The risk for celiac disease after Covid-19 infection.

BACKGROUND: Celiac disease (CD) is an autoimmune disease leading to gastrointestinal symptoms and mineral deficiencies. The pathogenetic mechanisms, besides the clear HLA association, are elusive. Among environmental factors infections have been proposed. Covid-19 infection results in a systemic inflammatory response that often also involves the gastrointestinal tract. The aim of the present study was to investigate whether Covid-19 infection could increase the risk for CD. PATIENTS AND METHODS: All patients, both children and adults, in the county Skåne (1.4 million citizens) in southern Sweden with newly diagnosed biopsy- or serology-verified CD or a positive tissue transglutaminase antibody test (tTG-ab) during 2016-2021 were identified from registries at the Departments of Pathology and Immunology, respectively. Patients with a positive Covid-19 PCR or antigen test in 2020 and 2021 were identified from the Public Health Agency of Sweden. RESULTS: During the Covid-19 pandemic (March 2020 - December 2021), there were 201 050 cases of Covid-19 and 568 patients with biopsy- or serology-verified CD or a first-time positive tTG-ab tests, of which 35 patients had been infected with Covid-19 before CD. The incidence of verified CD and tTG-ab positivity was lower in comparison to before the pandemic (May 2018 - February 2020; 22.5 vs. 25.5 cases per 100 000 person-years, respectively, incidence rate difference (IRD) -3.0, 95% CI -5.7 - -0.3, p = 0.028). The incidence of verified CD and tTG-ab positivity in patients with and without prior Covid-19 infection was 21.1 and 22.4 cases per 100 000 person-years, respectively (IRD - 1.3, 95% CI -8.5-5.9, p = 0.75). CONCLUSIONS: Our results indicate that Covid-19 is not a risk factor for CD development. While gastrointestinal infections seem to be an important part of the CD pathogenesis, respiratory infections probably are of less relevance.

Salivary proteomic analysis in asymptomatic and symptomatic SARS-CoV-2 infection: Innate immunity, taste perception and FABP5 proteins make the difference.

BACKGROUND AND AIM: SARS-CoV-2 infection spawns from an asymptomatic condition to a fatal disease. Age, comorbidities, and several blood biomarkers are associated with infection outcome. We searched for biomarkers by untargeted and targeted proteomic analysis of saliva, a source of viral particles and host proteins. METHODS: Saliva samples from 19 asymptomatic and 16 symptomatic SARS-CoV-2 infected subjects, and 20 controls were analyzed by LC-MS/MS for untargeted peptidomic (flow through of 10 kDa filter) and proteomic (trypsin digestion of filter retained proteins) profiling. RESULTS: Peptides from 53 salivary proteins were identified. ADF was detected only in controls, while IL1RA only in infected subjects. PRPs, DSC2, FABP5, his-1, IL1RA, PRH1, STATH, SMR3B, ANXA1, MUC7, ACTN4, IGKV1-33 and TGM3 were significantly different between asymptomatic and symptomatic subjects. Retained proteins were 117, being 11 highly different between asymptomatic and symptomatic (fold change ≥2 or ≤-2). After validation by LC-MS/MS-SRM (selected reaction monitoring analysis), the most significant discriminant proteins at PCA were IL1RA, CYSTB, S100A8, S100A9, CA6, and FABP5. CONCLUSIONS: The differentially abundant proteins involved in innate immunity (S100 proteins), taste (CA6 and cystatins), and viral binding to the host (FABP5), appear to be of interest for use as potential biomarkers and drugs targets.

Features of ZED1227: The First-In-Class Tissue Transglutaminase Inhibitor Undergoing Clinical Evaluation for the Treatment of Celiac Disease.

ZED1227 is a small molecule tissue transglutaminase (TG2) inhibitor. The compound selectively binds to the active state of TG2, forming a stable covalent bond with the cysteine in its catalytic center. The molecule was designed for the treatment of celiac disease. Celiac disease is an autoimmune-mediated chronic inflammatory condition of the small intestine affecting about 1-2% of people in Caucasian populations. The autoimmune disease is triggered by dietary gluten. Consumption of staple foods containing wheat, barley, or rye leads to destruction of the small intestinal mucosa in genetically susceptible individuals, and this is accompanied by the generation of characteristic TG2 autoantibodies. TG2 plays a causative role in the pathogenesis of celiac disease. Upon activation by Ca2+, it catalyzes the deamidation of gliadin peptides as well as the crosslinking of gliadin peptides to TG2 itself. These modified biological structures trigger breaking of oral tolerance to gluten, self-tolerance to TG2, and the activation of cytotoxic immune cells in the gut mucosa. Recently, in an exploratory proof-of-concept study, ZED1227 administration clinically validated TG2 as a "druggable" target in celiac disease. Here, we describe the specific features and profiling data of the drug candidate ZED1227. Further, we give an outlook on TG2 inhibition as a therapeutic approach in indications beyond celiac disease.

Evidence supporting safe diagnosis of coeliac disease in children with antitissue transglutaminase titre ≥5 times upper limit of normal.

OBJECTIVE: European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) guidelines on coeliac disease (CD) recommend that children who have IgA-based antitissue transglutaminase (TGA-IgA) titre ≥10× upper limit of normal (ULN) and positive antiendomysial antibody, can be reliably diagnosed with CD via the no-biopsy pathway. The aim of this study was to examine the relationship between TGA-IgA ≥5×ULN and histologically confirmed diagnosis of CD. METHODS: Data including TGA-IgA levels at upper gastrointestinal endoscopy and histological findings from children diagnosed with CD following endoscopy from 2006 to 2021 were analysed. CD was confirmed by Marsh-Oberhuber histological grading 2 to 3 c. Statistical analysis was performed using χ² analysis (p<0.05= significant). RESULTS: 722 of 758 children had histological confirmation of CD. 457 children had TGA-IgA ≥5×ULN and 455 (99.5%) of these had histological confirmation for CD; the two that did not had eventual diagnosis of CD based on clinicopathological features. 114 of 457 had between TGA-IgA ≥5×ULN and <10×ULN, all had confirmed CD. The likelihood of a positive biopsy with TGA-IgA ≥5×ULN (455/457) compared with TGA-IgA <5×ULN (267/301) has strong statistical significance (p<0.00001). The optimal TGA-IgA cut-off from receiver operating characteristic curve analysis was determined to be below 5×ULN for the two assays used. CONCLUSION: 99.5% of children with TGA-IgA ≥5×ULN had histological confirmation of CD, suggesting that CD diagnosis can be made securely in children with TGA-IgA ≥5×ULN. If other studies confirm this finding, there is a case to be made to modify the ESPGHAN guidelines to a lower threshold of TGA-IgA for serological diagnosis of CD.

Saliva changes in composition associated to COVID-19: a preliminary study.

The coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV 2), is usually associated with a wide variety of clinical presentations from asymptomatic to severe cases. The use of saliva as a diagnostic and monitoring fluid has gained importance since it can be used to investigate the immune response and to direct quantification of antibodies against COVID-19. Additionally, the use of proteomics in saliva has allowed to increase  our understanding of the underlying pathophysiology of diseases, bringing new perspectives on diagnostics, monitoring, and treatment. In this work, we compared the salivary proteome of 10 patients with COVID-19, (five patients with mild and five patients with severe COVID-19) and ten control healthy patients. Through the application of proteomics, we have identified 30 proteins whose abundance levels differed between the COVID-19 groups and the control group. Two of these proteins (TGM3 and carbonic anhydrase-CA6) were validated by the measurement of gGT and TEA respectively, in 98 additional saliva samples separated into two groups: (1) COVID-19 group, integrated by 66 patients who tested positive for COVID-19 (2) control group, composed of 32 healthy individuals who did not show any sign of disease for at least four weeks and were negative for COVID-19 in RT-PCR. In the proteomic study there were observed upregulations in CAZA1, ACTN4, and ANXA4, which are proteins related to the protective response against the virus disturbance, and the upregulation of TGM3, that is correlated to the oxidative damage in pulmonary tissue. We also showed the downregulation in cystatins and CA6 that can be involved in the sensory response to stimulus and possibly related to the presence of anosmia and dysgeusia during the COVID-19. Additionally, the presence of FGB in patients with severe COVID-19 but not in mild COVID-19 patients could indicate a higher viral aggregation and activation in these cases. In conclusion, the salivary proteome in patients with COVID-19 showed changes in proteins related to the protective response to viral infection, and the altered sensory taste perception that occur during the disease. Moreover, gGT and TEA could be potential biomarkers of respiratory complications that can occurs during COVID 19 although further larger studies should be made to corroborate this.

Determination of Urinary Gluten Immunogenic Peptides to Assess Adherence to the Gluten-Free Diet: A Randomized, Double-Blind, Controlled Study.

INTRODUCTION: The adherence to a gluten-free diet (GFD) is a trending topic in the management of celiac disease. The aim of our study was to evaluate the diagnostic performance of urinary gluten immunogenic peptides (GIP) determination to detect gluten contamination of the GFD. METHODS: In study A, 25 healthy adults on a standard GFD performed 6 gluten challenges (0, 10, 50, 100, 500, and 1,000 mg) with quantification of urinary GIP before (T0) and during the following 24 hours. In study B, 12 participants on a gluten contamination elimination diet underwent urinary GIP determination at T0 and after challenge with 5 or 10 mg gluten. Urine GIP concentration was determined by an immunochromatographic assay. RESULTS: In study A, 51 of 150 baseline urine samples were GIP+ on GFD and 7 of 17 were GIP+ after the zero-gluten challenge, whereas only 55 of 81 were GIP+ after the 10-1,000 mg gluten challenges. There was no significant change in the 24-hour urinary GIP when increasing gluten from 10 to 1,000 mg. In study B, 24 of 24 baseline urine samples were GIP-, whereas 8 of 24 were GIP+ after 5 or 10 mg of gluten. DISCUSSION: Traces of gluten in the standard GFD may cause positivity of urinary GIP determination, whereas a false negativity is common after a gluten intake of 10-1,000 mg. Owing to the impossibility of standardizing the test in normal conditions, it seems unlikely that urinary GIP determination may represent a reliable tool to assess the compliance to the GFD of patients with celiac disease or other gluten-related disorders.

Unique autoantibody prevalence in long-term recovered SARS-CoV-2-infected individuals.

The variability in resolution of SARS-CoV-2-infections between individuals neither is comprehended, nor are the long-term immunological consequences. To assess the long-term impact of a SARS-CoV-2-infection on the immune system, we conducted a prospective study of 80 acute and former SARS-CoV-2 infected individuals and 39 unexposed donors to evaluate autoantibody responses and immune composition. Autoantibody levels against cyclic citrullinated peptide (CCP), a specific predictor for rheumatoid arthritis (RA), were significantly (p = 0.035) elevated in convalescents only, whereas both acute COVID-19 patients and long-term convalescents showed critically increased levels of anti-tissue transglutaminase (TG), a specific predictor of celiac disease (CD) (p = 0.002). Both, anti-CCP and anti-TG antibody levels were still detectable after 4-8 months post infection. Anti-TG antibodies occurred predominantly in aged patients in a context of a post-SARS-CoV-2-specific immune composition (R2 = 0.31; p = 0.044). This study shows that increased anti-CCP and anti-TG autoantibody levels can remain long-term after recovering even from mildly experienced COVID-19. The inter-relationship of the lung as viral entry side and RA- and CD-associated autoimmunity indicates that a SARS-CoV-2-infection could be a relevant environmental factor in their pathogenesis.

Transglutaminase 2 Regulates Innate Immunity by Modulating the STING/TBK1/IRF3 Axis.

We have recently shown that type 2 transglutaminase (TG2) plays a key role in the host's inflammatory response during bacterial infections. In this study, we investigated whether the enzyme is involved in the regulation of the STING pathway, which is the main signaling activated in the presence of both self- and pathogen DNA in the cytoplasm, leading to type I IFN (IFN I) production. In this study, we demonstrated that TG2 negatively regulates STING signaling by impairing IRF3 phosphorylation in bone marrow-derived macrophages, isolated from wild-type and TG2 knockout mice. In the absence of TG2, we found an increase in the IFN-ß production and in the downstream JAK/STAT pathway activation. Interestingly, proteomic analysis revealed that TG2 interacts with TBK1, affecting its interactome composition. Indeed, TG2 ablation facilitates the TBK1-IRF3 interaction, thus indicating that the enzyme plays a negative regulatory effect on IRF3 recruitment in the STING/TBK1 complex. In keeping with these findings, we observed an increase in the IFNß production in bronchoalveolar lavage fluids from COVID-19-positive dead patients paralleled by a dramatic decrease of the TG2 expression in the lung pneumocytes. Taken together, these results suggest that TG2 plays a negative regulation on the IFN-ß production associated with the innate immunity response to the cytosolic presence of both self- and pathogen DNA.

ESPGHAN 'biopsy-sparing' guidelines for celiac disease in children with low antitransglutaminase during COVID-19.

OBJECTIVES: Recent guidelines for celiac disease have allowed a biopsy-free approach in endomysial antibodies (EMAs) positive children with high antitransglutaminase (TGA-IgA) titer [>10 time upper limit of normal (ULN)]. Esophagogastroduodenoscopy is still necessary for diagnosis in children with lower title. Because elective pediatric endoscopy has been substantially shouted down during coronavirus disease (COVID-19) pandemic, many children remained undiagnosed - and therefore untreated - for a long time. We aimed to analyze the feasibility and accuracy of a biopsy-free approach in suspected celiac disease children with TGA-IgA values <10 ULN to facilitate the diagnostic process by avoiding endoscopy. METHODS: In this study cohort, we retrospectively analyzed all biopsy-confirmed diagnosis of celiac disease in our center (between 2014 and 2019). The positive predictive value (PPV) of TGA-IgA titers between 5 and 10 ULN and positive EMA in diagnosing celiac disease were determined. Mucosal atrophy and resolution of symptoms after gluten-free diet (GFD) were considered to confirm initial diagnosis. RESULTS: Of 430 celiac disease patients (F: 274; mean age 7.54 years) diagnosed by endoscopy, 84 (F: 46; mean age 8 years) with TGA-IgA between 5 and 10 ULN and positive EMA were identified. The PPV of TGA-IgA between 5 and 10 ULN and positive EMA was 0.93 (95% confidence interval 0.90-0.96). All these children had a symptom resolution and antibodies normalization after GFD. CONCLUSION: During the COVID-19 outbreak, a temporarily reduction of the TGA-IgA threshold for biopsy-sparing approach seems feasible in EMA positive children with TGA-IgA between 5 and 10 ULN.