Cockroach Allergy Research Articles

Sequence Polymorphisms of Major German Cockroach Allergens Bla g 1, Bla g 2, Bla g 4, and Bla g 5

Background: The allergenicity of allergens could be influenced by amino acid substitutions in B- or T-cell epitope regions. The German cockroach is known to produce potent allergens inducing strong IgE-mediated allergic reactions. This study was performed to investigate sequence variations in major allergens of the German cockroach. Methods: Reverse transcriptase PCR was used to amplify the cDNA sequences encoding major allergens of the German cockroach (Bla g 1, Bla g 2, Bla g 4, and Bla g 5). Results: The deduced amino acid sequences revealed 38 Bla g 1 variants with 1–7 amino acid substitutions (98.6–99.8% identity), 28 Bla g 2 variants with 1–3 substitutions (99.1–99.7%), 27 Bla g 4 variants with 0–32 substitutions (82.4–100%), and 8 Bla g 5 variants with 1–2 substitutions (99.0–99.5%), respectively. Bla g 1 and Bla g 2 showed sporadic amino acid substitutions despite the divergence in their sequences. Bla g 4 exhibited frequent variations, with clusters of substitutions in residues 29–38, 52–80, and 132–155. Sequence variations in Bla g 4 imply the presence of multiple isoforms and isoallergens, which may in turn have various effects on the IgE-binding capacity and T-cell responsiveness. Only 8 variants were found in Bla g 5, with infrequent amino acid changes of one or two residues. Conclusions: Analyses of T-cell and IgE-binding epitope regions would clarify the effect of sequence polymorphisms on allergenicity, which in turn will aid in the design of allergen formulations for diagnosis and immunotherapy for cockroach allergies.

Biological potency of German cockroach allergen extracts determined in an inner city population

Cockroach allergy is an important cause of inner city asthma. To perform valid studies on the diagnosis and treatment of cockroach allergy, biological potencies of test extracts need to be established, and a surrogate in vitro test for biological potency should be chosen. Sixty-two cockroach-allergic adult subjects were recruited for quantitative skin testing with three commercial German cockroach extracts. The intradermal D50 values were determined using linear interpolation, and the biologic potencies were determined from D50 data. The extracts were also analysed for relative potency, using a competition ELISA, and for specific allergen content, using a two-site ELISA. Estimates of each extract's D50 were analysable in 48-55 subjects, with D50s between 10.3 and 11.8. All three extracts were bioequivalent using pre-set criteria. The biological potencies of the extracts were 1738-8570 bioequivalent allergy units (BAU)/mL (geometric mean=3300), and these relative potencies were similar to those estimated by competition ELISA and specific allergen content. IgE against cockroach allergens were detected in sera from 34 subjects with analysable D50s, and 17 subjects had IgE directed against specific cockroach allergens. Although the presence of anti-Bla g 5 correlated with the subjects' skin test responses for 2/3 extracts, no single allergen was immunodominant. Antibody responses among the subjects were heterogeneous. Although commercial cockroach extracts are relatively low in potency, immunotherapeutic doses should be achievable. Biological potency may be estimated using D50 testing, a combination of specific allergen determinations, or by an overall potency assay such as the competition ELISA. The biological potency of three German cockroach allergen extracts, determined in an inner city population, was 1738-8570 BAU/mL. No one allergen was immunodominant, and surrogate in vitro testing methods were examined.

Purification and cloning of a Delta class glutathione S‐transferase displaying high peroxidase activity isolated from the German cockroach Blattella germanica

A highly active glutathione S-transferase was purified from adult German cockroaches, Blattella germanica. The purified enzyme appeared as a single band of 24 kDa by SDS/PAGE, and had a different electrophoretic mobility than, a previously identified Sigma class glutathione S-transferase (Bla g 5). Kinetic study of 1-chloro-2,4-dinitrobenzene conjugation revealed a high catalytic rate but common substrate-binding and cosubstrate-binding affinities, with V(max), k(cat), K(m) for 1-chloro-2,4-dinitrobenzene and K(m) for glutathione estimated to be 664 micromol x mg(-1) x min(-1), 545 s(-1), 0.33 mm and 0.76 mm, respectively. Interestingly, this enzyme possessed the highest activity for cumene hydroperoxide among insect glutathione S-transferases reported to date. Along with the ability to metabolize 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane and 4-hydroxynonenal, this glutathione S-transferase may play a role in defense against insecticides as well as oxidative stress. On the basis of the amino acid sequences obtained from Edman degradation and MS analyses, a 987-nucleotide cDNA clone encoding a glutathione S-transferase (BggstD1) was isolated. The longest ORF encoded a 24 614 Da protein consisting of 216 amino acid residues. The sequence had close similarities ( approximately 45-60%) to that of Delta class glutathione S-transferases, but had only 14% identity to Bla g 5. The putative amino acid sequence contained matching peptide fragments of the purified glutathione S-transferase. ELISA showed that BgGSTD1 bound to serum IgE obtained from patients with cockroach allergy, indicating that the protein may be a cockroach allergen.

Addressing issues of asthma in inner-city children

For children living in the inner city, asthma tends to be more frequent and severe. Although the causes for this heightened severity of asthma are not clearly established, environmental allergens likely play a major role. To characterize, understand, and treat children with asthma living in the inner city better, the National Institutes of Allergy and Infectious Diseases of the National Institutes of Health established an Inner City Asthma Program in 1991. Over the past 15 years, 3 separate inner-city asthma research networks have been formed and funded by this institute. The work from these programs has led to important observations including evidence that environmental allergens, particularly cockroach, are important for sensitization and severity of asthma of the affected children. Furthermore, reductions in the allergen load can lead to improved asthma control. The most recent program, the Inner City Asthma Consortium, was formed in 2002 with a goal to develop immune-based therapy for children with asthma in the inner city and to determine mechanisms of these therapies as well as immunopathogenesis of asthma in these high-risk children. This article reviews these programs and how they have begun the effort to understand and treat children with asthma who live in inner cities better and what their findings mean in relationship to unique features of asthma in inner city children.

Cockroach allergy: risk factor for asthma severity

Cockroach allergy: risk factor for asthma severity

Cockroach allergy: risk factor for asthma severity - Authors' reply

Cockroach allergy: risk factor for asthma severity - Authors' reply

Use of the skin prick test and specific immunoglobulin E for the diagnosis of cockroach allergy

To compare the prevalence of allergy to cockroaches (Blattella germanica and Periplaneta americana) in asthmatic and non-asthmatic children and to determine the degree of agreement between the skin prick test and serum specific IgE levels, as well as to establish the relationship between cockroach allergy and total IgE levels. A case-control study involving 76 asthmatic and 42 non-asthmatic children aged between 6 and 14 years was conducted in Recife, Brazil. All individuals were submitted to the skin prick test and to the measurement of specific IgE for B. germanica and P. americana, as well as to the determination of total IgE concentration. Asthmatic children showed a higher frequency of positive skin reactions to B. germanica (27.6 vs. 4.8%) and P. americana (27.6 vs. 2.4%) than non-asthmatic ones. The agreement between the skin prick test and the specific IgE results was reasonable for B. germanica (kappa = 0.25) and weak for P. americana (kappa = 0.17). Those patients who tested positive for cockroaches had a significantly higher geometric mean for total IgE than those who tested negative. The agreement between specific IgE and the skin prick test increased as total IgE levels rose, although some skin tests were negative even when total IgE levels were as high as 5000 kU/l. All determinations of cockroach-specific IgE were positive for total IgE levels greater than 2500 kU/l, even among asymptomatic patients. Allergic sensitivity to cockroaches was a predictive factor for asthma severity. The skin prick test is more appropriate for the detection of clinically relevant sensitivity to cockroaches than specific IgE determination.

Bla g 6: A troponin C allergen from Blattella germanica with IgE binding calcium dependence

The known cockroach allergens do not appear to account for the full repertoire of IgE responses. To identify and investigate the importance of other Blattella germanica allergens contributing to cockroach allergy. A B germanica cDNA library was screened with pooled sera from patients with cockroach allergy. Three isoallergens of troponin C (Bla g 6) were cloned and expressed in Pichia pastoris. Homology modeling was performed by using Swiss-Model. IgE responses to purified allergens were simultaneously measured in 104 sera by using a fluorescent multiplex array system. The effect of calcium on IgE binding was investigated by ELISA. Three isoallergens, Bla g 6.0101, Bla g 6.0201, and Bla g 6.0301, were identified which share homology with insect troponin Cs and vertebrate calmodulins (61% to 78% and 42% to 44% amino acid identity, respectively) and have 2 EF-hand calcium binding domains. Molecular models of Bla g 6 showed 2 structurally homologous lobes connected by a linker that confers flexibility to the allergen. The prevalence of IgE binding to recombinant Bla g 6 was 14%. Calcium depletion by 10 mmol/L ethyleneglycol-bis-(beta-aminoethylether)-N,N,N',N'-tetraacetic acid did not significantly affect IgE binding in most cases. Interestingly, addition of 10 mmol/L CaCl2 after calcium depletion increased IgE binding by approximately 2-fold, a finding not previously reported for calcium binding allergens. Bla g 6 is a troponin allergen with a calcium dependent IgE reactivity that may be involved in muscle contraction. Bla g 6 homologous allergens may occur among other insects and cause cosensitization or allergenic cross-reactivity.

Recombinant Allergens for Diagnosis and Immunotherapy of Allergic Disorders, with Emphasis on Cockroach Allergy

The prevalence of allergic disorders has increased over the past few decades and the quality of life has been significantly influenced at least for the allergic subjects. Allergen avoidance is thought to be the best way of preventing clinical manifestation of the disease, however, it is not possible for some allergens, and other pharmacological and/or immunological treatment has to be made. Repetitive injection of sensitized allergens to the patients (immunotherapy) is the only known curative approach to the disease even though the exact mechanism is not clear to date. Crude extract of allergens has lots of shortcomings which might arouse unexpected results. Genetic engineering and recombinant allergens are thought to be one of the alternative ways to overcome these limitations. Genetic engineering could facilitate the investigation of immune responses of the subjects especially on B cell and T cell epitopes, and produce the therapeutic allergens which might minimize the possible side effects. Furthermore, conjugation of immuno-modulatory molecules such as CpG-ODN, cytokines, or toxins which could act specifically to the given allergens, and maleylation of the allergens could maximize the prophylactic or therapeutic effect. Immunotherapies for the pollen allergy and insect sting allergy have been thought to be successful. House dust mite allergy and cockroach allergy have been reported less beneficial by immunotherapeutic approaches. Cockroaches are one of the most important causes of asthma, and severe complications are often reported in the children in city dwellers with low-incomes. The studies of the biological functions of cockroach allergens and the use of recombinant allergens should allow understanding of mechanisms of cockroach-elicited allergic disorders and development of allergen-specific and sensitive diagnostics and tailored therapeutic approaches in the future.

Bla g 6: A Calcium Binding German Cockroach Allergen Involved in Muscle Contraction

RATIONALE: The cockroach allergens that have been identified do not appear to account for the full repertoire of IgE responses. We investigated the importance of other Blattella germanica allergens that could contribute to cockroach allergy.

Use of Recombinant Proteins for Diagnosis of Cockroach Allergy in Patients with Asthma and/or Rhinitis Living in Brazil

Use of Recombinant Proteins for Diagnosis of Cockroach Allergy in Patients with Asthma and/or Rhinitis Living in Brazil

Consultation and referral guidelines citing the evidence: How the allergist-immunologist can help

Consultation and referral guidelines citing the evidence: How the allergist-immunologist can help

Periplaneta americana arginine kinase as a major cockroach allergen among Thai patients with major cockroach allergies.

Periplaneta americana is the predominant cockroach (CR) species and a major source of indoor allergens in Thailand. Nevertheless, data on the nature and molecular characteristics of its allergenic components are rare. We conducted this study to identify and characterize the P. americana allergenic protein. A random heptapeptide phage display library and monoclonal antibody (MAb) specific to a the P. americana component previously shown to be an allergenic molecule were used to identify the MAb-bound mimotope and its phylogenic distribution. Two-dimensional gel electrophoresis, liquid chromatography, mass spectrometry, peptide mass fingerprinting, and BLAST search were used to identify the P. americana protein containing the MAb-specific epitope. We studied the allergenicity of the native protein using sera of CR-allergic Thai patients in immunoassays. The mimotope peptide that bound to the MAb specific to P. americana was LTPCRNK. The peptide has an 83–100% identity with proteins of Anopheles gambiae, notch homolog scalloped wings of Lucilia cuprina, delta protein of Apis mellifera; neu5Ac synthase and tyrosine phosphatase of Drosophila melanogaster, and a putative protein of Drosophila pseudoobscura. This finding implies that the mimotope-containing molecule of P. americana is a pan-insect protein. The MAb-bound protein of P. americana was shown to be arginine kinase that reacted to IgE in the sera of all of the CR-allergic Thai patients by immunoblotting, implying its high allergenicity. In conclusion, our results revealed that P. americana arginine kinase is a pan-insect protein and a major CR allergen for CR-allergic Thai patients.

Predictors of asthma-related health care utilization and quality of life among inner-city patients with asthma

Asthma morbidity and mortality are highest among minority inner-city populations. To identify factors associated with acute health care resource utilization and asthma-related quality of life among high-risk, minority patients with asthma. We interviewed a prospective cohort of 198 adults hospitalized for asthma in an inner city hospital over a period of 1 year. Detailed information about sociodemographics, asthma history, access to care, asthma medications, and self-reported allergy to aeroallergens was collected at baseline. Data on resource utilization (emergency department visits and hospital admissions for asthma) and asthma-related quality of life were obtained at 6 months after discharge. Multivariate analyses were used to identify predictors of resource utilization and quality of life. The mean age of patients was 49.9 +/- 17.4 years, 78% were women, and 97% were nonwhite. At 6 months, 49% of patients had an emergency department visit or hospitalization. In multivariate analysis, adjusting for age, sex, medication regimen, and asthma severity, patients with a physician in charge of their asthma care had lower odds of resource utilization (odds ratio, 0.4; P=.03). Conversely, a self-reported history of cockroach allergy was associated with greater utilization (odds ratio, 2.3; P=.05). Asthma-related quality of life was worse among patients who spoke mostly Spanish or who reported allergy to cockroaches (P < .004). Lack of an established asthma care provider, language barriers, and self-reported allergy to cockroaches are associated with higher resource utilization and worse quality of life among minority, inner-city patients with asthma. Interventions targeting these factors may lead to better outcomes among these patients.

Educational intervention to control cockroach allergen exposure in the homes of hispanic children in Los Angeles: results of the La Casa study

Cockroach allergy is common among inner city children with asthma, and exposure to cockroach allergen is associated with more severe disease. However, there has been little evaluation of educational approaches for controlling cockroach infestations and reducing allergen exposure. An educational intervention to reduce cockroach allergen exposure in the homes of Hispanic children in Los Angeles was implemented and evaluated. Caretakers of 150 children with asthma were randomly assigned to an in-home intervention or comparison group. In the intervention group, peer health educators trained the caretaker to control cockroaches by reducing harbourage and access to food and by applying boric acid, and to reduce allergen exposure by cleaning. Allergen impermeable covers were placed on the child's mattress and pillows. Knowledge, reported and observed behaviour, cockroach counts, and cockroach allergen (Bla g 1) in dust samples from the kitchen and the child's bedding were assessed at study entry and at follow-up 4 months later. There was improvement in knowledge and in observed and reported behaviour hypothesized to be associated with cockroach control. The geometric mean cockroach number in the intervention homes at the follow-up visit was 60% lower than in the non-intervention homes (95% confidence interval (CI) 14%, 81%). Geometric mean total cockroach allergen collected from the child's bedding was 64% lower in the intervention group (95% CI 12%, 85%). In homes with heavier initial cockroach infestation, there was a larger reduction in total kitchen dust allergen and concentration associated with the intervention than in homes with fewer initial cockroaches. We conclude that reduction in number of cockroaches and in total allergen in bedding dust can be achieved by caretakers of asthmatic children following a single home educational intervention by peer educators.

Evaluation of the relationship between cockroach sensitivity and house-dust-mite sensitivity in Turkish asthmatic patients

Exposure to cockroach has been identified as an important source of indoor allergens in patients with asthma and allergic rhinitis. We evaluated the relationship between cockroach sensitivity and other allergens in patients with asthma. A total of 114 patients, defined asthma according to GINA, were enrolled in this study. A questionnaire including age, sex, duration of asthma, history of cockroach presence at home, and total IgE, blood eosinophil count, pulmonary function tests, standard skin prick test additional cockroach and shrimp allergen were performed. There were 84 (73.7%) female and 30 (26.3%) male patients with a mean age of 38.1+10.1 years. The average duration of asthma was 7.7+7.2 years. Sixty five (57%) patients were determined atopic and 49 (43%) nonatopic. Pollen allergen was the most common allergen in 59 (51.8%) patients with asthma, and second common allergen was mite allergen in 43 (37.7%) patients. Cockroach sensitivity were detected in 23 (20.2%) of 114 all asthmatics and 23 (35%) of atopic asthmatics. High rates of house-dust-mite allergy (73.9%) was determined in patients with cockroach sensitivity (P<0.05), while we found no relationship with other allergens. There was no difference for cockroach sensitivity between rural and urban population. Cockroach sensitivity was more common in mild bronchial asthmatics and a female predominance was observed. In addition, there was no association between shrimp and cockroach sensitivity. As a result, a high rate of cockroach sensitivity alone or with mite sensitivity was seen in patients with bronchial asthma in Turkish population. Because of cross-reactivity between mites and cockroach, cockroach sensitivity should be investigated in patients with house-dust-mite allergy. In addition, a high rate of cockroach sensitivity, in terms of IgE sensitization, may be important for the development of new sensitizations.

Allergy immune response is modulated by DNA vaccination for cockroach allergy in mice

Allergy immune response is modulated by DNA vaccination for cockroach allergy in mice

293 Creating a standardized cockroach extract

RATIONALE: To diagnose and treat cockroach allergy, an important factor in inner city asthma, standardized and appropriate potency tests need to be established. We measured allergen levels and overall allergenicity of cockroach extracts, and determined in vivo potency by quantitative serial intradermal testing.

Cloning and expression of trypsin-encoding cDNA from Blattella germanica and its possibility as an allergen

In this study, the trypsin gene (bgtryp-1) from the German cockroach, Blattella germanica, was cloned via the immunoscreening of patients with allergies to cockroaches. Nucleotide sequence analysis predicted an 863 bp open reading frame which encodes for 257 amino acids. The deduced amino acid sequence exhibited 42-57% homology with the serine protease from dust mites, and consisted of a conserved catalytic domain (GDSGGPLV). bgtryp-1 was determined by both Northern and Southern analysis to be a 0.9 kb, single-copy gene. SDS-PAGE and Western blotting analyses of the recombinant protein (Bgtryp-1) over-expressed in Escherichia coli revealed that the molecular mass of the expressed protein was 35 kDa, and the expressed protein was capable of reacting with the sera of cockroach allergy patients. We also discussed the possibility that trypsin excreted by the digestive system of the German cockroach not only functions as an allergen, but also may perform a vital role in the activation of PAR-2.

EVALUATING THE EFFICACY OF ENVIRONMENTAL INTERVENTIONS FOR ALLEVIATING ASTHMA SYMPTOMS AND QUALITY OF LIFE AMONG CHILDREN IN URBAN PUBLIC HOUSING

ISEE-330 Introduction: Asthma severity disproportionately impacts lower-income urban children, in communities where complex environmental, social, and economic exposures exacerbate this multifactorial disease. The Healthy Public Housing Initiative (HPHI), a community-based collaborative of university, government, and community partners, explored whether environmental interventions can be effectively introduced to alleviate asthma symptoms among children in this setting. Methods: Seventy-eight children aged 4 through 17 were recruited from three public housing developments; 58 were retained for longitudinal follow-up of 8 to 20 months. Cockroach and dust mite antigens, mouse urinary protein, and pesticides were sampled before and after interventions (which included intensive cleaning, Integrated Pest Management, mattress replacement, and air cleaners) to estimate pollutant reductions. Outcomes data, collected monthly before and after interventions by trained Community Health Advocates, included Juniper Asthma Quality of Life (AQLQ) questionnaires for both child and caregiver, reports of symptoms, unplanned ED/clinic visits, and changes in medication use. Allergy testing was conducted once, and spirometry was performed at multiple points in time. Information on social exposures associated with immune function (perceived stress, violence, and social support) was collected monthly. Results: Baseline data indicate that only 36% of persistent asthmatics in the intake group used maintenance medications. Allergy testing on a subset of children indicated high prevalence of cockroach (59%) and dust mite (61%) allergies. This prevalent atopy and under-medication suggest strong potential for health improvements with environmental intervention and increased social and medical support. Baseline cross-sectional multivariate regression suggests that time spent around smokers (p=.08) and household size (p=.02) predicts symptoms, which in turn predict child's AQLQ score (p=.0002). Caregiver AQLQ is associated with child's respiratory symptoms (p<.0001), perceived stress (p=.002), and child's having been treated in NICU (p=.09). Longitudinal analyses of AQLQ scores will be presented to evaluate intervention efficacy; the method accounts for seasonality and autocorrelation between repeated measures. Differential response by medical, social, and environmental risk factors related to susceptibility to environmental exposures (including allergy status and perceived stress levels) will be examined. Pre- and post-intervention spirometry scores will be used to corroborate longitudinal results. Discussion: The baseline HPHI results help to identify key factors that influence asthma severity in public housing developments (including time spent around smokers and household size), and to explore the multifactorial nature of the disease by considering many types of exposures (environmental, social, and economic). Longitudinal analysis will allow us to understand whether, and for which children, environmental interventions may reduce asthma severity. We extend our sincere thanks to the West Broadway Task Force, Committee for Boston Public Housing, Boston Housing Authority, Boston Public Health Commission, Tufts University School of Public Health, and many many others who worked long days on the HPHI effort.