Massimo Montalto

Increased intestinal permeability and tight junction alterations in nonalcoholic fatty liver disease

The role played by the gut in nonalcoholic fatty liver disease (NAFLD) is still a matter of debate, although animal and human studies suggest that gut‐derived endotoxin may be important. We investigated intestinal permeability in patients with NAFLD and evaluated the correlations between this phenomenon and the stage of the disease, the integrity of tight junctions within the small intestine, and prevalence of small intestinal bacterial overgrowth (SIBO). We examined 35 consecutive patients with biopsy‐proven NAFLD, 27 with untreated celiac disease (as a model of intestinal hyperpermeability) and 24 healthy volunteers. We assessed the presence of SIBO by glucose breath testing (GBT), intestinal permeability by means of urinary excretion of 51Cr‐ethylene diamine tetraacetate (51Cr‐EDTA) test, and the integrity of tight junctions within the gut by immunohistochemical analysis of zona occludens‐1 (ZO‐1) expression in duodenal biopsy specimens. Patients with NAFLD had significantly increased gut permeability (compared with healthy subjects; P < 0.001) and a higher prevalence of SIBO, although both were lower than in the untreated celiac patients. In patients with NAFLD, both gut permeability and the prevalence of SIBO correlated with the severity of steatosis but not with presence of NASH. Conclusions: Our results provide the first evidence that NAFLD in humans is associated with increased gut permeability and that this abnormality is related to the increased prevalence of SIBO in these patients. The increased permeability appears to be caused by disruption of intercellular tight junctions in the intestine, and it may play an important role in the pathogenesis of hepatic fat deposition. (HEPATOLOGY 2009.)

Lactobacillus acidophilus protects tight junctions from aspirin damage in HT-29 cells

Background/Aims: Non-steroidal anti-inflammatory drugs cause enterocyte damage inducing an increase of intestinal permeability. Tight junctions are the key structures in the permeability of the intestinal mucosa. ZO-1 is a tight junction associated protein considered a good marker of their integrity. It has been suggested that probiotics could play a protective role in the intestinal barrier function. We determined, in vitro, whether the heat-killed Lactobacillus acidophilus strain LB (LaLB) with its spent culture supernatant protects tight junctions of HT-29 cells from aspirin (ASA) damage. Methods: HT-29 cells were treated with ASA alone or ASA and LaLB with its spent culture supernatant together. Morphological alterations of tight junctions were evaluated by immunofluorescence using an anti-ZO-1 antibody. Moreover, a semiquantitative assay for ZO-1 was performed by Western blot. Results: Immunofluorescence analysis showed a fragmented and granulous ZO-1 staining, after ASA treatment. Using both ASA and LaLB with its spent culture supernatant together, we found a fine continuous linear web at cell-cell contacts similarly to control. Western blot revealed that ASA inhibited ZO-1 expression and LaLB with its spent culture supernatant counteracted this effect. Conclusions: This pilot study shows, for the first time, the protective effect of LaLB with its spent culture supernatant on tight junctions from ASA damage. These results suggest that probiotics could play a role in the prevention of ASA-induced alterations of intestinal permeability.

Probiotic treatment increases salivary counts of lactobacilli: a double-blind, randomized, controlled study.

Background/Aims: Lactobacilli are used in the prevention and treatment of several diseases, but they are also known to play a role in the pathogenesis of dental caries. The aim of our study was to evaluate whether the oral administration of lactobacilli could change the salivary counts of these bacteria compared with placebo. Moreover, lactobacilli were administered in liquid and in capsule form to determine the role of direct contact with the oral cavity. Methods: Thirty-five healthy volunteers were randomized into three groups to receive lactobacilli and/or placebo for 45 days: group A (n = 14) received probiotics in capsules and placebo in liquid form; group B (n = 16) took liquid probiotics and placebo in capsules, and group C (n = 5) used placebo in both liquid and capsule form. Streptococcus mutans populations served as control. The salivary counts of lactobacilli and S. mutans were measured semi-quantitatively using the CRT® bacteria kit. Results: Compared with placebo, the oral administration of probiotics, both in capsules and in liquid form, significantly increases salivary counts of lactobacilli (p = 0.005 and p = 0.02, respectively). S. mutans populations were not significantly modified. Conclusions: The increased salivary counts of lactobacilli may indicate the need to closely monitor the dental health of patients undergoing long-term probiotics treatment, even when this treatment is administrated in a form that avoids direct contact with the oral cavity.

Direct visualization of intestinal villi by high-resolution magnifying upper endoscopy: a validation study

BACKGROUND New generation videoendoscopes potentially may visualize duodenal villi. This study compared endoscopic findings with this type of instrument to the histopathologic evaluation of duodenal villi. METHODS A total of 191 patients underwent upper endoscopy for the purpose of obtaining duodenal biopsy specimens. The findings were assessed independently by 3 experienced observers by using a commercially available, high-resolution, high-magnifying (x2) videoendoscope. The duodenal villous profile was determined by endoscopic magnification and by endoscopic magnification after filling the duodenum with water. With both endoscopic magnification and endoscopic magnification after filling the duodenum with water, villous patterns were scored as the following: definitely present, partially present, or definitely absent. Villous patterns also were histopathologically scored as the following: normal, partial villous pattern, or total villous atrophy. RESULTS Interobserver variability was excellent (kappa = 0.93). The concordance between either endoscopic magnification or endoscopic magnification after filling the duodenum with water and histology was 100% for presence/absence of villi. The sensitivity, the specificity, and the positive and negative predictive values of endoscopic magnification for detection of any villous abnormality were 95%, 99%, 95%, and 99%, respectively; the respective values of endoscopic magnification after filling the duodenum with water were 95%, 98%, 92%, and 99%. CONCLUSIONS High-resolution magnifying upper endoscopy can reliably predict the presence or the absence of duodenal villi.

Systematic review: sprue-like enteropathy associated with olmesartan

The onset of a sprue‐like enteropathy in association with olmesartan therapy has been recently reported.

Role of Dental Plaque in the Transmission of helicobacter Pylori Infection

With regard to the role of dental plaque in the transmission of Helicobacter pylori infection, data from the literature vary greatly, owing to differences in sample collection and H. pylori-detecting techniques. Using the polymerase chain reaction (PCR), we have determined the incidence of H. pylori colonization in the dental plaque of 31 consecutive patients who underwent gastroscopy. The patients were divided into two groups on the basis of H. pylori infection, determined by Giemsa stain and the rapid urease test: group A made up of 21 H. pylori-positive patients and group B with 10 H. pylori-negative patients. Our PCR assay of dental plaque samples proved negative in all group A subjects but was positive in only one patient in group B. In our study, we found that H. pylori had a low prevalence (3.2%) in the oral cavity, with no significant relationship between gastric mucosa and dental plaque colonization. More comprehensive studies are needed to determine whether dental plaque is an important reservoir in the epidemiology of H. pylori-induced gastric disease.

Intestinal microbiota and its functions

Abstract The digestive tract harbours the largest and most complex microbial community of the human body, the intestinal microbiota, including about 800 different bacteria species. The distribution of this microflora is uneven, with highest concentrations in the colon. Bacterial colonization of human gut by environmental microbes, beginning immediately after birth, becomes more complex with increasing age, with a high degree of variability among human individuals. The gastrointestinal tract is the main site where environmental microorganisms and antigens interact with the host, through intensive cross-talks. Gut microbiota is essential for intestinal development, homeostasis and protection against pathogenic challenge; moreover, gut microbes are involved in metabolic reactions, with harvest of energy ingested but not digested by the host; they have also trophic effects on the intestinal epithelium, by favouring the development of intestinal microvilli, and play a fundamental role in the maturation of the hosts innate and adaptive immune responses.

Cardiopulmonary bypass in man: role of the intestine in a self-limiting inflammatory response with demonstrable bacterial translocation

BACKGROUND Cardiopulmonary bypass provokes a systemic inflammatory reaction that, in 1% to 2% of all cases, leads to multiorgan disfunction. The aim of this study was to evaluate the possible role of the intestine in the pathogenesis and development of this reaction. METHODS Eleven selected patients scheduled for elective coronary artery bypass graft surgery were enrolled in a open, prospective clinical study. Gastric tonometry, chromium-labeled test and double sugar intestinal absorption tests, polymerase chain reaction microbial DNA test, and measurement of cytokines and transcriptional factor (nuclear factor kappaB) activation were performed. RESULTS During the postoperative period, gastric pH remained stable (range,7.2 to 7.3). The partial pressure for carbon dioxide gradient between the gastric mucosa and arterial blood increased significantly (from 1 to 23 mm Hg), peaking in the sixth postoperative hour. Interleukin 6 increased significantly over basal levels, peaking 3 hours after cardiopulmonary bypass (96.3 versus 24 pg/mL). Nuclear factor kappaB never reached levels higher than those observed after lipopolysaccharide stimulation. Escherichia coli translocation was documented in 10 patients: in eight cases from removal of aortic cross-clamps and in two cases from the first postoperative hour. With respect to basal value (6.4%), the urine collection revealed a significant increase in excretion of the radioisotope during the first 24 hours after surgery (39.1%), although there were no significant variations with the double sugar test. CONCLUSIONS The results obtained showed a correlation between the damage of the gastrointestinal mucosa, subsequent increased permeability, E coli bacteremia, and the activation of a self-limited inflammatory response in the absence of significant macrocirculatory changes and postoperative complications.

Immunohistochemical Analysis of ZO-1 in the Duodenal Mucosa of Patients with Untreated and Treated Celiac Disease

Background/Aim: ZO-1 is a good marker for tight junction integrity which may be damaged in many intestinal diseases. ZO-1 can also accumulate in the cellular nucleus in addition to sites of cell-cell contact, suggesting a potential role in cellular proliferation and differentiation. We evaluated the expression and distribution of ZO-1 in patients with celiac disease before and after a gluten-free diet. Methods: The ZO-1 expression was evaluated semiquantitatively by means of immunohistochemical analysis in duodenal bioptic specimens of 10 consecutive patients with celiac disease before and after a gluten-free diet and in 10 controls. Furthermore, the nuclear staining was analyzed quantitatively, evaluating 3,000 cells for each count, and it was expressed as a percentage of labeled nuclei over the total of analyzed cells. Results: The intestinal mucosa of untreated celiac disease patients shows a globally lower ZO-1 labeling than that of controls. The expression of ZO-1 in the treated celiac mucosa did not differ significantly from normal intestinal mucosa of healthy subjects. At the crypt level of untreated celiac mucosa, a low intensity of nuclear labeling (1.75 ± 0.32%) was found, while in both treated celiac disease patients and in normal subjects we observed a statistically significant higher percentage of strongly labeled nuclei (53.72 ± 6.30% and 56.79 ± 5.45%, respectively; p = 0.0002). Conclusions: Our data show a global underexpression of ZO-1 in the duodenal mucosa of active celiac disease patients. Gluten withdrawal allows a normalization of the ZO-1 expression in treated celiac disease patients. Furthermore, the particular pattern of ZO-1 resembles the cellular distribution in undifferentiated cells and may be the result of immaturity of the enterocytes in untreated celiac sprue.

Prevention and treatment of low-grade B-cell primary gastric lymphoma by anti-H. pylori therapy.

Mucosa-associated lymphoid tissue (MALT) showing a follicular structure can develop in the gastric mucosa as a response to Helicobacter pylori infection. We emphasize the importance of anti-H. pylori antibiotic therapy in the elimination of acquired MALT. Of the 200 patients studied, acquired MALT was found in 70 of the 151 H. pylori-positive patients, whereas it was present in only five of the 49 H. pylori-negative patients. Thirty-eight H. pylori-positive and MALT-positive patients were treated with antibiotic therapy and reevaluated after 6 months: 21 patients were H. pylori negative/MALT negative, 12 were H. pylori positive/MALT positive, four were H. pylori negative/MALT positive, one was H. pylori positive/MALT negative. In the control group (n = 20), H. pylori and acquired MALT were still present at follow-up. One patient with histological and immunohistochemical evidence of low-grade B-cell gastric MALT lymphoma underwent antibiotic treatment and was reexamined after 8, 12, and 24 weeks: histological examination of biopsy samples showed regression of the MALT lymphoma in tandem with the disappearance of H. pylori colonization. Our data confirm the correlation between H. pylori infection and acquired MALT, as documented by the ability of antibiotic therapy to induce the disappearance of acquired MALT and regression of MALT lymphoma. Considering the potential evolution of MALT into low-grade B-cell MALT lymphoma, H. pylori eradication should play a role in the prevention of this tumor.