Debajyoti Ghosh

Bronchial smooth muscle remodeling involves calcium-dependent enhanced mitochondrial biogenesis in asthma

Asthma and chronic obstructive pulmonary disease (COPD) are characterized by different patterns of airway remodeling, which all include an increased mass of bronchial smooth muscle (BSM). A remaining major question concerns the mechanisms underlying such a remodeling of BSM. Because mitochondria play a major role in both cell proliferation and apoptosis, we hypothesized that mitochondrial activation in BSM could play a role in this remodeling. We describe that both the mitochondrial mass and oxygen consumption were higher in the BSM from asthmatic subjects than in that from both COPD and controls. This feature, which is specific to asthma, was related to an enhanced mitochondrial biogenesis through up-regulation of peroxisome proliferator-activated receptor γ coactivator (PGC)–1α, nuclear respiratory factor-1, and mitochondrial transcription factor A. The priming event of such activation was an alteration in BSM calcium homeostasis. BSM cell apoptosis was not different in the three groups of subjects. Asthmatic BSM was, however, characterized by increased cell growth and proliferation. Both characteristics were completely abrogated in mitochondria-deficient asthmatic BSM cells. Conversely, in both COPD and control BSM cells, induction of mitochondrial biogenesis reproduced these characteristics. Thus, BSM in asthmatic patients is characterized by an altered calcium homeostasis that increases mitochondrial biogenesis, which, in turn, enhances cell proliferation, leading to airway remodeling.

Aerobiological and immunochemical studies on Carica papaya L. pollen: an aeroallergen from India

Background:  Carica papaya L. is a fruit yielding tree, wildly grown or cultivated in the tropics and subtropics. Its pollen grain has been reported to be airborne and cause immunoglobulin E (IgE)‐mediated hypersensitivity.

Cyanobacteria: an unrecognized ubiquitous sensitizing allergen?

This study was designed to investigate the prevalence of skin sensitization using detoxified cyanobacterial reagents in a chronic rhinitis population. Subjects ≥6 years of age who presented for allergy consultation to a community allergy practice and required skin-prick testing (SPT) to common seasonal and perennial aeroallergens were enrolled after signing an informed consent. Detoxified cyanobacteria species were used for skin testing. Skin testing of unexposed, nonsensitized control subjects using these detoxified cyanobacterial skin test reagents was performed to identify irritant threshold responses. All subjects signed an Institutional Review Board-approved informed consent before participation. Two hundred fifty-nine patients ranging in age between 7 and 78 years old underwent testing. The majority were white female patients and over two-thirds (73.4%) were atopic. Seventy-four (28.6% of the population) patients were SPT(+) to at least one of the cyanobacteria species. Positive SPTs were present in 86% of patients to Microcystis aeruginosa and 12% of patients to Aphanizomenon-flos aquae. There was a strong association between severity of atopy (number of positive SPTs), having allergic rhinitis and sensitization to one or more cyanobacteria species (p < 0.001). This is the first study to show that cyanobacterial allergenicity resides in nontoxin-containing components of this organism.

Asthma-related hospital admissions in an Indian megacity: role of ambient aeroallergens and inorganic pollutants.

Environmental pollution is a serious problem in rapidly developing countries like China and India (1), the latter being projected to become the world’s most populous nation by the year 2050. India is also the home to around 15–20 million asthmatics; the number is steadily increasing, mainly in the cities like Kolkata (formerly known as Calcutta; 22 33¢N 88 20¢E). Asthma accounts for significant economic burden worldwide, much of which is related to the episodes of exacerbation leading to hospital admissions. The objective of this pilot study was to understand the seasonality of Asthma-related hospital admissions (ARHA) in the megacity of Kolkata in relation to ambient biological and inorganic factors. ARHA data were collected from Nilratan Sircar Medical College and Hospital, an apex hospital of the city, which is equipped with emergency medical care facilities and represents a significant portion of total ARHA in Kolkata. Airborne pollen and spore load were recorded with a burkard 7day sampler following aerobiological methods described elsewhere (2, 3), while concentrations of air pollutants SO2, NO2, suspended particulate matter (SPM) and respirable particulate matter (RPM) were recorded and made available by the West Bengal Pollution Control Board. For statistical analyses, pollen, spore and pollutant levels were considered as predictor variables, while ARHA was taken as the outcome variable. Data were recorded over a 5-years period in 10-day time slots. Poisson regression, with and without correction for overdispersion, was used to model the data using the Statistical Analysis System (sas Version 9.1, SAS Inc., Cary, NC, USA). All P-values below 0.05 were considered significant. Concordant to a previous observation (4), we found that ARHA in Kolkata follows a bimodal distribution, with the highest number of cases (per 10-day time period) being observed in March (17.33 ± 1.3) and September (17.83 ± 2.01). In fact, more than 40% of annual ARHA occurs just during these 2 months. The numbers are low in mid-January (1.50 ± 0.43) and in midJuly (2.17 ± 0.40). Consistency of this seasonal pattern, along with the amplitude of the peaks in relation to the rest of the yearly cycle, suggests the presence of one or more consistent factor(s) influencing asthma exacerbation. First, we carried out the Poisson Generalized Linear Model (GLM) analysis (5) considering only biological factors (airborne allergenic pollen and spore). We calculated the regression coefficients for each variable and the corresponding Chi-square statistics with P-values and found that the pollens Areca, Carica, Cheno-Amaranthaceae and Cyperaceae are positively associated with ARHA. We corrected overdispersion in the Poisson model by estimating a dispersion parameter based on quasi-likelihood approach and adjusted the standard errors of the regression coefficients based on this estimated dispersion parameter. After correcting overdispersion, Areca, Cheno-Amaranthaceae and Cyperaceae remained significantly associated with the number of ARHA. Next, we included the pollutants’ data in the said model and found that when pollutants are taken into account, the pollens Areca, Cheno-Amaranthaceae, Cyperaceae and Poaceae showed Asthma-related hospitalization in an Indian megacity exhibits seasonal bias chiefly governed by airborne pollen and respirable particulate matter. Table 1 Result of regression analyses using Poisson GLM with ARHA as the independent variable, while pollen, spore and pollutants as dependent variables

Homology modeling of allergenic cyclophilins: IgE-binding site and structural basis of cross-reactivity

Cross-reactivity among allergens is of considerable scientific as well as clinical interest. Proteins belonging to the allergenic cyclophilin family share a high degree of sequence homology and are cross-reactive. Until date no three-dimensional structural information is available on these proteins and the shared structural features of the epitopes which are the most important determinants of cross-reactivity. Cyclophilins are also known to bind with the immuno-suppressive drug cyclosporin. Comparative molecular modeling of these allergenic cyclophilin proteins of different sources was performed in order to investigate the structural basis of their cross-reactivity. All the proteins studied revealed a similarity in the shape of the cross-reactive epitopes with varying degrees of accessibility. Cyclosporin binding and allergenic properties of these proteins were also found to be structurally related.

Systemic and localized seminal plasma hypersensitivity patients exhibit divergent immunologic characteristics

In conclusion, this study indicates that several conformational epitopes on Jun a 1 are major targets for the IgE response to mountain cedar pollen. This finding suggests that these antibodies are produced in the upper airway after exposure to inhaled, native Jun a 1. This makes Jun a 1 an excellent candidate for the development of new approaches for preventing allergic reactions. Thesemight entail the development of agents that selectively alter the display of dominant epitopes, which may impede epitope spreading. On a more basic level, our findings are consistent with the concept that allergens, as a group, share a relatively small number of structures, which, along with other factors, such as their abundance and stability in the human environment, make them unique among proteins. The characteristics of the allergic response to mountain cedar pollen also make Jun a1 an excellent prototype for identifying the structural basis of allergenicity.

Associations between Pollen Counts, Pollutants, and Asthma-Related Hospital Admissions in a High-Density Indian Metropolis

Background. The seasonal pattern of asthma-related hospitalization has often been correlated with ambient allergen/pollutant levels. Objective. To examine the relationship between asthma-related hospital admissions (ARHA) and outdoor pollen, spore, and pollutant levels for adult patients in a densely populated Indian megacity Kolkata. Methods. ARHA data were obtained from two major teaching hospitals of the city. Pollen and spores causing allergic sensitization were identified by skin prick tests (SPTs) among respiratory allergic subjects (N = 1353). Outdoor concentrations of aeroallergens were determined using a Burkard sampler for five consecutive years (2004–2009). Levels of NO2, SO2, suspended particulate matters (SPMs), and respirable particulate matters (RPMs) were made available by West Bengal Pollution Control Board (WBPCB, Government of West Bengal). Poisson multivariate Poisson regression (with adjustments for overdispersion) was used to model the data. Results. We found that ARHA in Kolkata increased with predictable regularity in March and September, while remaining low in January and July. SPT showed highly positive skin reactions with grass/weed and palm pollens in respiratory allergic patients, while Aspergilli spores also evoked good sensitivity. In our regression model, the airborne pollen types, Cheno-Amaranthaceae and Cyperaceae, and the inorganic pollutant, SO2 and RPM, were significantly associated with ARHA (p < .05). Conclusion. ARHA in the megacity of Kolkata shows two seasonal peaks that can be correlated with outdoor grass/weed pollen and RPM concentrations. In contrast, the city’s ambient fungal spore counts were not found to be significantly associated.

Identification of Microcystis aeruginosa Peptides Responsible for Allergic Sensitization and Characterization of Functional Interactions between Cyanobacterial Toxins and Immunogenic Peptides

Background The cyanobacterium species Microcystis aeruginosa produces microcystin and an array of diverse metabolites believed responsible for their toxicity and/or immunogenicity. Previously, chronic rhinitis patients were demonstrated to elicit a specific IgE response to nontoxic strains of M. aeruginosa by skin-prick testing, indicating that cyanobacteria allergenicity resides in a non-toxin–producing component of the organism. Objectives We sought to identify and characterize M. aeruginosa peptide(s) responsible for allergic sensitization in susceptible individuals, and we investigated the functional interactions between cyanobacterial toxins and their coexpressed immunogenic peptides. Methods Sera from patients and extracts from M. aeruginosa toxic [MC(+)] and nontoxic [MC(–)] strains were used to test IgE-specific reactivity by direct and indirect ELISAs; 2D gel electrophoresis, followed by immunoblots and mass spectrometry (MS), was performed to identify the relevant sensitizing peptides. Cytotoxicity and mediator release assays were performed using the MC(+) and MC(–) lysates. Results We found specific IgE to be increased more in response to the MC(–) strain than the MC(+) strain. This response was inhibited by preincubation of MC(–) lysate with increasing concentrations of microcystin. MS revealed that phycocyanin and the core-membrane linker peptide are the responsible allergens, and MC(–) extracts containing these proteins induced β-hexosaminidase release in rat basophil leukemia cells. Conclusions Phycobiliprotein complexes in M. aeruginosa have been identified as the relevant sensitizing proteins. Our finding that allergenicity is inhibited in a dose-dependent manner by microcystin toxin suggests that further investigation is warranted to understand the interplay between immunogenicity and toxicity of cyanobacteria under diverse environmental conditions. Citation Geh EN, Ghosh D, McKell M, de la Cruz AA, Stelma G, Bernstein JA. 2015. Identification of Microcystis aeruginosa peptides responsible for allergic sensitization and characterization of functional interactions between cyanobacterial toxins and immunogenic peptides. Environ Health Perspect 123:1159–1166; http://dx.doi.org/10.1289/ehp.1409065

Is Trimellitic Anhydride Skin Testing a Sufficient Screening Tool for Selectively Identifying Tma-exposed Workers With Tma-specific Serum Ige Antibodies?

Objective: Trimellitic anhydride (TMA) can elicit specific IgE-mediated immune responses leading to asthma. This single-blinded study investigated the ability of TMA skin testing to identify workers with TMA-serum specific IgE antibodies. Methods: Forty TMA-exposed workers who were previously screened for the presence of TMA-IgG and/or IgE serum specific antibodies were skin tested to a TMA–human serum albumin reagent by nurses blinded to their antibody responses. Results: Findings from skin-prick tests were positive in 8 of 11 workers with TMA-serum specific IgE antibodies. Intracutaneous testing, performed only on skin prick testing–negative workers, was positive in two additional workers with TMA-serum specific IgE antibodies. A significant correlation was found between serum and skin test dilutions eliciting positive responses (&rgr; = 0.87, P < 0.05; n = 11). Conclusions: TMA skin testing provides an alternative and potentially more practical method for monitoring TMA-exposed workers for developing IgE sensitization.

Retinoic acid prevents immunogenicity of milk lipocalin Bos d 5 through binding to its immunodominant T-cell epitope

The major cow’s milk allergen Bos d 5 belongs to the lipocalin protein family, with an intramolecular pocket for hydrophobic ligands. We investigated whether Bos d 5 when loaded with the active vitamin A metabolite retinoic acid (RA), would elicit differential immune responses compared to the unloaded state. By in silico docking an affinity energy of −7.8 kcal/mol was calculated for RA into Bos d 5. Loading of RA to Bos d 5 could be achieved in vitro, as demonstrated by ANS displacement assay, but had no effect on serum IgE binding in tolerant or challenge-positive milk allergic children. Bioinformatic analysis revealed that RA binds to the immunodominant T-cell epitope region of Bos d 5. In accordance, Bos d 5 significantly suppressed the CD3+ CD4+ cell numbers, proliferative response and IL-10, IL-13 and IFN-γ secretion from stimulated human PBMCs only when complexed with RA. This phenomenon was neither associated with apoptosis of T-cells nor with the activation of Foxp3+ T-cells, but correlated likely with enhanced stability to lysosomal digestion due to a predicted overlap of Cathepsin S cleavage sites with the RA binding site. Taken together, proper loading of Bos d 5 with RA may suppress its immunogenicity and prevent its allergenicity.