Latiglutenase Improves Symptoms in Seropositive Celiac Disease Patients While on a Gluten-Free Diet

Celiac disease and nonceliac enteropathies

PURPOSE OF REVIEW

This review highlights recent research in the field of celiac disease.

RECENT FINDINGS

Epidemiological studies continue to identify celiac disease-associated diseases such as inflammatory arthritis, irritable bowel syndrome, and cardiovascular disease. Recently published consensus guidelines provide recommendations for the long-term management and monitoring of patients with celiac disease. There are multiple pharmaceutical therapies for celiac disease under investigation, and recent phase I and phase II trials are reviewed here. Finally, a recent trial of patients with nonceliac gluten sensitivity demonstrates a significant nocebo effect in this condition.

SUMMARY

Recent advances in celiac disease include the development of new clinical guidelines as well as promising new therapeutics. Continued high-quality research is needed to improve the outcomes of patients with celiac disease and nonceliac enteropathies.

Beyond the gluten-free diet: Innovations in celiac disease therapeutics

Celiac disease (CD) is an autoimmune disorder exacerbated by the ingestion of gluten in genetically susceptible individuals, leading to intestinal inflammation and damage. This chronic disease affects approximately 1% of the world's population and is a growing health challenge due to its increasing prevalence. The development of CD is a complex interaction between genetic predispositions and environmental factors, especially gluten, culminating in a dysregulated immune response. The only effective treatment at present is a strict, lifelong gluten-free diet. However, adherence to this diet is challenging and often incomplete, so research into alternative therapies has intensified. Recent advances in understanding the molecular and immunological aspects of CD have spearheaded the development of novel pharmacologic strategies that should provide more effective and manageable treatment options. This review examines the latest innovations in CD therapies. The focus is on drugs in advanced clinical phases and targeting specific signaling pathways critical to the disease pathogenesis. We discuss both quantitative strategies such as enzymatic degradation of gluten, and qualitative approaches including immunomodulation and induction of gluten tolerance. Innovative treatments currently under investigation include transglutaminase inhibitors, which prevent the modification of gluten peptides, and nanoparticle-based therapies to recalibrate the immune response. These new therapies not only promise to improve patient outcomes but are also expected to improve quality of life by reducing the burden of dietary restrictions. The integration of these new therapies could revolutionize the treatment of CD and shift the paradigm from strict dietary restrictions to a more flexible and patient-friendly therapeutic approach. This review provides a comprehensive overview of the future prospects of CD treatment and emphasizes the importance of continued research and multidisciplinary collaboration to integrate these advances into standard clinical practice.

Coeliac Disease in Children-A Clinical Review Including Novel Treatment Agents

Coeliac disease (CD) affects almost of 1% of the population, yet remains undiagnosed in the majority. Though the demonstration of enteropathy in duodenal biopsy was traditionally the essential criterion for the diagnosis of coeliac disease, the guidelines published by the European Society of Paediatric Gastroenterology and Nutrition (ESPGHAN) in 2012, and revised in 2020, paved the way to a no-biopsy approach to diagnosis. In a select group of children meeting certain criteria, a definitive diagnosis of CD can now be made without the need for duodenal biopsies. This is being increasingly applied in clinical practice. It is well established that untreated coeliac disease is associated with several chronic adverse health conditions. At present, a strict gluten-free diet remains the only effective treatment for CD. The advances in our understanding of the pathogenesis of CD have led to a search for alternative treatment agents. Several investigational agents are in various phases of clinical trials at present. In this review, we outline the clinical aspects of coeliac disease and summarise various investigational treatment agents.

New developments in celiac disease treatments

Celiac disease (CeD), an autoimmune disorder triggered by gluten, affects around 1% of the global population. Standard treatment is a strict gluten-free diet (GFD), which poses significant challenges due to dietary restrictions, cross-contamination and subsequent persistent intestinal inflammation. This underscores the need for new treatment options addressing the complex pathophysiology of CeD. Recent research focuses on developing drugs that target intestinal barrier regeneration, gluten peptide modification, immune response alteration, and gut microbial ecosystem modulation. These approaches offer potential for more effective management of CeD beyond GFD. Gluten-independent treatments may be particularly relevant under the FDA's draft guidance for CeD, which emphasizes drug development as an adjunct to GFD for patients with ongoing signs and symptoms of CeD despite strict GFD.

A Composite Morphometric Duodenal Biopsy Mucosal Scale for Celiac Disease Encompassing Both Morphology and Inflammation

BACKGROUND & AIMS

Villus height to crypt depth ratio (Vh:Cd) and intraepithelial lymphocytes (IEL) are key measures of histology of the small intestine in celiac disease. Although the field of celiac disease has advanced, there remains no broadly accepted measure of mucosal injury. We assessed whether a composite Vh:Cd and IEL scale (VCIEL) can improve accuracy and statistical precision for assessing histology, compared with individual measures.

METHODS

The formulation of the VCIEL composite histologic scale was based on combining the Vh:Cd and IEL measurements for individual patients with equal weighting, by converting each scale to a fraction of their standard deviation and summing the results. The VCIEL formula was applied to several clinical trials and the results for Vh:Cd and IEL were compared with those for VCIEL with regards to clinical significance (effect size) and statistical significance.

RESULTS

For the ALV003-1021 trial, we observed an effect size and P value (analysis of covariance) of 1.37 and 0.038 for ΔVh:Cd, 1.17 and 0.005 for ΔIEL, and 1.86 and 0.004 for ΔVCIEL. For the similar gluten-challenge IMGX003-NCCIH-1721 trial, the corresponding results were 0.76 and 0.057 for ΔVh:Cd, 0.98 and 0.018 for ΔIEL, and 1.14 and 0.007 for ΔVCIEL. Similar improvements with the use of VCIEL over individual Vh:Cd and IEL measures were observed for other studies, including a nontherapeutic gluten challenge study.

CONCLUSIONS

The composite VCIEL scale combining Vh:Cd and IEL values seems to improve accuracy and statistical precision compared with either component alone.

Celiac disease: Hope for new treatments beyond a gluten-free diet

BACKGROUND & AIMS

Celiac disease (CD) is a chronic inflammatory disease of the small intestine induced and maintained by gluten ingestion in susceptible individuals. Current treatment consists of strict adherence to a lifelong gluten-free diet (GFD) which is considered safe and effective in the large majority of patients. However, since adherence to a GFD is difficult and has a negative impact on quality of life, an increasing interest in other treatment options has emerged. Moreover, in some individuals a GFD is not sufficiently effective, necessitating alternative treatments.

METHODS

By performing a systematic search, we constructed a detailed narrative review. Only treatment options considered relevant and conducted in a phase I, II or III clinical trial were included.

RESULTS

Based on the pathophysiology of CD, four major therapeutic approaches can be distinguished: firstly, by focusing on intraluminal gluten detoxification before absorption occurs, secondly, by modulating intestinal permeability and preventing paracellular uptake, thirdly, by enhancing immunological tolerance to gluten and finally, by regulating gluten auto-immunity.

CONCLUSIONS

Despite significant efforts, no treatment has yet completed a phase III clinical trial. Future studies will likely focus on the use of supplemental drugs in conjunction to a GFD, with ALV003 and ZED-1227 currently being the most promising therapeutic options.

Risk of Gluten Cross-Contamination Due to Food Handling Practices: A Mini-Review

Celiac disease (CD) is an autoimmune disease triggered by the ingestion of gluten in genetically predisposed individuals, affecting 1.4% of the world population. CD induces an inflammatory reaction that compromises small intestine villi, leading to nutrient malabsorption, and gastro and extraintestinal manifestations. Although other treatment approaches are being studied, adherence to a gluten-free diet (GFD) is the only effective intervention to date. Despite this, about 50% of patients experience persistent inflammation, often associated with unintentional gluten ingestion through contaminated food. There are regulations for labeling gluten-free foods which specify a limit of 20 mg/kg (20 ppm). The risks of gluten cross-contamination above that level are present throughout the whole food production chain, emphasizing the need for caution. This review explores studies that tested different procedures regarding the shared production of gluten-containing and gluten-free food, including the use of shared equipment and utensils. A literature review covering PubMed, Scielo, Web of Science, VHL and Scopus identified five relevant studies. The results indicate that shared environments and equipment may not significantly increase gluten cross-contamination if appropriate protocols are followed. Simultaneous cooking of gluten-containing and gluten-free pizzas in shared ovens has demonstrated a low risk of contamination. In general, shared kitchen utensils and equipment (spoon, ladle, colander, knife, fryer, toaster) in controlled experiments did not lead to significant contamination of samples. On the other hand, cooking gluten-free and gluten-containing pasta in shared water resulted in gluten levels above the established limit of 20 ppm. However, rinsing the pasta under running water for a few seconds was enough to reduce the gluten content of the samples to less than 20 ppm.

Gluten-Free Diet and Other Celiac Disease Therapies: Current Understanding and Emerging Strategies

A lifelong gluten-free diet (GFD) is the only treatment for celiac disease and other gluten-related disorders. Nevertheless, strict adherence to the GFD is often challenging due to concerns about social isolation, risk of gluten contaminations, high cost, poor quality and the taste of gluten-free products. Moreover, although the GFD is effective in achieving mucosal healing, it may lead to dietary imbalances due to nutrient deficiencies over a long period of time. To overcome these issues, several gluten-free wheat flours have been developed to create products that closely resemble their gluten-containing counterparts. Furthermore, given the critical importance of adhering to the GFD, it becomes essential to promote adherence and monitor possible voluntary or involuntary transgressions. Various methods, including clinical assessment, questionnaires, serology for celiac disease, duodenal biopsies and the detection of Gluten Immunogenic Peptides (GIPs) are employed for this purpose, but none are considered entirely satisfactory. Since adherence to the GFD poses challenges, alternative therapies should be implemented in the coming years to improve treatment efficacy and the quality of life of patients with celiac disease. The aim of this narrative review is to explore current knowledge of the GFD and investigate its future perspectives, focusing on technology advancements, follow-up strategies and insights into a rapidly changing future.

Standardizing Randomized Controlled Trials in Celiac Disease: An International Multidisciplinary Appropriateness Study

BACKGROUND & AIMS

There is a need to develop safe and effective pharmacologic options for the treatment of celiac disease (CeD); however, consensus on the appropriate design and configuration of randomized controlled trials (RCTs) in this population is lacking.

METHODS

A 2-round modified Research and Development/University of California Los Angeles Appropriateness Method study was conducted. Eighteen gastroenterologists (adult and pediatric) and gastrointestinal pathologists voted on statements pertaining to the configuration of CeD RCTs, inclusion and exclusion criteria, gluten challenge, and trial outcomes. Two RCT designs were considered, representing the following distinct clinical scenarios for which pharmacotherapy may be used: trials incorporating a gluten challenge to simulate exposure; and trials evaluating reversal of histologic changes, despite attempted adherence to a gluten-free diet. Each statement was rated as appropriate, uncertain, or inappropriate, using a 9-point Likert scale.

RESULTS

For trials evaluating prevention of relapse after gluten challenge, participants adherent to a gluten-free diet for 12 months or more with normal or near-normal-sized villi should be enrolled. Gluten challenge should be FODMAPS (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) free, and efficacy evaluated using histology with a secondary patient-reported outcome measure. For trials evaluating reversal of villus atrophy, the panel voted it appropriate to enroll participants with a baseline villus height to crypt depth ratio ≤2 and measure efficacy using a primary histologic end point. Guidance for measuring histologic, endoscopic, and patient-reported outcomes in adult and pediatric patients with CeD are provided, along with recommendations regarding the merits and limitations of different end points.

CONCLUSIONS

We developed standardized recommendations for clinical trial design, eligibility criteria, outcome measures, gluten challenge, and disease evaluations for RCTs in patients with CeD.

Specificity Enhancement of Glutenase Bga1903 toward Celiac Disease-Eliciting Pro-Immunogenic Peptides via Active-Site Modification

Celiac disease is an autoimmune disease triggered by oral ingestion of gluten, with certain gluten residues resistant to digestive tract enzymes. Within the duodenum, the remaining peptides incite immunogenic responses, including the generation of autoantibodies and inflammation, leading to irreversible damage. Our previous exploration unveiled a glutenase called Bga1903 derived from the Gram-negative bacterium Burkholderia gladioli. The cleavage pattern of Bga1903 indicates its moderate ability to mitigate the toxicity of pro-immunogenic peptides. The crystal structure of Bga1903, along with the identification of subsites within its active site, was determined. To improve its substrate specificity toward prevalent motifs like QPQ within gluten peptides, the active site of Bga1903 underwent site-directed mutagenesis according to structural insights and enzymatic kinetics. Among the double-site mutants, E380Q/S387L exhibits an approximately 34-fold increase in its specificity constant toward the QPQ sequence, favoring glutamines at the P1 and P3 positions compared to the wild type. The increased specificity of E380Q/S387L not only enhances its ability to break down pro-immunogenic peptides but also positions this enzyme variant as a promising candidate for oral therapy for celiac disease.

Emerging Pharmaceutical Therapies to Address the Inadequacy of a Gluten-Free Diet for Celiac Disease

Celiac disease (CeD) is a chronic autoimmune disorder triggered by the ingestion of gluten, affecting around 1% of the global population. It is a multifactorial disease involving both genetics and environmental factors. Nowadays, the only available treatment for CeD is a life-long gluten-free diet (GFD), which can cause a significant burden for patients, since symptoms and mucosal injury can persist despite apparent compliance with a GFD. This could also lead to psychological consequences and affect the quality of life of these patients. Thankfully, recent advances in understanding the pathogenesis of CeD and the availability of various targets have made it feasible to explore pharmaceutical treatments specific to CeD. Recently, the FDA has highlighted the unmet needs of adult patients on a GFD who experience ongoing symptoms attributed to CeD and also show persistent duodenal villous atrophy. This review will outline the limitations of a GFD, describe the targets of potential novel treatment of CeD and provide an overview of the primary clinical trials involving oral and injectable agents for a non-dietary treatment of CeD.

Dynamics of Serologic Change to Gluten in Celiac Disease Patients

Serologic measures of tissue transglutaminase (tTG) immunoglobulin A (IgA) and deamidated gliadin peptide (DGP) IgA and immunoglobulin G (IgG) are hallmark tests utilized when diagnosing individuals for celiac disease (CeD) and for monitoring adherence to a gluten-free diet (GFD), currently the only available treatment for CeD. We address two issues in this study: (i) the relapse to seropositivity for CeD patients who resume a gluten containing diet and (ii) the correlation between two different tTG-IgA assays near the upper limit of normal (ULN) designated thresholds. Regarding the first issue, often a suspected CeD individual is put back on a gluten diet to return to their serologic levels. However, we show it requires a substantial amount of gluten for serology to return to a positive level. For example, in one study of 22 patients treated with placebo and taking 84 g of gluten over 6 weeks, only two converted from seronegative to seropositive for tTG-IgA. Regarding the second topic, we compare the relationship for different serologic assays, namely tTG-IgA AB (recombinant, ULN = 4 units/mL) vs. tTG-IgA (non-recombinant, ULN = 20 units). There is a strong correlation between both measurements as evidenced by a Pearson coefficient of R = 0.8584; however, we observed that the cross-correlation in terms of sensitivity and specificity improved substantially by using an ULN value of three instead of four for the tTG-IgA AB (recombinant) assay. This result suggests that assay thresholds used for initial diagnosis in patients who have not yet started a GFD may need to be adjusted for monitoring and in the setting of a diagnostic gluten challenge.

Celiac disease: mechanisms and emerging therapeutics

Celiac disease (CeD) is a widespread, gluten-induced, autoimmune disorder that lacks any medicinal therapy. Towards the goal of developing non-dietary treatments for CeD, research has focused on elucidating its molecular and cellular etiology. A model of pathogenesis has emerged centered on interactions between three molecular families: specific class II MHC proteins on antigen-presenting cells (APCs), deamidated gluten-derived peptides, and T cell receptors (TCRs) on inflammatory CD4+ T cells. Growing evidence suggests that this pathogenic axis can be pharmacologically targeted to protect patients from some of the adverse effects of dietary gluten. Further studies have revealed the existence of additional host and environmental contributors to disease initiation and tissue damage. This review summarizes our current understanding of CeD pathogenesis and how it is being harnessed for therapeutic design and development.

Serological Investigation of Persistent Villous Atrophy in Celiac Disease

INTRODUCTION

Persistent villous atrophy (VA) is not uncommon in celiac disease (CeD) while patients take a gluten-free diet (GFD).

METHODS

We conducted a retrospective study with 122 serum samples collected from controls and patients with CeD either at the initial diagnosis or at the follow-up during endoscopy. These samples were assigned to 3 groups: nonceliac control, non-VA CeD (Marsh score 0-2), and VA CeD (Marsh score 3a-3c). We established an in-house multiplex assay to identify potential serological biomarkers for VA. We assessed autoantibodies reported to affect the small intestine, including IgA and IgG antibodies against tissue transglutaminase (tTG), interferons, villin, actin, autoimmune enteropathy-related 75 kDa antigen (AIE-75), and tryptophan hydroxylase (TPH)-1, as well as 27 cytokines. The apolipoproteins quantified included apo A1, apo B-100, and apo A4, which were produced predominantly by the intestinal epithelium or expressed specifically in villi.

RESULTS

Autoantibody levels were high only for tTG antibodies, which performed well in initial CeD diagnosis, but suboptimally for VA prediction during follow-up, because 14.6% of the follow-up patients with VA had low tTG-IgA. Increasing dilution improved tTG-IgA quantification, particularly when the antibody levels were extremely high but did not significantly improve VA detection. Among those with low tTG-IgA and persistent VA, high proinflammatory cytokines were observed in 2 patients. Median low-density lipoprotein cholesterol levels were significantly lower in the VA CeD group ( P = 0.03). Apolipoprotein levels were similar in patients with and without VA but diverged between those on a GFD or not.

DISCUSSION

tTG-IgA as a biomarker is suboptimal for VA prediction while on a GFD. Persistent VA is associated with low low-density lipoprotein cholesterol levels and partially related to persistent high proinflammatory cytokines.

Old and New Adjunctive Therapies in Celiac Disease and Refractory Celiac Disease: A Review

Celiac disease (CD) is a chronic enteropathy caused by the ingestion of gluten in a genetically susceptible individual. Currently, a gluten-free diet (GFD) is the only recommended treatment. However, unintentional gluten ingestion or a persistent villous atrophy with malabsorption (regardless of a strict GFD) as in the case of Refractory Celiac Disease (RCD) represents a major issue. In this review, we have analysed and discussed data from both randomized controlled trials and observational studies concerning adjunctive therapies as well as novel therapies for the treatment of CD and RCD. The literature search was carried out through Medline and Scopus. In total, 2268 articles have been identified and 49 were included in this review (36 studies resulting from the search strategy and 13 from other sources). Today, GFD remains the only effective treatment, although steroids, mesalamine, and more recently biological therapies have found space in the complex management of RCD. Currently, studies evaluating the effectiveness of novel therapies are still limited and preliminary results have been controversial.

Analytical and functional approaches to assess the immunogenicity of gluten proteins

Gluten proteins are the causative agents of celiac disease (CD), a lifelong and worldwide spread food intolerance, characterized by an autoimmune enteropathy. Gluten is a complex mixture of high homologous water-insoluble proteins, characterized by a high content of glutamine and proline amino acids that confers a marked resistance to degradation by gastrointestinal proteases. As a consequence of that, large peptides are released in the gut lumen with the potential to activate inflammatory T cells, in CD predisposed individuals. To date, several strategies aimed to detoxify gluten proteins or to develop immunomodulatory drugs to recover immune tolerance to gluten are under investigation. This review overviews the state of art of both analytical and functional methods currently used to assess the immunogenicity potential of gluten proteins from different cereal sources, including native raw seed flours and complex food products, as well as drug-treated samples. The analytical design to assess the content and profile of gluten immunogenic peptides, described herein, is based on the oral-gastro-intestinal digestion (INFOGEST model) followed by extensive characterization of residual gluten peptides by proteomic and immunochemical analyses. These approaches include liquid chromatography-high-resolution mass spectrometry (LC-MS/MS) and R5/G12 competitive ELISA. Functional studies to assess the immune stimulatory capabilities of digested gluten peptides are based on gut mucosa T cells or peripheral blood cells obtained from CD volunteers after a short oral gluten challenge.

New Developments in Celiac Disease Treatment

Celiac disease (CD) is a common autoimmune disease affecting around 1% of the population. It consists of an immune-mediated enteropathy, triggered by gluten exposure in susceptible patients. All patients with CD, irrespective of the presence of symptoms, must endure a lifelong gluten-free diet (GFD). This is not an easy task due to a lack of awareness of the gluten content in foods and the extensive incorporation of gluten in processed foods. Furthermore, a GFD imposes a sense of limitation and might be associated with decreased quality of life in CD patients. This results in gluten contamination in the diet of four out of five celiac patients adhering to a GFD. Furthermore, one in three adult patients will report persistent symptoms and two in three will not achieve full histological recovery when on a GFD. In recent years, there has been extensive research conducted in the quest to find the holy grail of pharmacological treatment for CD. This review will present a concise description of the current rationale and main clinical trials related to CD drug therapy.

Latiglutenase Protects the Mucosa and Attenuates Symptom Severity in Patients With Celiac Disease Exposed to a Gluten Challenge

BACKGROUND & AIMS

Gluten ingestion in patients with celiac disease can lead to gastrointestinal symptoms and small intestinal mucosal injury.

METHODS

This gluten challenge phase 2 trial was double blind and placebo controlled, and it assessed the efficacy and safety of a 1200-mg dose of IMGX003 in patients with celiac disease exposed to 2 g of gluten per day for 6 weeks. The change in the ratio of villus height to crypt depth was the primary endpoint. Secondary endpoints included density of intraepithelial lymphocytes and symptom severity. These endpoints were evaluated by analysis of covariance. Additional endpoints included serology and gluten-immunogenic peptides in urine.

RESULTS

Fifty patients were randomized, and 43 patients completed the study (IMGX003, n = 21; placebo, n = 22). The mean change in the ratio of villus height to crypt depth (primary endpoint) for IMGX003 vs placebo was -0.04 vs -0.35 (P = .057). The mean change in the density of intraepithelial lymphocytes (secondary endpoint) for IMGX003 vs placebo was 9.8 vs 24.8 cells/mm epithelium (P = .018). The mean change (worsening) in symptom severity in relative units (secondary endpoint) for IMGX003 vs placebo was 0.22 vs 1.63 (abdominal pain, P = .231), 0.96 vs 3.29 (bloating, P = .204), and 0.02 vs 3.20 (tiredness, P = .113). The 3 × 2-week trend line significance values for these symptoms, respectively, were P = .014, .030, and .002.

CONCLUSIONS

IMGX003 reduced gluten-induced intestinal mucosal damage and symptom severity. (ClinicalTrials.gov, Number: NCT03585478).

A Comprehensive Review of the Neurological Manifestations of Celiac Disease and Its Treatment

Celiac disease (CD) is a common chronic inflammatory disorder occurring in genetically predisposed individuals secondary to gluten ingestion. CD usually presents with gastrointestinal symptoms such as pain, bloating, flatulence, and constipation or diarrhea. However, individuals can present in a nonclassical manner with only extraintestinal symptoms. The neurological manifestations of CD include ataxia, cognitive impairment, epilepsy, headache, and neuropathy. A lifelong gluten-free diet is the current recommended treatment for CD. This review discusses the relevant neurological manifestations associated with CD and the novel therapeutics. Further research is required to get a better understanding of the underlying pathophysiology of the neurological manifestations associated with CD. Clinicians should keep CD in the differential diagnosis in individuals presenting with neurological dysfunction of unknown cause.

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.

Recombinant Cathepsin L of Tribolium castaneum and Its Potential in the Hydrolysis of Immunogenic Gliadin Peptides

Wheat gliadins contain a large amount of glutamine- and proline-rich peptides which are not hydrolyzed by human digestive peptidases and can cause autoimmune celiac disease and other forms of gluten intolerance in predisposed people. Peptidases that efficiently cleave such immunogenic peptides can be used in enzyme therapy. The stored product insect pest Tribolium castaneum efficiently hydrolyzes gliadins. The main digestive peptidase of T. castaneum is cathepsin L, which is from the papain C1 family with post-glutamine cleavage activity. We describe the isolation and characterization of T. castaneum recombinant procathepsin L (rpTcCathL1, NP_001164001), which was expressed in Pichia pastoris cells. The activation of the proenzyme was conducted by autocatalytic processing. The effects of pH and proenzyme concentration in the reaction mixture on the processing were studied. The mature enzyme retained high activity in the pH range from 5.0 to 9.0 and displayed high pH-stability from 4.0 to 8.0 at 20 °C. The enzyme was characterized according to electrophoretic mobility under native conditions, activity and stability at various pH values, a sensitivity to various inhibitors, and substrate specificity, and its hydrolytic effect on 8-, 10-, 26-, and 33-mer immunogenic gliadins peptides was demonstrated. Our results show that rTcCathL1 is an effective peptidase that can be used to develop a drug for the enzyme therapy of various types of gluten intolerance.

Review on pediatric coeliac disease from a clinical perspective

Coeliac disease is an immune-mediated condition characterized by chronic inflammation of the small bowel with villous atrophy driven by gluten ingestion in genetically predisposed individuals. It occurs frequently in both children and adults, affecting 1-4% of the population. The disease is associated with both gastrointestinal and extra-intestinal symptoms related to malabsorption and/or immune activation, and autoantibodies to tissue transglutaminase. Removal of gluten from the diet results in resolution of symptoms and enteropathy in the majority of patients. A good diagnostic work-up is important to avoid unnecessary restrictive diets in children. In this review on pediatric coeliac disease, we address epidemiology including predisposing environmental factors and possible preventive strategies, as well as the clinical presentation, diagnosis and follow-up. What is Known: •Primary prevention of coeliac disease is not possible; however, secondary prevention by targeting high-risk groups is recommended. •The diagnosis is safe without duodenal biopsies if specific conditions are met, also in asymptomatic children. What is New: •HLA-DQ typing is not routinely required for the diagnosis, whereas it can rule out coeliac disease if HLA-DQ2 and HLA-DQ8 are absent. •Follow-up could be improved by a more rational use of (laboratory) tests, increased intention to dietary compliance and quality of life.

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.

How does a celiac iceberg really float? The relationship between celiac disease and gluten

Celiac disease (CD) is an autoimmune intestinal disease caused by intolerance of genetically susceptible individuals after intake of gluten-containing grains (including wheat, barley, etc.) and their products. Currently, CD, with "iceberg" characteristics, affects a large population and is distributed over a wide range of individuals. This present review summarizes the latest research progress on the relationship between CD and gluten. Furthermore, the structure and function of gluten peptides related to CD, gluten detection methods, the effects of processing on gluten and gluten-free diets are emphatically reviewed. In addition, the current limitations in CD research are also discussed. The present work facilitates a comprehensive understanding of CD as well as gluten, which can provide a theoretical reference for future research.

Relative Rates of Gluten Digestion by Nine Commercial Dietary Digestive Supplements

Endopeptidases containing supplements may digest gluten and reduce the impact on celiac and gluten-sensitive subjects who inadvertently consume gluten. We investigated the relative rate of disappearance of coeliac relevant epitopes in extracts of nine commercial supplements, using two competitive enzyme-linked immunosorbent assays (ELISAs)—Ridascreen (detects QQPFP, QQQFP, LQPFP, and QLPFP) and Gluten-Tec (detects Glia-α20 and PFRPQQPYPQ). All epitopes are destroyed by cleavage after P and Q amino acids. Rates at pH 3.5 and pH 7.0 were measured. These experiments were designed to measure relative rates of epitope digestion not to mimic in vivo digestion. The supplements were: 1 GluteGuard, 2 GlutenBlock, 3 GliadinX, 4 GlutnGo, 5 GlutenRescue, 6 Eat E-Z Gluten+, 7 Glutenease, 8 Glutezyme, and 9 Gluten Digest. The mean initial rate and half-lives of epitope digestion were deduced and extrapolated to rates at the recommended dose of one supplement in a fasting stomach volume. At pH 7, supplement 1 was the fastest acting of the supplements, with Ridascreen ELISA, more than twice as fast as the next fastest supplements, 5, 6, 7, and 8. Supplements 2, 3, and 4 showed little activity at pH 7.0. Supplement 1 was also the fastest acting at pH 7 with Gluten-Tec ELISA, more than three times the rate for supplements 2 and 3, with supplements 4–9 showing minimal activity. At pH 3.5, supplement 1 acted more than five times as fast as the next fastest supplements, 2 and 3, when measured by Ridascreen, but supplements 2 and 3 were over two times faster than supplement 1 when measured by Gluten-Tec. Supplements 4–9 demonstrated minimal activity at pH 3.5 with either ELISA. Supplement 1 most rapidly digested the key immuno-reactive gluten epitopes identified by the R5 antibody in the Codex-approved competitive Ridascreen ELISA method and associated with the pathology of celiac disease.

Effective Degradation of Gluten and Its Fragments by Gluten-Specific Peptidases: A Review on Application for the Treatment of Patients with Gluten Sensitivity

To date, there is no effective treatment for celiac disease (CD, gluten enteropathy), an autoimmune disease caused by gluten-containing food. Celiac patients are supported by a strict gluten-free diet (GFD). However, in some cases GFD does not negate gluten-induced symptoms. Many patients with CD, despite following such a diet, retain symptoms of active disease due to high sensitivity even to traces of gluten. In addition, strict adherence to GFD reduces the quality of life of patients, as often it is difficult to maintain in a professional or social environment. Various pharmacological treatments are being developed to complement GFD. One promising treatment is enzyme therapy, involving the intake of peptidases with food to digest immunogenic gluten peptides that are resistant to hydrolysis due to a high prevalence of proline and glutamine amino acids. This narrative review considers the features of the main proline/glutamine-rich proteins of cereals and the conditions that cause the symptoms of CD. In addition, we evaluate information about peptidases from various sources that can effectively break down these proteins and their immunogenic peptides, and analyze data on their activity and preliminary clinical trials. Thus far, the data suggest that enzyme therapy alone is not sufficient for the treatment of CD but can be used as a pharmacological supplement to GFD.

Gluten Degradation, Pharmacokinetics, Safety, and Tolerability of TAK-062, an Engineered Enzyme to Treat Celiac Disease

BACKGROUND AND AIMS

Celiac disease (CeD) is an immune-mediated disorder triggered by the ingestion of gluten. Despite adhering to a gluten-free diet (the only management option available to patients with CeD), many patients continue to experience symptoms and intestinal injury. Degradation of immunogenic fractions of gluten peptides in the stomach has been proposed as an approach to reduce toxicity of ingested gluten; however, no enzymes evaluated to date have demonstrated sufficient gluten degradation in complex meals. TAK-062 is a novel, computationally designed endopeptidase under development for the treatment of patients with CeD.

METHODS

Pharmacokinetics, safety, and tolerability of TAK-062 100-900 mg were evaluated in a phase I dose escalation study in healthy participants and patients with CeD. Gluten degradation by TAK-062 was evaluated under simulated gastric conditions in vitro and in healthy participants in the phase I study, with and without pretreatment with a proton pump inhibitor. Residual gluten (collected through gastric aspiration in the phase I study) was quantified using R5 and G12 monoclonal antibody enzyme-linked immunosorbent assays.

RESULTS

In vitro, TAK-062 degraded more than 99% of gluten (3 g and 9 g) within 10 minutes. In the phase I study, administration of TAK-062 was well tolerated and resulted in a median gluten degradation ranging from 97% to more than 99% in complex meals containing 1-6 g gluten at 20-65 minutes postdose.

CONCLUSIONS

TAK-062 is well tolerated and rapidly and effectively degrades large amounts of gluten, supporting the development of this novel enzyme as an oral therapeutic for patients with CeD. (ClinicalTrials.gov: NCT03701555, https://clinicaltrials.gov/ct2/show/NCT03701555.).

New Insights into Non-Dietary Treatment in Celiac Disease: Emerging Therapeutic Options

To date, the only treatment for celiac disease (CD) consists of a strict lifelong gluten-free diet (GFD), which has numerous limitations in patients with CD. For this reason, dietary transgressions are frequent, implying intestinal damage and possible long-term complications. There is an unquestionable need for non-dietary alternatives to avoid damage by involuntary contamination or voluntary dietary transgressions. In recent years, different therapies and treatments for CD have been developed and studied based on the degradation of gluten in the intestinal lumen, regulation of the immune response, modulation of intestinal permeability, and induction of immunological tolerance. In this review, therapeutic lines for CD are evaluated with special emphasis on phase III and II clinical trials, some of which have promising results.

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.

Current and emerging therapies for coeliac disease

Coeliac disease is a common enteropathy that occurs in genetically susceptible individuals in response to the ingestion of gluten proteins present in wheat, rye and barley. Currently, the only available treatment for the condition is a strict, life-long gluten-free diet that, despite being safe and often effective, is associated with several challenges. Due to the high cost, particularly restrictive nature and perception of decreased quality of life associated with the diet, some patients are continuously exposed to gluten, which prevents an adequate disease control. Moreover, a subgroup of patients does not respond to the diet adequately, and healing of the small-bowel mucosa can be incomplete. Thus, there is a need for alternative treatment forms. The increasingly understood pathogenetic process of coeliac disease has enabled the identification of various targets for future therapies. Multiple investigational therapies ranging from tolerogenic to immunological approaches are in the pipeline, and several drug candidates have entered phase II/III clinical trials. This Review gives a broad overview of the different investigative treatment modalities for coeliac disease and summarizes the latest advances in this field.

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.

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.

Rationally engineered prolyl endopeptidases from Sphingomonas capsulata with improved hydrolytic activity towards pathogenic peptides of celiac diseases

Celiac disease affects approximately 1% of the population and is a major public health problem worldwide. It is trigged by gluten-derived peptides, which have unusually high proline-glutamine motif content and are highly resistant to proteolysis by digestive enzymes of the gastrointestinal tract. The only treatment for celiac disease is strict, lifelong adherence to a gluten-free diet, which is effective but costly and difficult to maintain. Therefore, novel non-dietary therapies for celiac disease are urgently needed. Gluten-degrading enzymes are promising non-dietary treatments, and some enzymes have been investigated in preclinical or clinical studies. A combination of prolyl endopeptidase from Sphingomonas capsulata (SC PEP) and a glutamine-specific endoprotease (EP-B2 from barley) known as latiglutenase showed insufficient benefits in phase II clinical trials, likely because of its low enzyme activity in the gastric environment. Therefore, improving enzyme activity is essential for the clinical application of SC PEP. Enzyme activity can be enhanced using computer-aided rational protein design tools. In this study, we combined molecular docking and molecular dynamics simulation to rationally design SC PEP mutants and experimentally evaluated their activities. We identified mutants with up to 90-103% increases in specific activity and up to 80-202% increases in the catalytic rate. We have investigated the mechanism underlying the enhanced activity of these mutants, and found that a conformational transition of the β-propeller domain and catalytic domain of SC PEP was important for enzyme activity, and this transition was affected by residues in the catalytic domain and at the domain interface; a shorter distance between the substrate Pro and the oxyanion holes was also crucial for improving SC PEP catalytic activity. Our results provide useful information for the rational design of highly active SC PEPs to accelerate the development of enzyme therapeutics candidates for Celiac disease.

A Comprehensive Review of Celiac Disease/Gluten-Sensitive Enteropathies

Celiac disease is a complex immune-mediated gluten-sensitive enteropathy with protean clinical manifestations. It is manifest in genetically predisposed individuals who ingest gluten in varying amounts. In broad terms, it is thought to affect 1% of the population in the USA. More specifically, the prevalence increases drastically from 1:133 in patients not-at-risk, to 1:56 in symptomatic patients, to 1:39 in patients with a second-degree relative with the diagnosis, and to 1:22 in patients with a first-degree relative with the diagnosis. It may be associated with several immune-mediated phenomena, autoimmune diseases, and complicated by vitamin and other trace element deficiencies, bone disease, and malignancy. Our understanding of celiac disease has evolved rapidly over the past two decades. This has led to several lines of enquiry on the condition and potential treatment options. More recently, several entities including gluten intolerance, non-celiac gluten sensitivity, and seronegative celiac disease have been described. These conditions are distinct from allergies or intolerance to wheat or wheat products. There are challenges in defining some of these entities since a large number of patients self-report these conditions. The absence of confirmatory diagnostic tests poses an added dilemma in distinguishing these entities. The differences in spectrum of symptoms and highlights of the variability between the pediatric and adult populations have been studied in some detail. The role of screening for celiac disease is examined in both the general population and "at risk" populations. Diagnostic strategies including the best available serologic testing, utility of HLA haplotypes DQ2 and DQ8 which are seen in over 90% of patients with celiac disease as compared with approximately 40% of the general population, and endoscopic evaluation are also reviewed. Comprehensive nutritional management after diagnosis is key to sustained health in patients with celiac disease. Simple algorithms for care based on a comprehensive multidisciplinary approach are proposed. Refractory and non-responsive celiac diseases in the setting of a gluten-free diet are examined as are novel non-dietary therapies. Finally, the association of other disease states including psychiatric illness, infertility, lymphoproliferative malignancy, and mortality is explored with special attention paid to autoimmune and atopic disease.

Directed-Mutagenesis of Flavobacterium meningosepticum Prolyl-Oligopeptidase and a Glutamine-Specific Endopeptidase From Barley

Wheat gluten proteins are the known cause of celiac disease. The repetitive tracts of proline and glutamine residues in these proteins make them exceptionally resilient to digestion in the gastrointestinal tract. These indigested peptides trigger immune reactions in susceptible individuals, which could be either an allergic reaction or celiac disease. Gluten exclusion diet is the only approved remedy for such disorders. Recently, a combination of a glutamine specific endoprotease from barley (EP-B2), and a prolyl endopeptidase from Flavobacterium meningosepticum (Fm-PEP), when expressed in the wheat endosperm, were shown to reasonably detoxify immunogenic gluten peptides under simulated gastrointestinal conditions. However useful, these "glutenases" are limited in application due to their denaturation at high temperatures, which most of the food processes require. Variants of these enzymes from thermophilic organisms exist, but cannot be applied directly due to their optimum activity at temperatures higher than 37°C. Though, these enzymes can serve as a reference to guide the evolution of peptidases of mesophilic origin toward thermostability. Therefore, a sequence guided site-saturation mutagenesis approach was used here to introduce mutations in the genes encoding Fm-PEP and EP-B2. A thermostable variant of Fm-PEP capable of surviving temperatures up to 90°C and EP-B2 variant with a thermostability of up 60°C were identified using this approach. However, the level of thermostability achieved is not sufficient; the present study has provided evidence that the thermostability of glutenases can be improved. And this pilot study has paved the way for more detailed structural studies in the future to obtain variants of Fm-PEP and EP-B2 that can survive temperatures ~100°C to allow their packing in grains and use of such grains in the food industry.

Therapeutic options for coeliac disease: What else beyond gluten-free diet?

Coeliac disease is a chronic and systemic autoimmune condition triggered by gluten ingestion in genetically predisposed subjects. Currently, the only effective treatment available is a strict, lifelong gluten-free diet. However, patients perceive gluten withdrawal as an unsustainable burden in their life and some of them can exhibit persistent symptoms despite a strict diet. Thus, gluten-free diet represents a challenge, leading scientists to look for alternative or complementary treatments. This review will focus on non-dietary therapies for coeliac disease highlighting six therapeutic strategies: (1) decreasing gluten immunogenic content before it reaches the intestine; (2) sequestering gluten in the gut lumen before absorption; (3) blocking the passage of gluten through a leaky intestinal barrier; (4) preventing the enhancement of immune response against gliadin; (5) dampening the downstream immune activation; (6) inducing immune tolerance to gluten. Most developing therapies are only in the pre-clinical phase with only a few being tested in phase 2b or 3 trials. Although new approaches raise the hope for coeliacs giving them a chance to come back to gluten, for the time being a cautionary appraisal of new therapies suggests that they may have a complementary role to gluten withdrawal, mainly to prevent inadvertent gluten contamination.

Latiglutenase Treatment for Celiac Disease: Symptom and Quality of Life Improvement for Seropositive Patients on a Gluten-Free Diet

Background

Celiac disease (CD) is a widespread autoimmune disease triggered by dietary gluten that can lead to severe gastrointestinal symptoms. Because there is no available treatment other than a lifelong gluten-free diet, many patients continue to experience chronic symptoms.

Aim

In this analysis we report on the efficacy of latiglutenase, an orally administered enzyme treatment, for improving multiple gluten-induced symptoms and consequent quality of life (QOL) due to inadvertent gluten consumption.

Methods

This analysis is based on data from the CeliAction study of symptomatic patients (ALV003-1221; NCT01917630). Patients were treated with latiglutenase or placebo for 12 weeks and instructed to respond to a symptom diary daily and to multiple QOL questionnaires at weeks 0, 6, and 12 of the treatment periods as secondary endpoints. The results were stratified by serostatus.

Results

398 patients completed the 12-week CDSD study. In seropositive, but not seronegative, CD patients a statistically significant and dose-dependent improvement was seen in the severity and frequency of abdominal pain, bloating, tiredness, and constipation. In subjects receiving 900 mg latiglutenase, improvements (p-values) in the severity of these symptoms for week 12 were 58% (0.038), 44% (0.023), 21% (0.164), and 104% (0.049) respectively, relative to placebo-dosed subjects. The reduction in symptoms trended higher for more symptomatic patients. Similar results were observed for the QOL outcome measures.

Conclusions

Although this study was not powered to definitively establish the benefit of latiglutenase in seropositive CD patients, such patients appear to show symptomatic and QOL benefit from using latiglutenase with meals.

Recent advances in celiac disease and refractory celiac disease

Celiac disease (CeD), defined as gluten-induced enteropathy, is a frequent and largely underdiagnosed disease. Diagnosis relies on the detection of highly specific serum IgA anti-transglutaminase auto-antibodies and on the demonstration of duodenal villous atrophy. Treatment necessitates a strict gluten-free diet, which resolves symptoms and enables histological recovery. However, regular follow-up is necessary to assess mucosal healing, which emerges as an important prognostic factor. Recent work on CeD pathogenesis has highlighted how the cross-talk between gluten-specific CD4 + T cells and interleukin-15 can activate cytotoxic intraepithelial lymphocytes and trigger epithelial lesions. Moreover, acquisition by a subset of intraepithelial lymphocytes of somatic gain-of-function mutations in the JAK-STAT pathway was shown to be a decisive step in the progression toward lymphomas complicating CeD, thus opening new therapeutic perspectives for these rare but life-threatening complications.

Novel Nondietary Therapies for Celiac Disease

Celiac Disease (CeD) is defined as a chronic small intestinal immune-mediated enteropathy that is precipitated by exposure to dietary gluten in genetically predisposed individuals. CeD is one of the most common autoimmune disorders affecting around 1% of the population worldwide. Currently, the only acceptable treatment for CeD is strict, lifelong adherence to a gluten-free diet (GFD) which can often present a challenging task. A GFD alone is not sufficient to control symptoms and prevent mucosal damage that can result from unintentional gluten exposure. Moreover, long-term complications can occur in many patients. Consequently, there is an unmet need for non-dietary therapies for the management of CeD. Such therapies could serve as an adjunct to the GFD but eventually may replace it. This review will focus on and discuss non-dietary therapies currently in clinical development for the management of CeD. METHODOLOGY: We searched clinicaltrials.gov and PubMed to extract articles about celiac disease. We used keywords including, but not limited to, "celiac disease," "non-dietary," "therapeutics," "pathophysiology," "Endopeptidases," "tight junction modulators," "vaccine," and "Nexvax2". We focused mainly on articles that conducted pathophysiologic and therapeutic research in human trials.

Evolving Therapy for Celiac Disease

Gluten is known to be the main triggering factor for celiac disease (CeD), an immune-mediated disorder. CeD is therefore managed using a strict and lifelong gluten-free diet (GFD), the only effective treatment available currently. However, the GFD is restrictive. Hence, efforts are being made to explore alternative therapies. Based on their mechanisms of action on various molecular targets involved in the pathogenesis of CeD, these therapies may be classified into one of the following five broad approaches. The first approach focuses on decreasing the immunogenic content of gluten, using strategies like genetically modified wheat, intra-intestinal gluten digestion using glutenases, microwave thermal treatment of hydrated wheat kernels, and gluten pretreatment with either bacterial/ fungal derived endopeptidases or microbial transglutaminase. The second approach involves sequestering gluten in the gut lumen before it is digested into immunogenic peptides and absorbed, using binder drugs like polymer p(HEMA-co-SS), single chain fragment variable (scFv), and anti- gluten antibody AGY. The third approach aims to prevent uptake of digested gluten through intestinal epithelial tight junctions, using a zonulin antagonist. The fourth approach involves tissue transglutaminase (tTG) inhibitors to prevent the enhancement of immunogenicity of digested gluten by the intestinal tTG enzyme. The fifth approach seeks to prevent downstream immune activation after uptake of gluten immunogenic peptides through the intestinal mucosal epithelial layer. Examples include HLA-DQ2 blockers that prevent presentation of gluten derived- antigens by dendritic cells to T cells, immune- tolerizing therapies like the vaccine Nexvax2 and TIMP-Glia, cathepsin inhibitors, immunosuppressants like corticosteroids, azathioprine etc., and anti-cytokine agents targeting TNF-α and interleukin-15. Apart from these approaches, research is being done to evaluate the effectiveness of probiotics/prebiotics, helminth therapy using Necator americanus, low FODMAP diet, and pancreatic enzyme supplementation in CeD symptom control; however, the mechanisms by which they play a beneficial role in CeD are yet to be clearly established. Overall, although many therapies being explored are still in the pre-clinical phase, some like the zonulin antagonist, immune tolerizing therapies and glutenases have reached phase II/III clinical trials. While these potential options appear exciting, currently they may at best be used to supplement rather than supplant the GFD.

Role of Dietary Gluten in Development of Celiac Disease and Type I Diabetes: Management Beyond Gluten-Free Diet

Gluten triggers Celiac Disease (CD) and type I diabetes in genetically predisposed population of human leukocyte antigen DQ2/DQ8+ and associates with disorders such as schizophrenia and autism. Application of a strict gluten-free diet is the only well-established treatment for patients with CD, whereas the treatment for patients with celiac type I diabetes may be depend on the timing and frequency of the diet. The application of a gluten-free diet in patients with CD may contribute to the development of metabolic syndrome and nonalcoholic fatty liver disease and may also lead to a high glycemic index, low fiber diet and micronutrient deficiencies. The alteration of copper bioavailability (deficient, excess or aberrant coordination) may contribute to the onset and progress of related pathologies. Therefore, nutrient intake of patients on a gluten-free diet should be the focus of future researches. Other gluten-based therapies have been rising with interest such as enzymatic pretreatment of gluten, oral enzyme supplements to digest dietary gluten, gluten removal by breeding wheat varieties with reduced or deleted gluten toxicity, the development of polymeric binders to suppress gluten induced pathology.

Development of Decreased-Gluten Wheat Enabled by Determination of the Genetic Basis of lys3a Barley

Celiac disease is the most common food-induced enteropathy in humans, with a prevalence of approximately 1% worldwide. It is induced by digestion-resistant, proline- and glutamine-rich seed storage proteins, collectively referred to as gluten, found in wheat (Triticum aestivum). Related prolamins are present in barley (Hordeum vulgare) and rye (Secale cereale). The incidence of both celiac disease and a related condition called nonceliac gluten sensitivity is increasing. This has prompted efforts to identify methods of lowering gluten in wheat, one of the most important cereal crops. Here, we used bulked segregant RNA sequencing and map-based cloning to identify the genetic lesion underlying a recessive, low-prolamin mutation (lys3a) in diploid barley. We confirmed the mutant identity by complementing the lys3a mutant with a transgenic copy of the wild-type barley gene and then used targeting-induced local lesions in genomes to identify induced single-nucleotide polymorphisms in the three homeologs of the corresponding wheat gene. Combining inactivating mutations in the three subgenomes of hexaploid bread wheat in a single wheat line lowered gliadin and low-molecular-weight glutenin accumulation by 50% to 60% and increased free and protein-bound lysine by 33%.

Coeliac disease

Coeliac disease is an immune-mediated enteropathy against dietary gluten present in wheat, rye and barley and is one of the most common lifelong food-related disorders worldwide. Coeliac disease is also considered to be a systemic disorder characterized by a variable combination of gluten-related signs and symptoms and disease-specific antibodies in addition to enteropathy. The ingestion of gluten leads to the generation of harmful gluten peptides, which, in predisposed individuals, can induce adaptive and innate immune responses. The clinical presentation is extremely variable; patients may have severe gastrointestinal symptoms and malabsorption, extraintestinal symptoms or have no symptoms at all. Owing to the multifaceted clinical presentation, diagnosis remains a challenge and coeliac disease is heavily underdiagnosed. The diagnosis of coeliac disease is achieved by combining coeliac disease serology and small intestinal mucosal histology during a gluten-containing diet. Currently, the only effective treatment for coeliac disease is a lifelong strict gluten-free diet; however, the diet is restrictive and gluten is difficult to avoid. Optimizing diagnosis and care in coeliac disease requires continuous research and education of both patients and health-care professionals.