Editorial: a non-dietary treatment for coeliac disease-two steps forward, one step back? Authors' reply

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.

Emergence of an adaptive immune paradigm to explain celiac disease: a perspective on new evidence and implications for future interventions and diagnosis

INTRODUCTION

Recent patient studies have shown that gluten-free diet is less effective in treating celiac disease than previously believed, and additionally patients remain vulnerable to gluten-induced acute symptoms and systemic cytokine release. Safe and effective pharmacological adjuncts to gluten-free diet are in preclinical and clinical development. Clear understanding of the pathogenesis of celiac disease is critical for drug target identification, establishing efficacy endpoints and to develop non-invasive biomarkers suitable to monitor and potentially diagnose celiac disease.

AREAS COVERED

The role and clinical effects of CD4+ T cells directed against deamidated gluten in the context of an "adaptive immune paradigm" are reviewed. Alternative hypotheses of gluten toxicity are discussed and contrasted. In the context of recent patient studies, implications of the adaptive immune paradigm for future strategies to prevent, diagnose, and treat celiac disease are outlined.

EXPERT OPINION

Effective therapeutics for celiac disease are likely to be approved and necessitate a variety of new clinical instruments and tests to stratify patient need, monitor remission, and confirm diagnosis in uncertain cases. Sensitive assessments of CD4+ T cells specific for deamidated gluten are likely to play a central role in clinical management, and to facilitate research and pharmaceutical development.

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.

The use of peripheral blood mononuclear cells in celiac disease diagnosis and treatment

Introduction: Celiac disease is characterized by an abnormal immune activation driven by the ingestion of gluten from wheat, barley, and rye. Gluten-specific CD4⁺ T cells play an important role in disease pathogenesis and are detectable among peripheral blood mononuclear cells (PBMCs). Areas covered: This review summarizes the use of celiac disease patient PBMCs in clinical applications focusing on their exploitation in the development of diagnostic approaches and novel drugs to replace or complement gluten-free diet. Expert opinion: The most used PBMC-based methods applied in celiac disease research include ELISpot and HLA-DQ:gluten tetramer technology. ELISpot has been utilized particularly in research aiming to develop a celiac disease vaccine and in studies addressing the toxicity of different grains in celiac disease. HLA-DQ:gluten tetramer technology on the other hand initially focused on improving current diagnostics but in combination with additional markers it is also a useful outcome measure in clinical trials to monitor the efficacy of drug candidates. In addition, the technology serves well in the more detailed characterization of celiac disease-specific T cells, thereby possibly revealing novel therapeutic targets. Future studies may also reveal clinical applications for PBMC microRNAs and/or dendritic cells or monocytes present among PBMCs.

Innate and adaptive immunity in celiac disease

PURPOSE OF REVIEW

The current review is prompted by recent studies indicating that adaptive immunity could be sufficient to explain rapid onset symptoms as well as many chronic effects of gluten in celiac disease.

RECENT FINDINGS

Gluten re-exposure in treated celiac disease drives a coordinated systemic cytokine release response implicating T-cell activation within 2 h. Instead of direct effects of gluten on innate immunity, long lasting memory CD4+ T cells activated within 2 h of ingesting gluten or injecting purified gluten peptides now appear to be responsible for acute digestive symptoms. In addition, memory B cells and plasma cells specific for gluten and transglutaminase 2, rather than innate immune cells, are the preferred antigen-presenting cells for gluten in the gut. A variety of innate immune stimuli such as transient infections and local intestinal microbiome, not necessarily gluten itself, may contribute to disease initiation and transition to overt intestinal mucosal injury. Gluten-specific adaptive immunity in the gut and blood are now shown to be closely linked, and systemic cytokine release after gluten provides an additional explanation for extraintestinal manifestations of celiac disease.

SUMMARY

Clinical studies utilizing cytokines as new biomarkers for gluten immunity promise to improve understanding of clinical effects of gluten, accelerate therapeutics development, and augment diagnosis.