Th17/Treg失衡与炎症性肠病的关系

炎症性肠病(inflammatory bowel disease.IBD)的病因和发病机制尚未完全明确,肠道黏膜免疫系统异常反应所导致的炎症过程在发病中起重要作用.辅助性T细胞17(T helper 17 cells,Th17)可介导慢性炎症和自身免疫性疾病的发生,调节性T细胞(regulatory T cell,Treg)有抑制自身免疫的功能,二者存在相互转化的关系.有研究表明Th17/Treg转化平衡是维持肠道免疫稳态的重要因素,这可能是导致人类IBD的原因之一.最近研究表明TGF-β,IL-6和维甲酸(retinoic acid,RA)可能是调控二者平衡关系的重要因素.肠道菌群(intestinal flora)与IBD的发生发展关系密切,益生菌(probiotics)对IBD的治疗作用成为研究的热点.深化对Th17/Treg转化调控关系的研究是当前重要的研究课题.     

Dysregulation of mucosal immune response in pathogenesis of inflammatory bowel disease

Inflammatory bowel disease(IBD)includes Crohn’s disease and ulcerative colitis.The exact etiology and pathology of IBD remain unknown.Available evidence suggests that an abnormal immune response against the microorganisms in the intestine is responsible for the disease in genetically susceptible individuals.Dysregulation of immune response in the intestine plays a critical role in the pathogenesis of IBD,involving a wide range of molecules including cytokines.On the other hand,besides T helper(Th)1 and Th2 cell immune responses,other subsets of T cells,namely Th17 and regulatory T cells,are likely associated with disease progression.Studying the interactions between various constituents of the innate and adaptive immune systems will certainly open new horizons of the knowledge about the immunologic mechanisms in IBD.     

Differential expression of CCR5 and CRTH2 on infiltrated cells in colonic mucosa of patients with ulcerative colitis

BACKGROUND AND AIM: The pathogenesis of ulcerative colitis (UC) is unclear, but abnormal infiltration of T lymphocytes in the colonic mucosa has been implicated in the mucosal tissue damage. The abnormal cytokine production because of a T helper (h)1/Th2 imbalance may play an important role in continuing inflammation in the colonic mucosa. In the present study, the expression of chemokine receptor 5 (CCR5) as a Th1 marker and a chemoattractant receptor-homologs molecule expressed on Th2 cells (CRTH2) were investigated in order to analyze impaired Th1/Th2 responses in the colonic mucosa of UC patients. METHODS: Tissue samples were obtained by colonic biopsies from patients with UC or colonic polyps, with informed consent. Immunohistochemical analysis was performed on periodate, lysine-paraformaldehyde-fixed serial cryostat sections using the labeled streptavidin biotin method. Monoclonal antibodies against CD4, CCR5 or CRTH2 were used as primary antibodies. The number of cells expressing CD4, CCR5 or CRTH2 per unit area was calculated by using an image analyzer. RESULTS: In the patients with UC, the numbers of CD4- and CCR5-positive cells were significantly increased in inflamed mucosa, and appeared to be correlated with the disease activity. The infiltration of CRTH2-positive cells was predominantly observed in the mildly inflamed or the margin of inflamed mucosa of UC patients. CONCLUSION: There is a possibility that Th1 responses significantly occur in colonic mucosa with severe inflammation, while Th2 responses mainly occur with mild inflammation in UC patients. The Th1/Th2 imbalance in colonic mucosa may be related to the disease progression of UC.     

Old and New Lymphocyte Players in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), encompassing Crohn’s disease and ulcerative colitis, is a chronic intestinal inflammatory disorder characterized by diffuse accumulation of lymphocytes in the gut mucosa as a consequence of over-expression of endothelial adhesion molecules. The infiltrating lymphocytes have been identified as subsets of T cells, including T helper (Th)1 cells, Th17 cells, and regulatory T cells. The function of these lymphocyte subpopulations in the development of IBD is well-known, since they produce a number of pro-inflammatory cytokines, such as interferon-γ and interleukin-17A, which in turn activate mucosal proteases, thus leading to the development of intestinal lesions, i.e., ulcers, fistulas, abscesses, and strictures. However, the immune mechanisms underlying IBD are not yet fully understood, and knowledge about the function of newly discovered lymphocytes, including Th9 cells, innate lymphoid cells, mucosal-associated invariant T cells, and natural killer T cells, might add new pieces to the complex puzzle of IBD pathogenesis. This review summarizes the recent advances in the understanding of the role of mucosal lymphocytes in chronic intestinal inflammation and deals with the therapeutic potential of lymphocyte-targeting drugs in IBD patients.     

The Interleukin-23 / Interleukin-17 axis in intestinal inflammation

Although the precise aetiology of inflammatory bowel disease (IBD) remains unclear, recent discoveries have led to an improved understanding of disease pathogenesis. Whilst these findings have underscored the central role of innate and adaptive immune responses in intestinal inflammation, they have also precipitated a paradigm shift in the key cytokine pathways that drive disease. The prevailing dogma that IBD was mediated by interleukin (IL)-12-driven T-helper (Th)1 CD4 T cell responses towards the bacterial flora has been largely dispelled by findings that the closely related cytokine IL-23 appears to be the key mediator of intestinal inflammation. IL-23 is associated with a novel subset of IL-17-secreting CD4 T cells termed Th17 cells and rodent studies have implicated the IL-23/IL-17 axis in autoimmune inflammation. Genome-wide association studies in IBD patients have confirmed the predominant role of the IL-23 pathway, indicating that this could represent an important future therapeutic target.     

Plasmapheresis Affects T Helper Type‐1/T Helper Type‐2 Balance of Circulating Peripheral Lymphocytes

Abstract: Plasmapheresis not only removes humoral factors, but may also modulate cellular immunity. We investigated whether plasmapheresis influenced T helper type‐1/T helper type‐2 (Th1/Th2) cytokine‐producing‐cell balance in 3 patients with neuroimmunological disease. The production of interferon‐γ (IFN‐γ), interleukin‐2 (IL‐2), and IL‐4 in the culture supernatant of peripheral blood mononuclear cells stimulated by anti‐CD3 and anti‐CD28 was assayed. In 2 of 3 patients, plasmapheresis (immunoadsorption or plasma exchange) reduced Th1/Th2 cytokine ratio. The results may suggest that plasmapheresis induces a shift of Th1/Th2 balance in peripheral blood.     

Significant elevation of serum interleukin-18 levels in patients with acute pancreatitis

Background We have reported that peripheral lymphocyte reduction due to apoptosis is linked to the development of subsequent infectious complications in patients with severe acute pancreatitis and that Th1 (helper T cell type 1)/Th2 (helper T cell type 2) balance tends to cause Th1 suppression in experimental severe acute pancreatitis. It has been reported that interleukin (IL)-18 is a cytokine produced from Kupffer cells and activated macrophages, and that IL-18 acts on Th1 cells and in combination with IL-12 strongly induces production of interferon-γ. However, the role of IL-18 in acute pancreatitis has not yet been fully understood. Methods Serum IL-18 concentrations were determined by an enzyme-linked immunosorbent assay in 43 patients with acute pancreatitis at the time of admission. The relationships with etiology, pancreatic necrosis, severity, blood biochemical parameters on admission, infection, and organ dysfunction during the clinical course and prognosis were analyzed. Results Serum IL-18 levels in patients with acute pancreatitis (656 ± 11pg/ml) were significantly higher than those in healthy volunteers (126 ± pg/ml). Serum IL-18 levels were significantly positively correlated with the Ranson score and Japanese severity score. Among the blood biochemical parameters on admission, base excess and total protein were significantly negatively correlated with serum IL-18 levels. Moreover, the CD4/CD8 rate of lymphocytes, serum IL-6 levels, and serum IL-8 levels were significantly positively correlated with serum IL-18 levels. On day 7 after admission, the CD4/CD8 rate of lymphocytes and the rate of CD4-positive lymphocytes were significantly positively correlated with serum IL-18 levels. Furthermore, serum IL-18 levels in patients with hepatic dysfunction (980 ± 25pg/ml) were significantly higher than those without hepatic dysfunction (464 ± 8pg/ml). Serum IL-18 levels were not related to infection or prognosis. Elevation of serum IL-18 levels continued during 4 weeks after admission. Conclusions These results suggest that serum IL-18 levels are significantly elevated and are correlated with severity in patients with acute pancreatitis and that IL-18 may be closely related to helper T cell response and hepatic dysfunction in this disease.     

The expression of chemokine receptor CXCR3: relevance to disease activity of rheumatoid arthritis

 CXC chemokine receptor 3 (CXCR3) is selectively expressed on T helper 1 (Th1) type T cells and has been shown to be responsible for Th1-dominant immune responses. In this study, we analyzed the expression of CXCR3 on peripheral blood T lymphocytes of patients with rheumatoid arthritis (RA) by FACS analysis using antihuman CXCR3 monoclonal antibody and determined the clinical relevance in this disease. Significantly higher expression of CXCR3 was found on peripheral blood CD4+ T lymphocytes of RA patients than healthy controls. The CXCR3 expression in RA patients with a high erythrocyte sedimentation rate was significantly higher than in those with a low erythrocyte sedimentation rate. Moreover, we found that the CXCR3 expression in RA patients with long-term disease duration was significantly higher than in those with short-term disease. On the other hand, CC chemokine receptor 4 (CCR4), which was shown to be selectively expressed on Th2-type T cells, was expressed at low levels in RA patients as well as in healthy controls. The serum level of interleukin (IL)-18 in RA patients was higher than that in healthy controls, although there was no statistically significant difference. This study suggests that the Th1 immune response is predominant in RA and that CXCR3 may have relevance in regard to the disease course in RA patients. Received: January 28, 2002 / Accepted: August 14, 2002     

调节性T细胞在炎症性肠病中的研究进展

炎症性肠病(IBD)是一种非特异性肠道炎症性疾病,其发病与自身免疫功能紊乱有关.Th1/Th2失衡是导致IBD的重要因素之一.然而,Th1/Th2理论并不能充分阐明IBD的发病机制.近几年来,越来越多的研究显示,调节性T细胞在炎症性肠病的发生发展中起重要的作用.本文就近年来调节性T细胞在炎症性肠病中作用的研究进展作一综述.     

Cytokine detection by ELISPOT: relevance for immunological studies in type 1 diabetes

Diabetes mellitus type 1 is a chronic disease in which the insulin-secreting ss-cells are selectively destroyed by an immune-mediated process. Autoantibodies directed against several islet antigens are useful parameters to estimate the risk to develop diabetes, but cell-mediated immunity involving T lymphocytes plays a major part in causing the specific destruction of ss-cells. T cells are characterized by their antigen-specificity, phenotype and cytokine-secreting profile. T cells that secrete cytokines of the T helper 1 (Th1) type have been shown to transfer diabetes in animal studies, in contrast to T helper 2 (Th2) cytokine-secreting T cells that are thought to be rather nondestructive. In the absence of phenotypic markers for Th1 and Th2 cells, several different approaches have been taken to examine T cell responses in detail. Methods involve T-cell proliferation assays, Enzyme-Linked-Immuno-Sorbent-Assay (ELISA) analysis of secreted cytokines and phenotype analysis applying flow cytometry. A more recent development is ELISPOT analysis, which enables the investigator to determine the qualitative and quantitative antigen-specific immune response on a single-cell level with regard to cytokine secretion. This article aims to give an introduction to the advantages and limitations inherent in the different techniques and their potential relevance for immunological studies in diabetes mellitus type 1.     

Impairment of ghrelin synthesis in Helicobacter pyloricolonized stomach:New clues for the pathogenesis of H.pylori-related gastric inflammation

Ghrelin,the ligand of growth hormone secretagogue receptor 1a,takes part in several functions of the digestive system,including regulation of appetite,energy homeostasis,gastric acid secretion and motility.Ghrelin has also immunoregulatory properties and is supposed to inhibit some inflammatory pathways that can mediate gastric damage.Interestingly,ghrelin synthesis is reduced in the gastric mucosa of patients with Helicobacter pylori(H.pylori)infection,a worldwide condition inducing a T helper(Th)1/Th17 cell responsedriven gastritis,which may evolve towards gastric atrophy and cancer.In this article,we review the available data on the expression of ghrelin in H.pylori infection and discuss how the defective ghrelin synthesis may contribute to sustain the ongoing inflammatory response in this disease.     

TCRzetadim lymphocytes define populations of circulating effector cells that migrate to inflamed tissues

The T-cell receptor zeta (TCRzeta) chain is a master sensor and regulator of lymphocyte responses. Loss of TCRzeta expression has been documented in infectious, inflammatory, and malignant diseases, suggesting that it may serve to limit T-cell reactivity and effector responses at sites of tissue damage. These observations prompted us to explore the relationship between TCRzeta expression and effector function in T cells. We report here that TCRzeta(dim) lymphocytes are enriched for antigen-experienced cells refractory to TCR-induced proliferation. Compared to their TCRzeta(bright) counterparts, TCRzeta(dim) cells share characteristics of differentiated effector T cells but use accessory pathways for transducing signals for inflammatory cytokine gene expression and cell contact-dependent pathways to activate monocytes. TCRzeta(dim) T cells accumulate in inflamed tissues in vivo and have intrinsic migratory activity in vitro. Whilst blocking leukocyte trafficking with anti-TNF therapy in vivo is associated with the accumulation of TCRzeta(dim) T cells in peripheral blood, this T-cell subset retains the capacity to migrate in vitro. Taken together, the functional properties of TCRzeta(dim) T cells make them promising cellular targets for the treatment of chronic inflammatory disease.     

Role of interferon alpha in promoting T helper cell type 1 responses in the small intestine in coeliac disease

Coeliac disease (CD) is caused by a CD4 T helper cell type 1 (Th1) response in the small intestinal mucosa to dietary gluten. As the major Th1 inducing cytokine, interleukin 12, is undetectable in CD gut mucosa, the mechanism by which Th1 effector cells are generated remains unknown. Interferon (IFN) alpha, a cytokine capable of promoting IFN-gamma synthesis, has been implicated in the development of Th1 mediated immune diseases. Here we report a case of CD-like enteropathy in a patient receiving IFN-alpha for chronic myeloid leukaemia. Morphological assessment of duodenal biopsies taken from the patient showed total villous atrophy, crypt cell hyperplasia, and a high number of CD3+ intraepithelial lymphocytes. Both antigliadin antibodies and antiendomysial antibodies were positive. RNA analysis revealed pronounced expression of IFN-gamma. Withdrawal of gluten from the diet resulted in a patchy improvement in intestinal morphology, normalisation of laboratory parameters, and resolution of clinical symptoms. By western blot analysis, IFN-alpha protein was seen in the duodenal mucosa from untreated CD patients but not in controls. This was associated with marked expression of IFN-gamma protein in CD mucosa. Collectively, these results suggest a role for IFN-alpha in promoting Th1 responses to gluten.     

Signaling for inflammation and repair in inflammatory bowel disease

In patients with inflammatory bowel diseases (IBD) the immune system leads to the polarization of intestinal immune cells towards a T helper one (Th1) pro-inflammatory response. The immunologic factors intervene in intestinal homeostasis and initiate the development of intestinal mucosal inflammation. Cytokines, which are important regulators of inflammation and repair as wells as leukocyte trafficking have become apparent as key immune molecules in the pathogenesis of IBD. In this review, recent advances in our understanding of the cytokine involvement in inflammation and repair in patients with ulcerative colitis (UC) and Crohn's disease (CD) are discussed. Knowledge of objective evidence of inflammatory activity may allow targeted treatment at an earlier stage to avoid the relapse, as well as assessment of new therapeutic strategies for maintenance of remission.     

γδT细胞在肺部铜绿假单胞菌感染的研究现状

γδT细胞是T细胞的一个亚群,存在Th1／Th2免疫模式,主要分布在皮肤、肠道、呼吸道及泌尿生殖道的黏膜和皮下组织,在感染性疾病的免疫应答中发挥着第一道防线的作用。铜绿假单胞菌是临床常见的致病菌,感染所诱发的免疫反应是以Th2型为主,伴有明显的第Ⅲ型超敏反应所导致的器官损害。铜绿假单胞菌感染时γδT细胞明显升高,γδT细胞可能通过分泌不同的细胞因子影响Th1／Th2平衡,进而影响铜绿假单胞菌感染性疾病的发生、发展。     

Th17细胞在炎症性肠病发病机制作用的研究进展

炎症性肠病的病因和发病机制尚未完全明确。最近的研究表明,Th17细胞及与其相关的细胞因子、Th细胞亚群所导致的炎症过程在炎症性肠病的发生发展中起重要作用。本文就Th17的分化调控机制及Th17与其相关的细胞因子、Th细胞亚群在炎症性肠病的发病机制中的作用作一概述。     

T‐helper 17 cell: A distinctive cell in liver diseases

T‐helper (Th)17 cells, a new population of effector CD4⁺ T cells, are characterized by the secretion of interleukin (IL)‐17. It has been demonstrated that Th17 cells are distinct from Th1 and Th2 cells; they play important roles in the pathogenesis of numerous inflammatory and autoimmune diseases; and are closely related to host defense, tumorigenesis and transplant rejection. Moreover, it has been found that these cells have a close and intricate connection with the regulatory T cells, which play an important role in maintaining self‐tolerance and down‐tuning immune responses. In the present review, we find that they are significantly elevated in various kinds of liver diseases including liver autoimmunity and inflammatory diseases, alcoholic liver disease and hepatocellular carcinoma.