Evaluation of Sensitivity Toward Storage Mites and House Dust Mites Among Nasobronchial Allergic Patients of Kolkata, India

A review on aero-allergen induced allergy in India

Allergic diseases such as bronchial asthma, rhinitis and eczema are an important public health issue globally in 21st century. Their prevalence and impact in India is high, in terms of total numbers of people affected. Due to diverse climate and lifestyle, the Indian population is exposed to a rich and varied range of aerobiological particles. In the last two decades in India, 83 pollens, 34 fungi, six dust mite and 19 insect species were reported as allergenic, often contributing to heavy allergenic exposure in indoor and outdoor environments. There are currently few practitioners who offer allergy diagnosis and treatment in India, but there is active basic and molecular research aiming to improve the health of allergic patients. This review explores the field of aero-allergy in India during the last two decades, with special emphasis on prevalence across various centres and relevant scientific advances such as genetic associations and new therapeutics. This review will be helpful for clinicians to select aero-allergens for sensitisation testing in patients suffering from symptoms in different regions of India, and to support patients undertaking prophylaxis of allergic symptoms in India according to local environmental conditions. This study also helps to define patient selection for allergy testing and the role of test results in guiding allergic disease management in the Indian context. Finally, we summarize genetic findings relevant to aero-allergy in India and discuss the development of novel therapeutics for investigation and management of aero-allergy in India.

In silico analysis of single nucleotide polymorphism (rs34377097) of TBXA2R gene and pollen induced bronchial asthma susceptibility in West Bengal population, India

Introduction

Prevalence of asthma is increasing steadily among general population in developing countries over past two decades. One of the causative agents of broncho-constriction in asthma is thromboxane A2 receptor (TBXA2R). However few studies of TBXA2R polymorphism were performed so far. The present study aimed to assess potential association of TBXA2R rs34377097 polymorphism causing missense substitution of Arginine to Leucine (R60L) among 482 patients diagnosed with pollen-induced asthma and 122 control participants from West Bengal, India. Also we performed in-silico analysis of mutated TBXA2R protein (R60L) using homology modeling.

Methods

Clinical parameters like Forced expiratory volume in 1 second (FEV₁), FEV₁/Forced vital capacity (FVC) and Peak expiratory flow rate (PEFR) were assessed using spirometry. Patients' sensitivity was measured by skin prick test (SPT) against 16 pollen allergens. Polymerase chain reaction-based Restriction fragment length polymorphism was done for genotyping. Structural model of wild type and homology model of polymorphic TBXA2R was generated using AlphaFold2 and MODELLER respectively. Electrostatic surface potential was calculated using APBS plugin in PyMol.

Results

Genotype frequencies differed significantly between the study groups (P=0.03). There was no significant deviation from Hardy-Weinberg equilibrium in control population (χ2=1.56). Asthmatic patients have significantly higher frequency of rs34377097TT genotype than control subjects (P=0.03). SPT of patients showed maximum sensitivity in A. indica (87.68%) followed by C. nusifera (83.29%) and C. pulcherima (74.94%). Significant difference existed for pollen sensitivity in adolescent and young adult (P=0.01) and between young and old adult (P=0.0003). Significant negative correlation was found between FEV1/FVC ratio and intensity of SPT reactions (P<0.0001). Significant association of FEV₁, FEV₁/FVC and PEFR was observed with pollen-induced asthma. Furthermore, risk allele T was found to be clinically correlated with lower FEV₁/FVC ratio (P=0.015) in patients. Our data showed R60L polymorphism, which was conserved across mammals, significantly reduced positive electrostatic charge of polymorphic protein in cytoplasmic domain thus altered downstream pathway and induced asthma response.

Discussion

The present in-silico study is the first one to report association of TBXA2R rs34377097 polymorphism in an Indian population. It may be used as prognostic marker of clinical response to asthma in West Bengal and possible target of therapeutics in future.

Association of Interleukin 6 and Interleukin 8 genes polymorphisms with house dust mite-induced nasal-bronchial allergy in a sample of Indian patients

Background

Genetic background of nasal-bronchial allergy (NBA) is well documented. House Dust Mites (HDMs) are reported to elicit NBA symptoms. Susceptibility to HDM sensitization varies considerably from person to person. Interleukin 6 (IL 6) and Interleukin 8 (IL 8) are studied previously for genetic association with several diseases. To the best of our knowledge, the genetic association of HDM-induced NBA has not been largely reported from India. The aim of our present study was to evaluate any possible association of IL 6 and IL 8 gene polymorphisms with HDM-induced NBA in an Indian population.

Methods

IL 6 (− 572G/C, − 597G/A) and IL 8 polymorphisms (− 251A/T, + 781C/T) were analyzed in a HDM-sensitized group (N = 372) and a control group (N = 110). Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR–RFLP) based genotyping was done. Chi-square test and Fisher’s exact tests were applied for statistical analysis.

Results

IL 6 − 597G/A and IL 8 + 781C/T were not associated with HDM-sensitization, while IL 6 − 72G/C and IL 8 − 51A/T showed significant associations in terms of both genotype and allele frequencies. For both the SNPs, minor allele frequencies were significantly higher in the patients compared to the control. Moreover, IL 6 -572G/C and IL 8 -251A/T were found to be strongly linked with HDM sensitization and severity.

Conclusion

This is probably the pioneer study to describe the association of IL 6 and IL 8 polymorphisms with HDM sensitization in any Indian population. The results suggested that IL 6 -572G/C and IL 8 -251A/T may exert a risk of HDM sensitization leading to NBA.

Allergenicity assessment of fungal species using immunoclinical and proteomic techniques: a study on Fusarium lateritium

Airborne fungal spores are extensively reported as the elicitors of respiratory allergies in human. Fusarium lateritium is one such fungal species reported for eliciting significant skin prick results from India. The present study aims to analyze the allergenic potential of F. lateritium followed by the identification of allergens. The total protein of F. lateritium was subjected to 1dimensional (1D) and 2D gel electrophoresis followed by corresponding IgE-specific immunoblots. We found 8 immunoreactive bands/zones in (1D) immunoblot using 11 F. lateritium-sensitised patient sera. In 1D immunoblot, a 34 kDa band was detected in >80% of the patients and hence considered as a potential allergen of F. lateritium. Corresponding 34 kDa spot in 2D-immunoblot was analyzed by mass spectrometric analysis and identified as Glyceraldehyde 3-phosphate dehydrogenase. The identified F. lateritium allergen holds the potential to instigate vaccine development for immunotherapy of F. lateritium sensitized patients.

Expression, epitope prediction and IgE-binding of the Tyrophagus putrescentiae group 13 allergen

Storage mites, such as Tyrophagus putrescentiae, are an important source of allergens that cause allergic diseases in humans. It has previously been indicated that T. putrescentiae has a high sensitization rate as an allergen in some Asian and European countries. Identifying and cloning the allergens in this species may enable improved diagnostic and therapeutic approaches. The aim of the present study was to clone and sequence the T. putrescentiae group 13 allergen (Tyr p 13) isolated from storage mites in China, to use bioinformatics tools to model its biophysical characteristics and to induce protein expression to test its IgE-binding activity. The full-length cDNA comprised 486 bp and was predicted to include a signal peptide of 22 amino acids. Its secondary structure was shown to comprise an α-helix (10.79%), extended strand (33.81%) and random coils (55.40%). Using homology modeling, the present study constructed a reasonable tertiary structure of Tyr p 13. Linear Bcell epitopes at amino acids 47-53, 70-76, 81-86, 101-105 and 112120 were predicted. Three discontinuous B-cell epitopes were also predicted: i) 47, 48, 49, 50, 51, 52, 53, 70, 71, 72 and 73; ii) 91, 92, 93, 94, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 and 138; and iii) 74, 76, 79, 81, 82, 83, 84, 86, 101, 102, 103, 104 and 105. SDS-PAGE identified a specific band at the predicted molecular weight of the recombinant Tyr p 13 (rTyr p 13), demonstrating its successful expression. The rTyr p 13 bound to IgE in the serum of 13.2% (5/38) of patients allergic to T. putrescentiae, according to ELISA. The successful cloning of Tyr p 13 and basic bioinformatics analysis of the protein provided a foundation for the further study of this allergen with regards to the diagnosis and treatment of patients allergic to storage mites. These results provided a theoretical basis for the design of rTyr p 13 with modified B-cell epitopes.

A review of house dust mite allergy in India

House dust mites (HDMs) are extensively reported as potent allergens worldwide with India being in the top row. HDM sensitization is hugely reported from India and has led to the concern of implementing proper guidelines for treatment of the sufferers. Climatic conditions and a rapid shift of life style toward a more indoor and urbanised pattern are denoted as the probable causes of increased HDM exposure and sensitization. On the contrary, the varying rate of HDM allergy from similar climate and urbanised areas throughout the world suggest the influence of genetic predisposition. At present, in India, avoidance of HDM exposure is recommended as the baseline defence. Allergen immunotherapy (AIT) guidelines are proposed in India to maintain uniformity in the diagnosis techniques and management strategies throughout the country. Considering the genetic susceptibility toward allergic diseases, the concept of 'personalised medicine' is preferred over the 'mass targeted treatment'. From the Indian perspective, the present problem is Dermatophagoides pteronyssinus and D. farinae allergens are not well characterised at the molecular level. As a consequence, India is still reliant on less standardised allergen extracts. The proper identification, purification, and molecular characterization of HDM allergens can combat this problem. In this review, we aimed to portray a complete account of HDM allergy in India with respect to prevalence, probable triggers, diagnosis and therapy. We have attempted to present the current ambiguities along with the likely deciphering that would pave the way to solve HDM allergy-related queries in India.