Human leukocyte antigen genetics and clinical features of self-treated patients on a gluten-free diet

BACKGROUND AND AIMS

Increasingly, people start a gluten-free diet (GFD) without a clear celiac disease (CD) diagnosis. Human leukocyte antigen (HLA) genotyping is useful in ruling out CD in patients with equivocal results of serologic testing or small-bowel biopsy (SBB), but its utility and the clinical features of patients on self-treated GFD (ST-GFD) are largely unknown.

METHODS

Retrospective study of single tertiary care center cohort compared 137 patients on ST-GFD and 443 patients with well-defined CD. We compared HLA genotype, symptoms, serologic and SBB results, and response to GFD between the 2 groups. Analysis used univariate logistic regression modeling, adjusted for age and sex.

RESULTS

Patients with ST-GFD presented more often with diarrhea (P<0.001), abdominal distention (P<0.001), flatulence (P=0.002), cramping (P=0.02), itchy skin (P=0.02), oral inflammation (P=0.04), and constipation (P=0.01) and less often with anemia (P<0.001) or malaise (P=0.02) than CD patients. In addition, 41% did not carry DQ2.5 and DQ8 versus 6% of CD patients (P<0.001). Only 2% of ST-GFD patients had SBB clearly consistent with CD. Family history of CD showed no difference between groups (P=0.77). Although CD patients had a statistically higher rate of GFD benefit, both groups had a high responsiveness rate (98% vs. 94%; P=0.03).

CONCLUSIONS

HLA genotyping is useful in evaluating patients on an ST-GFD. Although confirmed CD is rare in self-treated patients, most still report benefit from GFD regardless of DQ2 and DQ8 status. Nonceliac gluten sensitivity may play a role.

The Oslo definitions for coeliac disease and related terms

OBJECTIVE

The literature suggests a lack of consensus on the use of terms related to coeliac disease (CD) and gluten.

DESIGN

A multidisciplinary task force of 16 physicians from seven countries used the electronic database PubMed to review the literature for CD-related terms up to January 2011. Teams of physicians then suggested a definition for each term, followed by feedback of these definitions through a web survey on definitions, discussions during a meeting in Oslo and phone conferences. In addition to 'CD', the following descriptors of CD were evaluated (in alphabetical order): asymptomatic, atypical, classical, latent, non-classical, overt, paediatric classical, potential, refractory, silent, subclinical, symptomatic, typical, CD serology, CD autoimmunity, genetically at risk of CD, dermatitis herpetiformis, gluten, gluten ataxia, gluten intolerance, gluten sensitivity and gliadin-specific antibodies.

RESULTS

CD was defined as 'a chronic small intestinal immune-mediated enteropathy precipitated by exposure to dietary gluten in genetically predisposed individuals'. Classical CD was defined as 'CD presenting with signs and symptoms of malabsorption. Diarrhoea, steatorrhoea, weight loss or growth failure is required.' 'Gluten-related disorders' is the suggested umbrella term for all diseases triggered by gluten and the term gluten intolerance should not to be used. Other definitions are presented in the paper.

CONCLUSION

This paper presents the Oslo definitions for CD-related terms.

Tissue-infiltrating lymphocytes analysis reveals large modifications of the duodenal "immunological niche" in coeliac disease after gluten-free diet

OBJECTIVES

The role of T lymphocytes in the pathogenesis of Celiac disease (CD) is well established. However, the mechanisms of T-cell involvement remain elusive. Little is known on the distribution of T subpopulations: T-regulatory (Treg), Th17, CD103, and CD62L cells at disease onset and after gluten-free diet (GFD). We investigated the involvement of several T subpopulations in the pathogenesis of CD.

METHODS

We studied T cells both in the peripheral blood (PB) and the tissue-infiltrating lymphocytes (TILs) from the mucosa of 14 CD patients at presentation and after a GFD, vs. 12 controls.

RESULTS

Our results extend the involvement of Treg, Th1, and Th17 cells in active CD inflammation both in the PB and at the TILs. At baseline, Tregs, Th1, and Th17 cells are significantly higher in active CD patients in TILs and PB. They decreased after diet. Moreover, CD62L+ TILs were increased at diagnosis as compared with GFD patients.

CONCLUSIONS

Our data show significant modifications of the above-mentioned subpopulations both in the PB and TILs. The increase of suppressive Tregs in active CD both in the PB and TILs is intriguing. T lymphocytes are known to have a crucial role in the pathogenesis of CD. We have shown that gluten trigger results in systemic recruitment of T lymphocytes, the unbalance between pro-inflammatory and anti-inflammatory populations and the increase of CD62L+ T cells in TILs. Our results delineate a more complete picture of T-cell subsets in active vs. GFD disease. Our data of T-cell subpopulations, combined with known data on cytokine production, support the concept that duodenal micro-environment acts as an immunological niche and this recognition may have an important role in the diagnosis, prognosis and therapeutical approach of CD.

Celiac disease: a challenging disease for pharmaceutical scientists

Celiac disease (CD) is an immune-mediated enteropathy triggered by the ingestion of gluten-containing grains that affects ~1% of the white ethnic population. In the last decades, a rise in prevalence of CD has been observed that cannot be fully explained by improved diagnostics. Genetic predisposition greatly influences the susceptibility of individuals towards CD, though environmental factors also play a role. With no pharmacological treatments available, the only option to keep CD in remission is a strict and permanent exclusion of dietary gluten. Such a gluten-free diet is difficult to maintain because of gluten's omnipresence in food (e.g., additive in processed food). The development of adjuvant therapies which would permit the intake of small amounts of gluten would be desirable to improve the quality of life of patients on a gluten-free diet. Such therapies include gluten-degrading enzymes, polymeric binders, desensitizing vaccines, anti-inflammatory drugs, transglutaminase 2 inhibitors, and HLA-DQ2 blockers. However, many of these approaches pose pharmaceutical challenges with respect to drug formulation and stability, or application route and dosing interval. This perspective article discusses how pharmaceutical scientists may deal with these challenges and contribute to the implementation of novel therapeutic options for patients with CD.

Association of HLA-DQ gene with bowel transit, barrier function, and inflammation in irritable bowel syndrome with diarrhea

Patients with irritable bowel syndrome (IBS) with diarrhea (IBS-D) carrying human leukocyte antigen (HLA)-DQ2/8 genotypes benefit from gluten withdrawal. Our objective was to compare gastrointestinal barrier function, mucosal inflammation, and transit in nonceliac IBS-D patients and assess association with HLA-DQ2/8 status. In 45 IBS-D patients who were naive to prior exclusion of dietary gluten, we measured small bowel (SB) and colonic mucosal permeability by cumulative urinary lactulose and mannitol excretion (0-2 h for SB and 8-24 h for colon), inflammation on duodenal and rectosigmoid mucosal biopsies (obtained in 28 of 45 patients), tight junction (TJ) protein mRNA and protein expression in SB and rectosigmoid mucosa, and gastrointestinal and colonic transit by validated scintigraphy. SB mucosal biopsies were stained with hematoxylin-eosin to assess villi and intraepithelial lymphocytes, and immunohistochemistry was used to assess CD3, CD8, tryptase, and zonula occludens 1 (ZO-1); colonic biopsy intraepithelial lymphocytes were quantitated. Associations of HLA-DQ were assessed using Wilcoxon's rank-sum test. Relative to healthy control data, we observed a significant increase in SB permeability (P < 0.001), a borderline increase in colonic permeability (P = 0.10), and a decrease in TJ mRNA expression in rectosigmoid mucosa in IBS-D. In HLA-DQ2/8-positive patients, ZO-1 protein expression in the rectosigmoid mucosa was reduced compared with that in HLA-DQ2/8-negative patients and colonic transit was slower than in HLA-DQ2/8-negative patients. No other associations with HLA genotype were identified. There is abnormal barrier function (increased SB permeability and reduced mRNA expression of TJ proteins) in IBS-D relative to health that may be, in part, related to immunogenotype, given reduced ZO-1 protein expression in rectosigmoid mucosa in HLA-DQ2/8-positive relative to HLA-DQ2/8-negative patients.

Non-celiac wheat sensitivity: separating the wheat from the chat!

Historically, it has been reported that patients with undetected celiac disease (CD) may present with irritable bowel syndrome (IBS) type symptoms. This has led to the recommendation by the American College of Gastroenterology Task force that patients presenting with diarrhea predominant IBS type symptoms should be serologically tested for CD. Concurrently speculative media data suggest that the US general public have increased their uptake of a gluten-free diet (GFD) far in excess of the known prevalence of CD. This may suggest that individuals with gastrointestinal symptoms are deriving benefit from a GFD even if they do not have CD. This has led to the scientific community considering the evidence for an emerging concept of non-celiac wheat sensitivity. There is a significant disparity in our views about what this phenomenon may be. There is also confusion about the nomenclature for this entity and indeed whether patients are suffering due to symptoms related to gluten or perhaps other components of wheat, for example fructans. In this month's edition of the American Journal of Gastroenterology, we see evidence to support the clinical concept of wheat sensitivity or intolerance. Irrespective of the nomenclature Carroccio provides a clinically applicable approach that may be adopted internationally by clinicians. This offers a new option in our armamentarium when seeing patients with IBS type symptoms.

Anti-gluten immune response following Toxoplasma gondii infection in mice

Gluten sensitivity may affect disease pathogenesis in a subset of individuals who have schizophrenia, bipolar disorder or autism. Exposure to Toxoplasma gondii is a known risk factor for the development of schizophrenia, presumably through a direct pathological effect of the parasite on brain and behavior. A co-association of antibodies to wheat gluten and to T. gondii in individuals with schizophrenia was recently uncovered, suggesting a coordinated gastrointestinal means by which T. gondii and dietary gluten might generate an immune response. Here, we evaluated the connection between these infectious- and food-based antigens in mouse models. BALB/c mice receiving a standard wheat-based rodent chow were infected with T. gondii via intraperitoneal, peroral and prenatal exposure methods. Significant increases in the levels of anti-gluten IgG were documented in all infected mice and in offspring from chronically infected dams compared to uninfected controls (repetitive measures ANOVAs, two-tailed t-tests, all p≤0.00001). Activation of the complement system accompanied this immune response (p≤0.002–0.00001). Perorally-infected females showed higher levels of anti-gluten IgG than males (p≤0.009) indicating that T. gondii-generated gastrointestinal infection led to a significant anti-gluten immune response in a sex-dependent manner. These findings support a gastrointestinal basis by which two risk factors for schizophrenia, T. gondii infection and sensitivity to dietary gluten, might be connected to produce the immune activation that is becoming an increasingly recognized pathology of psychiatric disorders.

Interleukin 15 provides relief to CTLs from regulatory T cell-mediated inhibition: implications for adoptive T cell-based therapies for lymphoma

PURPOSE

Systemic administration of recombinant interleukin (IL)-2 is used to support the expansion and persistence of adoptively transferred antigen-specific CTLs in patients with cancer. However, IL-2 also expands regulatory T cells (Treg) that in turn impair the antitumor activity of CTLs. As recombinant IL-15 is approaching clinical applications, we assessed the effects of this cytokine on the proliferation and antitumor activity of CTLs in the presence of Tregs. We used the model of adoptive transfer of Epstein-Barr virus (EBV)-CTLs, as these cells induce responses in patients with EBV-associated Hodgkin lymphoma, and Tregs are frequently abundant in these patients.

EXPERIMENTAL DESIGN

Tregs were isolated from the peripheral blood of healthy donors and patients with Hodgkin lymphoma or from Hodgkin lymphoma tumors and assessed for their ability to inhibit the proliferation and antitumor activity of EBV-CTLs in the presence of IL-15 or IL-2. Specific molecular pathways activated by IL-15 were also explored.

RESULTS

We found that in the presence of Tregs, IL-15, but not IL-2, promoted the proliferation, effector function, and resistance to apoptosis of effectors T cells and EBV-CTLs. IL-15 did not reverse or block Tregs but instead preferentially supported the proliferation of CTLs and effector T cells as compared with Tregs.

CONCLUSIONS

IL-15 selectively favors the survival, proliferation, and effector function of antigen-specific CTLs in the presence of Tregs, and thus IL-15, unlike IL-2, would have a significant impact in sustaining expansion and persistence of adoptively transferred CTLs in patients with cancer, including those infused with EBV-CTLs for treatment of EBV-associated malignancies.

Changes in intestinal permeability in patients with cholecystolithiasis

AIM: To investigate whether intestinal permeability changes in patients with cholecystolithiasis.

METHODS: Twenty-four patients with cholecystolithiasis and 20 healthy adults were included in the study. Intestinal permeability was assessed using the urine lactulose/mannitol (L/M) ratio measured by high pressure liquid chromatography.

RESULTS: Intestinal permeability was significantly higher in terms of the L/M ratio in the cholecystolithiasis group than in the control group (0.035 ± 0.026 vs 0.020 ± 0.005, P = 0.015). The percentage of subjects who had a L/M ratio exceeding the upper limit of normal (0.022) was significantly higher in the cholecystolithiasis group than in the control group (66.7% vs 15%, P = 0.001).

CONCLUSION: Intestinal permeability changes in patients with cholecystolithiasis.

The irritable bowel syndrome-celiac disease connection

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder that has a significant impact on quality of life and health care resources. Celiac disease (CD), a gluten-sensitive enteropathy, can be mistaken for IBS. This article discusses the connection between IBS and CD and the new concept of nonceliac gluten sensitivity (NCGS). NCGS may occur in the presence of a normal or near-normal small bowel biopsy. Some patients with IBS without CD may derive symptomatic benefit from a gluten-free diet. Future research could facilitate a significant impact on the quality of life in this potential subgroup of patients.

Non-celiac gluten sensitivity

Gluten sensitivity has been best recognized and understood in the context of two conditions, celiac disease and wheat allergy. However, some individuals complain of symptoms in response to ingestion of "gluten," without histologic or serologic evidence of celiac disease or wheat allergy. The term non-celiac gluten sensitivity (NCGS) has been suggested for this condition, although a role for gluten proteins as the sole trigger of the associated symptoms remains to be established. This article reviews the available information regarding symptomatology, epidemiology and genetics, serology and histology, and in vitro and in vivo experimental data on the pathophysiology of NCGS.

[Gluten-related disorders and demyelinating diseases]

Gluten-related disorders are a spectrum of systemic immune mediated conditions that occur at any age in genetically susceptible individuals upon ingesting gluten. Celiac disease and gluten sensitivity are the most important conditions of the spectrum. They may be associated with other autoimmune diseases, such as multiple sclerosis and neuromyelitis optica. Treatment with a gluten-free diet can provide considerable benefits to the patients having both a gluten-related disorder and one of these 2 demyelinating diseases of the central nervous system.

Gut microbiota, immune development and function

The microbiota of Westerners is significantly reduced in comparison to rural individuals living a similar lifestyle to our Paleolithic forefathers but also to that of other free-living primates such as the chimpanzee. The great majority of ingredients in the industrially produced foods consumed in the West are absorbed in the upper part of small intestine and thus of limited benefit to the microbiota. Lack of proper nutrition for microbiota is a major factor under-pinning dysfunctional microbiota, dysbiosis, chronically elevated inflammation, and the production and leakage of endotoxins through the various tissue barriers. Furthermore, the over-comsumption of insulinogenic foods and proteotoxins, such as advanced glycation and lipoxidation molecules, gluten and zein, and a reduced intake of fruit and vegetables, are key factors behind the commonly observed elevated inflammation and the endemic of obesity and chronic diseases, factors which are also likely to be detrimental to microbiota. As a consequence of this lifestyle and the associated eating habits, most barriers, including the gut, the airways, the skin, the oral cavity, the vagina, the placenta, the blood-brain barrier, etc., are increasingly permeable. Attempts to recondition these barriers through the use of so called 'probiotics', normally applied to the gut, are rarely successful, and sometimes fail, as they are usually applied as adjunctive treatments, e.g. in parallel with heavy pharmaceutical treatment, not rarely consisting in antibiotics and chemotherapy. It is increasingly observed that the majority of pharmaceutical drugs, even those believed to have minimal adverse effects, such as proton pump inhibitors and anti-hypertensives, in fact adversely affect immune development and functions and are most likely also deleterious to microbiota. Equally, it appears that probiotic treatment is not compatible with pharmacological treatments. Eco-biological treatments, with plant-derived substances, or phytochemicals, e.g. curcumin and resveratrol, and pre-, pro- and syn-biotics offers similar effects as use of biologicals, although milder but also free from adverse effects. Such treatments should be tried as alternative therapies; mainly, to begin with, for disease prevention but also in early cases of chronic diseases. Pharmaceutical treatment has, thus far, failed to inhibit the tsunami of endemic diseases spreading around the world, and no new tools are in sight. Dramatic alterations, in direction of a paleolithic-like lifestyle and food habits, seem to be the only alternatives with the potential to control the present escalating crisis. The present review focuses on human studies, especially those of clinical relevance.

Celiac disease: an immunological jigsaw

Celiac disease (CD) is a chronic enteropathy induced by dietary gluten in genetically predisposed people. The keystone of CD pathogenesis is an adaptive immune response orchestrated by the interplay between gluten and MHC class II HLA-DQ2 and DQ8 molecules. Yet, other factors that impair immunoregulatory mechanisms and/or activate the large population of intestinal intraepithelial lymphocytes (IEL) are indispensable for driving tissue damage. Herein, we summarize our current understanding of the mechanisms and consequences of the undesirable immune response initiated by gluten peptides. We show that CD is a model disease to decipher the role of MHC class II molecules in human immunopathology, to analyze the mechanisms that link tolerance to food proteins and autoimmunity, and to investigate how chronic activation of IEL can lead to T cell lymphomagenesis.

Emerging concepts: from coeliac disease to non-coeliac gluten sensitivity

The rise in gluten consumption over time has led to the increasing recognition of coeliac disease (CD) with associated complications. However, only recently has there been an appreciation that the spectrum of gluten-related disorders is greater than just CD, which may explain the growing global popularity in gluten-free products. Current literature suggests that a newly recognised clinical entity in the form of non-coeliac gluten sensitivity (NCGS) may be the most common gluten-related disorder encountered by healthcare professionals, although its exact prevalence is as yet unknown. This article will review the historical relationship between mankind and gluten as well as the progressive recognition that it is possible for gluten to have a deleterious effect on our health. To this effect we discuss the prevalence, diagnosis and complications of CD including the benefits derived from a gluten-free diet (GFD). Finally, we discuss our current understanding of NCGS, in addition to highlighting the need for further research to determine the extent, clinicopathological features and serological biomarkers to help recognise this emerging condition in clinical practice.

Serological tests in gluten sensitivity (nonceliac gluten intolerance)

GOALS

To characterize the serological pattern of gluten sensitivity (GS) and to compare it with that found in celiac disease.

BACKGROUND

GS has recently been identified as a new clinical entity included in the spectrum of gluten-related disorders, but it is still lacking of diagnostic markers.

STUDY

Sera from 78 patients with GS and 80 patients with celiac disease were retrospectively assessed for immunoglobulin (Ig)G/IgA antigliadin antibodies (AGA), IgG deamidated gliadin peptide antibodies (DGP-AGA), IgA tissue transglutaminase antibodies (tTGA), and IgA endomysial antibodies (EmA).

RESULTS

IgG AGA were positive in 56.4% of GS patients and in 81.2% of celiac patients, with high antibody titers in both groups. IgA AGA were detected in 7.7% of GS patients and in 75% of celiac patients, showing lower enzyme-linked immunosorbent assay activities in GS than those found in celiac disease. Only 1 of the 78 patients with GS was positive for IgG DGP-AGA (detected in 88.7% of patients with celiac disease). IgA tTGA and IgA EmA were negative in all GS patients, whereas their positivity in celiac patients was 98.7% and 95%, respectively. Patients with GS displayed a variegated clinical picture with intestinal and extraintestinal symptoms (abdominal pain, bloating, diarrhea, constipation, foggy mind, tiredness, eczema/skin rash, headache, joint/muscle pain, numbness of legs/arms, depression, and anemia) together with normal or mildly abnormal small intestinal mucosa.

CONCLUSIONS

The serological pattern of GS is characterized by IgG AGA positivity in more than half of cases associated to IgA AGA in a few patients, but without EmA, tTGA, and DGP-AGA, which are the specific markers of celiac disease.

Predictors of gluten avoidance and implementation of a gluten-free diet in children and adolescents without confirmed celiac disease

OBJECTIVES

To determine independent predictors of gluten avoidance and of a physician's decision to initiate a gluten-free diet (GFD) in children and adolescents without confirmed celiac disease.

STUDY DESIGN

We performed a structured medical record review of 579 patients aged 1-19 years presenting for evaluation of celiac disease between January 2000 and December 2010 at a large Boston teaching hospital. We collected data including demographic information, medical history, serology, small intestinal biopsy, history of gluten avoidance, and the postworkup recommendation of implementation of a GFD. Predictors of gluten-related issues were identified by multivariate logistic regression.

RESULTS

Among 579 children without a previous diagnosis of celiac disease (mean age, 8.7 years), 43 (7.4%) had ever avoided gluten. Independent predictors of gluten avoidance were irritability or poor temper (OR, 3.2), diarrhea (OR, 2.5), weight issues (OR, 0.4), pervasive developmental disorder (OR, 5.3), and family history of celiac disease (OR, 2.2). Among 143 children without confirmed celiac disease who underwent diagnostic evaluation, several predictive factors were associated with a physician- recommended/parent-initiated GFD: irritability (OR, 6.4), diarrhea (OR, 3.4), pervasive developmental disorder (OR, 7.9), and positive serology before the referral (OR, 4.3).

CONCLUSION

Gluten avoidance among children and adolescents without a previous diagnosis of celiac disease is relatively common. The identified predictors suggest that gluten avoidance is associated with nonspecific behavioral and gastrointestinal complaints and perhaps with the perceived dietary responses in another family member thought to have celiac disease.

Are transglutaminase 2 inhibitors able to reduce gliadin-induced toxicity related to celiac disease? A proof-of-concept study

PURPOSE

Celiac disease is an autoimmune-mediated enteropathy characterized by adaptive and innate immune responses to dietary gluten in wheat, rye and barley in genetically susceptible individuals. Gluten-derived gliadin peptides are deamidated by transglutaminase 2 (TG2), leading to an immune response in the small-intestinal mucosa. TG2 inhibitors have therefore been suggested as putative drugs for celiac disease. In this proof-of-concept study we investigated whether two TG2 inhibitors, cell-impermeable R281 and cell-permeable R283, can prevent the toxic effects of gliadin in vitro and ex vivo.

METHODS

Intestinal epithelial Caco-2 cells were treated with peptic-tryptic-digested gliadin (PT-gliadin) with or without TG2 inhibitors and thereafter direct toxic effects (transepithelial resistance, cytoskeletal rearrangement, junction protein expression and phoshorylation of extracellular-signal-regulated kinase 1/2) were determined. In an organ culture of celiac-patient-derived small-intestinal biopsies we measured secretion of TG2-autoantibodies into the culture medium and the densities of CD25- and interleukin (IL) 15-positive cells, forkhead box P3 (FOXP3)-positive regulatory T cells (Tregs) and Ki-67-positive proliferating crypt cells.

RESULTS

Both TG2 inhibitors evinced protective effects against gliadin-induced detrimental effects in Caco-2 cells but the cell-impermeable R281 seemed slightly more potent. In addition, TG2 inhibitor R281 modified the gluten-induced increase in CD25- and IL15-positive cells, Tregs and crypt cell proliferation, but had no effect on antibody secretion in celiac-patient-derived biopsies.

CONCLUSIONS

Our results suggest that TG2 inhibitors are able to reduce certain gliadin-induced effects related to responses in vitro and ex vivo.

Animal models to study gluten sensitivity

The initial development and maintenance of tolerance to dietary antigens is a complex process that, when prevented or interrupted, can lead to human disease. Understanding the mechanisms by which tolerance to specific dietary antigens is attained and maintained is crucial to our understanding of the pathogenesis of diseases related to intolerance of specific dietary antigens. Two diseases that are the result of intolerance to a dietary antigen are celiac disease (CD) and dermatitis herpetiformis (DH). Both of these diseases are dependent upon the ingestion of gluten (the protein fraction of wheat, rye, and barley) and manifest in the gastrointestinal tract and skin, respectively. These gluten-sensitive diseases are two examples of how devastating abnormal immune responses to a ubiquitous food can be. The well-recognized risk genotype for both is conferred by either of the HLA class II molecules DQ2 or DQ8. However, only a minority of individuals who carry these molecules will develop either disease. Also of interest is that the age at diagnosis can range from infancy to 70-80 years of age. This would indicate that intolerance to gluten may potentially be the result of two different phenomena. The first would be that, for various reasons, tolerance to gluten never developed in certain individuals, but that for other individuals, prior tolerance to gluten was lost at some point after childhood. Of recent interest is the concept of non-celiac gluten sensitivity, which manifests as chronic digestive or neurologic symptoms due to gluten, but through mechanisms that remain to be elucidated. This review will address how animal models of gluten-sensitive disorders have substantially contributed to a better understanding of how gluten intolerance can arise and cause disease.

Absence of somatization in non-coeliac gluten sensitivity

OBJECTIVE

In contrast to coeliac disease (CD), the mechanism behind non-coeliac gluten sensitivity (NCGS) is unclear. The aims of the study were to measure the presence of somatization, personality traits, anxiety, depression, and health-related quality of life in NCGS individuals compared with CD patients and healthy controls, and to compare the response to gluten challenge between NCGS and CD patients.

MATERIAL AND METHODS

We examined 22 CD patients and 31 HLA-DQ2+ NCGS patients without CD, all on a gluten-free diet. All but five CD patients were challenged orally for 3 days with gluten; symptom registration was performed during challenge. A comparison group of 40 healthy controls was included. Patients and healthy controls completed questionnaires regarding anxiety, depression, neuroticism and lie, hostility and aggression, alexithymia and health locus of control, physical complaints, and health-related quality of life.

RESULTS

The NCGS patients reported more abdominal (p = 0.01) and non-abdominal (p < 0.01) symptoms after gluten challenge than CD patients. There were no significant differences between CD and NCGS patients regarding personality traits, level of somatization, quality of life, anxiety, and depressive symptoms. The somatization level was low in CD and NCGS groups. Symptom increase after gluten challenge was not related to personality in NCGS patients.

CONCLUSIONS

NCGS patients did not exhibit a tendency for general somatization. Personality and quality of life did not differ between NCGS and CD patients, and were mostly at the same level as in healthy controls. NCGS patients reported more symptoms than CD patients after gluten challenge.

Intraepithelial lymphocytes in celiac disease immunopathology

Celiac disease is a T cell-mediated immune disorder induced by dietary gluten that is characterized by the development of an inflammatory anti-gluten CD4 T cell response, anti-gluten antibodies, and autoantibodies against tissue transglutaminase 2 and the activation of intraepithelial lymphocytes (IELs) leading to the destruction of the intestinal epithelium. Intraepithelial lymphocytes represent a heterogeneous population of T cells composed mainly of cytotoxic CD8 T cells residing within the epithelial layer, whose main role is to maintain the integrity of the epithelium by eliminating infected cells and promoting epithelial repair. Dysregulated activation of IELs is a hallmark of CD and is critically involved in epithelial cell destruction and the subsequent development of villous atrophy. In this review, we compare and contrast the phenotype and function of human and mouse small intestinal IELs under physiological conditions. Furthermore, we discuss how conditions of epithelial distress associated with overexpression of IL-15 and non-classical MHC class I molecules induce cytotoxic IELs to become licensed killer cells that upregulate activating NKG2D and CD94/NKG2C natural killer receptors, acquiring lymphokine killer activity. Pathways leading to dysregulated IEL activation could eventually be targeted to prevent villous atrophy and treat patients who respond poorly to gluten-free diet.

Expression of microbiota, Toll-like receptors, and their regulators in the small intestinal mucosa in celiac disease

OBJECTIVES

Less than one-tenth of the carriers of the risk genes HLA-DQ2 or HLA-DQ8 develop celiac disease, suggesting that other genetic and environmental factors are important in the pathogenesis. The role of gut microbiota has been addressed previously with inconsistent findings. Our aim was to evaluate microbiota, its receptors (Toll-like receptors [TLRs]), and regulators of the TLRs in the small intestinal mucosa in celiac disease.

METHODS

Microbiota was analyzed by quantitative polymerase chain reaction (total bacteria and 10 bacterial group- and species-specific primers) and gene expression of interleukin-8 (IL-8), TLR2, TLR3, TLR4, TLR5, TLR9, and regulators of TLRs, Toll-interacting protein (TOLLIP), and single immunoglobulin IL-1R-related molecule, by relative quantitative reverse transcription-polymerase chain reaction in 10 children with celiac disease (untreated celiacs), 9 children with normal small intestinal mucosa (controls), and 6 adults with celiac disease with normal small intestinal mucosa after following a gluten-free diet (treated celiacs).

RESULTS

Small intestinal microbiota was comparable among controls, untreated celiacs, and treated celiacs. Expression of IL-8 mRNA, a marker of intestinal inflammation, was significantly increased in untreated celiacs as compared with treated celiacs (P=0.002) and controls (P=0.001). Expression of TLR-2 mRNA was significantly decreased in untreated (P=0.001) and treated (P=0.03) celiacs, whereas expression of TLR-9 mRNA was increased in untreated celiacs (P=0.001) as compared with controls. Expression of TOLLIP mRNA was downregulated in untreated celiacs as compared with controls (P=0.02).

CONCLUSIONS

Altered gene expression of TLR2, TLR9, and TOLLIP in small intestinal biopsies in celiac disease suggests that microbiota-associated factors may be important in the development of the disease.

Impaired control of effector T cells by regulatory T cells: a clue to loss of oral tolerance and autoimmunity in celiac disease?

OBJECTIVES

Regulatory T cells (Tregs) are instrumental for tolerance to self-antigens and dietary proteins. We have previously shown that interleukin (IL)-15, a cytokine overexpressed in the intestine of patients with celiac disease (CD), does not impair the generation of functional Tregs but renders human T cells resistant to Treg suppression. Treg numbers and responses of intestinal and peripheral T lymphocytes to suppression by Tregs were therefore compared in CD patients and controls.

METHODS

Intraepithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs) were isolated from duodenal biopsy specimens of CD patients and controls. Concomitantly, CD4+CD25+ T lymphocytes (Tregs) were purified from blood. Responses of IELs and of LPLs, and peripheral lymphocytes (PBLs) to suppression by Tregs were tested by analyzing anti-CD3-induced proliferation and interferon (IFN)-γ production in the presence or absence of peripheral Tregs. Lamina propria and peripheral CD4+CD25+FOXP3+ T cells were assessed by flow cytometry.

RESULTS

Although percentages of CD4+CD25+FOXP3+ LPLs were significantly increased in patients with active CD, proliferation and IFN-γ production of intestinal T lymphocytes were significantly less inhibited by autologous or heterologous Tregs in CD patients than in controls (P < 0.01). In all tested CD patients, IEL were unable to respond to Tregs. Resistance of LPLs and PBLs to Treg suppression was observed in patients with villous atrophy who had significantly enhanced serum levels of IL-15 compared with patients without villous atrophy and controls.

CONCLUSIONS

Our results indicate that effector T lymphocytes from active CD become resistant to suppression by Tregs. This resistance might cause loss of tolerance to gluten, but also to self-antigens.

Advances in coeliac disease

PURPOSE OF REVIEW

This article critically summarizes the recent scientific and clinical advances in coeliac disease.

RECENT FINDINGS

Epidemiological studies have shown that coeliac disease is as common in parts of Asia, Africa and Eastern Europe as in the western world. Genome-wide association studies continue to identify genetic susceptibilities that are both unique to coeliac disease and overlap with other autoimmune diseases. Human leukocyte antigen genotyping offers additional sensitivity in detecting coeliac disease in individuals who have self-prescribed gluten-free diets (GFD) or have atypical presentations. Immunological advances have highlighted the potential proinflammatory pitfalls of vitamin A supplementation in active coeliac disease and have enabled identification of oat and barley subsets that may be safely incorporated into coeliac diets. Large population-based studies have expanded our knowledge of the long-term risks of coeliac disease, in addition to excluding infertility as a cause for concern once a GFD has been established.

SUMMARY

The long-term implications of active coeliac disease emphasize the need for early detection and strict adherence to GFD, which remains the cornerstone of management. Technological advances in food modulation and immuno-therapies offer promise, but remain in the translational phases of clinical trials at present.

New understanding of gluten sensitivity

Among gluten-related disorders, gluten sensitivity is an emerging entity that is characterized by a wide array of manifestations. In particular, patients complain of IBS-like symptoms and extraintestinal manifestations that occur shortly after the ingestion of gluten. Symptoms improve or disappear when gluten is withdrawn from the diet, and recur if gluten is reintroduced. Laboratory tests are usually unhelpful for diagnosis, although ~50% of patients are positive for IgG antigliadin antibodies. The natural history of gluten sensitivity is unknown; in particular, it is still to be clarified whether this disorder is permanent or transient and whether it is linked to autoimmunity. The pathogenesis of gluten sensitivity is unclear; data so far demonstrate a predominant activation of innate immune responses. Further research is necessary to establish the main clinicopathological features of gluten sensitivity, thus enabling physicians to improve their management of the increasing number of patients who are sensitive to dietary gluten.

Spectrum of gluten-related disorders: consensus on new nomenclature and classification

A decade ago celiac disease was considered extremely rare outside Europe and, therefore, was almost completely ignored by health care professionals. In only 10 years, key milestones have moved celiac disease from obscurity into the popular spotlight worldwide. Now we are observing another interesting phenomenon that is generating great confusion among health care professionals. The number of individuals embracing a gluten-free diet (GFD) appears much higher than the projected number of celiac disease patients, fueling a global market of gluten-free products approaching $2.5 billion (US) in global sales in 2010. This trend is supported by the notion that, along with celiac disease, other conditions related to the ingestion of gluten have emerged as health care concerns. This review will summarize our current knowledge about the three main forms of gluten reactions: allergic (wheat allergy), autoimmune (celiac disease, dermatitis herpetiformis and gluten ataxia) and possibly immune-mediated (gluten sensitivity), and also outline pathogenic, clinical and epidemiological differences and propose new nomenclature and classifications.

Gluten sensitivity: problems of an emerging condition separate from celiac disease

Gluten sensitivity appears to be emerging as a separate condition from celiac disease, yet no clear definition or diagnosis exists. As a result, patients with gluten sensitivity experience delayed diagnosis and continuing symptoms if they consume gluten. This emerging medical problem may involve human genetics, plant genetic modifications, gluten as a food additive, environmental toxins, hormonal influences, intestinal infections and autoimmune diseases. The treatment is similar to that for celiac disease - a gluten-free diet. The use of a gluten-free diet or an elimination diet is encouraged in assisting people to determine whether or not they are gluten sensitive. It is time to not only recognize, but to treat and further research gluten sensitivity, as unconfirmed environmental factors continue to spread this problem further into the general population.

Differentiating food allergies from food intolerances

Adverse reactions to foods are extremely common, and generally they are attributed to allergy. However, clinical manifestations of various degrees of severity related to ingestion of foods can arise as a result of a number of disorders, only some of which can be defined as allergic, implying an immune mechanism. Recent epidemiological data in North America showed that the prevalence of food allergy in children has increased. The most common food allergens in the United States include egg, milk, peanut, tree nuts, wheat, crustacean shellfish, and soy. This review examines the various forms of food intolerances (immunoglobulin E [IgE] and non-IgE mediated), including celiac disease and gluten sensitivity. Immune mediated reactions can be either IgE mediated or non-IgE mediated. Among the first group, Immediate GI hypersensitivity and oral allergy syndrome are the best described. Often, but not always, IgE-mediated food allergies are entities such as eosinophilic esophagitis and eosinophilic gastroenteropathy. Non IgE-mediated immune mediated food reactions include celiac disease and gluten sensitivity, two increasingly recognized disorders. Finally, non-immune mediated reactions encompass different categories such as disorders of digestion and absorption, inborn errors of metabolism, as well as pharmacological and toxic reactions.

Gluten sensitivity in Meniere's disease

OBJECTIVES/HYPOTHESIS

Wheat is one of the most common food allergens found in patients with Meniere's disease (MD). Gluten from wheat has been identified to have a etiopathogenetic role in celiac disease, IgE hypersensitivity to wheat disease, and recently to gluten sensitivity. The aim of this study was to verify the incidence of gliadin prick test response in patients affected by MD.

STUDY DESIGN

Prospective individual case-control study.

METHODS

There were 58 adult patients with definite MD, 25 healthy volunteers, and 25 patients with grass pollen rhinoconjunctivitis tested with skin prick test to gliadin.

RESULTS

A total of 33 MD patients (56.9%) proved to be sensitive to gliadin, eight of whom were positive to prick test after 20 minutes, 13 after 6 hours, 11 after 12 hours, and one after 24 hours.

CONCLUSIONS

This is the first report of gliadin skin test response in MD. Further studies are needed to define the relationship between immune response to wheat proteins and MD symptoms.

Gluten related disorders

Gluten associated disorders and the question around these associations has recently attracted attentions of many health professionals. This is because of high prevalence of undiagnosed gluten related disorders presenting with a multitude of symptoms and complications inside and outside small bowel. While the environmental factors associated with a complex genetics are leading to destructions of the small intestinal villi resulting in malabsorption syndrome in CD, GS is characterised by negative antibodies and grossly normal histology. The association between celiac disease and other disorders has been clearly established and there have been many reports of numerous intestinal and extra intestinal coexistent disorders with CD. But there is little information available regarding the clinical behavior of gluten sensitivity. In this review we discuss the clinical presentation of non-celiac GS and the prospect of current and the future diagnostic pathway.

Autism spectrum disorder and celiac disease: no evidence for a link

OBJECTIVE: To evaluate the possible association between celiac disease (CD) and/or gluten sensitivity (GS) and autism spectrum disorder (ASD). METHODS: Occurrences of CD were determined in a group of children and adolescents affected by ASD and, conversely, occurrences of ASD were assessed in a group of biopsy-proven celiac patients. To detect the possible existence of GS, the levels of antigliadin antibodies in ASD patients were assessed and compared with the levels in a group of non-celiac children. RESULTS: The prevalence of CD or GS in ASD patients was not greater than in groups originating from the same geographical area. Similarly the prevalence of ASD was not greater than in a group of biopsy-proven CD patients. CONCLUSION: No statistically demonstrable association was found between CD or GS and ASD. Consequently, routine screening for CD or GS in all patients with ASD is, at this moment, neither justified nor cost-effective.

Coeliac Disease in the 21st Century: No Longer "Kids' Stuff"

Background

We aimed to determine if Coeliac disease (CD) can be still be considered a predominantly paediatric disorder, in spite of the increased incidence of adult-onset CD reported in recent years.

Methods

An observational, descriptive, and retrospective study was developed at two Spanish hospitals. Data was collected and analyzed from all paediatric and adult patients newly diagnosed with CD throughout the year 2010. CD diagnoses were based on a concordant clinical history, serology, HLA-DQ compatibility, the presence of mucosal lesions in duodenal biopsies with gluten dependence of symptoms, and histological lesions.

Results

A total of 79 patients were diagnosed with CD throughout 2010, of which 68 (86.1%) were adults. Classic symptoms (diarrhoea and iron-deficiency anaemia) were more frequent in children (90.9%), being present in only 54.4% of adults (p = 0.02). Adult patients showed, mainly, abdominal pain, dyspepsia, and GERD-related symptoms. Villous atrophy (Marsh III) was present in 63.7% of children, but only in 19.1% of adults (p = 0.004). Positive tTGA was present in 81.8% of the children and only in 19.1% of the adults (p = 0.004). Haemoglobin levels were significantly lower in children (p = 0.025), but no differences were observed in iron and ferritin blood levels.

Conclusions

Our study shows that adult-onset CD was the predominant presentation in two hospitals in Spain in the year 2010. Therefore, CD can no longer be considered a predominantly paediatric disorder. Marsh I and negative tTGA titters are characteristic in most of adults. New diagnostic algorithms are needed to improve correct diagnosis of CD in adults.

The prevalence of celiac disease among patients with nonconstipated irritable bowel syndrome is similar to controls

BACKGROUND & AIMS

Guidelines recommend that patients with symptoms of nonconstipated irritable bowel syndrome (NC-IBS) undergo testing for celiac disease (CD). We evaluated the prevalence of CD antibodies, and biopsy confirmed CD among patients with NC-IBS in a large US population.

METHODS

In a study conducted at 4 sites, from 2003 to 2008, we compared data from 492 patients with symptoms of NC-IBS to 458 asymptomatic individuals who underwent colonoscopy examinations for cancer screening or polyp surveillance (controls). All participants provided blood samples for specific and nonspecific CD-associated antibodies. Additionally, patients with IBS were analyzed for complete blood cell counts, metabolic factors, erythrocyte sedimentation rates, and levels of C-reactive protein and thyroid-stimulating hormone. Any subjects found to have CD-associated antibodies were offered esophagogastroduodenoscopy and duodenal biopsy analysis.

RESULTS

Of patients with NC-IBS, 7.3% had abnormal results for CD-associated antibodies, compared with 4.8% of controls (adjusted odds ratio, 1.49; 95% confidence interval: 0.76-2.90; P=.25). Within the NC-IBS group, 6.51% had antibodies against gliadin, 1.22% against tissue transglutaminase, and 0.61% against endomysium (P>.05 vs controls for all antibodies tested). CD was confirmed in 0.41% of patients in the NC-IBS group and 0.44% of controls (P>.99).

CONCLUSIONS

Although CD-associated antibodies are relatively common, the prevalence of CD among patients with NC-IBS is similar to that among controls in a large US population. These findings challenge recommendations to routinely screen patients with NC-IBS for CD. More than 7% of patients with NC-IBS had CD-associated antibodies, suggesting that gluten sensitivity might mediate IBS symptoms; further studies are needed.

Persistently positive gliadin antibodies without transglutaminase antibodies in the elderly: gluten intolerance beyond coeliac disease

BACKGROUND

The specificity of the conventional gliadin antibody test is considered low.

AIMS

We explored whether gliadin antibody(AGA)-positivity without tissue transglutaminase antibodies (tTGA) is persistent in the elderly population and whether such positivity indicates overt or potential coeliac disease in genetically predisposed individuals.

METHODS

AGA and tissue transglutaminase antibody were measured in 2089 elderly individuals twice with a three-year interval. AGA-positive but tissue transglutaminase antibody-negative subjects with coeliac-type human leucocyte antigen (HLA) were examined and underwent gastroduodenal endoscopy (cases). Small-bowel mucosal villous morphology and densities of CD3+ and γδ+ intraepithelial lymphocytes and the occurrence of tissue transglutaminase-specific IgA deposits were analysed. Randomly selected persistently AGA-negative age- and sex-matched subjects served as controls.

RESULTS

AGA-positivity was persistent in 81% of those initially positive. Amongst the 49 clinically studied and 36 endoscopied cases only one (2.8%) had coeliac disease. Many (54%) showed signs of inflammation in the biopsy, without villous atrophy. Coeliac-type HLA was not over-represented in the persistently AGA-positive compared to the general population. Persistently AGA-positive coeliac-type HLA-positive subjects had more gastrointestinal symptoms than AGA-negative controls.

CONCLUSIONS

AGA-positivity is often persistent. Overt coeliac disease is seldom found behind persistent AGA-positivity, but this characteristic is associated with mucosal inflammation and gastrointestinal symptoms at least in HLA-positive individuals.

The molecular basis for oat intolerance in patients with celiac disease

BACKGROUND

Celiac disease is a small intestinal inflammatory disorder characterized by malabsorption, nutrient deficiency, and a range of clinical manifestations. It is caused by an inappropriate immune response to dietary gluten and is treated with a gluten-free diet. Recent feeding studies have indicated oats to be safe for celiac disease patients, and oats are now often included in the celiac disease diet. This study aimed to investigate whether oat intolerance exists in celiac disease and to characterize the cells and processes underlying this intolerance.

METHODS AND FINDINGS

We selected for study nine adults with celiac disease who had a history of oats exposure. Four of the patients had clinical symptoms on an oats-containing diet, and three of these four patients had intestinal inflammation typical of celiac disease at the time of oats exposure. We established oats-avenin-specific and -reactive intestinal T-cell lines from these three patients, as well as from two other patients who appeared to tolerate oats. The avenin-reactive T-cell lines recognized avenin peptides in the context of HLA-DQ2. These peptides have sequences rich in proline and glutamine residues closely resembling wheat gluten epitopes. Deamidation (glutamine-->glutamic acid conversion) by tissue transglutaminase was involved in the avenin epitope formation.

CONCLUSIONS

We conclude that some celiac disease patients have avenin-reactive mucosal T-cells that can cause mucosal inflammation. Oat intolerance may be a reason for villous atrophy and inflammation in patients with celiac disease who are eating oats but otherwise are adhering to a strict gluten-free diet. Clinical follow-up of celiac disease patients eating oats is advisable.