Probiotic bacteria enhance murine and human intestinal epithelial barrier function

Gut changes attributed to ageing: effects on intestinal microflora

PURPOSE OF REVIEW

There is increased evidence of several impaired gastrointestinal functions with ageing. In the elderly, however, most gastrointestinal functions remain relatively intact because of the large reserve capacity of the intestine and the great secretion capacity of the pancreas. This review will focus on changes in gut microflora observed in the elderly and on the potential benefit of probiotics in this population.

RECENT FINDINGS

Recent studies suggest that age affects the intestinal microflora with a decrease in anaerobes and bifidobacteria population and an increase in enterobacteria. These changes and the reduced intestinal immunity of the aged may favour gastrointestinal infections that are frequent in the elderly. Clostridium difficile-associated diarrhoea, one of the most common nosocomial infections in the elderly, has a profound effect on morbidity, mortality and health costs. Probiotics may have interesting positive effects on intestinal function, and the efficacy of treatment with Lactobacilli and Saccharomyces boulardii in Clostridium difficile-associated diarrhoea has been well established in a recent meta-analysis. Studies performed in healthy elderly patients suggest that diet supplementation with probiotics may reduce the impaired immunity associated with ageing.

SUMMARY

Important changes in intestinal microflora of the elderly have recently been demonstrated and may have important clinical consequences. Further studies should be conducted to determine if the consumption of probiotics is associated with a lower infection rate and a higher effectiveness of vaccines.

The effect of fermented liquid feeding on the faecal microbiology and colostrum quality of farrowing sows

This study investigated the effects of fermented liquid feed (FLF) on the lactic acid bacteria (LAB):Coliform (L:C) ratio in the faeces of farrowing sows and the quality of sow colostrum. Eighteen multiparous sows were randomly allocated to one of three dietary treatments for approximately 2 weeks prior to farrowing and for 3 weeks after parturition. The three dietary treatments were dry pelleted feed (DPF), nonfermented liquid feed (NFLF), and fermented liquid feed (FLF). A rifampicin-resistant mutant of Lactobacillus plantarum was used to ferment liquid feed. Coliforms and lactic acid bacteria (LAB) in the faeces of farrowing sows and piglets were estimated by standard microbiological techniques. Intestinal epithelial cells (IEC-6) and blood lymphocytes were used to evaluate the mitogenic activity of colostral samples taken at parturition. Results demonstrated that while the LAB population was not significantly affected by dietary treatment, significant differences in coliform population were observed in the sow faecal samples taken 7 days after parturition. Faeces excreted from sows fed FLF had significantly (P < 0.001) lower numbers of coliforms than sows fed NFLF or DF. Piglets from sows fed FLF excreted faeces that were higher in LAB (7.7 vs. 7.3 log10 CFU g (-1); P < 0.01) and lower in coliforms (7.5 vs. 8.1 log10 CFU g (-1); P < 0.001) than faeces from the piglets of DF-fed dams. Colostrum from sows fed FLF had a significantly greater (P < 0.001) mitogenic activity on both intestinal cells (IEC-6) (79326 +/- 3069 CPM) and blood lymphocytes (1903 +/- 204 CPM) compared with colostrum from dry feed fed sows (53433 +/- 1568 and 1231 +/- 61.4 CPM, respectively). The combined effects of enhanced maternal/passive immunity and the reduction in the level of environmental contamination with faecal pathogens, achieved by FLF, may be important in achieving improved health status for both sows and piglets.

Variable response to probiotics in two models of experimental colitis in rats

BACKGROUND AND AIM

Clinical and experimental data suggest an important role for intestinal microflora in the pathogenesis of inflammatory bowel disease, and probiotics have been shown to ameliorate pouchitis. We evaluated the effect of different preparations of probiotic bacteria on experimental colitis in rats.

METHODS

Rats were treated daily intragastrically with two probiotic preparations, VSL#3 or strain GG (LGG), 7 days before induction of colitis and for another week thereafter. Colitis was induced by intracolonic administration of either dinitrobenzene sulfonic acid (DNBS) or iodoacetamide. Rats were killed 7 days after induction of colitis, the colon isolated, washed, weighed, lesion area measured, and mucosa processed for determination of myeloperoxidase (MPO) and nitric oxide synthase (NOS) activities and prostaglandin E2 (PGE2) generation.

RESULTS

In rats cotreated with VSL#3 or LGG and iodoacetamide, there was a significant decrease in the lesion area, 98 +/- 37 mm and 142 +/- 43 mm, respectively, as compared with 342 +/- 66 mm in the control group. Colonic wet weight significantly decreased to 1.3 +/- 0.1 g/10 cm and 1.4 +/- 0.1 g/10 cm, respectively, as compared with 1.7 +/- 0.1 g/10 cm. There was also a significant decrease in PGE2 generation, MPO, and NOS activities in the VSL#3 and LGG treatment groups. Presence of VSL#3 bacteria in the rat's colon was confirmed by culture and polymerase chain reaction (PCR) amplification. Neither probiotic preparation had an effect on the extent of colonic damage in DNBS-induced colitis.

CONCLUSION

Both VSL#3 and LGG significantly ameliorated colitis induced by the sulfhydryl-blocker iodoacetamide, but had no effect on the immune-mediated DNBS-induced colitis. The results suggest a possible role for sulfhydryl compounds in the protective effect of probiotic bacteria, and support their use in patients with inflammatory bowel disease.

Normal Breast Milk Limits the Development of Colitis in IL-10-Deficient Mice

BACKGROUND AND AIMS

This study examined the role of breast milk in neonatal bacterial colonization of the colon and disease progression in IL-10-deficient mice.

METHODS

IL-10-deficient mice were cross-fostered at birth and raised until weaning with a normal mother. Results were compared with normal pups cross-fostered to an IL-10-deficient mother. Mice were examined at various ages for histologic disease, levels of colonic bacteria, and proinflammatory cytokine secretion.

RESULTS

IL-10-deficient mice that had been cross-fostered to a normal mother demonstrated normal levels of colonic adherent bacteria and reduced TNFalpha and IFN gamma secretion at 2 to 12 weeks of age. Histologic disease was significantly reduced up to 12 weeks of age. Normal mice cross-fostered to an IL-10-deficient mother had increased levels of adherent bacteria at 2 and 4 weeks and increased IFN gamma secretion. This group also demonstrated slight inflammation up until 12 weeks of age.

CONCLUSION

Breast milk has a role in neonatal bacterial colonization. Changing the luminal environment of IL-10-deficient mice during the neonatal period alters the natural disease course.

Effect of different probiotic preparations on anti-helicobacter pylori therapy-related side effects: a parallel group, triple blind, placebo-controlled study

OBJECTIVES

Several studies show that probiotics may prevent side effects during therapy against Helicobacter pylori (H. pylori). Other reports indicate competitive interaction between some probiotics and H. pylori. We compared efficacy of two different probiotics and one probiotic combination with placebo for preventing anti-H. pylori therapy-related side effects and for improving the eradication rate.

METHODS

A total of 85 H. pylori positive, asymptomatic patients were randomized in four groups to receive probiotic or placebo both during and for 7 days after a 1-wk triple therapy scheme (rabeprazole 20 mg b.id., clarithromycin 500 mg b.i.d., and tinidazole 500 mg b.i.d.). Group I (n = 21) received Lactobacillus GG; group II (n = 22), Saccharomyces boulardii; group III (n = 21), a combination of Lactobacillus spp. and biphidobacteria; and group IV (n = 21), placebo. Subjects filled in weekly symptom questionnaires for 4 wk. Blinded investigators collected and analyzed data. H. pylori status was rechecked after 5-7 wk.

RESULTS

Side effects occurred mainly during the eradication week. None of them caused therapy discontinuation. In all probiotic-supplemented groups, there was a significantly lower incidence of diarrhea and taste disturbance during the eradication week with respect to the placebo group. Overall assessment of tolerability was significantly better in the actively treated patients than in the placebo group. No differences in the incidence of side effects between the probiotic groups were observed. The H. pylori eradication rate was almost identical between the probiotic and placebo groups.

CONCLUSIONS

All the probiotics used were superior to placebo for side effect prevention, but were not associated with better compliance with antibiotic therapy. The effect of probiotic supplementation on side effects during anti-H. pylori regimens seemed to be independent of the probiotic species used.

Down-regulation of intestinal lymphocyte activation and Th1 cytokine production by antibiotic therapy in a murine model of Crohn's disease

Resident intestinal bacteria likely play an important role in the pathogenesis of Crohn's disease through their interaction with the gut immune system. SAMP1/YitFc mice spontaneously develop chronic, discontinuous, transmural ileitis with many features similar to Crohn's disease. The aim of this study was to determine the effects and elucidate the mechanisms of action of antibiotic treatment in the SAMP1/YitFc mouse model of ileitis. Mice were treated orally with ciprofloxacin and metronidazole before the development of ileitis (prevention protocol) or after ileitis was fully established (treatment protocol). Terminal ilea were harvested for histological scoring, and lamina propria and mesenteric lymph node cells were isolated for analysis of activation markers and cytokine production. Antibiotic therapy significantly decreased the severity of ileitis both in the prevention (40% reduction, p < 0.05) and the treatment (25% reduction, p < 0.01) protocols, compared with untreated, control mice. These effects were associated with a decreased percentage of CD4(+)/CD45RB(high) lymphocytes in mesenteric lymph nodes of antibiotic-treated mice, as well as decreased production of IFN-gamma (prevention: 0.53 +/- 0.21 vs 1.84 +/- 0.04 ng/ml, p < 0.05; treatment: 8.4 +/- 0.4 vs 12.4 +/- 0.7 ng/ml, p < 0.005) and TNF (prevention: 61.5 +/- 13 vs 134 +/- 19 pg/ml, p < 0.01; treatment: 333.5 +/- 11 vs 496 +/- 20 pg/ml, p < 0.001). The number of activated lamina propria lymphocytes was also reduced after antibiotic treatment. In conclusion, antibiotic therapy significantly ameliorates the severity of ileitis in SAMP1/YitFc mice by a mechanism involving down-regulation of activated gut lymphocytes and inhibition of intestinal Th1 cytokine production.

Immunologic basis for diarrhea

Diarrhea is a common sequela of deregulated immune pathways underlying the wide range of intestinal acute and chronic diseases. The ongoing investigation of novel immune components and susceptibility factors allows better understanding of these pathologic mechanisms and continues to advance therapeutic options.

The place of probiotics in human intestinal infections

A number of studies have been carried out on the effect of several probiotic species on treatment and prevention of intestinal infections. The most commonly used microorganisms are lactic-acid producing bacteria such as lactobacilli and bifidobacteria belonging to the human normal microflora. In vitro and animal studies have shown that probiotic microorganisms interfere with the colonisation of Helicobacter pylori and of enteropathogenic microorganisms. In humans the significance is more uncertain. Clinically significant benefits of probiotics have been demonstrated in the treatment of rotavirus induced diarrhoea and of Saccharomyces boulardii in the prevention of antibiotic-associated diarrhoea (AAD). In patients suffering from inflammatory bowel disease, several probiotic strains have been shown to be as effective as traditional medication in preventing relapses. Standardised and well performed studies are needed to elucidate further the mechanisms of action and the clinical significance of probiotics.

Pouchitis in Children: Therapeutic Options

Pouchitis is an unfortunate common complication of the ileal pouch-anal anastomosis procedure, an otherwise very attractive surgical option in patients with ulcerative colitis (UC). The fact that the same pouch in familial polyposis is hardly complicated by pouchitis suggests that the basic inflammatory process in UC might participate in the pathophysiology. We review the clinical features of pouchitis, the diagnostic approach, and the many therapeutic considerations, including more recent data on prebiotics and probiotics.

Review article: lactose--a potential prebiotic

Lactose maldigestion, which affects a large majority of the world's population, has been mostly linked with uncomfortable symptoms. In addition, dairy consumption is variably blamed or recommended for a number of ill effects. There is, however, emerging evidence that certain lactic acid-producing bacteria, which selectively consume prebiotics, may be beneficial against some lower intestinal diseases. Lactose maldigestion and lactose should perhaps be re-evaluated as a potential provider of such a prebiotic. This historical and observational review discusses lactose and argues the opinion that it has prebiotic potential. Moreover, in maldigesters, natural ingestion or lack thereof may be relevant in the pathogenesis of diseases such as colorectal cancer and inflammatory bowel diseases.

Advances in the medical therapy of inflammatory bowel disease

The medical therapy of inflammatory bowel disease (IBD) has advanced significantly over the past year. Serologic markers of IBD have been further investigated and better defined, showing some discriminatory power with potential therapeutic implications. Studies of azathioprine and 6-mercaptopurine metabolites will make it easier and safer to use these effective drugs. Clinical data using other immunomodulators, including 6-thioguanine, mycophenolate mofetil, cyclosporine, and tacrolimus, continue to accrue with positive results. Infliximab has become even more firmly established as a reliable and effective therapy for active and fistulizing Crohn disease and may even be helpful in some patients with resistant ulcerative colitis. However, the recognition of potential complications of infliximab therapy has increased with the accumulated clinical experience. Results from trials of other biologic therapies directed at tumor necrosis factor alpha have been disappointing so far, although preliminary studies with biologics directed at adhesion molecules are encouraging. Growing appreciation of the importance of the enteric microflora in IBD has led to a considerable interest in manipulating intestinal bacteria for therapeutic benefit, and trials of both probiotics and prebiotics show promise.

Immunopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by inflammation that results from the interaction between the various components of the mucosal immune system and the microenvironment. These components-lu}inal antigens, intestinal epithelial cells (IEC), lymphocytes, and cells of the innate and adaptive immune system and their secreted mediators (cytokines and chemokines)-contribute to the cascade of events that ends in intestinal and systemic damage in a genetically predisposed host. The origin of IBD is as yet unknown, but the beginning of the third millennium has brought several new insights into the immune aberrations in IBD. The progress achieved last year in each component of IBD pathogenesis will be reviewed. In each section, an attempt to develop correlations between experimental findings and human disease is made.

Shigella flexneri regulates tight junction-associated proteins in human intestinal epithelial cells

Shigella spp. are a group of Gram-negative enteric bacilli that cause acute dysentery in humans. We demonstrate that Shigella flexneri has evolved the ability to regulate functional components of tight junctions after interaction at the apical and basolateral pole of model intestinal epithelia. In the regulation of tight junctional protein assemblies, S. flexneri can engage serotype-specific mechanisms, which targets not only expression, but also cellular distribution and membrane association of components of tight junctions. Distinct mechanisms resulting in the regulation of tight junction-associated proteins are initiated after either apical or basolateral interactions. S. flexneri serotype 2a has the ability to remove claudin-1 from Triton X-insoluble protein fractions upon apical exposure to T-84 cell monolayers. S. flexneri serotype 2a and 5, but not the non-invasive Escherichia coli strain F-18, share the ability to regulate expression of ZO-1, ZO-2, E-cadherin and to dephosphorylate occludin. The disruption of tight junctions is dependent on direct interaction of living Shigella with intestinal epithelial cells and is supported by heat-stable secreted bacterial products. Intestinal epithelial cells have the ability to compensate in part for S. flexneri induced regulation of tight junction-associated proteins.

Anatomic and functional characteristics of the rat ileal pouch

BACKGROUND

The definitive operation for chronic ulcerative colitis (UC) and familial adenomatous polyposis is total proctocolectomy with ileal pouch-anal anastomosis (IPAA). Mild inflammation (pouchitis) is omnipresent in pouches and becomes severe in 50% of UC patients with IPAA. The etiology of pouchitis is likely due to combined genetic, microbial, and immunologic factors. Epithelial cell exposure to surgical trauma and/or to changes in intestinal bacterial composition may account for the inflammatory infiltrate. Progress in understanding pouchitis is restricted by the lack of suitable animal models.

METHODS

An ileal pouch-rectal anastomosis [IPRA] in rats was developed to reproduce a model of human IPAA and clinical, gross and histologic criteria were determined.

RESULTS

Many shared features with human ileal pouch were observed.

CONCLUSION

IPRA is an important in vivo model to study mechanisms of repair, defense and immunity that may contribute to pouchitis.

Probiotics in gastroenterology

Recent evidence has suggested the potential therapeutic role for probiotics in the prevention or treatment of gastrointestinal diseases. Several studies have shown that probiotics are of benefit in gastrointestinal infections, including viral diarrhea, Clostridium difficile-associated diarrhea, traveler's diarrhea, and antibiotic-associated diarrhea. Recent data support the potential beneficial therapeutic effect in inflammatory bowel disease as well. Other possible indications for probiotic treatment include Helicobacter pylori infection, irritable bowel syndrome, and radiotherapy-associated diarrhea. It is important to select well-characterized preparations; in fact, the viability and survival of many available preparations are unproven. More precise information on the mechanisms by which probiotic strains exert their beneficial effects in vivo is needed. This may provide the scientific rationale for the selection of the best probiotic strains to use in the performance of large, double-blind, controlled clinical trials.

[Effectiveness of hyperbaric oxygenation as a factor of increasing the resistance of the human body to space flight conditions]

In four experimental runs (30 test subjects in 407 tests), the beneficial effect of hyperbaric oxygenation (HBO) on flight tolerance was demonstrated. HBO sessions (7-8 sessions of an hour in duration during 10-12 days at pO2 = 2 atm) helped subjects with poor altitude tolerance to increase the altitude ceiling by 1 km and reserve time at altitudes of 6-7 km by 3-4 min, the effect being persistent for 2-3 months. Statokinetic tolerance of subjects with medium motion sickness susceptibility grew by 2-2.5 times after the above HBO sessions. As compared to regular rest, the HBO treatment shortened two-fold the period of recovery of the health state and work capacity of operators, which went down during flight, and increased 15-20% the time of repeated work prior to failure in a stressful environment.