IL-21/IL-21R信号在IBD病变形成机制中作用的研究进展

炎症性肠病(Inflammatory bowel disease,IBD)的发病机制至今尚不明确,普遍认为是由肠黏膜免疫调节异常、持续性肠道感染、肠黏膜屏障缺损、遗传和环境等多种因素相互作用导致的。近年来,研究发现IBD患者血清中IL-21水平异常升高,提示IL-21/IL-21R信号可能在IBD的病变形成中发挥重要作用。IL-21是一种重要的具有多重生物学功能的细胞因子,通过对CD4+T细胞、CD8+T细胞、Th17细胞、B细胞、巨噬细胞、树突状细胞等多种细胞产生影响,从而参与IBD的发生发展。本文就IL-21/IL-21R信号在炎症性肠病发病机制中的研究进展进行综述。     

间充质干细胞对Th17/Treg平衡的影响及与IBD的关系

辅助性T细胞17（Th17）/调节性T细胞（Treg）失衡是炎症性肠病（IBD）发病的重要因素,纠正Th17/Treg细胞失衡可以减缓或抑制IBD的发生发展,成为治疗IBD的靶点。间充质干细胞具有抗炎及免疫调节功能,通过可溶性因子、细胞接触及外泌体的方式调节适应性和先天性免疫,纠正Th17/Treg失衡缓解IBD,这给IBD的治疗提供新的方向。目前,MSCs和IBD的关系研究较少,本文综述了MSCs调节Th17/Treg平衡及与IBD的关系。     

益生菌对炎症性肠病幼鼠 Th17细胞的调节作用

目的观察鼠李糖乳杆菌(LGG)对炎症性肠病(IBD)幼鼠结肠白细胞介素-17A (IL-17A)水平的影响,探讨益生菌对Th17细胞的调节作用。方法 36只健康雄性SD幼鼠随机分4组:空白对照组、LGG对照组各8只,IBD组、IBD-LGG组各10只。利用2,4,6-三硝基苯磺酸(TNBS)诱导幼鼠IBD模型,观察一般状况、IBD疾病活动指数评分。第8天处死所有幼鼠,留取结肠标本,观察病理改变并采用免疫组织化学法测定结肠组织IL-17A的表达。结果相比两对照组,IBD组、IBD-LGG组幼鼠一般状态差,IBD-LGG组便性状及隐血较IBD组缓解;IBD组、IBD-LGG组幼鼠结肠组织均见炎症改变,但IBD-LGG组较轻。IBD-LGG组DAI评分、IL-17A水平均低于IBD组,差异有统计学意义(Ps0.05)。结论益生菌可减轻IBD幼鼠肠道炎症,其机制可能与益生菌调节Th17细胞进而调控IL-17A表达有关。     

粪菌移植在儿童炎症性肠病中的应用

炎症性肠病(IBD)是一种病因尚不明确的非特异性肠道炎症性疾病。越来越多的证据表明肠道菌群失调与IBD的发生发展密切相关。粪菌移植是通过各种方式将健康捐赠者的粪便菌群移植入患者消化道内,旨在重建患者肠道菌群从而达到对肠道内外疾病治疗的目的。肠道微生物稳态及失调在疾病发生发展中发挥作用,其中包括炎症性肠病(IBD)。越来越多的研究报道了FMT在IBD中的治疗作用,现主要阐述粪菌移植在儿童IBD中的应用。     

白细胞介素23受体、白细胞介素17A在炎症性肠病患者中的表达 及临床意义

目的:通过检测白细胞介素23受体(IL-23R)及白细胞介素17A(IL-17A)在炎症性肠病(IBD)患者肠黏膜及血清中的表达水平,探讨其在IBD发病过程中的作用及意义。方法:收集32例克罗恩病(CD)患者、29例溃疡性结肠炎(UC)患者及27例对照者的内镜肠黏膜活检标本,采用荧光定量PCR技术检测肠黏膜内IL-23R、IL-17AmRNA的表达情况,免疫组化技术分析IL-23R、IL-17A在肠黏膜中的原位表达。结果:与健康对照组相比,CD及UC患者肠黏膜组织内IL-23R mRNA表达显著增高(P<0.05),CD及UC组间的表达量差异无统计学意义(P>0.05)。CD及UC患者肠黏膜组织内IL-17A mRNA表达显著增高(P<0.05),CD组肠黏膜组织内IL-17AmRNA表达显著高于UC组(P<0.05)。免疫组化分析显示IL-23R阳性细胞在CD与UC肠黏膜固有层内有较多表达,较正常黏膜内的肠上皮细胞相比,CD及UC患者肠黏膜IL-23R蛋白表达量最著增高(P<0.05),UC及CD组间的表达量差异无统计学意义(P>0.05)。IL-17A阳性细胞在CD与UC肠黏膜固有层内有较多表达,较正常黏膜内的肠上皮细胞相比,CD及UC患者肠黏膜IL-17A蛋白表达量最著增高(P<0.05)。结论:IL-23R及IL-17A在IBD患者肠黏膜中表达显著增高,提示IL-23R及IL-17A表达异常与IBD的发生发展密切相关,有可能成为IBD治疗的新靶点。     

潘氏细胞与炎症性肠病研究进展

<正>潘氏细胞(paneth cells,PCs)是小肠腺的特征性细胞,可分泌防御素等多种抗菌物质,抑制肠道细菌过度繁殖,在维持肠道内稳态、参与固有免疫方面发挥重要作用。炎症性肠病(inflammatory bowel disease,IBD)主要包括克罗恩病(crohn's disease,CD)和溃疡性结肠炎(ulcerative colitis,UC),其发病机制复杂,受环境因素、遗传因素及肠道菌群等多种因素的影响,主要表现为肠道免疫系统对肠道菌群的不良免疫反应。近年来,有关PCs与IBD的相关性研究较多,现本文就其研究进展作一综述如下。     

炎症性肠病与肠道微生态的研究进展

炎症性肠病(inflammatoryboweldisease,IBD)是一种肠道慢性炎症性疾病,其发病机制尚不清楚。然而,IBD的发病率不断上升给患者及其家属带来了巨大的经济负担,需要找到积极有效的治疗方法来帮助患者。最新的观点认为,宿主和肠道微生物之间的平衡被打破会触发遗传易感个体的免疫炎症反应。肠道菌群失调在炎症性肠病的发病及发展过程中起着重要的作用。临床研究发现,IBD患者肠道菌群失调程度不同,而联合应用益生菌可以改善这些患者的症状。越来越多的研究者密切关注肠道菌群与IBD的关系,并进行了深入的基础和临床研究。本文从肠道菌群对IBD的生理影响以及益生菌和粪便细菌移植等方面进行综述。     

益生菌在炎症性肠病中的治疗作用

炎症性肠病(inflammatory bowel disease,IBD)包括溃疡性结肠炎(ulcerative colitis,UC)和克罗恩病(Crohn’s disease,CD)。随着对肠道微生物群在IBD发病机制中作用的认识不断深入,近年来益生菌广泛应用于IBD治疗。大量临床试验结果表明,益生菌治疗IBD的疗效主要体现在对UC和贮袋炎的治疗,对CD的疗效不明确。益生菌治疗IBD可能通过促进肠道微生物群平衡、改善肠道屏障功能、调节肠道黏膜免疫及营养物质代谢等途径。     

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。     

不同途径下MIMP对炎症性肠病小鼠的肠屏障及炎症因子的改善作用

目的通过葡聚糖硫酸钠(DSS)诱导小鼠炎症性肠病(inflammatory bowel disease,IBD)模型并观察不同途经下乳酸杆菌微小膜蛋白(MIMP)对炎症性肠病小鼠的肠炎的影响。方法 C57BL/6小鼠40只根据DSS和MIMP不同的干预组合将其分为4组:诱导肠炎+MIMP腹腔注射组(n=10)、诱导肠炎+MIMP灌胃组(n=10)、单纯诱导肠炎组(n=10)、空白对照组(n=10),DSS干预浓度为2.5%。干预期间,观察小鼠体重变化情况,腹泻、血便、死亡等发生率,各组小鼠活体肠道通透性差异,比较肠道长度及肠上皮组织病理学改变,应用荧光定量PCR反应观察各组小鼠肠道中的炎症因子的表达,应用免疫组织化学染色观察各组小鼠肠道上皮中IL-23的表达。结果 MIMP腹腔注射组以及灌胃组小鼠整体情况较好,体重减轻程度轻,腹泻、便血及死亡发生率低;MIMP干预可显著改善肠道通透性(P0.05),并降低肠道萎缩程度,同时降低小鼠肠道病理评分及组织学评分,可显著降低小鼠肠道中促炎性细胞因子(IL-23p19、IL-17A、IL-12p40)的表达(P0.05),并提高抑炎性细胞因子(IL-10)的表达(P0.05),免疫组化显示MIMP可显著降低小鼠肠上皮细胞中IL-23的表达水平。结论 MIMP腹腔注射及灌胃对IBD小鼠的炎症状态及肠道屏障功能有显著的改善作用,并可显著降低促炎性细胞因子的表达,提高抑炎性细胞因子的表达。     

Synergy of IL-23 and Th17 Cytokines: New Light on Inflammatory Bowel Disease

Inflammatory bowel diseases (IBDs), including Crohn’s disease and ulcerative colitis, involve an interplay between host genetics and environmental factors including intestinal microbiota. Animal models of IBD have indicated that chronic inflammation can result from over-production of inflammatory responses or deficiencies in key negative regulatory pathways. Recent research advances in both T-helper 1 (Th1) and T-helper 17 (Th17) effect responses have offered new insights on the induction and regulation of mucosal immunity which is linked to the development of IBD. Th17 cytokines, such as IL-17 and IL-22, in combination with IL-23, play crucial roles in intestinal protection and homeostasis. IL-23 is expressed in gut mucosa and tends to orchestrate T-cell-independent pathways of intestinal inflammation as well as T cell dependent pathways mediated by cytokines produced by Th1 and Th17 cells. Th17 cells, generally found to be proinflammatory, have specific functions in host defense against infection by recruiting neutrophils and macrophages to infected tissues. Here we will review emerging data on those cytokines and their related regulatory networks that appear to govern the complex development of chronic intestinal inflammation; we will focus on how IL-23 and Th17 cytokines act coordinately to influence the balance between tolerance and immunity in the intestine.     

Th17-related cytokines in inflammatory bowel diseases: friends or foes?

T helper (Th)17 cells and other interleukin (IL)-17-producing cells are supposed to play critical roles in several human immune-mediated diseases, including Crohn's disease (CD) and ulcerative colitis (UC), the main forms of inflammatory bowel diseases (IBD) in man. Th17 cells infiltrate massively the inflamed intestine of IBD patients and in vitro and in vivo studies have shown that Th17-type cytokines may trigger and amplify multiple inflammatory pathways. Nonetheless, some Th17-related cytokines, such as interleukin (IL)-17A and IL-22, may target gut epithelial cells and promote the activation of counter-regulatory mechanisms. This observation together with the demonstration that Th17 cells are not stable and can be converted into either regulatory T cells or Th1 cells if stimulated by immune-suppressive (e.g. TGF-β1) or inflammatory (e.g. IL-12, IL-23) cytokines have contributed to advance our understanding of mechanisms that regulate mucosal homeostasis and inflammation in the gut.     

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.     

Th17细胞的分化、调节及其主要细胞因子和功能

近几年来以分泌白介素17(interleukin 17,IL-17)为特征的辅助性T细胞Th17(T help cell 17,Th17)细胞被认为是有区别于Th1(T help cell 1,Th1)、Th2(T help cell 2,Th2)新型的细胞亚群,它的发现改变了以往人们只将Th细胞分为Th1、Th2的传统分类认识。Th17细胞参与了自身免疫疾病、肿瘤的发生及机体各种炎症的发病机制,其分泌的细胞因子在生物学功能中发挥了极其重要的作用。同时Th17细胞的活化需要各种转化生长因子、IL-6(interleukin 6,IL-6)、IL-23(interleukin 23,IL-23)等细胞因子的参与,活化的Th17细胞同时再进一步的促进各种细胞因子的分泌,以通过分泌IL-17、IL-21(interleukin 21,IL-21)、IL-22(interleukin22,IL-22)、IL-26(interleukin 26,IL-26)、肿瘤坏死因子(tumor necrosis factor,TNF)α等细胞因子导致机体炎症等各种疾病的发生。     

Treatment with IL-27 attenuates experimental colitis through the suppression of the development of IL-17-producing T helper cells

Inflammatory bowel disease (IBD) represents a group of chronic inflammatory diseases characterized by inflammation and relapsing gastrointestinal disorders. Recent studies have shown that Th17 cells, which are well known as key mediators of chronic inflammation, have a pivotal role in onset and development of IBD in humans and mice, alike. In recent years, it has been reported that IL-27, which is an IL-12-related heterodimeric cytokine consisting of EBI3 and p28 subunits, act directly on naive T cells to suppress the differentiation of Th17 cells. However, effects of exogenous IL-27 on the IBD are not well elucidated. To clarify the suppressive effect of IL-27 treatment on IBD, we applied the flexible linking method to EBI3 and p28 subunits and generated a single-chain human IL-27 (scIL-27). scIL-27 inhibited xenogenic mouse Th17 cell differentiation in vitro, indicating that scIL-27 also acts in mouse immune systems. In a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced mouse acute colitis model, subcutaneous scIL-27 treatment significantly improved the colon length, extent of necrosis, and ulceration and thickened epithelium and several pathological scores in a dose-dependent manner. scIL-27 clearly suppressed several inflammatory cytokines, including IL-17, in inflamed colon, except for anti-inflammatory cytokine IL-10. The mesenteric lymph node cells from scIL-27-treated mice also exhibited a reduced inflammatory response and, furthermore, a lower population of Th17 cells than those of PBS-treated mice. Finally, we showed the therapeutic efficacy of scIL-27 on TNBS-induced colitis even after active colitis was established. These results suggest new possible therapeutic approaches for IBD, including disorders such as Crohn's disease and ulcerative colitis.     

Faecalibacterium prausnitzii Inhibits Interleukin-17 to Ameliorate Colorectal Colitis in Rats

Background and Aims

It has been shown that Faecalibacterium prausnitzii (F. prausnitzii), one of the dominant intestinal bacterial flora, may protect colonic mucosa against the development of inflammation and subsequent inflammatory bowel disease (IBD), with the underlying mechanisms being unclear.

Methods

The impacts of F. prausnitzii and its metabolites on IL-23/Th17/IL-17 pathway markers were determined in human monocytes and a rat model of colitis induced by 2,4,6-trinitrobenzene sulfonic acid. F. prausnitzii and its culture medium (containing complete metabolites) were used to treat the rats in vivo, as well as rat splenocytes and human monocytes in vitro. Inflammatory cytokines were measured in colon tissue, plasma and cell culture medium.

Results

The culture supernatant of F. prausnitzii increased plasma anti-Th17 cytokines (IL-10 and IL-12)and suppressed IL-17 levels in both plasma and colonic mucosa, with ameliorated colonic colitis lesions. This inhibition of IL-17 release has also been observed in both rat splenocytes and human venous monocytes in vitro. The culture supernatant of F. prausnitzii also suppressed Th17 cell differentiation induced by cytokines (TGF-ß and IL-6) and bone marrow-derived dendritic cells (BMDCs) in vitro. The metabolites of F. prausnitzii in the culture supernatant exert a stronger anti-inflammatory effect than the bacterium itself. F. prausnitzii protected the colon mucosa against the development of IBD by its metabolites, suggesting a promising potential for the use of F. prausnitzii and its metabolic products in the treatment of IBD.     

The opposing roles of IL-21 and TGFβ1 in chronic inflammatory bowel disease

There are large numbers of T-cells in the mucosa of the intestine in healthy individuals. The stimulus for their presence is the normal gut microbiota. For unknown reasons, in patients with IBD (inflammatory bowel disease), there is inappropriate and chronic activation of mucosal T-cells which leads to gut damage and severe morbidity. In one form of IBD, namely Crohn's disease, the T-cells are probably responding to the microbiota. T-cell survival in the gut wall is dependent on pro-inflammatory cytokines and antibody-mediated inhibition of one of these cytokines, TNFα (tumour necrosis factor α), has shown efficacy in patients, thus encouraging investigations of other ways to control mucosal T-cell responses. In the present paper, we give a brief review of T-cell immunology in IBD and then discuss how two particular cytokines, namely IL-21 (interleukin 21), which is generally pro-inflammatory and important in gut T-cell survival and in maintaining Th17 cells, and TGFβ1 (transforming growth factor β1), which is generally immunosuppressive, play opposing roles in gut inflammation.     

The IL23R R381Q gene variant protects against immune-mediated diseases by impairing IL-23-induced Th17 effector response in humans

IL-23 and Th17 cells are key players in tissue immunosurveillance and are implicated in human immune-mediated diseases. Genome-wide association studies have shown that the IL23R R381Q gene variant protects against psoriasis, Crohn's disease and ankylosing spondylitis. We investigated the immunological consequences of the protective IL23R R381Q gene variant in healthy donors. The IL23R R381Q gene variant had no major effect on Th17 cell differentiation as the frequency of circulating Th17 cells was similar in carriers of the IL23R protective (A) and common (G) allele. Accordingly, Th17 cells generated from A and G donors produced similar amounts of Th17 cytokines. However, IL-23-mediated Th17 cell effector function was impaired, as Th17 cells from A allele carriers had significantly reduced IL-23-induced IL-17A production and STAT3 phosphorylation compared to G allele carriers. Our functional analysis of a human disease-associated gene variant demonstrates that IL23R R381Q exerts its protective effects through selective attenuation of IL-23-induced Th17 cell effector function without interfering with Th17 differentiation, and highlights its importance in the protection against IL-23-induced tissue pathologies.