Immunopathogenesis of allergic disorders: current concepts

Ocular surface sphingolipids associate with the refractory nature of vernal keratoconjunctivitis: newer insights in VKC pathogenesis

BACKGROUND

The etiopathogenesis of vernal keratoconjunctivitis (VKC) is incompletely understood. Bioactive lipids play a key role in allergic disorders. This study focused on the sphingolipid metabolism on the ocular surface of VKC and to explore if it has a contributory role in the refractoriness of the disease.

METHODS

Active VKC cases, (n=87) (classified as mild/moderate and severe/very severe based on the disease symptoms) and age-matched healthy controls (n=60) were recruited as part of a 2-year prospective study at a tertiary eye care centre in South India. Conjunctival imprint cytology was used to assess gene expression of enzymes of sphingolipids metabolism. Sphingolipids were estimated in the tears by LC-MS/MS analysis. In vitro study was done to assess IgE-induced alterations in sphingosine-1-phosphate (S1P) receptor expression and histone modification in cultured mast cells.

RESULTS

Significantly altered gene expression of the sphingolipids enzymes and S1P receptor (SIP3R) were observed in conjunctival imprint cells of VKC cases. Pooled tears analysis revealed significantly lowered levels of S1P(d17:0), S1P(d20:1) (p<0.001) and S1P(d17:1) (p<0.01) specifically in severe/very severe VKC compared with both mild/moderate VKC and control. Cer(d18:/17:0) (p<0.001), ceramide-1-phosphate (C1P)(d18:1/8:0) (p<0.01) and C1P(d18:1/2.0 (p<0.05) were lowered in severe/very severe VKC compared with mild/moderate VKC. Cultured mast cells treated with IgE revealed significantly increased gene expression of S1P1 and 3 receptors and the protein expression of histone deacetylases (1, 6).

CONCLUSION

Altered sphingolipid metabolism in the ocular surface results in low tear ceramide and sphingosine levels in severe/very severe VKC compared with the mild/moderate cases. The novel finding opens up fresh targets for intervention in these refractory cases.

α-Linolenic Acid Screened by Molecular Docking Attenuates Inflammation by Regulating Th1/Th2 Imbalance in Ovalbumin-Induced Mice of Allergic Rhinitis

α-Linolenic acid (ALA) is a natural essential fatty acid widely found in plant seed oils and beans, which shows positive anti-inflammatory and antiallergic effects. In our previous study, ALA was proven to bind tightly to the seven protein targets closely associated with allergic rhinitis (AR) by molecular docking, which indicates that ALA may have a potential role in the treatment of AR. A mouse model of AR induced by ovalbumin (OVA) was adopted in this study to explore the therapeutical effect and potential mechanism of ALA in treating AR. Results demonstrated that ALA remarkably relieved the nasal symptoms, reduced the OVA-sIgE level in the serum, relieved the histopathological injuries, and downregulated the mRNA expression levels of IL-6 and IL-1β in the nasal mucosa. ALA also remarkably moderated the imbalance of Th1/Th2 cells, increased the mRNA expression levels of T-bet and STAT1, and reduced GATA3 and STAT6. ALA was proven to have a substantial therapeutic effect on mice with AR, and the underlying mechanism was likely to be the regulation of Th1/Th2 imbalance through the JAK/T-bet/STAT1 and JAK/GATA3/STAT6 pathways. This study provides a specific experimental basis for the clinical use and drug development of ALA in the treatment of AR.

Amelioration of Ovalbumin-Induced Allergic Asthma by Juglans regia via Downregulation of Inflammatory Cytokines and Upregulation of Aquaporin-1 and Aquaporin-5 in Mice

Juglans regia (J. regia) has been used traditionally to treat cough and asthma. The present study evaluates the immunomodulatory and anti-inflammatory potential of J. regia against ovalbumin (OVA)-induced allergic asthma. Intraperitoneal sensitization proceeded by intranasal challenge with OVA was used to induce allergic asthma. BALB/c mice were treated with methanol, n-hexane, and ethyl acetate extracts of J. regia and methylprednisolone one week after 2^nd sensitization with OVA and continued for 7 days. mRNA expression levels of IL-4, IL-5, IL-13, AQP-1, AQP-5 TNF-α, TGF-β, and NF-kB were determined using reverse transcription polymerase chain reaction. Hematoxylin and eosin, and periodic acidic-Schiff stains were used for histopathological studies of lung tissues. The data presented all three extracts of J. regia significantly ameliorated airway inflammation by reducing expression levels of IL-4, IL-5, and IL-13 and TNF-α in OVA-treated mice. The suppression of goblet cells hyperplasia and inflammatory cells infiltration by J. regia involved low TGF-β and NF-kB levels. Pretreatment with J. regia also increased the AQP-1 and AQP-5 expression levels in mice treated with OVA. This study supported the traditional use of J. regia and proposed that J. regia ameliorated allergic asthma by suppression of proinflammatory cytokines and elevation of AQP-1 and AQP-5 expression levels.

The prevalence of allergic diseases in school children of metropolitan city in Indonesia shows a similar pattern to that of developed countries

Background

The prevalence of allergy among Surabaya school children is currently unknown.

Objective

To identify the prevalence of the common allergic sensitization and allergic diseases among school children and undergraduate students in suburban of Surabaya by epidemiologic data collection.

Methods

A multistage simple random sampling was done to select 5 primary schools, 8 secondary schools (4 of junior high schools and senior high schools, respectively), and 1 university from 5 districts in Surabaya city. Out of 550 invited respondents, 499 (128 primary school, 221 secondary school, and 150 undergraduate) respondents gave their consent. A complete personal history, allergic symptoms, environmental exposure of common allergens was obtained from interview and the physical examinations were performed. Skin prick test (SPT) was done using 45 different allergen extracts. Total serum IgE and specific IgE radioallergosorbent test levels were measured for respondents with allergic manifestations.

Results

There was an increasing SPT positivity among study respondents, from primary school, secondary school, to undergraduate students (21.90%, 28.95%, to 45.30% respectively). Cockroach (42.85%) and fungi/mold spore (42.85%) were the most common allergens in primary school children. House dust mites was the most common allergen in secondary school (63.16%) and undergraduate students (58.82%). Urticaria and rhinitis were the commonest allergic diseases manifestation. History of atopy was positive in 60.79% of the allergic respondents.

Conclusion

The prevalence of allergic sensitization among school children and undergraduate students in Surabaya suburb areas were increased compared to previous estimates in 1998. While house dust mites are known as important allergens, surprisingly cockroach was the common allergen among the younger school children.

GENETIC AND ENVIRONMENTAL FACTORS AS STRONG DETERMINANTS OF ATOPIC ALLERGIC DISEASE CLINICAL MANIFESTATIONS IN SURABAYA'S SCHOOL CHILDREN

This case-control study was conducted to assess the relative role of genetic and environmental factors in determining the clinical manifestations of atopy allergy disease in school children, which is part of a large study of the prevalence of allergic diseases in school children in Surabaya. Using a simple multi-stage random sampling, 348 children from 5 elementary schools, 4 junior high schools, and 4 senior high schools in Surabaya were involved in the study. The subjects of the study along with her parents were guided to fill out the modified ISAAC questionnaire and underwent physical examination and skin prick test using 27 common allergen types found in the environment. For the analysis, 110 school children were randomly selected from the parent sample and included in the case group of 55 people (positive skin prick test against > 1 type of allergen), and the control group of 55 people (negative skin prick test). All genetic and environmental factors data were collected and analyzed. Most of the subjects had clinical manifestations of allergic rhinitis (66.36%), asthma (21.82%), food allergies (10.9%), and atopic dermatitis (6.36%). Complete models for multiple logistic regression analysis can only be performed for overall atopic disease and allergic rhinitis disease. The first birth order and exposure to home dust mites were the most significant clinical manifestations of atopy disease (OR 4.548, 95% CI: 1.813-11.410, p=0.01). Atopy status of the father was the only significant determinant factor for the manifestation of allergic rhinitis in the study subjects (OR 3.929; 95% CI: 1.143-13.052, p=0.03). Both genetic and environmental factors interacted and determined clinical manifestations of atopy allergy disease in school pupils. The father's genetic factors were more dominant than maternal genetic factors in determining the clinical manifestations of allergic rhinitis in offspring.

Effects of chelidonic acid, a secondary plant metabolite, on mast cell degranulation and adaptive immunity in rats

The present study evaluated the immunomodulatory effects of chelidonic acid, a secondary plant metabolite, with therapeutic potential in allergic disorders, in experimental animals. In mast cell degranulation studies, ovalbumin immunized and challenged rats, chelidonic acid (1, 3 and 10mg/kg, i.p.) dose relatedly prevented ovalbumin challenge induced mast cell degranulation by differing degrees when compared with vehicle treated group, and these effects were comparable with prednisolone (10mg/kg). A reduction in post-challenge mortality was also observed in all treated groups. Further, there were reductions in the blood eosinophil counts and serum IgE levels after chelidonic acid treatment. Chelidonic acid also inhibited histamine release from rat peritoneal mast cells (RPMC) in vitro, in a dose related manner. In tests for adaptive immunity, in rats immunized with sheep RBC, chelidonic acid differentially suppressed the (a) plaque forming cell (PFC) count in rat splenic cells, (b) anti-SRBC antibody titre and serum IgG levels and (c) increases in foot pad thickness in the DTH assay - all of which were comparable with prednisolone. These experimental results are discussed in light of the possible therapeutic potential of chelidonic acid in allergic disorders.

Treatment of allergic rhinitis and urticaria: a review of the newest antihistamine drug bilastine

Allergic rhinitis and urticaria are common allergic diseases that may have a major negative impact on patients' quality of life. Bilastine, a novel new-generation antihistamine that is highly selective for the H1 histamine receptor, has a rapid onset and prolonged duration of action. This agent does not interact with the cytochrome P450 system and does not undergo significant metabolism in humans, suggesting that it has very low potential for drug-drug interactions, and does not require dose adjustment in renal impairment. As bilastine is not metabolized and is excreted largely unchanged, hepatic impairment is not expected to increase systemic exposure above the drug's safety margin. Bilastine has demonstrated similar efficacy to cetirizine and desloratadine in patients with seasonal allergic rhinitis and, in a Vienna Chamber study, a potentially longer duration of action than fexofenadine in patients with asymptomatic seasonal allergic rhinitis. It has also shown significant efficacy (similar to that of cetirizine) and safety in the long-term treatment of perennial allergic rhinitis. Bilastine showed similar efficacy to levocetirizine in patients with chronic spontaneous urticaria and can be safely used at doses of up to fourfold higher than standard dosage (80 mg once daily). The fourfold higher than standard dose is specified as an acceptable second-line treatment option for urticaria in international guidelines. Bilastine is generally well tolerated, both at standard and at supratherapeutic doses, appears to have less sedative potential than other second-generation antihistamines, and has no cardiotoxicity. Based on its pharmacokinetic properties, efficacy, and tolerability profile, bilastine will be valuable in the management of allergic rhinitis and urticaria.

The evolution of allergen and non-specific immunotherapy: past achievements, current applications and future outlook

Recent epidemiological studies estimated that more than 30% of European suffer from allergic rhinitis or conjunctivitis, while up to 20% suffer from asthma and 15% from allergic skin conditions, while for many other regions the prevalence is increasing. Allergen immunotherapy represents the only available treatment that can modify the allergic disease process, and thus is worth considering as a treatment in affected individuals. A beneficial effect of allergen immunotherapy has been shown in both adults and children affected by allergic rhinitis, allergic conjunctivitis, allergic asthma and hymenoptera venom allergy. The present study represents an overview on allergen immunotherapy, focusing on the principal aspects of the use of immunotherapy in the past, its recent clinical applications and future outlook.