Hyperexpression of inducible costimulator and its contribution on lamina propria T cells in inflammatory bowel disease

BACKGROUND & AIMS: To investigate the role of inducible costimulator (ICOS), a new member of the CD28 family involved in regulation of T-cell activation and chronic intestinal inflammation, we assessed its expression and functional role in patients with inflammatory bowel disease (IBD). METHODS: Expression of ICOS, CD28, and cytotoxic T-lymphocyte antigen (CTLA) 4 on intestinal lamina propria mononuclear cells (LPMC) from patients with ulcerative colitis (UC), Crohn's disease (CD), and normal controls was determined using flow cytometry and immunohistochemistry. Expressions of the ICOS ligand, B7h, on lamina propria B cells, macrophages, and epithelial cells (EC) in the intestinal mucosa were also determined using flow cytometry. The functional costimulatory effect of ICOS on LPMC was assessed by the proliferative response and cytokine production. RESULTS: CD4(+) LPMC expressing ICOS was significantly increased in the inflamed mucosa of IBD patients but not in inflammatory or normal controls. B7h was also significantly up-regulated on B cells, macrophages, and EC in inflamed mucosa of IBD patients. Proliferative responses of anti-CD3/ICOS costimulation were significantly higher compared with those of anti-CD3 monoclonal antibody (mAb) alone. Anti-CD3/ICOS-stimulated-LPMC from UC secreted significantly increased amounts of interleukin (IL)-5 among the 3 groups. In contrast, anti-CD3/ICOS-stimulated-LPMC from CD secreted significantly increased amounts of interferon (IFN)-gamma in the presence of IL-12. CONCLUSIONS: Highly expressed ICOS in activated CD4(+) LPMC of IBD patients contributes to the dysregulated immune responses in IBD. Because ICOS hyperexpression was limited to inflammatory sites in IBD patients, ICOS would be a feasible therapeutic target for the treatment of IBD.     

Interleukin-21 enhances T-helper cell type I signaling and interferon-gamma production in Crohn's disease

BACKGROUND & AIMS: T-helper (Th)1 cells play a central role in the pathogenesis of tissue damage in Crohn's disease (CD). Interleukin (IL)-12/STAT4 signaling promotes Th1 cell commitment in CD, but other cytokines are needed to maintain activated Th1 cells in the mucosa. In this study, we examined the expression and role of IL-21, a T-cell-derived cytokine of the IL-2 family; in tissues and cells isolated from patients with inflammatory bowel disease. METHODS: IL-21 was examined by Western blotting in whole mucosa and lamina propria mononuclear cells (LPMCs) from patients with CD, ulcerative colitis (UC), and controls. We also examined the effects of exogenous IL-12 on IL-21 production, as well as the effects of blocking IL-21 with an IL-21-receptor Ig fusion protein. Interferon (IFN)-gamma was measured in the culture supernatants by enzyme-linked immunosorbent assay, and phosphorylated STAT4 and T-bet were examined by Western blotting. RESULTS: IL-21 was detected in all samples, but its expression was higher at the site of disease in CD in comparison with UC and controls. Enhanced IL-21 was seen in both ileal and colonic CD and in fibrostenosing and nonfibrostenosing disease. IL-12 enhanced IL-21 in normal lamina propria lymphocytes through an IFN-gamma-independent mechanism, and blocking IL-12 in CD LPMCs decreased anti-CD3-stimulated IL-21 expression. Neutralization of IL-21 in CD LPMC cultures decreased phosphorylated STAT4 and T-bet expression, thereby inhibiting IFN-gamma production. CONCLUSIONS: Our data suggest that IL-21 contributes to the ongoing Th1 mucosal response in CD.     

Interleukin 18 is a potent proliferative factor for intestinal mucosal lymphocytes in Crohn's disease

BACKGROUND & AIMS: Crohn's disease (CD) is characterized by a marked accumulation of activated Th1 type CD4(+) T cells and macrophages in inflamed intestinal mucosa. Interleukin (IL)-18 is a recently described cytokine that mainly exists in activated macrophages and shares biological activities with IL-12 in driving the development of Th1 type CD4(+) T cells by inducing interferon gamma. To clarify the role of IL-18 in intestinal inflammation in CD, we assessed the functional role of IL-18 in regulating intestinal mucosal lymphocytes. METHODS: Serum IL-18 concentration was measured by enzyme-linked immunosorbent assay. Expression of IL-18 and IL-18 receptor in human intestinal mucosa was determined using immunohistochemistry and flow cytometry. The functional activity of IL-18 was assessed by the use of recombinant IL-18 to stimulate both the growth of intestinal mucosal lymphocytes and IL-2 receptor induction activity. RESULTS: The serum IL-18 concentration was significantly higher in patients with CD than normal controls. In the inflamed colonic mucosa of CD, many IL-18(+)CD68(+) macrophages had infiltrated the lamina propria. Intestinal mucosal lymphocytes from CD expressed functional IL-18 receptors. Recombinant IL-18 induced significant proliferative responses in freshly isolated mucosal lymphocytes from CD patients, but not from normal controls. IL-18 up-regulated IL-2 receptor expression in mucosal lymphocytes from patients with CD, but not from normal controls. CONCLUSIONS: These findings suggest that infiltrated macrophages in the inflamed intestinal mucosa in CD produce IL-18, and that macrophage-derived IL-18 may serve as a potent regulatory factor for intestinal mucosal lymphocytes, thereby contributing to chronic intestinal inflammation in CD.     

Evidence for a differential expression of fibronectin splice forms ED-A and ED-B in Crohn’s disease (CD) mucosa

BACKGROUND AND AIMS: Fibronectin (FN) is an essential factor for the induction of migration of primary colonic lamina propria fibroblasts (CLPF). The FN isoform ED-A is an important inducer of migration. Recently, we have shown that CLPF isolated from inflamed Crohn's disease (CD) mucosa migrated significantly less than control CLPF. We, therefore, investigated changes in FN or integrin expression that could be relevant for CLPF migration. MATERIALS AND METHODS: mRNA of control-CLPF and CLPF isolated from fibrotic mucosa of CD patients was subtractively hybridized. Expression of FN, ED-A, and ED-B in frozen sections from intestinal mucosa was determined by immunohistochemistry. The mRNA expression of the FN isoforms in control, CD, and fibrosis biopsies was quantified by real-time polymerase chain reaction (PCR). Integrin alpha5beta1 protein and mRNA expression was analyzed by fluorescence activated cell sorting (FACS) and PCR, respectively. RESULTS: Subtractive hybridization indicated differential regulation of FN isoform expression in CD. The immunohistochemical analysis of FN protein revealed a reduction of FN isoforms in inflamed CD mucosa compared to control mucosa. In CD fistulae, the ED-A and ED-B isoforms were virtually absent. In fibrotic mucosa, both proteins were increased. Real-time PCR showed a decrease of FN and ED-A expression during mucosal inflammation in CD in contrast to UC and a significant increase of FN and isoforms in CD fibrosis. No difference was found for protein and mRNA of integrin alpha5beta1 in control, CD, and fibrosis CLPF by FACS and PCR. CONCLUSION: Downregulated expression of migration-inducing FN-isoforms in contrast to unchanged FN receptor expression may contribute to the observed alterations of CD CLPF migration.     

Th1-mediated intestinal inflammation in Crohn's disease may be induced by activation of lamina propria lymphocytes through synergistic stimulation of interleukin-12 and interleukin-18 without T cell receptor engagement

OBJECTIVE: The development of T helper type 1 (Th1) CD4+ T cells in the intestinal mucosa is driven by interleukin (IL)-12 produced from activated macrophages and IL-18 produced from activated macrophages and epithelial cells. Each of these two cytokines is important for the mucosal response during intestinal inflammation, but their synergistic effect is not fully understood. To characterize the synergistic effect of IL-12 and IL-18 with respect to human intestinal inflammation, we assessed the effect of IL-12 and IL-18 on lamina propria lymphocytes from normal control subjects (LPL-NL) and patients with Crohn's disease (LPL-CD). METHODS: Expression of IL-12 receptor (IL-12R) beta1, beta2, and IL-18Ralpha in LPLs was analyzed by flow cytometry. The functional activity of IL- 12 and IL-18 was assessed by the effect of recombinant IL-12 and recombinant IL-18 on interferon-gamma production, the proliferative response, and the induction of IL-2R, IL-12R, and IL-18R of LPLs. RESULTS: IL-12Rbeta2 expression was significantly greater in LPL-CD compared with LPL-NL. LPL-NL demonstrated a proliferative response and a significant increase in interferon-gamma production and IL-2Ralpha expression when exposed to both IL- 12 and IL- 18, but neither IL- 12 nor IL-18 were able to induce this response on their own. However, IL-12 and IL-18 produced this response in LPL-CD when administered alone. Moreover, a more pronounced synergistic effect of IL-12 and IL-18 was observed in LPL-CD. The response normally observed after administration of IL-12 and IL-18 was significantly inhibited by anti-IL-2 and anti-IL-2Ralpha monoclonal antibody. Furthermore, IL-12 was observed to upregulate IL-18Ralpha expression in LPL-CD. CONCLUSIONS: These findings suggest that a combination of IL-12 and IL-18 in the absence of T cell receptor engagement may serve as a potent regulatory factor for LPL and contribute to the maintenance and enhancement of chronic inflammation in CD.     

Interleukin-12 and Th1 immune response in Crohn＇s disease： Pathogenetic relevance and therapeutic inplication

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory disorders of the gastrointestinal tract that share clinical and pathological characteristics. The most accredited hypothesis is that both CD and UC result from a deregulated mucosal immune response to normal constituents of the gut microflora. Evidence, however, indicates that the main pathological processes in these two diseases are distinct. In CD, the tissue-damaging inflammatory reaction is driven by activated type 1 helper T-cell (Th1), whereas a humoral response predominates in UC. Consistently, a marked accumulation of macrophages making interleukin (IL)-12, the major Th1-inducing factor, is seen in CD but not in UC mucosa. Preliminary studies also indicate that administration of a monoclonal antibody blocking the IL-12/p40 subunit can be useful to induce and maintain clinical remission in CD patients. Notably, the recently described IL-23 shares the p40 subunit with IL-12, raising the possibility that the clinical benefit of the anti-IL-12/p40 antibody in CD may also be due to the neutralization of IL-23 activity. This review summarizes the current information on the expression and functional role of IL-12 and IL-12-associated signaling pathways both in patients with CD and experimental models of colitis, thus emphasizing major differences between IL-12 and IL-23 activity on the development of intestinal inflammation.     

FOXP3在炎症性肠病患者外周血和肠黏膜中的表达特点

背景：炎症性肠病（IBD）的发病与一系列免疫异常有关。免疫反应受特定的免疫调节细胞调控，包括CD4^＋CD25^＋T细胞．而CD4^＋CD25^＋T细胞的发育和功能可能受FOXP3基因调控。目的：研究FOXP3的表达特点以及IBD时FOXP3表达的改变。方法：以免疫磁珠分离CD4^＋、CD4^＋CD25^＋和CD4^＋CD25^-T细胞。以逆转录聚合酶链反应（RT-PCR）和蛋白质印迹法检测IBD患者和非IBD对照外周血单个核细胞（PBMC）、肠固有层单个核细胞（LPMC）和肠黏膜组织中FOXP3的表达。结果：CD4^＋CD25^＋T细胞中FOXP3 mRNA的表达明显强于CD4^＋T细胞和未分离的PBMC或LPMC。T细胞受体（TCR）激活后，或经白细胞介素（IL）-2、IL-15作用后，PBMC或LPMC FOXP3 mRNA或蛋白表达明显增强。12例IBD中9例（75．0％）肠黏膜LPMC中检测到FOXP3 mRNA表达，高于对照肠黏膜的47．1％（8／17．P〉0．05）。未受刺激的IBD和对照肠黏膜组织中未检测到FOXP3 mRNA表达。结论：人类FOXP3的表达受T细胞活化影响。IBD患者肠黏膜LPMC中FOXP3 mRNA的表达率有增高的趋势．但与对照肠黏膜相比无显著差异．     

Interleukin-12 and Th1 immune response in Crohn''s disease: Pathogenetic relevance and therapeutic inplication

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory disorders of the gastrointestinal tract that share clinical and pathological characteristics.The most accredited hypothesis is that both CD and UC result from a deregulated mucosal immune response to normal constituents of the gut microflora. Evidence,however, indicates that the main pathological processes in these two diseases are distinct. In CD, the tissuedamaging inflammatory reaction is driven by activated type 1 helper T-cell (Th1), whereas a humoral response predominates in UC. Consistently, a marked accumulation of macrophages making interleukin (IL)-12, the major Th1-inducing factor, is seen in CD but not in UC mucosa.Preliminary studies also indicatethat administration of a monoclonal antibody blocking the IL-12/p40 subunit can be useful to induce and maintain clinical remission in CD patients. Notably, the recently described IL-23 shares the p40 subunit with IL-12, raising the possibility that the clinical benefit of the anti-IL-12/p40 antibody in CD may also be due to the neutralization of IL-23 activity. This review summarizes the current information on the expression and functional role of IL-12 and IL-12-associated signaling pathways both in patients with CD and experimental models of colitis, thus emphasizing major differences between IL-12 and IL-23 activity on the development of intestinal inflammation.     

Characterization of structures with T-lymphocyte aggregates in ileal villi of Crohn's disease

OBJECTIVES: Epithelioid granulomas with transmural inflammation are a characteristic histological feature in Crohn's disease (CD). However, these are not frequently detected by histopathological examination in the biopsy specimens. Here, we demonstrated unique structures with T-lymphocyte aggregates (TLAs) that were specifically found in ileal villi of CD. We characterized the histological and phenotypical features of these structures and assessed the diagnostic value of TLAs for CD. METHODS: Tissue samples were obtained from the inflamed and uninflamed areas of ileal and colonic mucosa of 32 patients with CD. For controls, mucosal samples were obtained from unaffected areas of 18 patients with colon cancer and inflamed and uninflamed areas of 12 patients with ulcerative colitis (UC). RESULTS: 1) In 21 of 32 cases of CD (66%), we found unique structures with lymphoid cell aggregates that were localized in villi of ileum. These structures were not detected in any normal or UC intestine. 2) These structures were composed mainly of T cells, and CD4+ CD45RO+ cells dominated. Neither B cells nor c-kit positive immature lymphocytes were found. Moreover, CD68 positive macrophages were demonstrated in these aggregates, and cells positive for interleukin 18, a pivotal cytokine for Th1 differentiation, were expressed. 3) The aggregates were detected in seven of 13 patients with CD in whom granuloma was not detected by precise histopathological examination. Furthermore, we detected TLAs even in the ilea of two of four CD patients (50%) whose affected lesions were limited to the colon. CONCLUSIONS: We demonstrated TLAs in intestinal villi that may contribute to the pathogenesis of CD. Detection of these lymphocyte aggregates is helpful for diagnosis of CD when granuloma is not found.     

骨桥蛋白在炎症性肠病患者结肠组织中的表达

背景：骨桥蛋白（OPN）是一种分泌型磷酸化糖蛋白,参与细胞信号转导,促进细胞黏附和迁移。近年研究发现炎症性肠病（IBD）患者血浆OPN水平升高,患者结肠黏膜中可检出OPN表达。目的：了解OPN在IBD患者结肠黏膜组织中的表达情况,探讨其在IBD发病机制中的作用。方法：以免疫组化半定量方法检测53例溃疡性结肠炎（UC）、62例克罗恩病（CD）和15例源自结肠腺瘤患者的正常结肠组织标本中OPN的表达。结果：OPN广泛表达于结肠黏膜上皮细胞和固有层渗出细胞。UC组和CD组结肠上皮细胞的OPN平均光密度值显著低于对照组（11．84±0．98和10．04±1．37对12．64±1．45,P〈0．05）,结肠黏膜固有层渗出细胞的OPN阳性细胞百分率则显著高于对照组（20．31％±4．50％和12．69％±3．06％对3．85％±0．66％,P〈0．001）。UC和CD患者的病情严重程度与结肠上皮细胞和固有层渗出细胞中的OPN表达量均无相关性。结论：OPN在IBD患者结肠黏膜上皮和同有层中的表达不一致,结肠上皮细胞中OPN表达下调可能与肠黏膜屏障功能受损有关,而黏膜固有层渗出细胞中OPN表达上调可能与免疫反应有关。     

PGC-1α在炎症性肠病肠黏膜组织中的表达及临床意义

目的:检测过氧化物酶体增殖物激活受体γ辅激活因子1α(PGC-1α)在炎症性肠病(inflammatory bowel disease,IBD)患者肠黏膜的表达水平,探讨其在IBD患者肠黏膜组织中的作用.方法:收集15例溃疡性结肠炎(Ulcerative colitis,UC)患者、17例克罗恩病(Crohn’s disease,CD)患者炎性肠黏膜活检标本及14例正常对照者内镜肠黏膜标本,采用免疫组织化学染色技术分析PGC-1α蛋白在肠黏膜中的原位表达,荧光定量PCR技术检测肠黏膜内PGC-1αmRNA的表达水平.结果:免疫组织化学分析显示:PGC-1α蛋白在正常肠黏膜上皮细胞内表达较多,黏膜固有层细胞内表达较少.与正常对照组相比,PGC-1α蛋白在UC患者肠黏膜上皮细胞内表达量明显减少,而肠黏膜固有层细胞内表达增加,PGC-1α蛋白在CD患者肠黏膜组织内表达量无明显差异.荧光定量PCR分析显示:UC患者炎症肠黏膜组织内PGC-1αmRNA表达水平显著低于正常对照组(0.48±0.15vs1.59±0.38,P<0.05),CD患者炎症肠黏膜组织内PGC-1αmRNA表达水平与正常对照组相比差异无统计学意义(1.55±0.47vs1.59±0.38,P>0.05).结论:与正常对照组相比,PGC-1α在UC炎症肠黏膜组织内表达水平降低,而在CD炎症肠黏膜中表达无明显差异,提示PGC-1α可能参与了UC发生发展过程.     

T-cell co-stimulatory molecules are upregulated on intestinal macrophages from inflammatory bowel disease mucosa.

BACKGROUND AND AIMS: Macrophages play an important role during mucosal inflammation in inflammatory bowel disease (IBD). As the co-stimulatory molecules B7-1 (CD80) and B7-2 (CD86) play an integral role in the activation of T cells by antigen-presenting cells (APC) we investigated the surface expression of B7-1 and B7-2 on colonic macrophages from normal and IBD mucosa. METHODS: Intestinal macrophages were isolated from biopsies of 13 control persons and 14 patients with IBD (seven with Crohn's disease (CD); and seven with ulcerative colitis (UC)). Cells were characterized by triple fluorescence flow cytometrical analysis using CD33 as macrophage marker. RESULTS: The expression of B7-1 (CD80) (9.2% +/- 4.2%) and B7-2 (CD86) (15.1% +/- 7.3%) was low on colonic macrophages from normal mucosa, indicating only a low antigen presenting potential. However, on macrophages from IBD colon there was a significant increase in the expression of co-stimulatory molecules (CD80, 33.8% +/- 8.9%, P = 0.00005 vs. control; CD86, 39.9% +/- 8.8%, P = 0.00002). There was no significant difference between CD and UC in the expression of CD80 (CD, 31.3% +/- 6.7%; UC, 34.4% +/- 13.3%) and CD86 (CD, 41.9% +/- 3.8%; UC, 35.6% +/- 13.8%). While in normal mucosa only 10.6% +/- 4.9% of the macrophages expressed CD14, more than 90% of the CD86/CD80 positive cells of the inflamed mucosa were positive for CD14. CONCLUSION: Colonic macrophages from normal mucosa rarely express the co-stimulatory molecules CD80 and CD86. In IBD a new macrophage population is found with high expression of co-stimulatory molecules presumably responsible for the perpetuated immune response.     

Polarized production of T-helper cell type 1 cells in Peyer's patches in Crohn's disease

BACKGROUND/AIMS: Although Peyer's patches (PPs) serve as important antigen-sampling sites for the immune system, surprisingly little attention has been paid to their associations with the onset of Crohn's disease (CD) as antigen entry sites. To examine the immunological events in PPs, we performed functional and phenotypical studies on PP cells, the lamina propria cells in the colonic mucosa and peripheral blood mononuclear cells (PBMC) in inflammatory bowel disease. PATIENTS: The subjects were 9 children and adolescents with active CD, 9 with inactive CD, 11 with active ulcerative colitis (UC), and 22 normal controls. METHODS: The cytokine profile in PPs and lamina propria was performed through Elispot assay and RT-PCR. PP mononuclear cells and PBMC from the subjects were analyzed by flow cytometry using monoclonal antibodies to interferon-gamma and interleukin-4, and CC chemokine receptors (CCR) 4 and 5. RESULTS: Th1 together with Tc1 cells were dominant in PPs in the active phase of CD, but not in inactive CD, UC, or normal controls. They did not actually produce interferon-gamma, however they have abundant mRNA of the cytokine. Substantial levels of CCR5 ligands, MIP-1alpha and RANTES mRNA were found in the inflamed intestinal mucosa in CD. CONCLUSIONS: It is conceivable that PPs in the terminal ileum in CD may initially sample luminal antigens where Th1-type memory cells are activated which migrate to the peripheral intestinal mucosa. Those immunological changes may not be related to the etiology of UC.     

A controlled study of colonic immune activity and beta7+ blood T lymphocytes in patients with irritable bowel syndrome.

BACKGROUND & AIMS: The mechanisms behind irritable bowel syndrome (IBS) are incompletely understood. Recently several studies have suggested a low-grade colonic inflammation as initiator of the gut dysfunctions recorded in this patient group. The aim of this study was to characterize the phenotype and homing properties of colonic and peripheral blood lymphocytes in patients with IBS. METHODS: Patients with IBS (n=33), defined by the Rome II criteria, were compared with UC patients (n=23) and control subjects (n=15) without gastrointestinal symptoms. Colonic and peripheral blood lymphocytes were analyzed by flow cytometry. Secretion of IFN-gamma from intestinal biopsies was determined by enzyme-linked immunosorbent assay, and immunohistochemical staining of colonic biopsies was performed. RESULTS: IBS patients displayed an increased frequency of peripheral blood CD4+ and CD8+ T cells expressing the gut homing integrin beta7. Accordingly, IBS and UC patients had an augmented frequency of lamina propria CD8+ T cells in the ascending colon as compared with control subjects. The frequency of intestinal T cells expressing integrin beta7+ was unaltered in IBS and UC patients, although the expression of mucosal addressin cell adhesion molecule-1+ endothelium, the ligand for integrin beta7, was increased in the ascending colon of IBS and UC patients as compared with control subjects. CONCLUSIONS: Patients with IBS exhibit an enhanced immune activity in the gut and an increased frequency of integrin beta7+ T lymphocytes in the peripheral blood. Our data further support the hypothesis of IBS being at least partially an inflammatory disorder.     

Expression of osteopontin at sites of bone erosion in a murine experimental arthritis model of collagen-induced arthritis: possible involvement of osteopontin in bone destruction in arthritis

OBJECTIVE: To investigate the involvement of osteopontin (OPN) in bone destruction in a murine experimental arthritis model of collagen-induced arthritis (CIA). METHODS: The expression of OPN was examined at both the messenger RNA (mRNA) and protein levels in various arthritic lesions in mice with CIA by in situ hybridization and immunohistochemistry, respectively. In addition, the expression of alpha(v)beta3 integrin, a receptor for OPN, the ligation of which is thought to be essential for bone resorption by osteoclasts, was examined by immunohistochemistry. Plasma concentrations of OPN were measured at different time points in the course of CIA by enzyme-linked immunosorbent assay. RESULTS: OPN mRNA was detected mainly at sites of bone erosion in arthritic lesions, where activated osteoclasts were present; OPN protein was also detected at sites of bone erosion. In the arthritic synovium, OPN was predominantly expressed in the synovial lining layer, but not in lymphoid aggregates. In addition, alpha(v)beta3 integrin was detected coincident with OPN at sites of bone erosion (bone-pannus junction). Plasma OPN levels were markedly elevated at the time points that corresponded to arthritis flares, and higher levels were maintained during the progression of arthritis. CONCLUSION: OPN may mediate bone resorption by osteoclasts in arthritis through ligation with its receptor, alpha(v)beta3 integrin. OPN may be a useful therapeutic target molecule in the prevention of bone destruction in arthritis.