Specific IgE for wheat in tear fluid of patients with allergic conjunctivitis

What's the situation with ocular inflammation? A cross-seasonal investigation of proteomic changes in ocular allergy sufferers' tears in Victoria, Australia

Background

Ocular allergy (OA) is a localized subset of allergy characterized by ocular surface itchiness, redness and inflammation. Inflammation and eye-rubbing, due to allergy-associated itch, are common in OA sufferers and may trigger changes to the ocular surface biochemistry. The primary aim of this study is to assess the differences in the human tear proteome between OA sufferers and Healthy Controls (HCs) across peak allergy season and off-peak season in Victoria, Australia.

Methods

19 participants (14 OA sufferers, 5 HCs) aged 18-45 were recruited for this study. Participants were grouped based on allergy symptom assessment questionnaire scoring. Proteins were extracted from human tear samples and were run on an Orbitrap Mass Spectrometer. Peaks were matched to a DIA library. Data was analyzed using the software MaxQuant, Perseus and IBM SPSS.

Results

1267 proteins were identified in tear samples of OA sufferers and HCs. 23 proteins were differentially expressed between peak allergy season OA suffers vs HCs, and 21 were differentially expressed in off-peak season. Decreased proteins in OA sufferers related to cell structure regulation, inflammatory regulation and antimicrobial regulation. In both seasons, OA sufferers were shown to have increased expression of proteins relating to inflammation, immune responses and cellular development.

Conclusion

Tear protein identification showed dysregulation of proteins involved in inflammation, immunity and cellular structures. Proteins relating to cellular structure may suggest a possible link between OA-associated itch and the subsequent ocular surface damage via eye-rubbing, while inflammatory and immune protein changes highlight potential diagnostic and therapeutic biomarkers of OA.

Allergen-specific IgE in the tear fluid of Chinese patients with common allergic conjunctivitis in autumn and winter

PURPOSE

In this study, we determined the positive rates of allergen-specific immunoglobulin E (IgE) in the tear fluid of Chinese patients with common allergic conjunctivitis (AC) in autumn and winter, compared systemic and ocular allergen tests, and explored the correlation between the numbers and categories of allergens and clinical AC features.

METHODS

This cross-sectional study recruited 44 patients with AC (86 eyes). Specific IgEs for allergens common in China (house dust mite, cat/dog dander, mugwort/ragweed pollen, cottonwood/willow/elm pollen, milk, egg whites, soybeans) were measured in collected tears using kits for allergen-specific IgE antibodies. AC signs and symptoms were graded according to severity.

RESULTS

Specific IgE in tears was positive in 87.2% of eyes. House dust mite was the most common allergen (86.0%), followed by cat (24.4%) and dog (7.0%) dander; tree and grass pollen accounted for only 4.7% and 2.3%, respectively. Food allergens were not detected. The positive rates of the systemic allergen tests were lower than in tear fluid tests in both eyes, especially for house dust mites (P = 0.000). In patients with more allergens, itching was more severe (P = 0.035), while conjunctival hyperemia was milder (P = 0.002).

CONCLUSION

In autumn and winter, the most common AC allergen in Chinese patients was house dust mites. Compared with systemic allergen tests, measuring specific IgE in tears may be a non-invasive method to diagnose and evaluate AC severity, which may be more suitable to reflect the local conditions of ocular surface inflammation due to its high positive rate and convenience.

IgE Mediated Wheat Allergy Associated with Resistant and Severe Forms of Allergic Conjunctivitis

Objective:

This study aimed to determine the prevalence and criteria of wheat allergy (WA) among patients with resistant allergic conjunctivitis (AC).

Methods:

A prospective comparative study was conducted on 100 patients with resistant AC. Skin prick-tests (SPTs), total and sIgE against a panel of inhalant and food allergens were performed in all patients’ sera. They were divided into 2 groups according to skin prick test (SPT) and specific IgE (sIgE) level, namely the wheat sensitive group (WSG) and wheat tolerant group (WTG). Total ocular symptom scores (TOSS) and 4-point sign scales were correlated for both groups.

Results:

Ten patients out of 100 with IgE-mediated resistant AC were wheat sensitive, and the other 90 were wheat tolerant patients. WSG included patients of significantly younger age. Positive family history of atopy was proven in 100% of WSG vs. 67% of WTG. A significantly higher frequency of multiorgan allergy was detected in 100% of WSG vs. 20% in WTG (P = 0.0001). Thirty (30%) of WSG had associated allergic rhinitis (AR) and bronchial asthma (BA). Another 30% had an associated AR only, 10% had an associated BA only, and another 20% had an associated skin allergy. TOSS, 4- point sign scale, and total IgE level were significantly higher in WSG.

Conclusion:

This study provides novel evidence that wheat allergy is responsible for some severe forms of AC.

A Mouse-Based Method to Monitor Wheat Allergens in Novel Wheat Lines and Varieties Created by Crossbreeding: Proof-of-Concept Using Durum and A. tauschii Wheats

Wheat allergies are potentially life-threatening because of the high risk of anaphylaxis. Wheats belong to four genotypes represented in thousands of lines and varieties. Monitoring changes to wheat allergens is critical to prevent inadvertent ntroduction of hyper-allergenic varieties via breeding. However, validated methods for this purpose are unavailable at present. As a proof-of-concept study, we tested the hypothesis that salt-soluble wheat allergens in our mouse model will be identical to those reported for humans. Groups of Balb/cJ mice were rendered allergic to durum wheat salt-soluble protein extract (SSPE). Using blood from allergic mice, a mini hyper-IgE plasma bank was created and used in optimizing an IgE Western blotting (IEWB) to identify IgE binding allergens. The LC-MS/MS was used to sequence the allergenic bands. An ancient Aegilops tauschii wheat was grown in our greenhouse and extracted SSPE. Using the optimized IEWB method followed by sequencing, the cross-reacting allergens in A. tauschii wheat were identified. Database analysis showed all but 2 of the durum wheat allergens and all A. tauschii wheat allergens identified in this model had been reported as human allergens. Thus, this model may be used to identify and monitor potential changes to salt-soluble wheat allergens caused by breeding.

A Review of Emerging Tear Proteomics Research on the Ocular Surface in Ocular Allergy

Ocular allergy is an immunoglobulin E-mediated Type I hypersensitivity reaction localised to the ocular surface and surrounding tissues. Primary signs and symptoms of ocular allergy include itching, redness, irritation and inflammation. Eye-rubbing caused by itching has been shown to alter ocular surface protein concentrations in conditions linked to ocular allergy such as keratoconus. In keratoconus, the cornea begins to thin and sag over time, leading to progressive vision loss and blindness in severe conditions. Due to the high incidence of ocular allergy sufferers rubbing their eyes in response to symptoms of itching, the protein landscape of the ocular surface may be significantly altered. Differential protein expression caused by long-term inflammation and eye-rubbing may lead to subsequent changes in ocular surface structure and function over time. This review aims to summarise and explore the findings of current ocular allergy proteome research conducted using techniques such as gel electrophoresis, mass spectrometry and lab-on-a-chip proteomics. Proteins of interest for this review include differentially expressed immunoglobulins, mucins, functional proteins, enzymes and proteins with previously uncharacterised roles in ocular allergy. Additionally, potential applications of this research are addressed in terms of diagnostics, drug development and future research prospects.

Relationship among total tear IgE, specific serum IgE, and total serum IgE levels in patients with pollen-induced allergic conjunctivitis

Background

Recently, the number of patients with pollinosis, particularly Japanese cedar pollinosis, has markedly increased. We previously reported about local allergic conjunctivitis, which is a phenotype of allergic conjunctivitis (AC). AC cases are often sensitized by various antigens. This study aimed to investigate the relationship among total tear IgE (t-tIgE), specific serum IgE (s-sIgE), and total serum IgE (t-sIgE) levels in patients with pollen-induced AC.

Methods

In 2019, 1372 patients were clinically diagnosed with AC at the Yamana Eye Clinic using t-tIgE, t-sIgE, and s-sIgE tests against 39 allergens. Among the pollen-induced AC patients who underwent allergen testing, 99 tested positives for s-sIgE against pollen. The subjects comprised 33 (33.3%) male and 66 (66.7%) female individuals aged 9–86 years.

Results

The t-tIgE test was positive in 68 (68.7%) patients and negative in 31 (31.3%) patients. In the t-sIgE test, 45 (45.5%) patients had t-sIgE levels above the reference value of 170 IU/mL. The higher the total score of the positive class value of each pollen-specific IgE (pollen-sIgE) antibody, the higher the positive rate of t-tIgE (p < 0.001). Of 32 patients in whom food-specific IgE (food-sIgE) was detected, 81.3% of the pollen-sIgE-positive and food-sIgE-positive cases were also positive for t-sIgE and t-tIgE. However, significant difference was not found between the total score of food-sIgE of the t-tIgE positive group and negative group.

Conclusions

Pollen-induced AC is caused by pollen sensitization of the conjunctiva. Food-induced AC might be induced by the different pathological mechanism involved in pollen-induced AC.

Relevance of IgE, allergy and eye rubbing in the pathogenesis and management of Keratoconus

Keratoconus (KC) is an ectatic disease of the cornea characterized by localized thinning and protrusion causing irregular astigmatism, which can lead to significant visual impairment. KC has often been associated with allergy and/or atopy, which are immune-mediated inflammatory reactions primarily driven by IgE. A higher proportion of KC patients were reported to have history or suffer from systemic and/or ocular allergy with elevated allergen-specific IgE and/or total serum IgE. Eye rubbing, one of the risk factors for worsening of the disease and developing related complications in KC, is associated with IgE driven conditions. The current review enumerates and contextualizes the evidence related to IgE in mediating KC pathogenesis, including aberrant extra-cellular matrix remodeling. This review also discusses clinical strategies directed at modulating IgE-mediated responses in the management of KC, and the emerging academic and plausible clinical relevance of assessing serum and tear IgE (allergen-specific and total) status in improving the understanding of disease pathobiology, treatment planning, and prognosis.

To See or Not to See: A Systematic Review of the Importance of Human Ocular Surface Cytokine Biosignatures in Ocular Allergy

Cytokines are key cell signalling proteins in a number of immune and homeostatic pathways of the human body. In particular, they mediate intracellular mechanisms of allergy on the ocular surface by triggering cellular responses that result in typical physiological ocular allergy symptoms, such as itchiness, watery eyes, irritation, and swelling. Given the recent research focus in optometry on the aetiology of corneal ectasia subtypes like keratoconus, there is an increasing need for the development of new clinical diagnostic methods. An increasing trend is evident among recent publications in cytokine studies, whereby the concentrations of cytokines in healthy and disease states are compared to derive a specific cytokine profile for that disease referred to as ‘biosignatures’. Biosignatures have diagnostic applications in ocular allergy as a cheap, non-invasive alternative to current techniques like IgE antibody testing and skin prick tests. Cytokine detection from tear samples collected via microcapillary flow can be analysed either by enzyme-linked immunosorbent assays (ELISA), multiplex magnetic bead assays, or immunoblot assays. Characterising patient hypersensitivities through diagnostic tests is the first step to managing exposure to triggers. Investigating cytokine biosignatures in ocular allergy and their links to physiology are imperative and will be the focus of this systematic review article.

Advances in Molecular Mechanisms of Wheat Allergenicity in Animal Models: A Comprehensive Review

The prevalence of wheat allergy has reached significant levels in many countries. Therefore, wheat is a major global food safety and public health issue. Animal models serve as critical tools to advance the understanding of the mechanisms of wheat allergenicity to develop preventive and control methods. A comprehensive review on the molecular mechanisms of wheat allergenicity using animal models is unavailable at present. There were two major objectives of this study: To identify the lessons that animal models have taught us regarding the molecular mechanisms of wheat allergenicity and to identify the strengths, challenges, and future prospects of animal models in basic and applied wheat allergy research. Using the PubMed and Google Scholar databases, we retrieved and critically analyzed the relevant articles and excluded celiac disease and non-celiac gluten sensitivity. Our analysis shows that animal models can provide insight into the IgE epitope structure of wheat allergens, effects of detergents and other chemicals on wheat allergenicity, and the role of genetics, microbiome, and food processing in wheat allergy. Although animal models have inherent limitations, they are critical to advance knowledge on the molecular mechanisms of wheat allergenicity. They can also serve as highly useful pre-clinical testing tools to develop safer genetically modified wheat, hypoallergenic wheat products, novel pharmaceuticals, and vaccines.