Probiotics and the mechanism of necrotizing enterocolitis

Bench to bedside - new insights into the pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death and disability from gastrointestinal disease in premature infants. Recent discoveries have shed light on a unifying theorem to explain the pathogenesis of NEC, suggesting that specific treatments might finally be forthcoming. A variety of experiments have highlighted how the interaction between bacterial signalling receptors on the premature intestine and an abnormal gut microbiota incites a pro-inflammatory response in the intestinal mucosa and its underlying endothelium that leads to NEC. Central amongst the bacterial signalling receptors implicated in NEC development is the lipopolysaccharide receptor Toll-like receptor 4 (TLR4), which is expressed at higher levels in the premature gut than in the full-term gut. The high prenatal intestinal expression of TLR4 reflects the role of TLR4 in the regulation of normal gut development, and supports additional studies indicating that NEC develops in response to signalling events that occur in utero. This Review provides new evidence explaining the pathogenesis of NEC, explores new findings indicating that NEC development has origins before birth, and discusses future questions and opportunities for discovery in this field.

Preventive Effect of Bifidobacterium Supplementation on Neonatal Cholestasis in Preterm Neonates with Very Low Birth Weight

Background

Cholestasis is a common but serious clinical condition in preterm neonates. The current management for preterm neonatal cholestasis has limitations. The aim of this study was to determine effects of Bifidobacterium supplementation on the prevention and alleviation of cholestasis in preterm infants with very low birth weight.

Methods

Preterm neonates with very low birth weight were enrolled in the Children's Hospital of Soochow University between December 2012 and December 2017. The patients were randomly assigned into Bifidobacterium and control groups, and effects of Bifidobacterium supplementation on the outcomes were compared between the two groups.

Results

There was no significant difference in the baseline characteristics in the two groups. Notably, the proportion of cases with neonatal cholestasis was significantly lower, with fewer neonatal cholestasis-associated complications in the Bifidobacterium group compared with the control group (6% versus 22%, P < 0.01). Furthermore, the Bifidobacterium group exhibited less severe cholestasis and better improvement of the liver function than the control group as evidenced by the biochemical tests (P < 0.01). Furthermore, the Bifidobacterium group exhibited less severe cholestasis and better improvement of the liver function than the control group as evidenced by the biochemical tests (P < 0.01). Furthermore, the Bifidobacterium group exhibited less severe cholestasis and better improvement of the liver function than the control group as evidenced by the biochemical tests (days, P < 0.01). Furthermore, the Bifidobacterium group exhibited less severe cholestasis and better improvement of the liver function than the control group as evidenced by the biochemical tests (P < 0.01). Furthermore, the Bifidobacterium group exhibited less severe cholestasis and better improvement of the liver function than the control group as evidenced by the biochemical tests (P < 0.01). Furthermore, the Bifidobacterium group exhibited less severe cholestasis and better improvement of the liver function than the control group as evidenced by the biochemical tests (P < 0.01). Furthermore, the Bifidobacterium group exhibited less severe cholestasis and better improvement of the liver function than the control group as evidenced by the biochemical tests (P < 0.01). Furthermore, the Bifidobacterium group exhibited less severe cholestasis and better improvement of the liver function than the control group as evidenced by the biochemical tests (

Conclusions

Bifidobacterium supplementation has significantly preventive and other beneficial effects on the management of cholestasis in preterm infants with very low birth weight. Its long-term safety and effectiveness will need further investigation. This trial is registered with the Chinese Clinical Trial Registry (Registration No. ChiCTR1900022296).

[Protective effect of Lactobacillus reuteri against oxidative stress in neonatal mice with necrotizing enterocolitis]

OBJECTIVE

To investigate the protective effect of L. reuteri DSM17938 strain against oxidative stress in a neonatal mouse model of necrotizing enterocolitis (NEC) and explore the possible mechanism.

METHODS

Ninety-six 10-day-old neonatal C57BL/6J mice were equally randomized into control group, NEC group, and NEC+ L. reuteri group. The pathological changes of the ileocecal intestinal tissue were evaluated with HE staining and double-blind pathological scoring. The mRNA and protein expressions of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the intestinal tissues were detected using quantitative real-time PCR and ELISA, respectively. Colorimetric assays were used to determine the activity of superoxide dismutase (SOD) and its inhibition rate, malondialdehyde (MDA), glutathione (GSH), oxidized glutathione (GSSG), and GSSG/ GSH ratio.

RESULTS

Compared with those in the control group, the neonatal mice in NEC group showed significant weight loss (P < 0.05), obvious intestinal injury, increased pathological scores (P < 0.05), increased expressions of TNF-α and IL-1β mRNA and proteins (P < 0.05), decreased SOD activity and inhibition rate, decreased GSH, and significantly increased MDA, GSSG, and GSSG/GSH ratios (P < 0.05). Treatment with L. reuteri obviously decreased the pathological scores, expressions of TNF-α and IL-1β (P < 0.05), MDA, GSSG, and GSSG/GSH ratio (P < 0.05), and significantly increased SOD activity, its inhibition rate, and GSH level in the mice with NEC, but the survival rate was not significantly different between NEC and L. reuteri-treated groups (P > 0.05).

CONCLUSIONS

L. reuteri DSM17938 can offer protection against NEC in mice by reducing oxidative stress and increasing antioxidant capacity of the intestinal tissue to suppress intestinal inflammations.

Functional Role of Probiotics and Prebiotics on Skin Health and Disease

Scientific and commercial interest of probiotics, prebiotics and their effect on human health and disease has increased in the last decade. The aim of this review article is to evaluate the role of pro- and prebiotics on the normal function of healthy skin as well as their role in the prevention and therapy of skin disease. Lactobacilli and Bifidobacterium are the most commonly used probiotics and thought to mediate skin inflammation, treat atopic dermatitis (AD) and prevent allergic contact dermatitis (ACD). Probiotics are shown to decolonise skin pathogens (e.g., P. aeruginosa, S. aureus, A. Vulgaris, etc.) while kefir is also shown to support the immunity of the skin and treat skin pathogens through the production of antimicrobial substances and prebiotics. Finally, prebiotics (e.g., Fructo-oligosaccharides, galacto-oligosaccharides and konjac glucomannan hydrolysates) can contribute to the treatment of diseases including ACD, acne and photo aging primarily by enhancing the growth of probiotics.

Necrotizing enterocolitis: Current concepts in practice

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in preterm infants and continues to be a major cause of morbidity and mortality. The incidence of NEC as well as mortality from the disease has persisted at unacceptably high levels for decades as current understanding of the cause remains incomplete. Identifying infants at risk and preventing NEC are mainstays of care. This article briefly examines disease presentation and treatment, identifies gaps in current understanding of disease pathology, and highlights new research that may lead to a decrease in the incidence of NEC in the future.

Astragaloside IV ameliorates necrotizing enterocolitis by attenuating oxidative stress and suppressing inflammation via the vitamin D3-upregulated protein 1/NF-κB signaling pathway

Astragaloside IV (AS-IV) is a flavonoid from the plant Astragalus membranaceus (Fisch) Bge that has a wide range of therapeutic effects. The aim of the present study was to examine the effect of AS-IV on rats with necrotizing enterocolitis (NEC) under oxidative stress and inflammation. Newborn Sprague-Dawley rats were induced with NEC by asphyxia and hypothermia applied on 3 consecutive days. The rats were orally administered AS-IV at 25, 50 and 75 mg/kg for 4 days. The results revealed that AS-IV administration prevented NEC-induced decrease in the concentration of malondialdehyde and myeloperoxidase, and increase in the activity of glutathione (GSH) and superoxide dismutase in murine models. AS-IV also inhibited NEC-induced elevation in the levels of interleukin (IL)-6, IL-1β, tumor necrosis factor-α and nuclear factor (NF)-κB. The effects of AS-IV were achieved under inflammation and oxidative stress. Western blotting demonstrated that AS-IV substantially inhibited the phosphorylated (p)-IκBα, NF-κBp65, p-NF-κBp65 protein levels and increased vitamin D3 upregulated protein 1 (VDUP1) and IκBα protein levels. These data indicate that AS-IV may be effective in the protection of NEC-induced ileum degeneration by inhibiting the levels of inflammatory markers and oxidative stress via the regulation of the VDUP1/NF-κB signaling pathway.

Harvesting the benefits of biofilms: A novel probiotic delivery system for the prevention of necrotizing enterocolitis

BACKGROUND/PURPOSE

Probiotics reduce the incidence of necrotizing enterocolitis (NEC) albeit only when administered at high frequency (at least daily). We have developed a novel probiotic delivery system in which probiotics are grown as a biofilm on microspheres, allowing enhanced efficacy with only a single treatment.

METHODS

Neonatal rats were subjected to experimental NEC. Pups received a single enteral dose of: (1) vehicle only, (2) unloaded microspheres, (3) MRS (broth)-loaded microspheres, (4) Lactobacillus reuteri, (5) L. reuteri grown on unloaded microspheres, or (6) L. reuteri grown on MRS-loaded microspheres. Intestinal injury was graded histologically and intestinal permeability determined by serum levels of enterally administered fluorescein isothiocyanate-labeled dextran.

RESULTS

69% of untreated pups developed NEC, whereas 32% of pups treated with L. reuteri grown as a biofilm on unloaded microspheres (p=0.009) and 33% of pups treated with L. reuteri grown as a biofilm on MRS-loaded microspheres (p=0.005) developed NEC. No other group had a significant reduction in NEC. Furthermore, pups treated with L. reuteri grown as a biofilm had significantly reduced intestinal permeability.

CONCLUSIONS

A single dose of Lactobacillus biofilm grown on biocompatible microspheres significantly reduces NEC incidence and severity. This novel probiotic delivery system may be beneficial in the prevention of NEC in the future.

Pathogenesis of neonatal necrotizing enterocolitis

Although necrotizing enterocolitis (NEC) is the most lethal gastrointestinal disease in the neonatal population, its pathogenesis is poorly understood. Risk factors include prematurity, bacterial colonization, and formula feeding. This review examines how mucosal injury permits opportunistic pathogens to breach the gut barrier and incite an inflammatory response that leads to sustained overproduction of mediators such as nitric oxide and its potent adduct, peroxynitrite. These mediators not only exacerbate the initial mucosal injury, but they also suppress the intestinal repair mechanisms, which further compromises the gut barrier and culminates in bacterial translocation, sepsis, and full-blown NEC.

Autoinducer-2 plays a crucial role in gut colonization and probiotic functionality of Bifidobacterium breve UCC2003

In the present study we show that luxS of Bifidobacterium breve UCC2003 is involved in the production of the interspecies signaling molecule autoinducer-2 (AI-2), and that this gene is essential for gastrointestinal colonization of a murine host, while it is also involved in providing protection against Salmonella infection in Caenorhabditis elegans. We demonstrate that a B. breve luxS-insertion mutant is significantly more susceptible to iron chelators than the WT strain and that this sensitivity can be partially reverted in the presence of the AI-2 precursor DPD. Furthermore, we show that several genes of an iron starvation-induced gene cluster, which are downregulated in the luxS-insertion mutant and which encodes a presumed iron-uptake system, are transcriptionally upregulated under in vivo conditions. Mutation of two genes of this cluster in B. breve UCC2003 renders the derived mutant strains sensitive to iron chelators while deficient in their ability to confer gut pathogen protection to Salmonella-infected nematodes. Since a functional luxS gene is present in all tested members of the genus Bifidobacterium, we conclude that bifidobacteria operate a LuxS-mediated system for gut colonization and pathogen protection that is correlated with iron acquisition.