy controls. RT-PCR analyses revealed increased mRNA expression of IL-12 (p40) but not IFN-γ in UC patients. Western blot analyses discovered, for the first time, increased levels of constitutive Stat4 in the cytoplasm and phosphorylated Stat4 in the nucleus of mucosal cells from UC patients. We conclude that a heightened, perhaps persistent, activational state of IL-12/Stat4, and/or IL-23/Stat4 signaling may be present in active Chinese UC patients, and possibly involved in chronic inflammation in UC.     

The role of the Hippo pathway in the pathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic and recurrent inflammatory disorder that primarily comprises Crohn’s disease (CD) and ulcerative colitis (UC). Owing to its increasing prevalence in Eastern countries and the intractable challenges faced during IBD treatment, extensive research on IBD has been carried out over the last few years. Although the precise aetiology of IBD is undefined, the currently accepted hypothesis for IBD pathogenesis considers it to be a combination of environment, genetic predisposition, gut microbiota, and abnormal immunity. A recently emerged signalling pathway, the Hippo pathway, acts as a key regulator of cell growth, tissue homoeostasis, organ size, and has been implicated in several human cancers. In the past few years, studies have revealed the importance of the Hippo pathway in gastrointestinal tract physiology and gastrointestinal diseases, such as colorectal cancer and IBD. However, the role of the Hippo pathway and its exact impact in IBD remains to be elucidated. This review summarises the latest scientific literature on the involvement of this pathway in IBD from the following perspectives that account for the IBD pathogenesis: intestinal epithelial cell regeneration, immune regulation, gut microbiota, and angiogenesis. A comprehensive understanding of the specific role of the Hippo pathway in IBD will provide novel insights into future research directions and clinical implications of the Hippo pathway.Subject terms: Post-translational modifications, Chronic inflammation