潘氏细胞研究进展

潘氏细胞是位于小肠腺底部的浆液性腺上皮细胞,其主要特征是细胞顶部有大量粗大的嗜酸性分泌颗粒,内含防御素、溶茵酶、sIgA等多种抗菌物质.表达于潘氏细胞的NOD2、Toll样受体9、肝癌-肠-胰腺/胰腺炎相关蛋白、RegⅢy、肿瘤坏死因子α、粒细胞-巨噬细胞集落刺激因子、白介素-17等也是免疫与炎症反应的重要成分.金属硫蛋白、富半胱氨酸肠蛋白、潘氏细胞锌结合蛋白等金属结合蛋白均分布于潘氏细胞,提示潘氏细胞参与金属代谢.潘氏细胞是构成肠黏膜屏障的重要细胞成分.NOD2单核苷酸多态性与克罗恩病有关.潘氏细胞化生常发生于胃、大肠的炎症与肿瘤病变,其病理意义有待于进一步研究.     

窖蛋白-1、基质金属蛋白酶-2与乳腺肿瘤的侵袭和转移

窖蛋白(caveolin)是分子量为21～24 kD的整合膜蛋白,是胞膜窖(caveolae)的标志性结构分子,其家族成员窖蛋白-1(caveolin-1,Cav-1)参与细胞内许多重要的生命活动.近来研究发现,窖蛋白-1与乳腺上皮细胞转化及乳腺癌的发生密切相关.基质金属蛋白酶(matrix metalloproteinases,MMPs)是基质降解代谢的主要酶类,几乎能降解细胞外基质和基底膜的所有成分,其家族成员明胶酶A(MMP-2)在乳腺癌的浸润和转移过程中起重要作用.新近发现,窖蛋白-1与基质金属蛋白酶-2在胞膜窖中共定位,窖蛋白-1通过抑制基质金属蛋白酶-2的激活来抑制乳腺癌的侵袭和转移,起到肿瘤抑制因子的作用.本文对窖蛋白-1与基质金属蛋白酶-2各自在乳腺肿瘤侵袭转移中的作用及两者关系的研究进行综述.     

潘氏细胞及其防御素的研究进展

潘氏细胞防御素(Paneth cell defensin,PCD)在维持动物消化道内稳态、参与消化道固有免疫方面发挥重要作用,潘氏细胞的变化与肠道功能异常有密切关系。研究发现潘氏细胞α-防御素表达紊乱是炎症性肠病的关键发病因素之一。本文综述潘氏细胞的分布和形态、生物学特点、潘氏细胞防御素的生物合成过程及其功能。     

关于IL-10抗炎机制的研究

IL-10属于细胞因子中的干扰素家族,研究发现内源性和外源性的IL-10均能在转录水平上强烈抑制IL-1、IL-6、IL-8肿瘤坏死因子-α(TNF-α)、GM-CSF、G-CSF的合成.近十年来,研究认为IL-10主要是通过抑制IKK的激活或NF-κB的DNA结合能力,从而抑制NF-κB启动相关前炎症因子基因的转录.但同时,国外也报道过IL-10抑制炎症细胞因子如TNF-α的合成可能与NF-κB无关,而与如AP-1,细胞因子信号抑制子-3(SOCS-3)等其他蛋白相关.另一方面,最近随着对NOD家族成员NOD2及其同源异构体的深入研究,有证据表明IL-10对NF-κB的作用可能不仅仅局限在IKK(IκB的激酶)及其下游的水平上,而在上游也会造成影响.     

c-FLIP的分子调节机制

细胞型含死亡域的Fas结合蛋白样白介素-1β转换酶抑制蛋白(cellular FADD-like interleukin-1βconverting enzyme inhibitory protein,c-FLIP)是一类含有死亡效应结构域(the death effector domain,DED)的天然存在的胱天蛋白酶(caspase)抑制蛋白,广泛存在于各种生物物种中,其过量表达能抑制Fas和肿瘤坏死因子相关促凋亡配体(TRAIL)等死亡受体介导的细胞凋亡。目前认为c-FLIP与炎症、肿瘤及自身免疫性疾病的发生发展密切相关。对其分子调节机制的深入研究将有助于深化对这些疾病的认识,并为临床治疗这些疾病提供新的方法和思路。     

细胞外基质与基质金属蛋白酶

细胞外基质（ECM）是存在于细胞之间的动态网状结构,由胶原、蛋白聚糖及糖蛋白等大分子物质组成.这些大分子物质可与细胞表面上的特异性受体结合,通过受体与细胞骨架结构直接发生联系或触发细胞内的一系列信号传导而引起不同的基因表达,从而导致细胞的生长和分化.作为降解ECM成分最重要的酶-基质金属蛋白酶（MMPs）及其组织抑制因子(TIMPs)在这一过程中起着非常重要的作用.MMPs是一类依赖金属离子锌并以ECM成分为水解底物的蛋白水解酶.其在转录水平的表达受到生长因子、细胞因子及激素等因素的严格调控,在蛋白质水平其活性也受到其激活剂和抑制剂的调节. MMPs通过对ECM成分的水解来影响其降解与重组的动态平衡而参与多种细胞的生理和病理过程.     

血管内皮祖细胞与炎性因子相关性的研究进展

内皮祖细胞(EPCs)是一种能直接分化为血管内皮细胞的前体细胞,不仅参与胚胎期的血管发生,还存在于骨髓、外周血和脐血中,在成体血管新生和受损内膜的再内皮化中发挥重要作用.然而,血管发生和炎症反应是两个密切联系的过程,血管损伤通常伴有局部促炎症介质的释放.多种炎症介质通过不同信号通路影响内皮祖细胞的数量和功能,从而影响损伤血管的修复和再生,参与炎症反应的发生和发展.本文结合近年来的研究进展,就EPCs与炎性相关因子如C-反应蛋白、肿瘤坏死因子-α、白细胞介素-1β、血管生成素、基质细胞衍生因子-1等的关系作一综述.     

NOD:一类新的固有免疫模式识别受体

哺乳动物主要通过Toll样受体(TLR)识别微生物。最近,发现一个新的蛋白质家族,核苷酸结合寡聚化结构域(NOD),参与胞内微生物的模式识别。NOD是一类位于胞质有典型的LRR-NBS结构的蛋白质家族,可以识别细菌细胞壁成分——细菌肽聚糖(peptidoglycan,PGN),活化NF-κB,参与固有免疫应答并诱导炎症反应和细胞凋亡。其中最有代表性的是NOD1和NOD2。最近的研究发现,NOD1和NOD2能识别细菌特殊结构。对该家族的研究将有助于防治胞内病原体感染、探索炎症性疾病的发病机制和治疗方案。     

NLRP3炎症小体的负向调控机制

NLRP3炎症小体是由NOD样受体(NOD-like receptor, NLR) NLRP3、接头蛋白ASC和胱冬肽酶-1(Caspase-1)所形成的多聚蛋白复合体,能够感受来自病原微生物的病原相关分子模式(pathogen-associated molecular patterns, PAMPs)和胞内自身危险信号-危险相关分子模式(danger-associated molecular patterns, DAMPs),促进细胞因子IL-1β和IL-18的成熟和分泌、引起细胞焦亡,从而在多种生理、病理过程中发挥重要作用. NLRP3炎症小体是目前研究最深入的炎症小体,其表达水平和活化强度与多种疾病的发生、发展密切相关,如感染性疾病、痛风、Ⅱ型糖尿病、动脉粥样硬化、阿尔兹海默症及癌症等.因此,阐明NLRP3炎症小体活化的调控机制,对于揭示这些疾病发生、发展的机理,寻找免疫调节治疗的新途径具有重要意义.本文详细介绍了NLRP3炎症小体的负向调控机制.     

泛素化在TRAF2介导的NF-κB信号通路中的作用

NF-κB（核因子κ增强子结合蛋白）是核转录因子家族成员,具有调节免疫、炎症和细胞存活的功能.它可被TRAF2（tumor necrosis factor receptor associated factor 2,肿瘤坏死因子受体相关因子2）等相关因子活化.TRAF2包含了N-端的环指结构域和C-端的高度保守结构域.它通过与肿瘤坏死因子受体超家族成员相互作用,介导了下游信号通路.而TRAF2的泛素化在过程中是关键的,鞘磷脂作为TRAF2的泛素化连接酶辅助因子,在TRAF2介导的NF-κB信号通路中发挥重要作用.     

The role of Paneth cells and their antimicrobial peptides in innate host defense

The intestinal epithelium is the largest surface area that is exposed to various pathogens in the environment, however, in contrast to the colon the number of bacteria that colonize the small intestine is extremely low. Paneth cells, one of four major epithelial cell lineages in the small intestine, reside at the base of the crypts and have apically oriented secretory granules. These granules contain high levels of antimicrobial peptides that belong to the alpha-defensin family. Paneth cells secrete these microbicidal granules that contain alpha-defensins when exposed ex vivo to bacteria or their antigens, and recent evidence reveals that antimicrobial peptides, particularly alpha-defensins, that are present in Paneth cells contribute to intestinal innate host defense.     

Effects of Trichinella spiralis infection on intestinal pathology in mice lacking interleukin-4 (IL-4) or intestinal trefoil factor (ITF/TFF3)

The nematode Trichinella spiralis induces pathological changes in the small intestine of the host, which are known to be controlled by immune and inflammatory mediators. The detail of this control has still to be completely understood. Mice deficient in interleukin 4 (IL-4) or in intestinal trefoil factor/trefoil family factor 3 (ITF/TFF3) were infected with T. spiralis and the resultant changes in the intestinal mucosa followed by quantifying numbers of mucosal mast cells, goblet cells, Paneth cells and by monitoring structural changes in villus length and crypt depth. Mice lacking IL-4 were unable to mount a normal protective response to infection, such that worm survival was increased. These mice failed to mount a mucosal mast cell response, but did make goblet cell and Paneth cell responses comparable to normal controls. Mice lacking ITF/TFF3 similarly made normal levels of goblet cell and Paneth cell responses. They also underwent profound changes in mucosal architecture, with marked villus atrophy and crypt hyperplasia. These results are discussed in relation to known patterns of T cell and cytokine control of protective immunity to T. spiralis. They suggest that increased numbers of goblet cell and Paneth cell are not, by themselves, required for protective immunity. ITF/TFF3 appears not to influence cellular responses and does not alter parasite-induced pathological changes in the small intestine.     

Cloning of intestinal phospholipase A2 from intestinal epithelial RNA by differential display PCR

Differential display polymerase chain reaction (DD-PCR) is a powerful technique for comparing gene expression between cell types, or between stages of development or differentiation. Differentially expressed genes may be cloned and analysed further. Here we extend the use of DD-PCR to analyse differences in gene expression between two complex epithelia: that of the small intestine and of the large intestine. The aim of this study was to identify genes expressed preferentially in Paneth cells. Paneth cells are secretory epithelial cells putatively involved in host defense and regulation of crypt cell proliferation and are found at the base of the small intestinal crypts adjacent to the stem cell zone. Of 34 clones that were analysed, partial sequencing identified two clones related to known Paneth cell products: a homologue of secretory phospholipase A2 (clone B1) and a homologue of a neutrophil defensin (clone C5). B1 was strongly expressed in Paneth cells, as demonstrated by in-situ hybridization. B1 was also expressed at a lower level in the large intestinal epithelium. A full length B1 cDNA clone was isolated and sequenced, and shown to be highly homologous to type II secretory phospholipase A2 genes, and almost identical to the enhancing factor gene and the putative gene for the MOM-1 locus. B1 expression is limited to the intestinal tract, and we propose that it be designated intestinal phospholipase A2, or i -PLA2. The method we describe is well suited to the rapid identification of genes expressed exclusively or predominantly in Paneth cells.     

Identification of xanthine dehydrogenase/xanthine oxidase as a rat Paneth cell zinc-binding protein

Paneth cells are zinc-containing cells localized in small intestinal crypts, but their function has not been fully elucidated. Previously, we showed that an intravenous injection of diphenylthiocarbazone (dithizone), a zinc chelator, induced selective killing of Paneth cells, and purified a zinc-binding protein in Paneth cells. In the present study, we further characterized one of these proteins, named zinc-binding protein of Paneth cells (ZBPP)-1. Partial amino acid sequences of ZBPP-1 showed identity with rat xanthine dehydrogenase (XD)/xanthine oxidase (XO). Anti-rat XD antibody (Ab) recognized ZBPP-1, and conversely anti ZBPP-1 Ab recognized 85 kDa fragment of rat XD in Western blotting. Messenger RNA and protein levels of XD were consistent with our previous data on the fluctuation of Paneth cell population after dithizone injection. Thus, ZBPP-1 is an 85 kDa fragment of XD/XO in Paneth cells. XD/XO in Paneth cells may play important roles in intestinal function.     

Lipopolysaccharide-binding protein: localization in secretory granules of Paneth cells in the mouse small intestine

Lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase protein involved in the host’s response to endotoxin and mainly synthesized and secreted to the blood by the liver. But in addition, LBP is also made by extrahepatic cells, including the enterocyte-like cell line Caco-2. To study in closer detail the synthesis and storage of LBP in the intestinal mucosal epithelium, we performed an immunolocalization of LBP in mouse small intestine. By immunofluorescence microscopy, an antibody recognizing the 58–60 kDa protein of LBP distinctly labeled a small population of cells located deep into the crypts. This cell population was also positive for lysozyme and α-defensin 4, identifying Paneth cells as the main intestinal LBP-producing cells. By immunogold electron microscopy, intense labeling was observed in the secretory granules of these cells. We conclude that Paneth cells express LBP together with other proteins acting in the innate immune response of the gut, such as lysozyme, defensins and intelectin.     

Ultrastructural localization of osteopontin immunoreactivity in phagolys osomes and secretory granules of cells in human intestine

A post-embedding ultrastructural immunogold method was used to detect osteopontin in human intestinal biopsies with special emphasis on secretory and phagocytic organelles. Osteopontin immunoreactivity was localized to phagolysosomes of macrophages, fibroblasts, absorptive epithelial cells of the small intestine and Paneth cells. The mucigen secretory granules and Golgi structures of mucous epithelial cells of the small intestinal epithelium contained osteopontin, but secretory granules of numerous other cells, including Paneth cells, did not. Extracellular and phagocytosed Tropheryma whippelii within macrophage phagolysosomes also bound osteopontin. These localizations are supportive of a role for osteopontin in phagocytic and some secretory cell functions in human intestine     

Ultrastructural localization of osteopontin immunoreactivity in phagolys osomes and secretory granules of cells in human intestine

A post-embedding ultrastructural immunogold method was used to detect osteopontin in human intestinal biopsies with special emphasis on secretory and phagocytic organelles. Osteopontin immunoreactivity was localized to phagolysosomes of macrophages, fibroblasts, absorptive epithelial cells of the small intestine and Paneth cells. The mucigen secretory granules and Golgi structures of mucous epithelial cells of the small intestinal epithelium contained osteopontin, but secretory granules of numerous other cells, including Paneth cells, did not. Extracellular and phagocytosed Tropheryma whippelii within macrophage phagolysosomes also bound osteopontin. These localizations are supportive of a role for osteopontin in phagocytic and some secretory cell functions in human intestine This revised version was published online in November 2006 with corrections to the Cover Date.     

Selenoprotein S is a marker but not a regulator of endoplasmic reticulum stress in intestinal epithelial cells

Selenoproteins are candidate mediators of selenium-dependent protection against tumorigenesis and inflammation in the gut. Expression and roles of only a limited number of intestinal selenoproteins have been described so far. Selenoprotein S (SelS) has been linked to various inflammatory diseases and is suggested to be involved in endoplasmic reticulum (ER) homeostasis regulation and antioxidative protection in a cell-type-dependent manner, but its protein expression, regulation, and function in the gut are not known. We here analyzed the expression and localization of SelS in the healthy and inflamed gut and studied its regulation and function in intestinal epithelial cell lines. SelS was expressed in the intestinal epithelium of the small and large intestine and colocalized with markers of Paneth cells and macrophages. It was upregulated in inflamed ileal tissue from Crohn's disease patients and in two models of experimental colitis in mice. We detected SelS in colorectal cell lines, where it colocalized with the ER marker calnexin. SelS protein expression was unaffected by enterocytic differentiation but increased in response to selenium supplementation and after treatment with the ER stress inducer tunicamycin. On the other hand, depletion of SelS in LS174T, HT29, and Caco-2 cells by RNA interference did not cause or modulate ER stress and had no effect on hydrogen peroxide-induced cell death. In summary, we introduce SelS as a novel marker of Paneth cells and intestinal ER stress. Although it is upregulated in Crohn's disease, its role in disease etiology remains to be established.     

NOD2 mutation and mice: no Crohn's disease but many lessons to learn

Many patients with ileal Crohn's disease, a chronic intestinal inflammation, carry mutations in the gene encoding NOD2 (CARD15), but the mechanistic details of how this mutation leads to disease are not fully understood. NOD2 is expressed in antigen-presenting cells and Paneth cells, which are secretory epithelial cells of the small intestine. Two complementary studies using genetically engineered murine models help to explain the association of NOD2 malfunction and mucosal disease. One study observes a dysregulation of proinflammatory responses, suggesting that the most common NOD2 mutation in humans results in a gain of function. The other study determined that NOD2-null mutations impair the Paneth-cell antimicrobial response, which is consistent with recent findings in humans. Together, these studies fuel optimism that new therapeutic directions might emerge to better treat this severe mucosal disease.