儿童重症手足口病肠道菌群和肠道黏膜通透性的研究进展

手足口病是由肠道病毒引起的儿童常见的传染病,有研究显示肠道病毒进人消化道后在肠黏膜内复制繁殖并持续释放到血液而发病,肠道黏膜是病毒人侵和增殖的主要场所。肠道菌群能防御感染和增强肠道屏障功能,肠道屏障功能在防御外源性和内源性感染方面发挥重要作用,同时在维持肠道免疫稳定和平衡方面也有重要的作用。益生菌是指数量适当时对宿主健康有利的活微生物,有研究报道益生菌在辅助治疗手足口病上是有效的。开展这方面的研究,对于探索手足口病的发病机制和益生菌防治手足口病有十分重要的意义。     

Phlorizin increases the permeability of intestinal mucosal membrane to sodium

We reported previously that when jejunal transmural glucose transport was inhibited by phlorizin the ratio of Na:glucose transport increased from 2.0:1 (in controls) to 3.3:1. To elucidate the mechanism of this increased ratio of Na:glucose transport, in the present study we have investigated the effect of phlorizin on Na uptake by brush border membrane vesicles and by everted sacs of hamster jejunum. In experiments on membrane vesicles the following observations were made. The time course of Na uptake showed that the control vesicles were in complete equilibrium with a Na-containing (100 mM) medium between 30 and 90 min incubation. In these periods of incubation, the vesicles incubated with phlorizin presumably also equilibrated with the medium, but lost their intravesicular Na during Millipore filtration and washing, and consequently the residual Na content was lower than that of controls. This effect of phlorizin was concentration dependent, and appeared to be unrelated to Na-coupled glucose transport, because it was also observed in the absence of glucose. This loss of Na during Millipore filtration and washing was also observed (i) when vesicles were equilibrated in a Na-containing solution in the absence of phlorizin and then exposed to a similar solution containing phlorizin, or (ii) when vesicles were equilibrated in a Na-containing solution in the presence of phlorizin and then washed repeatedly following Millipore filtration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise training prevents ecto-nucleotidases alterations in platelets of hypertensive rats

Mechano-growth factor (MGF) has emerged as an important mechanosensitive player in bone repair, but understanding of MGF function is hampered by the fact that MGF receptor and the underlying pathways remain unknown. In this study, fluorescein isothiocyanate (FITC)-labeled MGF-Ct24E (FITC-MGF) was used to determine the subcellular localization of MGF receptor in osteoblasts. After the primary osteoblasts were exposed to stretch with the strain at 10?%, and/or loaded with 50?ng/ml exogenous MGF-Ct24E, cells were incubated with the different concentrations of FITC-MGF (0.01, 0.1, and 1?mg/ml) followed by flow cytometry and laser scanning confocal microscope analysis. Our results showed that the fluorescence intensity and cell population internalizing FITC-MGF increased with the concentration of FITC-MGF. And all the cells were labeled with fluorescence at 1?mg/ml. Notably, FITC-MGF had nuclear localization when osteoblasts were exposed to stretch and/or 50?ng/ml MGF-Ct24E added, compared to the evident cytoplasmic localization in the static culture group. The nuclear localization of FITC-MGF in response to mechanical loading was found to associate with high expression of proliferating cell nuclear antigen, suggesting MGF and its receptor could serve as potential messengers that replay information in nuclei to control cell proliferation.     

Enhanced zinc consumption prevents cadmium-induced alterations in lipid metabolism in male rats

It has been investigated, based on a rat model of human exposure to cadmium (Cd), whether zinc (Zn) supplementation may prevent Cd-induced alterations in lipid metabolism. For this purpose, the concentrations of free fatty acids (FFA), phospholipids (PL), triglycerides (TG), total cholesterol (TCh), and high and low density lipoprotein cholesterol (HDL and LDL, respectively) as well as the concentrations of chosen indices of lipid peroxidation such as lipid peroxides (LPO), F₂-isoprostane (F₂-IsoP) and oxidized LDL (oxLDL) were estimated in the serum of male Wistar rats administered Cd (5 or 50 mg/l) or/and Zn (30 or 60 mg/l) in drinking water for 6 months. The exposure to 5 and 50 mg Cd/l resulted in marked alterations in the lipid status reflected in increased concentrations of FFA, TCh, LDL, LPO, F₂-IsoP and oxLDL, and decreased concentrations of PL and HDL in the serum. The concentrations of LDL, LPO, F₂-IsoP and oxLDL were more markedly enhanced at the higher Cd dosage. The supplementation with Zn during the exposure to 5 and 50 mg Cd/l entirely prevented all the Cd-induced changes in the serum concentrations of the estimated lipid compounds and indices of lipid peroxidation, except for the F₂-IsoP for which Zn provided only partial protection. Based on the results it can be concluded that Zn supplementation during exposure to Cd may have a protective effect on lipid metabolism consisting in its ability to prevent hyperlipidemia, including especially hypercholesterolemia, and to protect from lipid peroxidation. The findings seem to suggest that enhanced dietary Zn intake during Cd exposure, via preventing alterations in the body status of lipids may, at least partly, protect against some effects of Cd toxicity, including oxidative damage to the cellular membranes and atherogenic action. The paper is the first report suggesting protective impact of Zn against proatherogenic Cd action on experimental model of chronic moderate and relatively high human exposure to this toxic metal.     

Suppression of intestinal mucosal apoptosis by ghrelin in fasting rats

Ghrelin is mainly produced in the stomach and has several physiologic functions. The aim of this study was to investigate whether ghrelin regulates apoptosis in the small intestinal mucosa of fasting rats. Intestinal mucosal apoptosis was evaluated as the percentage of fragmented DNA, villus height, and terminal deoxynucleotidyl transferase-mediated dUDP-biotin nick end-labeling (TUNEL) staining and by Western blot analysis of caspase-3 in 48-hr fasting rats. Crypt cell proliferation was evaluated by counting the number of 5-bromo-2-deoxyuridine (BrdU) positive cells. Ghrelin was administered intraperitoneally at dosages of 2.5, 25, and 250 microg/kg per 48 hrs by continuous infusion via an Alzet micro-osmotic pump or injections at 12-hr intervals. Ghrelin was also infused in rats that underwent truncal vagotomy. The lowest dosage of ghrelin (2.5 microg/kg per 48 hrs) was administered into the third cerebroventricle. Ghrelin treatment attenuated the percentage of fragmented DNA in the small intestinal mucosa in 48-hr fasting rats in a dose-dependent manner. Continuous infusion of ghrelin and injections of ghrelin at 12-hr intervals suppressed intestinal apoptosis almost equally. This effect on apoptosis was not attenuated by truncal vagotomy. Cerebroventricular infusion of ghrelin also attenuated intestinal apoptosis. The antiapoptotic effect of ghrelin was confirmed by decreased TUNEL staining, recovery of the villus height, and decreased expression of caspase-3. BrdU uptake indicated that ghrelin enhanced cell proliferation in the intestinal crypt. Taken together, these data indicate that ghrelin enhanced intestinal growth with the suppression of small intestinal mucosal apoptosis in 48-hr fasting rats, suggesting that ghrelin controls intestinal function through the regulation of intestinal apoptosis.     

Effect of orally-administered epidermal growth factor on intestinal iron absorption and mucosal permeability

A progressive increase in intestinal 59Fe3+ absorption was observed on oral feeding of mice with physiological doses of EGF/UGO. Maximal changes were apparent after 3d and appeared to be dose-dependent. In addition to a small increase in intestinal cell proliferation, as reflected by increased ornithine decarboxylase activity, EGF/UGO-feeding increased mucosal permeability (evaluated with [51Cr]-EDTA): the latter could account for the increase in iron absorption. Sialoadenectomy, to remove the major source of endogenous EGF/UGO, had no appreciable effect on the intestinal absorption of iron.     

Neutrophil depletion retards endometrial repair in a mouse model

The contribution of the high abundance of inflammatory cells present in the human endometrium prior to and during menstruation is unknown with respect to endometrial repair and/or menstruation. In this study, the presence and localisation of markers for key inflammatory cells have been examined in a mouse model of endometrial breakdown and repair and the functional contribution of neutrophils has been determined. In the model, decidualisation is artificially induced and progesterone support withdrawn; the endometrial tissue progressively breaks down by 24 h after progesterone withdrawal and, by 48 h, has usually undergone complete repair. Neutrophils have been identified in low abundance in decidual tissue, rise in number during breakdown and are most abundant during early repair. Macrophages are barely detectable during breakdown or repair in this model, whereas uterine natural killer cells are found only in intact decidua. The functional contribution of neutrophils to endometrial breakdown and repair has been assessed via neutrophil depletion by using the antibody RB6-8C5. This antibody significantly depletes neutrophils from the circulation and tissue, affects endometrial breakdown and markedly delays endometrial repair. This study has therefore demonstrated that neutrophils are the most abundant leucocyte in this model and that they play an important functional role in the processes of endometrial breakdown and repair. This work was funded by the National Health and Medical Research Council of Australia (#143798, #241000) and by an Australian Postgraduate Scholarship to T.K.     

双歧杆菌三联活菌散对儿童轮状病毒性肠炎患者肠道菌群及肠黏膜通透性的影响

目的 观察双歧杆菌三联活菌散对儿童轮状病毒性肠炎（RVE）患者肠道菌群和肠黏膜通透性的影响。方法 选择2016年1月至2017年8月于丽水市中心医院儿科门诊治疗的RVE患儿94例,随机分为观察组和对照组各47例。两组患儿均予饮食调整、补液及纠正电解质紊乱和酸碱失衡等治疗。观察组患儿加用双歧杆菌三联活菌散1.0 g/次,3次/d,温水冲服。观察两组患儿治疗前后肠道菌群（双歧杆菌、乳杆菌和大肠埃希菌）数量和肠黏膜通透性指标[内毒素（ETX）和D-乳酸]的变化,并比较其临床疗效。结果 治疗72 h后,观察组患儿双歧杆菌和乳杆菌数量明显上升,大肠埃希菌数量明显下降（P0.05）。治疗后观察组患儿双歧杆菌、乳杆菌数量较对照组更高,大肠埃希菌数量较对照组更低（P<0.05）。两组患儿治疗后血清ETX和D-乳酸水平均明显下降（P<0.05）,且观察组下降幅度更大（P<0.05）;同时观察组患儿总有效率高于对照组（χ2=4.11,P<0.05）。结论 双歧杆菌三联活菌散治疗儿童RVE的疗效确切,其作用机制可能与其能增加双歧杆菌和乳杆菌等有益菌的数量,减少大肠埃希菌等致病菌的数量,改善患儿肠道微生态状况;并与其能降低肠黏膜通透性和减少肠液的分泌渗出相关。     

Physical exercise prevents alterations in purinergic system and oxidative status in lipopolysaccharide-induced sepsis in rats

Sepsis is a generalized infection that involves alterations in inflammatory parameters, oxidant status, and purinergic signaling in many tissues. Physical exercise has emerged as a tool to prevent this disease because of its anti-inflammatory and antioxidant properties. Thus, in this study, we investigated the effects of physical exercise on preventing alterations in purinergic system components, oxidative stress, and inflammatory parameters in lipopolysaccharide (LPS)-induced sepsis in rats. Male Wistar rats were divided into four groups: control, exercise (EX), LPS, and EX+LPS. The resisted physical exercise was performed for 12 weeks on a ladder with 1 m height. After 72 hours of the last exercise session, the animals received 2.5 mg/kg of LPS for induction of sepsis, and after 24 hours, lungs and blood samples were collected for analysis. The results showed that the exercise protocol used was able to prevent, in septic animals: (1) the increase in body temperature; (2) the increase of lipid peroxidation and reactive species levels in the lung, (3) the increase in adenosine triphosphate levels in serum; (4) the change in the activity of the enzymes ectonucleotidases in lymphocytes, partially; (5) the change in the density of purinergic enzymes and receptors in the lung, and (6) the increase of IL-6 and IL-1β gene expression. Our results revealed the involvement of purinergic signaling and oxidative damage in the mechanisms by which exercise prevents sepsis aggravations. Therefore, the regular practice of physical exercise is encouraged as a better way to prepare the body against sepsis complications.     

A time course study of water permeability and morphological alterations induced by mucosal hyperosmolarity in frog urinary bladder

Summary The role of the tight junction in the hydrosmotic response of the frog urinary bladder has been analysed by comparative kinetic studies and freeze etching examination. The comparison of the time course of the variations in transepithelial water net flux and of the alterations of tight junction ultrastructure in bladders exposed to mucosal hyperosmolar solutions shows that blisters are present in the tight junction before any increase in transepithelial water net flux. This indicates that the two phenomena are dissociated.In the same experimental conditions, freeze etching examination shows the presence in the tight junction of large areas of smooth and apparently stretched membrane where the typical network structure has disappeared. These alterations are reduced by further treatment with oxytocin and are probably not involved in the physiological hydrosomotic response.This work was supported in part by a grant from the Medical Research Council of Canada (J.H.).     

Microscopical determination of the filtration permeability of the mucosal surface of the goldfish intestinal epithelium

Summary The rate of shrinkage of the mucosal folds of goldfish intestine in response to mucosal hypertonicity was measured by microscopic means. Because of the geometry of the intestinal folds the rate of shrinkage could be directly related to the loss of volume from the fold through the brush border membranes and tight junctions. Experimentally a wide range of velocities was observed, reflecting the difficulty of rapidly estabilishing a uniform osmotic gradient at the preparation's mucosal surface. The initial velocity of volume loss provided a measure of the filtration permeability (P _f ) of the mucosal surface. From the highest velocities observed the filtration permeability was estimated to be approximately 14×10^–3 cm/sec related to the folded mucosal surface and 65×10^–3 cm/sec related to the straight serosal surface. Consideration of the experimental errors and unstirred layer effects make it probable that the latter value is still an underestimate of the trueP _f . The series barriers of the epithelium cause the total tissueP _f to be less than theP _f of the mucosal surface alone. In addition theP _f measured in the presence of an osmotic gradient may differ substantially from the tissue filtration permeability which exists in the absence of a change in osmolarity.     

Rapid anti-helminthic response of B lymphocytes in the intestinal mucosal tissues of rats

B cell response to Trichinella spiralis (Ts) adult antigen (Ag) was studied in rats 1-20 days postinfection. B cell recoveries from the mesenteric lymph node (MLN), Peyer's patches (PP), thoracic duct lymph (TDL), and the spleen were determined by FACS analysis and Ag-specific antibody-producing cells (Ab-pc) in these tissues were enumerated using the immunoplaque assay. Total B cell numbers increased 2-70 times from day 3 postinfection in the MLN and TDL obtained from MLN-resected rats (MX) and such proliferation was not found in the PP or the spleen. Ab-pc of all isotypes increased from day 3 in the MLN and from day 2 in the MX-TDL. Among all isotypes, IgE- and IgG1-pc showed the strongest response. Immunofluorescence study revealed that these B cells were activated in the non-PP region of the small intestine. These results indicate an early isotype switch to IgG1 and IgE production in Ts-infected small intestine.     

Time-dependent intestinal adaptation and GLP-2 alterations after small bowel resection in rats

Existing data on morphological adaptation after small bowel resection are obtained by potentially biased methods. Using stereological techniques, we examined segments of bowel on days 0, 4, 7, 14, and 28 after 80% jejunoileal resection or sham operation in rats and correlated intestinal growth with plasma levels of glucagon-like peptide-2 (GLP-2). In the jejunum and ileum of the resected rats, the mucosal weight increased by 120 and 115% during the first week, and the weight of muscular layer increased by 134 and 83%, compared with sham-operated controls. The luminal surface area increased by 190% in the jejunum and by 155% in the ileum after 28 days. The GLP-2 level was increased by 130% during the entire study period in the resected rats. Small bowel resection caused a pronounced and persistent transmural growth response in the remaining small bowel, with the most prominent growth occurring in the jejunal part. The significantly elevated GLP-2 level is consistent with an important role of GLP-2 in the adaptive response.     

Protective effect of dexmedetomidine on intestinal mucosal barrier function in rats after cardiopulmonary bypass

Cardiopulmonary bypass can result in damage to the intestines, leading to the occurrence of systemic inflammatory response syndrome. Dexmedetomidine is reported to confer anti-inflammatory properties. Here, the purpose of this study is to investigate the effect of dexmedetomidine on the intestinal mucosa barrier damage in a rat model of cardiopulmonary bypass. It was observed that cardiopulmonary bypass greatly decreased the levels of hemodynamic parameters than SHAM group, whereas dexmedetomidine pretreatment in a cardiopulmonary bypass model rat prevented this reduction. Also, it showed that compared with control animals, cardiopulmonary bypass caused obvious mucosal damage, which was attenuated in dexmedetomidine + cardiopulmonary bypass group. The above findings were in line with that of dexmedetomidine pretreatment, which increased the expression of tight junction proteins, but it decreased the levels of DAO, D-LA, FABP2, and endotoxin. Moreover, the results demonstrated that due to pre-administration of dexmedetomidine, the level of pro-inflammatory factors was decreased, while the level of anti-inflammatory cytokine was increased. Also, it showed that dexmedetomidine suppressed TLR4/JAK2/STAT3 pathway that was activated by cardiopulmonary bypass. Together, these results revealed that dexmedetomidine pretreatment relieves intestinal microcirculation, attenuates intestinal damage, and inhibits the inflammatory response of cardiopulmonary bypass model rats, demonstrating that in CPB-induced damage of intestinal mucosal barrier function, dexmedetomidine pretreatment plays a protective role by inactivating TLR4/JAK2/STAT3-mediated inflammatory pathway.     

参麦注射液对严重烫伤大鼠肠道屏障功能的保护作用

目的:探索参麦注射液对30% Ⅲ°烫伤早期肠道屏障功能的保护作用,为参麦注射液防治肠源性感染提供实验依据。方法:Wistar大鼠60只,随机分为正常对照组、模型对照组,地塞米松5 mg/kg组、参麦注射液5、10、15 mg/kg组,每组10只,使用烫伤仪建立30% Ⅲ°烫伤动物模型,立即腹腔注射相应的药物,每天1次。烫伤72 h后,检测肝脏、脾脏、肠系膜淋巴结细菌移位量、血浆内毒素、二胺氧化酶(DAO)、肿瘤坏死因子-α(TNF-α)及白细胞介素-6(IL-6)水平和肠粘膜分泌型免疫球蛋白A(sIgA)的水平。结果:与正常对照组比较,模型组肝脏、脾脏、肠系膜淋巴结细菌移位量,血浆内毒素、DAO、TNF-α及 IL-6和肠黏膜sIgA水平明显升高(P＜0.01);与模型组比较,地塞米松组和参麦注射液5、10、15 mg/kg组肝脏、脾脏、肠系膜淋巴结细菌移位量,血浆内毒素、DAO、TNF-α及 IL-6和肠黏膜sIgA水平明显降低(P＜0.05或P＜0.01)。结论:参麦注射液可减轻严重烫伤引起的肠粘膜损伤,效果与地塞米松相当,高剂量组效果更好。     

The effects and mechanisms of myeloid differentiation protein 2 on intestinal mucosal permeability in mice with chronic colitis

The present study was designed to investigate the mechanism of myeloid differentiation protein 2 (MD2) on intestinal mucosa destruction in mice with chronic colitis. Briefly, a chronic colitis mouse model was established by the administration of dextran sulfate sodium (DSS) in transgenic mice of MD2 overexpression (Transgenic, MD2-Tg) and C57BL/6 wild-type mice (MD2-WT). In addition, Caco-2 cells were cultured to form a monolayer cell model in vitro. The small interfering RNA was utilized to silence the MD2 gene in Caco-2 cells, and tumor necrosis factor-α (TNF-α) was used to establish the model of intestinal mucosal inflammation. After DSS induction, the intestinal mucosal tissue inflammation was more severe in MD2-Tg mice than MD2-WT. In addition, the intestinal mucosa was severely damaged, the intestinal mucosal permeability was increased, bacterial translocation was obvious, and the expression levels of MD2, MyD88, Toll-like receptor 4 (TLR4), and HMGB1 in mucosal tissues were significantly increased, while the expression levels of tight junction proteins, occludin, and claudin-1 were significantly lower in MD2-Tg mice compared with those in MD2-WT mice. TNF-α could induce inflammatory apoptosis in Caco-2 cell models. After MD2 silencing, the apoptotic level was decreased, the value of transepithelial electrical resistance was increased, the permeability of intestinal mucosa was decreased, the cellular expression levels of MD2, MyD88, TLR4, and HMGB1 were decreased, while the expression levels of tight junction proteins, occludin and claudin-1 were increased. MD2 could aggravate the destruction of intestinal mucosa in chronic colitis through the HMGB1-TLR4-MyD88 pathway.