Antioxidative effects of lactic acid bacteria on the colonic mucosa of iron-overloaded mice

Ethnic foods: impact of probiotics on human health and disease treatment

The human gut is inhabited by approximately 100 trillion of microflora, and there exists a reciprocal relationship between human health and the gut microbiota. The major reasons for the dysbiosis in the population of gut microbiota are attributed to changes in lifestyle, medication, and the intake of junk foods. In addition, the proportion of beneficial bacteria in the intestine decreases gradually with age and causes physiological disturbances, malfunctions of the immune system, and several metabolic disorders. Thus, finding safe solutions to improve the diversity of microflora is a big challenge. With an increase in health consciousness among the population, the demand for healthy and nutraceutical food products is growing gradually. Recent research has proved that consumption of probiotics promotes gut health and prevents from several metabolic and other diseases. Hence, in this present review, we will discuss the various probiotic bacteria present in ethnic foods. The importance of these probiotics in the prevention and treatment of gastrointestinal, respiratory, cancer, and metabolic disorders will be elucidated. In addition, we will highlight the importance of the development of new-generation probiotics to cater the needs of the current market.

Calcium-rich dairy matrix protects better than mineral calcium against colonic luminal haem-induced alterations in male rats

The haemoglobin content in meat is consistently associated with an increased risk of colorectal cancer, whereas calcium may play a role as a chemopreventive agent. Using rodent models, calcium salts have been shown to prevent the promotion of haem-induced and red meat-induced colorectal carcinogenesis by limiting the bioavailability of the gut luminal haem iron. Therefore, this study aimed to compare impacts of dietary calcium provided as calcium salts or dairy matrix on gut homoeostasis perturbations by high haeminic or non-haeminic iron intakes. A 3-week intervention study was conducted using Fischer 344 rats. Compared to the ferric citrate-enriched diet, the haemoglobin-enriched diet led to increased faecal, mucosal, and urinary lipoperoxidation-related biomarkers, resulting from higher gut luminal haem iron bioavailability. This redox imbalance was associated to a dysbiosis of faecal microbiota. The addition of calcium to haemoglobin-enriched diets limited haem iron bioavailability and counteracted redox imbalance, with improved preventive efficacy when calcium was provided in dairy matrix. Data integration revealed correlations between haem-induced lipoperoxidation products and bacterial communities belonging to Peptococcaceae, Eubacterium coprostanoligenes group, and Bifidobacteriaceae. This integrated approach provides evidence of the benefits of dairy matrix as a dietary calcium vehicle to counteract the deleterious side-effects of meat consumption.

Orally administered Streptococcus thermophilus YIT 2001 is a vehicle for the delivery of glutathione, a reactive reduced thiol, to the intestine

AIMS

We aimed to analyze the behavior of cellular glutathione of Streptococcus thermophilus strain YIT 2001 (ST-1) in the gastrointestinal environment to understand how orally administered glutathione in ST-1 cells is delivered stably to the intestine in a reactive form, which is essential for its systemic bioavailability against lipid peroxidation.

METHODS AND RESULTS

Intracellular glutathione was labeled with L-cysteine-containing stable isotopes. ST-1 cells from fresh culture or lyophilized powder were treated with simulated gastric and intestinal juices for 60 min each. The release of intracellular glutathione in digestive juices was quantified via LC-MS/MS. Most of the cellular glutathione was retained in the gastric environment and released in response to exposure to the gastrointestinal environment. During digestion, the membrane permeability of propidium iodide increased significantly, especially when cells were exposed to cholate, without change in the cell wall state.

CONCLUSIONS

ST-1 cells act as vehicles to protect intracellular reactive components, such as glutathione, from digestive stress, and release them in the upper intestine owing to the disruption of membrane integrity induced by bile acid.

The effect of Lactobacillus fermentum DALI02 in reducing the oxidative stress and inflammatory response induced by high-fat diet of rats

A long-term high-fat diet (HFD) leads to significant oxidative stress in the body and induces inflammation. A preliminary evidence suggests a potential therapeutic utility of probiotics for this condition. To evaluate the potential effect of Lactobacillus fermentum DALI02 on the oxidative stress and inflammatory damage induced by HFD, we used a hyperlipidemic rat as a model fed with HFD. Results revealed that HFD induced a significant oxidative stress and inflammation. However, results reveal that L. fermentum DALI02, manifested a significant decrease in levels of malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and resistin, while the catalase (CAT), total antioxidant capability (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and adiponectin (ADPN) levels significantly increased. And it was dose-dependent that the effect of high dose groups with high viable count was particularly notable. The results suggest that L. fermentum DALI02 could alleviate oxidative stress and inflammation as it appeared to reduce lipid peroxidation and improved the lipid metabolism in vivo.

A long-term high-fat diet (HFD) leads to significant oxidative stress in the body and induces inflammation.

Isolation of lactic acid bacteria capable of reducing environmental alkyl and fatty acid hydroperoxides, and the effect of their oral administration on oxidative-stressed nematodes and rats

Reinforcement of the hydroperoxide-eliminating activity in the small and large intestines should prevent associated diseases. We previously isolated a lactic acid bacterium, Pediococcus pentosaceus Be1 that facilitates a 2-electron reduction of hydrogen peroxide to water. In this study, we successfully isolated an alternative lactic acid bacterium, Lactobacillus plantarum P1-2, that can efficiently reduce environmental alkyl hydroperoxides and fatty acid hydroperoxides to their corresponding hydroxyl derivatives through a 2-electron reduction. Each strain exhibited a wide concentration range with regard to the environmental reducing activity for each hydroperoxide. Given this, the two lactic acid bacteria were orally administered to an oxygen-sensitive short-lived nematode mutant, and this resulted in a significant expansion of its lifespan. This observation suggests that P. pentosaceus Be1 and L. plantarum P1-2 inhibit internal oxidative stress. To determine the specific organs involved in this response, we performed a similar experiment in rats, involving induced lipid peroxidation by iron-overloading. We observed that only L. plantarum P1-2 inhibited colonic mucosa lipid peroxidation in rats with induced oxidative stress.

Haem iron reshapes colonic luminal environment: impact on mucosal homeostasis and microbiome through aldehyde formation

BACKGROUND

The World Health Organization classified processed and red meat consumption as "carcinogenic" and "probably carcinogenic", respectively, to humans. Haem iron from meat plays a role in the promotion of colorectal cancer in rodent models, in association with enhanced luminal lipoperoxidation and subsequent formation of aldehydes. Here, we investigated the short-term effects of this haem-induced lipoperoxidation on mucosal and luminal gut homeostasis including microbiome in F344 male rats fed with a haem-enriched diet (1.5 μmol/g) 14-21 days.

RESULTS

Changes in permeability, inflammation, and genotoxicity observed in the mucosal colonic barrier correlated with luminal haem and lipoperoxidation markers. Trapping of luminal haem-induced aldehydes normalised cellular genotoxicity, permeability, and ROS formation on a colon epithelial cell line. Addition of calcium carbonate (2%) to the haem-enriched diet allowed the luminal haem to be trapped in vivo and counteracted these haem-induced physiological traits. Similar covariations of faecal metabolites and bacterial taxa according to haem-induced lipoperoxidation were identified.

CONCLUSIONS

This integrated approach provides an overview of haem-induced modulations of the main actors in the colonic barrier. All alterations were closely linked to haem-induced lipoperoxidation, which is associated with red meat-induced colorectal cancer risk.

Advances in Gut Microbiome Research, Opening New Strategies to Cope with a Western Lifestyle

The "westernization" of global eating and lifestyle habits is associated with the growing rate of chronic diseases, mainly cardiovascular diseases, cancer, type 2 diabetes mellitus, and respiratory diseases. The primary prevention approach is to make nutritional and behavioral changes, however, there is another important determinant of our health that only recently has been considered and is the presence of beneficial microorganisms and their products in our gastrointestinal tract. Microorganisms living in our body can alter the fate of food, drugs, hormones, and xenobiotics, and recent studies point to the use of microorganisms that can counteract the harmful effects of certain compounds introduced or produced endogenously in our body. This review considers the effects of the western lifestyle on adiposity, glucose metabolism, oxidative markers and inflammation profile, emphasizes on the studies that have investigated bacterial strains and products of their metabolism that are beneficial under this lifestyle, and examines the screening strategies that recent studies are using to select the most promising probiotic isolates. In addition, we consider the relevance of studying the microbiota of metabolically healthy people under a western lifestyle for the understanding of the key components that delay the development of chronic diseases.

Concomitant ingestion of lactic acid bacteria and black tea synergistically enhances flavonoid bioavailability and attenuates d-galactose-induced oxidative stress in mice via modulating glutathione antioxidant system

Black tea (BT) has been positively linked to improved redox status, while its efficacy is limited due to the low bioavailability of BT flavonoids. In addition to the direct antioxidant activity, flavonoids regulate redox balance via inducing endogenous antioxidants, particularly glutathione (GSH) and GSH-dependent antioxidant enzymes. This work first examined the effect of lactic acid bacteria (LAB) and BT alone or in combination on flavonoid bioavailability and metabolism; next, the effect of LAB-fermented BT diet in attenuating oxidative stress in mice and the underlying mechanisms were studied. Phenolic profiles of plasma, urine and feces from healthy mice consuming plain yogurt, BT milk (BTM) or BT yogurt (BTY) were acquired using LC-MS/MS. Plasma antioxidant capacity, lipid peroxidation level, content of nonprotein thiols and expression of GSH-related antioxidant enzymes and Nrf2 were examined in d-galactose-treated mice. Total flavonoid content in plasma following a single dose of BTY attained 0.657 μmol/l, increased by 50% compared with the BTM group. Increased excretion of phenolic metabolite and hippuric acid in urine and feces indicated enhanced metabolism of flavonoids in BTY-fed mice. In the second study, 8-week concomitant LAB-BT treatment of oxidatively stressed mice effectively restored plasma antioxidant capacity and GSH levels, and mitigated lipid peroxidation, which were associated with significant induction of GSH-dependent antioxidant enzymes and nuclear accumulation of Nrf2. Our results demonstrated the effect of LAB fermentation in enhancing BT flavonoid bioavailability in vivo. The synergistic antioxidant efficacy of LAB-BT diet implied its therapeutic potential in enhancing antioxidant defenses and protecting organisms from oxidative damage.

Effects of lactic acid bacteria on low-density lipoprotein susceptibility to oxidation and aortic fatty lesion formation in hyperlipidemic hamsters

We investigated the effects of Streptococcus thermophilus YIT 2001, a strain of lactic acid bacteria, on the susceptibility of low-density lipoprotein (LDL) to oxidation and the formation of aortic fatty lesions in hyperlipidemic hamsters. S. thermophilus YIT 2001 had the highest in vitro antioxidative activity against LDL oxidation among the 79 strains of lactic acid bacteria and bifidobacteria tested, which was about twice that of S. thermophilus YIT 2084. The lag time of LDL oxidation in the YIT 2001 feeding group was significantly longer than in controls, but was unchanged in the YIT 2084 group. After the feeding of YIT 2001, lag times were prolonged and areas of aortic fatty lesions were dose-dependently attenuated, although there were no effects on plasma lipid levels. These results suggest that YIT 2001 has the potential to prevent the formation of aortic fatty lesions by inhibiting LDL oxidation.

Antibiotic suppression of intestinal microbiota reduces heme-induced lipoperoxidation associated with colon carcinogenesis in rats

Epidemiological studies show that heme iron from red meat is associated with increased colorectal cancer risk. In carcinogen-induced-rats, a heme iron-rich diet increases the number of precancerous lesions and raises associated fecal biomarkers. Heme-induced lipoperoxidation measured by fecal thiobarbituric acid reagents (TBARs) could explain the promotion of colon carcinogenesis by heme. Using a factorial design we studied if microbiota could be involved in heme-induced carcinogenesis, by modulating peroxidation. Rats treated or not with an antibiotic cocktail were given a control or a hemoglobin-diet. Fecal bacteria were counted on agar and TBARs concentration assayed in fecal water. The suppression of microbiota by antibiotics was associated with a reduction of crypt height and proliferation and with a cecum enlargement, which are characteristics of germ-free rats. Rats given hemoglobin diets had increased fecal TBARs, which were suppressed by the antibiotic treatment. A duplicate experiment in rats given dietary hemin yielded similar results. These data show that the intestinal microbiota is involved in enhancement of lipoperoxidation by heme iron. We thus suggest that microbiota could play a role in the heme-induced promotion of colorectal carcinogenesis.

Effects of probiotic supplementation on systemic and intestinal oxidant-antioxidant events in splenectomized rats

PURPOSE

The objective of this study was to show the effects of probiotic supplementation on systemic and intestinal oxidant-antioxidant events in splenectomized rats.

METHODS

Male rats were divided into control (group 1) and splenectomized (group 2) groups, and after splenectomy, some rats were given Lactobacillus delbruckii subsp. bulgaricus (highest amount of extracellular polysaccharides, 211 mg/l) for 7 days (group 3) or were given the treatment for 7 days before and 7 days after splenectomy (group 4). The plasma and small intestine tissue thiobarbituric acid reactive substances (TBARS), sulfhydryl group, glutathione, ascorbic acid, and nitric oxide metabolites (NO x ) levels were determined by a spectrophotometer.

RESULTS

We found increased TBARS levels in both the plasma and small intestine in the splenectomized rats compared to controls. L. delbruckii subsp. bulgaricus supplementation decreased the TBARS levels in the plasma in the splenectomized rats. In this study, the plasma TBARS and NO x levels were decreased by L. delbruckii subsp. bulgaricus supplementation after or both after and before splenectomy (groups 3 and 4).

CONCLUSIONS

Together, these data suggest that. L. delbruckii subsp. bulgaricus supplementation is beneficial for decreasing lipid peroxidation and enhancing the antioxidant capacity of systemic and intestinal tissue in splenectomized rats.

Amelioration of colitis in mouse model by exploring antioxidative potentials of an indigenous probiotic strain of Lactobacillus fermentum Lf1

Based on the preliminary screening of eight indigenous putative probiotic Lactobacilli, Lactobacillus fermentum Lf1 was selected for assessing its antioxidative efficacy in DSS colitis mouse model based on its ability to enhance the expression of “Nrf2” by 6.43-fold and malondialdehyde (MDA) inhibition by 78.1  ±  0.24% in HT-29 cells under H₂O₂ stress. The Disease Activity Index and histological scores of Lf1-treated mice were lower than the control group. However, expression of “Nrf2” was not observed in Lf1-treated mice. A significant increase in the expression of antioxidative enzymes such as SOD2 and TrxR-1 was recorded in both of the groups. The expression of SOD2 was significantly downregulated in colitis-induced mice by −100.00-fold relative to control group, and the downregulation was considerably reduced to −37.04-fold in colitis Lf1 treatment group. Almost, a similar trend was recorded in case of “thioredoxin” expression, though “CAT” was refractile to expression. The Lf1-treated group had decreased malondialdehyde level as compared to colitis control (37.92  ±  6.31 versus 91.13  ±  5.76 μM/g). These results point towards Lf1-induced activation of the antioxidant enzyme system in the mouse model and its prospects to be explored as a new strategy for IBD management.

Lactobacillus plantarum ZLP001: In vitro Assessment of Antioxidant Capacity and Effect on Growth Performance and Antioxidant Status in Weaning Piglets

The objective of this study was to evaluate the antioxidant capacity of Lactobacillus plantarum ZLP001 and its effects on growth performance and antioxidant status in weaning piglets. The survival in hydrogen peroxide and free radical-scavenging activity of Lactobacillus plantarum ZLP001 were analysed in vitro. The Lactobacillus plantarum ZLP001 showed high viability in 1.0 mmol/L hydrogen peroxide and high scavenging ability against hydroxyl, superoxide anion, and DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals which was dose dependent. Ninety-six weaning piglets were selected (7.45±0.79 kg) and divided into three groups comprising of negative control without any supplementation, treatment group with supplemented 6.8×10(7) Lactobacillus plantarum ZLP001 CFU/g of diet, and positive control with antibiotic treatment (chlorotetracycline, 80 mg/kg diet). The results showed that Lactobacillus plantarum ZLP001 supplementation enhanced feed conversion rates in piglets compared with control (p<0.05). Supplementation of Lactobacillus plantarum ZLP001 increased the concentration of superoxide dismutase (p<0.05), glutathione peroxidase (p<0.01) and catalase in serum (p<0.10), while decreased the concentration of malondialdehyde (p<0.05). The present study implies that the strain Lactobacillus plantarum ZLP001 had high antioxidant ability and its supplementation improved the growth performance and antioxidant status of weaning piglets, so it can be considered useful to alleviate oxidative stress and increase productive performance of pigs. (Key Words: Probiotic, Antioxidant Capacity, Weaning Piglet).

Klebsiella pneumoniae increases the risk of inflammation and colitis in a murine model of intestinal bowel disease

OBJECTIVE

Intrarectal treatment with 2,4,6-trinitrobenzene sulfonic acid (TNBS), an inducer of intestinal inflammation, in mice increases the population size of Enterobacteriaceae, particularly Klebsiella pneumoniae, while reducing the population size of lactic acid bacteria. Therefore, we investigated the effects of these bacteria in TNBS-induced colitis in mice.

MATERIAL AND METHODS

Colitis was induced in vivo by rectal administration of TNBS in male Institute of Cancer Research mice. Inflammatory markers were determined by enzyme-linked immunosorbent assay and immunoblot analysis.

RESULTS

Oral administration of K. pneumoniae increased COX-2, IL-1β, IL-6 and TNF-α expression, NF-κB activation, and lipid peroxidation in the colon, but reduced tight junction-associated proteins, claudin-1, ZO-1 and occludin. K. pneumoniae also deteriorated the expression of inflammatory markers and tight junction-associated proteins in TNBS-induced colitic mice. K. pneumoniae produced β-glucuronidase and lipopolysaccharide, which potently induced NO and COX-2 production in murine peritoneal macrophages. However, oral administration of Lactobacillus johnsonii, which is isolated from the feces of mice, inhibited TNBS-induced colon shortening, the reduction of tight junction-associated proteins, expression of inflammatory markers, and lipid peroxidation. These findings suggest that the disturbance of intestinal bacterial composition, and in particular the irregular increase of K. pneumoniae in the colon, may cause colitis.

The effect of exopolysaccharide-producing probiotic strains on gut oxidative damage in experimental colitis

BACKGROUND

Oxidative stress plays a role in disease initiation and progression in inflammatory bowel disease (IBD) and manipulation of this pathway may attenuate disease progress. In this study, the effect of exopolysaccharide (EPS)-producing probiotic bacteria on gut oxidative damage was evaluated in a rat model of experimental colitis.

METHODS

Colitis was induced by intracolonic administration of acetic acid. Rats were treated daily with two probiotic strains, L. delbrueckii subsp. bulgaricus B3 strain (EPS of 211 mg/l; high-EPS group) or L. delbrueckii subsp. bulgaricus A13 strain (EPS of 27 mg/l; low-EPS group), which were given directly into the stomach. Non-colitis-fed control and preventative groups were only treated with the high-EPS producing strain. Antioxidant enzyme activities (superoxide dismutase, catalase, total glutathione, reduced glutathione, glutathione disulfide) and lipid peroxidation were measured in colonic tissue samples after a treatment period of 7 days.

RESULTS

Significant oxidative damage was associated with a higher level of malondialdehyde (MDA) activity and reduced antioxidant enzyme activities in the colitis model group. All antioxidant enzyme activities were higher in both probiotic-treated groups compared with those of the colitis model group (P < 0.001). Lipid peroxidation was significantly ameliorated in both probiotic groups. The improvement of oxidative stress parameters was significantly more in the high-EPS group than in the low-EPS group (P < 0.001).

CONCLUSIONS

EPS-producing probiotic bacteria significantly attenuate oxidative stress in experimental colitis. Increased EPS production gives rise to a better probiotic function. These results suggest that EPS molecules could revaluate probiotic strains and exert their beneficial effects on the host and this may have a therapeutic potential.

The effect of selected microbial strains on internal milieu of broiler chickens after peroral administration

The aim of this work was to investigate the effect of probiotic preparation with multi-strains composition (Lactobacillus delbrueckii ssp. bulgaricus LAT 187, Lactobacillus acidophilus LAT 180, Lactobacillus helveticus LAT 179, Lactobacillus delbrueckii ssp. lactis LAT 182, Streptococcus thermophilus LAT 205 and Enterococcus faecium E 253) on internal milieu, antioxidant status and body weight of broiler chickens. Chickens were divided into three groups (C, control; E1 and E2, experimental groups). Experimental chickens received the probiotic preparation in drinking water. Probiotic preparation caused a significant increase of serum calcium and potassium content. In the group with higher dose of probiotic strains serum triglycerides level decreased. Total antioxidant status in groups with addition of probiotic strains showed higher values in comparison to control group. Serum albumin level was found to increase after consumption of probiotic preparation in group with higher dose of probiotic strains. Probiotic strains improved body weight in last observed weeks of feeding.

Dextran sulfate sodium and 2,4,6-trinitrobenzene sulfonic acid induce lipid peroxidation by the proliferation of intestinal gram-negative bacteria in mice

ABSTRECT:

BACKGROUND

To understand whether TLR-4-linked NF-kB activation negatively correlates with lipid peroxidation in colitic animal models, we caused colitis by the treatment with dextran sulfate sodium (DSS) or 2,4,6-trinitrobenzenesulfonic acid (TNBS) to C3H/HeJ (TLR-4-defective) and C3H/HeN (wild type) mice, investigated inflammatory markers, lipid peroxidation, proinflammatory cytokines and TLR-4-linked NF-kappaB activation, in colon and intestinal bacterial composition in vivo.

METHODS

Orally administered DSS and intrarectally injected TNBS all caused severe inflammation, manifested by shortened colons in both mice. These agents increased intestinal myeloperoxidase activity and the expression of the proinflammatory cytokines, IL-1beta, TNF-alpha and IL-6, in the colon.

RESULTS

DSS and TNBS induced the protein expression of TLR-4 and activated transcription factor NF-kappaB. However, these colitic agents did not express TLR-4 in C3H/HeJ mice. Of proinflammatory cytokines, IL-1beta was most potently expressed in C3H/HeN mice. IL-1beta potently induced NF-kappaB activation in CaCo-2 cells, but did not induce TLR-4 expression. DSS and TNBS increased lipid peroxide (malondialdehyde) and 4-hydroxy-2-nonenal content in the colon, but reduced glutathione content and superoxide dismutase and catalase activities. These colitic inducers increased the number of Enterobacteriaceae grown in DHL agar plates in both mice, although the number of anaerobes and bifidobacteria grown in GAM and BL agar plates was reduced. E. coli, K. pneumoniae and Proteus mirabilis isolated in DHL agar plates increased lipid peroxidation in liposomes prepared by L-alpha-phosphatidylcholine, but B. animalis and B. cholerium isolated from BL agar plates inhibited it.

DISCUSSION

These findings suggest that DSS and TNBS may cause colitis by inducing lipid peroxidation and enterobacterial proliferation, which may deteriorate the colitis by regulating proinflammatory cytokines via TLR-4-linked NF-kappaB activation pathway.

Lactobacilli prevent hydroxy radical production and inhibit Escherichia coli and Enterococcus growth in system mimicking colon fermentation

AIMS

To explore the effect of Lactobacillus on redox state of colon chyme.

METHODS AND RESULTS

Nine Lactobacillus strains were studied for the inhibition of lipid peroxide formation in Fe(2+)/ascorbate system and for their ability to chelate 'free' ferrous ion. The result shows both properties were strain specific and no relationship between them was found. Both properties of Lactobacillus paracasei Fn032, Lactobacillus rhamnosus GG (LGG) and Lactobacillus sp. Fn001 were successively decreasing. LGG and Fn032 significantly decreased hydroxyl radicals (P < 0.01) in colonic fermentation model, in which considerable hydroxyl radicals occurred spontaneously. Addition of ferrous ion induced the production of hydroxyl radicals, which could be significantly inhibited by LGG, Fn032 (P < 0.01) and Fn001 (P < 0.05). Ferrous ion significantly induced the growth of Enterococcus and Escherichia coli, which could be inhibited by all three Lactobacillus strains. Escherichia coli and Enterococcus show significantly positive correlation with hydroxyl radicals with R of 0.96 (P = 0.0002) and 0.91 (P = 0.0017), respectively.

CONCLUSIONS

Antioxidative Lactobacillus could modulate redox state in colonic fermentation system, which is related to their free radical-scavenging ability or antibacterial effect.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study proves that Lactobacillus strain could influence the redox state of gut chyme. Evaluation of antioxidative ability might be a powerful method for screening probiotic Lactobacillus strains.

Differential effects of Bifidobacterium pseudolongum strain Patronus and metronidazole in the rat gut

In the luminal contents of metronidazole-treated rats, there was a dominant Bifidobacterium species. A strain has been isolated, its 16S rRNA gene has been sequenced, and the strain has been named Bifidobacterium pseudolongum strain Patronus. In this study, using an experimental model of healthy rats, the effects of metronidazole treatment and B. pseudolongum strain Patronus administration on the luminal and mucosa-associated microbiota and on gut oxidation processes were investigated. Metronidazole treatment and the daily gavage of rats with B. pseudolongum strain Patronus increased the numbers of bifidobacteria in cecal contents and in cecal mucosa-associated microbiota compared with those in control rats. Metronidazole reduced the colonic oxidative damage to proteins. This is the first evidence that B. pseudolongum strain Patronus exerts an effect on a biomarker of oxidative damage by reducing the susceptibility to oxidation of proteins in the colon and the small bowel. Antioxidant effects of metronidazole could be linked to the bifidobacterial increase but also to other bacterial modifications.

Preventive effect of Streptococcus thermophilus YIT 2001 on dextran sulfate sodium-induced colitis in mice

We investigated the preventive effect of Streptococcus thermophilus YIT 2001, a lactic acid bacterum having high antioxidative activity, on acute colitis induced by 2.5% dextran sulfate sodium in mice, and compared the effect with that of S. thermophilus YIT 2084 which has lower antioxidative activity. Feeding S. thermophilus YIT 2001 decreased the disease activity index and level of lipid peroxide (the thiobarbituric acid reactive substance content) in the colonic mucosa. The hematocrit and hemoglobin concentrations in the blood of S. thermophilus YIT 2001-fed mice were higher than those of the control mice. S. thermophilus YIT 2084 had no significant effect on these parameters. The results suggest that the antioxidative activity of S. thermophilus YIT 2001 was involved in the improving effect on colitis.

Effect of probiotics, Bifidobacterium breve and Lactobacillus casei, on bisphenol A exposure in rats

Bisphenol A (BPA), a putative endocrine disruptor, may be taken up by humans via the diet and have adverse effects on human health. In this study, we evaluated whether the probiotics, Bifidobacterium breve strain Yakult (BbY) and Lactobacillus casei strain Shirota (LcS), could exert a protective effect against dietary exposure to BPA. A group of rats fed on a diet containing 5% BbY or 5% LcS showed three advantageous effects compared to the control group; (i) the area under the blood concentration-time curve of BPA after its oral administration was significantly decreased, (ii) the amount of BPA excreted in the feces was significantly greater (2.4 times), and (iii) the percentage of BPA bound to the sediment fraction of the feces was significantly higher. These results suggest that BbY and LcS reduced the intestinal absorption by facilitating the excretion of BPA, and that these probiotics may suppress the adverse effects of BPA on human health.

Iron metabolism in infants and children

Meeting the iron requirements of infants and children is difficult, and supplementation or fortification of food with iron is often recommended. Although iron supplementation of infants and children with iron deficiency and iron-deficiency anemia may be beneficial, recent studies suggest that this may not be the case for those with adequate iron status, and adverse effects have been noted. The recent discoveries of proteins and peptides regulating iron absorption have enhanced our knowledge of iron metabolism in infants and children. Iron is taken up in the small intestine by divalent metal transporter-1 and is either stored by ferritin inside the mucosal cell or transported to the systemic circulation by ferroportin, while being oxidized by hephaestin to be incorporated into transferrin. Hepcidin, a small peptide synthesized by the liver, can sense iron stores and regulates iron transport by inhibition of ferroportin. However, regulation of iron transporters is immature in infants, possibly explaining the adverse effects of iron supplementation. Interactions among iron, vitamin A, zinc, and copper need to be considered when evaluating the effects of iron supplementation on infants and children.

A probiotic strain of Bacillus polyfermenticus reduces DMH induced precancerous lesions in F344 male rat

Bacillus polyfermenticus has been used in an effective treatment for long-term intestinal disorders, as live strains in the form of active endospores have been shown to reach the target intestine successfully. In this study, we have assessed the effects of B. polyfermenticus on the antioxidant system and the process of colon carcinogenesis in male F344 rats. The rats were divided into three groups after a 1-week adaptation period, and were then fed on either a high-fat and low-fiber diet (control and DMH groups), or a high-fat and low-fiber diet supplemented with B. polyfermenticus (3.1x10(8) cfu/d) (DMH+B. polyfermenticus group). One week after beginning the diets, the rats were subjected to 6 weeks of treatment with 1,2-dimethylhydrazine (DMH, 30 mg/kg/week, s.c.). The dietary treatments continued over the entirety of the experimental period. Nine weeks after the initial DMH injection, the rats supplemented with B. polyfermenticus evidenced significantly lower numbers of aberrant crypt foci than were observed in the DMH group. Injections with DMH resulted in significantly higher leukocytic DNA damage and plasma lipid peroxidation levels, as well as a lower plasma total antioxidant potential, and these factors recovered as the result of supplementation with B. polyfermenticus. These data indicate that B. polyfermenticus exerts a protective effect on the antioxidant system and the process of colon carcinogenesis, thereby suppressing the development of preneoplastic lesions.

Prebiotics, probiotics, and synbiotics affect mineral absorption, bone mineral content, and bone structure

Several studies in animals and humans have shown positive effects of nondigestible oligosaccharides (NDO) on mineral absorption and metabolism and bone composition and architecture. These include inulin, oligofructose, fructooligosaccharides, galactooligosaccharides, soybean oligosaccharide, and also resistant starches, sugar alcohols, and difructose anhydride. A positive outcome of dietary prebiotics is promoted by a high dietary calcium content up to a threshold level and an optimum amount and composition of supplemented prebiotics. There might be an optimum composition of fructooligosaccharides with different chain lengths (synergy products). The efficacy of dietary prebiotics depends on chronological age, physiological age, menopausal status, and calcium absorption capacity. There is evidence for an independent probiotic effect on facilitating mineral absorption. Synbiotics, i.e., a combination of probiotics and prebiotics, can induce additional effects. Whether a low content of habitual NDO would augment the effect of dietary prebiotics or synbiotics remains to be studied. The underlying mechanisms are manifold: increased solubility of minerals because of increased bacterial production of short-chain fatty acids, which is promoted by the greater supply of substrate; an enlargement of the absorption surface by promoting proliferation of enterocytes mediated by bacterial fermentation products, predominantly lactate and butyrate; increased expression of calcium-binding proteins; improvement of gut health; degradation of mineral complexing phytic acid; release of bone-modulating factors such as phytoestrogens from foods; stabilization of the intestinal flora and ecology, also in the presence of antibiotics; stabilization of the intestinal mucus; and impact of modulating growth factors such as polyamines. In conclusion, prebiotics are the most promising but also best investigated substances with respect to a bone-health-promoting potential, compared with probiotics and synbiotics. The results are more prominent in animal models, where more studies have been performed, than in human studies, where experimental conditions are more difficult to control.

Non-haem iron transport in the rat proximal colon

BACKGROUND

Only 10% of dietary iron is absorbed in the duodenum which implies that 90% (approximately 9 mg day(-1)) reaches the lower small intestine and colon. Therefore the purpose of this study was to assess the iron transport capacity of the rat proximal colon and to determine whether iron absorption is regulated by changes in dietary iron content.

MATERIALS AND METHODS

Rats were fed for 14 days on either iron adequate (44 mg Fe kg(-1) diet) or iron-deficient (< 0.5 mg Fe kg(-1) diet) diets. The 59Fe transport across the colonic epithelium and its subsequent appearance in the blood were measured in vivo. In separate studies the colon was excised and used to measure divalent metal transporter expression.

RESULTS

Divalent metal transporter (DMT1) was expressed at the apical membrane of the surface epithelium in rat proximal colon. In animals fed an iron-deficient diet, DMT1 mRNA and protein expression were increased. This was accompanied by a significant increase in tissue 59Fe uptake.

CONCLUSIONS

The proximal colon can absorb non-haem iron from the intestinal lumen. The purpose of this mechanism remains to be elucidated.