Probiotics and zinc in acute infectious gastroenteritis in children: are they effective?

Interplay between Candida albicans and Lactic Acid Bacteria in the Gastrointestinal Tract: Impact on Colonization Resistance, Microbial Carriage, Opportunistic Infection, and Host Immunity

Emerging studies have highlighted the disproportionate role of Candida albicans in influencing both early community assembly of the bacterial microbiome and dysbiosis during allergic diseases and intestinal inflammation. Nonpathogenic colonization of the human gastrointestinal (GI) tract by C. albicans is common, and the role of this single fungal species in modulating bacterial community reassembly after broad-spectrum antibiotics can be readily recapitulated in mouse studies. One of the most notable features of C. albicans-associated dysbiotic states is a marked change in the levels of lactic acid bacteria (LAB). C. albicans and LAB share metabolic niches throughout the GI tract, and in vitro studies have identified various interactions between these microbes. The two predominant LAB affected are Lactobacillus species and Enterococcus species. Lactobacilli can antagonize enterococci and C. albicans, while Enterococcus faecalis and C. albicans have been reported to exhibit a mutualistic relationship. E. faecalis and C. albicans are also causative agents of a variety of life-threatening infections, are frequently isolated together from mixed-species infections, and share certain similarities in clinical presentation-most notably their emergence as opportunistic pathogens following disruption of the microbiota. In this review, we discuss and model the mechanisms used by Lactobacillus species, E. faecalis, and C. albicans to modulate each other's growth and virulence in the GI tract. With multidrug-resistant E. faecalis and C. albicans strains becoming increasingly common in hospital settings, examining the interplay between these three microbes may provide novel insights for enhancing the efficacy of existing antimicrobial therapies.

Gut Microbiota as a Mediator of Essential and Toxic Effects of Zinc in the Intestines and Other Tissues

The objective of the present study was to review the existing data on the association between Zn status and characteristics of gut microbiota in various organisms and the potential role of Zn-induced microbiota in modulating systemic effects. The existing data demonstrate a tight relationship between Zn metabolism and gut microbiota as demonstrated in Zn deficiency, supplementation, and toxicity studies. Generally, Zn was found to be a significant factor for gut bacteria biodiversity. The effects of physiological and nutritional Zn doses also result in improved gut wall integrity, thus contributing to reduced translocation of bacteria and gut microbiome metabolites into the systemic circulation. In contrast, Zn overexposure induced substantial alterations in gut microbiota. In parallel with intestinal effects, systemic effects of Zn-induced gut microbiota modulation may include systemic inflammation and acute pancreatitis, autism spectrum disorder and attention deficit hyperactivity disorder, as well as fetal alcohol syndrome and obesity. In view of both Zn and gut microbiota, as well as their interaction in the regulation of the physiological functions of the host organism, addressing these targets through the use of Zn-enriched probiotics may be considered an effective strategy for health management.

The different effects of probiotics treatment on Salmonella-induced interleukin-8 response in intestinal epithelia cells via PI3K/Akt and NOD2 expression

Salmonella spp. remains a major public health problem for the whole world. Intestinal epithelial cells serve as an essential component of the innate mucosal immune system to defend against Salmonella infection. A substantial amount of evidence has accumulated that probiotics can regulate interleukin 8 (IL-8) involved in innate immunity. However, the exact effect of probiotics on epithelial IL-8 response to Salmonella infection is not well understood. Therefore, we investigated the action of probiotics on Salmonella-infected Caco-2 cells and its novel mechanisms. Two probiotic strains were examined for Salmonella-induced IL-8 responses and regulating proteins using Caco-2 cell cultures. We demonstrated probiotic, either Lactobacillus rhamnosus GG or Bifidobacterium animalis subsp. lactis DSM10140, administered before Salmonella infection conferred significantly suppressive effect on Salmonella-induced IL-8 responses in Caco-2 cells, either in secreted protein or mRNA, via the PI3K/Akt signal pathway while probiotic administered after infection enhanced Salmonella-induced IL-8 responses via nucleotide-binding oligomerisation domain-containing protein 2 expression in membrane. These findings suggest that the different regulation of probiotics on Salmonella-induced IL-8 responses in Caco-2 cells according to the administered timing supports a rationale for the therapeutic use of probiotics in the treatment of Salmonella colitis and inflammatory bowel disease. This can explain the reported controversial effect of probiotics on these diseases.

A double blind randomized trial showing probiotics to be ineffective in acute diarrhea in Indonesian children

OBJECTIVE

To investigate the efficacy of probiotics added to oral rehydration solution and zinc in the treatment of acute infectious diarrhea in Indonesian children.

METHODS

A prospective randomized double blind placebo-controlled trial was performed to test the efficacy of a probiotic food supplement in 112 children in the Kenari subdistrict, central Jakarta, aged 6-36 mo with acute infectious diarrhea and moderate dehydration. The supplemented group was given standard therapy (oral rehydration solution and zinc) and the probiotic strains Lactobacillus (L.) rhamnosus R0011 1.9 × 10(9) colony forming units (cfu) and L. acidophilus R0052 0.1 × 10(9) cfu/d for 7 d, while the control group was given standard therapy and placebo.

RESULTS

Median duration of diarrhea was 68.5 h (range 13-165) in the supplemented and 61.5 h (range 21-166) in the control group (P = 0.596). Median daily frequency of defecation until diarrhea stopped was 5.0 in the supplemented vs. 5.5 in the control group (P = 0.795).

CONCLUSIONS

This probiotic food supplement tested did not reduce the duration of acute infectious diarrhea as compared to oral rehydration and zinc.

Efficacy of probiotic use in acute rotavirus diarrhea in children: A systematic review and meta-analysis

BACKGROUND

Probiotic therapies with different strains demonstrated some beneficial effects, although some studies did not show any significant effects. This study assessed systematically the current knowledge on the effect of probiotic bacteria on duration of acute rotavirus diarrhea in children compared with control.

METHODS

The PubMed, Cochrane Controlled Trial Register (CCTR) and Ovid (Wolters Kluwer Health) were searched between 1980 to June 15, 2013. Randomized controlled trials including the administration of probiotics for treatment of rotavirus diarrhea in infants and children were reviewed.

RESULTS

A total number of 1244 articles were found through the aforementioned search. 203 articles were selected after the first screening of title and abstract. The intervention group included subjects who received probiotic strains and dosage in any conditions. Placebo or any similar vehicle without probiotic was used in the controlled trials. Finally, 14 articles were selected. The outcomes from each study were considered in the duration of diarrhea. Statistical analyses were performed with Stata software. The pooled estimate of efficacy of probiotics in prevention or treatment of disease yielded in all studies a mean difference of 0.41 (CI 95%: -0.56 to -0.25; p<0.001). The pooled estimate of efficacy of lactobacillus rhamnosus GG and other probiotics significantly reduced the duration of diarrhea. Among trials, the overall reduction of LGG was 0.47 (CI 95%: -0.80 to -0.14; P= 0.020).

CONCLUSION

In conclusion, probiotics exert positive effect in reducing the duration of acute rotavirus diarrhea compared with control.

Lactic acid bacteria contribution to gut microbiota complexity: lights and shadows

Lactic Acid Bacteria (LAB) are ancient organisms that cannot biosynthesize functional cytochromes, and cannot get ATP from respiration. Besides sugar fermentation, they evolved electrogenic decarboxylations and ATP-forming deiminations. The right balance between sugar fermentation and decarboxylation/deimination ensures buffered environments thus enabling LAB to survive in human gastric trait and colonize gut. A complex molecular cross-talk between LAB and host exists. LAB moonlight proteins are made in response to gut stimuli and promote bacterial adhesion to mucosa and stimulate immune cells. Similarly, when LAB are present, human enterocytes activate specific gene expression of specific genes only. Furthermore, LAB antagonistic relationships with other microorganisms constitute the basis for their anti-infective role. Histamine and tyramine are LAB bioactive catabolites that act on the CNS, causing hypertension and allergies. Nevertheless, some LAB biosynthesize both gamma-amino-butyrate (GABA), that has relaxing effect on gut smooth muscles, and beta-phenylethylamine, that controls satiety and mood. Since LAB have reduced amino acid biosynthetic abilities, they developed a sophisticated proteolytic system, that is also involved in antihypertensive and opiod peptide generation from milk proteins. Short-chain fatty acids are glycolytic and phosphoketolase end-products, regulating epithelial cell proliferation and differentiation. Nevertheless, they constitute a supplementary energy source for the host, causing weight gain. Human metabolism can also be affected by anabolic LAB products such as conjugated linoleic acids (CLA). Some CLA isomers reduce cancer cell viability and ameliorate insulin resistance, while others lower the HDL/LDL ratio and modify eicosanoid production, with detrimental health effects. A further appreciated LAB feature is the ability to fix selenium into seleno-cysteine. Thus, opening interesting perspectives for their utilization as antioxidant nutraceutical vectors.

Dose-response effect of Bifidobacterium lactis HN019 on whole gut transit time and functional gastrointestinal symptoms in adults

OBJECTIVE

To assess the impact of Bifidobacterium lactis HN019 supplementation on whole gut transit time (WGTT) and frequency of functional gastrointestinal (GI) symptoms in adults.

MATERIAL AND METHODS

We randomized 100 subjects (mean age: 44 years; 64% female) with functional GI symptoms to consume a proprietary probiotic strain, B. lactis HN019 (Fonterra Research Centre, Palmerston North, New Zealand), at daily doses of 17.2 billion colony forming units (CFU) (high dose; n = 33), 1.8 billion CFU (low dose; n = 33), or placebo (n = 34) for 14 days. The primary endpoint of WGTT was assessed by X-ray on days 0 and 14 and was preceded by consumption of radiopaque markers once a day for 6 days. The secondary endpoint of functional GI symptom frequency was recorded with a subject-reported numeric (1-100) scale before and after supplementation.

RESULTS

Decreases in mean WGTT over the 14-day study period were statistically significant in the high dose group (49 ± 30 to 21 ± 32 h, p < 0.001) and the low dose group (60 ± 33 to 41 ± 39 h, p = 0.01), but not in the placebo group (43 ± 31 to 44 ± 33 h). Time to excretion of all ingested markers was significantly shorter in the treatment groups versus placebo. Of the nine functional GI symptoms investigated, eight significantly decreased in frequency in the high dose group and seven decreased with low dose, while two decreased in the placebo group. No adverse events were reported in any group.

CONCLUSIONS

Daily B. lactis HN019 supplementation is well tolerated, decreases WGTT in a dose-dependent manner, and reduces the frequency of functional GI symptoms in adults.

What zinc supplementation does and does not achieve in diarrhea prevention: a systematic review and meta-analysis

BACKGROUND

Prevention of diarrhea has presented indomitable challenges. A preventive strategy that has received significant interest is zinc supplementation. Existing literature including quantitative meta-analyses and systematic reviews tend to show that zinc supplementation is beneficial however evidence to the contrary is augmenting. We therefore conducted an updated and comprehensive meta-analytical synthesis of the existing literature on the effect of zinc supplementation in prevention of diarrhea.

METHODS

EMBASE®, MEDLINE ® and CINAHL® databases were searched for published reviews and meta-analyses on the use of zinc supplementation for the prevention childhood diarrhea. Additional RCTs published following the meta-analyses were also sought. Effect of zinc supplementation on the following five outcomes was studied: incidence of diarrhea, prevalence of diarrhea, incidence of persistent diarrhea, incidence of dysentery and incidence of mortality. The published RCTs were combined using random-effects meta-analyses, subgroup meta-analyses, meta-regression, cumulative meta-analyses and restricted meta-analyses to quantify and characterize the role of zinc supplementation with the afore stated outcomes.

RESULTS

We found that zinc supplementation has a modest beneficial association (9% reduction) with incidence of diarrhea, a stronger beneficial association (19% reduction) with prevalence of diarrhea and occurrence of multiple diarrheal episodes (28% reduction) but there was significant unexplained heterogeneity across the studies for these associations. Age, continent of study origin, zinc salt and risk of bias contributed significantly to between studies heterogeneity. Zinc supplementation did not show statistically significant benefit in reducing the incidence of persistent diarrhea, dysentery or mortality. In most instances, the 95% prediction intervals for summary relative risk estimates straddled unity.

CONCLUSIONS

Demonstrable benefit of preventive zinc supplementation was observed against two of the five diarrhea-related outcomes but the prediction intervals straddled unity. Thus the evidence for a preventive benefit of zinc against diarrhea is inconclusive. Continued efforts are needed to better understand the sources of heterogeneity. The outcomes of zinc supplementation may be improved by identifying subgroups that need zinc supplementation.

Proteomics as a tool for studying energy metabolism in lactic acid bacteria

Lactic acid bacteria (LAB) are very ancient organisms that can't obtain metabolic energy by respiration without external heme supplementation. Since the gain in ATP from lactic fermentation is inadequate to support efficient growth, they developed alternative strategies for energy production. Three main energy generating routes are present in LAB: amino acid decarboxylation, malate decarboxylation and arginine deimination (ADI pathway). These routes, apart from supplying energy, also play a role in pH control. Lactic fermentation, which leads to lactic acid accumulation, causes a pH decrease that amino acid decarboxylations, originating basic amines, and the ADI pathway, giving rise to ammonia, may partially contrast. In the present mini-review, the reciprocal relationships among these metabolic pathways are considered, on the basis of proteomic results obtained from four different LAB strains, all of which possess the ADI pathway, but express different amino acid decarboxylases. The strains have been isolated and selected from different habitats and the role of some inducing molecules as well as of the growth phases is discussed. The overall results have revealed that LAB are complex biosystems able to set up a sophisticated metabolic regulation through a complex network of proteins that also include stress responses, as well as protease activation or inhibition.

Therapeutic value of zinc supplementation in acute and persistent diarrhea: a systematic review

BACKGROUND

For over a decade, the importance of zinc in the treatment of acute and persistent diarrhea has been recognized. In spite of recently published reviews, there remain several unanswered questions about the role of zinc supplementation in childhood diarrhea in the developing countries. Our study aimed to assess the therapeutic benefits of zinc supplementation in the treatment of acute or persistent diarrhea in children, and to examine the causes of any heterogeneity of response to zinc supplementation.

METHODS AND FINDINGS

EMBASE, MEDLINE and CINAHL databases were searched for published reviews and meta-analyses on the use of zinc supplementation for the prevention and treatment of childhood diarrhea. Additional RCTs published following the meta-analyses were also sought. The reviews and published RCTs were qualitatively mapped followed by updated random-effects meta-analyses, subgroup meta-analyses and meta-regression to quantify and characterize the role of zinc supplementation with diarrhea-related outcomes. We found that although there was evidence to support the use of zinc to treat diarrhea in children, there was significant unexplained heterogeneity across the studies for the effect of zinc supplementation in reducing important diarrhea outcomes. Zinc supplementation reduced the mean duration of diarrhea by 19.7% but had no effect on stool frequency or stool output, and increased the risk of vomiting. Our subgroup meta-analyses and meta-regression showed that age, stunting, breast-feeding and baseline zinc levels could not explain the heterogeneity associated with differential reduction in the mean diarrheal duration. However, the baseline zinc levels may not be representative of the existing zinc deficiency state.

CONCLUSIONS

Understanding the predictors of zinc efficacy including the role of diarrheal disease etiology on the response to zinc would help to identify the populations most likely to benefit from supplementation. To improve the programmatic use of zinc, further evaluations of the zinc salts used, the dose, the frequency and duration of supplementation, and its acceptability are required. The significant heterogeneity of responses to zinc suggests the need to revisit the strategy of universal zinc supplementation in the treatment children with acute diarrhea in developing countries.

Improved ability of biological and previous caries multimarkers to predict caries disease as revealed by multivariate PLS modelling

BACKGROUND

Dental caries is a chronic disease with plaque bacteria, diet and saliva modifying disease activity. Here we have used the PLS method to evaluate a multiplicity of such biological variables (n = 88) for ability to predict caries in a cross-sectional (baseline caries) and prospective (2-year caries development) setting.

METHODS

Multivariate PLS modelling was used to associate the many biological variables with caries recorded in thirty 14-year-old children by measuring the numbers of incipient and manifest caries lesions at all surfaces.

RESULTS

A wide but shallow gliding scale of one fifth caries promoting or protecting, and four fifths non-influential, variables occurred. The influential markers behaved in the order of plaque bacteria > diet > saliva, with previously known plaque bacteria/diet markers and a set of new protective diet markers. A differential variable patterning appeared for new versus progressing lesions. The influential biological multimarkers (n = 18) predicted baseline caries better (ROC area 0.96) than five markers (0.92) and a single lactobacilli marker (0.7) with sensitivity/specificity of 1.87, 1.78 and 1.13 at 1/3 of the subjects diagnosed sick, respectively. Moreover, biological multimarkers (n = 18) explained 2-year caries increment slightly better than reported before but predicted it poorly (ROC area 0.76). By contrast, multimarkers based on previous caries predicted alone (ROC area 0.88), or together with biological multimarkers (0.94), increment well with a sensitivity/specificity of 1.74 at 1/3 of the subjects diagnosed sick.

CONCLUSION

Multimarkers behave better than single-to-five markers but future multimarker strategies will require systematic searches for improved saliva and plaque bacteria markers.

Colon in acute intestinal infection

The colon is actively implicated in intestinal infections not only as a target of enteric pathogens and their products but also as a target organ for treatment. In the presence of diarrhea, both of osmotic and secretory nature, the colon reacts with homeostatic mechanisms to increase ion absorption. These mechanisms can be effectively exploited to decrease fluid discharge. A model of intestinal infections using rotavirus (RV) in colonic cells was set up and used to define a dual model of secretory and osmotic diarrhea in sequence. Using this model, antidiarrheal drugs were tested, namely zinc and the enkephalinase inhibitor racecadotril. Zinc was able to decrease the enterotoxic activity responsible for secretory diarrhea. It also inhibited the cytotoxic effect of RV. The mechanism of zinc was related at least in part to the activation of MAPK activity, but also a direct antiviral effect was observed. Racecadotril showed a potent and selective inhibition of active secretion, being particularly effective in the first phase of RV diarrhea. The use of drugs active at the colonic level, therefore, offers effective options to treat intestinal infections in childhood. In addition, the colon is the natural site of colonic microflora, a target of probiotic therapy, which is the first line of approach recommended by the European Society for Paediatric Gastroenterology, Hepatology and Nutrition to treat infectious diarrhea.

Enteric infection meets intestinal function: how bacterial pathogens cause diarrhoea

Infectious diarrhoea is a significant contributor to morbidity and mortality worldwide. In bacterium-induced diarrhoea, rapid loss of fluids and electrolytes results from inhibition of the normal absorptive function of the intestine as well as the activation of secretory processes. Advances in the past 10 years in the fields of gastrointestinal physiology, innate immunity and enteric bacterial virulence mechanisms highlight the multifactorial nature of infectious diarrhoea. This review explores the various mechanisms that contribute to loss of fluids and electrolytes following bacterial infections, and attempts to link these events to specific virulence factors and toxins.

Saccharomyces boulardii prevents oral-poliovirus vaccine-induced IgA nephropathy in mice

Immunoglobulin A nephropathy (IgAN) is associated with mucosal IgA defect. Probiotics regulate specific and innate immunity. We evaluated the effect of Saccharomyces boulardii on experimental IgAN in mice. Four groups of BALB/c mice (eight for each) were formed. Group 1 was immunized by oral poliovirus vaccine (OPV) at 0, 14, and 28 days. Group 2 was also given S. boulardii in addition to OPV. Group 3 was given only S. boulardii, whereas group 4 received no treatment. At week 6, after urine and serum samples were obtained for urinalysis and serum creatinine and IgA measurements, all animals were sacrificed to get their kidneys for histopathological evaluation. Urinalysis and serum creatinine levels were normal in all groups. Serum IgA level was increased only in group 1. Whereas group 1 had mesangial proliferation, histology was normal in the other groups. Predominant IgA deposition was universal in group 1, whereas it was either not present or minimal in other groups. Three mice in group 1 also had C3 deposition, which was absent in other groups. Electron microscopy revealed mesangial proliferation, matrix expansion, focal glomerular basement membrane thickening and electron-dense deposits in group 1 only, whereas the other groups were normal. In conclusion, enteral S. boulardii prevented OPV-induced IgAN in mice.

Chronic enteropathy and feeding in children: an update

Enteropathy defines abnormalities of the small intestinal mucosa of various etiologies in which nutrition has a causal or a therapeutic role. Breast milk is the gold-standard feeding during infancy for optimal nutrition in health and the majority of diseases. Therapeutic formulae have decreased the need for enteral or parenteral support. Gastrointestinal infections are worldwide the most frequent cause of enteropathy by increasing mucosal permeability, local expression of costimulatory molecules allowing antigen penetration in the mucosa, and T-cell activation leading sometimes to disruption of oral tolerance. Concomitant malnutrition impairs not only the immunologic response but also the recovery of damaged mucosa with secondary intestinal and pancreatic enzymatic reductions. Optimal nutritional rehabilitation is the cornerstone of the management of persisting diarrhea. Celiac disease and cow's milk protein allergy are examples of chronic enteropathy. Multiple food allergies, even during breast-feeding, are increasingly reported due to an impaired development of oral tolerance. The dietary approach to allergic disease is currently evolving from passive allergen avoidance to active modulation of the immune system to (re)establish tolerance. The gastrointestinal flora provides maturational signals for the lymphoid tissue, improves balance of inflammatory cytokines, reduces bacterial invasiveness and dietary antigen load, and normalizes gut permeability. The clinical effects of nucleotides and zinc merit further clinical evaluation. Major attention has recently focused on the immune effects of dietary lipids in terms of possible prevention of allergic sensitization by downregulating inflammatory response and protecting the epithelial barrier and host-microbe interactions modifying the adherence of microbes to the mucosa.