Absence of somatization in non-coeliac gluten sensitivity

Effects of gluten on dyspeptic symptoms: a systematic review and meta-analysis of clinical trials

CONTEXT

Research on the effects of gluten on dyspeptic symptoms has shown conflicting results.

OBJECTIVE

The aim of this systematic review and meta-analysis of clinical trials was to assess the effects of gluten on dyspeptic symptoms.

DATA SOURCES

A systematic search of the PubMed, ISI Web of Science, Scopus, Cochrane, and Embase online databases was performed up to May 2022.

DATA EXTRACTION

Randomized controlled trials (RCTs) and non-RCTs that examined the impact of a gluten-free diet, a low-gluten diet, or a gluten challenge on dyspeptic symptoms, including early satiety, epigastric pain, bloating, and nausea, were selected independently by 2 authors. The GRADE (Grading of Recommendations Assessment, Development, and Evaluation) framework was used to assess the certainty of the evidence. Results were pooled using a random-effects model and expressed as weighted mean differences (WMDs) and 95%CIs.

DATA ANALYSIS

Of the 7641 citations retrieved, 27 articles (18 RCTs and 9 non-RCTs) were included in the systematic review. Of those, 5 RCTs were eligible for the meta-analysis. The pooled results indicated that gluten challenge significantly increased the severity of bloating (WMD = 0.67; 95%CI, 0.37-0.97; I2 = 81.8%; n = 6), early satiety (WMD = 0.91; 95%CI, 0.58-1.23; I2 = 27.2%; n = 5), and epigastric pain (WMD = 0.46; 95%CI, 0.17-0.75; I2 = 65.8%; n = 6). However, the effect of gluten challenge on the severity of nausea (WMD = 0.13; 95%CI, -0.17 to 0.43; I2 = 0.0%, n = 5) was nonsignificant.

CONCLUSION

Gluten challenge significantly worsened dyspeptic symptoms, including bloating, early satiety, and epigastric pain, but did not affect nausea. These findings suggest that gluten restriction could be efficient in reducing dyspeptic symptoms. Well-designed large RCTs recruiting homogenous groups of patients with functional dyspepsia are needed to clarify the effectiveness of gluten restriction on dyspeptic symptoms.

Non-Celiac Gluten/Wheat Sensitivity: Clinical Characteristics and Microbiota and Mycobiota Composition by Response to the Gluten Challenge Test

The aims of this observational “proof-of-concept” study were to analyze the clinical/psychological characteristics and gut microbiota/mycobiota composition of individuals with suspected non-celiac gluten/wheat sensitivity (NCGS/WS) according to responses to the double-blind-placebo-controlled (DBPC) crossover gluten challenge test. Fifty individuals with suspected NCGS/WS were subjected to the DBPC challenge test; anthropometric measurements, psychometric questionnaires, and fecal samples were collected. Twenty-seven (54%) participants were gluten responsive (NCGS), and 23 were placebo responsive, with an order effect. NCGS individuals displayed a significantly lower risk of eating disorders and a higher mental health score when compared to placebo-responsive participants, confirmed by multiple logistic regression analyses (OR = 0.87; 95% CI 0.76–0.98, p = 0.021, and OR = 1.30; 95% CI 1.06–1.59, p = 0.009, respectively). Principal coordinate analyses based on microbiota composition showed a separation by the DBPC response (p = 0.039). For Bacteroides (p = 0.05) and Parabacteroides (p = 0.007), the frequency of amplicon sequence variants was lower, and that for Blautia (p = 0.009) and Streptococcus (p = 0.004) was higher in NCGS individuals at multiple regression analyses. No difference in the mycobiota composition was detected between the groups. In conclusion, almost half of the individuals with suspected gluten sensitivity reported symptoms with placebo; they showed lower mental health scores, increased risk for eating disorders, and a different gut microbiota composition.

No major reduction in bone mineral density after long-term treatment of patients with Celiac Disease

BACKGROUND

At time of diagnosis, patients with celiac disease (CD) have been shown to have lower bone mineral density (BMD) than healthy controls. It is unclear whether adult patients with CD can regain a normal BMD after treatment with a gluten-free diet (GFD).

METHODS

Patients diagnosed with CD as adults, who had been treated with GFD for a minimum of two years, were examined by dual energy X-ray absorptiometry (DXA) to determine BMD at femoral neck and spine L2-4. Adherence to GFD was measured using the Celiac Disease Adherence Test (CDAT) scoring tool.

RESULTS

143 CD patients underwent DXA assessment, mean age was 55.8 years and mean treatment duration was 9.3 years. 67% of the patients were women, and 51% of these were postmenopausal. The prevalence of low bone mass (Z-score ≤ -1.0) was 18.2% (95%CI: 12.7-25.3%) at femoral neck and 23.1% (95%CI: 16.9-30.6%) at spine L2-4. An increase in low bone density prevalence at spine L2-4 compared to the expected prevalence (p = 0.016) was limited to the postmenopausal women. In a multiple regression analysis, only postmenopausal status and poor adherence to GFD was independently associated with reduced bone density, this however limited to spine L2-4.

CONCLUSION

Our study shows a small increase in the prevalence of low bone density at lumbar spine limited to the postmenopausal women. The main finding is that the majority of the CD patients after two years of treatment with GFD had a normal bone density when adjusted for age, gender, ethnicity and weight.

CD38 expression on gluten-specific T cells is a robust marker of gluten re-exposure in coeliac disease

Background

Increasing efforts are being put into new treatment options for coeliac disease (CeD), a chronic disorder of the small intestine induced by gluten. Interleukin-2 (IL-2) and gluten-specific CD4 + T cells increase in the blood after four hours and six days, respectively, following a gluten challenge in CeD patients. These responses are unique to CeD and are not seen in controls. We aimed to evaluate different markers reflecting a recall response to gluten exposure that may be used to monitor therapy.

Methods

CeD patients on a gluten-free diet underwent a one- (n = 6) or three-day (n = 7) oral gluten challenges. We collected blood samples at several time points between baseline and day 8, and monitored gluten-specific CD4 + T cells for their frequency and CD38 expression using HLA-DQ:gluten tetramers. We assessed the IL-2 concentration in plasma four hours after the first gluten intake.

Results

The frequency of gut-homing, tetramer-binding, CD4 + effector memory T (tetramer + β7 + T_EM) cells and the IL-2 concentration measured shortly after the first dose of gluten increased significantly after the one- and three-day gluten challenges, but large interindividual differences were exhibited. The frequency of tetramer + β7 + T_EM plateaued between days 6 and 8 and was lower after the one-day challenge. We observed a consistent increase in CD38 expression on tetramer + β7 + T_EM cells and did not find a significant difference between the one- and three-day challenges.

Conclusions

The optimal time points for monitoring therapy response in CeD after a three-day oral gluten challenge is four hours for plasma IL-2 or six to eight days for the frequency of tetramer + β7 + T_EM cells, but both these parameters involved large interindividual differences. In contrast, CD38 expression on tetramer + β7 + T_EM cells increased uniformly and irrespectively of the length of gluten challenge, suggesting that this parameter is more suited for monitoring drug efficacy in clinical trials for CeD.

A randomised, double-blind, cross-over trial to evaluate bread, in which gluten has been pre-digested by prolyl endoprotease treatment, in subjects self-reporting benefits of adopting a gluten-free or low-gluten diet

The aim of the present study was to determine if the enzyme Aspergillus niger prolyl endoprotease (ANPEP), which degrades the immunogenic proline-rich residues in gluten peptides, can be used in the development of new wheat products, suitable for gluten-sensitive (GS) individuals. We have carried out a double-blind, randomised, cross-over trial with two groups of adults; subjects, self-reporting benefits of adopting a gluten-free or low-gluten diet (GS, n 16) and a control non-GS group (n 12). For the trial, volunteers consumed four wheat breads: normal bread, bread treated with 0·8 or 1 % ANPEP and low-protein bread made from biscuit flour. Compared with controls, GS subjects had a favourable cardiovascular lipid profile - lower LDL (4·0 (sem 0·3) v. 2·8 (sem 0·2) mmol/l; P=0·008) and LDL:HDL ratio (3·2 (sem 0·4) v. 1·8 (sem 0·2); P=0·005) and modified haematological profile. The majority of the GS subjects followed a low-gluten lifestyle, which helps to reduce the gastrointestinal (GI) symptoms severity. The low-gluten lifestyle does not have any effect on the quality of life, fatigue or mental state of this population. Consumption of normal wheat bread increased GI symptoms in GS subjects compared with their habitual diet. ANPEP lowered the immunogenic gluten in the treated bread by approximately 40 %. However, when compared with the control bread for inducing GI symptoms, no treatment effects were apparent. ANPEP can be applied in the production of bread with taste, texture and appearance comparable with standard bread.

The Role of a Low Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyol Diet in Nonceliac Gluten Sensitivity

Background

Nonceliac gluten sensitivity (NCGS) is a recently defined clinical entity characterized by intestinal and extraintestinal symptoms associated with gluten ingestion in individuals in whom celiac disease (CD) or wheat allergy (WA) has been excluded. Despite its name and definition, gluten has been shown to precipitate symptoms in only 16–30% of these patients. In addition to gluten, other components of wheat, including fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs), alpha-amylase trypsin inhibitors (ATIs) and wheat germ agglutinin have been implicated in the causation of the symptoms of NCGS, with FODMAPs garnering the most attention. We present a review of the existing literature evaluating the role of FODMAPs in NCGS symptomatology.

Methods

A systematic review of PubMed, Cochrane, EMBASE, and Google Scholar for keywords fructans, non-celiac gluten sensitivity, NCGS, FODMAPs, and gluten-free diet (GFD) was conducted through a series of advanced searches. Articles related to the use of fructans or FODMAPs were analyzed.

Results

FODMAPs were found to be associated with gastrointestinal and extraintestinal symptoms in NCGS.

Conclusions

A low FODMAP diet has potential for improvement of clinical symptoms in NCGS. In addition, some evidence suggests an additional benefit to simultaneous adherence to both low FODMAP diet and GFD.

Skepticism Regarding Vaccine and Gluten-Free Food Safety Among Patients with Celiac Disease and Non-celiac Gluten Sensitivity

BACKGROUND

There has been a marked increase in the adoption of the gluten-free (GF) diet.

AIMS

To query individuals with celiac disease (CD) and non-celiac gluten sensitivity (NCGS) on their beliefs toward the health effects of gluten, and safety of vaccines and GF food products.

METHODS

We distributed a Web-based survey to individuals with CD and NCGS on a CD center e-mail list. We used univariate and multivariate analysis to compare responses of respondents with CD and NCGS.

RESULTS

The overall response rate was 27% (NCGS n = 217, CD n = 1291). Subjects with NCGS were more likely than those with CD to disagree with the statement that "vaccines are safe for people with celiac disease" (NCGS 41.3% vs. CD 26.4% (p < 0.0001), and were more likely to decline vaccination when offered (30.9 vs. 24.2%, p = 0.007). After adjusting for age and gender, NCGS subjects were more likely than CD subjects to avoid genetically modified (GMO) foods (aOR 2.30; 95% CI 1.71-3.10), eat only organic products (aOR 2.87; 95% CI 2.04-4.03), believe that the FDA is an unreliable source of information (aOR 1.82, 95% CI 1.26-2.64), and believe a GF diet improves energy and concentration (aOR 2.52; 95% CI 1.86-3.43).

CONCLUSIONS

Subjects with NCGS were more likely than those with CD to have doubts about vaccine safety and believe in the value of non-GMO and organic foods. Our findings suggest that the lack of reliable information on gluten and its content in food and medications may reinforce beliefs that result in a detriment to public health.

Extra-intestinal manifestations of non-celiac gluten sensitivity: An expanding paradigm

Non celiac gluten sensitivity (NCGS) is a syndrome characterized by a cohort of symptoms related to the ingestion of gluten-containing food in subjects who are not affected by celiac disease (CD) or wheat allergy. The possibility of systemic manifestations in this condition has been suggested by some reports. In most cases they are characterized by vague symptoms such as ‘foggy mind’, headache, fatigue, joint and muscle pain, leg or arm numbness even if more specific complaints have been described. NCGS has an immune-related background. Indeed there is a strong evidence that a selective activation of innate immunity may be the trigger for NCGS inflammatory response. The most commonly autoimmune disorders associated to NCGS are Hashimoto thyroiditis, dermatitis herpetiformis, psoriasis and rheumatologic diseases. The predominance of Hashimoto thyroiditis represents an interesting finding, since it has been indirectly confirmed by an Italian study, showing that autoimmune thyroid disease is a risk factor for the evolution towards NCGS in a group of patients with minimal duodenal inflammation. On these bases, an autoimmune stigma in NCGS is strongly supported; it could be a characteristic feature that could help the diagnosis and be simultaneously managed. A possible neurological involvement has been underlined by NCGS association with gluten ataxia, gluten neuropathy and gluten encephalopathy. NCGS patients may show even psychiatric diseases such as depression, anxiety and psychosis. Finally, a link with functional disorders (irritable bowel syndrome and fibromyalgia) is a topic under discussion. In conclusion, the novelty of this matter has generated an expansion of literature data with the unavoidable consequence that some reports are often based on low levels of evidence. Therefore, only studies performed on large samples with the inclusion of control groups will be able to clearly establish whether the large information from the literature regarding extra-intestinal NCGS manifestations could be supported by evidence-based agreements.

Psychotropic medication use among patients with celiac disease

BACKGROUND

Celiac disease is a multi-system disorder with manifestations that may result in psychiatric disorders. We assessed the prevalence of medication use to treat psychiatric disorders in celiac disease patients.

METHODS

We conducted a cross-sectional study of patients undergoing esophagogastroduodenoscopy over 9-years at a celiac disease referral center. We compared the prevalence of psychotropic medication use among celiac disease patients (n = 1293) to a control group (n = 1401) with abdominal pain or reflux.

RESULTS

Among all patients the mean age was 48.4 years, most were female (69.5%), and 22.7% used any psychotropic medication. There was no difference between overall psychotropic medication use among celiac disease patients and controls (23.9% vs 21.8%, OR 1.16; 95% CI 0.96-1.39, p = 0.12). However, those with celiac disease were more likely to use antidepressants on univariate (16.4% vs 13.4%, p = 0.03) and multivariate analysis (OR 1.28; 95% CI 1.03-1.59; p = 0.03). Use of psychotropic medications was not associated with disease duration or mode of presentation of celiac disease.

CONCLUSIONS

Celiac disease patients use psychotropic medications at similar rates as those with other gastrointestinal diseases, though subgroup analysis suggests they may use more antidepressants. Future studies should investigate whether celiac disease is associated with mood disorders that are not treated with medications.

Fructan, Rather Than Gluten, Induces Symptoms in Patients With Self-Reported Non-Celiac Gluten Sensitivity

BACKGROUND & AIMS

Non-celiac gluten sensitivity is characterized by symptom improvement after gluten withdrawal in absence of celiac disease. The mechanisms of non-celiac gluten sensitivity are unclear, and there are no biomarkers for this disorder. Foods with gluten often contain fructans, a type of fermentable oligo-, di-, monosaccharides and polyols. We aimed to investigate the effect of gluten and fructans separately in individuals with self-reported gluten sensitivity.

METHODS

We performed a double-blind crossover challenge of 59 individuals on a self-instituted gluten-free diet, for whom celiac disease had been excluded. The study was performed at Oslo University Hospital in Norway from October 2014 through May 2016. Participants were randomly assigned to groups placed on diets containing gluten (5.7 g), fructans (2.1 g), or placebo, concealed in muesli bars, for 7 days. Following a minimum 7-day washout period (until the symptoms induced by the previous challenge were resolved), participants crossed over into a different group, until they completed all 3 challenges (gluten, fructan, and placebo). Symptoms were measured by Gastrointestinal Symptom Rating Scale Irritable Bowel Syndrome (GSRS-IBS) version. A linear mixed model for analysis was used.

RESULTS

Overall GSRS-IBS scores differed significantly during gluten, fructan, and placebo challenges; mean values were 33.1 ± 13.3, 38.6 ± 12.3, and 34.3 ± 13.9, respectively (P = .04). Mean scores for GSRS-IBS bloating were 9.3 ± 3.5, 11.6 ± 3.5, and 10.1 ± 3.7, respectively, during the gluten, fructan, and placebo challenges (P = .004). The overall GSRS-IBS score for participants consuming fructans was significantly higher than for participants consuming gluten (P = .049), as was the GSRS bloating score (P = .003). Thirteen participants had the highest overall GSRS-IBS score after consuming gluten, 24 had the highest score after consuming fructan, and 22 had the highest score after consuming placebo. There was no difference in GSRS-IBS scores between gluten and placebo groups.

CONCLUSIONS

In a randomized, double-blind, placebo-controlled crossover study of individuals with self-reported non-celiac gluten sensitivity, we found fructans to induce symptoms, measured by the GSRS-IBS. Clinicaltrials.gov no: NCT02464150.

Dietary therapies for functional bowel symptoms: Recent advances, challenges, and future directions

BACKGROUND

Functional gastrointestinal symptoms in irritable bowel syndrome (IBS) and quiescent inflammatory bowel disease (IBD) cause significant morbidity and a reduction in quality of life. Multiple dietary therapies are now available to treat these symptoms, but supporting evidence for many is limited. In addition to a further need for studies demonstrating efficacy and mechanism of action of dietary therapies, the risk of nutritional inadequacy, alterations to the microbiome and changes in quality of life are key concerns requiring elucidation. Identifying predictors of response to dietary therapy is an important goal as management could be tailored to the individual to target specific dietary components, and thereby reduce the level of dietary restriction necessary.

PURPOSE

This review discusses the available dietary therapies to treat symptoms in patients with IBS and patients with quiescent IBD suffering from IBS symptoms, with the aim to understand where current dietary evidence lies and how to move forward in dietary research in this field.

Depression and insomnia among individuals with celiac disease or on a gluten-free diet in the USA: results from a national survey

BACKGROUND

There is uncertainty regarding the prevalence of psychiatric illnesses in patients with celiac disease (CD) and people who avoid gluten (PWAG) without a diagnosis of CD.

PARTICIPANTS AND METHODS

We obtained data from 22 274 participants from the 2009-2014 National Health and Nutrition Examination Survey to compare the prevalence of depression, insomnia, quality-of-life variables, and psychotropic medication use in CD participants and PWAGs to controls. We used multivariable logistic regression to assess for independent associations between CD/PWAG status and the outcomes of these variables.

RESULTS

Depression was present in 8.2% of controls compared with 3.9% of participants with CD (P=0.18) and 2.9% of PWAGs (P=0.002). After adjustment for age, sex, race, income, and access to healthcare, PWAGs maintained lower odds of depression compared with controls (odds ratio=0.25; 95% confidence interval: 0.12-0.51; P=0.0001). The prevalence estimates of sleep difficulty among controls (27.3%) compared to participants with CD or PWAGs were 37.7% (P=0.15) and 34.1% (P=0.11). Those with diagnosed CD had increased odds of sleep difficulty (odds ratio=2.41; 95% confidence interval 1.04-5.60), but this was no longer significant after multivariable adjustment (P=0.17).

CONCLUSION

Among a nationally representative US sample, participants with CD overall showed no increased odds of depression or sleep difficulty. PWAGs showed lower odds of depression compared with controls. Future research should investigate the relationship between a diagnosis of CD and the development of psychiatric conditions.

The perspective of celiac disease patients on emerging treatment options and non-celiac gluten sensitivity

BACKGROUND

Non-celiac gluten sensitivity (NCGS) and emerging treatment options are hot topics in the celiac disease (CeD) scientific literature. However, very little is known about the perspective on these issues of CeD patients.

METHODS

We performed a large patient survey among unselected CeD patients in Switzerland.

RESULTS

A total of 1689 patients were analyzed. 57.5% have previously heard of NCGS. 64.5% believe in the existence of this entity. Regarding a potential influence of NCGS on CeD awareness, 31.7% show a positive and 27.5% a negative perception. Patients with prior use of alternative medicine and women more often have heard of and believe in the existence of NCGS vs. those never having used alternative methods and men, respectively (66.9 vs. 56.9%, p=0.001 and 78.5 vs. 69.0%, p=0.001; 60.7 vs. 44.2%, p<0.001 and 71.0 vs. 60.8%, p=0.002). Women and patients ≥30 years more often show a negative attitude towards NCGS (32.2% vs. 24.8%, p=0.024 and 32.2% vs. 24.2%, p=0.018). With regard to emerging treatment options for CeD, 43.3% have previously heard of novel agents, more women than men (46.0 vs. 38.0%, p=0.019).

CONCLUSIONS

Perception of and attitude towards NCGS differ depending on sex, age and prior use of alternative medicine. Knowledge of the progress towards emerging treatment options is currently limited.

Wheat challenge in self-reported gluten sensitivity: a comparison of scoring methods

BACKGROUND

The condition non-coeliac gluten sensitivity (NCGS) is clinically similar to coeliac disease, but lack objective diagnostic criteria. Symptom relief on gluten-free diet followed by gluten containing food challenge may confirm the condition in clinical settings.

AIM

To describe the results of an open bread challenge in patients with suspected NCGS, and to compare the results with recently suggested cut-offs for symptom change.

MATERIAL AND METHODS

Fifty-six patients (12 males) self-instituted on gluten-free diet with negative coeliac disease diagnostics were examined for NCGS by an open bread challenge. Symptoms were reported by Gastrointestinal Symptom Rating Scale, IBS-version (GSRS-IBS) and visual analogue scale (VAS). Results were retrospectively compared to the Salerno and Monash cut-offs for symptom change.

RESULTS

Forty-seven patients were diagnosed with NCGS. Total GSRS-IBS score and overall symptoms by VAS increased significantly in NCGS (p < .001), but not in non-NCGS patients (p < .12 and p = .08, respectively). Total GSRS-IBS challenge score and overall symptoms by VAS were significantly higher in NCGS than in non-NCGS patients (53 vs. 37, p = .004 and 76 vs. 39 mm, p = .02, respectively). Applying the Salerno and Monash cut-offs, 63 and 75% would be classified with NCGS, respectively. According to total GSRS-IBS absolute agreement was lowest between clinician's diagnosis and Salerno cut-off (63%) and highest between Salerno and Monash cut-offs (88%).

CONCLUSION

Clinician diagnosed 85% with NCGS. The proportion of NCGS was lower according to the Salerno and Monash cut-offs. The Salerno cut-off should be the starting point for a common definition of symptom change.

Long-term mucosal recovery and healing in celiac disease is the rule - not the exception

OBJECTIVE

The prevalence of persistent villous atrophy (VA) in patients with celiac disease (CD) on a gluten-free diet (GFD) varies greatly between studies. Most studies show a relatively high prevalence of mucosal atrophy and inflammation in treated patients, a finding which have led to a concept of non-responsive CD. Few studies have examined the prevalence of long-term mucosal healing. Our study aimed to determine the extent of mucosal healing in a cohort of Norwegian patients with CD treated with GFD for several years.

MATERIALS AND METHODS

Adult patients diagnosed with VA between 1989 and 2009 were included. We performed a follow-up gastroscopy with duodenal biopsies. Two pathologists evaluated the biopsies according to the Marsh-Oberhuber classification. Mucosal healing was defined as Marsh 0 while mucosal recovery was defined as Marsh 0-2.

RESULTS

Duodenal biopsies were obtained from 127 adult patients with established CD. After a follow-up time of 8.1 years (median, range 2.3-22.3), 103 (81%) of the patients showed mucosal healing, 120 patients (94%) showed mucosal recovery, and 7 patients (6%) showed persistent VA. In addition, 103 of the 127 patients (81%) had undergone a routine follow-up biopsy 12.6 months (median, range 5.2-28.8) after diagnosis. At the time of the routine follow-up, only 52 of these patients (50.5%) had achieved mucosal recovery.

CONCLUSIONS

Although half of the patients had persistent VA at the time of routine follow-up, both long-term mucosal recovery and healing is possible for the vast majority of adult patients with CD.

Randomised clinical study: gluten challenge induces symptom recurrence in only a minority of patients who meet clinical criteria for non-coeliac gluten sensitivity

BACKGROUND

It is unknown whether symptoms in non-coeliac patients (non-CD) meeting clinical diagnostic criteria for noncoeliac gluten sensitivity (NCGS) are specifically triggered by gluten.

AIM

To assess gluten sensitivity in patients diagnosed with NCGS.

METHODS

We studied 35 non-CD subjects (31 females) that were on a gluten-free diet (GFD), in a double-blind challenge study. Participants were randomised to receive either gluten-containing flour or gluten-free flour for 10 days, followed by a 2-week washout period and were then crossed over. The main outcome measure was their ability to identify which flour contained gluten. Secondary outcome measures were based upon Gastrointestinal Symptoms Rating Scale (GSRS) scores.

RESULTS

The gluten-containing flour was correctly identified by 12 participants (34%), who were classified as having NCGS. Their mean GSRS dimension scores were significantly higher following gluten challenge compared to baseline. The scores were: pain, 1.7 ± 0.8 vs. 2.6 ± 1.0; reflux, 1.6 ± 0.5 vs. 2.2 ± 0.9; indigestion, 1.9 ± 0.7 vs. 3.2 ± 1.1; diarrhoea, 1.6 ± 0.7 vs. 2.9 ± 1.5 and constipation, 1.9 ± 0.9 vs. 2.9 ± 1.3. Seventeen participants (49%) erroneously considered the gluten-free flour to contain gluten. Their mean GSRS dimension scores were significantly higher following gluten-free flour challenge compared to baseline. The scores were: pain, 1.6 ± 0.9 vs. 3.0 ± 0.9; reflux, 1.4 ± 0.5 vs. 2.3 ± 1.1; indigestion, 2.0 ± 1.1 vs. 3.7 ± 1.1; diarrhoea, 1.6 ± 0.7 vs. 3.0 ± 1.2 and constipation, 1.6 ± 0.9 vs. 2.6 ± 1.3. The other six participants (17%) were unable to distinguish between the flours.

CONCLUSION

Double-blind gluten challenge induces symptom recurrence in just one-third of patients fulfilling the clinical diagnostic criteria for non-coeliac gluten sensitivity.

The spectrum of noncoeliac gluten sensitivity

The past 5 years have seen an increase in the use of a gluten-free diet outside a diagnosis of coeliac disease or IgE-mediated wheat allergy. This trend has led to the identification of a new clinical entity termed noncoeliac gluten sensitivity (NCGS). In this Review, we discuss the evidence for NCGS as demonstrated by the results of double-blind, placebo-controlled dietary rechallenge studies. Furthermore, the characteristic phenotype of individuals with NCGS is described as well as the symptom manifestations commonly reported after gluten exposure, which include intestinal symptoms consistent with IBS, and extraintestinal symptoms such as neurological dysfunction, psychological disturbances, fibromyalgia and skin rash. Moreover, emerging evidence suggests that NCGS can be associated with organic gastrointestinal pathologies, such as IBD, in which its presence might be a reflection of severe or stricturing disease. However, NCGS is not without its controversies and uncertainties, in particular pertaining to whether it is gluten or nongluten components of the grain evoking symptoms; evidence suggests that fermentable carbohydrates, amylase trypsin inhibitors and wheat-germ agglutinin can also be responsible culprits. Finally, we discuss the novel techniques that might help diagnose NCGS in the future.

Coeliac disease - from genetic and immunological studies to clinical applications

Coeliac disease is a common and important gastrointestinal disease. It affects at least 1%, most Western European populations and in Nordic countries it is even more frequent. It is strongly associated with certain Human Leukocyte Antigen-DQ genes and triggered by ingestion of wheat gluten and related cereals from rye and barley. The diagnosis relies on a combination of clinical signs, serology and small intestinal biopsy. Work during the last couple of decades has shown that gluten-specific, Human Leukocyte Antigen-DQ-restricted T-cells in the intestinal mucosa are of paramount importance in the disease process. The gluten peptides are chemically modified by the endogenous enzyme transglutaminase 2, the same enzyme that serves as target in today's sensitive serological tests for coeliac disease. The increasing knowledge on the disease process allows for development of improved diagnosis, patient care and new treatment modalities.

Wheat-related disorders reviewed: making a grain of sense

Wheat-related disorders have become a growing area of clinical and scientific interest and can be categorized broadly as: autoimmune-mediated; allergic; and non-autoimmune/non-allergic conditions. Non-celiac gluten sensitivity (NCGS) and non-celiac wheat sensitivity (NCWS) present on this spectrum as disorders associated with adverse gastrointestinal and extra-intestinal manifestations following exposure to gluten and/or other wheat-related constituents. NCGS/NCWS is increasingly considered in patients with unexplained symptoms after the exclusions of celiac disease and wheat allergy. As objective diagnostic data and specific biomarkers are lacking, response to a gluten-free/wheat-free diet can confirm the presence of NCGS/NCWS. An association with irritable bowel syndrome has been detected, and the effects of other food components, such as fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, may contribute. Our organization and synthesis of extant knowledge pertaining to wheat-related disorders may advance current practice and research efforts toward an improved understanding of NCGS/NCWS as an evolving clinical entity.

Non-celiac gluten sensitivity: a work-in-progress entity in the spectrum of wheat-related disorders

Non-celiac gluten sensitivity is an undefined syndrome with gastrointestinal and extra-intestinal manifestations triggered by gluten in patients without celiac disease and wheat allergy. The pathogenesis involves immune-mediated mechanisms requiring further research. Symptoms disappear in a few hours or days after gluten withdrawal and recur rapidly after gluten ingestion. Besides gluten, other wheat proteins as well as fermentable oligo-, di-, mono-saccharides and polyols (FODMAPs) may contribute to this syndrome. This syndrome occurs mainly in young women, being rare in children. Its prevalence ranges from 0.6% to 6%, based on primary or tertiary care center estimates. No biomarker is available, but half of patients tests positive for IgG anti-gliadin antibodies, which disappear quickly after gluten-free diet together with symptoms. Also, genetic markers are still undefined. Although currently limited to a research setting, double-blind, placebo-controlled, cross-over trial strategy is recommended to confirm the diagnosis. Treatment is based on dietary restriction with special care to nutrient intake.

Systematic review: noncoeliac gluten sensitivity

BACKGROUND

Noncoeliac gluten sensitivity (NCGS) is a controversial emerging disorder. Despite reported symptoms related to the ingestion of gluten, NCGS remains a diagnosis based on the exclusion of coeliac disease, given the absence of reliable biomarkers.

AIM

To evaluate the prevalence, diagnostic exclusion of coeliac disease and the efficacy of a gluten-free diet (GFD) for NCGS patients.

METHODS

A PubMed search was performed up to December 2014. According to consensus diagnostic criteria, NCGS was defined as self-reported gluten intolerance, negative coeliac serology and absence of villous atrophy. Studies evaluating the impact of a GFD on patients with irritable bowel syndrome (IBS) were also included.

RESULTS

Prevalence rates of NCGS (0.5-13%) differed widely. Seventeen studies, including 1561 patients (26 children), met the inclusion criteria for NCGS. HLA haplotypes could not be linked to histology [normal or lymphocytic enteritis (LE)] in 1123 NCGS patients. HLADQ2/DQ8 haplotypes were present in 44% of NCGS patients. After advanced diagnostic techniques in 189 NCGS patients combining LE and HLADQ2/DQ8 haplotypes, 39 (20%) were reclassified as coeliac disease. There was a higher than expected family history of coeliac disease and autoimmune disorders in NCGS patients. A GFD resulted in variable results for variable, but significantly improved stool frequency in HLADQ2 positive diarrhoea-predominant IBS patients.

CONCLUSIONS

Prevalence rates for NCGS are extremely variable. A subset of NCGS patients might belong in the so-called 'coeliac-lite' disease. The benefit of a GFD for NCGS patients is currently controversial. HLADQ2 positive diarrhoea-type IBS patients might gain symptom improvement from a GFD.

Coeliac disease and noncoeliac gluten sensitivity

The spectrum of gluten-related disorders was restricted to coeliac disease and wheat allergy, but the new contemporary entity referred to as noncoeliac gluten sensitivity has gained recognition mainly in adults but also in children. Noncoeliac gluten sensitivity is defined as the presence of a variety of symptoms related to gluten ingestion in patients in whom coeliac disease and wheat allergy have been excluded. The pathophysiology and biomarkers of coeliac disease and wheat allergy are well known, but this is not the case for noncoeliac gluten sensitivity. It is also not clear whether noncoeliac gluten sensitivity is caused by consumption of gluten or by consumption of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Randomized trials on noncoeliac gluten sensitivity in children are lacking and are hardly needed to evaluate its role in paediatric patients with gastroenterology to avoid the use of unnecessary restrictive diets in children and interference with proper diagnosis of coeliac disease.

Overview of biomarkers for diagnosis and monitoring of celiac disease

Among the adverse reactions caused by wheat, celiac disease (CD) is the longest studied and best-known pathology. The more recently defined non-celiac gluten sensitivity (NCGS) presents with symptoms which are often indistinguishable from CD. Diagnosis of CD is based on serologic, molecular, and bioptic testing. The IgA anti-transglutaminase (tTG) test is considered highly important, as it shows high sensitivity and specificity and its levels correlate to the degree of intestinal damage. Small bowel biopsy can be avoided in symptomatic patients with IgA anti-tTG levels above 10× the manufacturer's cut-off. Recently, tests of anti-deamidated peptides of gliadin (DGP) have replaced classic anti-native gliadin (AGA) tests. DGP assays have a considerably higher diagnostic accuracy than AGA assays, especially in the IgG class, and can replace anti-tTG tests in patients with selective IgA deficiency. The combination of IgG anti-DGP plus IgA anti-tTG assays show greater sensitivity than a single test, with very high specificity. EMA tests have great diagnostic accuracy but are not recommended by all the latest guidelines because they are observer dependent. Biopsy must still be considered the gold standard for CD diagnosis. HLA-DQ genotyping can be used to screen asymptomatic children and in cases of histology/serology disagreement. About half of NCGS patients are DQ2 positive and have IgG AGA. To diagnose NCGS, first CD and wheat allergy must be excluded; then the wheat dependence of symptoms must be verified by a gluten-free diet and subsequent gluten challenge.

Non-celiac gluten sensitivity: literature review

BACKGROUND

A significant percentage of the general population report problems caused by wheat and/or gluten ingestion, even though they do not have celiac disease (CD) or wheat allergy (WA), because they test negative both for CD-specific serology and histopathology and for immunoglobulin E (IgE)-mediated assays. Most patients report both gastrointestinal and nongastrointestinal symptoms, and all report improvement of symptoms on a gluten-free diet. This clinical condition has been named non-celiac gluten sensitivity (NCGS).

AIM

We attempt to define the current pathogenic, clinical, and diagnostic criteria of this "new" disease, to provide a practical view that might be useful to evaluate, diagnose, and manage NCGS patients.

METHODS

We reviewed the international literature through PubMed and Medline, using the search terms "wheat (hyper)sensitivity," "wheat allergy," "wheat intolerance," "gluten (hyper)sensitivity," and "gluten intolerance," and we discuss current knowledge about NCGS.

RESULTS

It has been demonstrated that patients suffering from NCGS are a heterogeneous group, composed of several subgroups, each characterized by different pathogenesis, clinical history, and, probably, clinical course. NCGS diagnosis can be reached only by excluding CD and WA. Recent evidence shows that a personal history of food allergy in infancy, coexistent atopy, positive for immunoglobulin G (IgG) antigliadin antibodies and flow cytometric basophil activation test, with wheat and duodenal and/or ileum-colon intraepithelial and lamina propria eosinophil counts, could be useful to identify NCGS patients.

CONCLUSIONS

Future research should aim to identify reliable biomarkers for NCGS diagnosis and to better define the different NCGS subgroups. Key teaching points: • Most patients report both gastrointestinal and nongastrointestinal symptoms, and all agree that there is an improvement of symptoms on a gluten-free diet. • NCGS diagnosis can be reached only by excluding celiac disease and wheat allergy. • Patients suffering from NCGS are a heterogeneous group, composed of several subgroups, each characterized by different pathogenesis, clinical history, and, probably, clinical course. • A personal history of food allergy in infancy, coexistent atopy, positive IgG antigliadin antibodies (AGA) and flow cytometric basophil activation test, with wheat and duodenal and/or ileum-colon intraepithelial and lamina propria eosinophil counts, could be useful to identify NCGS patients. • Future research should aim to identify reliable biomarkers for NCGS diagnosis and to better define the different NCGS subgroup.

Coeliac disease: noncoeliac gluten sensitivity--food for thought

Patients with noncoeliac gluten sensitivity (NCGS) can experience a range of gastrointestinal and extraintestinal symptoms. A study has now demonstrated that gluten is independently associated with depression in patients with NCGS. NCGS-associated depression might share similar pathophysiological mechanisms to other neurological manifestations observed in gluten-related disorders, such as ataxia and encephalopathy.

Characteristics of patients who avoid wheat and/or gluten in the absence of Celiac disease

BACKGROUND

Gastrointestinal symptoms that respond to the removal of wheat and/or gluten are becoming more common. Patients who avoid wheat and/or gluten (PWAWG) are a heterogeneous group and predominantly self-diagnosed prior to presenting for clinical evaluation.

SPECIFIC AIM

We characterized PWAWGs seen at a tertiary care referral center and compared them to patients with celiac disease (CD) and subjects in the National Health and Nutrition examination survey (NHANES).

METHODS

This was a cross-sectional study evaluating patients seen by four gastroenterologists at a CD referral center. Baseline characteristics, laboratory values, and medical comorbidities were compared to CD patients who presented at the same center and subjects enrolled in NHANES.

RESULTS

Eighty-four PWAWGs were identified and compared to 585 CD patients and 2,686 NHANES patients. Thirty-two alternative diagnoses were made in 25 (30%) PWAWGs, including small intestinal bacterial overgrowth and fructose/lactose intolerance. When compared to patients with CD, PWAWGs had similar body mass index (BMI, 23.1 vs. 23.5, p = 0.54) and mean hemoglobin value (13.4 vs. 13.3, p = 0.6). When compared to male and female patients in NHANES, BMI, folate, and mean hemoglobin values were lower in PWAWGs. Both male and female PWAWGs had a lower prevalence of hypertension.

CONCLUSION

While there are similarities between CD and PWAWGs that could possibly be due to shared HLA haplotypes or an effect of the gluten-free diet, alternative diagnoses are common in these patients. PWAWGs have a similar cardiovascular profile as CD patients in terms of lower BMI and lower prevalence of hypertension.

Non-celiac gluten sensitivity - why worry?

Wheat, once thought to be a critical ingredient in a healthy diet, has become a major threat, according to public opinion. The term non-celiac gluten sensitivity has been widely adopted to describe a clinical entity characterized by symptoms induced by gluten without the diagnostic criteria found in other gluten-related disorders. However, it has not been shown that gluten per se is involved, and it can be debated if the condition is a disease. Nevertheless, a large number of individuals go gluten-free, avoiding wheat, rye and barley, even without a defined medical cause. In a study in BMC Medicine, Volta and colleagues from Italy report on a large, multicenter attempt to enumerate the prevalence of non-celiac gluten sensitivity in secondary gastroenterology care. They found that approximately 3% of their more than 12,000 patients fulfilled their criteria for non-celiac gluten sensitivity. However, we are still challenged with finding stricter clinical criteria for the condition, developing a usable clinical approach for gluten challenge in these individuals, and understanding the pathogenesis of the condition.

Randomised clinical trial: gluten may cause depression in subjects with non-coeliac gluten sensitivity - an exploratory clinical study

BACKGROUND

Current evidence suggests that many patients with self-reported non-coeliac gluten sensitivity (NCGS) retain gastrointestinal symptoms on a gluten-free diet (GFD) but continue to restrict gluten as they report 'feeling better'.

AIM

To investigate the notion that a major effect of gluten in those with NCGS is on mental state and not necessarily on gastrointestinal symptoms.

METHODS

Twenty-two subjects (24-62 years, five male) with irritable bowel syndrome who had coeliac disease excluded but were symptomatically controlled on a GFD, undertook a double-blind cross-over study. Participants randomly received one of three dietary challenges for 3 days, followed by a minimum 3-day washout before crossing over to the next diet. Challenge gluten-free food was supplemented with gluten (16 g/day), whey (16 g/day) or not supplemented (placebo). End-points included mental state as assessed by the Spielberger State Trait Personality Inventory (STPI), cortisol secretion and gastrointestinal symptoms.

RESULTS

Gluten ingestion was associated with higher overall STPI state depression scores compared to placebo [M = 2.03, 95% CI (0.55-3.51), P = 0.010] but not whey [M = 1.48, 95% CI (-0.14 to 3.10), P = 0.07]. No differences were found for other STPI state indices or for any STPI trait measures. No difference in cortisol secretion was identified between challenges. Gastrointestinal symptoms were induced similarly across all dietary challenges.

CONCLUSIONS

Short-term exposure to gluten specifically induced current feelings of depression with no effect on other indices or on emotional disposition. Gluten-specific induction of gastrointestinal symptoms was not identified. Such findings might explain why patients with non-coeliac gluten sensitivity feel better on a gluten-free diet despite the continuation of gastrointestinal symptoms.

Gluten sensitivity presenting as a neuropsychiatric disorder

There has been increasing recognition in the medical community and the general public of the widespread prevalence of gluten sensitivity. Celiac disease (CD) was initially believed to be the sole source of this phenomenon. Signs and symptoms indicative of nonceliac gluten sensitivity (NCGS), in which classical serum and intestinal findings of CD may be absent, have been frequently reported of late. Clinical manifestations in patients with NCGS are characteristically triggered by gluten and are ameliorated or resolved within days to weeks of commencing a gluten-free diet. Emerging scientific literature contains several reports linking gluten sensitivity states with neuropsychiatric manifestations including autism, schizophrenia, and ataxia. A clinical review of gluten sensitivity is presented alongside a case illustrating the life-changing difference achieved by gluten elimination in a patient with a longstanding history of auditory and visual hallucinations. Physicians in clinical practice should routinely consider sensitivity issues as an etiological determinant of otherwise inexplicable symptoms. Pathophysiologic mechanisms to explain the multisystem symptomatology with gluten sensitivity are considered.

A UK study assessing the population prevalence of self-reported gluten sensitivity and referral characteristics to secondary care

BACKGROUND

Reports suggest that gluten sensitivity (GS) exists in the absence of coeliac disease (CD). This clinical entity has been termed noncoeliac gluten sensitivity (NCGS).

OBJECTIVES

To determine the population prevalence of self-reported GS and referral characteristics to secondary care.

PATIENTS AND METHODS

A UK population-based questionnaire screened for GS and related symptoms. Diagnostic outcomes were also analyzed in patients referred to secondary care with GS. CD diagnosis entailed a positive coeliac serology (endomysial and/or tissue transglutaminase antibodies) plus Marsh 1-3 on duodenal biopsies. NCGS diagnosis was based on exclusion of CD. Clinical comparisons were made between NCGS and CD.

RESULTS

A total of 1002 adults in the population (female 55%, mean age 39 years). The self-reported prevalence for GS was 13% (female 79%, mean age 39.5 years, P<0.0001), with 3.7% consuming a gluten-free diet and 0.8% known to have a doctor diagnosis of CD. Individuals with GS had an increased prevalence of fulfilling the Rome III criteria for irritable bowel syndrome, in comparison with those without GS (20 vs. 3.89%, odds ratio 6.23, P<0.0001).In secondary care 200 GS patients (female 84%, mean age 39.6 years) were investigated, in whom 7% were found to have CD and 93% to have NCGS. All CD patients were human leucocyte antigen DQ2 or DQ8 positive compared with 53% of NCGS cases (P=0.0003). Nutritional deficiencies (P≤0.003), autoimmune disorders (23.1 vs. 9.7%, P=0.0001) and a lower mean BMI (23.7 vs. 25.8, P=0.001) were significantly associated with CD compared with NCGS.

CONCLUSION

GS is commonly self-reported with symptoms suggesting an association with irritable bowel syndrome. The majority of patients have NCGS, an entity which demonstrates clinical and immunologic difference to CD.

Non-celiac gluten sensitivity: clinical relevance and recommendations for future research

BACKGROUND

There has been increasing interest in the entity of Non-Celiac Gluten Sensitivity (NCGS) in recent years; however, it still remains a controversial topic and its pathogenesis is not well understood. Celiac Disease, in contrast, is a well-studied condition that has become increasingly recognized as a prevalent condition arising from a heightened immunological response to gluten. Wheat allergy is an IgE-mediated condition capable of causing a variety of gastrointestinal symptoms. However, the number of patients who have neither celiac disease nor wheat allergy, but appear to derive benefit from a gluten-free diet, is also increasing substantially. The use of the term NCGS as a way of describing this condition has become increasingly prevalent in recent years.

PURPOSE

In this review, we will focus on gastrointestinal manifestations of NCGS and discuss the evidence for the condition and its putative pathogenesis. We will discuss areas of controversy and areas for potential future research.

Gliadin does not induce mucosal inflammation or basophil activation in patients with nonceliac gluten sensitivity

BACKGROUND & AIMS

Nonceliac gluten-sensitive (NCGS) patients report intestinal and extra-intestinal symptoms shortly after ingesting gluten; these symptoms disappear on gluten-free diets, although these patients have no serologic markers of celiac disease or intestinal damage. In fact, there is no evidence for mucosal or serologic modifications in those individuals. We investigated immunologic responses of duodenal mucosa samples and peripheral blood basophils, isolated from NCGS patients, after exposure to gliadin.

METHODS

Participants underwent a complete clinical evaluation to exclude celiac disease while on a gluten-containing diet, a skin prick test to exclude wheat allergy, and upper endoscopy (n = 119) at 2 tertiary medical centers in Italy. Patients were considered to have NCGS based on their symptoms and the current definition of the disorder. Subjects were assigned to the following groups: patients with celiac disease on gluten-free diets (n = 34), untreated patients with celiac disease (n = 35), patients with NCGS (n = 16), or controls (n = 34). Duodenal biopsy samples collected during endoscopy were incubated with gliadin peptides, and levels of inflammatory markers were assessed. Peripheral blood basophils were extracted and incubated with gliadin peptides or a mix of wheat proteins; activation was assessed based on levels of CD203c, CD63, and CD45.

RESULTS

Duodenal mucosa samples collected from 69 patients with celiac disease showed markers of inflammation after incubation with gliadin. Some, but not all, markers of inflammation were detected weakly in biopsy samples from 3 controls and 3 NCGS patients (P = .00 for all markers). There were no significant increases in the levels of CD63 and CD203c in NCGS patients.

CONCLUSIONS

Unlike the duodenal mucosa from patients with celiac disease, upon incubation with gliadin, mucosa from patients with NCGS does not express markers of inflammation, and their basophils are not activated by gliadin. The in vitro gliadin challenge therefore should not be used to diagnose NCGS.

Non-Celiac Gluten sensitivity: the new frontier of gluten related disorders

Non Celiac Gluten sensitivity (NCGS) was originally described in the 1980s and recently a “re-discovered” disorder characterized by intestinal and extra-intestinal symptoms related to the ingestion of gluten-containing food, in subjects that are not affected with either celiac disease (CD) or wheat allergy (WA). Although NCGS frequency is still unclear, epidemiological data have been generated that can help establishing the magnitude of the problem. Clinical studies further defined the identity of NCGS and its implications in human disease. An overlap between the irritable bowel syndrome (IBS) and NCGS has been detected, requiring even more stringent diagnostic criteria. Several studies suggested a relationship between NCGS and neuropsychiatric disorders, particularly autism and schizophrenia. The first case reports of NCGS in children have been described. Lack of biomarkers is still a major limitation of clinical studies, making it difficult to differentiate NCGS from other gluten related disorders. Recent studies raised the possibility that, beside gluten, wheat amylase-trypsin inhibitors and low-fermentable, poorly-absorbed, short-chain carbohydrates can contribute to symptoms (at least those related to IBS) experienced by NCGS patients. In this paper we report the major advances and current trends on NCGS.

Gluten-free diet in gluten-related disorders

A gluten-free diet (GFD) is recommended for all patients with coeliac disease (CD). The spectrum of gluten-related disorders in the early 1980s was simple: CD and dermatitis herpetiformis. In the last few years, wheat allergy, gluten ataxia and noncoeliac gluten sensitivity have become new gluten-related topics. Adherence to GFDs in CD is limited and factors influencing adherence are poorly understood. Noncoeliac gluten sensitivity has stimulated the GFD food industry not only in Australia but all over the world. This article provides an overview of GFD in daily practice.

Mucosal cytokine response after short-term gluten challenge in celiac disease and non-celiac gluten sensitivity

OBJECTIVES

In celiac disease (CD), gluten induces both adaptive and innate immune responses. Non-celiac gluten sensitivity (NCGS) is another form of gluten intolerance where the immune response is less characterized. The aim of our study was to explore and compare the early mucosal immunological events in CD and NCGS.

METHODS

We challenged 30 HLA-DQ2(+) NCGS and 15 CD patients, all on a gluten-free diet, with four slices of gluten-containing bread daily for 3 days. Duodenal biopsy specimens were collected before and after challenge. The specimens were examined for cytokine mRNA by quantitative reverse transcriptase-PCR and for MxA-expression and CD3(+) intraepithelial lymphocytes (IELs) by immunohistochemistry and compared with specimens from untreated CD patients and disease controls.

RESULTS

In CD patients, tumor necrosis factor alpha (P=0.02) and interleukin 8 (P=0.002) mRNA increased after in vivo gluten challenge. The interferon gamma (IFN-γ) level of treated CD patients was high both before and after challenge and did not increase significantly (P=0.06). Four IFN-γ-related genes increased significantly. Treated and untreated CD patients had comparable levels of IFN-γ. Increased expression of MxA in treated CD patients after challenge suggested that IFN-α was activated on gluten challenge. In NCGS patients only IFN-γ increased significantly (P=0.03). mRNA for heat shock protein (Hsp) 27 or Hsp70 did not change in any of the groups. Importantly, we found that the density of IELs was higher in NCGS patients compared with disease controls, independent of challenge, although lower than the level for treated CD patients.

CONCLUSIONS

CD patients mounted a concomitant innate and adaptive immune response to gluten challenge. NCGS patients had increased density of intraepithelial CD3(+) T cells before challenge compared with disease controls and increased IFN-γ mRNA after challenge. Our results warrant further search for the pathogenic mechanisms for NCGS.

Advances in research of non-coeliac gluten sensitivity

Non-celiac gluten sensitivity (NCGS) is a newly recognized clinical entity that is characterized by a wide variety of intestinal or extra-intestinal manifestations, and it may be the most common one in the spectrum of gluten-related disorders. The symptoms of NCGS improve or disappear after gluten withdrawal and relapse if gluten is reintroduced. There are no specific serological markers for NCGS although nearly half of patients are positive for antigliadin IgG antibodies. Since small intestinal biopsy is normal, the double-blind, placebo-controlled food challenge (DBPCFC) and an exclusion of wheat allergy or coeliac disease are necessary for diagnosis. The pathogenesis is still unclear although immunology may play a role in its pathogenesis. This review will summarize our current knowledge about non-coeliac gluten sensitivity and outline pathogenic and epidemiological differences between NCGS and coeliac disease.

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.