The incidence of gluten-related disorders (GRDs) continues to increase and its global prevalence is estimated at approximately 5% of the population. Celiac disease (CD), dermatitis herpetiformis (DH), gluten ataxia (GA), wheat allergy (WA), and non-celiac gluten sensitivity (NCGS) are the five major GRDs that present with a wide range of clinical manifestations. The diagnosis of GRDs can be challenging because the typical and atypical clinical manifestations of the GRDs overlap. In this review, the current definitions of gluten-related disorders, focusing on their clinical features, diagnostic and therapeutic approaches are presented. We concluded that GRDs are usually diagnosed using a combination of clinical features, serological tests, and histopathological findings. Treatment usually involves dietary modification.

Wheat flour is one of the most important food ingredients containing several essential nutrients including proteins. Gluten is one of the major protein components of wheat consisted of glutenin (encoded on chromosome 1) and gliadin (encoded on chromosome 1 and 6) and there are around hundred genes encoding it in wheat. Gluten proteins have the ability of eliciting the pathogenic immune responses and hypersensitivity reactions in susceptible individuals called “gluten-related disorders (GRDs)”, which include celiac disease (CD), wheat allergy (WA), and non-celiac gluten sensitivity (NCGS). Currently removing gluten from the diet is the only effective treatment for mentioned GRDs and studies for the appropriate and alternative therapeutic approaches are ongoing. Accordingly, several genetic studies have focused on breeding wheat with low immunological properties through gene editing methods. The present review considers genetic characteristics of gluten protein components, focusing on their role in the incidence of gluten-related diseases, and genetic modifications conducted to produce wheat with less immunological properties.

Background Coronavirus disease 2019 (COVID-19) is defined as an emerging infectious disease caused by severe acute respiratory syndrome coronavirus 2 and celiac disease (CD) is one of the autoimmune multiorgan diseases, which can be accompanied by an increased risk of viral infections. CD patients, especially untreated subjects, may be at greater risk of infections such as viral illnesses. Interleukin (IL)-6, CD4, CD25, and FOXP3 are known as genes affecting immune homeostasis and relate to the inflammation state. This study aimed to compare the expression levels of aforementioned genes in peripheral blood samples of CD and severe COVID-19 patients. Methods Sixty newly diagnosed CD patients with median age (mean ± SD) of 35.40 ± 24.12 years; thirty confirmed severe COVID-19 patients with median age (mean ± SD) of 59.67 ± 17.22, and 60 healthy subjects with median age (mean ± SD) of 35.6 ± 13.02 years; were recruited from March to September 2020. Fresh whole blood samples were collected, total RNA was obtained and cDNA synthesis was carried out. RNA expression levels of IL-6, CD4, CD25, and FOXP3 genes were assessed using real-time quantitative RT-PCR according to the 2−∆∆Ct formula. Statistical analysis was performed using SPSS (V.21) and GraphPad, Prism (V.6). Results While increased expression of CD4, CD25, and FOXP3 was observed in CD patients compared to the control group (p = 0.02, p = 0.03, and p < 0.0001 respectively) and COVID-19 patients group (p < 0.0001 for all of them), their expression levels in COVID-19 patients decreased compared to controls (p < 0.0001, p = 0.01, p = 0.007, respectively). Increased IL-6 expression was observed in both groups of patients compared to controls (p < 0.0001 for both of them). Conclusions Although untreated CD patients may be at greater risk of developing into severe COVID-19 if they are infected by SARS-CoV-2 virus (due to their high expression of IL-6), increased expression of anti-inflammatory markers in these patients may be beneficial for them with the ability of reducing the severity of COVID-19 disease, which needs to be proven in future studies involving celiac patients infected with COVID-19.

CD is a systemic immune-mediated disorder caused by the dietary gluten in individuals who are genetically susceptible to the disease. In fact, CD is a T cell-mediated immune disease in which gluten-derived peptides activate the lamina propria CD4 + Teff cells, and these T-cell subsets can cause the intestinal tissue damages. Also, there are additional subsets of CD4 + T cells with suppressor functions. These subsets express the master transcription factor, FOXP3, and include Tr1 cells and CD4 + CD25 + Tregs, which are the main population involved in maintaining the peripheral tolerance, preventing the autoimmune diseases and limiting the chronic inflammatory diseases such as CD. The suppressive function of Tregs is important to maintain the immune homeostasis. This paper examined the features and the basic mechanisms used by Tregs to mediate the suppression in CD.

Gluten proteins are known as immunological triggers for inflammation resulting in mucosal lesions in patients with coeliac disease (CD). Adherence to a strict gluten-free diet (GFD) is currently known as the only effective treatment for CD. In this study, we performed a systematic review and dose-response meta-analysis on data from previous studies to investigate the association between different gluten doses administered and the risk of CD relapse. Electronic databases were systematically searched to retrieve studies that investigated the response of CD patients to different amounts of gluten intake and evaluated the clinical, serologic, and/or histologic evidence to recognize disease relapse. Study-specific relative risks (RRs) were combined using a random effects model. A total of 440 identified published papers were screened, of which 7 records were selected following full-text reviewing and eligibility assessment for dose-response meta-analysis. According to our analysis, the risk of CD relapse is estimated to be 0.2% (RR: 1.002; 95% CI: 1.001 to 1.004) following the consumption of 6 mg gluten/day, which was increased to 7% (RR: 1.07; 95% CI: 1.03 to 1.10), 50% (RR: 1.50; 95% CI: 1.23 to 1.82), 80% (RR: 1.80; 95% CI: 1.36 to 2.38), and 100% (RR: 2.00; 95% CI: 1.43 to 2.78) by the daily intake of 150, 881, 1276, and 1505 mg gluten, respectively. Although good adherence to a GFD can adequately control CD-related symptoms, disease relapse might happen even with a very low dose of gluten, and the duration of exposure to gluten is also an important matter. The current literature has substantial limitations, such as relying on the data from just a few countries that were different in terms of the amount of gluten administered, the duration of the challenge, etc. Therefore, more randomized clinical trials using a standardized gluten challenge protocol are needed to confirm the findings of the present study.