Microbial Transglutaminase Is Immunogenic and Potentially Pathogenic in Pediatric Celiac Disease

The Frequently Used Industrial Food Process Additive, Microbial Transglutaminase: Boon or Bane

Microbial transglutaminase (mTG) is a frequently consumed processed food additive, and use of its cross-linked complexes is expanding rapidly. It was designated as a processing aid and was granted the generally recognized as safe (GRAS) classification decades ago, thus avoiding thorough assessment according to current criteria of toxicity and public health safety. In contrast to the manufacturer's declarations and claims, mTG and/or its transamidated complexes are proinflammatory, immunogenic, allergenic, pathogenic, and potentially toxic, hence raising concerns for public health. Being a member of the transglutaminase family and functionally imitating the tissue transglutaminase, mTG was recently identified as a potential inducer of celiac disease. Microbial transglutaminase and its docked complexes have numerous detrimental effects. Those harmful aspects are denied by the manufacturers, who claim the enzyme is deactivated when heated or by gastric acidity, and that its covalently linked isopeptide bonds are safe. The present narrative review describes the potential side effects of mTG, highlighting its thermostability and activity over a broad pH range, thus, challenging the manufacturers' and distributers' safety claims. The national food regulatory authorities and the scientific community are urged to reevaluate mTG's GRAS status, prioritizing public health protection against the possible risks associated with this enzyme and its health-damaging consequences.

The Potential Harmful Effects of Genetically Engineered Microorganisms (GEMs) on the Intestinal Microbiome and Public Health

Gut luminal dysbiosis and pathobiosis result in compositional and biodiversified alterations in the microbial and host co-metabolites. The primary mechanism of bacterial evolution is horizontal gene transfer (HGT), and the acquisition of new traits can be achieved through the exchange of mobile genetic elements (MGEs). Introducing genetically engineered microbes (GEMs) might break the harmonized balance in the intestinal compartment. The present objectives are: 1. To reveal the role played by the GEMs' horizontal gene transfers in changing the landscape of the enteric microbiome eubiosis 2. To expand on the potential detrimental effects of those changes on the human genome and health. A search of articles published in PubMed/MEDLINE, EMBASE, and Scielo from 2000 to August 2023 using appropriate MeSH entry terms was performed. The GEMs' horizontal gene exchanges might induce multiple human diseases. The new GEMs can change the long-term natural evolution of the enteric pro- or eukaryotic cell inhabitants. The worldwide regulatory authority's safety control of GEMs is not enough to protect public health. Viability, biocontainment, and many other aspects are only partially controlled and harmful consequences for public health should be avoided. It is important to remember that prevention is the most cost-effective strategy and primum non nocere should be the focus.

Safety evaluation of the food enzyme protein-glutamine γ-glutamyltransferase from the non-genetically modified Streptomyces mobaraensis strain M2020197

The food enzyme protein-glutamine γ-glutamyltransferase (protein-glutamine: amine γ-glutamyltransferase; EC 2.3.2.13) is produced with the non-genetically modified Streptomyces mobaraensis strain M2020197 by Taixing Dongsheng Bio-Tech Co. Ltd. The identity of the production strain and the absence of viable cells could not be established. The food enzyme is intended to be used in eight food manufacturing processes: processing of cereals and other grains for the production of (1) baked products, (2) cereal-based products other than baked; processing of dairy products for the production of (3) fermented dairy products, (4) cheese, (5) dairy desserts; processing of plant- and fungal-derived products for the production of (6) meat analogues, (7) plant-based analogues of milk and milk products; processing of meat and fish products for the production of (8) modified meat and fish products. Dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to 3.498 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 91 mg TOS/kg bw per day. The calculated margin of exposure for each age group was 36 (infants), 26 (toddlers), 50 (children), 99 (adolescents), 115 (adults) and 133 (the elderly). A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that a risk of allergic reactions upon dietary exposure to this food enzyme cannot be excluded, but the likelihood is low. The safety of the food enzyme could not be established given the derived margins of exposure. Therefore, the Panel concluded that the food enzyme could not be considered safe under the intended conditions of use.

Cross-reactivity and sequence similarity between microbial transglutaminase and human tissue antigens

Microbial transglutaminase (mTG) is a bacterial survival factor, frequently used as a food additive to glue processed nutrients. As a result, new immunogenic epitopes are generated that might drive autoimmunity. Presently, its contribution to autoimmunity through epitope similarity and cross-reactivity was investigated. Emboss Matcher was used to perform sequence alignment between mTG and various antigens implicated in many autoimmune diseases. Monoclonal and polyclonal antibodies made specifically against mTG were applied to 77 different human tissue antigens using ELISA. Six antigens were detected to share significant homology with mTG immunogenic sequences, representing major targets of common autoimmune conditions. Polyclonal antibody to mTG reacted significantly with 17 out of 77 tissue antigens. This reaction was most pronounced with mitochondrial M2, ANA, and extractable nuclear antigens. The results indicate that sequence similarity and cross-reactivity between mTG and various tissue antigens are possible, supporting the relationship between mTG and the development of autoimmune disorders 150W.

Microbiological transglutaminase: Biotechnological application in the food industry

Microbial transglutaminases (mTGs) belong to the family of global TGs, isolated and characterised by various bacterial strains, with the first being Streptomyces mobaraensis. This literature review also discusses TGs of animal and plant origin. TGs catalyse the formation of an isopeptide bond, cross-linking the amino and acyl groups. Due to its broad enzymatic activity, TG is extensively utilised in the food industry. The annual net growth in the utilisation of enzymes in the food processing industry is estimated to be 21.9%. As of 2020, the global food enzymes market was valued at around $2.3 billion USD (mTG market was estimated to be around $200 million USD). Much of this growth is attributed to the applications of mTG, benefiting both producers and consumers. In the food industry, TG enhances gelation and modifies emulsification, foaming, viscosity, and water-holding capacity. Research on TG, mainly mTG, provides increasing insights into the wide range of applications of this enzyme in various industrial sectors and promotes enzymatic processing. This work presents the characteristics of TGs, their properties, and the rationale for their utilisation. The review aims to provide theoretical foundations that will assist researchers worldwide in building a methodological framework and furthering the advancement of biotechnology research.

pH and Thrombin Concentration Are Decisive in Synthesizing Stiff, Stable, and Open-Porous Fibrin-Collagen Hydrogel Blends without Chemical Cross-Linker

Fibrin-collagen hydrogel blends exhibit high potential for tissue engineering applications. However, it is still unclear whether the underlying cross-linking mechanisms are of chemical or physical nature. It is here hypothesized that chemical cross-linkers play a negligible role and that instead pH and thrombin concentration are decisive for synthetizing blends with high stiffness and hydrolytic stability. Different fibrin-collagen formulations (pure and with additional transglutaminase) are used and the blends' compaction rate, hydrolytic stability, compressive strength, and hydrogel microstructure are investigated. The effect of thrombin concentration on gel compaction is examined and the importance of pH control during synthesis observed. It is revealed that transglutaminase impairs gel stability and it is deduced that fibrin-collagen blends mainly cross-link by mechanical interactions due to physical fibril entanglement as opposed to covalent bonds from chemical cross-linking. High thrombin concentrations and basic pH during synthesis reduce gel compaction and enhance stiffness and long-term stability. Scanning electron microscopy reveals a highly interpenetrating fibrous network with unique, interconnected open-porous microstructures. Endothelial cells proliferate on the blends and form a confluent monolayer. This study reveals the underlying cross-linking mechanisms and presents enhanced fibrin-collagen blends with high stiffness, hydrolytic stability, and large, interconnected pores; findings that offer high potential for advanced tissue engineering applications.

Gluten-free diet exposure prohibits pathobiont expansion and gluten sensitive enteropathy in B cell deficient JH-/- mice

In humans, celiac disease (CeD) is a T-cell-driven gluten-sensitive enteropathy (GSE) localized to the small bowel (duodenum). The presence of antibodies specific for gluten- and self-antigens are commonly used diagnostic biomarkers of CeD and are considered to play a role in GSE pathogenesis. Previously, we have described an apparent T-cell-mediated GSE in CD19-/- mice, which develop weak and abnormal B cell responses. Here, we expand on this observation and use a mouse model of complete B cell deficiency (JH-/- mice), to show that absence of a humoral immune response also promotes development of a GSE. Furthermore, 16S analysis of microbial communities in the small intestine demonstrates that a gluten-free diet suppresses the expansion of anaerobic bacteria in the small intestine and colonization of the small intestine by a specific pathobiont. Finally, we also observe that SI enteropathy in mice fed a gluten-rich diet is positively correlated with the abundance of several microbial peptidase genes, which supports that bacterial metabolism of gluten may be an important driver of GSE in our model. Collectively, results from our experiments indicate that JH-/- mice will be a useful resource to investigators seeking to empirically delineate the contribution of humoral immunity on GSE pathogenesis, and support the hypothesis that humoral immunity promotes tolerance to gluten.

Defective humoral immunity disrupts bile acid homeostasis which promotes inflammatory disease of the small bowel

Mucosal antibodies maintain gut homeostasis by promoting spatial segregation between host tissues and luminal microbes. Whether and how mucosal antibody responses influence gut health through modulation of microbiota composition is unclear. Here, we use a CD19^-/- mouse model of antibody-deficiency to demonstrate that a relationship exists between dysbiosis, defects in bile acid homeostasis, and gluten-sensitive enteropathy of the small intestine. The gluten-sensitive small intestine enteropathy that develops in CD19^-/- mice is associated with alterations to luminal bile acid composition in the SI, marked by significant reductions in the abundance of conjugated bile acids. Manipulation of bile acid availability, adoptive transfer of functional B cells, and ablation of bacterial bile salt hydrolase activity all influence the severity of small intestine enteropathy in CD19^-/- mice. Collectively, results from our experiments support a model whereby mucosal humoral immune responses limit inflammatory disease of the small bowel by regulating bacterial BA metabolism.

Microbial Transglutaminase Is a Very Frequently Used Food Additive and Is a Potential Inducer of Autoimmune/Neurodegenerative Diseases

Microbial transglutaminase (mTG) is a heavily used food additive and its industrial transamidated complexes usage is rising rapidly. It was classified as a processing aid and was granted the GRAS (generally recognized as safe) definition, thus escaping full and thorough toxic and safety evaluations. Despite the manufacturers claims, mTG or its cross-linked compounds are immunogenic, pathogenic, proinflammatory, allergenic and toxic, and pose a risk to public health. The enzyme is a member of the transglutaminase family and imitates the posttranslational modification of gluten, by the tissue transglutaminase, which is the autoantigen of celiac disease. The deamidated and transamidated gliadin peptides lose their tolerance and induce the gluten enteropathy. Microbial transglutaminase and its complexes increase intestinal permeability, suppresses enteric protective pathways, enhances microbial growth and gliadin peptide's epithelial uptake and can transcytose intra-enterocytically to face the sub-epithelial immune cells. The present review updates on the potentially detrimental side effects of mTG, aiming to interest the scientific community, induce food regulatory authorities' debates on its safety, and protect the public from the mTG unwanted effects.

Toward Intracellular Bioconjugation Using Transition-Metal-Free Techniques

Bioconjugation is the chemical strategy of covalent modification of biomolecules, using either an external reagent or other biomolecules. Since its inception in the twentieth century, the technique has grown by leaps and bounds, and has a variety of applications in chemical biology. However, it is yet to reach its full potential in the study of biochemical processes in live cells, mainly because the bioconjugation strategies conflict with cellular processes. This has mostly been overcome by using transition metal catalysts, but the presence of metal centers limit them to in vitro use, or to the cell surface. These hurdles can potentially be circumvented by using metal-free strategies. However, the very modifications that are necessary to make such metal-free reactions proceed effectively may impact their biocompatibility. This is because biological processes are easily perturbed and greatly depend on the prevailing inter- and intracellular environment. With this taken into consideration, this review analyzes the applicability of the transition-metal-free strategies reported in this decade to the study of biochemical processes in vivo.

Alpha-enolase involvement in intestinal and extraintestinal manifestations of celiac disease

Celiac disease is a life-long intestinal autoimmune disease, characterized by the gluten intolerance and chronic enteric inflammation. Traditionally presented by intestinal manifestations, however, a shift toward extra intestinal presentation is taking place. One of the affected organs is the nervous systems presented by neuropsychiatric manifestations, hence the mechanism and pathways are not clear. The presence of neuronal and alpha-enolases and their corresponding antibodies were noticed in the mucosa and serum of celiac disease patients, as well as in other various autoimmune diseases with psycho-neurological manifestations. The aims of the present review are to screen the literature on different isoforms of enolase, mainly alpha enolase, and their specific antibodies and to suggest their potential pathophysiological mechanisms relaying the enolases to intestinal or extraintestinal celiac disease manifestations. The shared aspects between the enolases and celiac disease and the cross-talks between alpha-enolase and tissue transglutaminase suggest new potential pathophysiological mechanisms that might drive celiac disease evolvement.

Gut microbiome investigation in celiac disease: from methods to its pathogenetic role

Our body is inhabited by a variety of microbes (microbiota), mainly bacteria, that outnumber our own cells. Until recently, most of what we knew about the human microbiota was based on culture methods, whereas a large part of the microbiota is uncultivable, and consequently previous information was limited. The advent of culture-independent methods and, particularly, of next-generation sequencing (NGS) methodology, marked a turning point in studies of the microbiota in terms of its composition and of the genes encoded by these microbes (microbiome). The microbiome is influenced predominantly by environmental factors that cause a large inter-individual variability (~20%) being its heritability only 1.9%. The gut microbiome plays a relevant role in human physiology, and its alteration ("dysbiosis") has been linked to a variety of inflammatory gut diseases, including celiac disease (CD). CD is a chronic, immune-mediated disorder that is triggered by both genetic (mainly HLA-DQ2/DQ8 haplotypes) and environmental factors (gluten), but, in recent years, a large body of experimental evidence suggested that the gut microbiome is an additional contributing factor to the pathogenesis of CD. In this review, we summarize the literature that has investigated the gut microbiome associated with CD, the methods and biological samples usually employed in CD microbiome investigations and the putative pathogenetic role of specific microbial alterations in CD. In conclusion, both gluten-microbe and host-microbe interactions drive the gluten-mediated immune response. However, it remains to be established whether the CD-associated dysbiosis is the consequence of the disease, a simple concomitant association or a concurring causative factor.

"Let Food Be Thy Medicine": Gluten and Potential Role in Neurodegeneration

Wheat is a most favored staple food worldwide and its major protein is gluten. It is involved in several gluten dependent diseases and lately was suggested to play a role in non-celiac autoimmune diseases. Its involvement in neurodegenerative conditions was recently suggested but no cause-and-effect relationship were established. The present narrative review expands on various aspects of the gluten-gut-brain axes events, mechanisms and pathways that connect wheat and gluten consumption to neurodegenerative disease. Gluten induced dysbiosis, increased intestinal permeabillity, enteric and systemic side effects, cross-reactive antibodies, and the sequence of homologies between brain antigens and gluten are highlighted. This combination may suggest molecular mimicry, alluding to some autoimmune aspects between gluten and neurodegenerative disease. The proverb of Hippocrates coined in 400 BC, "let food be thy medicine," is critically discussed in the frame of gluten and potential neurodegeneration evolvement.

The Possible Role of Pathogenic and Non-Pathogenic Bacteria in Initiation and Exacerbation of Celiac Disease; A Comprehensive Review

Celiac Disease (CD) is an immune-mediated enteropathy, generally of the proximal intestine, that occurs in genetically susceptible individuals triggered by the ingestion of gluten. The incidence and frequency of CD are increasing, and it is predicted that CD affects approximately 1% of the people worldwide. The common clinical manifestations of CD are divided in two sections, including classic and non-classic symptoms that can be created in childhood and adulthood. The relationship between pathogenic and non-pathogenic bacteria with CD is complex and multidirectional. In previous published studies, results demonstrated the triggering impact of bacteria, viruses, and parasites on initiation and development of Inflammatory Bowel Disease (IBD) and Irritable Bowel Syndrome (IBS). Different studies revealed the inducing effect of pathogenic and non-pathogenic bacteria on CD. However, increasing evidence proposes that some of these microorganisms can also play several positive roles in CD process. Although information of the pathogenesis of the CD is quickly expanding, the possible role of bacteria needs further examination. In conclusion, with respect to the possible correlation between different bacteria in CD, the current review-based study aims to discuss the possible relationship between CD and pathogenic and non-pathogenic bacteria and to show various and significant aspects of mechanisms involved in the CD process.

Enzyme-catalysed polymer cross-linking: Biocatalytic tools for chemical biology, materials science and beyond

Intermolecular cross-linking is one of the most important techniques that can be used to fundamentally alter the material properties of a polymer. The introduction of covalent bonds between individual polymer chains creates 3D macromolecular assemblies with enhanced mechanical properties and greater chemical or thermal tolerances. In contrast to many chemical cross-linking reactions, which are the basis of thermoset plastics, enzyme catalysed processes offer a complimentary paradigm for the assembly of cross-linked polymer networks through their predictability and high levels of control. Additionally, enzyme catalysed reactions offer an inherently 'greener' and more biocompatible approach to covalent bond formation, which could include the use of aqueous solvents, ambient temperatures, and heavy metal-free reagents. Here, we review recent progress in the development of biocatalytic methods for polymer cross-linking, with a specific focus on the most promising candidate enzyme classes and their underlying catalytic mechanisms. We also provide exemplars of the use of enzyme catalysed cross-linking reactions in industrially relevant applications, noting the limitations of these approaches and outlining strategies to mitigate reported deficiencies.

Postbiotic-Enabled Targeting of the Host-Microbiota-Pathogen Interface: Hints of Antibiotic Decline?

Mismanagement of bacterial infection therapies has undermined the reliability and efficacy of antibiotic treatments, producing a profound crisis of the antibiotic drug market. It is by now clear that tackling deadly infections demands novel strategies not only based on the mere toxicity of anti-infective compounds. Host-directed therapies have been the first example as novel treatments with alternate success. Nevertheless, recent advances in the human microbiome research have provided evidence that compounds produced by the microbial metabolism, namely postbiotics, can have significant impact on human health. Such compounds target the host-microbe-pathogen interface rescuing biotic and immune unbalances as well as inflammation, thus providing novel therapeutic opportunities. This work discusses critically, through literature review and personal contributions, these novel nonantibiotic treatment strategies for infectious disease management and resistance prevention, which could represent a paradigm change rocking the foundation of current antibiotic therapy tenets.

A recent update on the use of microbial transglutaminase for the generation of biotherapeutics

The recent scientific progresses on the use of enzyme-mediated reactions in organic, non-aqueous and aqueous media have significantly supported the growing demand of new biotechnological and/or pharmacological products. Today, a plethora of microbial enzymes, used as biocatalysts, are available. Among these, microbial transglutaminases (MTGs) are broadly used for their ability to catalyse the formation of an isopeptide bond between the γ-amide group of glutamines and the ε-amino group of lysine. Due to their promiscuity towards primary amine-containing substrates and the more stringent specificity for glutamine-containing peptide sequences, several combined approaches can be tailored for different settings, making MTGs very attractive catalysts for generating protein-protein and protein small molecule's conjugates. The present review offers a recent update on the modifications attainable by MTG-catalysed bioreactions as reported between 2014 and 2019. In particular, we present a detailed and comparative overview on the MTG-based methods for proteins and antibodies engineering, with a particular outlook on the synthesis of homogeneous antibody-drug conjugates.

Antibodies against neo-epitope of microbial and human transglutaminase complexes as biomarkers of childhood celiac disease

Tissue transglutaminase (tTG) and microbial transglutaminase (mTG) cross-link gliadins to form complexes that expose immunogenic neo-epitopes to produce tTG and mTG-neo-epitope antibodies. The aim of this study was to test the diagnostic performance of antibodies against non-complexed and complexed forms of transglutaminases, to correlate their activities to the intestinal damage and to explore age group dependency in celiac disease (CD). A total of 296 children with untreated CD and 215 non-celiac disease controls were checked by in-house enzyme-linked immunosorbent assays detecting immunoglobulin (Ig)A, IgG or combined detection of IgA and IgG (check) against tTG, AESKULISA® tTG New Generation (tTG-neo) and mTG-neo (RUO), IgA and IgG antibodies against deamidated gliadin peptide (DGP) and human IgA anti-endomysium antibodies (EMA) using AESKUSLIDES® EMA. Intestinal pathology was graded according the revised Marsh criteria, and age dependencies of the antibody activities were analysed. Using cut-offs estimated from receiver operating characteristic (ROC) curves, the highest area under curve (AUC) of the TG assays was 0·963 for tTG-neo check, followed by tTG check (0·962) when the diagnosis was based on enteric mucosal histology. tTG-neo check was the most effective to reflect the intestinal abnormalities in CD (r = 0·795, P < 0·0001). High levels of anti-mTG-neo IgG and anti-tTG-neo IgG appeared in the earlier age groups, as compared to anti-tTG IgG (P < 0·001). Considering antibody diagnostic performance based on AUC, enteric damage reflection and predictability at an early age, the anti-neo tTG check was the most effective diagnostic biomarker for pediatric CD. The mTG neo check might represent a new marker for CD screening, diagnosis and predictability.

Processed Food Additive Microbial Transglutaminase and Its Cross-Linked Gliadin Complexes Are Potential Public Health Concerns in Celiac Disease

Microbial transglutaminase (mTG) is a survival factor for microbes, but yeasts, fungi, and plants also produce transglutaminase. mTG is a cross-linker that is heavily consumed as a protein glue in multiple processed food industries. According to the manufacturers' claims, microbial transglutaminase and its cross-linked products are safe, i.e., nonallergenic, nonimmunogenic, and nonpathogenic. The regulatory authorities declare it as "generally recognized as safe" for public users. However, scientific observations are accumulating concerning its undesirable effects on human health. Functionally, mTG imitates its family member, tissue transglutaminase, which is the autoantigen of celiac disease. Both these transglutaminases mediate cross-linked complexes, which are immunogenic in celiac patients. The enzyme enhances intestinal permeability, suppresses mechanical (mucus) and immunological (anti phagocytic) enteric protective barriers, stimulates luminal bacterial growth, and augments the uptake of gliadin peptide. mTG and gliadin molecules are cotranscytosed through the enterocytes and deposited subepithelially. Moreover, mucosal dendritic cell surface transglutaminase induces gliadin endocytosis, and the enzyme-treated wheat products are immunoreactive in CD patients. The present review summarizes and updates the potentially detrimental effects of mTG, aiming to stimulate scientific and regulatory debates on its safety, to protect the public from the enzyme's unwanted effects.

Interaction between food antigens and the immune system: Association with autoimmune disorders

It has been shown that environmental factors such as infections, chemicals, and diet play a major role in autoimmune diseases; however, relatively little attention has been given to food components as the most prevalent modifiers of these afflictions. This review summarizes the current body of knowledge related to different mechanisms and associations between food proteins/peptides and autoimmune disorders. The primary factor controlling food-related immune reactions is the oral tolerance mechanism. The failure of oral tolerance triggers immune reactivity against dietary antigens, which may initiate or exacerbate autoimmune disease when the food antigen shares homology with human tissue antigens. Because the conformational fit between food antigens and a host's self-determinants has been determined for only a few food proteins, we examined evidence related to the reaction of affinity-purified disease-specific antibody with different food antigens. We also studied the reaction of monoclonal or polyclonal tissue-specific antibodies with various food antigens and the reaction of food-specific antibodies with human tissue antigens. Examining the assembled information, we postulated that chemical modification of food proteins by different toxicants in food may result in immune reaction against modified food proteins that cross-react with tissue antigens, resulting in autoimmune reactivity. Because we are what our microbiome eats, food can change the gut commensals, and toxins can breach the gut barrier, penetrating into different organs where they can initiate autoimmune response. Conversely, there are also foods and supplements that help maintain oral tolerance and microbiome homeostasis. Understanding the potential link between specific food consumption and autoimmunity in humans may lay the foundation for further research about the proper diet in the prevention of autoimmune diseases.

Microbial transglutaminase should be considered as an environmental inducer of celiac disease

Due to the recent interest in food additives that can act as triggering factors in autoimmune diseases including celiac disease (CD), the present letter to the editor expands on the microbial transglutaminase (mTG). It is heavily consumed by a plethora of food processing industries as "glue of proteins" thus improving product's stability, texture and shelf life. However, more and more information is accumulated lately, questioning its safety. Its cross-linked gliadin complexes are immunogenic in CD. The enzyme increases gliadin uptake, is transported in a trans-epithelial way and deposited below the enterocyte's line, has anti- phagocytic activity, enhances intestinal permeability and creates luminal resistant isopeptide bonds. No doubt that mTG is beneficial to food industries but a caveat to public health is highly recommended.

Gut Antibody Deficiency in a Mouse Model of CVID Results in Spontaneous Development of a Gluten-Sensitive Enteropathy

Primary immunodeficiencies are heritable disorders of immune function. CD19 is a B cell co-receptor important for B cell development, and CD19 deficiency is a known genetic risk factor for a rare form of primary immunodeficiency known as “common variable immunodeficiency” (CVID); an antibody deficiency resulting in low levels of serum IgG and IgA. Enteropathies are commonly observed in CVID patients but the underlying reason for this is undefined. Here, we utilize CD19^−/− mice as a model of CVID to test the hypothesis that antibody deficiency negatively impacts gut physiology under steady-state conditions. As anticipated, immune phenotyping experiments demonstrate that CD19^−/− mice develop a severe B cell deficiency in gut-associated lymphoid tissues that result in significant reductions to antibody concentrations in the gut lumen. Antibody deficiency was associated with defective anti-commensal IgA responses and the outgrowth of anaerobic bacteria in the gut. Expansion of anaerobic bacteria coincides with the development of a chronic inflammatory condition in the gut of CD19^−/− mice that results in an intestinal malabsorption characterized by defects in lipid metabolism and transport. Administration of the antibiotic metronidazole to target anaerobic members of the microbiota rescues mice from disease indicating that intestinal malabsorption is a microbiota-dependent phenomenon. Finally, intestinal malabsorption in CD19^−/− mice is a gluten-sensitive enteropathy as exposure to a gluten-free diet also significantly reduces disease severity in CD19^−/− mice. Collectively, these results support an effect of antibody deficiency on steady-state gut physiology that compliment emerging data from human studies linking IgA deficiency with non-infectious complications associated with CVID. They also demonstrate that CD19^−/− mice are a useful model for studying the role of B cell deficiency and gut dysbiosis on gluten-sensitive enteropathies; a rapidly emerging group of diseases in humans with an unknown etiology.

The Revival of the Battle between David and Goliath in the Enteric Viruses and Microbiota Struggle: Potential Implication for Celiac Disease

The human gut is inhabited by overcrowded prokaryotic communities, a major component of which is the virome, comprised of viruses, bacteriophages, archaea, eukaryotes and bacteria. The virome is required for luminal homeostasis and, by their lytic or synergic capacities, they can regulate the microbial community structure and activity. Dysbiosis is associated with numerous chronic human diseases. Since the virome can impact microbial genetics and behavior, understanding its biology, composition, cellular cycle, regulation, mode of action and potential beneficial or hostile activities can change the present paradigm of the cross-talks in the luminal gut compartment. Celiac disease is a frequent autoimmune disease in which viruses can play a role in disease development. Based on the current knowledge on the enteric virome, in relation to celiac disease pathophysiological evolvement, the current review summarizes the potential interphases between the two. Exploring and understanding the role of the enteric virome in gluten-dependent enteropathy might bring new therapeutic strategies to change the luminal eco-event for the patient’s benefit.

The Revival of the Battle between David and Goliath in the Enteric Viruses and Microbiota Struggle: Potential Implication for Celiac Disease

The human gut is inhabited by overcrowded prokaryotic communities, a major component of which is the virome, comprised of viruses, bacteriophages, archaea, eukaryotes and bacteria. The virome is required for luminal homeostasis and, by their lytic or synergic capacities, they can regulate the microbial community structure and activity. Dysbiosis is associated with numerous chronic human diseases. Since the virome can impact microbial genetics and behavior, understanding its biology, composition, cellular cycle, regulation, mode of action and potential beneficial or hostile activities can change the present paradigm of the cross-talks in the luminal gut compartment. Celiac disease is a frequent autoimmune disease in which viruses can play a role in disease development. Based on the current knowledge on the enteric virome, in relation to celiac disease pathophysiological evolvement, the current review summarizes the potential interphases between the two. Exploring and understanding the role of the enteric virome in gluten-dependent enteropathy might bring new therapeutic strategies to change the luminal eco-event for the patient's benefit.

Serologic Diagnosis of Celiac Disease: New Biomarkers

Most patients affected by celiac disease (CD) are asymptomatic or hyposymptomatic and undiagnosed, and are at risk of preventable complications. Therefore, early diagnosis is highly recommended. Multiple diagnostic antibodies are available; the most frequently used is IgA to tissue transglutaminase (IgA-tTg). It may yield false results and, alone, does not address IgA deficiency. Recently, a new generation of anti-neo-epitope tTg check (IgG + IgA) has become available. It is highly sensitive and specific, covers IgA-deficient patients with CD, reflects intestinal damage, and has predictive potential in the diagnosis of CD.

Probiotics: If It Does Not Help It Does Not Do Any Harm. Really?

Probiotics per definition should have beneficial effects on human health, and their consumption has tremendously increased in the last decades. In parallel, the amount of published material and claims for their beneficial efficacy soared continuously. Recently, multiple systemic reviews, meta-analyses, and expert opinions expressed criticism on their claimed effects and safety. The present review describes the dark side of the probiotics, in terms of problematic research design, incomplete reporting, lack of transparency, and under-reported safety. Highlighted are the potential virulent factors and the mode of action in the intestinal lumen, risking the physiological microbiome equilibrium. Finally, regulatory topics are discussed to lighten the heterogeneous guidelines applied worldwide. The shift in the scientific world towards a better understanding of the human microbiome, before consumption of the probiotic cargo, is highly endorsed. It is hoped that better knowledge will extend the probiotic repertoire, re-confirm efficacy or safety, establish their efficacy and substantiate their beneficial effects.

Immunoreactivity of Gluten-Sensitized Sera Toward Wheat, Rice, Corn, and Amaranth Flour Proteins Treated With Microbial Transglutaminase

The aim of this study was to analyze the effects of microbial transglutaminase (mTG) on the immunoreactivity of wheat and gluten-free cereals flours to the sera of patients with celiac disease (CD) and non-celiac gluten sensitivity (NCGS). Both doughs and sourdoughs, the latter prepared by a two-step fermentation with Lactobacillus sanfranciscensis and Candida milleri, were studied. In order to evaluate the IgG-binding capacity toward the proteins of the studied flours, total protein as well as protein fractions enriched in albumins/globulins, prolamins and glutelins, were analyzed by SDS-PAGE and enzyme-linked immunosorbent assay (ELISA). Results showed that while mTG modified both gluten and gluten-free flour by increasing the amount of cross-linked proteins, it did not affect the serum's immune-recognition. In fact, no significant differences were observed in the immunoreactivity of sera from CD and NCGS patients toward wheat and gluten-free protein extracts after enzyme treatment, nor did this biotechnological treatment affect the immunoreactivity of control samples or the sera of healthy patients. These results suggest that mTG may be used as a tool to create innovative gluten and gluten-free products with improved structural properties, without increasing the immune-reactivity toward proteins present either in doughs or in sourdoughs.

Navigating the Gluten-Free Boom: The Dark Side of Gluten Free Diet

In gluten dependent conditions the gluten free diet is the cornerstone of therapy, decreasing disease activity, improving health and quality of life and treating or preventing the associated complications. Gluten withdrawal implies strict and lifelong elimination not only of wheat, barley, rye, and wheat-contaminated oats, but also of numerous non-nutritional products where components of wheat are often added. Due to multiple reasons the diet is difficult to follow and the long-term adherence is decreased with time. The present review summarizes the dark side of gluten restriction where nutritional deficiencies, toxicity, morbidity, mortality, and mental health problems are reported. The aim being to increase awareness, avoid, detect and treat the side effects and to promote a healthier nutrition, for the patient's benefits.