Mucosal immunology and bacterial handling in the intestine

The mucosal immune system has the very difficult task to protect against invaders and to promote tolerance toward food antigens and the microbiota. These activities are achieved via a complex interaction between immune cells and the local microenvironment. Under the unperturbed (steady-state) condition the immune system is set toward the activation of tolerogenic responses. During infection the immune system is prompted to initiate immunity. When these two activities are not coordinated, inflammatory conditions may arise. In this review I will summarize the characteristic features of the mucosal immune system and its interaction with the microbiota.     

酒精性肝病的免疫学研究进展

酒精性肝病是由于长期大量饮酒所致的肝脏疾病.乙醇代谢与脂质过氧化产物加合物的形成及诱发的免疫反应、库普弗细胞激活产生的免疫应答、T淋巴细胞参与的反应等是免疫反应在酒精性肝病发生、发展的主要表现.     

Recent advances in the endoscopic assessment of ulcerative colitis

Endoscopic assessment of the severity and extent of inflammation as well as the presence of neoplastic lesions is integral to the management of ulcerative colitis (UC). Numerous scoring systems to assess endoscopic severity indicate that a perfect scoring system is still lacking. Many of the scoring systems were designed in the era of standard-definition white-light endoscopy. The resolution and details provided by the new-generation endoscopes and high-definition equipment of both mucosal pattern and vascular pattern mandates a fresh look at endoscopic scoring in UC. In this context, we describe some of the scoring systems recently designed using novel endoscopic techniques. Current definitions of mucosal healing do not completely reflect histologic healing but this gap is being closed rapidly by novel endoscopic techniques with high-definition images that can be optically and digitally enhanced. The best technique to detect dysplasia in UC is still widely debated. New endoscopic resection techniques may now be able to limit the number of colectomies that need to be performed in the presence of dysplasia owing to improvement in performing local resection.     

Helminth infections and intestinal inflammation

Evidence from epidemiological studies indicates an inverse correlation between the incidence of certain immune-mediated diseases, including inflammatory bowel diseases （IBD）, and exposure to helminths. Helminth parasites are the classic inducers of Th2 responses. The Th2-polarized T cell response driven by helminth infection has been linked to the attenuation of some damaging Th1 driven inflammatory responses, preventing some Th1-mediated autoimmune diseases in the host, including experimentally induced colitis. Helminth parasites （the porcine whipworm, Trichuris suis ） have been tested for treating IBD patients, resulting in clinical amelioration of the disease. As a result, there is a great deal of interest in the research community in exploring the therapeutic use of helminth parasites for the control of immune-mediated diseases, including IBD. However, recent studies have provided evidence indicating the exacerbating effects of helminths on bacterial as well as non-infectious colitis in animal models. Therefore, a better understanding of mechanisms by which helminths modulate host immune responses in the gut may reveal novel, more effective and safer approaches to helminth-based therapy of IBD.     

Etiopathogenesis of inflammatory bowel diseases

Theories explaining the etiopathogenesis of inflammatory bowel disease (IBD) have been proposed ever since Crohn's disease (CD) and ulcerative colitis (UC) were recognized as the two major forms of the disease. Although the exact cause(s) and mechanisms of tissue damage in CD and UC have yet to be completely understood, enough progress has occurred to accept the following hypothesis as valid: IBD is an inappropriate immune response that occurs in genetically susceptible individuals as the result of a complex interaction among environmental factors, microbial factors, and the intestinal immune system. Among an almost endless list of environmental factors, smoking has been identified as a risk factor for CD and a protective factor for UC. Among microbial factors, no convincing evidence indicates that classical infectious agents cause IBD, while mounting evidence points to an abnormal immune response against the normal enteric flora as being of central importance. Gut inflammation is mediated by cells of the innate as well as adaptive immune systems, with the additional contribution of non-immune cells, such as epithelial, mesenchymal and endothelial cells, and platelets.     

Colorectal endoscopic submucosal dissection: Recent technical advances for safe and successful procedures

Endoscopic submucosal dissection (ESD) is very useful in en bloc resection of large superficial colorectal tumors but is a technically difficult procedure because the colonic wall is thin and endoscopic maneuverability is poor because of colonic flexure and extensibility. A high risk of perforation has been reported in colorectal ESD. To prevent complications such as perforation and unexpected bleeding, it is crucial to ensure good visualization of the submucosal layer by creating a mucosal flap, which is an exfoliated mucosa for inserting the tip of the endoscope under it. The creation of a mucosal flap is often technically difficult; however, various types of equipment, appropriate strategy, and novel procedures including our clip-flap method, appear to facilitate mucosal flap creation, improving the safety and success rate of ESD. Favorable treatment outcomes with colorectal ESD have already been reported in many advanced institutions, and appropriate understanding of techniques and development of training systems are required for world-wide standardization of colorectal ESD. Here, we describe recent technical advances for safe and successful colorectal ESD.     

高通量测序在鸟类肠道微生物中的研究进展

鸟类作为分布广泛、种群数量庞大和高度多样化的物种之一,在病原体传播中发挥了重要作用。本文综述了基于高通量测序技术的3种测序策略(16S rDNA测序、宏基因组测序和宏转录组测序)的特点及其在鸟类肠道菌群多样性、抗生素抗性基因和病原微生物发现中的应用,并对未来发展趋势进行了展望。     

乙型肝炎e抗原与免疫耐受研究进展

乙型病毒性肝炎是世界范围内广泛传播的严重危害人类健康的传染病,全球约有4亿慢性乙型肝炎(chronichepatitis B,CHB)患者[1].CHB是引起肝硬化和肝细胞癌(hepatocellular carcinoma,HCC)的主要原因[2].从HBV感染人体的自然史来看,CHB一般会经历较长的免疫耐受期,此期患者表现为血清乙型肝炎病毒表面抗原(HBsAg)和乙型肝炎e抗原(HBeAg)阳性,HBV复制活跃,HBV DNA滴度较高(＞ 105拷贝/ml),血清丙氨酸转氨酶(ALT)水平正常,无临床症状,肝脏病理表现为无损伤或仅有轻微炎症损伤[3-4].     

呼吸道黏膜免疫的研究进展

呼吸道黏膜免疫除了传统的T细胞、B细胞、NK细胞等淋巴细胞参与外,目前认为还有多种重要的细胞和分子如支气管上皮细胞、M细胞、γδT细胞、树突状细胞及分泌型IgA等参与了呼吸道黏膜免疫并发挥重要作用,现已日益受到人们的关注,本文就此作一综述。     

CpG寡核苷酸作为黏膜佐剂的研究进展

含未甲基化的CpG二核苷酸的寡聚脱氧核苷酸模体(CpG ODN)具有很强的黏膜佐剂活性,已成为近年来的研究热点之一。应用CpG ODN与各种病毒和细菌抗原进行了大量实验研究,所涉及的黏膜免疫途径包括滴鼻、口服和生殖道。CpG ODN可与传统的黏膜佐剂CT和LT产生协同效应,对人体无毒副作用,是一种极具应用前景的黏膜佐剂。目前认为,CpG ODN的佐剂效应发挥与TLR9识别和后续的一系列信号转导密切相关。     

粘膜疫苗在胃肠道感染性疾病中的应用

肠粘膜疫苗是目前预防和治疗幽门螺杆菌感染(H．pylori)、各种肠道感染等消化系统疾病的新方法,并在治疗上取得了较好的疗效,此文简要综述当前研制的粘膜疫苗在胃肠道感染疾病中的应用。     

Intestinal microbiota in inflammatory bowel disease： Friend of foe？

Inflammatory bowel disease(IBD) arises from disruption of immune tolerance to the gut commensal microbiota,leading to chronic intestinal inflammation and mucosal damage in genetically predisposed hosts.In healthy individuals the intestinal microbiota have a symbiotic relationship with the host organism and possess important and unique functions,including a metabolic function(i.e.digestion of dietary compounds and xenobiotics,fermentation of undigestible carbohydrates with production of short chain fatty aci...     

免疫系统的衰老及其机制

免疫系统随着年龄的增加而功能退化,出现免疫系统衰老.免疫系统衰老与老年人群感染的易感性、疫苗的低效性、自身免疫性疾病增加以及肿瘤多发性密切相关.免疫系统衰老的特征表现为细胞介导的免疫功能下降以及抗体介导的体液免疫应答的降低.在衰老过程中,T细胞和B细胞功能的下降与先天性免疫系统功能的降低同时存在.本文就免疫系统随年龄衰老的改变及其内在机制进行综述.     

Non-coeliac gluten/wheat sensitivity: advances in knowledge and relevant questions

Introduction: Non-coeliac gluten/wheat sensitivity (NCG/WS) is a syndrome characterized by intestinal and extra-intestinal symptoms occurring a few hours or days after the ingestion of gluten and wheat proteins in patients testing negative for coeliac disease and wheat allergy.

Areas covered: The present review deals with recent scientific acquisitions of this gluten-related syndrome, including pathogenetic mechanisms, clinical picture, symptom score, biomarkers and double-blind placebo-controlled trial for diagnosis, and treatment. The methodology used was a literature search on NCG/WS using Medline and Premedline from 1970 to August 2016.

Expert commentary: We discussed the pathogenesis of symptom generation and altered gut physiology in NCG/WS. Possible mechanisms include innate and adaptive immune activation, impaired intestinal epithelial barrier and changes in gut microbiome. These interlinked factors may be exploited for their clinical relevance as possible biomarkers. A systemic immune response to microbial and wheat antigens, together with intestinal cell damage, occurs in patients with NCG/WS. Due to the lack of established biomarkers, it is mandatory to validate the diagnosis of the syndrome by means of a well-defined work-up involving dietary challenge. Finally, dietary and other therapeutic indications have been thoroughly reviewed.     

Recent advances and remaining gaps in our knowledge of associations between gut microbiota and human health

The complex gut microbial flora harbored by individuals （microbiota） has long been proposed to contribute to intestinal health as well as disease. Preand probiotic products aimed at improving health by modifying microbiota composition have already become widely available and acceptance of these products appears to be on the rise. However, although required for the development of effective microbiota based interventions, our basic understanding of microbiota variation on a population level and its dynamics within individuals is still rudimentary. Powerful new parallel sequence technologies combined with other efficient molecular microbiota analysis methods now allow for comprehensive analysis of microbiota composition in large human populations. Recent findings in the field strongly suggest that microbiota contributes to the development of obesity, atopic diseases, inflammatory bowel diseases and intestinal cancers. Through the ongoing National Institutes of Health Roadmap ＇Human Microbiome Project＇ and similar projects in other parts of the world, a large coordinated effort is currently underway to study how microbiota can impact human health. Translating findings from these studies into effective interventions that can improve health, possibly personalized based on an individuals existing microbiota, will be the task for the next decade（s）.     

Recent advances in schistosomiasis

Schistosomiasis is a major parasitic disease, affecting nearly 200 million persons, worldwide. Major advances in our knowledge-in terms of pathogenesis, improved diagnosis, therapeutics (both drugs and strategies), and morbidity assessment-now make schistosomiasis a curable, often preventable disease. In contrast to most other illnesses, most schistosomiasis pathology appears to be reversible over time. For the future, several promising vaccine candidates are already in phase-I or phase-II testing. On the other hand, the range of this disease has been increasing, as water resources are developed in several newly industrialized countries and much of schistosomiasis in sub-Saharan Africa remains largely untreated.