Celiac disease: how complicated can it get?

Diagnosing celiac disease in children using oral manifestations

PURPOSE

Celiac disease (CD) may be frequently undiagnosed due to the absence of characteristic gastroenterologic symptoms in many CD patients. Our objective was to diagnose CD by utilizing documented oral manifestations such as Recurrent Aphthous Stomatitis (RAS) and Molar-Incisor Hypomineralization (MIH).

METHODS

The study comprised sixty children who presented with complaints of RAS lesions. The MIH group consisted of 40 children, while the control group comprised 20 children without MIH lesions, ranging in age from 7 to 13 years. After the dental examination, all children were given a questionnaire to assess whether they had any previous history of general symptoms related to CD. Following that, diagnostic testing for celiac disease were conducted, including serological tests such as Tissue transglutaminase IgA (tTG-IgA), Endomysium Antibody (EMA), and Total IgA, as well as genetic tests for HLA-DQ2 and HLA-DQ8.

RESULTS

The statistical analysis, conducted using Fisher's Exact, Yates' Continuity Correction, Fisher Freeman Halton, and Student's t tests, revealed no significant differences between the groups (p < 0.05). Within the MIH group, 3 children exhibited border tTG-IgA values, while another 3 had positive tTG-IgA results. Two of these 6 children had also positive EMA and HLA results. Following a biopsy procedure, these two children were ultimately diagnosed with celiac disease (CD).

CONCLUSIONS

In this study, while children initially presented to the clinic with complaints of recurrent aphthous stomatitis (RAS), 2 children (5% of the MIH group) were diagnosed with CD shortly after the onset of MIH lesions. CD enhanced the likelihood of observing some oral manifestations particularly recurrent aphtous stomatitis and developmental enamel defects. We recommend that dentists be cautious about diagnosing CD when RAS lesions and DEDs and/or MIH lesions are present, whether or not other indications of this systemic disease exist.

Prevalence of delivery mode in an Italian nationwide cohort with celiac disease: a SIGENP multicenter retrospective study (the CD-deliver-IT)

BACKGROUND

Studies have indicated an association between cesarean section (CS), especially elective CS, and an increased risk of celiac disease (CD), but the conclusions of other studies are contradictory. The primary aim of this study (CD-deliver-IT) was to evaluate the rate of CS in a large population of CD patients throughout Italy.  METHODS: This national multicenter retrospective study was conducted between December 2020 and November 2021. The coordinating center was the Pediatric Gastroenterology and Liver Unit of Policlinico Umberto I, Sapienza, University of Rome, Lazio, Italy. Eleven other referral centers for CD have participated to the study. Each center has collected data on mode of delivery and perinatal period of all CD patients referring to the center in the last 40 years.

RESULTS

Out of 3,259 CD patients recruited in different Italian regions, data on the mode of delivery were obtained from 3,234. One thousand nine hundred forty-one (1,941) patients (60%) were born vaginally and 1,293 (40%) by CS (8.3% emergency CS, 30.1% planned CS, 1.5% undefined CS). A statistically significant difference was found comparing median age at time of CD diagnosis of patients who were born by emergency CS (4 years, CI 95% 3.40-4.59), planned CS (7 years, CI 95% 6.02-7.97) and vaginal delivery (6 years, CI 95% 5.62-6.37) (log rank p < 0.0001).

CONCLUSIONS

This is the first Italian multicenter study aiming at evaluating the rate of CS in a large population of CD patients through Italy. The CS rate found in our CD patients is higher than rates reported in the general population over the last 40 years and emergency CS seems to be associated with an earlier onset of CD compared to vaginal delivery or elective CS in our large nationwide retrospective cohort. This suggests a potential role of the mode of delivery on the risk of developing CD and on its age of onset, but it is more likely that it works in concert with other perinatal factors. Further prospective studies on other perinatal factors potentially influencing gut microbiota are awaited in order to address heavy conflicting evidence reaming in this research field.

TRAV26-2 T-Cell Receptor Expression Is Associated With Mucosal Lymphocyte Response to Wheat Proteins in Patients With Functional Dyspepsia

INTRODUCTION

An association between functional dyspepsia (FD) and wheat-containing foods has been reported in observational studies; however, an adaptive response has not been demonstrated. We examined whether antigens present in wheat could provoke a response from FD duodenal lymphocytes.

METHODS

Lamina propria mononuclear cells (LPMCs) were isolated from duodenal biopsies from 50 patients with FD and 23 controls. LPMCs were exposed to gluten (0.2 mg/mL) or gliadin (0.2 mg/mL) for 24 hours. Flow cytometry was performed to phenotype lymphocytes. Quantitative PCR was used to measure the expression of gliadin-associated T-cell receptor alpha variant ( TRAV ) 26-2.

RESULTS

In response to gliadin (but not gluten) stimulation, the effector Th2-like population was increased in FD LPMCs compared with that in controls and unstimulated FD LPMCs. Duodenal gene expression of TRAV26- 2 was decreased in patients with FD compared with that in controls. We identified a positive association between gene expression of this T-cell receptor variant and LPMC effector Th17-like cell populations in patients with FD, but not controls after exposure to gluten, but not gliadin.

DISCUSSION

Our findings suggest that gliadin exposure provokes a duodenal effector Th2-like response in patients with FD, supporting the notion that food antigens drive responses in some patients. Furthermore, these findings suggest that altered lymphocyte responses to wheat proteins play a role in FD pathogenesis.

Positivity of celiac disease-specific antibodies and non-celiac hypersensitivity in psoriasis

INTRODUCTION

Plaque psoriasis and celiac disease are multisystemic diseases. The association of psoriasis and enteropathy with histological changes similar to celiac disease has already been described, and it has also been found that a gluten-free diet improves psoriatic changes. This study assesses the relationship between celiac disease antibodies and psoriasis.

METHODS

The study included 112 participants: 60 with psoriasis in a test group and 52 healthy subjects in a control group. Within the psoriasis group, participants were further divided into two subgroups: one consisting of patients with both psoriasis and psoriatic arthritis (n = 17) and another comprising patients with psoriasis alone (n = 43). After informed consent was obtained, the Dermatology Life Quality Index (DLQI) score and Psoriasis Area and Severity Index (PASI) score were evaluated. Laboratory tests included assessment of anti-deaminated gliadin peptide antibodies (DGP), anti-gliadin antibodies (AGA), and anti-tissue transglutaminase antibodies (tTG).

RESULTS

Immunoglobulin G (IgG) and immunoglobulin A (IgA) DGP antibodies were detected more frequently and at higher serum concentrations in patients with psoriasis compared to healthy controls (p = 0.03, p = 0.04, respectively). Similarly, elevated levels of IgG-tTG antibodies (p = 0.003) and IgA-DGP antibodies (p = 0.02) were observed in the same test group.

CONCLUSIONS

A relationship between positivity to celiac disease antibodies and psoriasis, particularly with regard to AGA, has been identified. Further studies are required to elucidate the nature, pathophysiology, and significance of these findings.

The gut protist Tritrichomonas arnold restrains virus-mediated loss of oral tolerance by modulating dietary antigen-presenting dendritic cells

Loss of oral tolerance (LOT) to gluten, driven by dendritic cell (DC) priming of gluten-specific T helper 1 (Th1) cell immune responses, is a hallmark of celiac disease (CeD) and can be triggered by enteric viral infections. Whether certain commensals can moderate virus-mediated LOT remains elusive. Here, using a mouse model of virus-mediated LOT, we discovered that the gut-colonizing protist Tritrichomonas (T.) arnold promotes oral tolerance and protects against reovirus- and murine norovirus-mediated LOT, independent of the microbiota. Protection was not attributable to antiviral host responses or T. arnold-mediated innate type 2 immunity. Mechanistically, T. arnold directly restrained the proinflammatory program in dietary antigen-presenting DCs, subsequently limiting Th1 and promoting regulatory T cell responses. Finally, analysis of fecal microbiomes showed that T. arnold-related Parabasalid strains are underrepresented in human CeD patients. Altogether, these findings will motivate further exploration of oral-tolerance-promoting protists in CeD and other immune-mediated food sensitivities.

Dimethyl Fumarate and Intestine: From Main Suspect to Potential Ally against Gut Disorders

Dimethyl fumarate (DMF) is a well-characterized molecule that exhibits immuno-modulatory, anti-inflammatory, and antioxidant properties and that is currently approved for the treatment of psoriasis and multiple sclerosis. Due to its Nrf2-dependent and independent mechanisms of action, DMF has a therapeutic potential much broader than expected. In this comprehensive review, we discuss the state-of-the-art and future perspectives regarding the potential repurposing of DMF in the context of chronic inflammatory diseases of the intestine, such as inflammatory bowel disorders (i.e., Crohn's disease and ulcerative colitis) and celiac disease. DMF's mechanisms of action, as well as an exhaustive analysis of the in vitro/in vivo evidence of its beneficial effects on the intestine and the gut microbiota, together with observational studies on multiple sclerosis patients, are here reported. Based on the collected evidence, we highlight the new potential applications of this molecule in the context of inflammatory and immune-mediated intestinal diseases.

Identifying shared genetic architecture between rheumatoid arthritis and other conditions: a phenome-wide association study with genetic risk scores

BACKGROUND

Rheumatoid arthritis (RA) shares genetic variants with other autoimmune conditions, but existing studies test the association between RA variants with a pre-defined set of phenotypes. The objective of this study was to perform a large-scale, systemic screen to determine phenotypes that share genetic architecture with RA to inform our understanding of shared pathways.

METHODS

In the UK Biobank (UKB), we constructed RA genetic risk scores (GRS) incorporating human leukocyte antigen (HLA) and non-HLA risk alleles. Phenotypes were defined using groupings of International Classification of Diseases (ICD) codes. Patients with an RA code were excluded to mitigate the possibility of associations being driven by the diagnosis or management of RA. We performed a phenome-wide association study, testing the association between the RA GRS with phenotypes using multivariate generalized estimating equations that adjusted for age, sex, and first five principal components. Statistical significance was defined using Bonferroni correction. Results were replicated in an independent cohort and replicated phenotypes were validated using medical record review of patients.

FINDINGS

We studied n = 316,166 subjects from UKB without evidence of RA and screened for association between the RA GRS and n = 1317 phenotypes. In the UKB, 20 phenotypes were significantly associated with the RA GRS, of which 13 (65%) were immune mediated conditions including polymyalgia rheumatica, granulomatosis with polyangiitis (GPA), type 1 diabetes, and multiple sclerosis. We further identified a novel association in Celiac disease where the HLA and non-HLA alleles had strong associations in opposite directions. Strikingly, we observed that the non-HLA GRS was exclusively associated with greater risk of the validated conditions, suggesting shared underlying pathways outside the HLA region.

INTERPRETATION

This study replicated and identified novel autoimmune phenotypes verified by medical record review that share immune pathways with RA and may inform opportunities for shared treatment targets, as well as risk assessment for conditions with a paucity of genomic data, such as GPA.

FUNDING

This research was funded by the US National Institutes of Health (P30AR072577, R21AR078339, R35GM142879, T32AR007530) and the Harold and DuVal Bowen Fund.

Gut-kidney axis in IgA nephropathy: Role on mesangial cell metabolism and inflammation

IgA Nephropathy (IgAN) is the commonest primary glomerular disease around the world and represents a significant cause of end-stage renal disease. IgAN is characterized by mesangial deposition of IgA-immune complexes and mesangial expansion. The pathophysiological process includes an abnormally glycosylated IgA1, which is an antigenic target. Autoantibodies specifically recognize galactose-deficient IgA1 forming immune complexes that are amplified in size by the soluble IgA Fc receptor CD89 leading to deposition in the mesangium through interaction with non-classical IgA receptors. The local production of cytokines promotes local inflammation and complement system activation, besides the stimulation of mesangial proliferation. The spectrum of clinical manifestations is quite variable from asymptomatic microscopic hematuria to rapidly progressive glomerulonephritis. Despite all the advances, the pathophysiology of the disease is still not fully elucidated. The mucosal immune system is quoted to be a factor in triggering IgAN and a "gut-kidney axis" is proposed in its development. Furthermore, many recent studies have demonstrated that food intake interferes directly with disease prognosis. In this review, we will discuss how mucosal immunity, microbiota, and nutritional status could be interfering directly with the activation of intrinsic pathways of the mesangial cells, directly resulting in changes in their function, inflammation and development of IgAN.

NK cells contribute to reovirus-induced IFN responses and loss of tolerance to dietary antigen

Celiac disease is an immune-mediated intestinal disorder that results from loss of oral tolerance (LOT) to dietary gluten. Reovirus elicits inflammatory Th1 cells and suppresses Treg responses to dietary antigen in a strain-dependent manner. Strain type 1 Lang (T1L) breaks oral tolerance, while strain type 3 Dearing reassortant virus (T3D-RV) does not. We discovered that intestinal infection by T1L in mice leads to the recruitment and activation of NK cells in mesenteric lymph nodes (MLNs) in a type I IFN-dependent manner. Once activated following infection, NK cells produce type II IFN and contribute to IFN-stimulated gene expression in the MLNs, which in turn induces inflammatory DC and T cell responses. Immune depletion of NK cells impairs T1L-induced LOT to newly introduced food antigen. These studies indicate that NK cells modulate the response to dietary antigen in the presence of a viral infection.

Possible relationship between refractory celiac disease and malignancies

Celiac disease (CeD) is a chronic autoimmune disorder that is triggered by gluten in genetically susceptible individuals, and that is characterized by CeD-specific antibodies, HLA-DQ2 and/or HLA-DQ8 haplotypes, enteropathy and different clinical pictures related to many organs. Intestinal lymphoma may develop as a result of refractory CeD. If a patient diagnosed with CeD is symptomatic despite a strict gluten-free diet for at least 12 months, and does not improve with severe villous atrophy, refractory CeD can be considered present. The second of the two types of refractory CeD has abnormal monoclonal intraepithelial lymphocytes and can be considered as pre-lymphoma, and the next picture that will emerge is enteropathy-associated T-cell lymphoma. This manuscript addresses "CeD and malignancies" through a review of current literature and guidelines.

The seroprevalence of celiac disease in patients with symptoms of irritable bowel syndrome: A cross-sectional study in north of Iran

BACKGROUND

Celiac disease (CD) is a common cause of malabsorption that is definitively diagnosed by abnormal bowel biopsy, symptoms and histologic changes to gluten free diet. The symptoms of irritable bowel syndrome (IBS) are common in our community as the majority of people in Guilan, north of Iran, consume rice daily. Also, a number of celiac patients are unknown, and IBS are mistakenly diagnosed.

OBJECTIVE

This study aimed to evaluate the prevalence of CD among IBS patients.

METHODS

A total of 475 consecutive patients with IBS, confirmed by Rome IV, underwent celiac serological tests antitissue transglutaminase antibodies (IgA-tTG, IgG-tTG) after obtaining a written consent form. In case of positive serological tests, biopsy was performed from small intestine after endoscopyRESULTS: Thirty-one (6.53%, 95% CI: 4.55-9.22) patients were positive for celiac serology. Based on Marsh-Oberhuber criteria, out of 9 patients with positive pathology 77.78% (95% CI: 40.19-96.05) had marsh IIIc. In IBS patients cramp (0.009) and stomach fullness (0.021) were two statistically significant IBS symptoms.

CONCLUSIONS

We suggest physicians to consider celiac examinations for all patients with IBS symptoms, even for patients with no obvious celiac symptoms.

Co-factors, Microbes, and Immunogenetics in Celiac Disease to Guide Novel Approaches for Diagnosis and Treatment

Celiac disease (CeD) is a frequent immune-mediated disease that affects not only the small intestine but also many extraintestinal sites. The role of gluten proteins as dietary triggers, HLA-DQ2 or -DQ8 as major necessary genetic predisposition, and tissue transglutaminase (TG2) as mechanistically involved autoantigen, are unique features of CeD. Recent research implicates many cofactors working in synergism with these key triggers, including the intestinal microbiota and their metabolites, nongluten dietary triggers, intestinal barrier defects, novel immune cell phenotypes, and mediators and cytokines. In addition, apart from HLA-DQ2 and -DQ8, multiple and complex predisposing genetic factors and interactions have been defined, most of which overlap with predispositions in other, usually autoimmune, diseases that are linked to CeD. The resultant better understanding of CeD pathogenesis, and its manifold manifestations has already paved the way for novel therapeutic approaches beyond the lifelong strict gluten-free diet, which poses a burden to patients and often does not lead to complete mucosal healing. Thus, supported by improved mouse models for CeD and in vitro organoid cultures, several targeted therapies are in phase 2-3 clinical studies, such as highly effective gluten-degrading oral enzymes, inhibition of TG2, cytokine therapies, induction of tolerance to gluten ingestion, along with adjunctive and preventive approaches using beneficial probiotics and micronutrients. These developments are supported by novel noninvasive markers of CeD severity and activity that may be used as companion diagnostics, allow easy-to perform and reliable monitoring of patients, and finally support personalized therapy for CeD.

The expansion of CD14+ CD163+ subpopulation of monocytes and myeloid cells-associated cytokine imbalance; candidate diagnostic biomarkers for celiac disease (CD)

Celiac disease (CD) is a chronic autoimmune disorder of small intestine against dietary gluten, among genetically predisposed individuals. Monocytes are versatile innate immune cells involved in the regulation of inflammation, and strongly involved in the intestinal immunity. However, the role of monocytes and their subtypes in CD is not well demonstrated.

METHODS

Here, we assessed the polarization of CD14+ monocytes by evaluating the M1 (CD16) and M2 (CD163) markers by flowcytometry, their soluble forms (sCD16 and sCD163), and the serum levels of IL-10, IL-12, TGF-β, and TNF-α cytokines using ELISA method, among 30 CD patients and 30 sex- and age-matched healthy subjects (HS). We also analyzed the diagnostic values of all variables with significant differences.

RESULTS

CD14+CD163+ monocytes were more frequent in CD patients than HS, while CD14+CD16+ monocytes were higher in HS. IL-10and TNF-α increased, and TGF-β expression was decreased among CD patients. The sCD16 serum levels were elevated in patients, while sCD163 was higher but not significant among CD patients. CD163+/CD16+ and IL-10/IL-12 ratios were higher in CD patients, and TGFβ/TNFα ratio was higher in HS group. IL-10, CD14+CD163+, TNF-α, and IL-10/IL-12 ratios with the AUC over 0.7 were introduced as fair diagnostic markers. Our findings revealed that the M2 (CD14+CD163+) monocytes were more frequent among CD patients, and the cytokine balance was disturbed.

CONCLUSION

According to the significant functional diversities of monocyte subtypes between CD patients and HS group, these immunologic markers could be introduced as specific diagnostic biomarkers for CD.

Emergence of Celiac disease and Gluten-related disorders in Asia

Celiac disease (CeD) is a systemic, immune-mediated enteropathy, which is triggered by gluten protein in genetically susceptible individuals. CeD, once thought to be an uncommon disease, is now recognized to affect approximately 40-60 million people globally. While CeD is now well reported from a few Asian countries such as India, China, Pakistan, and Middle Eastern countries; it is still believed to be uncommon in the rest of Asia. Gluten-related diseases other than CeD, like non-celiac gluten sensitivity (NCGS) are also emerging globally. CeD and NCGS may present with either intestinal or extra-intestinal symptoms, and a proportion of them have overlapping symptoms with irritable bowel syndrome. Hence, many of them are misdiagnosed as having irritable bowel syndrome in clinical practice. In this review, we discuss the emergence of CeD and other gluten-related disorders, both globally and in Asia, the overlapping manifestations between gluten-related disorders and irritable bowel syndrome, and the challenges associated with diagnosis and management of CeD in Asia.

Spectrum of Clinical Presentation of Celiac Disease in Pediatric Population

Background

Classic form of celiac disease (CCD) presents with diarrhea and is traditionally taught as malabsorption syndrome. This form of CD is diagnosed with ease but non-classical form presenting without diarrhea is often missed and heavily underdiagnosed.

Objective

To determine the clinical spectrum of patients with CD.

Methods

This study was conducted in the Department of Gastroenterology & Hepatology at the Children’s Hospital, Lahore. Confirmed CD children according to NASPGHAN (North American Society of Pediatric Gastroenterology, Hepatology & Nutrition) criteria were enrolled in this study from June to September, 2020. Initial positivity followed by small bowel biopsy with Modified Marsh 2 and above is considered consistent with the diagnosis of CD.

Results

A total of 90 patients were selected according to NASPGHAN criteria, 77 (85.6%) patients had CCD whereas 13 (14.4%) patients had non-classical CD (NCCD). The mean ± SD age at diagnosis of CCD was 2.6 ± 2.3 years whereas mean ± SD in NCCD was 9 ± 1.8 years. Females clearly predominate in our cohort in general. Chronic diarrhea followed by failure to thrive (85%) were the most common symptoms in CCD whereas short stature (69%) was the most frequent feature in NCCD. Among CD patients, tissue transglutaminase-​immunoglobulin A (TTG-IgA) titre was significantly high (>10 times) in 80% of CD patients and the rest had positivity but not up to 10 times. There was no significant difference in titre of anti-TTG between CCD and NCCD.

Conclusion

Classical CD is still the most common in developing countries like Pakistan. High index of suspicion of CD should be maintained for patients who present with short stature, recurrent abdominal pain and refractory anemia.

Human leukocyte antigen (HLA)-DQ2 and -DQ8 haplotypes in celiac, celiac with type 1 diabetic, and celiac suspected pediatric cases

Celiac disease (CD) is an autoimmune enteropathy triggered by ingestion of gluten present in wheat, barley, and rye. Gluten along with environmental trigger starts an inflammatory reaction which results in damage to small intestine. Human leukocyte antigen (HLA)-DQA1∗05, -DQB1∗02, and -DQB1∗03:02 are the known risk alleles of CD. The diagnostic method for CD involves serological or intestinal biopsy, but genetic test could be implemented. HLA typing precludes the need for further diagnosis and it has high negative predictive value. The aim of this study was to make aware of HLA molecular typing for celiac disease among local laboratories and healthcare professionals. The prevalence and frequency distribution of HLA-DQ2 and -DQ8 haplotypes in 175 pediatric unrelated healthy controls, celiac patients, and CD with concurrent diabetes mellitus type 1 (DM1) was evaluated. The most common haplotype was DQ2 followed by DQ8. In control group only DQ2 was observed with frequency of 8.5%. In celiac patients 85.7% were DQ2, 11.4% were DQ8, and rest were DQ2/DQ8 (2.8%), and all had CD. In the group of CD with DM1, 31.4% had DQ2, 25% had DQ8, and 34% having both the haplotypes; while only 9 of these patients were suffering from CD. It was concluded that Celiac disease is frequently unrecognized by physicians, in part because of its variable clinical presentation and symptoms. Thus genetic testing for celiac disease could be an additive tool for diagnosis to exclude ambiguity.

The prevalence of celiac disease in Saudi patients with type 1 diabetes mellitus

BACKGROUND

Celiac disease (CD) is an autoimmune disease that is highly associated with type 1 diabetes mellitus (T1DM). The reported prevalence of CD in patients with T1DM in Saudi Arabia varies and the number of studies is limited.

OBJECTIVES

Determine the prevalence of CD diagnosed with anti-tissue transglutaminase (anti-tTG) antibodies or by endoscopic biopsy in adolescents and adults with T1DM.

DESIGN

Cross-sectional, retrospective medical record review.

SETTING

Tertiary care center.

PATIENTS AND METHODS

The study population included adolescents and adults with T1DM who were screened for CD between 2010 and 2019. The study variables included age, sex, age at diagnosis of T1DM, age of positive celiac screening, glycated hemoglobin (HbA1c), total daily insulin dose, frequency of diabetic ketoacidosis (DKA) and other autoimmune diseases.

MAIN OUTCOME MEASURES

The prevalence of celiac disease in adolescents and adults with T1DM.

SAMPLE SIZE

539 patients.

RESULTS

The prevalence of positive celiac test results was 11.5% (n=62). A small proportion (n=5, 8%) of the positive CD group was diagnosed with T1DM after they tested positive with the celiac screening test. Ten (16%) were diagnosed with T1DM and CD in the same year. The rest of the sample had a positive screening test after being diagnosed with T1DM. There was no statistically significant difference between the CD positive and negative groups for HbA1C, DKA frequency, microvascular complications of diabetes or thyroid disorder. For histopathological confirmation of CD, only 37% (n=23) of the group with a positive screening test underwent endoscopy. In this group, 43% (n=10) had normal endoscopic biopsy findings, 21.7% (n=5) had partial villous atrophy and 34.7% (n=8) had total villous atrophy.

CONCLUSIONS

This study highlights the importance of screening for CD in T1DM patients. CD prevalence is high in patients with T1DM, despite the high likelihood of underdiagnosis. Additional studies of different age groups and the use of different study methods are required. In addition, a unified national strategy to diagnose CD in T1DM patients is highly advisable.

LIMITATIONS

Retrospective, single-center, few confirmations of CD by intestinal biopsy.

CONFLICT OF INTEREST

None.

High-resolution genotyping indicates that children with type 1 diabetes and celiac disease share three HLA class II loci in DRB3, DRB4 and DRB5 genes

Type 1 diabetes (T1D) and celiac disease (CD) share common genetic loci, mainly within the human leukocyte antigen (HLA) class II complex. Extended genotyping of HLA class II alleles and their potential risk for developing both diseases remains to be studied. The present study compared extended HLA-class II gene polymorphisms in children with T1D, CD, and a subgroup diagnosed with both diseases (T1D w/CD). Next-generation targeted sequencing (NGTS) of HLA-DRB3, DRB4, DRB5, DRB1, DQA1, DQB1, DPA1, and DPB1 alleles from DNA collected from 68 T1D, 219 CD, and seven T1D w/CD patients were compared with 636 HLA-genotyped Swedish children from the general population selected as controls. In comparison to controls, the DRB4*01:03:01 allele occurred more frequently in T1D w/CD (odds ratio (OR) = 7.84; 95% confidence interval (95% CI) = (2.24, 34.5), P = 0.0002) and T1D (OR = 3.86; 95% CI, (2.69, 5.55), P = 1.07 × 10^-14 ), respectively. The DRB3*01:01:02 allele occurred more frequently in CD as compared to controls (OR = 7.87; 95% CI, (6.17, 10.03), P = 4.24 × 10^-71 ), but less frequently in T1D (OR = 2.59; 95% CI, (1.76, 3.81), P = 7.29 × 10^-07 ) and T1D w/CD (OR = 0.87; 95% CI, (0.09, 3.96), P ≤ 0.999). The frequency of the DRB4*01:03:01-DRB1*04:01:01-DQA1*03:01:01-DQB1*03:02:01 (DR4-DQ8) haplotype was higher in T1D w/CD (OR = 12.88; 95% CI (4.35, 38.14) P = 3.75 × 10^-9 ), and moderately higher in T1D (OR = 2.13; 95% CI (1.18, 3.83) P = 0.01) compared with controls, but comparable in CD (OR = 1.45; 95% CI (0.94, 2.21), P = 0.08) and controls. Children with T1D and CD are associated with DRB4*01:03:01, DRB3*01:01:02, and DRB3*02:02:01 of which DRB4*01:03:01 confers the strongest risk allele for developing T1D w/CD.

Microbial transglutaminase: A biotechnological tool to manage gluten intolerance

Celiac disease (CD) is a chronic immune-mediated disease in which gluten ingestion leads to damage of the small intestinal mucosa in genetically susceptible individuals. The enteropathy is mainly induced by the production of IFN-γ from intestinal CD4⁺T cells that recognise gliadin peptides following deamidation by tissue transglutaminase. The only available therapy is a strict, lifelong gluten-free diet (GFD). This diet is strongly demanding for patients, which justifies the search for alternative strategies. The enzyme approach is one promising strategy to address this issue. In particular, transamidation of wheat gliadin by microbial transglutaminase (mTG) was fully effective at inhibiting gliadin-specific IFN-γ secretion in intestinal T cells from CD patients. Furthermore, transamidated gliadin induced higher levels of the anti-inflammatory IL-10 than native gliadin in different in vitro models. These data suggest that a more balanced immune response could be induced by mTG-treated gliadin in the small intestine of celiac patients. Furthermore, the highlighted biological property of mTG-treated gliadin could be exploited to induce tolerance to native gliadin in at-risk individuals.

Diagnosing coeliac disease: Out with the old and in with the new?

Coeliac disease (CD) is a complex condition resulting from an interplay between genetic and environmental factors. When diagnosing the condition, serological testing and genotyping are useful in excluding CD, although the gold standard of testing is currently histopathological examination of the small intestine. There are drawbacks associated with this form of testing however and because of this, novel forms of testing are currently under investigation. Before we develop completely novel tests though, it is important to ask whether or not we can simply use the data we gather from coeliac patients more effectively and build a more accurate snapshot of CD through statistical analysis of combined metrics. It is clear that not one single test can accurately diagnose CD and it is also clear that CD patients can no longer be defined by discrete classifications, the continuum of patient presentation needs to be recognised and correctly captured to improve diagnostic accuracy. This review will discuss the current diagnostics for CD and then outline novel diagnostics under investigation for the condition. Finally, improvements to current protocols will be discussed with the need for a holistic "snapshot" of CD using a number of metrics simultaneously.

Stimulatory Response of Celiac Disease Peripheral Blood Mononuclear Cells Induced by RNAi Wheat Lines Differing in Grain Protein Composition

Wheat gluten proteins are responsible for the bread-making properties of the dough but also for triggering important gastrointestinal disorders. Celiac disease (CD) affects approximately 1% of the population in Western countries. The only treatment available is the strict avoidance of gluten in the diet. Interference RNA (RNAi) is an excellent approach for the down-regulation of genes coding for immunogenic proteins related to celiac disease, providing an alternative for the development of cereals suitable for CD patients. In the present work, we report a comparative study of the stimulatory capacity of seven low-gluten RNAi lines differing in grain gluten and non-gluten protein composition, relevant for CD and other gluten pathologies. Peripheral blood mononuclear cells (PBMCs) of 35 patients with active CD were included in this study to assess the stimulatory response induced by protein extracts from the RNAi lines. Analysis of the proliferative response and interferon-gamma (INF-γ) release of PBMCs demonstrated impaired stimulation in response to all RNAi lines. The lower response was provided by lines with a very low content of α- and γ-gliadins, and low or almost devoid of DQ2.5 and p31-43 α-gliadin epitopes. The non-gluten protein seems not to play a key role in PBMC stimulation.

The pathogenic role of autoantibodies in recurrent pregnancy loss

In the present manuscript, we review the recent research investigating the pathogenic association between most studied autoantibodies and recurrent pregnancy loss. Pregnancy loss represents a common obstetric complication occurring in about 15%-25% of all clinically recognized pregnancies. The recurrence of pregnancy loss identifies a distinct clinical entity, that is recurrent pregnancy loss (RPL), affecting about 2%-4% of couples. Several factors, including age, chromosomal abnormalities, uterine anomalies, thrombophilic disorders, endocrinopathies, hormonal and metabolic disorders, infections, sperm quality, and lifestyle issues, are involved in RPL. The role of autoantibodies in RPL is only partially determined. In some cases (antiphospholipid antibodies [aPL]), their involvement is well established. In other cases (anti-thyroid autoantibodies, antinuclear, anti-transglutaminase, and anti-endomysial antibodies), it is still debated, despite multiple, although not fully conclusive, evidences strongly suggest a possible involvement in RPL. Further extensive research is needed to definitively confirm or exclude their actual role.

Association of Gluten Intake During the First 5 Years of Life With Incidence of Celiac Disease Autoimmunity and Celiac Disease Among Children at Increased Risk

IMPORTANCE

High gluten intake during childhood may confer risk of celiac disease.

OBJECTIVES

To investigate if the amount of gluten intake is associated with celiac disease autoimmunity and celiac disease in genetically at-risk children.

DESIGN, SETTING, AND PARTICIPANTS

The participants in The Environmental Determinants of Diabetes in the Young (TEDDY), a prospective observational birth cohort study designed to identify environmental triggers of type 1 diabetes and celiac disease, were followed up at 6 clinical centers in Finland, Germany, Sweden, and the United States. Between 2004 and 2010, 8676 newborns carrying HLA antigen genotypes associated with type 1 diabetes and celiac disease were enrolled. Screening for celiac disease with tissue transglutaminase autoantibodies was performed annually in 6757 children from the age of 2 years. Data on gluten intake were available in 6605 children (98%) by September 30, 2017.

EXPOSURES

Gluten intake was estimated from 3-day food records collected at ages 6, 9, and 12 months and biannually thereafter until the age of 5 years.

MAIN OUTCOMES AND MEASURES

The primary outcome was celiac disease autoimmunity, defined as positive tissue transglutaminase autoantibodies found in 2 consecutive serum samples. The secondary outcome was celiac disease confirmed by intestinal biopsy or persistently high tissue transglutaminase autoantibody levels.

RESULTS

Of the 6605 children (49% females; median follow-up: 9.0 years [interquartile range, 8.0-10.0 years]), 1216 (18%) developed celiac disease autoimmunity and 447 (7%) developed celiac disease. The incidence for both outcomes peaked at the age of 2 to 3 years. Daily gluten intake was associated with higher risk of celiac disease autoimmunity for every 1-g/d increase in gluten consumption (hazard ratio [HR], 1.30 [95% CI, 1.22-1.38]; absolute risk by the age of 3 years if the reference amount of gluten was consumed, 28.1%; absolute risk if gluten intake was 1-g/d higher than the reference amount, 34.2%; absolute risk difference, 6.1% [95% CI, 4.5%-7.7%]). Daily gluten intake was associated with higher risk of celiac disease for every 1-g/d increase in gluten consumption (HR, 1.50 [95% CI, 1.35-1.66]; absolute risk by age of 3 years if the reference amount of gluten was consumed, 20.7%; absolute risk if gluten intake was 1-g/d higher than the reference amount, 27.9%; absolute risk difference, 7.2% [95% CI, 6.1%-8.3%]).

CONCLUSIONS AND RELEVANCE

Higher gluten intake during the first 5 years of life was associated with increased risk of celiac disease autoimmunity and celiac disease among genetically predisposed children.

Is the double gene dose of DQ2.5 or DQ2.5/DQ2.2 an involved factor in the clinical features of celiac disease?

Objectives: Celiac disease (CD) is barely known if the quantitative effect of DQB1*02 (DQ2) double dose in antigen presentation to T-cells has translation into the clinic. For this, we have conducted a case-control study in a cohort of two hundred and nineteen patients with CD. Material and methods: For the control group, individuals were enrolled with single dose of DQ2, carrying DQ2.5 heterodimers in heterozygous state (n = 109). The cases with CD were diving into three groups: cases with overall DQ2 double dose (n = 110), DQ2.5 homozygous (n = 33) and DQ2.5/DQ2.2 heterozygous (n = 77). Prevalence and associations of demographic, laboratory, histological and clinical characteristics between the control group and cases were studied. Results: No differences were found for the total of 16 variables analyzed between the control group and overall DQ2 double dose as well as DQ2.5 homozygous cases. In contrast to DQ2.5/DQ2.2, heterozygous cases presented a protection factor for developing allergy to airway allergens regarding the control group (OR = 0.210, p = .019). Conclusions: To date, this negative association has not been described. Further studies will be necessary to elucidate the implication of this protection factor in CD. Since, until now the association between CD and allergic diseases has been poorly studied.

Celiac disease: a comprehensive current review

BACKGROUND

Celiac disease remains a challenging condition because of a steady increase in knowledge tackling its pathophysiology, diagnosis, management, and possible therapeutic options.

MAIN BODY

A major milestone in the history of celiac disease was the identification of tissue transglutaminase as the autoantigen, thereby confirming the autoimmune nature of this disorder. A genetic background (HLA-DQ2/DQ8 positivity and non-HLA genes) is a mandatory determinant of the development of the disease, which occurs with the contribution of environmental factors (e.g., viral infections and dysbiosis of gut microbiota). Its prevalence in the general population is of approximately 1%, with female predominance. The disease can occur at any age, with a variety of symptoms/manifestations. This multifaceted clinical presentation leads to several phenotypes, i.e., gastrointestinal, extraintestinal, subclinical, potential, seronegative, non-responsive, and refractory. Although small intestinal biopsy remains the diagnostic 'gold standard', highly sensitive and specific serological tests, such as tissue transglutaminase, endomysial and deamidated gliadin peptide antibodies, have become gradually more important in the diagnostic work-up of celiac disease. Currently, the only treatment for celiac disease is a life-long, strict gluten-free diet leading to improvement in quality of life, ameliorating symptoms, and preventing the occurrence of refractory celiac disease, ulcerative jejunoileitis, and small intestinal adenocarcinoma and lymphoma.

CONCLUSIONS

The present review is timely and provides a thorough appraisal of various aspects characterizing celiac disease. Remaining challenges include obtaining a better understanding of still-unclear phenotypes such as slow-responsive, potential (minimal lesions) and seronegative celiac disease. The identification of alternative or complementary treatments to the gluten-free diet brings hope for patients unavoidably burdened by diet restrictions.

Reovirus: Friend and Foe

Purpose of Review

Mammalian orthoreovirus (reovirus) is a powerful tool for studying viral replication and pathogenesis. Most reovirus infections are subclinical, however recent work has catapulted reovirus into the clinical spotlight.

Recent Findings

Owing to its capacity to kill cancer cells more efficiently than normal cells, reovirus is under development as a therapeutic for a variety of cancers. New efforts have focused on genetically engineering reovirus to increase its oncolytic capacity, and determining how reovirus potentiates immunotherapy. Other recent studies highlight a potential role for reovirus in celiac disease (CeD). Using mouse models of CeD, reovirus caused loss of oral tolerance to dietary antigens, opening the possibility that reovirus could trigger CeD in humans.

Summary

We will focus on new developments in reovirus oncolysis and studies suggesting a role for reovirus as a trigger for celiac disease (CeD) that make reovirus a potential friend and foe to human health.

The Gut-Renal Connection in IgA Nephropathy

The connection between a dysregulated gut-associated lymphoid tissue and IgA nephropathy (IgAN) was supposed decades ago after the observation of increased association of IgAN with celiac disease. Pivotal studies have shown a role for alimentary antigens, particularly gliadin in developing IgAN in BALB/c mice, and a reduction in IgA antigliadin antibodies and proteinuria was reported after gluten free-diet in patients with IgAN. Recently a genome-wide association study showed that most loci associated with IgAN also are associated with immune-mediated inflammatory bowel diseases, maintenance of the intestinal barrier, and response to gut pathogens. Transgenic mice that overexpress the B-cell activating factor develop hyper-IgA with IgAN modulated by alimentary components and intestinal microbiota. Mice expressing human IgA1 and a soluble form of the IgA receptor (sCD89) develop IgAN, which is regulated by dietary gluten. Recent observations have confirmed gut-associated lymphoid tissue hyper-reactivity in IgAN patients with IgA against alimentary components. Interesting results were provided by the NEFIGAN randomized controlled trial, which adopted an enteric controlled-release formulation of the corticosteroid budesonide targeted to Peyer's patches. After 9 months of treatment, a reduction in proteinuria was observed with stabilized renal function and limited adverse events. The gut-renal connection is an area of promising new treatment approaches for patients with IgAN.

HLA-DQ2 homozygosis increases tTGA levels at diagnosis but does not influence the clinical phenotype of coeliac disease: A multicentre study

BACKGROUND AND PURPOSE

Magnitude of gluten-specific T-cell responses in coeliac disease (CD) might be dependent on HLA-DQ2 gene dose. We aimed to investigate the effects of HLA-DQB1*02 allele dose on clinical outcomes.

METHODS

We reviewed the charts of all coeliac patients attending to three Hungarian university clinics after 1997 and included those patients, who (a) were diagnosed with CD, (b) underwent high-resolution HLA typing and (c) were ≥18 years at the time of data collection. HLA typing was performed to determine DQB1*02 allele dose. Patients were divided into risk groups by DQB1*02 allele dose, as follows: high-, intermediate- and low-risk groups corresponded to a double, single and zero doses, respectively. We used ANOVA and Pearson's chi-squared test to explore association between HLA risk and clinical variables.

RESULTS

A total of 727 coeliac patients attended the clinics but only 105 (14.4%) patients were eligible for inclusion. High, intermediate and low HLA risk patients comprised 35.3%, 52.3% and 12.3% of the study population, respectively. Double dose of HLA-DQB1*02 was more frequent in patient with high tTGA level (>10 times the upper limit of normal; p = 0.045). Gene dose was not associated with younger age at diagnosis (p = 0.549), gender (p = 0.739), more severe diagnostic histology (p = 0.318), more frequent classical presentation (p = 0.846), anaemia (p = 0.611), metabolic bone disease (p = 0.374), dermatitis herpetiformis (p = 0.381) and autoimmune diseases (p = 0.837).

CONCLUSIONS

Our study shows a significant gene dose effect in terms of tTGA level at diagnosis, but no significant association between HLA-DQB1*02 allele dose and the clinical outcomes in CD.

T lymphocytes in the intestinal mucosa: defense and tolerance

Although lymphocytes are known to circulate throughout lymphoid tissues and blood, they also establish residency in nonlymphoid organs, most prominently in barrier tissues, such as the intestines. The adaptation of T lymphocytes to intestinal environments requires constant discrimination between natural stimulation from commensal flora and food and pathogens that need to be cleared. Genetic variations that cause a defective defense or a break in tolerance along with environmental cues, such as infection or imbalances in the gut microbiota known as dysbiosis, can trigger several immune disorders via the activation of T lymphocytes in the intestines. Elucidation of the immune mechanisms that distinguish between commensal flora and pathogenic organisms may reveal therapeutic targets for the prevention or modulation of inflammatory diseases and boost the efficacy of cancer immunotherapy. In this review, we discuss the development and adaptation of T lymphocytes in the intestine, how these cells protect the host against pathogenic infections while tolerating food antigens and commensal microbiota, and the potential implications of targeting these cells for disease management and therapeutics.

Classical celiac disease is more frequent with a double dose of HLA-DQB1*02: A systematic review with meta-analysis

BACKGROUND AND AIMS

Experimental data suggest that the HLA-DQ2 gene dose has a strong quantitative effect on clinical outcomes and severity of celiac disease (CD). We aimed to conduct a meta-analysis with systematic review to investigate the association between HLA-DQB1*02 gene doses and the characteristics of CD.

METHODS

We searched seven medical databases for studies discussing HLA-DQB1 gene dose in CD and various disease characteristics, such as clinical presentation, histology, age at diagnosis, and comorbidities. Odds ratios (OR, for categorical variables) and weighted mean differences (for age) were calculated to compare patients with a double dose of HLA-DQB1*02 versus those with single and zero doses. Heterogeneity was tested with I2-statistics and explored by study subgroups (children and adults).

RESULTS

Twenty-four publications were eligible for meta-analysis. Classical CD was more frequent with a double versus single dose of the HLA-DQB1*02 allele (OR = 1.758, 95%CI: 1.148-2.692, I2 = 0.0%). In pediatric studies, gene dose effect was more prominent (OR = 2.082, 95%CI: 1.189-3.646, I2 = 0.0% and OR = 3.139, 95%CI: 1.142-8.630, I2 = 0.0% for the comparisons of double versus single and double versus zero dose, respectively). Atrophic histology was more prevalent with a double versus zero dose (OR = 2.626, CI: 1.060-6.505, I2 = 21.3%). We observed no gene dose effect regarding diarrhea, age at diagnosis, the severity of villous atrophy, and the association with type 1 diabetes mellitus.

CONCLUSION

A double dose of HLA-DQB1*02 gene seems to predispose patients to developing classical CD and villous atrophy. Risk stratification by HLA-DQB1*02 gene dose requires further clarification due to the limited available evidence.

Murine Norovirus Infection Induces TH1 Inflammatory Responses to Dietary Antigens

Intestinal reovirus infection can trigger T helper 1 (TH1) immunity to dietary antigen, raising the question of whether other viruses can have a similar impact. Here we show that the acute CW3 strain of murine norovirus, but not the persistent CR6 strain, induces TH1 immunity to dietary antigen. This property of CW3 is dependent on its major capsid protein, a virulence determinant. Transcriptional profiling of mesenteric lymph nodes following infection reveals an immunopathological signature that does not segregate with protective immunity but with loss of oral tolerance, in which interferon regulatory factor 1 is critical. These data show that viral capacity to trigger specific inflammatory pathways at sites where T cell responses to dietary antigens take place interferes with the development of tolerance to an oral antigen. Collectively, these data provide a foundation for the development of therapeutic strategies to prevent TH1-mediated complex immune disorders triggered by viral infections.

Human intraepithelial lymphocytes

The location of intraepithelial lymphocytes (IEL) between epithelial cells, their effector memory, cytolytic and inflammatory phenotype positions them to kill infected epithelial cells and protect the intestine against pathogens. Human TCRαβ+CD8αβ+ IEL have the dual capacity to recognize modified self via natural killer (NK) receptors (autoreactivity) as well as foreign antigen via the T cell receptor (TCR), which is accomplished in mouse by two cell subsets, the naturally occurring TCRαβ+CD8αα+ and adaptively induced TCRαβ+CD8αβ+ IEL subsets, respectively. The private/oligoclonal nature of the TCR repertoire of both human and mouse IEL suggests local environmental factors dictate the specificity of IEL responses. The line between sensing of foreign antigens and autoreactivity is blurred for IEL in celiac disease, where recognition of stress ligands by induced activating NK receptors in conjunction with inflammatory signals such as IL-15 can result in low-affinity TCR/non-cognate antigen and NK receptor/stress ligand interactions triggering destruction of intestinal epithelial cells.

Medical relevance of protein-truncating variants across 337,205 individuals in the UK Biobank study

Protein-truncating variants can have profound effects on gene function and are critical for clinical genome interpretation and generating therapeutic hypotheses, but their relevance to medical phenotypes has not been systematically assessed. Here, we characterize the effect of 18,228 protein-truncating variants across 135 phenotypes from the UK Biobank and find 27 associations between medical phenotypes and protein-truncating variants in genes outside the major histocompatibility complex. We perform phenome-wide analyses and directly measure the effect in homozygous carriers, commonly referred to as “human knockouts,” across medical phenotypes for genes implicated as being protective against disease or associated with at least one phenotype in our study. We find several genes with strong pleiotropic or non-additive effects. Our results illustrate the importance of protein-truncating variants in a variety of diseases.

Protein-truncating variants (PTVs) are predicted to significantly affect a gene’s function and, thus, human traits. Here, DeBoever et al. systematically analyze PTVs in more than 300,000 individuals across 135 phenotypes and identify 27 associations between PTVs and medical conditions.

Risk variation in celiac disease in a population from Southern Spain: evaluating the influence of the DQB1*02:02 allele frequency

OBJECTIVES

To date, the greatest genetic risk factor known for celiac disease (CD) is the presence of HLA-DQ2 heterodimers, specifically DQ2.5 in state of homozygosis or heterozygosis. DQ2.2 variants are the second most important risk factor when carried trans to DQ2. This study aimed to determine the prevalence and risk genotypes of HLA-DR-DQ.

MATERIAL AND METHODS

A total of 196 patients with CD and 206 healthy controls from the Province of Málaga (southern Spain) were included. The corresponding risk gradient in our population was established in accordance with the odds ratios (ORs) found.

RESULTS

The heterozygous genotype for DR7-DQ2.2/DR3-DQ2.5 presented the highest risk (OR =6.404, p = .0001) followed by the DR3-DQ2.5 homozygous genotype (OR =4.721, p = .001). An intermediate risk was found for the DQ2.5 heterozygous genotype with no other DQ risk variant (DQ8 or DQ2.2). Similarly, these three genotypes had also an increase in the risk of associated-autoimmune diseases. The DQB1*02:01 allele was the most widely represented among patients with CD respect to the control group (f = 0.479, p = .0001), with the second most common being DQB1*02:02 (f = 0.209, p = .0001).

CONCLUSIONS

In addition to the gene dosage effect confirmed in our report, and in contrast with previous studies, we found a raised risk for those patients with DQ2.2 heterodimers in trans configuration to DQ2.5 compared to DQ2.5 homozygous individuals. Therefore, in our population of patients with CD the frequency of DQ2.2 acts as a factor that increases the genetic risk of developing CD.

HLA-DQ genetics in children with celiac disease: a meta-analysis suggesting a two-step genetic screening procedure starting with HLA-DQ β chains

BackgroundSpecific HLA-DQ genes have been recognized as necessary - but not sufficient - factors for the occurrence of Celiac Disease (CD). Through a meta-analysis, evaluating the distribution of CD-related HLA genotypes in children, we aimed at providing insights for a potential widened screening strategy.MethodsAfter a systematic search on the association between class II HLA genes and CD in children, 46 publications were obtained and assessed for eligibility. A total of 13 eligible studies were submitted to data extraction and analysis (10 case-control studies and 3 cohort studies). Case-control studies collectively enrolled 740 CD patients and 943 controls.ResultsIn the population-stratified analysis, the following alleles conferred a significantly increased risk for CD: HLA-DQB1*02 (odds ratio [OR]=10.28) and HLA-DQB1*03:02 (OR=2.24). By drafting a risk gradient to develop CD according to HLA genetic background, the highest risk is confirmed to exist for DQ2/DQ2 homozygous subjects, regardless of the ethnicities (OR=5.4). Actually, the genotype DQ2/β2 showed basically the same risk (OR=5.3). Indeed, no differences have been found in CD risk between DQ2/β2 and DQ2/DQ2, as well as between DQ8/β2 and DQ2/DQ8, and between β2/DQX and DQ2/X.ConclusionThe HLA-DQB1*02:01 allele is present in more than 90% CD children. In the perspective of a widened pediatric population screening for CD, a double-step process might be suggested: HLA-DQB1*02:01 might be investigated first and, only if this result is positive, children might be candidate for a prospective serologic screening, as a second step.

The gut-kidney axis in IgA nephropathy: role of microbiota and diet on genetic predisposition

Recent data suggest that gut-associated lymphoid tissue (GALT) plays a major role in the development of immunoglobulin A (IgA) nephropathy (IgAN). A genome-wide association study showed that most loci associated with the risk of IgAN are also associated with immune-mediated inflammatory bowel diseases, maintenance of the intestinal barrier and regulation of response to gut pathogens. Studies involving experimental models have demonstrated a pivotal role of intestinal microbiota in the development of IgAN in mice producing high levels of IgA and in transgenic mice overexpressing BAFF, a B-cell factor crucial for IgA synthesis, indicating the role of genetic background, B-cell activity, GALT intestinal immunity and diet. The effect of diet was suggested by pilot studies carried out 30 years ago which showed that a gluten-rich diet induced IgAN in mice and that some patients benefited from a gluten-free diet. A recent experimental model in mice expressing human IgA1 and Fc alpha receptor CD89 reported clinical and histological improvement after a gluten-free diet. Clinical observations have elicited new interest in GALT hyper-reactivity in IgAN patients. In a pilot study, a reduction in proteinuria was attained using an enteric controlled-release formulation of the corticosteroid budesonide targeted to the Peyer's patches at the ileocecal junction. This formulation was tested in the placebo-controlled NEFIGAN phase 2b trial, with a reduction in proteinuria after 9 months of treatment together with stabilization of renal function in patients with persistent proteinuria. In conclusion, the gut-kidney axis modulated by microbiota and diet is a promising target for focused treatment of IgAN in genetically predisposed patients at risk of progression.

Intestinal epithelium, intraepithelial lymphocytes and the gut microbiota - Key players in the pathogenesis of celiac disease

Celiac disease (CD) is a chronic immune-mediated disorder triggered by the ingestion of gluten in genetically predisposed individuals. Before activating the immune system, gluten peptides are transferred by the epithelial barrier to the mucosal lamina propria, where they are deamidated by intestinal tissue transglutaminase 2. As a result, they strongly bind to human leucocyte antigens (HLAs), especially HLA-DQ2 and HLA-DQ8, expressed on antigen-presenting cells. This induces an inflammatory response, which results in small bowel enteropathy. Although gluten is the main external trigger activating both innate and adaptive (specific) immunity, its presence in the intestinal lumen does not fully explain CD pathogenesis. It has been hypothesized that an early disruption of the gut barrier in genetically susceptible individuals, which would result in an increased intestinal permeability, could precede the onset of gluten-induced immune events. The intestinal barrier is a complex functional structure, whose functioning is dependent on intestinal microbiota homeostasis, epithelial layer integrity, and the gut-associated lymphoid tissue with its intraepithelial lymphocytes (IELs). The aim of this paper was to review the current literature and summarize the role of the gut microbiota, epithelial cells and their intercellular junctions, and IELs in CD development.

Reovirus infection triggers inflammatory responses to dietary antigens and development of celiac disease

Viral infections have been proposed to elicit pathological processes leading to the initiation of T helper 1 (TH1) immunity against dietary gluten and celiac disease (CeD). To test this hypothesis and gain insights into mechanisms underlying virus-induced loss of tolerance to dietary antigens, we developed a viral infection model that makes use of two reovirus strains that infect the intestine but differ in their immunopathological outcomes. Reovirus is an avirulent pathogen that elicits protective immunity, but we discovered that it can nonetheless disrupt intestinal immune homeostasis at inductive and effector sites of oral tolerance by suppressing peripheral regulatory T cell (pTreg) conversion and promoting TH1 immunity to dietary antigen. Initiation of TH1 immunity to dietary antigen was dependent on interferon regulatory factor 1 and dissociated from suppression of pTreg conversion, which was mediated by type-1 interferon. Last, our study in humans supports a role for infection with reovirus, a seemingly innocuous virus, in triggering the development of CeD.

Physiopathology and Management of Gluten-Induced Celiac Disease

Proline- and glutamine-rich gluten proteins are one of the major constituents of cereal dietary proteins, which are largely resistant to complete cleavage by the human gastrointestinal (GI) digestive enzymes. Partial digestion of gluten generates approximately 35 amino acids (aa) immunomodulatory peptides which activate T-cell-mediated immune system, followed by immunological inflammation of mucosa leading to the onset of celiac disease (CD). CD is an autoimmune disease associated with HLA-DQ2/DQ8 polymorphism and dysbiosis of gut microbiota. CD is either diagnosed using duodenal mucosal biopsis or serological testing for transglutaminase 2 (TG2) specific antibodies (IgA and IgG). Current therapy for CD management is gluten-free diet, while other therapies like glutenase, probiotics, immunomodulation, jamming of HLA-DQ2, inhibition of TG2, and gluten tolerance aided by gluten tolerizing vaccines are being developed.

Comparison of four functionalization methods of gold nanoparticles for enhancing the enzyme-linked immunosorbent assay (ELISA)

The enzyme-linked immunosorbent assay (ELISA) technique is based on the specific recognition ability of the molecular structure of an antigen (epitope) by an antibody and is likely the most important diagnostic technique used today in bioscience. With this methodology, it is possible to diagnose illness, allergies, alimentary fraud, and even to detect small molecules such as toxins, pesticides, heavy metals, etc. For this reason, any procedures that improve the detection limit, sensitivity or reduce the analysis time could have an important impact in several fields. In this respect, many methods have been developed for improving the technique, ranging from fluorescence substrates to methods for increasing the number of enzyme molecules involved in the detection such as the biotin-streptavidin method. In this context, nanotechnology has offered a significant number of proposed solutions, mainly based on the functionalization of nanoparticles from gold to carbon which could be used as antibody carriers as well as reporter enzymes like peroxidase. However, few works have focused on the study of best practices for nanoparticle functionalization for ELISA enhancement. In this work, we use 20 nm gold nanoparticles (AuNPs) as a vehicle for secondary antibodies and peroxidase (HRP). The design of experiments technique (DOE) and four different methods for biomolecule loading were compared using a rabbit IgG/goat anti-rabbit IgG ELISA model (adsorption, directional, covalent and a combination thereof). As a result, AuNP probes prepared by direct adsorption were the most effective method. AuNPs probes were then used to detect gliadin, one of the main components of wheat gluten, the protein composite that causes celiac disease. With this optimized approach, our data showed a sensitivity increase of at least five times and a lower detection limit with respect to a standard ELISA of at least three times. Additionally, the assay time was remarkably decreased.

Involvement of cell surface TG2 in the aggregation of K562 cells triggered by gluten

Gluten-induced aggregation of K562 cells represents an in vitro model reproducing the early steps occurring in the small bowel of celiac patients exposed to gliadin. Despite the clear involvement of TG2 in the activation of the antigen-presenting cells, it is not yet clear in which compartment it occurs. Herein we study the calcium-dependent aggregation of these cells, using either cell-permeable or cell-impermeable TG2 inhibitors. Gluten induces efficient aggregation when calcium is absent in the extracellular environment, while TG2 inhibitors do not restore the full aggregating potential of gluten in the presence of calcium. These findings suggest that TG2 activity is not essential in the cellular aggregation mechanism. We demonstrate that gluten contacts the cells and provokes their aggregation through a mechanism involving the A-gliadin peptide 31-43. This peptide also activates the cell surface associated extracellular TG2 in the absence of calcium. Using a bioinformatics approach, we identify the possible docking sites of this peptide on the open and closed TG2 structures. Peptide docks with the closed TG2 structure near to the GTP/GDP site, by establishing molecular interactions with the same amino acids involved in stabilization of GTP binding. We suggest that it may occur through the displacement of GTP, switching the TG2 structure from the closed to the active open conformation. Furthermore, docking analysis shows peptide binding with the β-sandwich domain of the closed TG2 structure, suggesting that this region could be responsible for the different aggregating effects of gluten shown in the presence or absence of calcium. We deduce from these data a possible mechanism of action by which gluten makes contact with the cell surface, which could have possible implications in the celiac disease onset.

Improving outcomes of refractory celiac disease - current and emerging treatment strategies

Intestinal inflammation and symptoms of celiac disease (CD) usually respond well to gluten withdrawal, but rare cases are refractory to diet. Two types of refractory CD are discriminated on the basis of the presence or absence of an atypical population of mucosal lymphocytes that may progress to enteropathy-associated T-cell lymphoma. Challenges remain in the secure diagnosis of both types of refractory disease, and evidence on which to base treatment recommendations is flawed by the small numbers of reported patients and the use of different diagnostic strategies. Recent advances in our understanding of the mechanisms of the condition in conjunction with the development of immunomodulatory agents for managing other inflammatory diseases are helping to shape future approaches to targeted therapy. Progression will depend on collaboration and recruitment to trials. In the meantime, there is evidence to suggest that earlier diagnosis and better follow-up and management of CD may prevent the development of refractoriness.

Immunopathogenesis and therapeutic approaches in pediatric celiac disease

Celiac Disease is an autoimmune enteropathy with increasing incidence worldwide in both adults and children. It occurs as an inflammatory condition with destruction of the normal architecture of villi on consumption of gluten and related protein products found in wheat, barley and rye. However, the exact pathogenesis is not yet fully understood. A gluten-free diet remains the main modality of therapy to date. While some patients continue to have symptoms even on a gluten-free diet, adherence to this diet is also difficult, especially for the children. Hence, there is continued interest in novel methods of therapy and the current research focus is on the promising novel non-dietary modalities of treatment. Here, we critically reviewed the existing literature regarding the pathogenesis of celiac disease in children including the role of in-utero exposure leading to neonatal and infant sensitization and its application for the development of new therapeutic approaches for these patients.

A biased view toward celiac disease

Celiac disease is an autoimmune-like disorder that is triggered by dietary gluten and has a strong genetic association with the human leukocyte antigen locus, specifically, HLA-DQ2.5/DQ8. Here, Dahai-Koirala et al. apply ex vivo single-cell sequencing of TCRs from celiac disease patients, and show that biased T-cell receptor usage underpins the response to two gluten epitopes, which has implications for disease pathogenesis, diagnosis, and treatment.

Coeliac screening in a Scottish cohort of children with type 1 diabetes mellitus: is DQ typing the way forward?

BACKGROUND

Children with type 1 diabetes mellitus (T1DM) are at increased risk of coeliac disease (CD). Recent guidelines indicate coeliac screening should include HLA typing for CD predisposing (DQ2/DQ8) alleles and those negative for these alleles require no further coeliac screening.

METHODS

Children (n=176) with T1DM attending clinics across two Scottish regions were screened for HLA DQ2/DQ8 as part of routine screening. Data collected included the frequency of DQ2/DQ8 genotypes and the additional cost of HLA screening.

RESULTS

Overall, DQ2/DQ8 alleles were identified in 94% of patients. The additional cost of HLA typing was £3699.52 (£21.02 per patient). All patients with known CD (11/176) were positive for DQ2/DQ8 and all were diagnosed with CD within 5 years of T1DM diagnosis.

CONCLUSIONS

The vast majority of children with T1DM have CD-predisposing HLA genotypes limiting the number of patients that can be excluded from further screening. We conclude that HLA genotyping is not currently indicated for CD screening in this population.