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PubMed2004

Review article: gut flora and inflammatory bowel disease.

The pathogenesis of inflammatory bowel disease involves interactions between the host susceptibility, mucosal immunity and intestinal microflora. There is therefore great interest in the changes in the endogenous flora in inflammatory bowel disease patients and in the establishment of potential genetic variations in host responses to endogenous bacteria. In this review, we summarize the modifications in the various regional ecosystems in the gastrointestinal tract during inflammatory bowel disease (luminal bacteria in faeces or inside the gastrointestinal tract, bacteria in mucus and bacteria directly attached to the mucosa). Results were obtained following a 'candidate microorganism strategy' and, as is occurring increasingly frequently, following a 'full description strategy', which has progressed largely due to the development of culture-independent techniques. The possibility of modifying the ecosystem using prebiotics or probiotics offers hope for new treatment developments, particularly in the prevention of relapse.

Bacteria↗
PubMed2003

Effects of intestinal microflora and the environment on the development of asthma and allergy.

The aim of previous research into the causes of allergic diseases, including asthma was mostly to identify potential risk factors in the environment. No major risk factors have been identified, however. Over the past 10 years, focus has, therefore, more been directed towards protective factors that could enhance the development of tolerance to allergens which were previously encountered early in life, but are now lost in modern affluent societies. In particular, the role of childhood infections has been discussed, but so far these studies have not been conclusive. Recent epidemiological studies and experimental research suggest that the microbial environment and exposure to microbial products in infancy modifies immune responses and enhances the development of tolerance to ubiquitous allergens. The intestinal microflora may play a particular role in this respect, as it is the major external driving force in the maturation of the immune system after birth, and animal experiments have shown it to be a prerequisite for normal development of oral tolerance. Recent studies have shown differences in the composition of the microflora between healthy and allergic infants in countries with a high and low prevalence of allergies and between healthy and allergic infants within such countries. These differences are apparent within the first week of life and thus precede clinical symptoms. The use of live microorganisms that might be beneficial to health has a long tradition and the safety is well documented. Very recently, several prospective intervention studies, modifying the gut flora from birth have yielded encouraging results and may suggest a new mode of primary prevention of allergy in the future.

Animals↗
PubMed1993

[The role of bacterial adhesion in urinary tract infections].

Bacteria adhere to and colonize almost any surface. The mechanism by which bacteria interact with the mucosal surface appears to involve specific molecular ligands or adhesins on the surface of the bacteria that interlock with specific receptor molecules on the surface to be colonized. Material adhesion allows the microorganisms to resist being washed away by the fluids and secretions that bathe mucosal surfaces and is a necessary prerequisite to growth, colonization, and subsequent infection. Many examples of the role of bacterial adherence to tissues of the host have been reported in the literature. The classic study is that of Smith and Linggood, who demonstrated that toxin-producing enteropathogenic Escherichia coli, which cause diarrhoea in swine, adhere selectively to the mucosal surfaces of the small intestine. Adherence is mediated by hair-like pili projecting from the surface of the cells. Production of these pili is controlled by a specific plasmid, the loss of which renders the cells avirulent although they continue to produce toxin. In addition, antibody to the pilus antigen prevents adherence and protects piglets against challenge with the piliated organisms. Thus, the adhesin is an essential virulence factor in enteropathogenic E. coli infections in swine. Similar studies in a variety of diseases including enterotoxigenic E. coli infections in men and rheumatic fever support the concept that specific bacterial adherence to host tissues is an important characteristic of many pathogenic microorganisms.

Animals↗
PubMed1996

Liver microsomal levels of cytochrome P450IA1 as biomarker for exposure and bioavailability of soil-bound polycyclic aromatic hydrocarbons.

The bioavailability of soil-bound polycyclic aromatic hydrocarbons (PAHs) for mammalian species was studied with rats fed with a diet containing contaminated soil preparations. The extent of cytochrome P450IA1 (CYP1A1) induction in the liver correlated with the amount of 5- and 6-ring PAHs in the soil samples but not with the total PAH content. Other cytochromes P450 were much less affected by the soil-contaminants. The highest induction of CYP1A1 was obtained with a sample containing 274 mg 5- and 6-ring PAH/kg soil, resulting in a nearly 360-fold increase in the ethoxyresorufin deethylase (EROD) activity. In a semilogarithmic plot, a linear correlation was found between the 5- and 6-ring PAH concentration in the soil and the microsomal CYP1A1 content. As a model for the action of intestinal fluids, soil samples were extracted by bile acid solution. In these experiments, the selectivity in the solubilization of individual PAHs parallels that of toluene extraction, although the yield is lower than the latter and varies with the soil sample. The bioavailability of PAHs for microorganisms, but not for mammals, was shown to be considerably reduced in the presence of high total organic carbon (TOC) values of the soil samples. This may have implications for decontamination strategies, diminishing the effectiveness of biological decontamination in cases with high TOC values. The data suggest that CYP1A1 induction in rats is a parameter that may be useful in risk assessments of contaminated soils for mammalian species.

Animals↗
PubMed2003

Probiotics, Irritable Bowel Syndrome, and Inflammatory Bowel Disease.

Probiotics are live, microbial food supplements that benefit the host animal by improving intestinal microbial balance. Their major role in preventing and treating gastrointestinal disease appears to be from their effect on the immune process, protection against abnormal invasive bacteria, and in the production of short-chain fatty acids from starch and non-starch polysaccharides. Probiotic microorganisms are administered in food supplements and yogurts. They are also now sold in the form of capsules and powders. There is great variation in the microorganisms in the various supplements. It is important to understand that all probiotic products are different. Some contain a single organism and others contain multiple organisms. Therapeutic results have been achieved with various probiotics in different diseases. In the treatment of inflammatory bowel diseases (IBD), success has been reported with Escherichia coli Nissle strain in ulcerative colitis, and with a multiple organism product, VSL#3 (VSL Pharmaceuticals, Fort Lauderdale, FL), in Crohn's disease and pouchitis. Initial reports in irritable bowel syndrome (IBS) have resulted in encouraging results with the use of E. coli Nissle strain, and recently with multiple organism probiotic supplements. However, caution must still apply to the use of probiotics in IBD and IBS because the reports and the number of patients treated are limited.

Journal Article↗
PubMed2001

Pathologic and physiologic interactions of bacteria with the gastrointestinal epithelium.

Communication between microorganisms and the gastrointestinal epithelium, ie, bacterial-epithelial "crosstalk," is examined. Because most basic research on the molecular interaction of bacteria with the gut epithelium relates to pathogen-enterocyte interaction, crosstalk with pathologic bacterial is considered in detail. Through their interactions with the intestinal epithelium, pathogens can modify epithelium function to enhance their penetration across the epithelial barrier and to exploit mucosal host defenses for their own benefit. Three representative pathogens are used to illustrate the various adaptive techniques used to colonize and penetrate the mucosal barrier. Salmonella enterica typhimurium interacts with the physiologic receptor for epidermal growth factor to co-opt the receptor's signal transduction mechanisms. Enteropathic Escherichia coli secretes a receptor (type III secretion) into the microvillus surface of enterocytes that disrupts the microvillus and alters its actin structure to form a dome-like anchoring site. Shigella flexneri is used to illustrate how pathogens use the follicular epithelial cell (M cell), the physiologic conduit for antigens to reach gut associated-lymphoid tissues, for penetration of the epithelial barrier. Shigella organisms attached to M cells use their endocytotic properties to enter the cell. Once inside the cell, the organism lyses the endocytic vacuole and co-opts actin and myosin to form a propelling tail for further penetration of the epithelium through the basolateral surface. Probiotics can protect the intestine by competing with pathogens for attachment, strengthening tight junctions between enterocytes, and enhancing the mucosal immune response to pathogens. However, additional molecular studies are needed to define more precisely the mechanism of probiotic-epithelial crosstalk.

Escherichia coli↗
PubMed1999

Molecular methods for the analysis of Clostridium perfringens relevant to food hygiene.

Clostridium perfringens continues to be a common cause of food-borne disease. It produces an enterotoxin (CPE) which is released upon lysis of the vegetative cell during sporulation in the intestinal tract. Catering premises with insufficient cooling and reheating devices often seem to be the cause of outbreaks of C. perfringens food poisoning. Typing of C. perfringens is of great importance for investigating sources of food poisoning cases and for studying the epidemiology of this microorganism. This report describes the examination of 155 C. perfringens isolates by molecular methods. Isolates were taken from 10 food poisoning outbreaks and cases (n = 34, food and fecal isolates) and from meat and fish pastes (n = 121). Isolates were characterized by plasmid profiling, ribotyping, and/or macrorestriction analysis by pulsed-field gel electrophoresis (PFGE). Results show that all three methods are suitable for classifying C. perfringens isolates below the species level. Ribopatterns and PFGE patterns can be interpreted more easily than plasmid profiling results and can be recommended for contamination studies and epidemiologic investigation of food poisonings associated with C. perfringens.

Animals↗
PubMedDate not supplied

Microbiological characterization of freatobiont organisms: trial of an analytical protocol and hygienic implications.

The objective of the present study lies in verifing the applicability of an analytical protocol to characterize the microbiology of the surface and gut of freatobiont organisms. The fundamental hypothesis of the study is that the subsurface microinvertebrates represent a protective condition for bacteria, whose presence in potable spring water is rigorously excluded by european standards of quality. The study was conducted between August 1996 and March 1998. Sediment samples were collected from the spring system of "Presciano", whose waters come from the regional aquifer of the Gran Sasso Massif in Italy (L'Aquila, Abruzzo). Drawings of samples were conducted at two different depths (-70 cm and -150 cm). The extration of the fauna (including copepodes) from sediments were achieved with the aid of a Wild M3 microscope. Isolate freatobiont organisms were placed in a sterile Petri plate and subjected to three washings. The liquids of the second and third washings were microbiological analyzed proceeding, in the course of the third washing, to squash the organisms with the aid of a sterile iron handle. Among the microinvertebrates, the copepod Harpacticoida Nitocrella pescei is the most represented species from the two levels of depth. In all, were isolated and identified 106 bacterial species; of these species only 12 (11.3%) did not show any adaptation to the temperature of 35 degrees C. The analytical protocol permitted to make evident a different distribution of microbial species between the two kinds of washing liquids, and this leads to considerate appropriate the adopted protocol. Even if the number of sediment samples analyzed was a few it was identified a great variety of microbial genera and species the greater part of which were mesophilic. This is a consequence of an adaptability that could be favoured by the presence of freatobiont fauna and that concern even microorganisms usually considered "faecal contamination indicators".

Adaptation, Physiological↗
PubMed1975

[Comparative study of neuraminidases from "Diplococcus pneumoniae" and "Clostridium perfringens"].

Neuraminidases have been purified from the culture medium of two microorganisms, one aerobic, Diplococcus neumoniae, the other anaerobic, Clostridium perfringens. The enzymatic properties of the 2 neuraminidases have been studied (pH optimum; effect of cations; activity toward different substrates: neuraminyllactose, dilactaminyllacto-N-tetraose, gangliosides, alpha1-acid glycoprotein, Collocalia glycoprotein, ovine submaxillary mucin, porcin intestinal and human bronchial mucins).

Cations, Divalent↗
PubMed1975

Bacteriological quality control in laboratory animals.

For monitoring health status of conventional laboratory animals, weekly samples should be examined of at least 2-5% of animals of each room. Dissecting method, bacteriological cultural technique and different selective media have been described. The significance of microorganisms and their relation to clinical signs, mode of infection and animals affected have been summarised in tabulated form.

Animals↗
PubMed2006

Analysis of chicken cytokine and chemokine gene expression following Eimeria acervulina and Eimeria tenella infections.

The expression levels of mRNA encoding a panel of 28 chicken cytokines and chemokines were quantified in intestinal lymphocytes following Eimeria acervulina and Eimeria tenella primary and secondary infections. Compared with uninfected controls, transcripts of the pro-inflammatory cytokines IFN-alpha, IL-1beta, IL-6, and IL-17 were increased up to 2020-fold following primary infection. By contrast, following secondary infection by either microorganism, pro-inflammatory mRNAs levels were relatively unchanged (< or = 20-fold). Transcripts encoding the Th1 and Th1 regulatory cytokines IFN-gamma, IL-2, IL-10, IL-12, IL-15, IL-16, and IL-18 were uniformly increased 14-2471-fold after E. acervulina primary infection, but either unchanged (IL-15, IL-16, IL-18), increased (IFN-gamma, IL-10, IL-12), or decreased (IL-2) following E. tenella primary infection. Following secondary infections, Th1 cytokine mRNA levels were relatively unchanged, with the exception of IL-12 which was increased 1.5 x 10(5)-fold after E. acervulina and decreased 5.1 x 10(4)-fold after E. tenella infection. Transcripts for the Th2 or Th2 regulatory cytokines IL-3 and GM-CSF were increased up to 327-fold following primary or secondary infection with both parasites, while IL-4 and IL-13 mRNAs were decreased 25- to 2 x 10(5)-fold after primary or secondary infection. The dynamics of chicken chemokine expression revealed modest changes (<100-fold) following primary or secondary infection except for lymphotactin. When lymphocyte subpopulations were similarly analyzed, IFN-gamma, IL-2, IL-3, IL-15, and MIF were most highly increased in TCR2(+) cells following E. acervulina infection, while TCR1(+) cells only expressed high levels of IL-16 following E. tenella infection. In contrast, CD4(+) cells only expressed highest levels of IL-10 after E. acervulina infection, whereas these cells produced abundant transcripts for IFN-gamma, IL-3, IL-15, and MIF after E. tenella infection. We conclude that coccidiosis induces a diverse and robust primary cytokine/chemokine response, but a more subdued secondary response.

Animals↗
PubMed1983

Relationship between morphological findings and function of the small intestine in familial amyloidosis with polyneuropathy.

Twenty-seven patients with familial amyloidosis with polyneuropathy were studied with regard to the morphology of the small intestine, and this was correlated to symptoms and malabsorption features. The mucosa was normal in all cases investigated by the dissecting microscope, the light microscope, and the scanning electron microscope. Amyloid was demonstrated in 83% of the cases by the presence of green birefringent material in the biopsy specimens stained with alkaline Congo red and examined in polarized light. Nineteen patients had steatorrhea, and 12 had pathological D-xylose test results. The degree of amyloid infiltration did not correlate with these data, nor did the symptomatic state correlate with the amount of amyloid in the biopsy specimens. The surface ultrastructure was normal when investigated by means of the scanning electron microscope in all patients except five in whom the glycocalyx was altered. As a group, however, those five did not differ in any respect from the rest of the patients. Rod-shaped microorganisms were shown to adhere to the surface in one patient. The results suggest that mechanisms other than bowel-wall deposition of amyloid cause the dysfunction of the gastrointestinal tract in familial amyloid polyneuropathy.

Adult↗
PubMed1986

[Who discovered Campylobacter jejuni/coli? A review of hitherto disregarded literature].

Non culturable spiral form bacteria were noted in 1886 by Theodor Escherich. He found them in stool specimens and large intestinal mucous associated with diarrhoea in neonates as well as in kittens. In the following years till the end of the century a number of mainly german language publications appeared, describing the occurrence of such "spirilla" in cases of "cholera-like" and "dysenteric" disease. These organisms were found mainly in the colon or associated with mucous in diarrheal stool specimens. Growth on solid medium was unsuccessful, although living bacteria could be kept in liquid culture medium for a few days. The following points suggest that the microorganisms described were probably Campylobacter ssp: typical morphology association with enteritis in neonates, infants and kittens failure to grow on solid medium despite microscopic detection and the fact that to date no other bacteria with comparable morphology have been associated with human enteric infections.

Animals↗
PubMed2000

[The mechanisms of antigen uptake in the small and large intestines: the roll of the M cells for the initiation of immune responses].

The gut-associated lymphoid tissues, e.g., the Peyer's patches and the appendix, constantly internalize antigenic material to rapidly generate an immune response, if necessary. This sampling of antigens is performed by specialized epithelial cells, the "membranous" or "microfold" (M) cells of the dome epithelia. M cells possess a unique ultrastructure and are typically in contact with lymphoid cells. They endocytose macromolecules and particles, including entire microorganisms, at their apical membrane, transport these in vesicles to their basolateral membrane, and exocytose them to the intercellular space. This article reviews the structural and functional characteristics of M cells in the digestive tract in humans and other species. Specializations of M cells for antigen uptake and transport comprise the composition of their apical membrane, a modified cytoskeleton as compared to enterocytes, and a large pocket-like invagination of the basolateral membrane populated by lymphocytes. Besides ultrastructural characteristics, histochemical markers are listed that are available for detecting M cells. The origin and differentiation pathways of M cells and enterocytes of the dome epithelium are outlined and critically commented on. Because M cells are known entry sites of various pathogens and, in the future, might be employed for the oral application of drugs and vaccines, the clinical relevance of M cells in health and disease is discussed.

Animals↗
PubMed2005

Hepcidin: a direct link between iron metabolism and immunity.

Hepcidin, originally discovered in urine as a bactericidal peptide synthesized by hepatocytes was later proved to be a key regulator of iron metabolism at the whole body level, namely, in conditions of altered iron demand such as the increased or decreased total amount of body iron, inflammation, hypoxia and anemia. The major mechanism of hepcidin function seems to be the regulation of transmembrane iron transport. Hepcidin binds to its receptor, protein ferroportin, which serves as a transmembrane iron channel enabling iron efflux from cells. The hepcidin-ferroportin complex is then degraded in lysosomes and iron is locked inside the cells (mainly enterocytes, hepatocytes and macrophages). This leads to lowering of iron absorption in the intestine and to a decrease in serum iron concentration. Utilizing this mechanism, hepcidin regulates serum iron levels during inflammation, infection and possibly also in cancer. Under these conditions iron is shifted from circulation into cellular stores in hepatocytes and macrophages, making it less available for invading microorganisms and tumor cells. In anemia and hypoxia, hepcidin regulates the availability of iron for erythropoiesis. Hepcidin or hepcidin-related therapeutics could find a place in the treatment of various diseases such as hemochromatosis and anemia of chronic disease.

Amino Acid Sequence↗
PubMed1976

Alterations in the fecal flora of an individual frequently lacking coliforms.

An individual who usually completely lacked or had very low numbers of coliforms in his stool over a period of 19 months was identified. The subject's levels of clostridia and aerobic lactobacilli were elevated as compared with those of our control group. However, these elevated populations of microorganisms were not related to the number of coliforms present in stool samples. The number of coliforms was inversely related to the number of anaerobic lactobacilli. In addition, the absence of coliforms was always accompanied by the absence of fungi. Populations of other prominent groups of intestinal flora were not significantly affected by the number of coliforms present in the intestnal tract. Since ankylosing spondylitis was the only physical abnormality of the subject, the intestinal flora of other individuals positive for histocompatibility antigen B27 who had this disease were examined but were found to be normal. The absence of coliforms from the normal flora of the intestinal tract of the subject had no apparent effect on his general health.

Adult↗