Dendritic cells in intestinal immune regulation

A breakdown in intestinal homeostasis can result in chronic inflammatory diseases of the gut including inflammatory bowel disease, coeliac disease and allergy. Dendritic cells, through their ability to orchestrate protective immunity and immune tolerance in the host, have a key role in shaping the intestinal immune response. The mechanisms through which dendritic cells can respond to environmental cues in the intestine and select appropriate immune responses have until recently been poorly understood. Here, we review recent work that is beginning to identify factors responsible for intestinal conditioning of dendritic-cell function and the subsequent decision between tolerance and immunity in the intestine.     

肠道菌群在机体免疫调节功能中的作用

肠道菌群被称为是人体的一个重要"器官",具有数量庞大、种类繁多等特点,对人体具有重要的生理与病理意义。肠道菌群对机体免疫功能的影响日益受到广泛关注。本文主要就肠道菌群对肠道形态及功能、肠道黏膜免疫系统以及肠道外免疫系统三个方面的影响进行综述。     

Homeostasis of peripheral immune effectors

In this paper, we use both mathematical modeling and simulation to explore homeostasis of peripheral immune system effector cells, particularly alveolar macrophages. Our interest is in the distributed control mechanisms that allow such a population to maintain itself. We introduce a multi-purpose simulator designed to study individual cell responses to local molecular signals and their effects on population dynamics. We use the simulator to develop a model of growth factor regulation of macrophage proliferation and survival. We examine the effects of this form of regulation in the context of two competing hypotheses regarding the source of new alveolar macrophages. In one model, local cells divide to replenish the population; in the other, only cells migrating from circulation divide. We find that either scenario is plausible, although the influx-driven system is inherently more stable. The proliferation-driven system requires lower cell death and efflux rates than the influx-driven system.     

细菌耐药影响肠道菌群及其宿主免疫调控

抗生素在养殖业、医疗业及制药业的广泛应用导致环境中的细菌耐药性日益严重,环境中的抗生素及耐药细菌一旦进入人体肠道,将破坏肠道菌群稳态,对人体健康造成威胁,而残存于饮食中的环境污染物则加剧了细菌耐药造成的人体健康影响。文中在总结大量文献的基础上,阐述了细菌耐药对人体和动物肠道菌群的影响机制及其相关的机体免疫调控,以环境中影响人体肠道菌群获得耐药性的来源作为切入点,阐述抗生素和耐药细菌进入人体肠道后对人体肠道菌群结构和耐药基因组成的影响,以及与人体免疫和免疫调节相关疾病之间的相关机制,并对今后的研究方向进行了展望。     

益生菌对克罗恩病患者肠道屏障功能和免疫调节的影响

研究益生菌对克罗恩病患者肠道屏障功能和免疫调节的影响,为该类患者的治疗提供参考。

选择2018年1月至2020年6月我院收治的94例克罗恩病患者进行前瞻性随机对照研究,根据住院尾号单双数随机分为单号的对照组（n = 45）和双号的益生菌组（n = 49）。对照组患者给予柳氮磺胺吡啶联合安慰剂治疗,益生菌组患者给予柳氮磺胺吡啶联合双歧杆菌三联活菌片治疗。治疗前及治疗后2个月时,分别检测患者粪便中肠道菌群数量,简化克罗恩病活动指数（CDAI）,血沉（ERS）,血清中超敏C反应蛋白（hs-CRP）、二胺氧化酶、D-乳酸、干扰素-γ（IFN-γ）、白介素（IL）-4、IL-10、IL-17的水平以及外周血中Th1、Th2、Th17、Treg细胞的数目。随访2组患者预后不良终点事件的累积发生率。

治疗后2个月,益生菌组患者粪便中拟杆菌、肠杆菌、肠球菌的数量,简化CDAI、ERS水平,血清中hs-CRP、二胺氧化酶、D-乳酸、IFN-γ、IL-17水平,外周血中Th1、Th17的数量均低于对照组;而粪便中双歧杆菌、乳杆菌数量,血清中IL-4、IL-10水平,外周血中Th2、Treg的数量均高于对照组（均P＜0.05）。随访过程中,益生菌组患者预后不良终点事件的累积发生率低于对照组（P＜0.05）。

益生菌能够改善克罗恩病患者病情及肠道屏障功能,调节免疫应答,同时也对预后具有改善作用。

     

Systemic regulation of intestinal iron absorption

The intestinal absorption of the essential trace element iron and its mobilization from storage sites in the body are controlled by systemic signals that reflect tissue iron requirements. Recent advances have indicated that the liver-derived peptide hepcidin plays a central role in this process by repressing iron release from intestinal enterocytes, macrophages and other body cells. When iron requirements are increased, hepcidin levels decline and more iron enters the plasma. It has been proposed that the level of circulating diferric transferrin, which reflects tissue iron levels, acts as a signal to alter hepcidin expression. In the liver, the proteins HFE, transferrin receptor 2 and hemojuvelin may be involved in mediating this signal as disruption of each of these molecules decreases hepcidin expression. Patients carrying mutations in these molecules or in hepcidin itself develop systemic iron loading (or hemochromatosis) due to their inability to down regulate iron absorption. Hepcidin is also responsible for the decreased plasma iron or hypoferremia that accompanies inflammation and various chronic diseases as its expression is stimulated by pro-inflammatory cytokines such as interleukin 6. The mechanisms underlying the regulation of hepcidin expression and how it acts on cells to control iron release are key areas of ongoing research.     

Ligand-receptor relationships in immune regulation

The relationship between ligand, idiotype-bearing ligand-binding T suppressor cells (Ts), and antiidiotypic Ts is discussed. The suppressor pathway involves the activation by ligand of first-order idiotypic Ts (Ts1) which elaborate idiotype-bearing T suppressor factors (TsF). TsF readily induced second-order antiidiotypic TS2 cells. The genetic restrictions imposed on the immune system once perturbed by antigen are evaluated.     

Genetic regulation of testosterone-induced immune suppression

Genes in the major histocompatibility complex (H-2) of the mouse control several immune functions as well as various facets of testosterone (Te) physiology. In order to study the genetic control of Te-induced immune suppression, complete Freund's adjuvant (CFA; containing Mycobacteria tuberculosis) was administered parenterally to several mouse strains differing at the H-2 complex which were either sham- or Te-treated. The specific lymphocyte proliferative response to purified protein derivative (PPD) was measured in draining lymph node cells. The response to PPD in strains bearing H-2b (B6 and B10) but not H-2d (B10.D2 and DBA/2) or H-2k (B10.BR and AKR) haplotypes was markedly lower in Te-implanted compared to sham-implanted controls. This result suggests that the ability of Te to dampen the immune response to PPD is regulated by H-2-linked gene(s).     

Role of exosomes in immune regulation

Exosomes are small vesicles originating from late endosomes, 30-100 nm in diameter with typical cup-shape morphology. They are reported to bear high levels of a narrow spectrum of molecules involved in immune response and signal transduction. Apart from removing obsolete membrane proteins, some surprising biological functions of exosomes were unveiled recently and their applications in immunotherapy of tumors are currently intensively investigated. Dendritic cell- (DC) and tumor-derived exosomes have considerable anti-tumor effects in experimental studies and several clinical trials. Despite their potential applications in eliciting a "positive" immune response, exosomes might induce some "unwanted" immune responses, such as immune tolerance and immune evasion. Therefore further investigations about the physiological functions of exosomes and the optimal way of exosome application in tumor immunotherapy are necessary. This review presents recent developments in the field of exosome research and focuses on its applications to tumor immunotherapy.     

益生菌调节肠上皮细胞免疫反应的研究进展

肠道不仅是消化吸收的场所,而且是人体重要的免疫器官。益生菌通常被认为是胃肠道共生菌,摄入适量时,可对宿主产生益处。现就益生菌可调节肠道屏障功能,并通过固有免疫和适应性免疫反应来调节肠上皮细胞介导的免疫反应的相关研究作一综述,为开发新型益生菌制剂,抑制肠道病原菌提供了研究思路。