Validation of a novel single-drop rapid human leukocyte antigen-DQ2/-DQ8 typing method to identify subjects susceptible to celiac disease

Sieving out non-celiac gluten sensitivity amongst patients with irritable bowel syndrome

OBJECTIVES

It is challenging to make diagnosis of non-celiac gluten sensitivity/non-celiac wheat sensitivity (NCGS/NCWS) in clinical practice, since there is no biomarker and diagnosis is based on response to gluten-free-diet (GFD). We used anti-gliadin antibody (AGA) for screening patients with IBS for gluten-sensitivity.

METHODS

492 Adult-patients with IBS underwent screening for celiac disease and gluten-sensitivity using IgA anti-tissue transglutaminase antibody and IgA-AGA and IgG-AGA, respectively. Patients with positive AGA (IgA and/or IgG) were invited to follow GFD, those willing were put on GFD for 6-weeks. Responsive patients were given gluten re-challenge. Diagnosis of NCGS was confirmed if they had recurrence of symptoms.

RESULTS

Of 492 patients with IBS, AGA was positive in 61(12.4 %), hence suspected to have gluten-sensitivity. Of 31 who agreed to participate and followed GFD for 6-weeks, 17 (54.8 %) had complete (>30 % improvement) and 10(32.2 %) had partial (>20 % improvement) response. All 17 complete-responders were given gluten re-challenge for 6-weeks, symptoms recurred in all and hence were confirmed to have NCGS/NCWS. Significant decrease in AGA levels occurred almost in all GFD-responders.

CONCLUSIONS

12.4 % IBS patients have biological evidence of gluten/wheat-sensitivity. Almost 87 % patients with IBS having AGA responded to GFD. The value of AGA may further be explored as a biomarker for screening for the presence of NCGS, before recommending this test for the clinical practice.

Tailoring crops with superior product quality through genome editing: an update

In this review, using genome editing, the quality trait alterations in important crops have been discussed, along with the challenges encountered to maintain the crop products' quality. The delivery of economic produce with superior quality is as important as high yield since it dictates consumer's acceptance and end use. Improving product quality of various agricultural and horticultural crops is one of the important targets of plant breeders across the globe. Significant achievements have been made in various crops using conventional plant breeding approaches, albeit, at a slower rate. To keep pace with ever-changing consumer tastes and preferences and industry demands, such efforts must be supplemented with biotechnological tools. Fortunately, many of the quality attributes are resultant of well-understood biochemical pathways with characterized genes encoding enzymes at each step. Targeted mutagenesis and transgene transfer have been instrumental in bringing out desired qualitative changes in crops but have suffered from various pitfalls. Genome editing, a technique for methodical and site-specific modification of genes, has revolutionized trait manipulation. With the evolution of versatile and cost effective CRISPR/Cas9 system, genome editing has gained significant traction and is being applied in several crops. The availability of whole genome sequences with the advent of next generation sequencing (NGS) technologies further enhanced the precision of these techniques. CRISPR/Cas9 system has also been utilized for desirable modifications in quality attributes of various crops such as rice, wheat, maize, barley, potato, tomato, etc. The present review summarizes salient findings and achievements of application of genome editing for improving product quality in various crops coupled with pointers for future research endeavors.

Meta-Analysis and Systematic Review of HLA DQ2/DQ8 in Adults with Celiac Disease

Although people with human leukocyte antigens (HLA) DQ2 and/or DQ8 are more likely to develop celiac disease (CD), the condition cannot be fully explained by this genetic predisposition alone. Multiple, as yet unidentified, factors contribute to the genesis of CD, including genetics, the environment, and the immune system. In order to provide insight into a prospective possibility and an expanded screening technique, we aim to undertake a comprehensive and meta-analytical study of the assessment and distribution of HLA class II (HLA-DQ2/DQ8) in adult CD patients. A systematic review was conducted using an electronic search of databases (PubMed, Google Scholar, Embase, and Direct Science) from January 2004 to February 2022. DQ2/DQ2 homozygotes have the highest risk of developing CD. DQ2/DQ8 typing is an effective test to exclude CD from the differential diagnosis of a patient with CD symptoms. Although other non-HLA genes have been associated with CD, they are rarely considered at diagnosis because they account for only a small proportion of the heritability of CD. This finding, together with the information gathered previously, may be useful in considering widely available and economically feasible screening options for celiac disease in young people.

Distribution of celiac disease predisposing genes HLA-DQ2 and HLA-DQ8 in the native population of southern India

BACKGROUND

Celiac disease (CD) is an intestinal inflammatory condition caused by the ingestion of gluten peptides in wheat and related grains in individuals carrying HLA-DQ2 and/or HLA-DQ8 genes. In comparison to HLA-DQ8, a higher HLA-DQ2 prevalence is reported in European population where wheat has been the staple food for thousands of years. In non-European population, this pattern of HLA-DQ CD-predisposing gene distribution has not always been found. The aim of this study was to evaluate the HLA-DQ2 and HLA-DQ8 distribution in the native low-gluten consuming southern Indian population.

METHODS

Overall, 211 dried blood spots (DBS) were collected from native southern Indian individuals. HLA-DQ characterization and the determination of homozygous/heterozygous status were performed using commercially available HLA-DQ typing kits.

RESULTS

Of 211 collected DBS, 88 (42%, 95% CI: 36-48) were positive for HLA-DQ2 and/or HLA-DQ8 heterodimers. Overall, 40 (19%, 95% CI: 14-24) samples typed positive for HLA-DQ2 and 48 (23%, 95% CI: 18-28) typed positive for HLA-DQ8 genotypes. Of 40 HLA-DQ2-positive individuals, only one subject tested homozygous for the DQB1*02 allele.

CONCLUSIONS

In the southern Indian native general population, the prevalence of HLA-DQ8 is higher in comparison to HLA-DQ2 prevalence. This finding could be related to the delayed introduction of wheat in the diet of the southern Indian population.

Wheat Breeding, Fertilizers, and Pesticides: Do They Contribute to the Increasing Immunogenic Properties of Modern Wheat?

Celiac disease (CD) is a small intestinal inflammatory condition where consumption of gluten induces a T-cell mediated immune response that damages the intestinal mucosa in susceptible individuals. CD affects at least 1% of the world’s population. The increasing prevalence of CD has been reported over the last few decades. However, the reason for this increase is not known so far. Certain factors such as increase in awareness and the development of advanced and highly sensitive diagnostic screening markers are considered significant factors for this increase. Wheat breeding strategies, fertilizers, and pesticides, particularly herbicides, are also thought to have a role in the increasing prevalence. However, less is known about this issue. In this review, we investigated the role of these agronomic practices in depth. Our literature-based results showed that wheat breeding, use of nitrogen-based fertilizers, and herbicides cannot be solely responsible for the increase in celiac prevalence. However, applying nitrogen fertilizers is associated with an increase in gluten in wheat, which increases the risk of developing celiac-specific symptoms in gluten-sensitive individuals. Additionally, clustered regularly interspaced short palindromic repeats (CRISPR) techniques can edit multiple gliadin genes, resulting in a low-immunogenic wheat variety that is safe for such individuals.

Human Leukocyte Antigen DQ (HLA-DQ) genotypes and haplotypes and their association with phenotype in patients with celiac disease in India

Background and Aim

Human Leukocyte Antigen DQ (HLA‐DQ) genotypes play a permissive role in the genesis of celiac disease (CeD). In this case–control study, we used next‐generation sequencing to determine HLA‐DQA1 and ~DQB1 genotypes and haplotypes associated with CeD in Indian patients.

Methods

HLA‐DQA1 and ~DQB1 loci were amplified, using long‐range polymerase chain reaction (PCR), from DNA of 259 patients with symptomatic CeD (160 typical and 99 atypical), 45 asymptomatic CeD, 96 potential CeD, and 300 healthy adults. Amplicons were fragmented and sequenced on the Illumina platform, and alleles and haplotypes were assigned by matching against the HLA‐international ImMunoGeneTics (IMGT) database.

Results

HLA‐DQA1*05:01 (odds ratio [OR] 8.39, 95% confidence interval [CI] 5.64–12.47) and HLA‐DQB1*02:01 (OR 8.59, 95% CI 5.75–12.83) were the genotypes that showed a risk association with symptomatic CeD. Among the haplotypes, HLA‐DQA1*05:01 ~ HLA‐DQB1*02:01 (OR 8.56, 95% CI 5.67–13.19) showed a strong risk association with symptomatic CeD. When comparing symptomatic CeD with subclinical forms (asymptomatic and potential) CeD, HLA‐DQA1*05:01 ~ HLA‐DQB1*02:01 (OR 2.34, 95% CI 1.61–3.43) was significantly associated with risk of symptomatic disease. The strength of association between the HLA‐DQA1*05:01 ~ HLA‐DQB1*02:01 haplotype and the CeD phenotype showed a gradient in the order typical > atypical > asymptomatic > potential CeD. Genotypes consistent with expression of HLA DQ2 and/or 8 were noted in 128 (80%) typical, 73 atypical (74%), 27 (60%) asymptomatic, and 52 (54%) potential CeD participants.

Conclusion

HLA‐DQA1*05:01 ~ HLA‐DQB1*02:01 (haplotype DQ2.5) showed a very strong risk association with symptomatic CeD in Indian patients. The strength of association showed a gradient of increase from potential to typical CeD, coinciding with a phenotypic change in the celiac iceberg.

Current Status and Perspectives on the Application of CRISPR/Cas9 Gene-Editing System to Develop a Low-Gluten, Non-Transgenic Wheat Variety

Wheat gluten contains epitopes that trigger celiac disease (CD). A life-long strict gluten-free diet is the only treatment accepted for CD. However, very low-gluten wheat may provide an alternative treatment to CD. Conventional plant breeding methods have not been sufficient to produce celiac-safe wheat. RNA interference technology, to some extent, has succeeded in the development of safer wheat varieties. However, these varieties have multiple challenges in terms of their implementation. Clustered Regularly Interspaced Short Palindromic Repeats-associated nuclease 9 (CRISPR/Cas9) is a versatile gene-editing tool that has the ability to edit immunogenic gluten genes. So far, only a few studies have applied CRISPR/Cas9 to modify the wheat genome. In this article, we reviewed the published literature that applied CRISPR/Cas9 in wheat genome editing to investigate the current status of the CRISPR/Cas9 system to produce a low-immunogenic wheat variety. We found that in recent years, the CRISPR/Cas9 system has been continuously improved to edit the complex hexaploid wheat genome. Although some reduced immunogenic wheat varieties have been reported, CRISPR/Cas9 has still not been fully explored in terms of editing the wheat genome. We conclude that further studies are required to apply the CRISPR/Cas9 gene-editing system efficiently for the development of a celiac-safe wheat variety and to establish it as a "tool to celiac safe wheat".

X6: A Novel Antibody for Potential Use in Gluten Quantification

Gliadin is a fraction of gluten, known to trigger celiac disease in susceptible people. To date, the life-long gluten-free diet is used for the prevention of this disease. Hence, methods for gluten control in foods are of significant importance. Being one of the most-used methods used for this purpose, ELISA should use high-affinity antibodies to gliadin peptides involved into celiac process. This study investigates the characteristics of a novel anti-gliadin antibody X6. We found the QXQPFPXP site to be a recognized epitope that provides specific binding of the antibody to cereal prolamins involved in celiac disease manifestation. A specificity study using immunoblotting shows the recognition of wheat, barley and rye proteins-as well as α-gliadin homologs from non-edible cereals (Dasypyrum villosum). Reactivity to avenin was less pronounced, as this protein does not contain the PFP motif most critical for antibody recognition. The proteins of Zea mays and Setaria italica were not recognized by X6. X6-based ELISA highly correlated with R5 and G12, which are Codex Alimentarius standards in the quantitative assessment of gluten content (Pearson's R = 0.86 and 0.87, respectively). Qualitative assessment revealed no significant differences between R5 and G12 and X6.

Carrier frequency of HLA-DQB1*02 allele in patients affected with celiac disease: A systematic review assessing the potential rationale of a targeted allelic genotyping as a first-line screening

BACKGROUND

Celiac Disease (CD) is an immune-mediated disorder, in which the HLA immunogenetic background (DQ2 and DQ8 heterodimers) and environmental trigger (gluten) are well established. Indeed, both factors are necessary – but not sufficient – to develop CD. However, it is very likely that CD is underdiagnosed in both developing and developed countries, due to several aspects, including the fact that a lot of patients present mild and/or atypical symptoms, without the presence of any recognized risk factors. Therefore, the possibility and feasibility of widened screening strategies to identify CD patients are debated.

AIM

To provide further evidence of the main epidemiological importance of HLA-DQB1*02 allele in the population of CD patients.

METHODS

We performed a systematic search in PubMed, EMBASE, Cochrane, Web of Science and Scopus databases, in order to produce a systematic review assessing the carrier frequency of HLA-DQB1*02 allele in the celiac population. Following the PRISMA guidelines, we retrieved all the original articles describing CD patients’ HLA-DQB1 genotype in such a way that could allow to assess the HLA-DQB1*02 carrier frequency among CD patients, along with the evidence of the appropriate diagnostic work-up to achieve a correct and final diagnosis of CD.

RESULTS

The final output of this systematic search in the medical literature consisted of 38 studies providing the appropriate HLA-DQB1 genotype information of the respective CD population. According to this systematic review, including a pool of 4945 HLA-DQ genotyped CD patients, the HLA-DQB1*02 carrier frequency was 94.94%, meaning that only 5.06% of CD patients were completely lacking this allelic variant. Interestingly, if we consider only the studies whereby the prevalence of CD patients affected with type 1 diabetes mellitus was supposed or clearly established to be very low, the frequency of non-HLA-DQB1*02 carriers among CD patients dropped to 3.65%.

CONCLUSION

Such a high carrier frequency of the HLA-DQB1*02 allelic variant (which is > 95%-96% in CD patients without risk factors, like type 1 diabetes mellitus comorbidity) might be exploited to consider a cost-effective and widened screening approach. If a sustainable strategy could be implemented through a low-cost targeted genetic test to detect the individual presence of HLA-DQB1*02 allele, an appropriate algorithm for serological screening in individuals resulting to be genetically predisposed to CD, might be considered.

Increased Prevalence of Celiac Disease in School-age Children in Italy

BACKGROUND & AIMS

Celiac disease is one of the most common diseases worldwide, with an apparent trend of increasing prevalence. We investigated the prevalence of celiac disease in children in Italy in 2015-2016 and compared that with data from 25 years ago.

METHODS

We screened 4570 children (5-11 years old, 80.1% of the eligible population) from metropolitan areas of Ancona and Verona for HLA genes associated with increased risk of celiac disease, and for total serum levels of IgA and IgA class anti-tissue transglutaminase in HLA positives. Diagnoses of celiac disease were confirmed by detection of anti-endomysial antibody and analysis of intestinal biopsies. The prevalence of celiac autoimmunity and celiac disease were calculated and compared with values from the same geographical area during the years 1993-1995, after adjustment for the different diagnostic algorithm.

RESULTS

We identified 1960 children with celiac disease-associated haplotypes (43% of children screened; 95% CI, 40.8%-45.2%). The prevalence of celiac disease autoimmunity in the HLA-positive subjects was 96/1706 (5.62%; 95% CI, 4.53%-6.71%) and 54 of these children satisfied the diagnostic criteria for celiac disease. In the eligible population there were other 23 known cases of celiac disease. The overall estimated prevalence of celiac disease was 1.58% (95% CI, 1.26%-1.90%); this value is significantly higher than the 1993-1995 adjusted prevalence (0.88%; 95% CI, 0.74%-1.02%).

CONCLUSIONS

We found the prevalence of celiac disease in children in Italy to be greater than 1.5%; this value has increased significantly over the past 25 years. Studies are needed to determine the causes of this large increase.

HLA-DQB1*02 allele in children with celiac disease: Potential usefulness for screening strategies

Through a retrospective analysis of a real-life cohort of children with celiac disease (CD), who underwent HLA-DQ genotyping, we supported our previous findings indicating the presence of HLA-DQB1*02 allele in at least 90%-95% of pediatric patients. In the present study, reporting the HLA-DQ analysis from 184 children (age range: 1-16 years) diagnosed with CD in a single centre, we found that 97.29% of all these CD children (n = 179 out of 184 genotyped patients) resulted to be carriers of at least one copy of HLA-DQB1*02 allele. If a widened screening for CD should result to be appropriate in the pediatric population after further clinical research, this observation might be potentially exploited to consider a two-step screening strategy, starting with the HLA-DQB1*02 targeted analysis followed by the specific serology for CD in these predisposed patients only. However, additional and larger studies are needed to support our findings.

Relevance of HLA-DQB1*02 Allele in the Genetic Predisposition of Children with Celiac Disease: Additional Cues from a Meta-Analysis. ACTA ACUST UNITED AC. 2019;55: pii E190. [PMID: 31121940 PMCID: PMC6571594 DOI: 10.3390/medicina55050190]

Background and Objectives: Celiac disease (CD) is a multifactorial immune-mediated disorder, triggered by the ingestion of gluten in genetically-predisposed subjects carrying MHC-DQ2 and -DQ8 heterodimers, which are encoded by four HLA-DQ allelic variants, overall. This meta-analysis aims at providing further epidemiological support to the predominant relevance of one specific allele, namely HLA-DQB1*02, in the predisposition and genetic risk of CD. Materials and Methods: We performed a search of MEDLINE/PubMed, Embase, Web of Science, and Scopus, retrieving all publications (case-control study, cross-sectional, and retrospective cohort study) on the association between HLA class II polymorphisms and first-degree relatives (FDRs) of children with CD. After a critical reading of the articles, two investigators independently performed data extraction according to the following inclusion criteria: HLA class II genes, any DQ and DR molecules, and CD diagnosed following the current clinical guidelines. A third participant was consulted for discussion to reach an agreement concerning discrepancies. Results: Our search strategy selected 14 studies as being eligible for inclusion, and those were submitted for data extraction and analysis. These studies were published between 1999 and 2016 and, collectively, enrolled 3063 FDRs. Positive and negative likelihood ratios (LR+ and LR-, respectively) for CD diagnosis, according to the presence of the HLA-DQ genotype coding a complete MHC-DQ2 and/or MHC-DQ8 molecules, were 1.449 (CI 1.279-1.642) and 0.187 (CI 0.096-0.362), respectively. If only the isolated presence of HLA-DQB1*02 allele is considered, the pooled estimation of LR+ was 1.659 (CI 1.302-2.155) and, importantly, the LR- still showed a very good discriminatory power of 0.195 (CI 0.068-0.558). Conclusions: Through our differential meta-analysis, comparing the presence of the genotype coding the full MHC-DQ2 and/or DQ8 molecules with the isolated presence of HLA-DQB1*02 allelic variant, we found that the LR- of the latter analysis maintained the same value. This observation, along with previous evidences, might be useful to consider potential cost-effective widened screening strategies for CD in children.