Molecular crosstalk of probiotic bacteria with the intestinal immune system: clinical relevance in the context of inflammatory bowel disease

Evidence of the Beneficial Impact of Three Probiotic-Based Food Supplements on the Composition and Metabolic Activity of the Intestinal Microbiota in Healthy Individuals: An Ex Vivo Study

Scientific evidence has increasingly supported the beneficial effects of probiotic-based food supplements on human intestinal health. This ex vivo study investigated the effects on the composition and metabolic activity of the intestinal microbiota of three probiotic-based food supplements, containing, respectively, (1) Bifidobacterium longum ES1, (2) Lactobacillus acidophilus NCFM®, and (3) a combination of L. acidophilus NCFM®, Lactobacillus paracasei Lpc-37™, Bifidobacterium lactis Bi-07™, and Bifidobacterium lactis Bl-04™. This study employed fecal samples from six healthy donors, inoculated in a Colon-on-a-plate® system. After 48 h of exposure or non-exposure to the food supplements, the effects were measured on the overall microbial fermentation (pH), changes in microbial metabolic activity through the production of short-chain and branched-chain fatty acids (SCFAs and BCFAs), ammonium, lactate, and microbial composition. The strongest effect on the fermentation process was observed for the combined formulation probiotics, characterized by the significant stimulation of butyrate production, a significant reduction in BCFAs and ammonium in all donors, and a significant stimulatory effect on bifidobacteria and lactobacilli growth. Our findings suggest that the combined formulation probiotics significantly impact the intestinal microbiome of the healthy individuals, showing changes in metabolic activity and microbial abundance as the health benefit endpoint.

Host-microbiome interaction in fish and shellfish: An overview

The importance of the gut microbiome in the management of various physiological activities including healthy growth and performance of fish and shellfish is now widely considered and being studied in detail for potential applications in aquaculture farming and the future growth of the fish industry. The gut microbiome in all animals including fish is associated with a number of beneficial functions for the host, such as stimulating optimal gastrointestinal development, producing and supplying vitamins to the host, and improving the host's nutrient uptake by providing additional enzymatic activities. Besides nutrient uptake, the gut microbiome is involved in strengthening the immune system and maintaining mucosal tolerance, enhancing the host's resilience against infectious diseases, and the production of anticarcinogenic and anti-inflammatory compounds. Because of its significant role, the gut microbiome is very often considered an "extra organ," as it plays a key role in intestinal development and regulation of other physiological functions. Recent studies suggest that the gut microbiome is involved in energy homeostasis by regulating feeding, digestive and metabolic processes, as well as the immune response. Consequently, deciphering gut microbiome dynamics in cultured fish and shellfish species will play an indispensable role in promoting animal health and aquaculture productivity. It is mentioned that the microbiome community available in the gut tract, particularly in the intestine acts as an innovative source of natural product discovery. The microbial communities that are associated with several marine organisms are the source of natural products with a diverse array of biological activities and as of today, more than 1000 new compounds have been reported from such microbial species. Exploration of such new ingredients from microbial species would create more opportunities for the development of the bio-pharma/aquaculture industries. Considering the important role of the microbiome in the whole life span of fish and shellfish, it is necessary to understand the interaction process between the host and microbial community. However, information pertaining to host-microbiome interaction, particularly at the cellular level, gene expression, metabolic pathways, and immunomodulation mechanisms, the available literature is scanty. It has been reported that there are three ways of interaction involving the host-microbe-environment operates to maintain homeostasis in the fish and shellfish gut i.e. host intrinsic factors, the environment that shapes the gut microbiome composition, and the core microbial community present in the gut system itself has equal influence on the host biology. In the present review, efforts have been made to collect comprehensive information on various aspects of host-microbiome interaction, particularly on the immune system and health maintenance, management of diseases, nutrient uptake, digestion and absorption, gene expression, and metabolism in fish and shellfish.

Genome Investigation and Functional Annotation of Lactiplantibacillus plantarum YW11 Revealing Streptin and Ruminococcin-A as Potent Nutritive Bacteriocins against Gut Symbiotic Pathogens

All nutrient-rich feed and food environments, as well as animal and human mucosae, include lactic acid bacteria known as Lactobacillus plantarum. This study reveals an advanced analysis to study the interaction of probiotics with the gastrointestinal environment, irritable bowel disease, and immune responses along with the analysis of the secondary metabolites’ characteristics of Lp YW11. Whole genome sequencing of Lp YW11 revealed 2297 genes and 1078 functional categories of which 223 relate to carbohydrate metabolism, 21 against stress response, and the remaining 834 are involved in different cellular and metabolic pathways. Moreover, it was found that Lp YW11 consists of carbohydrate-active enzymes, which mainly contribute to 37 glycoside hydrolase and 28 glycosyltransferase enzyme coding genes. The probiotics obtained from the BACTIBASE database (streptin and Ruminococcin-A bacteriocins) were docked with virulent proteins (cdt, spvB, stxB, and ymt) of Salmonella, Shigella, Campylobacter, and Yersinia, respectively. These bacteria are the main pathogenic gut microbes that play a key role in causing various gastrointestinal diseases. The molecular docking, dynamics, and immune simulation analysis in this study predicted streptin and Ruminococcin-A as potent nutritive bacteriocins against gut symbiotic pathogens.

Multiple sclerosis and obesity: The role of adipokines

Multiple Sclerosis (MS), a chronic inflammatory disease of the central nervous system that leads to demyelination and neurodegeneration has been associated with various environmental and lifestyle factors. Population-based studies have provided evidence showing the prevalence of MS is increasing worldwide. Because a similar trend has been observed for obesity and metabolic syndrome, interest has grown in possible underlying biological mechanisms shared by both conditions. Adipokines, a family of soluble factors produced by adipose tissue that participate in a wide range of biological functions, contribute to a low state of chronic inflammation observed in obesity, and influence immune function, metabolism, and nutritional state. In this review, we aim to describe epidemiological and biological factors common to MS and obesity, as well as provide an update on current knowledge of how different pro- and anti-inflammatory adipokines participate as immune response mediators in MS, as well as in the animal model for MS, namely, experimental autoimmune encephalomyelitis (EAE). Multiple Sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) leading to demyelination, and neurodegeneration. Although its pathogenesis is not yet fully understood, there is considerable evidence to suggest MS arises from complex interactions between individual genetic susceptibility and external environmental factors. In recent decades, population-based studies have provided evidence indicating the prevalence of MS is increasing worldwide, in parallel with the rise in obesity and metabolic syndrome. This synchronous increment in the incidence of both MS and obesity has led to a search for potential biological mechanisms linking both conditions. Notably, a large number of studies have established significant correlation between obesity and higher prevalence, or worse prognosis, of several immune-mediated conditions. Fat tissue has been found to produce a variety of soluble factors named adipokines. These mediators, secreted by both adipocytes as well as diverse immune cells, participate in a wide range of biological functions, further strengthening the concept of a link between immune function, metabolism, and nutritional state. Because obesity causes overproduction of pro-inflammatory adipokines (namely leptin, resistin and visfatin) and reduction of anti-inflammatory adipokines (adiponectin and apelin), adipose tissue dysregulation would appear to contribute to a state of chronic, low-grade inflammation favoring the development of disease. In this review, we present a summary of current knowledge related to the pathological effects of different adipokines, prevalent in obese MS patients.

Antibiotic Resistance to Mycobacterium tuberculosis and Potential Use of Natural and Biological Products as Alternative Anti-Mycobacterial Agents

Background: Tuberculosis (TB) is an infectious disease caused by the bacillus Mycobacterium tuberculosis (Mtb). TB treatment is based on the administration of three major antibiotics: isoniazid, rifampicin, and pyrazinamide. However, multi-drug resistant (MDR) Mtb strains are increasing around the world, thus, allowing TB to spread around the world. The stringent response is demonstrated by Mtb strains in order to survive under hostile circumstances, even including exposure to antibiotics. The stringent response is mediated by alarmones, which regulate bacterial replication, transcription and translation. Moreover, the Mtb cell wall contributes to the mechanism of antibiotic resistance along with efflux pump activation and biofilm formation. Immunity over the course of TB is managed by M1-macrophages and M2-macrophages, which regulate the immune response against Mtb infection, with the former exerting inflammatory reactions and the latter promoting an anti-inflammatory profile. T helper 1 cells via secretion of interferon (IFN)-gamma, play a protective role in the course of TB, while T regulatory cells secreting interleukin 10, are anti-inflammatory. Alternative therapeutic options against TB require further discussion. In view of the increasing number of MDR Mtb strains, attempts to replace antibiotics with natural and biological products have been object of intensive investigation. Therefore, in this review the anti-Mtb effects exerted by probiotics, polyphenols, antimicrobial peptides and IFN-gamma will be discussed. All the above cited compounds are endowed either with direct antibacterial activity or with anti-inflammatory and immunomodulating characteristics.

Salinity significantly affects intestinal microbiota and gene expression in striped catfish juveniles

In the present study, juvenile striped catfish (Pangasianodon hypophthalmus), a freshwater fish species, have been chronically exposed to a salinity gradient from freshwater to 20 psu (practical salinity unit) and were sampled at the beginning (D20) and the end (D34) of exposure. The results revealed that the intestinal microbial profile of striped catfish reared in freshwater conditions were dominated by the phyla Bacteroidetes, Firmicutes, Proteobacteria, and Verrucomicrobia. Alpha diversity measures (observed OTUs (operational taxonomic units), Shannon and Faith's PD (phylogenetic diversity)) showed a decreasing pattern as the salinities increased, except for the phylogenetic diversity at D34, which was showing an opposite trend. Furthermore, the beta diversity between groups was significantly different. Vibrio and Akkermansia genera were affected differentially with increasing salinity, the former being increased while the latter was decreased. The genus Sulfurospirillium was found predominantly in fish submitted to salinity treatments. Regarding the host response, the fish intestine likely contributed to osmoregulation by modifying the expression of osmoregulatory genes such as nka1a, nka1b, slc12a1, slc12a2, cftr, and aqp1, especially in fish exposed to 15 and 20 psu. The expression of heat shock proteins (hsp) hsp60, hsp70, and hsp90 was significantly increased in fish reared in 15 and 20 psu. On the other hand, the expression of pattern recognition receptors (PRRs) were inhibited in fish exposed to 20 psu at D20. In conclusion, the fish intestinal microbiota was significantly disrupted in salinities higher than 10 psu and these effects were proportional to the exposure time. In addition, the modifications of intestinal gene expression related to ion exchange and stressful responses may help the fish to adapt hyperosmotic environment. KEY POINTS: • It is the first study to provide detailed information on the gut microbiota of fish using the amplicon sequencing method. • Salinity environment significantly modified the intestinal microbiota of striped catfish. • Intestinal responses may help the fish adapt to hyperosmotic environment.

Microplastics as an aquatic pollutant affect gut microbiota within aquatic animals

The adverse impact of microplastics (MPs) on gut microbiota within aquatic animals depends on the overall effect of chemicals and biofilm of MPs. Thus, it is ideal to fully understand the influences that arise from each or even all of these characteristics, which should give us a whole picture of consequences that are brought by MPs. Harmful effects of MPs on gut microbiota within aquatic organisms start from the ingestion of MPs by aquatic organisms. According to this, the present review will discuss the ingestion of MPs and its following results on gut microbial communities within aquatic animals, in which chemical components, such as plastic polymers, heavy metals and POPs, and the biofilm of MPs would be involved. This review firstly analyzed the impacts of MPs on aquatic organisms in detail about its chemical components and biofilm based on previous relevant studies. At last, the significance of field studies, functional studies and complex dynamics of gut microbial ecology in the future research of MPs affecting gut microbiota is discussed.

Bifidobacterium bifidum BGN4 Paraprobiotic Supplementation Alleviates Experimental Colitis by Maintaining Gut Barrier and Suppressing Nuclear Factor Kappa B Activation Signaling Molecules

Inflammatory bowel diseases, including Crohn's disease and ulcerative colitis, are characterized by chronic gastrointestinal inflammation with continuous relapse-remission cycles. This study aimed to evaluate the protective effect of Bifidobacterium bifidum BGN4 as a probiotic or paraprobiotic against dextran sulfate sodium (DSS)-induced colitis in mice. Ten-week-old female BALB/c mice were randomly divided into five groups. The control (CON) and DSS groups received oral gavage of PBS, whereas the live B. bifidum (LIVE), heat-killed B. bifidum BGN4 (HEAT), and lysozyme-treated B. bifidum BGN4 (LYSOZYME) groups received live B. bifidum BGN4, heat-killed B. bifidum BGN4, and lysozyme-treated B. bifidum BGN4, respectively, for 10 days, followed by DSS supply to induce colitis. The paraprobiotic (HEAT and LYSOZYME) groups had less body weight loss and colon length shortening than the DSS or LIVE groups. The LYSOZYME group exhibited better preserved intestinal barrier integrity than the LIVE group by upregulating gap junction protein expression possibly through activating NOD-like receptor family pyrin domain containing 6/caspase-1/interleukin (IL)-18 signaling. The LYSOZYME group showed downregulated proinflammatory molecules, including p-inhibitor of kappa B proteins alpha (IκBα), cycloxygenase 2 (COX2), IL-1β, and T-bet, whereas the expression of the regulatory T cell transcription factor, forkhead box P3 expression, was increased. The paraprobiotic groups showed distinct separation of microbiota distribution and improved inflammation-associated dysbiosis. These results suggest that B. bifidum BGN4 paraprobiotics, especially lysozyme-treated BGN4, have a preventive effect against DSS-induced colitis, impacting intestinal barrier integrity, inflammation, and dysbiosis.

The Lactobacillus as a Probiotic: Focusing on Liver Diseases

Over the past decade, scientific evidence for the properties, functions, and beneficial effects of probiotics for humans has continued to accumulate. Interest in the use of probiotics for humans has increased tremendously. Among various microorganisms, probiotics using bacteria have been widely studied and commercialized, and, among them, Lactobacillus is representative. This genus contains about 300 species of bacteria (recently differentiated into 23 genera) and countless strains have been reported. They improved a wide range of diseases including liver disease, gastrointestinal diseases, respiratory diseases, and autoimmune diseases. Here, we intend to discuss in depth the genus Lactobacillus as a representative probiotic for chronic liver diseases.

The Role of Gut and Lung Microbiota in Susceptibility to Tuberculosis

Tuberculosis is one of the most common infectious diseases and infectious causes of death worldwide. Over the last decades, significant research effort has been directed towards defining the understanding of the pathogenesis of tuberculosis to improve diagnosis and therapeutic options. Emerging scientific evidence indicates a possible role of the human microbiota in the pathophysiology of tuberculosis, response to therapy, clinical outcomes, and post-treatment outcomes. Although human studies on the role of the microbiota in tuberculosis are limited, published data in recent years, both from experimental and clinical studies, suggest that a better understanding of the gut-lung microbiome axis and microbiome-immune crosstalk could shed light on the specific pathogenetic mechanisms of Mycobacterium tuberculosis infection and identify new therapeutic targets. In this review, we address the current knowledge of the host immune responses against Mycobacterium tuberculosis infection, the emerging evidence on how gut and lung microbiota can modulate susceptibility to tuberculosis, the available studies on the possible use of probiotic-antibiotic combination therapy for the treatment of tuberculosis, and the knowledge gaps and future research priorities in this field.

Functional capabilities of probiotic strains on attenuation of intestinal epithelial cell inflammatory response induced by TLR4 stimuli

Intestinal epithelial cells (IECs) respond to intruders and their cellular molecules by displaying inflammatory state that can be abrogated by probiotics. However, the molecular mechanisms underlying the beneficial activity of probiotic strains have yet to be elucidated. This study was conducted to investigate whether probiotic strains have immunoregulatory effects in IECs, and how they respond to bacterial lipopolysaccharide (LPS) in vitro. Caco2 cells were stimulated with LABs and followed by LPS. The expression of different cytokines that involved in toll-like receptor (TLR) signaling was analyzed. Caco2 cells that were exposed to LPS showed upregulated expression of IL-6, CXCL8, CCL2, and BPI that were counteracted by LAB strains through the modulation of TLR negative regulators (A20, Tollip, SIGIRR, and IRAKM), p38 MAPK and p65 NF-κB signaling. Lactobacillus plantarum, L. farciminis, and L. pentosus unveiled better activity as compared to other strains. Moreover, LAB strains were the potent inducers of immunoregulatory cytokines in coculture system. The expression of IL-10 and TGF-β were found to be higher as compared with LPS. Conversely, TNF-α at the protein level was dampened by LAB strains in both the apical and basolateral compartments. Collectively, our results demonstrated that the selected LAB strains exert profound immunoregulatory effects in response to LPS on IECs; however, further studies in vivo and in clinical settings are important to corroborate these effects. © 2018 BioFactors, 45(2):223-235, 2019.

The evidence for microbiome manipulation in inflammatory arthritis

The human body consists of millions of commensal bacteria (the microbiome), with the intestinal tract being the most prevalent site of colonization. This colonization process begins at birth, and despite numerous factors such as ageing, diet and drug use affecting the microbiome make-up, by adulthood the composition of the gut bacteria is relatively consistent across local populations. The recent advent of new scientific techniques has enabled us to explore how the microbiome affects health and, in particular, has shed light on the involvement of the microbiome in the pathogenesis of inflammatory disease. In this review we highlight the current evidence for microbiome manipulation in inflammatory arthritis in animal and human models and discuss potential therapeutics targeting the microbiome as treatment for these diseases.

Lactobacillus acidophilus alleviates the inflammatory response to enterotoxigenic Escherichia coli K88 via inhibition of the NF-κB and p38 mitogen-activated protein kinase signaling pathways in piglets

Background

A newly isolated L. acidophilus strain has been reported to have potential anti-inflammatory activities against lipopolysaccharide (LPS) challenge in piglet, while the details of the related inflammatory responses are limited. Here we aimed to analysis the ability of L. acidophilus to regulate inflammatory responses and to elucidate the mechanisms involved in its anti-inflammatory activity.

Results

The ETEC (enterotoxigenic Escherichia coli) K88-induced up-regulations of IL-1β, IL-8 and TNF-α were obviously inhibited by L. acidophilus while IL-10 was significantly increased. Moreover, L. acidophilus down-regulated pattern recognition receptors TLR (Toll-like receptor) 2 and TLR4 expression in both spleen and mesenteric lymph nodes of ETEC-challenged piglets, in accompanied with the reduced phosphorylation levels of nuclear factor kappa B (NF-κB) p65 and mitogen-activated protein kinase (MAPK) p38 as well in spleen of ETEC-infected piglets. Furthermore, L.acidophilus significantly increased the expression of the negative regulators of TLRs signaling, including Tollip, IRAK-M, A20 and Bcl-3 in spleen of ETEC-challenged piglets.

Conclusions

Our findings suggested that L. acidophilus regulated inflammatory response to ETEC via impairing both NF-κB and MAPK signaling pathways in piglets.

Koch's postulates, microbial dysbiosis and inflammatory bowel disease

Over the past 20 years, a growing amount of evidence supports the role of microbes and an imbalanced microbiota in inflammatory bowel disease (IBD). While many reviews have been written on the microbiota in IBD, few have considered how they fulfil the Koch's postulates. In this review, we consider how the Koch's postulates might be modified so that they can be fulfilled for polymicrobial diseases, and we discuss the progress made to date in fulfilling them.

Characterization of the anti-inflammatory Lactobacillus reuteri BM36301 and its probiotic benefits on aged mice

Background

The gut microbiota is playing more important roles in host immune regulation than was initially expected. Since many benefits of microbes are highly strain-specific and their mechanistic details remain largely elusive, further identification of new probiotic bacteria with immunoregulatory potentials is of great interest.

Results

We have screened our collection of probiotic lactic acid bacteria (LAB) for their efficacy in modulating host immune response. Some LAB are characterized by suppression of TNF-α induction when LAB culture supernatants are added to THP-1 cells, demonstrating the LAB’s anti-inflammatory potential. These suppressive materials were not inactivated by heat or trypsin. On the other hand, treatment of THP-1 directly with live bacterial cells identified a group of pro-inflammatory LAB, which stimulated significant production of TNF-α. Among those, we chose the Lactobacillus reuteri BM36301 as an anti-inflammatory strain and the L. reuteri BM36304 as a pro-inflammatory strain, and further studied their in vivo effects. We supplied C57BL/6 mice with these bacteria in drinking water while feeding them a standard diet for 20 weeks. Interestingly, these L. reuteri strains evoked different consequences depending on the gender of the mice. That is, males treated with anti-inflammatory BM36301 experienced less weight gain and higher testosterone level; females treated with BM36301 maintained lower serum TNF-α as well as healthy skin with active folliculogenesis and hair growth. Furthermore, while males treated with pro-inflammatory BM36304 developed higher serum levels of TNF-α and insulin, in contrast females did not experience such effects from this bacteria strain.

Conclusion

The L. reuteri BM36301 was selected as an anti-inflammatory strain in vitro. It helped mice maintain healthy conditions as they aged. These findings propose the L. reuteri BM36301 as a potential probiotic strain to improve various aspects of aging issues.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0686-7) contains supplementary material, which is available to authorized users.

Administration of Lactobacillus helveticus NS8 improves behavioral, cognitive, and biochemical aberrations caused by chronic restraint stress

Increasing numbers of studies have suggested that the gut microbiota is involved in the pathophysiology of stress-related disorders. Chronic stress can cause behavioral, cognitive, biochemical, and gut microbiota aberrations. Gut bacteria can communicate with the host through the microbiota-gut-brain axis (which mainly includes the immune, neuroendocrine, and neural pathways) to influence brain and behavior. It is hypothesized that administration of probiotics can improve chronic-stress-induced depression. In order to examine this hypothesis, the chronic restraint stress depression model was established in this study. Adult specific pathogen free (SPF) Sprague-Dawley rats were subjected to 21 days of restraint stress followed by behavioral testing (including the sucrose preference test (SPT), elevated-plus maze test, open-field test (OFT), object recognition test (ORT), and object placement test (OPT)) and biochemical analysis. Supplemental Lactobacillus helveticus NS8 was provided every day during stress until the end of experiment, and selective serotonin reuptake inhibitor (SSRI) citalopram (CIT) served as a positive control. Results showed that L. helveticus NS8 improved chronic restraint stress-induced behavioral (anxiety and depression) and cognitive dysfunction, showing an effect similar to and better than that of CIT. L. helveticus NS8 also resulted in lower plasma corticosterone (CORT) and adrenocorticotropic hormone (ACTH) levels, higher plasma interleukin-10 (IL-10) levels, restored hippocampal serotonin (5-HT) and norepinephrine (NE) levels, and more hippocampal brain-derived neurotrophic factor (BDNF) mRNA expression than in chronic stress rats. Taken together, these results indicate an anti-depressant effect of L. helveticus NS8 in rats subjected to chronic restraint stress depression and that this effect could be due to the microbiota-gut-brain axis. They also suggest the therapeutic potential of L. helveticus NS8 in stress-related and possibly other kinds of depression.

A Microbial Feed Additive Abates Intestinal Inflammation in Atlantic Salmon

The efficacy of a microbial feed additive (Bactocell^®) in countering intestinal inflammation in Atlantic salmon was examined in this study. Fish were fed either the additive-coated feed (probiotic) or feed without it (control). After an initial 3-week feeding, an inflammatory condition was induced by anally intubating all the fish with oxazolone. The fish were offered the feeds for 3 more weeks. Distal intestine from the groups was obtained at 4 h, 24 h, and 3 weeks, after oxazolone treatment. Inflammatory responses were prominent in both groups at 24 h, documented by changes in intestinal micromorphology, expression of inflammation-related genes, and intestinal proteome. The control group was characterized by edema, widening of intestinal villi and lamina propria, infiltration of granulocytes and lymphocytes, and higher expression of genes related to inflammatory responses, mul1b, il1b, tnfa, ifng, compared to the probiotic group or other time points of the control group. Further, the protein expression in the probiotic group at 24 h after inducing inflammation revealed five differentially regulated proteins – Calr, Psma5, Trp1, Ctsb, and Naga. At 3 weeks after intubation, the inflammatory responses subsided in the probiotic group. The findings provide evidence that the microbial additive contributes to intestinal homeostasis in Atlantic salmon.

Modulation of acute phase parameters of inflammation by probiotics in albino rats

We investigated the effect of the probiotic Lactobacillus acidophilus on acute phase parameters in infected animals and to evaluate its possible use as alternative to replace the classical anti-inflammatory drugs as a trial to avoid the side effect of these drugs and its disadvantages. Forty albino rats were divided into four groups, group A was given saline orally and kept as normal-control rats, group B was orally given Lactobacillus acidophilus at a dose regimen of 108 CFU/day and kept as normal-treated rats for 6 weeks, group C was experimentally infected with Salmonella typhimurium (0.2 mL of 1.5 × 108 CFU/mL) and received saline orally to be kept as diseased-control rats, while group D was orally given Lactobacillus acidophilus (108 CFU/day) for 6 weeks and experimentally infected with Salmonella typhimurium and kept as diseased-treated rats. Results of group D revealed significant decrease in ESR, fibrinogen, TIBC, UIBC, and ceruloplasmin, especially on the 34th day post infection. On the other hand, significant increase in total proteins, albumin, total iron, and transferrin saturation percentage was revealed, when compared with group C. These data indicate that the probiotic Lactobacillus acidophilus may alter acute phase proteins after infection and significantly reduce the degree of inflammation.

Effects of rhubarb on intestinal flora and toll-like receptors of intestinal mucosa in rats with severe acute pancreatitis

OBJECTIVE

The aim of this study was to examine the effects of rhubarb on intestinal flora and toll-like receptors (TLRs) of intestinal mucosa in rats with severe acute pancreatitis (SAP).

METHODS

Healthy male Sprague-Dawley rats were randomly allocated into sham-operated surgical model of SAP without or with postoperative rhubarb treatment groups (7 in each group). Rats in with rhubarb group received 10% rhubarb decoction (1 mL/200 g) through tube feeding at every 8 hours during postoperative 24 hours. Serum amylase, amount of intestinal flora, and TLR2/TLR4 messenger RNA expression in intestinal mucosa were tested among 3 groups at postoperative 24 hours.

RESULTS

TLR2 and TLR4 messenger RNA expression levels in intestinal mucosa in SAP without rhubarb group were significantly higher than those in sham-operated or SAP with rhubarb groups (P < 0.05). The amount of intestinal lactobacilli and bifidobacteria in SAP without rhubarb group were significantly fewer than in those sham-operated group (P < 0.05) but not significantly different from those in SAP with rhubarb group (P > 0.05). The amount of intestinal Escherichia coli was relatively higher in SAP group than in sham-operated group (P > 0.05) but lesser in rhubarb treatment group (P > 0.05).

CONCLUSIONS

Rhubarb might maintain the intestinal mucosal barrier through regulating intestinal flora and inhibiting intestinal inflammatory response in rats with SAP.

The effect of probiotics on immune regulation, acne, and photoaging

Probiotics are live micro-organisms that provide a health benefit to the host. The role of probiotics in the management of disease, as well as immune modification, has recently experienced a renewed interest in society, as probiotics can be found in products ranging from yogurt to facial creams. In this article, we discuss the role of probiotics in the development of the immune system, the treatment of acne and rosacea, and protection against aging and photodamage.

Lactobacillus paracasei CNCM I-4034 and its culture supernatant modulate Salmonella-induced inflammation in a novel transwell co-culture of human intestinal-like dendritic and Caco-2 cells

Background

The action of probiotics has been studied in vitro in cells isolated from both mice and humans, particularly enterocytes (IECs), dendritic cells (DCs) and co-cultures of peripheral DCs and IECs. Peripheral DCs and murine DCs differ from human gut DCs, and to date there are no data on the action of any probiotic on co-cultured human IECs and human intestinal DCs. To address this issue, a novel transwell model was used. Human IECs (Caco-2 cells) grown in the upper chamber of transwell filters were co-cultured with intestinal-like human DCs grown in the basolateral compartment of the transwells. The system was apically exposed for 4 h to live probiotic L. paracasei CNCM I-4034 obtained from the faeces of breastfed infants or to its cell-free culture supernatant (CFS) and challenged with Salmonella typhi. The secretion of pro- and anti-inflammatory cytokines in the basolateral compartment was determined by immunoassay, and the DC expression pattern of 20 TLR signaling pathway genes was analysed by PCR array.

Results

The presence of the live probiotic alone significantly increased IL-1β, IL-6, IL-8, TGF-β2, RANTES and IP-10 levels and decreased IL-12p40, IL-10, TGF- β1 and MIP-1α levels. This release was correlated with a significant increase in the expression of almost all TLR signaling genes. By contrast, incubation of the co-culture with CFS increased IL-1β, IL-6, TGF-β2 and IP-10 production only when Salmonella was present. This induction was correlated with an overall decrease in the expression of all TLR genes except TLR9, which was strongly up-regulated.

Conclusions

The data presented here clearly indicate that L. paracasei CNCM I-4034 significantly increases the release of pro-inflammatory cytokines, enhances TLR signaling pathway activation and stimulates rather than suppresses the innate immune system. Furthermore, our findings provide evidence that the effects of probiotics in the presence of IECs and DCs differ from the effects of probiotics on cultures of each cell type alone, as reported by us earlier. Thus, co-culture systems such as the one described here are needed to characterise the effects of probiotics in vitro, highlighting the potential utility of such co-cultures as a model system.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-015-0408-6) contains supplementary material, which is available to authorized users.

[Characterization, influence and manipulation of the gastrointestinal microbiota in health and disease]

The gastrointestinal tract harbors trillions of microorganisms that are indispensable for health. The gastrointestinal microbiota can be studied using culture and molecular methods. The applications of massive sequencing are constantly increasing, due to their high yield, increasingly accessible costs, and the availability of free software for data analysis. The present article provides a detailed review of a large number of studies on the gastrointestinal microbiota and its influence on human health; particular emphasis is placed on the evidence suggesting a relationship between the gastrointestinal microbial ecosystem and diverse physiological and immune/inflammatory processes. Discussion of the articles analyzed combines a medical approach and current concepts of microbial molecular ecology. The present revision aims to be useful to those interested in the gastrointestinal microbiota and its possible alteration to maintain, re-establish and enhance health in the human host.

Intestinal microbiota: its role in digestive diseases

It is now well known that intestinal microbiota exerts not only several physiological functions, but has also been implied in the mechanisms of many conditions, both intestinal and extraintestinal. These advances, to the best of our knowledge, have been made possible by the development of new ways of studying gut flora. Metagenomics, the study of genetic material taken directly from environmental samples, avoiding individual culture, has become an excellent tool to study the human microbiota. Therefore, it has demonstrated an association between an altered intestinal microbiota and inflammatory bowel disease or irritable bowel syndrome, perhaps the most extensively studied conditions associated with this particular subject. However, microbiota has a potential role in the development of other diseases; their manifestations are not confined to the intestine only. In this article, an extensive updated review is conducted on the role intestinal microbiota has in health and in different diseases. Focus is made on the following conditions: inflammatory bowel disease, irritable bowel syndrome, celiac disease, hepatic encephalopathy, and obesity.

Effects of chitosan on intestinal inflammation in weaned pigs challenged by enterotoxigenic Escherichia coli

The aim of this study was to investigate whether supplementation with chitosan (COS) could reduce diarrhea and to explore how COS alleviates intestinal inflammation in weaned pigs. Thirty pigs (Duroc×Landrace×Yorkshire, initial BW of 5.65±0.27) weaned at age 21 d were challenged with enterotoxigenic Escherichia coli during a preliminary trial period, and then divided into three treatment groups. Pigs in individual pens were fed a corn-soybean meal diet, that contained either 0 (control), 50 mg/kg chlortetracycline, or 300 mg/kg COS for 21 days. The post-weaning diarrhea frequency, calprotectin levels and TLR4 protein expression were decreased (P<0.05) in both the COS and chlortetracycline groups compared with control. Simultaneously, supplemental COS and chlortetracycline had no effect on the mRNA expression of TNF-α in the jejunal mucosa, or on the concentrations of IL-1β, IL-6 and TNF-α in serum. However, COS supplementation improved (P<0.05) the mRNA expression of IL-1β and IL-6 in the jejunal mucosa. The results indicate that supplementation with COS at 300 mg/kg was effective for alleviating intestinal inflammation and enhancing the cell-mediated immune response. As feed additives, chitosan and chlortetracycline may influence different mechanisms for alleviating inflammation in piglets.

Gut barrier dysfunction and microbial translocation in cancer cachexia: a new therapeutic target

Purpose of Review

Cachexia is a complex metabolic syndrome characterized by skeletal muscle and adipose tissue loss and is frequently associated with emaciation, anorexia, systemic inflammation, and metabolic dysfunction. Lack of a clear understanding of the cause of cancer cachexia has impeded progress in identifying effective therapeutic agents. This review summarizes recent publications on the role of gut barrier function, intestinal microbiota, and inflammation in the etiology of cancer cachexia and new therapeutic interventions that may benefit treatment strategies.

Recent Findings

Significant advances have been made in understanding the composition and metabolic capabilities of the intestinal microbiota and its impact on gut barrier function with implications for certain inflammatory-based diseases. Recent studies reported associations between intestinal permeability and endotoxemia with development of cancer cachexia and other metabolic disorders. Improvements in intestinal function and weight gain along with decreased inflammation have been reported for potential therapeutic agents such as eicosapentaenoic acid, immunoglobulin isolates, and probiotics.

Summary

Continued progress in the scientific understanding of the complex interplay between the intestinal microbiota, gut barrier function, and host inflammatory responses will uncover new therapeutic targets to help avoid the serious metabolic alterations associated with cachexia.

Role of toll-like receptor 4 in colorectal carcinogenesis: a meta-analysis

OBJECTIVE

This meta-analysis was performed to evaluate the role of toll-like receptor 4 (TLR-4) in colorectal carcinogenesis.

METHODS

The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched from inception through November 1st, 2013 without language restrictions. Odds ratios (ORs) or standardized mean differences (SMD) with their 95% confidence intervals (CI) were calculated.

RESULTS

Fourteen case-control studies met the inclusion criteria for this meta-analysis. A total of 1,209 colorectal cancer (CRC) cases and 1,218 healthy controls were involved in this meta-analysis. Two common polymorphisms (299 A>G and 399 C>T) in the TLR-4 gene, TLR-4 mRNA and protein expression were assessed. Our meta-analysis results revealed that the TLR-4 399 C>T polymorphism might increase the risk of CRC (allele model: OR = 1.77, 95%CI = 1.32 ∼ 2.36, P<0.001; dominant model: OR = 1.83, 95%CI = 1.32 ∼ 2.52, P<0.001; respectively). However, we found no correlation between the TLR-4 299 A>G polymorphism and CRC risk (all P>0.05). A subgroup analysis by ethnicity suggested that TLR-4 genetic polymorphisms were associated with an increased risk of CRC among Asians (allele model: OR = 1.50, 95%CI = 1.19 ∼ 1.88, P = 0.001; dominant model: OR = 1.49, 95%CI = 1.16 ∼ 1.92, P = 0.002; respectively), but not among Caucasians and Africans (all P>0.05). Furthermore, our results showed that TLR-4 mRNA and protein levels in CRC patients were higher than those in healthy controls (TLR-4 mRNA: SMD = 2.51, 95%CI  = 0.98 ∼ 4.05, P = 0.001; TLR-4 protein: OR  = 4.75, 95%CI  = 1.16 ∼ 19.36, P = 0.030; respectively).

CONCLUSION

Our findings provide empirical evidence that TLR-4 may play an important role in colorectal carcinogenesis. Thus, TLR-4 is a promising potential biomarker for the early diagnosis of CRC.

Antibodies to Lactobacilli and Bifidobacteria in young children with different propensity to develop islet autoimmunity

The intestinal microbiota is essential to the maturation and homeostasis of the immune system. Immunoblot assays were used to establish the prevalence of serum IgG, IgM, and IgA antibodies specific for Bifidobacterium adolescentis, Bifidobacterium longum, and Lactobacillus rhamnosus GG proteins in young children presenting with or without type 1 diabetes (T1D). We demonstrated that children between the ages of 6 and 12 months had a substantial increase in the frequency of IgG antibodies specific for L. rhamnosus GG proteins. We measured IgG, IgM, and IgA class antibody reactivity against B. adolescentis DSM 20083, B. adolescentis DSM 20086, and B. longum DSM 20088 proteins demonstrating significantly higher IgA responses against B. adolescentis DSM 20083 strain proteins in children who developed islet autoimmunity and T1D later in life. B. adolescentis strains showed more IgM type antibodies in children who developed T1D later in life, but the difference was not statistically significant. B. longum proteins were recognized by IgG and IgA antibodies to a higher extent compared to other bacteria studied. These results confirm that differences in immune reactivity against some commensal strains in young children may represent a different risk factor for developing T1D.

The commensal bacterium Faecalibacterium prausnitzii is protective in DNBS-induced chronic moderate and severe colitis models

BACKGROUND

The abundance of Faecalibacterium prausnitzii, an abundant and representative bacterium of Firmicutes phylum, has consistently been observed to be lower in patients with Crohn's disease than in healthy individuals. We have shown that both F. prausnitzii and its culture supernatant (SN) have anti-inflammatory and protective effects in a TNBS-induced acute colitis mouse model. Here, we tested the effects of both F. prausnitzii and its SN in moderate and severe DNBS-induced chronic colitis mouse models.

METHODS

Colitis was induced by intrarectal administration of DNBS. After either 4 or 10 days of recovery (severe and moderate protocols, respectively), groups of mice were intragastrically administered either with F. prausnitzii A2-165 or with its culture SN for 7 or 10 days. Three days before being sacrificed, colitis was reactivated by administration of a lower dose of DNBS. The severity of colitis at the time of being sacrificed was assessed by weight loss and macroscopic and microscopic scores. Myeloperoxidase (MPO) activity, cytokine levels, lymphocyte populations, and changes in microbiota were studied.

RESULTS

Intragastric administration of either F. prausnitzii or its SN led to a significant decrease in colitis severity in both severe and moderate chronic colitis models. The lower severity of colitis was associated with down-regulation of MPO, pro-inflammatory cytokines, and T-cell levels.

CONCLUSIONS

We show, for the first time, protective effects of both F. prausnitzii and its SN during both the period of recovery from chronic colitis and colitis reactivation. These results provide further evidence that F. prausnitzii is an anti-inflammatory bacterium with therapeutic potential for patients with inflammatory bowel disease.

Role of "Western diet" in inflammatory autoimmune diseases

Developed societies, although having successfully reduced the burden of infectious disease, constitute an environment where metabolic, cardiovascular, and autoimmune diseases thrive. Living in westernized countries has not fundamentally changed the genetic basis on which these diseases emerge, but has strong impact on lifestyle and pathogen exposure. In particular, nutritional patterns collectively termed the "Western diet", including high-fat and cholesterol, high-protein, high-sugar, and excess salt intake, as well as frequent consumption of processed and 'fast foods', promote obesity, metabolic syndrome, and cardiovascular disease. These factors have also gained high interest as possible promoters of autoimmune diseases. Underlying metabolic and immunologic mechanisms are currently being intensively explored. This review discusses the current knowledge relative to the association of "Western diet" with autoimmunity, and highlights the role of T cells as central players linking dietary influences to autoimmune pathology.

Probiotics, prebiotics, synbiotics in prevention and treatment of inflammatory bowel diseases

Probiotics, prebiotics, and synbiotics are functional components able to exert positive effects on human health. Numerous medical conditions lack effective and safe approaches for prevention or treatment, thus usage of probiotics, prebiotics, and synbiotics is an alternative. Further, the benefit related to the consumption of these compounds is associated with lower morbidity of chronic diseases and reduced health-care costs. Various types of mediums to deliver probiotics/synbiotics to the human GIT are used. Although capsules and tablets are frequently applied as delivery systems for probiotics, the major challenge of the commercial sector is to market new functional foods containing probiotics and/or prebiotics. Discovering of new probiotic/synbiotic functional foods is connected to the interest of the food industry to revitalize continuously through introduction of products with improved nutritional value and pleasant taste, but also with health benefit for the consumers. The review provides insights and new perspectives in respect to usage of functional components and foods in prevention and treatment of inflammatory bowel diseases (IBD) that are highly correlated with the modern lifestyle. The therapeutic and safety properties of probiotics and prebiotics, their role in pathogenesis of IBD, potential to prevent and treat these diseases as well as postulated mechanisms of action will be discussed, highlighting the main areas in which further research is an emergence.

Role of commensal and probiotic bacteria in human health: a focus on inflammatory bowel disease

The human gut is one of the most complex ecosystems, composed of 1013-1014 microorganisms which play an important role in human health. In addition, some food products contain live bacteria which transit through our gastrointestinal tract and could exert beneficial effects on our health (known as probiotic effect). Among the numerous proposed health benefits attributed to commensal and probiotic bacteria, their capacity to interact with the host immune system is now well demonstrated. Currently, the use of recombinant lactic acid bacteria to deliver compounds of health interest is gaining importance as an extension of the probiotic concept. This review summarizes some of the recent findings and perspectives in the study of the crosstalk of both commensal and probiotic bacteria with the human host as well as the latest studies in recombinant commensal and probiotic bacteria. Our aim is to highlight the potential roles of recombinant bacteria in this ecosystem.

Modulation of anti-inflammatory response in lipopolysaccharide stimulated human THP-1 cell line and mouse model at gene expression level with indigenous putative probiotic lactobacilli

The anti-inflammatory potential of eight indigenous probiotic Lactobacillus isolates was evaluated in vitro in terms of modulating the expression of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in human acute monocytic leukemia (THP-1) cells under inflammatory conditions. Amongst these, Lactobacillus plantarum Lp91 was the most potent anti-inflammatory strain as it evoked a significant (P < 0.001) down-regulation of TNF-α by -1.45-fold relative to the control in THP-1 cells. However, in terms of IL-6 expression, all the strains could up-regulate its expression considerably at different levels. Hence, based on in vitro expression of TNF-α, Lp91 was selected for in vivo study in lipopolysaccharide (LPS)-induced mouse model to look at the expression of TNF-α, IL-6, monocyte chemotactic protein-1 (MCP-1), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule (ICAM-1) and E-selectin in mouse aorta. In LPS challenged (2 h) mice group fed with Lp91 for 10 days, TNF-α, IL-6, MCP-1, VCAM-1, ICAM-1 and E-selectin expressions were significantly down-regulated by 3.10-, 10.02-, 4.22-, -3.14-, 2.28- and 5.71-fold relative to control conditions. In conclusion, Lp91 could serve as a candidate probiotic strain to explore it as a possible biotherapeutic anti-inflammatory agent against inflammatory diseases including cardiovascular disease.

Probiotics in the management of lung diseases

The physiology and pathology of the respiratory and gastrointestinal tracts are closely related. This similarity between the two organs may underlie why dysfunction in one organ may induce illness in the other. For example, smoking is a major risk factor for COPD and IBD and increases the risk of developing Crohn's disease. Probiotics have been defined as "live microorganisms which, when administered in adequate amounts, confer health benefits on the host." In model systems probiotics regulate innate and inflammatory immune responses. Commonly used probiotics include lactic acid bacteria, particularly Lactobacillus, Bifidobacterium, and Saccharomyces, and these are often used as dietary supplements to provide a health benefit in gastrointestinal diseases including infections, inflammatory bowel disease, and colon cancer. In this respect, probiotics probably act as immunomodulatory agents and activators of host defence pathways which suggest that they could influence disease severity and incidence at sites distal to the gut. There is increasing evidence that orally delivered probiotics are able to regulate immune responses in the respiratory system. This review provides an overview of the possible role of probiotics and their mechanisms of action in the prevention and treatment of respiratory diseases.

Nutritional protective mechanisms against gut inflammation

Inflammatory bowel disease (IBD) is a debilitating and widespread immune-mediated illness characterized by excessive inflammatory and effector mucosal responses leading to tissue destruction at the gastrointestinal tract. Interactions among the immune system, the commensal microbiota and the host genotype are thought to underlie the pathogenesis of IBD. However, the precise etiology of IBD remains unknown. Diet-induced changes in the composition of the gut microbiome can modulate the induction of regulatory versus effector immune responses at the gut mucosa and improve health outcomes. Therefore, manipulation of gut microbiota composition and the local production of microbial-derived metabolites by using prebiotics, probiotics and dietary fibers is being explored as a promising avenue of prophylactic and therapeutic intervention against gut inflammation. Prebiotics and fiber carbohydrates are fermented by resident microflora into short chain fatty acids (SCFAs) in the colon. SCFAs then activate peroxisome proliferator-activated receptor (PPAR)γ, a nuclear transcription factor with widely demonstrated anti-inflammatory efficacy in experimental IBD. The activation of PPARγ by naturally ocurring compounds such as conjugated linoleic acid, pomegranate seed oil-derived punicic acid, eleostearic acid and abscisic acid has been explored as nutritional interventions that suppress colitis by directly modulating the host immune response. The aim of this review is to summarize the status of innovative nutritional interventions against gastrointestinal inflammation, their proposed mechanisms of action, preclinical and clinical efficacy as well as bioinformatics and computational modeling approaches that accelerate discovery in nutritional and mucosal immunology research.

Nutritional and probiotic supplementation in colitis models

In vitro and animals models have long been used to study human diseases and identify novel therapeutic approaches that can be applied to combat these conditions. Ulcerative colitis and Crohn's disease are the two main entities of inflammatory bowel disease (IBD). There is an intricate relationship between IBD features in human patients, in vitro and animal colitis models, mechanisms and possible therapeutic approaches in these models, and strategies that can be extrapolated and applied in humans. Malnutrition, particularly protein-energy malnutrition and vitamin and micronutrient deficiencies, as well as dysregulation of the intestinal microbiota, are common features of IBD. Based on these observations, dietary supplementation with essential nutrients known to be in short supply in the diet in IBD patients and with other molecules believed to provide beneficial anti-inflammatory effects, as well as with probiotic organisms that stimulate immune functions and resistance to infection has been tested in colitis models. Here we review current knowledge on nutritional and probiotic supplementation in in vitro and animal colitis models. While some of these strategies require further fine-tuning before they can be applied in human IBD patients, their intended purpose is to prevent, delay or treat disease symptoms in a non-pharmaceutical manner.

Lactocepin secreted by Lactobacillus exerts anti-inflammatory effects by selectively degrading proinflammatory chemokines

The intestinal microbiota has been linked to inflammatory bowel diseases (IBD), and oral treatment with specific bacteria can ameliorate IBD. One bacterial mixture, VSL#3, containing Lactobacillus, Bifidobacterium, and Streptococcus, was clinically shown to reduce inflammation in IBD patients and normalize intestinal levels of IP-10, a lymphocyte-recruiting chemokine, in a murine colitis model. We identified Lactobacillus paracasei prtP-encoded lactocepin as a protease that selectively degrades secreted, cell-associated, and tissue-distributed IP-10, resulting in significantly reduced lymphocyte recruitment after intraperitoneal injection in an ileitis model. A human Lactobacillus casei isolate was also found to encode lactocepin and degrade IP-10. L. casei feeding studies in a murine colitis model (T cell transferred Rag2(-/-) mice) revealed that a prtP-disruption mutant was significantly less potent in reducing IP-10 levels, T cell infiltration and inflammation in cecal tissue compared to the isogenic wild-type strain. Thus, lactocepin-based therapies may be effective treatments for chemokine-mediated diseases like IBD.

Apple polyphenols extract (APE) improves colon damage in a rat model of colitis

BACKGROUND AND AIM

Searching for alternative therapies that are effective, safe and less expensive of those currently used for ulcerative colitis, we investigated the efficacy of a polyphenol extract from apple in rat colitis.

METHODS

Rats with trinitrobenzensulphonic acid-induced colitis were treated daily with rectal administration of apple polyphenols 10(-4) M for 14 days. COX-2, TNF-α, tissue transglutaminase and calpain in colon mucosa samples were assessed by reverse transcription-polymerase chain reaction and western blot analyses. To ascertain the role of tissue transglutaminase in mucosal healing, wounded rat fibroblasts were incubated with cystamine (a tissue transglutaminase activity inhibitor).

RESULTS

Colitis was associated with increased COX-2, TNF-α, calpain, and tissue transglutaminase mRNA. The protein expression of COX-2, TNF-α and calpain was increased whilst tissue transglutaminase was decreased. Apple extract treatment reduced the severity of colitis (p<0.05) and restored all the considered biomarkers at the baseline level. Apple polyphenols reduced the degradation of tissue transglutaminase protein occurring through calpain action. Apple polyphenols-treated wounded fibroblast recovered within 24h showing intense immunoreactivity for tissue transglutaminase.

CONCLUSION

The efficacy of apple extract is mediated by its effects on COX-2 and TNF-α. The unbalance between calpain and tissue transglutaminase may play a role in colonic damage and future therapeutic interventions in ulcerative colitis can target this mechanisms.

Inflammatory bowel disease: role of diet, microbiota, life style

Inflammatory bowel disease (IBD) encompassed several chronic inflammatory disorders leading to damage of the gastrointestinal tract (GI). The 2 principal forms of these disorders are ulcerative colitis (UC) and Crohn disease (CD). Bacteria are involved in the etiology of IBD, and the genetic susceptibility, environmental factors, and lifestyle factors can affect the individual's predisposition to IBD. The review discusses the potential role of environmental factors such as diet and microbiota as well as genetics in the etiology of IBD. It is suggested that microbial ecosystem in the human bowel colonizing the gut in many different microhabitats can be influence by diet, leading to formation of metabolic processes that are essential form the bowel metabolism.

Lactobacillus paracasei and Lactobacillus plantarum strains downregulate proinflammatory genes in an ex vivo system of cultured human colonic mucosa

Significant health benefits have been demonstrated for certain probiotic strains through intervention studies; however, there is a shortage of experimental evidence relative to the mechanisms of action. Here, noninvasive experimental procedure based on a colon organ culture system has been used that, in contrast to most experimental in vitro models reported, can preserve natural immunohistochemical features of the human mucosa. This system has been used to test whether commensal lactobacilli (Lactobacillus paracasei BL23, Lactobacillus plantarum 299v and L. plantarum 299v (A(-))) were able to hinder inflammation-like signals induced by phorbol 12-myristate 13-acetate (PMA)/ionomycin (IO). Whole genome microarrays have been applied to analyze expression differences, from which mRNA markers could be inferred to monitor the effect of putative probiotic strains under such conditions. Regarding the gene expression, PMA/IO treatment induced not only interleukin (IL)-2 and interferon gamma (IFN-γ), as expected, but also other relevant genes related to immune response and inflammation, such as IL-17A, chemokine (C-X-C motif) ligand (CXCL) 9 and CXCL11. The ex vivo culturing did not modify the pattern of expression of those genes or others related to inflammation. Interestingly, this study demonstrated that lactobacilli downregulated those genes and triggered a global change of the transcriptional profile that indicated a clear homeostasis restoring effect and a decrease in signals produced by activated T cells.

Transit time affects the community stability of Lactobacillus and Bifidobacterium species in an in vitro model of human colonic microbiotia

Retention time, which is analogous to transit time, is an index for bacterial stability in the intestine. Its consideration is of particular importance to optimize the delivery of probiotic bacteria in order to improve treatment efficacy. This study aims to investigate the effect of retention time on Lactobacilli and Bifidobacteria stability using an established in vitro human colon model. Three retention times were used: 72, 96, and 144 h. The effect of retention time on cell viability of different bacterial populations was analyzed with bacterial plate counts and PCR. The proportions of intestinal Bifidobacteria, Lactobacilli, Enterococci, Staphylococci and Clostridia populations, analyzed by plate counts, were found to be the same as that in human colonic microbiota. Retention time in the human colon affected the stability of Lactobacilli and Bifidobacteria communities, with maximum stability observed at 144 h. Therefore, retention time is an important parameter that influences bacterial stability in the colonic microbiota. Future clinical studies on probiotic bacteria formulations should take into consideration gastrointestinal transit parameters to improve treatment efficacy.

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.

Butyrate attenuates lipopolysaccharide-induced inflammation in intestinal cells and Crohn's mucosa through modulation of antioxidant defense machinery

Oxidative stress plays an important role in the pathogenesis of inflammatory bowel disease (IBD), including Crohn's disease (CrD). High levels of Reactive Oxygen Species (ROS) induce the activation of the redox-sensitive nuclear transcription factor kappa-B (NF-κB), which in turn triggers the inflammatory mediators. Butyrate decreases pro-inflammatory cytokine expression by the lamina propria mononuclear cells in CrD patients via inhibition of NF-κB activation, but how it reduces inflammation is still unclear. We suggest that butyrate controls ROS mediated NF-κB activation and thus mucosal inflammation in intestinal epithelial cells and in CrD colonic mucosa by triggering intracellular antioxidant defense systems. Intestinal epithelial Caco-2 cells and colonic mucosa from 14 patients with CrD and 12 controls were challenged with or without lipopolysaccaride from Escherichia Coli (EC-LPS) in presence or absence of butyrate for 4 and 24 h. The effects of butyrate on oxidative stress, p42/44 MAP kinase phosphorylation, p65-NF-κB activation and mucosal inflammation were investigated by real time PCR, western blot and confocal microscopy. Our results suggest that EC-LPS challenge induces a decrease in Gluthation-S-Transferase-alpha (GSTA1/A2) mRNA levels, protein expression and catalytic activity; enhanced levels of ROS induced by EC-LPS challenge mediates p65-NF-κB activation and inflammatory response in Caco-2 cells and in CrD colonic mucosa. Furthermore butyrate treatment was seen to restore GSTA1/A2 mRNA levels, protein expression and catalytic activity and to control NF-κB activation, COX-2, ICAM-1 and the release of pro-inflammatory cytokine. In conclusion, butyrate rescues the redox machinery and controls the intracellular ROS balance thus switching off EC-LPS induced inflammatory response in intestinal epithelial cells and in CrD colonic mucosa.

Differential targeting of the E-Cadherin/β-Catenin complex by gram-positive probiotic lactobacilli improves epithelial barrier function

The intestinal ecosystem is balanced by dynamic interactions between resident and incoming microbes, the gastrointestinal barrier, and the mucosal immune system. However, in the context of inflammatory bowel diseases (IBD), where the integrity of the gastrointestinal barrier is compromised, resident microbes contribute to the development and perpetuation of inflammation and disease. Probiotic bacteria have been shown to exert beneficial effects, e.g., enhancing epithelial barrier integrity. However, the mechanisms underlying these beneficial effects are only poorly understood. Here, we comparatively investigated the effects of four probiotic lactobacilli, namely, Lactobacillus acidophilus, L. fermentum, L. gasseri, and L. rhamnosus, in a T84 cell epithelial barrier model. Results of DNA microarray experiments indicating that lactobacilli modulate the regulation of genes encoding in particular adherence junction proteins such as E-cadherin and β-catenin were confirmed by quantitative reverse transcription-PCR (qRT-PCR). Furthermore, we show that epithelial barrier function is modulated by Gram-positive probiotic lactobacilli via their effect on adherence junction protein expression and complex formation. In addition, incubation with lactobacilli differentially influences the phosphorylation of adherence junction proteins and the abundance of protein kinase C (PKC) isoforms such as PKCδ that thereby positively modulates epithelial barrier function. Further insight into the underlying molecular mechanisms triggered by these probiotics might also foster the development of novel strategies for the treatment of gastrointestinal diseases (e.g., IBD).

The impact of perinatal immune development on mucosal homeostasis and chronic inflammation

The mucosal surfaces of the gut and airways have important barrier functions and regulate the induction of immunological tolerance. The rapidly increasing incidence of chronic inflammatory disorders of these surfaces, such as inflammatory bowel disease and asthma, indicates that the immune functions of these mucosae are becoming disrupted in humans. Recent data indicate that events in prenatal and neonatal life orchestrate mucosal homeostasis. Several environmental factors promote the perinatal programming of the immune system, including colonization of the gut and airways by commensal microorganisms. These complex microbial-host interactions operate in a delicate temporal and spatial manner and have an important role in the induction of homeostatic mechanisms.