Live probiotic Bifidobacterium lactis bacteria inhibit the toxic effects induced by wheat gliadin in epithelial cell culture

Human organoids and organ-on-chips in coeliac disease research

Coeliac disease (CeD) is an immune-mediated disorder characterised by gluten-triggered inflammation and damage in the small intestine, with lifelong gluten-free diet (GFD) as the only treatment. It is a multifactorial disease, involving genetic and environmental susceptibility factors, and its complexity and lack of comprehensive human model systems have hindered understanding of its pathogenesis and development of new treatments. Therefore, it is crucial to establish systems that recapitulate patient genetic background and the interactions between the small intestinal epithelial barrier, immune cells, and environment that contribute to CeD. In this review, we discuss disease complexity, recent advances in stem cell biology, organoids, tissue co-cultures, and organ-on-chip (OoC) systems that facilitate the development of comprehensive human model systems, and model applications in preclinical studies of potential treatments.

Vitamin D: An Essential Nutrient in the Dual Relationship between Autoimmune Thyroid Diseases and Celiac Disease-A Comprehensive Review

Autoimmune thyroid diseases (AITD) are among the most frequent autoimmune disorders, with a multifactorial etiology in which both genetic and environmental determinants are probably involved. Celiac disease (CeD) also represents a public concern, given its increasing prevalence due to the recent improvement of screening programs, leading to the detection of silent subtypes. The two conditions may be closely associated due to common risk factors, including genetic setting, changes in the composition and diversity of the gut microbiota, and deficiency of nutrients like vitamin D. This comprehensive review discussed the current evidence on the pivotal role of vitamin D in modulating both gut microbiota dysbiosis and immune system dysfunction, shedding light on the possible relevance of an adequate intake of this nutrient in the primary prevention of AITD and CeD. While future technology-based strategies for proper vitamin D supplementation could be attractive in the context of personalized medicine, several issues remain to be defined, including standardized assays for vitamin D determination, timely recommendations on vitamin D intake for immune system functioning, and longitudinal studies and randomized controlled trials to definitely establish a causal relationship between serum vitamin D levels and the onset of AITD and CeD.

Potential therapeutic options for celiac Disease: An update on Current evidence from Gluten-Free diet to cell therapy

Celiac disease (CD) is a chronic autoimmune enteropathy and multifactorial disease caused by inappropriate immune responses to gluten in the small intestine. Weight loss, anemia, osteoporosis, arthritis, and hepatitis are among the extraintestinal manifestations of active CD. Currently, a strict lifelong gluten-free diet (GFD) is the only safe, effective, and available treatment. Despite the social burden, high expenses, and challenges of following a GFD, 2 to 5 percent of patients do not demonstrate clinical or pathophysiological improvement. Therefore, we need novel and alternative therapeutic approaches for patients. Innovative approaches encompass a broad spectrum of strategies, including enzymatic degradation of gluten, inhibition of intestinal permeability, modulation of the immune response, inhibition of the transglutaminase 2 (TG2) enzyme, blocking antigen presentation by HLA-DQ2/8, and induction of tolerance. Hence, this review is focused on comprehensive therapeutic strategies ranging from dietary approaches to novel methods such as antigen-based immunotherapy, cell and gene therapy, and the usage of nanoparticles for CD treatment.

Probiotics to Prevent Celiac Disease and Inflammatory Bowel Diseases

The incidence of chronic inflammatory diseases (CIDs) is dramatically increasing in the developed world, resulting in an increased burden of disease in childhood. Currently, there are limited effective strategies for treating or preventing these conditions. To date, myriads of cross-sectional studies have described alterations in the composition of the gut microbiota in a variety of disease states, after the disease has already occurred. We suggest that to mechanically link these microbiome changes with disease pathogenesis, a prospective cohort design is needed to capture changes that precede or coincide with disease onset and symptoms. In addition, these prospective studies must integrate microbiological, metagenomic, meta transcriptomic and metabolomic data with minimal and standardized clinical and environmental metadata that allow to correctly compare and interpret the results of the analysis of the human microbiota in order to build a system-level model of the interactions between the host and the development of the disease. The creation of new biological computational models thus constructed will allow us to finally move from the detection of simple elements of "association" to the identification of elements of real "causality" allowing to provide a mechanistic approach to the exploration of the development of CIDs.This can only be done when these diseases are studied as complex biological networks. In this chapter we discuss the current knowledge regarding the contribution of the microbiome to CID in childhood, focusing on celiac disease and inflammatory bowel disease, with the overall aim of identifying pathways to shift research from descriptive to mechanistic approaches. We then examine how some components of the microbiota, through epigenetic reprogramming, can start the march from genetic predisposition to clinical expression of CIDs, thus opening up new possibilities for intervention, through microbiota therapy targeting the manipulation of the composition and function of the microbiota, for future applications of precision medicine and primary prevention.

Bifidobacterium mechanisms of immune modulation and tolerance

Bifidobacterium is a widely distributed commensal bacterial genus that displays beneficial pro-homeostatic and anti-inflammatory immunomodulatory properties. Depletion or absence of Bifidobacterium in humans and model organisms is associated with autoimmune responses and impaired immune homeostasis. At the cellular level, Bifidobacterium upregulates suppressive regulatory T cells, maintains intestinal barrier function, modulates dendritic cell and macrophage activity, and dampens intestinal Th2 and Th17 programs. While there has been a large volume of literature characterizing the probiotic properties of various Bifidobacterial species, the likely multifactorial mechanisms underlying these effects remain elusive, in particular, its immune tolerogenic effect. However, recent work has shed light on Bifidobacterium surface structural polysaccharide and protein elements, as well as its metabolic products, as commensal mediators of immune homeostasis. This review aims to discuss several mechanisms Bifidobacterium utilizes for immune modulation as well as their indirect impact on the regulation of gut microbiome structure and function, from structural molecules to produced metabolites. These mechanisms are pertinent to an increasingly networked understanding of immune tolerance and homeostasis in health and disease.

The Role of Intestinal Microbiota in Celiac Disease and Further Therapeutic Perspectives

Celiac disease (CD) is an immune-mediated enteropathy caused by exposure to gluten and related prolamins in genetically susceptible individuals. It is a complex genetic disorder with multiple contributing genes. Linkage studies have identified several genomic regions that probably contain CD susceptibility genes. The most important genetic factors are HLA-DQ2 and DQ8. Several known environmental triggers promote the onset of CD at any age after gluten introduction in individuals with a genetic background, such as viral infections and intestinal dysbiosis. Recent publications have described the interference of the intestinal microbiome in gluten metabolism, modulation of local immune reactions, and in maintaining normal gut permeability. These results have promoted further lines of research on the benefit of probiotic administration to prevent disease onset or alleviate clinical symptoms along with a gluten-free diet (GFD). The relationship between gut microbiome changes and the onset of CD is incompletely understood, still being the subject of current research. This narrative review analyzes the interplay between environmental factors, intestinal microbiome alterations, and the course of CD. Furthermore, this review sets out to discuss if modulation of intestinal microflora with pre- and probiotics along with a GFD could represent a reliable therapeutic target for celiac patients.

Impact of probiotics on gut microbiota composition and clinical symptoms of coeliac disease patients following gluten-free diet

Coeliac disease (CD) is associated with alterations in gut microbiota composition. This study evaluated the effects of probiotics on gut microbiota composition and clinical symptoms of treated CD patients. In this double-blind, placebo-controlled trial study, 31 CD patients that were randomly classified as probiotics (n = 15) and placebo (n = 16) groups received 109 colony-forming units/capsule for 12 weeks. Fecal samples were collected before and after probiotics, or placebo administration and the changes in intestinal microbiota were assessed by quantitative real-time PCR. Probiotic administration improved the patients' clinical symptoms when compared to the placebo group. Fatigue score was significantly reduced by the intake of probiotic supplements (P = 0.02). Except for Staphylococcus spp., the relative abundances of Bacteroidetes, Lactobacillus spp., Bifidobacterium spp., Clostridium cluster I, Enterobacteriaceae, and Firmicutes were higher in probiotics group. Accordingly, a 12-week multi-strain probiotic treatment regimen may modify the composition of intestinal microbiota and improve GI symptoms in CD patients.

The effects of probiotics on gastrointestinal symptoms and microbiota in patients with celiac disease: a systematic review and meta-analysis on clinical trials

Gluten-free diet (GFD) is the most effective method to manage celiac disease (CD). Many patients do not reach the complete symptom alleviation, even by strict GFD. Recent studies have reported inconsistent results regarding the beneficial benefits of taking probiotics. Therefore, we aimed to evaluate the effects of probiotics on gastrointestinal (GI) symptoms and the possible underlying causes in CD and celiac disease autoimmunity (CDA) patients. Databases, including PubMed, Scopus, Embase, Web of Science and Google Scholar, were searched for clinical trials published until July 2022 about assessing the effects of probiotics or synbiotics on CD or CDA patients. We collected data on GI symptoms, CD markers, inflammatory and immune responses, adverse events, and gut microbiota. A random effect meta-analysis was used to estimate the pooled standardized mean difference (SMD) and confidence interval (CI). We screened 7234 articles, of which 14 were included in the qualitative analysis and 5 in the quantitative analysis. Probiotics might alleviate GI symptoms, especially in the highly symptomatic patients, and improve immune response in CD and CDA patients. Results of the meta-analysis showed that probiotics increased the abundance of Bifidobacterium (SMD: 0.72, 95%CI (0.13, 1.30) and Lactobacillus (SMD: 0.49, 95%CI (0.18, 0.80) as compared with placebo. Probiotics did not increase the adverse events compared to the placebo. Probiotics might alleviate GI symptoms and immune response and improve dysbiosis in CD and CDA patients. However, high-quality clinical trials are needed to increase the level of evidence. Also, the most suitable combination of probiotics is yet to find.

A gluten degrading probiotic Bacillus subtilis LZU-GM relieve adverse effect of gluten additive food and balances gut microbiota in mice

Gluten accumulation damages the proximal small intestine and causes celiac disease (CeD) which has not been effectively treated except by using a gluten-free diet. In this study, strain Bacillus subtilis LZU-GM was isolated from Pakistani traditional fermented sourdough and could degrade 73.7% of gluten in 24 h in vitro. Strain LZU-GM was employed for practical application to investigate gluten degradation in mice models. The results showed that strain LZU-GM was colonized in mice and the survival rate was around 0.95 % (P < 0.0001). The gluten degradation was 3-fold higher in the small intestine of the strain LZU-GM treated mice group remaining 1511.96 ng/mL of gluten peptides than the untreated mice group (6500.38 ng/mL). Immunochemical analysis showed that gluten-treated mice established positive antigliadin antibodies (AGA) in serum (IgA, IgG, and anti-TG2 antibodies) as compared to the strain LZU-GM treatment group. Furthermore, the number of IFN-γ, TNF-α, IL-10, and COX-2 cells decrease in the lamina propria of the strain LZU-GM treatment group (P < 0.0001). Microbial community bar plot analysis showed that Lactobacillus, Dubosiella, and Enterococcus genera were restored and stabilized in the LZU-GM treatment group while Blautia and Ruminococcus were found lower. The oral gavage of probiotic strain LZU-GM might be useful for gluten metabolism in the intestine during digestion and would be a long-term dietary treatment for CeD management.

Protective effects of Acetobacter ghanensis against gliadin toxicity in intestinal epithelial cells with immunoregulatory and gluten-digestive properties

PURPOSE

The aim of this study was to establish whether Acetobacter ghanensis, the probiotic characteristics of which were evaluated previously, attenuates gliadin-induced toxicity in intestinal epithelial cells with gluten-digestive and immunoregulatory properties.

METHODS

A co-culture model of human intestinal epithelial cell (Caco-2) monolayers on top of peripheral blood mononuclear cells (PBMCs) obtained from patients with celiac disease (CD) was established. The gluten-digestive properties of A. ghanensis were determined by checking bacterial growth in a medium containing gluten as the main nitrogen source. The mRNA levels of genes encoding TJ-associated proteins were measured by quantitative real-time PCR (qRT-PCR). The concentrations of IL-6 and TNFα were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

We found that PT-gliadin disrupted intestinal barrier integrity by modulating the expression of TJ-associated genes encoding zonulin (increased by ~ 60%), zonula occludens-1 (ZO-1) (decreased by ~ 22%), and occludin (decreased by ~ 28%) in Caco-2 cells. Furthermore, PT-gliadin treatment in Caco-2 cells was associated with increased concentrations of IL-6 (~ 1.6-fold) and TNFα (~ twofold) from PBMCs. These modulatory effects of PT-gliadin, however, were suppressed when Caco-2 cells were subjected to A. ghanensis in the presence of PT-gliadin. As a factor underlying these protective effects, we showed that A. ghanensis could digest gluten peptides.

CONCLUSIONS

To our knowledge, the current study is the first to demonstrate that A. ghanensis improves intestinal barrier functions by attenuating the modulatory effects of PT-gliadin with immunoregulatory and gluten-digestive properties.

Restorative effects of Acetobacter ghanensis on the pathogenicity of gliadin-induced modulation of tight junction-associated gene expression in intestinal epithelial cells

Background/Aim: At present, a gluten-free diet is the only efficient way to treat celiac disease (CD). The development of novel approaches to lessen or counteract the pathogenic effects of gluten remains crucial for the treatment of CD. The aim in this investigation was to examine the restorative effects of Acetobacter ghanensis as a novel probiotic against gliadin-induced modulation in the barrier integrity of an intestinal epithelial cell (IEC) model (Caco-2). Methods: Fully differentiated Caco-2 cell monolayers were subjected to enzymatically digested gliadin with a pepsin and trypsin (PT) in the presence or absence of A. ghanensis for 90 min. The relative amounts of zonulin, zonula occludens-1 (ZO-1), claudin-1, and occludin mRNA expression were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Transepithelial electrical resistance (TEER) was evaluated to monitor the barrier integrity of cell monolayers. Statistical analyses were carried out using one- or two-way ANOVA followed by Tukey’s post-hoc analysis for multiple pairwise comparisons. Results: A significant upregulation (4.7-fold) of zonulin was noted in the PT-gliadin treated Caco-2 cells in comparison with the untreated controls (P<0.001). Conversely, gliadin-induced zonulin expression was markedly downregulated in the Caco-2 cells following exposure to A. ghanensis in the presence of PT-gliadin (P<0.001). Furthermore, prominent decreases in the mRNA expression levels of ZO-1 (45%) and occludin (40%) were seen in the PT-gliadin exposed Caco-2 cells compared to the untreated control cells (P<0.001). PT-gliadin in the Caco-2 cells did not significantly alter the mRNA levels of claudin-1 (P=0.172). Similarly to zonulin expression, the decreasing effect of PT-gliadin on ZO-1 was completely attenuated in the PT-gliadin-administrated Caco-2 cells following exposure to A. ghanensis (P<0.001). Conclusion: A. ghanensis restored the pathogenicity of PT-gliadin on intestinal barrier integrity.

Celiac Disease: Disease Models in Understanding Pathogenesis and Search for Therapy

Celiac disease is a complex polygenic systemic disorder caused by dietary gluten exposure that selectively occurs in genetically susceptible people. The potential celiac disease is defined by the presence of celiac disease-specific antibodies and compatible human leukocyte antigen but without histological abnormalities in duodenal biopsies. At present, the only treatment is lifelong adherence to a gluten-free diet. Despite its effectiveness, the diet is difficult to maintain due to its cost, availability of gluten-free foods, and hidden gluten. The need to develop non-dietary treatment methods is widely recognized, but this is prevented by the absence of a pathophysiologically relevant preclinical model. Nonetheless, in vitro and in vivo models have made it possible to investigate the mechanisms of the disease and develop new treatment approaches: The use of foods with neutralized gluten, microbiota correction, cocktails of specific endoproteinase, polymer gluten binders, specific inhibitors of transglutaminases and inflammatory cytokines, and a vaccine based on allergen-specific therapy.

Celiac Disease and Neurological Manifestations: From Gluten to Neuroinflammation

Celiac disease (CD) is a complex multi-organ disease with a high prevalence of extra-intestinal involvement, including neurological and psychiatric manifestations, such as cerebellar ataxia, peripheral neuropathy, epilepsy, headache, cognitive impairment, and depression. However, the mechanisms behind the neurological involvement in CD remain controversial. Recent evidence shows these can be related to gluten-mediated pathogenesis, including antibody cross-reaction, deposition of immune-complex, direct neurotoxicity, and in severe cases, vitamins or nutrients deficiency. Here, we have summarized new evidence related to gut microbiota and the so-called "gut-liver-brain axis" involved in CD-related neurological manifestations. Additionally, there has yet to be an agreement on whether serological or neurophysiological findings can effectively early diagnose and properly monitor CD-associated neurological involvement; notably, most of them can revert to normal with a rigorous gluten-free diet. Moving from a molecular level to a symptom-based approach, clinical, serological, and neurophysiology data might help to disentangle the many-faceted interactions between the gut and brain in CD. Eventually, the identification of multimodal biomarkers might help diagnose, monitor, and improve the quality of life of patients with "neuroCD".

Probiotics and gastrointestinal diseases

During the past decades, scientists have discovered the intimate role of the gut microbiome in human health, and since then, several papers have been published to investigate if the use of biotics (probiotics, prebiotics, synbiotics, and postbiotics) may have a beneficial impact on human health both in treatment and prevention. We now ask ourselves whether we have reached the finish line or just a new starting point, as the evidence supporting the use of biotics in several conditions still needs a lot of work. Many questions remain unanswered today because the evidence differs depending on the indication, used strain, and amount and duration of administration. Herein we will summarize the evidence on probiotics in some gastrointestinal diseases such as infantile colic, functional abdominal pain disorders, celiac disease, acute gastroenteritis, inflammatory bowel disease, and Helicobacter pylori infection.

Novel Drug Therapeutics in Celiac Disease: A Pipeline Review

Celiac disease (CeD) is a chronic, autoimmune systemic disorder triggered by the ingestion of gluten, a protein found in foods such as wheat, rye, and barley. The only effective treatment for CeD is complete removal of gluten from the diet. A strict gluten-free diet (GFD) results in symptomatic, serologic, and histologic remission in most patients. However, GFD may fail to induce clinical or histologic improvement and some patients may alternatively have difficulty strictly adhering to the GFD for other reasons. Despite this, there are currently no FDA-approved drugs for the treatment of CeD. The complex pathogenic process of CeD is becoming increasingly studied and better understood, enabling the identification of various targets for future therapies. Mechanisms under evaluation include probiotics, digestion of peptides, gluten sensitization, tight junction modulation, deamidation, and immune targets. Multiple investigational drugs are in the pipeline, and several drug candidates have entered late-phase clinical trials. Indeed, current and future studies are needed to target specific etiological mechanisms and provide an alternative to GFD alone. This review provides a broad overview of the various investigative treatment approaches for CeD, summarizing the latest progress in the pipeline.

Dietary supplements for intestinal inflammation

Intestinal inflammation leads to various chronic diseases, collectively known as inflammatory bowel disease (IBD). IBD mainly affects the large intestine, but it can also affect the gastrointestinal tract as a whole. Its major symptoms are pain, diarrhea, and weight loss, and it is usually associated with deficiencies of both macro- and micronutrients. Unluckily, after some time the body develops resistance against the already available drugs: thus, many patients fail to maintain remission, which is achieved in less than 50% of cases. Diet is a major determinant of gut inflammation. An unbalanced diet can affect the gut microbiota and cause dysbiosis, which is related to a dysregulated host immune response. The Mediterranean Diet its renowned for its anti-inflammatory effects and for preventing dysbiosis. In order to improve management and treatment of intestinal inflammatory diseases, it should become common practice to integrate the patient's diet with dietary supplements with anti-inflammatory effects (probiotics, butyrate, phosphatidylcholine, lactoferrin, palmitoylethanolamide, silymarin, and omega 3), which maintain the stability of the intestinal microbial cohort and strengthen the mucosal barrier, thus preventing or soothing IBD symptoms. Dietary supplements may help fight the high costs, the adverse side effects, and the recurrent relapses typical of drug use.

Screening of Spore-Forming Bacteria with Probiotic Potential in Pristine Algerian Caves

The interest and exploration of biodiversity in subsurface ecosystems have increased significantly during the last 2 decades. The aim of this study was to investigate the in vitro probiotic properties of spore-forming bacteria isolated from deep caves. Two hundred fifty spore-forming microbes were enriched from sediment samples from 10 different pristine caves in Algeria at different depths. Isolates showing nonpathogenic profiles were screened for their potential to produce digestive enzymes (gliadinase and beta-galactosidase) in solid and liquid media, respectively. Different probiotic potentialities were studied, including (i) growth at 37°C, (ii) survival in simulated gastric juice, (iii) survival in simulated intestinal fluid, and (iv) antibiotic sensitivity and cell surface properties. The results showed that out of 250 isolates, 13 isolates demonstrated nonpathogenic character, probiotic potentialities, and ability to hydrolyze gliadin and lactose in solution. These findings suggest that a selection of cave microbes might serve as a source of interesting candidates for probiotics.

IMPORTANCE Previous microbial studies of subsurface ecosystems like caves focused mainly on the natural biodiversity in these systems. So far, only a few studies focused on the biotechnological potential of microbes in these systems, focusing in particular on their antibacterial potential, antibiotic production, and, to some extent, enzymatic potential. This study explores whether subsurface ecosystems can serve as an alternative source for microbes relevant to probiotics. The research focused on the ability of cave microbes to degrade two substrates (lactose and gliadin) that cause common digestive disorders. Since these enzymes may prove to be useful in food processing and in reducing the effect of lactose and gliadin digestion within intolerant patients, isolation of microbes such as in this study may expand the possibilities of developing alternative strategies to deal with these intolerances.

Influence of Gluten-Free Diet on Gut Microbiota Composition in Patients with Coeliac Disease: A Systematic Review

The aim of this study was to assess the changes in microbiota composition during a gluten-free diet (GFD) in coeliac disease (CD) patients. The systematic search followed databases such as PUBMED (MEDLINE), SCOPUS, WEB OF SCIENCE and EMBASE. Out of 843 initially screened papers, a total number of 13 research papers were included. A total of 212 patients with CD on GFD, in comparison to 174 healthy individuals and 176 untreated patients with CD, were examined. Analysis of the microbial community based primarily on faecal samples and duodenal biopsies. Bifidobacterium was noticed to be less abundant in the study group than in both control groups, while the abundance of Bacteroides was more numerous in the group of CD patients on GFD. Staphylococcaceae prevailed in untreated CD patients. Despite the fact that the GFD was not able to fully restore commensal microorganism abundance, the treatment was associated with the greater abundance of selected beneficial bacteria and lower presence of pathogenic bacteria associated with worsening of CD symptoms.

Review article: therapeutic targets for the pharmacologic management of coeliac disease-the future beyond a gluten-free diet

BACKGROUND

Coeliac disease (CeD) is an immune-mediated small bowel enteropathy resulting from dietary gluten exposure. Presently, the only effective treatment is adoption of a gluten-free diet (GFD), although strict adherence is challenging to maintain, and inadvertent gluten exposures are inevitable for most patients. Hence, there is substantial interest in drug development in CeD and multiple novel therapies are under investigation.

AIMS

To review existing and upcoming clinical trial programmes for pharmacologic agents for CeD.

METHODS

A narrative review was performed, informed by a search of MEDLINE, Embase, the Cochrane CENTRAL Library and clinicaltrials.gov.

RESULTS

We summarise the pathophysiology of CeD and the specific steps that are potentially amenable to pharmacologic treatment. We evaluate the evidence supporting existing and future drug targets, including trials of peptidases, gluten sequestrants, tight junction regulators, anti-transglutaminase 2 therapies, immune tolerizing agents, advanced biologics and small molecules, and microbiome-targeted strategies. We highlight unique considerations for conducting CeD trials, including identifying appropriate study populations, assessing results in the context of a gluten challenge, and interpreting CeD-specific clinical and histologic outcomes. Understanding these factors is crucial for accurately appraising the evidence. Finally, we outline what the future of CeD therapy may hold with the introduction of pharmacotherapies.

CONCLUSIONS

There is a need for pharmacologic options for CeD, either used adjunctively with a GFD for accidental or intentional gluten exposures or for refractory disease. Multiple promising agents are in development, and these trials are likely to lead to approvals for the first generation of pharmacologic agents for CeD within the next 5 years.

Molecular interactions between the intestinal microbiota and the host

The intestine is the most densely colonized region of the body, inhabited by a diverse community of microbes. The functional significance of the intestinal microbiota is not yet fully understood, but it is known that the microbiota is implicated in numerous physiological processes of the host, such as metabolism, nutrition, the immune system, and regulation of behavior and mood. This article reviews recent findings on how bacteria of the intestinal microbiota interact with the host.

Microbiota‐microbiota and microbiota‐host interactions are mediated by direct cell contact and by metabolites either produced by bacteria or produced by the host or the environment and metabolized by bacteria. Among them are short‐chain fatty, including butyrate, propionate, and acetate. Other examples include polyamines, linoleic acid metabolites, tryptophan metabolites, trimethylamine‐N‐oxide, vitamins, and secondary bile acids. These metabolites are involved in regulating the cell cycle, neurobiological signaling, cholesterol and bile acid metabolism, immune responses, and responses to antioxidants. Understanding the host‐microbiota pathways and their modulation will allow the identification of individualized therapeutic targets for many diseases. This overview helps to facilitate and promote further research in this field.

Summary of Probiotic Potential of the Kefir for the Prevention and Alleviation of Functional GI Diseases

Background:

Functional Gastrointestinal (GI) disease is a term that refers to a range of disease conditions involving chronic diarrhea, irritable bowel syndrome, constipation, inflammatory bowel disease (IBD), and lactose intolerance. Statistical reports have documented >40% of the world's population is being afflicted by functional GI disorders. Consequences of frequent intake of antibiotics include mortality of gut microflora, antibiotic-associated diarrhea, the establishment of antibiotic resistance, and inference with healthy bodily functions. To overcome the harms of antibiotics, studies are being conducted to determine the potential of probiotics as alternatives to antibiotics.

Aim of Study:

The purpose of constructing this literature review is to outline the potential attributes of Kefir and to assess the solitary efficiency of this beverage in the amelioration of GI disease conditions.

Methodology:

Extraction of data entailed digging of literature hubs including PubMed, PubMed Central, Research Gate, Science Direct, and Google Scholar, employing a different combination of keywords to retrieve substantial details. Selection criteria of the articles involved the published reports of preceding 10 years (2012-2021) that exhibited relevancy with the topic

Conclusion:

Kefir grains having different origins provide a distinct array of antimicrobial spectrums and are found to be effective against different pathogens. IBDs, diarrheal sicknesses, and constipation can be alleviated by the consumption of this beverage. Moreover, the probioticantibiotic combination is also essential for the mitigation of several diseases. The synergistic impact of several microbial strains is vital for the treatment of celiac disease. Lactose maldigestion can be relieved by the consumption of kefir having β-galactosidase enzyme activity.

Next generation strategies to recover immunological tolerance in celiac disease

Celiac disease (CD) is an autoimmune disease that occurs in genetically predisposed individuals following the ingestion of gluten. Its prevalence is rising worldwide. A gluten-free (GF) diet is mandatory for the management of CD. However, several issues persist regarding the nutritional quality of GF products. Importantly, deep knowledge about the pathogenic mechanisms in CD highlights the central role of CD4⁺ T cell-mediated immunity in CD. Furthermore, intestinal T regulatory cells are functional in CD, but cytokines such as IL-15, produced under inflammatory conditions, hamper their activity. This paves the way for the development of immunomodulatory strategies to the GF diet. From this perspective, microbiological approaches were considered able to modulate the gluten-specific immune response. Interestingly, gliadin peptide-based immunotherapy to abolish the inflammatory CD4⁺T cell-mediated response has been explored in CD patients. Furthermore, different biotechnological approaches based on the use of chemically/enzymatically modified gluten molecules have been proved effective in different models of CD. However, the choice of the right age in infants to introduce the antigen and thus induce tolerance still remains an important issue to solve. Addressing all these points should help to design an effective intervention strategy for preventing CD.

The role of the microbiome in gastrointestinal inflammation

The microbiome plays an important role in maintaining human health. Despite multiple factors being attributed to the shaping of the human microbiome, extrinsic factors such diet and use of medications including antibiotics appear to dominate. Mucosal surfaces, particularly in the gut, are highly adapted to be able to tolerate a large population of microorganisms whilst still being able to produce a rapid and effective immune response against infection. The intestinal microbiome is not functionally independent from the host mucosa and can, through presentation of microbe-associated molecular patterns (MAMPs) and generation of microbe-derived metabolites, fundamentally influence mucosal barrier integrity and modulate host immunity. In a healthy gut there is an abundance of beneficial bacteria that help to preserve intestinal homoeostasis, promote protective immune responses, and limit excessive inflammation. The importance of the microbiome is further highlighted during dysbiosis where a loss of this finely balanced microbial population can lead to mucosal barrier dysfunction, aberrant immune responses, and chronic inflammation that increases the risk of disease development. Improvements in our understanding of the microbiome are providing opportunities to harness members of a healthy microbiota to help reverse dysbiosis, reduce inflammation, and ultimately prevent disease progression.

Intestinal Microbiota in Common Chronic Inflammatory Disorders Affecting Children

The incidence and prevalence rate of chronic inflammatory disorders is on the rise in the pediatric population. Recent research indicates the crucial role of interactions between the altered intestinal microbiome and the immune system in the pathogenesis of several chronic inflammatory disorders in children, such as inflammatory bowel disease (IBD) and autoimmune diseases, such as type 1 diabetes mellitus (T1DM) and celiac disease (CeD). Here, we review recent knowledge concerning the pathogenic mechanisms underlying these disorders, and summarize the facts suggesting that the initiation and progression of IBD, T1DM, and CeD can be partially attributed to disturbances in the patterns of composition and abundance of the gut microbiota. The standard available therapies for chronic inflammatory disorders in children largely aim to treat symptoms. Although constant efforts are being made to maximize the quality of life for children in the long-term, sustained improvements are still difficult to achieve. Additional challenges are the changing physiology associated with growth and development of children, a population that is particularly susceptible to medication-related adverse effects. In this review, we explore new promising therapeutic approaches aimed at modulation of either gut microbiota or the activity of the immune system to induce a long-lasting remission of chronic inflammatory disorders. Recent preclinical studies and clinical trials have evaluated new approaches, for instance the adoptive transfer of immune cells, with genetically engineered regulatory T cells expressing antigen-specific chimeric antigen receptors. These approaches have revolutionized cancer treatments and have the potential for the protection of high-risk children from developing autoimmune diseases and effective management of inflammatory disorders. The review also focuses on the findings of studies that indicate that the responses to a variety of immunotherapies can be enhanced by strategic manipulation of gut microbiota, thus emphasizing on the importance of proper interaction between the gut microbiota and immune system for sustained health benefits and improvement of the quality of life of pediatric patients.

Probiotics and gut health

BACKGROUND

Gut microbiota is a complex ecosystem of bacteria, viruses, archea, protozoa and yeasts in our intestine. It has several functions maintaining human body equilibrium. Microbial " dysbiosis " can be responsible for several gastrointestinal diseases.

METHODS

to build a narrative review we performed a Pubmed, Medline, EMBASE search for English language papers, reviews, meta-analyses, case series, and randomized controlled trials (RCTs) by keywords and their associations: gut microbiota, dysbiosis, gastrointestinal diseases, probiotics.

RESULTS

gut microbiota is altered in several gastrointestinal diseases with very different pathophysiology. They range from multi-factorial diseases such as irritable bowel syndrome (IBS), non-alcoholic fatty liver disease (NAFLD) and gastric and colorectal cancers, immunemediated such as celiac disease, inflammatory bowel diseases (IBD), antibioticrelated such as Clostridium Difficile infection (CDI). Microbial dysbiosis re-modulation by probiotics is feasible and safe in some of them.

CONCLUSIONS

gut microbial dysbiosis is statistically associated with several gastro-intestinal diseases, affecting their pathophysiology. Its reverse by probiotics has some promising evidences of efficacy.

Gluten-degrading bacteria: availability and applications

Gluten is a mixture of storage proteins in wheat and occurs in smaller amounts in other cereal grains. It provides favorable structure to bakery products but unfortunately causes disease conditions with increasing prevalence. In the human gastrointestinal tract, gluten is cleaved into proline and gluten rich peptides that are not degraded further. These peptides trigger immune responses that might lead to celiac disease, wheat allergy, and non-celiac gluten sensitivity. The main treatment option is a gluten-free diet. Alternatively, using enzymes or microorganisms with gluten-degrading properties might alleviate the disease. These components can be used during food production or could be introduced into the digestive tract as food supplements. In addition, natural food from the environment is known to enrich the microbial communities in gut and natural environmental microbial communities have high potential to degrade gluten. It remains to be investigated if food and environment-induced changes in the gut microbiome could contribute to the triggering of gluten-related diseases. KEY POINTS: • Wheat proteins, gluten, are incompletely digested in human digestive tract leading to gluten intolerance. • The only efficient treatment of gluten intolerance is life-long gluten-free diet. • Environmental bacteria acquired together with food could be source of gluten-degrading bacteria detoxifying undigested gluten peptides.

Selection of Gut-Resistant Bacteria and Construction of Microbial Consortia for Improving Gluten Digestion under Simulated Gastrointestinal Conditions

This work aimed to define the microbial consortia that are able to digest gluten into non-toxic and non-immunogenic peptides in the human gastrointestinal tract. Methods: 131 out of 504 tested Bacillus and lactic acid bacteria, specifically Bacillus (64), lactobacilli (63), Pediococcus (1), and Weissella (3), showed strong gastrointestinal resistance and were selected for their PepN, PepI, PepX, PepO, and PepP activities toward synthetic substrates. Based on multivariate analysis, 24 strains were clearly distinct from the other tested strains based on having the highest enzymatic activities. As estimated by RP-HPLC and nano-ESI–MS/MS, 6 cytoplasmic extracts out of 24 selected strains showed the ability to hydrolyze immunogenic epitopes, specifically 57–68 of α9-gliadin, 62–75 of A-gliadin, 134–153 of γ-gliadin, and 57–89 (33-mer) of α2-gliadin. Live and lysed cells of selected strains were combined into different microbial consortia for hydrolyzing gluten under gastrointestinal conditions. Commercial proteolytic enzymes (Aspergillusoryzae E1, Aspergillusniger E2, Bacillussubtilis Veron HPP, and Veron PS proteases) were also added to each microbial consortium. Consortium activity was evaluated by ELISA tests, RP-HPLC-nano-ESI–MS/MS, and duodenal explants from celiac disease patients. Results: two microbial consortia (Consortium 4: Lactiplantibacillus (Lp.) plantarum DSM33363 and DSM33364, Lacticaseibacillus (Lc.) paracasei DSM33373, Bacillussubtilis DSM33298, and Bacilluspumilus DSM33301; and Consortium 16: Lp. plantarum DSM33363 and DSM33364, Lc. paracasei DSM33373, Limosilactobacillusreuteri DSM33374, Bacillusmegaterium DSM33300, B.pumilus DSM33297 and DSM33355), containing commercial enzymes, were able to hydrolyze gluten to non-toxic and non-immunogenic peptides under gastrointestinal conditions. Conclusions: the results of this study provide evidence that selected microbial consortia could potentially improve the digestion of gluten in gluten-sensitive patients by hydrolyzing the immunogenic peptides during gastrointestinal digestion.

Contribution of Infectious Agents to the Development of Celiac Disease

The ingestion of wheat gliadin (alcohol-soluble proteins, an integral part of wheat gluten) and related proteins induce, in genetically predisposed individuals, celiac disease (CD), which is characterized by immune-mediated impairment of the small intestinal mucosa. The lifelong omission of gluten and related grain proteins, i.e., a gluten-free diet (GFD), is at present the only therapy for CD. Although a GFD usually reduces CD symptoms, it does not entirely restore the small intestinal mucosa to a fully healthy state. Recently, the participation of microbial components in pathogenetic mechanisms of celiac disease was suggested. The present review provides information on infectious diseases associated with CD and the putative role of infections in CD development. Moreover, the involvement of the microbiota as a factor contributing to pathological changes in the intestine is discussed. Attention is paid to the mechanisms by which microbes and their components affect mucosal immunity, including tolerance to food antigens. Modulation of microbiota composition and function and the potential beneficial effects of probiotics in celiac disease are discussed.

Anti-Inflammatory and Immunomodulatory Effects of Probiotics in Gut Inflammation: A Door to the Body

Hosting millions of microorganisms, the digestive tract is the primary and most important part of bacterial colonization. On one side, in cases of opportunistic invasion, the abundant bacterial population inside intestinal tissues may face potential health problems such as inflammation and infections. Therefore, the immune system has evolved to sustain the host-microbiota symbiotic relationship. On the other hand, to maintain host immune homeostasis, the intestinal microflora often exerts an immunoregulatory function that cannot be ignored. A field of great interest is the association of either microbiota or probiotics with the immune system concerning clinical uses. This microbial community regulates some of the host's metabolic and physiological functions and drives early-life immune system maturation, contributing to their homeostasis throughout life. Changes in gut microbiota can occur through modification in function, composition (dysbiosis), or microbiota-host interplays. Studies on animals and humans show that probiotics can have a pivotal effect on the modulation of immune and inflammatory mechanisms; however, the precise mechanisms have not yet been well defined. Diet, age, BMI (body mass index), medications, and stress may confound the benefits of probiotic intake. In addition to host gut functions (permeability and physiology), all these agents have profound implications for the gut microbiome composition. The use of probiotics could improve the gut microbial population, increase mucus-secretion, and prevent the destruction of tight junction proteins by decreasing the number of lipopolysaccharides (LPSs). When LPS binds endothelial cells to toll-like receptors (TLR 2, 4), dendritic cells and macrophage cells are activated, and inflammatory markers are increased. Furthermore, a decrease in gut dysbiosis and intestinal leakage after probiotic therapy may minimize the development of inflammatory biomarkers and blunt unnecessary activation of the immune system. In turn, probiotics improve the differentiation of T-cells against Th2 and development of Th2 cytokines such as IL-4 and IL-10. The present narrative review explores the interactions between gut microflora/probiotics and the immune system starting from the general perspective of a biological plausibility to get to the in vitro and in vivo demonstrations of a probiotic-based approach up to the possible uses for novel therapeutic strategies.

Gliadin Sequestration as a Novel Therapy for Celiac Disease: A Prospective Application for Polyphenols

Celiac disease is an autoimmune disorder characterized by a heightened immune response to gluten proteins in the diet, leading to gastrointestinal symptoms and mucosal damage localized to the small intestine. Despite its prevalence, the only treatment currently available for celiac disease is complete avoidance of gluten proteins in the diet. Ongoing clinical trials have focused on targeting the immune response or gluten proteins through methods such as immunosuppression, enhanced protein degradation and protein sequestration. Recent studies suggest that polyphenols may elicit protective effects within the celiac disease milieu by disrupting the enzymatic hydrolysis of gluten proteins, sequestering gluten proteins from recognition by critical receptors in pathogenesis and exerting anti-inflammatory effects on the system as a whole. This review highlights mechanisms by which polyphenols can protect against celiac disease, takes a critical look at recent works and outlines future applications for this potential treatment method.

Gut microbiota in Celiac Disease: microbes, metabolites, pathways and therapeutics

INTRODUCTION

Current evidence supports a vital role of the microbiota on health outcomes, with alterations in an otherwise healthy balance linked to chronic medical conditions like celiac disease (CD). Recent advances in microbiome analysis allow for unparalleled profiling of the microbes and metabolites. With the growing volume of data available, trends are emerging that support a role for the gut microbiota in CD pathogenesis.

AREAS COVERED

In this article, the authors review the relationship between factors such as genes and antibiotic exposure on CD onset and the intestinal microbiota. The authors also review other microbiota within the human body (like the oropharynx) that may play a role in CD pathogenesis. Finally, the authors discuss implications for disease modification and the ultimate goal of prevention. The authors reviewed literature from PubMed, EMBASE, and Web of Science.

EXPERT OPINION

CD serves as a unique opportunity to explore the role of the intestinal microbiota on the development of chronic autoimmune disease. While research to date provides a solid foundation, most studies have been case-control and thus do not have capacity to explore the mechanistic role of the microbiota in CD onset. Further longitudinal studies and integrated multi-omics are necessary for investigating CD pathogenesis.

Role of the gut microbiota in the pathogenesis of coeliac disease and potential therapeutic implications

PURPOSE

Although genetic predisposition and exposure to dietary gluten are considered necessary triggers for the development of coeliac disease, alterations in the gut microbial composition may also contribute towards the pathogenesis of coeliac disease. This review aims to provide an overview of the available data on the potential mechanisms through which the gut microbiota plays a role in the causation of coeliac disease and to discuss the potential therapeutic strategies that could diminish the consequences of microbial dysbiosis.

METHOD

A search of the literature was performed using the PubMed, Embase, and JSTOR databases; relevant articles were included.

RESULTS

Recent studies in patients with coeliac disease have reported an increase in the relative amounts of gram negative bacterial genera such as Bacteroides, Prevotella, and Escherichia, and reduced amounts of protective anti-inflammatory bacteria such as Bifidobacteria and Lactobacilli. Dysbiotic microbiota may lead to a dysregulated immune response that may contribute to the pathogenesis of coeliac disease. In infancy, antibiotic use and certain infant feeding practices may lead to alterations in the developing gut microbiota to influence the immune maturation process and predispose to coeliac disease.

CONCLUSION

The induction of the intestinal immune system and gluten intolerance may be influenced by the relative abundance of certain microbiota. Factors such as infant feeding practices, diet, antibiotics, and infections, may be involved in the development of coeliac disease due to their influence on gut microbial composition. The efficacy of potential modulators of the gut microbiota such as probiotics, prebiotics, and fecal microbial transplant as adjunctive treatments to gluten-free diet in coeliac disease is unproven and requires further investigation.

Novel Therapeutic Strategies for Celiac Disease

Celiac disease (CeD) is a widespread autoimmune enteropathy caused by dietary gluten peptides in genetically susceptible individuals, which includes a range of intestinal and extraintestinal manifestations. Currently, there is no effective treatment for CeD other than strict adherence to a gluten-free diet (GFD). However, persistent or frequent symptoms and also partial villus atrophy were observed in some patients with CeD due to intentional or inadvertent gluten exposure during the use of GFD. It means that GFD alone is not enough to control CeD symptoms and long-term complications. Accordingly, new therapeutic approaches for CeD treatment such as gluten proteolysis, removing gluten from the digestive tract, promoting tight junction assembly, inhibiting intestinal tissue transglutaminase 2, using probiotics, and developing immunotherapeutic methods have been proposed through different strategies. This review focused on discussing the novel therapeutic strategies for CeD management.

Celiac Disease and Non-celiac Wheat Sensitivity: State of Art of Non-dietary Therapies

Gluten related disorders (GRD), which include celiac disease, non-celiac wheat sensitivity and wheat allergy are heterogeneous conditions triggered by ingestion of gluten-containing grains. Together, their prevalence is estimated to be ~5% in the general population, however, in the last years the number of diagnoses has been rapidly increasing. To this day, the gold standard treatment for these disorders is the complete removal of gluten-containing grains from the diet. Although this therapy results effective in the majority of patients, up to 30% of individuals affected by GRD continue to present persistent symptoms. In addition, gluten-free diet has been shown to have poor nutritional quality and to cause a socio-economic burden in patients' quality of life. In order to respond to these issues, the scientific community has been focusing on finding additional and adjuvant non-dietary therapies. In this review, we focus on two main gluten related disorders, celiac disease and non-celiac wheat sensitivity. We delineate the actual knowledge about potential treatments and their relative efficacy in pre-clinical and clinical trials.

Probiotics, Prebiotics and Other Dietary Supplements for Gut Microbiota Modulation in Celiac Disease Patients

To date, the only available treatment for celiac disease (CD) patients is a life-lasting gluten-free diet (GFD). Lack of adherence to the GFD leads to a significant risk of adverse health consequences. Food cross-contamination, nutritional imbalances, and persistent gastrointestinal symptoms are the main concerns related to GFD. Moreover, despite rigid compliance to GFD, patients struggle in achieving a full restoring of the gut microbiota, which plays a role in the nutritive compounds processing, and absorption. Pivotal studies on the supplementation of GFD with probiotics, such as Bifidobacterium and Lactobacilli, reported a potential to restore gut microbiota composition and to pre-digest gluten in the intestinal lumen, reducing the inflammation associated with gluten intake, the intestinal permeability, and the cytokine and antibody production. These findings could explain an improvement in symptoms and quality of life in patients treated with GFD and probiotics. On the other hand, the inclusion of prebiotics in GFD could also be easy to administer and cost-effective as an adjunctive treatment for CD, having the power to stimulate the growth of potentially health-promoting bacteria strains. However, evidence regarding the use of prebiotics and probiotics in patients with CD is still insufficient to justify their use in clinical practice.

Celiac disease and reproductive failures: An update on pathogenic mechanisms

Celiac disease (CD) is an autoimmune disorder that occurs in genetically predisposed people in which the ingestion of gluten leads to damage in the small intestine that clinically presents with malabsorption-related symptoms. CD can also be the underlying cause of several non-gastrointestinal symptoms. This review summarizes evidence on the relationship between CD and gynecological/obstetric disorders like reproductive failures. Although much has been reported on such a linkage, the pathogenic mechanisms remain unclear, especially those underlying extra-gastrointestinal clinical manifestations. Studies conducted on celiac subjects presenting gynecological/obstetric disorders have pointed to intestinal malabsorption, coagulation alterations, immune-mediated tissue damage, and endometrial inflammation as the main responsible pathogenic mechanisms. Currently, however, the knowledge of such mechanisms is insufficient, and further studies are needed to gain a more thorough understanding of the matter.

Can a Synbiotic Supplementation Contribute to Decreasing Anti-Tissue Transglutaminase Levels in Children with Potential Celiac Disease?

PURPOSE

Synbiotics can alleviate some intestinal pathologies or prevent trigger mechanisms for some diseases such as celiac disease (CD). If patients with high levels of anti-tissue transglutaminase (anti-tTG) immunoglobulin A (IgA) antibodies have normal duodenal histology, they are followed as potential CD patients. The aim of this study was to investigate the effect of synbiotic use on the blood levels of anti-tTG antibodies in children.

METHODS

Eighty-two patients with high anti-tTG levels were included in this study. Patients were randomly divided into two groups. The synbiotic group was treated with a daily dose of a synbiotic including multi-strain probiotics for 20 days. The control group was not administered any medication. Anti-tTG values at baseline and repeat measurements and the percentage change in anti-tTG levels between groups were compared.

RESULTS

The anti-tTG level at baseline was 36 U/mL (interquartile range [IQR], 26.4-68 U/mL) in the synbiotic group, and it decreased significantly to 13 U/mL (IQR, 6.5-27.5 U/mL) after 20 days (p<0.05). The anti-tTG level at baseline was 46 U/mL (IQR, 31-89 U/mL) in the control group, which also decreased significantly to 23 U/mL (IQR, 7-41 U/mL) after 20 days (p<0.05). Anti-tTG levels exhibited 73% and 56% decreases in the synbiotic and control groups, respectively (p<0.05).

CONCLUSION

It may be speculated that a synbiotic supplementation can contribute to decreasing anti-tTG levels in children with potential CD.

Gut Microbiota in Celiac Disease: Is There Any Role for Probiotics?

Celiac disease (CD) is an immune-mediated disorder initiated by the ingestion of gluten in genetically predisposed individuals. Recent data shows that changes in the gut microbiome composition and function are linked with chronic inflammatory diseases; this might also be the case for CD. The main aim of this manuscript is to discuss our present knowledge of the relationships between gut microbiota alterations and CD and to understand if there is any role for probiotics in CD therapy. PubMed was used to search for all of the studies published from November 2009 to November 2019 using key words such as “Celiac Disease” and “Microbiota” (306 articles), “Celiac Disease” and “Gastrointestinal Microbiome” (139), and “Probiotics” and “Celiac Disease” (97 articles). The search was limited to articles published in English that provided evidence-based data. Literature analysis showed that the gut microbiota has a well-established role in gluten metabolism, in modulating the immune response and in regulating the permeability of the intestinal barrier. Promising studies suggest a possible role of probiotics in treating and/or preventing CD. Nevertheless, human trials on the subject are still scarce and lack homogeneity. A possible role was documented for probiotics in improving CD-related symptoms, modulating the peripheral immune response and altering the fecal microbiota, although the results were not consistent in all of the studies. No evidence was found that probiotic administration might prevent CD onset. Knowledge of the role of intestinal bacteria in the development of CD opens new possibilities for its treatment through probiotic administration, even though further studies are needed to better clarify whether probiotics can help treat or prevent the disease and to define which probiotics to use, at what dose and for how long.

Insights into the reason of Human-Residential Bifidobacteria (HRB) being the natural inhabitants of the human gut and their potential health-promoting benefits

Members of Bifidobacterium are among the first microbes to colonise the human gut, and certain species are recognised as the natural resident of human gut microbiota. Their presence in the human gut has been associated with health-promoting benefits and reduced abundance of this genus is linked with several diseases. Bifidobacterial species are assumed to have coevolved with their hosts and include members that are naturally present in the human gut, thus recognised as Human-Residential Bifidobacteria (HRB). The physiological functions of these bacteria and the reasons why they occur in and how they adapt to the human gut are of immense significance. In this review, we provide an overview of the biology of bifidobacteria as members of the human gut microbiota and address factors that contribute to the preponderance of HRB in the human gut. We highlight some of the important genetic attributes and core physiological traits of these bacteria that may explain their adaptive advantages, ecological fitness, and competitiveness in the human gut. This review will help to widen our understanding of one of the most important human commensal bacteria and shed light on the practical consideration for selecting bifidobacterial strains as human probiotics.

Advances in understanding the potential therapeutic applications of gut microbiota and probiotic mediated therapies in celiac disease

INTRODUCTION

Celiac Disease (CD) is an autoimmune enteropathy caused by exposure to gluten in genetically predisposed people. While gluten is the main driving force in CD, evidence has shown that microbiota might be involved in the pathogenesis, development, and clinical presentation of CD. Microbiota manipulation may modify its functional capacity and may be crucial for setting-up potential preventive or therapeutic application. Moreover, probiotics are an excellent source of endopeptidases for digesting gluten.

AREAS COVERED

In this narrative review we illustrate all the recent scientific discoveries in this field including CD pathogenetic mechanism where gut microbiota might be involved and possible use of probiotics in CD prevention and treatment.

EXPERT OPINION

In the future, probiotics could be used as an add-on medication for strengthening/facilitating the gluten-free diet (GFD) and improving symptoms; the prospect of using it for therapeutic purposes is to be sought in a more distant future.

A Probiotic Preparation Hydrolyzes Gliadin and Protects Intestinal Cells from the Toxicity of Pro-Inflammatory Peptides

Celiac disease (CD) is an autoimmune enteropathy caused by an intolerance to gluten proteins. It has been hypothesized that probiotic bacteria may exert beneficial effects by modulating inflammatory processes and by sustaining peptide hydrolysis at the intestinal level. This study aims at evaluating the capacity of a probiotic mixture (two different strains of lactobacilli and three of bifidobacteria) to hydrolyze gluten peptides following simulated gastrointestinal digestion of gliadin (PT-gliadin). The capacity of bacterial hydrolysates to counteract the toxic effects of gliadin-derived peptides in Caco-2 cells was also assessed. The protein and peptide mixtures, untreated or proteolyzed with the probiotic preparation, were analyzed before and after each proteolytic step with different techniques (SDS-PAGE, reverse phase HPLC, filtration on different molecular cut-off membranes). These experiments demonstrated that PT-gliadin can be further digested by bacteria into lower molecular weight peptides. PT-gliadin, untreated or digested with the probiotics, was then used to evaluate oxidative stress, IL-6 cytokine production and expression of tight junctions’ proteins—such as occludin and zonulin—in Caco-2 cells. PT-gliadin induced IL-6 production and modulation and redistribution of zonulin and occludin, while digestion with the probiotic strains reversed these effects. Our data indicate that this probiotic mixture may exert a protective role in CD.

Pathogenesis of Celiac Disease and Other Gluten Related Disorders in Wheat and Strategies for Mitigating Them

Wheat is a major cereal crop providing energy and nutrients to the billions of people around the world. Gluten is a structural protein in wheat, that is necessary for its dough making properties, but it is responsible for imparting certain intolerances among some individuals, which are part of this review. Most important among these intolerances is celiac disease, that is gluten triggered T-cell mediated autoimmune enteropathy and results in villous atrophy, inflammation and damage to intestinal lining in genetically liable individuals containing human leukocyte antigen DQ2/DQ8 molecules on antigen presenting cells. Celiac disease occurs due to presence of celiac disease eliciting epitopes in gluten, particularly highly immunogenic alpha-gliadins. Another gluten related disorder is non-celiac gluten-sensitivity in which innate immune-response occurs in patients along with gastrointestinal and non-gastrointestinal symptoms, that disappear upon removal of gluten from the diet. In wheat allergy, either IgE or non-IgE mediated immune response occurs in individuals after inhalation or ingestion of wheat. Following a life-long gluten-free diet by celiac disease and non-celiac gluten-sensitivity patients is very challenging as none of wheat cultivar or related species stands safe for consumption. Hence, different molecular biology, genetic engineering, breeding, microbial, enzymatic, and chemical strategies have been worked upon to reduce the celiac disease epitopes and the gluten content in wheat. Currently, only 8.4% of total population is affected by wheat-related issues, while rest of population remains safe and should not remove wheat from the diet, based on false media coverage.

Dietary Approaches to the Management of Autism Spectrum Disorders

This chapter reviews the literature surrounding autism spectrum disorders (ASD) and their relation to gastrointestinal (GI), behavioral, neurological, and immunological functioning. Individuals with ASD often have poor GI health, including bowel motility issues, autoimmune and/or other adverse responses to certain foods, and lack of necessary nutrient absorption. These issues may be caused or exacerbated by restrictive behavioral patterns (e.g., preference for sweet and salty foods and/or refusal of healthy foods). Those individuals with GI issues tend to demonstrate more behavioral deficits (e.g., irritability, agitation, hyperactivity) and also tend to have an imbalance in overall gut microbiome composition, thus corroborating several studies that have implicated brain-gut pathways as potential mediators of behavioral dysfunction.We examine the literature regarding dietary approaches to managing ASDs, including elimination diets for gluten, casein, or complex carbohydrates, a ketogenic diet, and a low oxalate diet. We also explore the research examining dietary supplements such as fatty acids, pro- and prebiotics, vitamins, minerals, glutathione, phytochemicals, and hormones. The research on dietary approaches to managing ASDs is limited and the results are mixed. However, a few approaches, such as the gluten-free/casein-free diet, fatty acid supplementation, and pre/probiotics have generally demonstrated improved GI and associated behavioral symptoms. Given that GI issues seem to be overrepresented in ASD populations, and that GI issues have been associated with a number behavioral and neurological deficits, dietary manipulation may offer a cheap and easily implemented approach to improve the lives of those with ASD.

Celiac Disease and the Microbiome

Growing evidence supports the hypothesis that changes in both the composition and function of the intestinal microbiome are associated with a number of chronic inflammatory diseases including celiac disease (CD). One of the major advances in the field of microbiome studies over the last few decades has been the development of culture-independent approaches to identify and quantify the components of the human microbiota. The study of nucleic acids DNA and RNA found in feces or other biological samples bypasses the need for tissue cultures and also allows the characterization of non-cultivable microbes. Current evidence on the composition of the intestinal microbiome and its role as a causative trigger for CD is highly heterogeneous and sometimes contradictory. This review is aimed at summarizing both pre-clinical (basic science data) and clinical (cross-sectional and prospective studies) evidence addressing the relationship between the intestinal microbiome and CD.

The Gut Microbiota in Celiac Disease and probiotics

Celiac disease (CeD) is an immune-mediated enteropathy, and unique in that the specific trigger is known: gluten. The current mainstay of therapy is a gluten-free diet (GFD). As novel therapies are being developed, complementary strategies are also being studied, such as modulation of the gut microbiome. The gut microbiota is involved in the initiation and perpetuation of intestinal inflammation in several chronic diseases. Intestinal dysbiosis has been reported in CeD patients, untreated or treated with GFD, compared to healthy subjects. Several studies have identified differential bacterial populations associated with CeD patients and healthy subjects. However, it is still not clear if intestinal dysbiosis is the cause or effect of CeD. Probiotics have also been considered as a strategy to modulate the gut microbiome to an anti-inflammatory state. However, there is a paucity of data to support their use in treating CeD. Further studies are needed with therapeutic microbial formulations combined with human trials on the use of probiotics to treat CeD by restoring the gut microbiome to an anti-inflammatory state.