Inhibition of binding of the AB5-type enterotoxins LT-I and cholera toxin to ganglioside GM1 by galactose-rich dietary components

A Scoping Review on the Therapeutic Potential of Resin From the Species Larix decidua Mill. [Pinaceae] to Treat Ulcerating Wounds

Malignant ulcerating wounds or neoplastic lesions are a considerable burden for patients suffering from advanced cancer. These wounds have no effective treatment and are very difficult to manage. The present review summarizes evidence in support of a hypothesis put forward in anthroposophic medicine, which suggests a beneficial role of resin from the species Larix decidua Mill. [Pinaceae] for treating such wounds. A systematic search strategy was performed using the databases PubMed, EMBASE and SciFinder. The included publications described the chemical composition of this species, as well as in vitro, in vivo, and ex vivo experiments using plant extracts and isolated compounds. The results show that among the phytochemical classes, terpenoids were the major components of this species, especially in the resin. The summarized biological experiments revealed antimicrobial, antioxidant and anti-inflammatory effects, with promising potential for the extracts and isolated compounds. However, the molecular mechanisms and toxicological effects are as of yet not conclusively evaluated. From the data of our study, we can conclude that L. decidua might indeed have a promising potential for the treatment of malignant wounds, but definitive information that can prove its effectiveness is still lacking. We therefore suggest that future efforts should be dedicated to the evaluation of L. decidua resin's therapeutic use considering its antiseptic action and proposed wound healing properties.

The roles of mesoporous silica and carbon nanoparticles in antigen stability and intensity of immune response against recombinant subunit B of cholera toxin in a rabbit animal model

Vaccines are the front line in the fight against diseases. However, setbacks with existing cholera vaccines have ignited a considerable effort to develop more suitable vaccine formulations. In this study, we aim to investigate the effect of antigen stability and controlled release in inducing an immune response. Therefore, two types of silica and carbon mesoporous nanoparticles of the same size and shape but different pore architectures were synthesized and loaded with recombinant cholera toxin subunit B to serve as a model for antigen stability and controlled release of antigenic CTB. In order to evaluate immune response efficacy for these model formulations, IgG and IgA responses and fluid accumulation (FA) index were measured in immunized rabbits, which were challenged with wild-type Vibrio cholerae. Our result suggests that mesoporous silica nanoparticles have greater efficacy in inducing mucosal immune responses, and it proved more proficiency in overall immune responses in challenge experiments and FA index (p < 0.05). These findings indicate that mesoporous nanoparticles and, in particular, mesoporous silica nanoparticles, could be used in oral vaccine formulation against cholera.

The anti-diarrhea activity of red algae-originated sulphated polysaccharides on ETEC-K88 infected mice

Polysaccharides from red algae Porphyra haitanensis and Gracilaria lemaneiformis possess various bioactive functions, however, their anti-diarrhea activity remains incompletely defined. In the current study, sulphated polysaccharides were extracted by high pressure treatment plus ethanol precipitation from these two algae, and named PHSP_(hp) and GLSP_(hp), respectively. PHSP_(hp) and GLSP_(hp) showed decreased viscosity and molecular weight. Meanwhile, they have a certain immunomodulatory effect on wound healing and migration of RAW264.7 cells. Moreover, they significantly increased the secretion of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). A BALB/c model infected by enterotoxigenic Escherichia coli (ETEC)-K88 was also established to evaluate the anti-diarrhea activity of PHSP_(hp) and GLSP_(hp). The results showed that PHSP_(hp) and GLSP_(hp) were able to alleviate mice diarrhea symptoms. Meanwhile, they inhibited the release of pro-inflammatory cytokines and suppressed the secretion of immunoglobulin A via reducing the population of B cells. In addition, the nitroblue tetrazolium levels of mouse serum were decreased. Taken together, PHSP_(hp) and GLSP_(hp) alleviated the inflammatory response of ETEC-K88-induced diarrhea through both specific and non-specific immunity. Sulphated polysaccharides from red algae may be used as functional food components for remitting diarrhea.

Polysaccharides from red algae Porphyra haitanensis and Gracilaria lemaneiformis possess various bioactive functions, however, their anti-diarrhea activity remains incompletely defined.

Effects of fenugreek (Trigonella foenum-graecumL.) seed extract supplementation in different energy density diets on growth performance, nutrient digestibility, blood characteristics, fecal microbiota, and fecal gas emission in growing pigs

This study evaluated the efficacy of fenugreek seed extract (FSE) in growing pigs. About 140 growing pigs [(Yorkshire × Landrace) × Duroc] with an average body weight (BW) of 23.70 ± 2.80 kg were used in a 6 wk trial. Treatments were (on as-fed basis) two levels of FSE (FSE0, 0 or FSE0.2, 2 g kg−1basal diet), and two levels of energy [low-energy diet (LED); 3160 or high-energy diet (HED); 3260 kcal kg−1metabolizable energy (ME)]. Pigs in HED and FSE0.2 diets had higher final BW, average daily gain, and gain:feed ratio (G:F) compared with in LED, and FSE0 diets, respectively (P < 0.05). Pigs fed the FSE0.2 and HED diets had higher energy (E) digestibility than the FSE0 and LED diets, respectively (P < 0.05). Pigs fed the FSE0.2 diet increased serum immunoglobulin G (IgG), and reduced total cholesterol (TC) concentration than the FSE0 diet (P < 0.05). Hydrogen sulfide (H2S) and ammonia (NH3) gas emission in FSE0.2 diet were lower than that in FSE0 group (P < 0.05). In conclusion, results indicated that dietary supplementation of FSE improved growth performance, digestibility, serum IgG, reduced serum TC, and noxious gas emission in growing pigs.

Fucosylated Molecules Competitively Interfere with Cholera Toxin Binding to Host Cells

Cholera toxin (CT) enters host intestinal epithelia cells, and its retrograde transport to the cytosol results in the massive loss of fluids and electrolytes associated with severe dehydration. To initiate this intoxication process, the B subunit of CT (CTB) first binds to a cell surface receptor displayed on the apical surface of the intestinal epithelia. While the monosialoganglioside GM1 is widely accepted to be the sole receptor for CT, intestinal epithelial cell lines also utilize fucosylated glycan epitopes on glycoproteins to facilitate cell surface binding and endocytic uptake of the toxin. Further, l-fucose can competively inhibit CTB binding to intestinal epithelia cells. Here, we use competition binding assays with l-fucose analogs to decipher the molecular determinants for l-fucose inhibition of cholera toxin subunit B (CTB) binding. Additionally, we find that mono- and difucosylated oligosaccharides are more potent inhibitors than l-fucose alone, with the LeY tetrasaccharide emerging as the most potent inhibitor of CTB binding to two colonic epithelial cell lines (T84 and Colo205). Finally, a non-natural fucose-containing polymer inhibits CTB binding two orders of magnitude more potently than the LeY glycan when tested against Colo205 cells. This same polymer also inhibits CTB binding to T84 cells and primary human jejunal epithelial cells in a dose-dependent manner. These findings suggest the possibility that polymeric display of fucose might be exploited as a prophylactic or therapeutic approach to block the action of CT toward the human intestinal epithelium.

GM1 ganglioside-independent intoxication by Cholera toxin

Cholera toxin (CT) enters and intoxicates host cells after binding cell surface receptors via its B subunit (CTB). We have recently shown that in addition to the previously described binding partner ganglioside GM1, CTB binds to fucosylated proteins. Using flow cytometric analysis of primary human jejunal epithelial cells and granulocytes, we now show that CTB binding correlates with expression of the fucosylated Lewis X (LeX) glycan. This binding is competitively blocked by fucosylated oligosaccharides and fucose-binding lectins. CTB binds the LeX glycan in vitro when this moiety is linked to proteins but not to ceramides, and this binding can be blocked by mAb to LeX. Inhibition of glycosphingolipid synthesis or sialylation in GM1-deficient C6 rat glioma cells results in sensitization to CT-mediated intoxication. Finally, CT gavage produces an intact diarrheal response in knockout mice lacking GM1 even after additional reduction of glycosphingolipids. Hence our results show that CT can induce toxicity in the absence of GM1 and support a role for host glycoproteins in CT intoxication. These findings open up new avenues for therapies to block CT action and for design of detoxified enterotoxin-based adjuvants.

Engineering a short-chain dehydrogenase/reductase for the stereoselective production of (2S,3R,4S)-4-hydroxyisoleucine with three asymmetric centers

Fenugreek is a dietary supplement for anti-aging and human health. (2S,3R,4S)-4-hydroxyisoleucine (4-HIL), which is extracted from fenugreek seeds, is expected to be a promising orally active drug for diabetes and diabetic nephropathy because of its insulinotropic effect. Although several chemical synthesis methods of 4-HIL have been proposed, these methods require multistep reactions to control the stereochemistry of 4-HIL. In this study, we modified the key enzyme 4-HIL dehydrogenase (HILDH) to overcome the biggest limitation in commercial-scale production of 4-HIL. As a result, an effective one-step carbonyl reduction to produce (2S,3R,4S)-4-HIL was successfully accomplished with strict stereoselectivity (>99% de). Mass production of (2S,3R,4S)-4-HIL by our synthetic method could have a significant contribution to the prevention of diabetes, dyslipidemia, and Alzheimer's disease. (120 words/200 words).

Dietary fenugreek seed extract improves performance and reduces fecal E. coli counts and fecal gas emission in lactating sows and suckling piglets

Hossain, M. M., Begum, M., Nyachoti, C. M., Hancock, J. D. and Kim, I. H. 2015. Dietary fenugreek seed extract improves performance and reduces fecal E. coli counts and fecal gas emission in lactating sows and suckling piglets. Can. J. Anim. Sci. 95: 561–568. This study evaluated the efficacy of fenugreek seed extract (FSE) in sows and suckling piglets. The trial was conducted with 78 multiparous sows and their litters in a 28-d feeding trial, and one of three diets: CON (control, basal diet); FSE1 (basal diet+0.1% FSE), and FSE2 (basal diet+0.2% FSE). Piglets suckling sows fed the FSE1 and FSE2 diets had higher average daily gain compared with those suckling sows fed the CON from week 2 to weaning (linear, P<0.05). At weaning, sows fed the FSE1 and FSE2 diets had higher immunoglobulin G and lower low-density lipoprotein–cholesterol concentrations compared with those fed the CON diet (linear, P<0.05). Sows fed the FSE2 diet linearly reduced total cholesterol concentrations at weaning (P<0.05). Piglets suckling sows fed the FSE2 diet had higher immunoglobulin G and red blood cell concentrations compared with those suckling sows fed the CON diet (linear, P<0.05). Sows fed the FSE2 diet had higher apparent total tract digestibility of N and gross energy and reduced fecal E. coli counts and ammonia gas emission compared with those fed the CON diet at weaning (linear, P<0.05). In conclusion, results indicate that feeding sows a diet supplemented with FSE in late gestation and lactation improved performance in sows and suckling piglets.

Antibacterial and antidiarrheal activities of plant products against enterotoxinogenic Escherichia coli

Enterotoxigenic Escherichia coli (ETEC) produces two types of enterotoxins: heat-labile (LT) and heat-stable (STa and STb). These molecules are involved in the induction of secretory diarrhea in animals including humans. This condition is currently treated using a fluid replacement therapy and antibiotics. This treatment is often not available to people in developing countries, and several die from the condition provoke by ETEC. Over the years, plants and plant extracts have been use as traditional medicine to treat various gastrointestinal ailments including diarrhea. Many of these plant products have been claimed to be active against diarrhea, however few have been extensively studied. The main objective of this review was to gather the scattered information on the antidiarrheal activities reported for various plant products on ETEC. This includes two major effects: (1) The inhibitory effect on bacterial growth or viability and (2) The interference with ETEC enterotoxins activity upon the intestinal epithelium. We will focus on plant products and extracts for which we have major indications of their biological activity against ETEC and their enterotoxins. Because Vibrio cholerae toxin (CT) is structurally, antigenically and mechanistically related to LT, it will also be discussed in this review.

Review of the inhibition of biological activities of food-related selected toxins by natural compounds

There is a need to develop food-compatible conditions to alter the structures of fungal, bacterial, and plant toxins, thus transforming toxins to nontoxic molecules. The term 'chemical genetics' has been used to describe this approach. This overview attempts to survey and consolidate the widely scattered literature on the inhibition by natural compounds and plant extracts of the biological (toxicological) activity of the following food-related toxins: aflatoxin B1, fumonisins, and ochratoxin A produced by fungi; cholera toxin produced by Vibrio cholerae bacteria; Shiga toxins produced by E. coli bacteria; staphylococcal enterotoxins produced by Staphylococcus aureus bacteria; ricin produced by seeds of the castor plant Ricinus communis; and the glycoalkaloid α-chaconine synthesized in potato tubers and leaves. The reduction of biological activity has been achieved by one or more of the following approaches: inhibition of the release of the toxin into the environment, especially food; an alteration of the structural integrity of the toxin molecules; changes in the optimum microenvironment, especially pH, for toxin activity; and protection against adverse effects of the toxins in cells, animals, and humans (chemoprevention). The results show that food-compatible and safe compounds with anti-toxin properties can be used to reduce the toxic potential of these toxins. Practical applications and research needs are suggested that may further facilitate reducing the toxic burden of the diet. Researchers are challenged to (a) apply the available methods without adversely affecting the nutritional quality, safety, and sensory attributes of animal feed and human food and (b) educate food producers and processors and the public about available approaches to mitigating the undesirable effects of natural toxins that may present in the diet.

In vitro inhibition of ETEC K88 adhesion by pea hulls and of LT enterotoxin binding by faba bean hulls

Enterotoxigenic Escherichia coli (ETEC) expressing K88 (F4) adhesins are associated with post-weaning diarrhoea in piglets. Different grain fractions from pea (Pisum sativum) and faba bean (Vicia faba) were tested in vitro for their capacity to counteract aetiological factors, which contribute to the development of diarrhoea. In detail, adhesion of E. coli O149:K91:K88ac (ETEC K88ac) to grain legume products, intended to impair the colonization of the host, was studied as well as interference with receptor binding of the pathogen's heat-labile enterotoxin LT, intended to reduce toxin-inflicted gut cell damage. When comparing different pea and faba bean products tested for their binding capacity of ETEC K88ac, especially pea hulls, but also whole pea meal, starch-enriched and protein-enriched pea meal, and digestion-resistant pea hull and meal fractions showed a higher binding of ETEC K88ac than faba bean products. In contrast to the ETEC K88ac adhesion results, bean hulls proved more effective than pea hulls in preventing GM1 receptor binding of LT. Previous small intestinal segment perfusion experiments we performed with ETEC K88ac-challenged piglets indicated that both pea and bean hulls have the potential for successful application in diarrhoea prophylaxis and treatment, which is in agreement with and refined by our detection of their different modes of functioning.

Fenugreek seed affects intestinal microbiota and immunological variables in piglets after weaning

Fenugreek seed has been shown to affect the intestinal microbiota and immunological responses in animals. A feeding trial with male castrated piglets was performed over 28 d without or with the addition of 1·5 g fenugreek seeds/kg complete diet in ten and eleven piglets, weaned at 21 d. In the intestinal tract, pH, lactate and SCFA were measured as major bacterial metabolites. Immune cell phenotypes, phagocytic activity and lymphocyte proliferation after stimulation with pokeweed mitogen, concanavalin A and phytohaemagglutinin M were measured by flow cytometry. Health status and performance of the piglets were not affected by fenugreek. The pH in the caecum and colon were reduced compared with the control (P< 0·05). Higher concentrations of l-lactic acid were recorded in the small-intestinal digesta (average concentrations from the duodenum, jejunum and ileum; P< 0·05), while the concentrations of SCFA remained unchanged except an increase in n-butyric acid in colon contents (P< 0·05). The piglets fed the fenugreek diet had higher Lactobacillus and clostridium cluster I concentrations and lower Escherichia, Hafnia and Shigella concentrations in the small intestine. The addition of fenugreek increased the relative concentration of the γδ T-cell population (TCR1+CD8α-) in the blood with a simultaneous reduction of antigen-presenting cells (MHCII+CD5-) (P< 0·05). Proliferation rate and phagocytosis activity of monocytes were not affected by the additive. In conclusion, fenugreek seeds might be interesting as a feed ingredient for young piglets due to their effects on the intestinal microbiota and immunological variables. The impact on performance and animal health has to be further evaluated.