Abnormal intestinal permeability and microbiota in patients with autoimmune hepatitis

Background: Autoimmune hepatitis (AIH) is a chronic, progressive, and immunologically mediated inflammatory liver disorder. The etiology of AIH still remains unknown. The aim of this study was to investigate the changes in intestinal permeability, bacterial translocation, and intestinal microbiome in patients with AIH and to evaluate the correlations of those changes with the stages of the disease. Methods: 24 patients with autoimmune hepatitis and 8 healthy volunteers were recruited for this study. We assessed (1) the integrity of tight junctions within the gut by immunohistochemical analysis of zona occludens-1 and occludin expression in duodenal biopsy specimens; (2) changes in the enteric microbiome by 16S rDNA quantitative PCR; and (3) the presence of bacterial translocation by the level of lipopolysaccharide (LPS) using ELISA. Results: Increased intestinal permeability, derangement of the microbiome and bacterial translocation occurred in AIH, which correlated with the severity of the disease. Conclusions: Autoimmune hepatitis is associated with leaky gut and intestinal microbiome dysbiosis. The impaired intestinal barrier may play an important role in the pathogenesis of AIH.     

Computer card morphometry of jejunal biopsies in childhood coeliac disease.

The histological changes in 95 jejunal biopsy specimens from children have been analyzed by a new mporphometric technique. The microscope image of the specimen is traced directly onto computer data cards. A simple sketch records accurate quantitative data in a matrix of 840 points, retaining the spatial arrangement of the tissue components. The data are fed via an optical mark data card reader, into a mini-computer. FORTRAN IV programs allow calculation of surface area, villous heights, and component volumes in metric units, and of volume proportions, volume-to-volume ratios, and surface-to-volume ratios. Pictorial and numerical printouts are produced, which are suitable for inclusion in the patient's notes. Jejunal biopsies from 37 controls and 26 untreated coeliac patients were clearly distinguished morphometrically. Sixteen pairs of biopsies from coeliac patients on long-term gluten-free diets before, and 12 weeks after, the reintroduction of dietary gluten significantly reflected the effects of gluten challenge. Comparison of control and abnormal biopsies showed a spatial redistribution of the components, more than a change in their absolute amounts. There was no significant differences in the total epithelial volumes in controls, treated or untreated patients, suggesting that the mucosal lesion in coeliac disease is not a true atrophy.     

Mapping intestinal metaplasia by histochemistry and morphometry

A gastrectomy specimen housing an adenocarcinoma of intestinal type was divided into 60 blocks. Sections were stained with Alcian blue pH 2.5 (to detect foreign mucins). Alcian blue fields were quantitated with a MOP 30 connected to a computer. The mucosa analysed in the 60 sections measured 3788.3 mm2 and that occupied by Alcian blue stained goblet cells 300.9 mm2 (or 7.9% of the total mucosal area). The number of Alcian blue positive fields was significantly larger in the intermediate zone followed by the antral zone, the lowest value was found in the corpus. However, the gastric mucosa with Alcian blue positive cells was larger in the antrum than in the intermediate zone due to the fact that the area of the fields with Alcian blue positive cells was significantly larger in the antrum than in the intermediate zone. The size and number of Alcian blue positive fields were significantly larger along the greater than along the smaller curvature. All measurements were done by a trained technician. The method (using histochemistry, morphometry and skilled technical assistance) will be applied to study the distribution of intestinal metaplasia in gastrectomy specimens from populations with disparate incidences of gastric carcinoma.     

Diamine oxidase plasma activities after treatment with heparin and jejunal morphometry in untreated coeliac disease.

Diamine oxidase plasma concentrations after treatment with heparin were measured and compared with the surface to volume ratio of jejunal biopsy samples assessed by a morphometric technique in patients with untreated and treated coeliac disease and in biopsied controls. As expected, enzyme activity was significantly lower in patients with untreated coeliac disease than in patients on a gluten-free diet and in biopsied controls. No difference was found between treated patients and biopsied controls. There was a significant overall correlation between plasma enzyme activity and surface to volume ratio of jejunal mucosa, although two untreated patients without an overt malabsorption syndrome but with a very low surface to volume ratio had normal enzyme activity. This study shows that in coeliac disease plasma diamine oxidase activity after treatment with heparin does not always mirror the extent of the jejunal lesions, particularly in those patients with minimal or unrelated symptoms who would benefit most from a valid screening test to identify their condition.     

Acute jejunal ileus in intestinal lymphangiectasia

Summary A 26-year-old patient presented with epigastric pain of sudden onset and severe puffy swelling of both legs and forearms. An irregularly shaped nodular filling defect on selective jejunal films, severe hypoproteinemia, low IgG concentration, and lymphopenia were suggestive of primary intestinal lymphangiectasia with protein-losing enteropathy, and the patient was placed on a low-fat diet with medium-chain triglycerides. This initially improved his condition, but some weeks later he developed obstructive ileus of the small intestine. On laparotomy yellowish to whitish deposits were found to be present in some segments of the small intestine and a fist-sized mass 100 cm distal to the duodenojejunal flexure was resected without complications. Histologically, the submucosal lymphatics were dilated, and the jejunal wall showed extensive pseudocystic, intramural submucosal lymph edema with secondary bleeding and tight stenosis of the jejunal lumen. During the 14-month follow-up time after discharge the patient has been asymptomatic and working, on no treatment other than a low-fat diet with medium-chain triglycerides.     

Segmental jejunal lipomatosis--a rare cause of intestinal obstruction

A rare case of a segmental small intestinal (jejunal) lipomatosis is described. A 33-year-old male was admitted with a clinical diagnosis of an acute intestinal obstruction. A plain erect abdominal x-ray showed multiple air-fluid levels. On an exploratory laparotomy, a jejunojejunal intussusception was found secondary to a segmental submucosal lipomatosis. This was treated by a segmental resection and anastomosis, which resulted in a complete cure. Here we present this case with a review of the relevant literature.     

Altered intestinal development after jejunal ligation in fetal sheep

Experimental obstruction of the fetal small intestine resulted in massive hypertrophy of the segment proximal to the site of obstruction. Villus morphology was grossly abnormal. Enterocytes developed many irregular features, most notably cytoplasmic extensions (pseudopods, or blebs) from their apical surface. Distal to the site of obstruction, morphological anomalies which resembled those seen after experimental oesophageal ligation were found. These included delayed disappearance of the apical endocytic network, disrupted or absent microvilli, glycogen accumulation and inappropriate cell extrusion. Proximal to the obstruction, where stasis of swallowed fluid occurs, distension and abnormal intestinal development ensues. Distal to the obstruction where the intestine develops in the absence of swallowed fluid, development is also abnormal. The anomalies resemble those noted after oesophageal ligation in utero, and possibly are the results of reduced cellular nutrition. These results suggest that fetal ingestion provides the developing gastrointestinal tract with an important stimulus for normal growth.     

Synchronous intestinal tumors: aggressive jejunal carcinoid and sigmoid malignant polyp

Association of aggressive jejunal carcinoid tumors and other primary gastrointestinal neoplasms are rarely observed. We describe the case of a synchronous jejunal carcinoid tumor and two colorectal polyps in a 78-year old woman. Surgical intervention was performed for the colorectal tumors and the carcinoid was incidentally found. It was well differentiated but was accompanied by lymph node metastasis and peritoneal carcinomatosis. In this case, the prognosis was not depending by the colorectal tumors but the aggressive feature of jejunal carcinoid lead to patient's death.     

Increased intestinal permeability in bronchial asthma

T lymphocytes are a major component of bronchial inflammatory processes in asthma. Because lymphocytes have the ability to migrate from one mucosal site to another, we initiated this prospective study to demonstrate mucosal abnormalities of the digestive barrier in asthma. To establish this we studied intestinal permeability in a group of 37 patients with asthma (21 allergic and 16 nonallergic) by measuring chromium 51–labeled ethylenediaminetetraacetatic acid (CrEDTA) urinary recovery. The results were compared with those obtained in a group of 13 nonasthmatic patients with chronic obstructive pulmonary disease and 26 healthy control subjects. Urinary recovery of CrEDTA was significantly higher in patients with asthma (2.5% ± 1.95%) than in patients with chronic obstructive pulmonary disease (1.16% ± 0.48%) and healthy control subjects (1.36% ± 0.14%). There was no significant difference in intestinal permeability between patients with allergic asthma (2.94% ± 2.4%) and those with nonallergic asthma (1.92% ± 0.9%). Intestinal permeability was not correlated with the severity of asthma as measured by FEV₁. Similarly, intestinal permeability did not significantly vary according to Aas score or steroid treatment. Serum IgE values and eosinophil blood count were not correlated with intestinal permeability. Intestinal permeability was evaluated sequentially in seven patients with asthma (4 allergic and 3 nonallergic) with a mean interval of 7.6 months (range, 2 to 13 months) and did not significantly change. Our results support the hypothesis that a general defect of the whole mucosal system is present as a cause or a consequence of bronchial asthma. (J ALLERGY CLIN IMMUNOL 1996;97:1173-8.)     

Ageing and duodenal morphometry.

Small bowel morphometry was studied in 25 subjects under the age of 70 years and 22 over the age of 70. There was no evidence of malabsorption or malnutrition in either group. Two distal duodenal endoscopic biopsy specimens were examined morphometrically. There were no significant correlations between age and areas of duodenal surface epithelium, crypts and lamina propria, heights of villi and surface epithelium, depth of crypts, crypt to villus ratio, number of intraepithelial lymphocytes, duodenal architecture, enterocytes, brush border and Brunner glands. Contrary to previous reports there was no evidence for a significant effect of age on proximal small bowel morphometry.     

Increase in human intestinal permeability following ingestion of hypertonic solutions.

1. A simple oral loading technique involving the ingestion of solutions containing lactulose is described. Timed urinary excretion of lactulose, which is non-metabolizable, is used as an indicator of intestinal permeability, and measured by quantitative paper chromatography. 2. This technique has been used to investigate the intestinal permeability of apparently healthy adults following the ingestion of solutions made hypertonic by the addition of the solutes sucrose, glucose, mannitol, glycerol, urea and sodium chloride. 3. These experiments show that intestinal permeability to lactulose increases as the solute concentration in the ingested solution is increased. Susceptibility to this effect, though consistent for each individual, shows considerable variation between subjects. 4. Factors thought to be pernitent to the enhancement of intestinal permeability by hypertonic solutions, and some possible implications of this, are discussed.     

Use of morphometry and immunohistochemistry of small intestinal biopsy specimens in the diagnosis of food allergy.

Eight babies with cow's milk protein intolerance and malabsorption, ages ranging from 2 weeks to 6 months, and five adult patients with a history of food allergy were studied. In the jejunal biopsies of the eight children with cow's milk protein intolerance we found partial villous atrophy with an increased number of interepithelial lymphocytes as determined by morphometric analysis. In the five adult patients no morphological changes of the jejunal mucosa were found. However, immunoperoxidase staining revealed a markedly increased number of IgE containing cells in the lamina propria of all jejunal biopsies studied. This proved to be specific for young and adult patients with food allergy. It is concluded that immunohistochemistry of jejunal biopsy specimens is of considerable value in the diagnosis of food allergy.     

Rat jejunal mucosal response to histamine and anti-histaminesin vitro. Comparison with antigen-induced changes during intestinal anaphylaxis

We previously showed that rats sensitized to egg albumin (EA) respond toin vivo intraluminal antigen-challenge with decreased net absorption of water and electrolytes and depletion of mucosal histamine. However, administration of anti-histamines did not prevent the transport abnormalities. The presentin vitro studies examined the effect of histamine to alter net ion transport and the ability of diphenhydramine (DPH) and cimetidine (CIM) to block the responses to both histamine and antigen. Control rat jejunum was mounted in Ussing chambers and histamine was added to the serosal side either in the absence or presence of DPH or CIM. In control tissues histamine caused a transient increase in short-circuit current (Isc) in a dose-dependent manner between 10^–5 and 10^–4 M which was blocked by 10^–5 M DPH but was unaffected by CIM in concentrations up to 10^–4 M. There was no response to EA. Jejunum from sensitized rats exposed to EA demonstrated a biphasic Isc response: a rapid transient rise followed by a somewhat less elevated but sustained component. In tissues pre-treated with DPH the initial peak Isc response was significantly reduced. In the presence of the neurotoxin, tetrodotoxin, the initial peak was unaffected but the sustained component was reduced. Our results indicate that H₁-receptors mediated the effects of histamine in rat jejunal mucosa but that during intestinal anaphylaxis histamine is responsible for only a portion of the antigen-induced transport abnormalities. Our data also suggest that IgE-mediated reactions in the intestine may involve an interaction between mast cell mediators and enteric nerves.This work was supported by the Medical Research Council of Canada.     

Alterations in rat jejunal permeability to a macromolecular tracer during a hyperosmotic load

The effects of intraluminal hyperosmolality on the intestinal permeability of a macromolecular tracer, horseradish peroxidase, was assessed in rats by light and electron microscopic cytochemistry. After 60 minutes of an intraluminal hypertonic perfusion of 600 mOsM mannitol, horseradish peroxidase was demonstrable in the intercellular spaces between adjacent absorptive epithelial cells of jejunal villi, along the microvillar brush border, in numerous pinocytotic vesicles, in multivesicular bodies, as well as in large lysosomes. Horseradish peroxidase was frequently found extending from the luminal surface of the cell through the tight junctional region and into more basal portions of the intercellular space. In occasional cells, fragments of the interdigitating plasma membranes of two adjacent absorptive cells appeared to bud off into the cytoplasm of one cell. In contrast, after 60 minutes of isotonic perfusion, horseradish peroxidase was confined to the microvillar brush border, a few pinocytotic vesicles, and occasional multivesicular bodies. These experiments suggest that the passage of macromolecules across the jejunal epithelium of adult rats is enhanced under conditions of luminal hyperosmotic stress. This may be due to an alteration in the functional integrity of the tight junctional macromolecular barrier or to an enhanced rate of pinocytosis.     

食物过敏后肠道通透性的研究

目的：研究食人过敏原后，不同时相下的肠道黏膜通透性变化。方法：将卵蛋白（OVA）致敏大鼠分成3组，分别以OVA（2mg/mL)经肠道攻击1、6和24h后经口投用β乳球蛋白（BLG）5mg/mL,2h后采血，用ELISA法测定血清中BLG的浓度，并对小肠黏膜浸润炎性细胞计数分类。结果：3组实验大鼠血清BLG浓度与对照组比较均增高，P值有显著差异（P＜0．01）；实验组间血清BLG的质量浓度比较无显著差异（P＞0．05），且实验组大鼠小肠黏膜内浸润的炎性细胞种类因食入后时相不同而有差异。结论：在食物过敏反应中，不论速发型或迟发型变态反应，肠道的通透性均增加，但引起的机制不同。     

Colchicine induces enhanced intestinal permeability in the rat

Intestinal permeability was determined in rats receiving colchicine 0.5 ± 0.15 mg day^-1 in drinking water (30 mg L^-1) for periods up to 23 days. The lactulose/mannitol method was used to determine whole gut permeability before and on days 2, 4, 8, 18 and 23 of colchicine administration. The 8-h urinary lactulose excretion following the test meal increased significantly in rats receiving colchicine, compared with the pretreatment value. Increased lactulose permeability was present after 2 days and remained stable throughout the experimental period. Mannitol urinary excretion was not changed. Colchicine increases intestinal tight junction permeability by an as yet undetermined mechanism.     

Chemical and physiological properties of polysucrose, a new marker of intestinal permeability to macromolecules.

To measure intestinal absorption of macromolecules we have developed a new technique employing synthetic polysucrose polymers as probe molecules. Polysucrose (PS) is water-soluble, nontoxic, resistant to intestinal enzymes, spherical and can be produced with a molecular weight distribution that relates to the size of many normal food proteins. Normally, a very small fraction of large molecules passes the exclusion barrier of the healthy intestine. Thus, quantification of resorbed macromolecules requires assays of high sensitivity. For detection of PS in various biological fluids, micro-ELISAs have been established. PS with a mean molecular weight of 14,700 daltons (PS 15,000) is rapidly excreted into the urine. Twenty-one healthy volunteers who orally ingested 1 g of this preparation showed a 12-hour urine excretion of 0.018% (interquartile range 0.014-0.022).     

Increase in rat intestinal permeability to endotoxin during hyperthermia

Summary Victims of heat stroke exhibit several clinical features which are also encountered in endotoxaemia. In order to investigate these similarities hyperthermic rats were used to explore the possibility that high body temperature results in increased permeability of intestinal wall to endotoxin. ¹²⁵I endotoxin was introduced into intestinal segments taken from non-heat exposed rats. The segments were then incubated at 37 C or 45 C. Intestinal segments from heat stressed rats were similarly prepared and incubated at 37 C. Leakage of endotoxin from segments taken from heat stressed rats was three times greater than from those from non-heat stressed rats, as were the segments from non-heat stressed rats which were incubated at 45 C. These results indicate that the intestinal membrane is damaged by heat and that an increase in outward leakage of microbial endotoxins from the gut then occurs. This might contribute to the pathophysiological picture of heatstroke.