Inflammatory bowel disease, a dysregulated host-microbiota interaction: are probiotics a new therapeutic option?

Inflammatory Bowel Disease: A focus on the Role of Probiotics in Ulcerative Colitis

Inflammatory bowel disease (IBD) is a cluster of disorders of the gastrointestinal tract characterized by chronic inflammation and imbalance of the gut microbiota in a genetically vulnerable host. Crohn’s disease and ulcerative colitis (UC) are well-known types of IBD, and due to its high prevalence, IBD has attracted the attention of researchers globally. The exact etiology of IBD is still unknown; however, various theories have been proposed to provide some explanatory clues that include gene-environment interactions and dysregulated immune response to the intestinal microbiota. These diseases are manifested by several clinical symptoms that depend on the affected segment of the intestine such as diarrhea, abdominal pain, and rectal bleeding. In this era of personalized medicine, various options are developing starting from improved intestinal microecology, small molecules, exosome therapy, to lastly stem cell transplantation. From another aspect, and in parallel to pharmacological intervention, nutrition, and dietary support have shown effectiveness in IBD management. There is an increasing evidence supporting the benefit of probiotics in the prophylaxis and treatment of IBD. There are several studies that have demonstrated that different probiotics alleviate UC. The present review summarizes the progress in the IBD studies focusing and exploring more on the role of probiotics as a potential adjunct approach in UC management.

Effects of Pretreatment with Bifidobacterium bifidum Using 16S Ribosomal RNA Gene Sequencing in a Mouse Model of Acute Colitis Induced by Dextran Sulfate Sodium

Background

Bifidobacterium is a potentially effective and safe treatment for patients with inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease. However, information on the influence of B. bifidum on gut microbial diversity of treated and pretreated IBD patients is limited.

Material/Methods

Our study investigated therapeutic and preventive effects of B. bifidum ATCC 29521 on C57BL/6 mice with dextran sulfate sodium (DSS)-induced acute colitis via 16S ribosomal ribonucleic acid (rRNA) gene sequencing.

Results

Treatment and pretreatment of mice with B. bifidum ATCC 29521 significantly alleviated the severity of acute colitis on the basis of clinical and pathologic indicators. 16S rRNA gene sequencing showed that administration of B. bifidum shifted composition of the gut microbiome in mice with DSS-induced colitis in both treated and pretreated groups. Mice pretreated with B. bifidum ATCC 29521 for 21 days exhibited a significant increase in diversity of the gut microbiome. Principal coordinate analysis showed that gut microbiota structure was shaped by different treatments and time points. On the basis of linear discriminant analysis of effect size, the abundance of the genus Escherichia-Shigella, belonging to the family Enterobacteriaceae, was reduced in the B. bifidum-treated group, indicating that pathogens were inhibited by the B. bifidum treatment. Furthermore, the genera Intestinimonas and Bacteroides were significantly associated with the B. bifidum-pretreated group.

Conclusions

16S rRNA gene sequencing showed that pretreatment with B. bifidum ATCC 29521 reduced intestinal inflammation and altered the gut microbiota to favor the genera Intestinimonas and Bacteroides.

Bifidobacterium pseudocatenulatum Ameliorates DSS-Induced Colitis by Maintaining Intestinal Mechanical Barrier, Blocking Proinflammatory Cytokines, Inhibiting TLR4/NF-κB Signaling, and Altering Gut Microbiota

This study was designed to explore the effects and discrepancy of different CLA-producing Bifidobacterium pseudocatenulatum on relieving colitis and to investigate the potential mechanisms. B. pseudocatenulatum MY40C and CCFM680 were administered to mice with DSS-induced colitis. The content of tight junction proteins and mucin2 was significantly upregulated. TNF-α and IL-6 were downregulated, while IL-10 and PPAR-γ were upregulated. TLR4/NF-κB pathway activation was significantly inhibited. Moreover, each treated strain increased Allobaculum and decreased Sutterella, Bacteroides, and Oscillospira. The colonic conjugated linoleic acid (CLA) concentrations were significantly and positively correlated with the effectiveness of strain in relieving colitis. In conclusion, MY40C and CCFM680 supplementation alleviated DSS-induced colitis by protecting intestinal mechanical barrier, modulating gut microbiota, blocking proinflammatory cytokines, and inhibiting TLR4/NF-κB pathway. These results are conducive to promote clinical trials and product development of probiotics for colitis.

Effect of a probiotic beverage consumption (Enterococcus faecium CRL 183 and Bifidobacterium longum ATCC 15707) in rats with chemically induced colitis

Background

Some probiotic strains have the potential to assist in relieving the symptoms of inflammatory bowel disease. The impact of daily ingestion of a soy-based product fermented by Enterococcus faecium CRL 183 and Lactobacillus helveticus 416 with the addition of Bifidobacterium longum ATCC 15707 on chemically induced colitis has been investigated thereof within a period of 30 days.

Methods

Colitis was induced by dextran sulfate sodium. The animals were randomly assigned into five groups: Group C: negative control; Group CL: positive control; Group CLF: DSS with the fermented product; Group CLP: DSS with the non-fermented product (placebo); Group CLS: DSS with sulfasalazine. The following parameters were monitored: disease activity index, fecal microbial analyses, gastrointestinal survival of probiotic microorganisms and short-chain fatty acids concentration in the feces. At the end of the protocol the animals’ colons were removed so as to conduct a macroscopical and histopathological analysis, cytokines and nitrite quantification.

Results

Animals belonging to the CLF group showed fewer symptoms of colitis during the induction period and a lower degree of inflammation and ulceration in their colon compared to the CL, CLS and CLP groups (p<0.05). The colon of the animals in groups CL and CLS presented severe crypt damage, which was absent in CLF and CLP groups. A significant increase in the population of Lactobacillus spp. and Bifidobacterium spp. at the end of the protocol was verified only in the CLF animals (p<0.05). This group also showed an increase in short-chain fatty acids (propionate and acetate). Furthermore, the intestinal survival of E. faecium CRL 183 and B. longum ATCC 15707 in the CLF group has been confirmed by biochemical and molecular analyzes.

Conclusions

The obtained results suggest that a regular intake of the probiotic product, and placebo to a lesser extent, can reduce the severity of DSS-induced colitis on rats.

Probiotics: The scientific evidence in the context of inflammatory bowel disease

Inflammatory bowel disease (IBD) generally comprises Crohn's disease (CD) and ulcerative colitis (UC), and their main characteristic is the intestinal mucosa inflammation. Although its origin is not yet fully known, there is growing evidence related to genetics, intestinal microbiota composition, and the immune system factors such as precursors for the initiation and progression of intestinal conditions. The use of certain probiotic microorganisms has been touted as a possible and promising therapeutic approach in reducing the risk of inflammatory bowel disease, specifically ulcerative colitis. Several mechanisms have been proposed to explain the benefits of probiotics, indicating that some bacterial strains are able to positively modulate the intestinal microbiota and the immune system, and to produce metabolites with anti-inflammatory properties. The aim of this paper is to bring together the various results and information, based on scientific evidence, that are related to probiotics and inflammatory bowel disease, emphasizing the possible mechanisms involved in this action.

Experimental and Pathalogical study of Pistacia atlantica, butyrate, Lactobacillus casei and their combination on rat ulcerative colitis model

This study evaluated the effects of Pistacia atlantica (P. atlantica), butyrate, Lactobacillus casei (L. casei) and especially their combination therapy on 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced rat colitis model. Rats were divided into seven groups. Four groups received oral P. atlantica, butyrate, L. casei and the combination of three agents for 10 consecutive days. The remaining groups were negative and positive controls and a sham group. Macroscopic and histopathological examinations were carried out along with determination of the specific biomarker of colonic oxidative stress, the myeloperoxidase (MPO). Compared with controls, the combination therapy exhibited a significant alleviation of colitis in terms of pathological scores and reduction of MPO activity (55%, p=0.0009). Meanwhile, the macroscopic appearance such as stool consistency, tissue and histopathological scores (edema, necrosis and neutrophil infiltration) were improved. Although single therapy by each P. atlantica, butyrate, and L. casei was partially beneficial in reduction of colon oxidative stress markers, the combination therapy was much more effective. In conclusion, the combination therapy was able to reduce the severity of colitis that is clear from biochemical markers. Future studies have to focus on clinical effects of this combination in management of human ulcerative colitis. Further molecular and signaling pathway studies will help to understand the mechanisms involved in the treatment of colitis and inflammatory diseases.

Probiotics, prebiotics and synbiotics- a review

The health benefits imparted by probiotics and prebiotics as well as synbiotics have been the subject of extensive research in the past few decades. These food supplements termed as functional foods have been demonstrated to alter, modify and reinstate the pre-existing intestinal flora. They also facilitate smooth functions of the intestinal environment. Most commonly used probiotic strains are: Bifidobacterium, Lactobacilli, S. boulardii, B. coagulans. Prebiotics like FOS, GOS, XOS, Inulin; fructans are the most commonly used fibers which when used together with probiotics are termed synbiotics and are able to improve the viability of the probiotics. Present review focuses on composition and roles of Probiotics, Prebiotics and Synbiotics in human health. Furthermore, additional health benefits like immune-modulation, cancer prevention, inflammatory bowel disease etc. are also discussed. Graphical abstractPictorial summary of health benefits imparted by probiotics, prebiotics and synbiotics.

Beneficial effect of butyrate, Lactobacillus casei and L-carnitine combination in preference to each in experimental colitis

AIM: To investigate the beneficial effect of the combination of butyrate, Lactobacillus casei, and L-carnitine in a rat colitis model.

METHODS: Rats were divided into seven groups. Four groups received oral butyrate, L-carnitine, Lactobacillus casei and the combination of three agents for 10 consecutive days. The remaining groups included negative and positive controls and a sham group. Macroscopic, histopathological examinations, and biomarkers such as tumor necrosis factor-alpha (TNF-α) and interlukin-1β (IL-1β), myeloperoxidase (MPO), thiobarbituric acid reactive substances (TBARS), and ferric reduced ability of plasma (FRAP) were determined in the colon.

RESULTS: The combination therapy exhibited a significant beneficial effect in alleviation of colitis compared to controls. Overall changes in reduction of TNF-α (114.66 ± 18.26 vs 171.78 ± 9.48 pg/mg protein, P < 0.05), IL-1β (24.9 ± 1.07 vs 33.06 ± 2.16 pg/mg protein, P < 0.05), TBARS (0.2 ± 0.03 vs 0.49 ± 0.04 μg/mg protein, P < 0.01), MPO (15.32 ± 0.4 vs 27.24 ± 3.84 U/mg protein, P < 0.05), and elevation of FRAP (23.46 ± 1.2 vs 15.02 ± 2.37 μmol/L, P < 0.05) support the preference of the combination therapy in comparison to controls. Although the monotherapies were also effective in improvement of colitis markers, the combination therapy was much better in improvement of colon oxidative stress markers including FRAP, TBARS, and MPO.

CONCLUSION: The present combination is a suitable mixture in control of experimental colitis and should be trialed in the clinical setting.

Anti-inflammatory properties of dairy lactobacilli

BACKGROUND

The intestinal microbiota plays an important role in human health through the modulation of innate immune responses. While selected commensal bacteria are marketed in specific probiotic products to control these responses, relatively little is known about the immune modulation potential of dairy bacteria that have principally been selected for their fermentation properties. The modulation of innate immune responses may reduce chronic inflammation in inflammatory bowel diseases like ulcerative colitis.

METHODS

A collection of dairy Lactobacillus delbrueckii strains was screened for immune modulation effects in vitro through the quantification of nuclear factor kappa B (NF-κB) activation in a human intestinal epithelial cell line. Selected bacterial strains were then tested in vivo in a mouse dextran sodium sulfate (DSS) colitis model.

RESULTS

All L. delbrueckii strains tested showed anti-inflammatory effects in vitro, to an extent that varied between strains. These effects rely on bacterial surface exposed proteins and affect the central part of the NF-κB activation pathway. One of the selected strains significantly reduced the macroscopic and microscopic symptoms of DSS-induced colitis in the mouse intestinal tract, diminished body weight loss, and improved survival.

CONCLUSIONS

The results of this study show that dairy lactobacilli that often are part of a regular diet can modulate innate immune responses, and may thus affect health more than generally thought. One of the strains tested alleviated the symptoms of DSS-induced colitis in mice, a model of human ulcerative colitis.

Toll-like receptors and their role in gastrointestinal disease

The innate immune response to invading pathogens is centred upon a family of non-clonal, germline-encoded pattern recognition receptors (PRRs), the Toll-like receptors (TLRs). These provide specificity for a vast range of microbial pathogens, and offer an immediate anti-microbial response system. Thirteen mammalian TLRs have been described; 10 are expressed in humans, each responsible for the recognition of distinct, invariant microbial structures originating from bacteria, viruses, fungi and protozoa. The two most thoroughly studied are TLR4 and TLR2, the PRRs for Gram-negative and Gram-positive bacterial products, respectively. TLR4 is also the major receptor recognising endogenous ligands released from damaged or dying cells. Activation of a TLR by its relevant ligand rapidly ignites a complex intracellular signaling cascade that ultimately results in upregulation of inflammatory genes and production of proinflammatory cytokines, interferons and recruitment of myeloid cells. It also stimulates expression, upon antigen presenting cells, of co-stimulatory molecules required to induce an adaptive immune response. Whilst a robust TLR response is critical for survival and defence against invading pathogens, inappropriate signaling in response to alterations in the local microflora environment can be detrimental. Such 'unhelpful TLR responses' could form the basis for a large number of gastrointestinal and liver disorders, including inflammatory bowel disease, viral hepatitis, autoimmune liver diseases and hepatic fibrosis. As our understanding of TLRs expands, the pathogenesis of a number of gastrointestinal disorders will be further elucidated, and this offers potential for specific therapies aimed directly at TLR signaling.