Biomedical subjects

Judith A Woodfolk

Publications and source records attributed to Judith A Woodfolk.

14 recordsLinked to original sources

PubMed2006

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

BACKGROUND: The known cockroach allergens do not appear to account for the full repertoire of IgE responses. OBJECTIVE: To identify and investigate the importance of other Blattella germanica allergens contributing to cockroach allergy. METHODS: 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. RESULTS: 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. CONCLUSION: Bla g 6 is a troponin allergen with a calcium dependent IgE reactivity that may be involved in muscle contraction. CLINICAL IMPLICATIONS: Bla g 6 homologous allergens may occur among other insects and cause cosensitization or allergenic cross-reactivity.

Allergens↗

PubMed2006

Selective roles and dysregulation of interleukin-10 in allergic disease.

There is mounting evidence to support a role for interleukin (IL)-10 in the regulation of both allergic and nonallergic immune responses. The current view is that IL-10 influences Th2-driven allergic processes by altering the interplay between Th1 and Th2 effector cells. However, lack of a clear delineation of the different types of IL-10-secreting regulatory T cells poses a major challenge in defining IL-10-mediated immune pathways, which govern the development, persistence, and modulation of allergic status. This is compounded by observations that undermine the credibility of the Th1/Th2 paradigm as a model for allergic disease. Nevertheless, enhanced IL-10 secretion by T cells during conventional immunotherapy, coupled with evidence of a link between genetics and high IL-10 production to a specific allergen, suggests that IL-10 induction is an appropriate goal of therapy. Knowledge of the targeted patient population and design of an immunogen (ie, peptide or modified allergen) within this context are likely to provide improved results over conventional immunotherapy.

Allergens↗

PubMed2006

Environmental factors influencing allergy and asthma.

Despite the strong and consistent association between immediate hypersensitivity, allergy, asthma and exposure, there is still controversy about the role inhaled allergen plays and about the timing of events related to sensitization. However, IgE antibodies are essential for the asthmatic response and the symptoms are much more closely associated with IgE antibodies to perennial than to seasonal allergens. Although there have been many changes in our environment, none of these alone explains the consistency or the scale of the rise in asthma over the 40 years between 1960 and 2000.

Animals↗

PubMed2005

A new paradigm for immunoglobulin E in allergic diseases.

Recent observations at the level of the antigen presenting cell, as well as the T cell, point toward a pivotal role for interleukin (IL)-10 in the control of immunoglobulin E (IgE)-mediated allergic diseases, such as asthma and rhinitis. This has led to restructuring of the Th1/Th2 paradigm with IL-10 acting to modulate Th2-driven IgE antibody (Ab) responses. The modified Th2 response to cat allergen is associated with high-dose allergen exposure and the presence of high titer IgG and IgG4 Ab; however, IgE Ab and allergic symptoms are absent. Characteristics of this immune response indicate that it is a variant of the allergic response, which develops in an IL-10-dependent manner, but it is distinct from other types of nonallergic or tolerant responses. These observations point toward a new paradigm for the development of IgE-mediated responses. This may be important for advancing our understanding of the response to immunotherapy and anti-IgE, and for defining immune mechanisms that drive allergic responses.

Animals↗

PubMed2005

Quantitative measurement of IgE antibodies to purified allergens using streptavidin linked to a high-capacity solid phase.

BACKGROUND: Commercially available assays for IgE antibody provide results in international units per milliliter for many allergen extracts, but this is not easily achieved with purified or novel allergens. OBJECTIVE: To develop assays for IgE antibody suitable for purified or novel allergens by using a commercially available immunosorbent. METHODS: Streptavidin coupled to a high-capacity immunosorbent (CAP) was used to bind biotinylated purified allergens from mite (Der p 1 and Der p 2), cat (Fel d 1), and dog (Can f 1). Assays for IgE antibody to these allergens were performed on sera from children (asthma and control) as well as adults with atopic dermatitis. RESULTS: The results were validated by serial dilution of sera with high and low levels of IgE antibody and were quantitated in international units per milliliter by using a standard curve. Values for IgE antibody to Der p 1, Der p 2, and Fel d 1 correlated with values obtained with the allergen extracts (r2 = 0.80, 0.84, and 0.95, respectively; P < .001 in each case). Furthermore, the values for IgE antibody in sera from children with high exposure to mite and cat allergens demonstrated 10-fold higher levels of IgE antibody to Der p 1 and Der p 2 than to Fel d 1 (P < .001). CONCLUSION: The streptavidin immunosorbent technique provides a new method for quantifying IgE antibody to purified proteins. The results provide evidence about the high quantities of IgE antibody to purified inhalant allergens in patients with atopic dermatitis. In addition, the results demonstrate major differences in IgE antibodies specific for mite and cat allergens among children with high exposure to both allergens.

Adult↗

PubMed2005

Specific IgE and IgG antibody-binding patterns to recombinant cockroach allergens.

BACKGROUND: The specificity of serum antibody responses to different cockroach allergens has not been studied. OBJECTIVE: We sought to quantitate serum IgE and IgG antibodies to a panel of purified cockroach allergens among cockroach-sensitized subjects. METHODS: IgE antibodies to recombinant cockroach allergens (rBla g 1, rBla g 2, rBla g 4, rBla g 5, and rPer a 7) were measured in sera containing IgE antibodies to Blattella germanica extract (n = 118) by using a streptavidin CAP assay and a multiplex flow cytometric assay. Specific IgG antibodies were determined by using radioimmunoprecipitation techniques. RESULTS: Specific IgE antibodies measured by means of CAP assay and multiplex assay were strongly correlated ( r = 0.8, P < .001). The sum of IgE antibodies (in international units per milliliter) against all 5 allergens equated to IgE antibodies to cockroach extract. Although the prevalence of IgE antibodies was highest for rBla g 2 (54.4%) and rBla g 5 (37.4%), patterns of IgE antibody binding were unique to each subject. Surprisingly, only 16% of cockroach-sensitized subjects with IgE antibodies to house dust mite exhibited IgE antibody binding to cockroach tropomyosin (rPer a 7). Specific IgE antibodies were associated with increased IgG antibody levels, although detection of IgG in the absence of IgE was not uncommon. CONCLUSION: The techniques described offer a new approach for defining the hierarchy of purified allergens. IgE antibodies directed against 5 allergens constitute the majority of the IgE antibody repertoire for cockroach. Such distinct patterns of IgE-IgG responsiveness to different cockroach allergens highlight the complexity of B-cell responses to environmental allergens.

Adolescent↗

PubMed2005

Airborne endotoxin in homes with domestic animals: implications for cat-specific tolerance.

BACKGROUND: Although endotoxin is known to increase symptoms in allergic individuals, early exposure might decrease sensitization. Similarly, the presence of an animal in the home has been associated with decreased sensitization to animal allergens. It has been suggested that the effect of animals could be explained by increased endotoxin exposure. OBJECTIVE: We sought to investigate the effects of domestic animals on airborne endotoxin. METHODS: By using a silent particle collector, air was sampled over 24 hours in homes with or without animals. The total volume sampled was approximately 1000 m3, which provides quantities of allergen and endotoxin that can easily be measured with standard assays. RESULTS: The quantity of endotoxin ranged from less than 0.5 to more than 500 pg/m3, whereas cat and dog allergen ranged from less than 0.002 to more than 5 ng/m3. Overall, the quantity of airborne endotoxin was not higher in homes with at least one animal. However, airborne endotoxin levels were significantly lower in homes with a cat compared with homes with a dog (P < .001). In keeping with this, there was a significant correlation between airborne Can f 1 and airborne endotoxin (r = 0.50, P < .01) but not between endotoxin and Fel d 1 (r = 0.17, P = .27). CONCLUSIONS: The results demonstrate that endotoxin is present in the air of almost all homes. Although higher levels were seen in homes with a dog, similar levels might be present in homes with no animals. The results argue that the effects of cat ownership cannot be explained by increased exposure to endotoxin.

Air Pollutants↗

PubMed2005

Allergy and dermatophytes.

Tinea pedis (athlete's foot) and onychomycosis (infection of the toenails) caused by the dermatophyte fungus Trichophyton are highly prevalent in adults. Several Trichophyton allergens have been identified based on elicitation of immunoglobulin E antibody-mediated immediate-hypersensitivity (IH) responses. Evidence of an etiologic role for Trichophyton in asthma in some subjects with IH and chronic dermatophytosis is provided by bronchial reactivity to Trichophyton. Improvement of asthma after systemic antifungal treatment corroborates this link. A unique feature of Trichophyton allergens is the ability of the same antigen to elicit delayed-type hypersensitivity (DTH) in individuals who lack IH reactivity. Delayed responses appear to confer protection, while IH responses do not, based on the association with acute versus chronic skin infection. The amino acid sequence identity of Trichophyton allergens with diverse enzyme families supports a dual role for these proteins in fungal pathogenesis and allergic disease. Characterizing the immunologic properties of Trichophyton allergens and defining immune mechanisms which drive dichotomous responses are pivotal to understanding the dermatophyte-allergy relationship. Recent studies have identified DTH-associated major T-cell epitopes which could facilitate the development of peptide vaccines. Characterization of additional molecular targets by using new techniques may aid not only in the eradication of infection but also in the resolution of allergic symptoms.

Adult↗

PubMed2005

Markers for host-induced gene expression in Trichophyton dermatophytosis.

Dermatophytes are adapted to infect keratinized tissues by their ability to utilize keratin as a nutrient source. Although there have been numerous reports that dermatophytes like Trichophyton sp. secrete proteolytic enzymes, virtually nothing is known about the patterns of gene expression in the host or even when the organisms are cultured on protein substrates in the absence of a host. We characterized the expression of an aminopeptidase gene, the Trichophyton mentagrophytes homolog of the Trichophyton rubrum Tri r 4 gene. The T. rubrum gene was originally isolated based on the ability of the protein encoded by it to induce immediate and delayed-type hypersensitivity in skin tests. T. mentagrophytes Tri m 4 is closely related to Tri r 4 (almost 94% identity at the protein level). Tri m 4 resembles other protease-encoding genes thought to be virulence factors (for example, DPP V of Aspergillus fumigatus). The Tri m 4 protein was detected immunochemically both in fungal extracts and in the culture medium. Expression of the Tri m 4 gene was induced severalfold when T. mentagrophytes was grown on keratin and elastin. Ex vivo, strong induction was observed after culture on blood plasma, but the use of homogenized skin did not result in a significant increase in Tri m 4 transcript levels. In order to identify additional genes encoding putative virulence factors, differential cDNA screening was performed. By this method, a fungal thioredoxin and a cellulase homolog were identified, and both genes were found to be strongly induced by skin extracellular matrix proteins. Induction by superficial (keratin) and deep (elastin) skin elements suggests that the products of these genes may be important in both superficial and deep dermatophytosis, and models for their function are proposed. Upregulation of several newly identified T. mentagrophytes genes on protein substrates suggests that these genes encode proteins which are relevant to the dermatophyte-skin interaction.

Amino Acid Sequence↗

PubMed2005

High-dose allergen exposure leads to tolerance.

Reports of decreased sensitization to cat allergen (Fel d 1) among individuals living with a cat or subjects exposed to high-dose cat allergen may be explained by the development of a form of high-dose tolerance resulting from natural exposure to an inhalant allergen. Although the epidemiological data regarding the relationship between exposure and sensitization to Fel d 1 are conflicting, the ability for high-dose Fel d 1 to induce a characteristic nonallergic immune response with a distinctive serum antibody profile has been established. Definition of this modified T-helper (Th)2 response to cat allergen, coupled with the renewed interest in regulatory T cells within the immunology field, has provided an avenue for exploring the mechanism by which IgE antibody-mediated responses are controlled. There is mounting evidence to suggest that the modified Th2 response is a variation of the allergic response and that the modified Th2-allergic axis is influenced by allergen dose and genetics. This article discusses putative immune mechanisms of tolerance within the context of an allergen-specific system. The relevance of high-dose allergen exposure and alternate factors such as endotoxin to the development of tolerance is considered. Fel d 1 exhibits unique molecular and immunological characteristics that may contribute to its tolerogenic properties. Major T-cell epitopes of Fel d 1 that preferentially induce regulatory factors have been defined. Furthermore, high-titer IgE antibody responses associated with atopic dermatitis are characterized by a defect in the T-cell repertoire that is specific to these epitopes. Identification of Fel d 1 epitopes that induce interleukin-10 may provide new targets for treatment.

Allergens↗

PubMed2004

A role for IL-10-mediated HLA-DR7-restricted T cell-dependent events in development of the modified Th2 response to cat allergen.

Although high dose exposure to inhaled cat allergen (Fel d 1) can cause a form of tolerance (modified Th2 response), the T cell mechanism for this phenomenon has not been studied. T cell responses to Fel d 1 were characterized in both allergic (IgE(pos)) and modified Th2 (IgE(neg)IgG(pos)) responders as well as serum Ab-negative controls (IgE(neg)IgG(neg)). Fel d 1 stimulated high levels of IL-10 in PBMC cultures from all individuals, with evidence of Th2 and Th1 cytokine skewing in allergic and control subjects, respectively. Using overlapping peptides, epitopes at the N terminus of Fel d 1 chain 2 were shown to stimulate strong T cell proliferation and to preferentially induce IL-10 (peptide 2:1 (P2:1)) or IFN-gamma (P2:2) regardless of the allergic status of the donor. Injection of cat extract during conventional immunotherapy stimulated expansion of IL-10- and IFN-gamma-producing chain 2 epitope-specific T cells along with increased Fel d 1-specific serum IgG and IgG4 Ab. Six of 12 modified responders expressed the major HLA-DRB1 allele, *0701, and both P2:1 and P2:2 were predicted ligands for this allele. Cultures from DR7-positive modified responders produced the highest levels of IL-10 to P2:1 in addition to other major and minor epitopes within chains 1 and 2. In the presence of anti-IL-10 mAb, both T cell proliferation and IFN-gamma production were enhanced in a Fel d 1- and epitope-specific manner. We conclude that IL-10-producing T cells specific for chain 2 epitopes are relevant to tolerance induction, and that DR7-restricted recognition of these epitopes favors a modified Th2 response.

Adult↗

PubMed2003

Mechanisms of tolerance to inhalant allergens: the relevance of a modified Th2 response to allergens from domestic animals.

Subjects can be "non-allergic" because (1) they are not exposed, (2) they fail to make an immune response, or (3) they make an immune response that does not include IgE antibodies (Ab). The recent observation that children raised in a house with a cat are less likely to become allergic to cat allergen than those who only get indirect exposure provides a model to investigate the factors controlling allergic responses. Many of these highly exposed children have made an IgG and IgG4 Ab response to Fel d 1 without IgE Ab, i.e., a "modified Th2 response". In countries where cats are a major cause of asthma, the presence of a cat may decrease the risk of asthma. By contrast, in countries with high exposure to dust mites, cats can induce specific tolerance to Fel d 1 without influencing asthma or the IgE Ab response to dust mites. Using overlapping peptides to investigate T cell responses to Fel d 1 suggests that the structure of the molecule plays a special role in inducing the T cell responses that can "control" the immune response to cat allergens. This T cell response is characterized by high levels of IL-10 production, but this is not restricted to those who have made a modified Th2 response. The results suggest that there are major differences in the immune response to different allergens that profoundly affect their role in allergic disease. Dust mite and cockroach differ from cat (and rat) allergens not only in the quantity inhaled and the particles' sizes but also in the biochemistry of the molecule.

Allergens↗

PubMed2003

Animal danders.

Animals release proteins into their surroundings through secretions, as excretions, or as dander. The quantity of dander that is dispersed by cats, dogs, or humans is sufficient to supply food for dust mites and to supply easily measurable quantities of proteins in dust. Fel d 1, Can f 1, and human IgA or IgG can be found in microgram quantities in dust samples. Allergens also can accumulate from the urine of wild or pet rodents. For cats and dogs, the accumulation of dander particles is not related to the cleanliness of the animals. All animals, including humans, provide a fully adequate supply of organic material for bacterial growth in a carpet, provided conditions are sufficiently humid. The authors' preliminary results in Virginia do not find a significant difference in endotoxin between homes with or without animals. The likely explanation for the nonallergic IgG and IgG4 response to cat, dog, or rat allergens is high exposure to proteins from these animals. If the highest levels of cat allergen in a home can result in immunologic tolerance, it is unlikely that primary avoidance would be successful at reducing exposure. The data showing that 80% of Swedish children with cat allergies never had lived with a cat imply that the concentrations of cat allergen in schools or in houses without a cat are sufficient to cause sensitization. Primary prevention would be possible only on a community basis, which is unlikely to occur. Sensitization to cat, rat, dog, or mouse allergens consistently is associated with asthma. In symptomatic children with positive skin test results, there is a strong case for allergen avoidance and a clear need for controlled trials. Controlled trials of avoidance should include houses without cats and schools. Controlling exposure to cat allergens with the cat in situ requires aggressive measures, such as removing reservoirs, washing the cat, and air cleaning. Many allergic or symptomatic children who live with a cat do not have positive skin test results or positive IgE antibodies to cats. Avoidance measures related to animals should be recommended only for individuals with positive skin test results. Increasing evidence shows that exposure to cats, dogs, rats, and other animals can induce a form of immunologic tolerance without causing allergic disease, and it is important to understand why this change occurs with dander allergens rather than with all allergens. The most probable explanations are related to the form and quantity of airborne allergens.

Air Pollution, Indoor↗

PubMed2002

The immune response to intrinsic and extrinsic allergens: determinants of allergic disease.

A central role for Th2 effector cells in IgE-mediated allergic disease is well established. However, the question of why some individuals develop allergic disease and others do not remains largely unanswered. Until recently, the prevailing view was that the allergic response reflected a shift in the Th1/Th2 'balance' to favor production of Th2 cytokines and IgE antibody isotype switching. Evidence is now emerging to suggest that distinct allergic responses cannot be distinguished simply on the basis of type 1 and type 2 cytokine profiles. For example, delayed-type hypersensitivity responses to intrinsic allergens derived from the dermatophyte fungus Trichophyton are associated with a paradoxical increase in Th2 cytokines compared with immediate hypersensitivity responses. In contrast, analysis of 'tolerant' responses to extrinsic allergens which are induced by specific immunotherapy or high-dose natural exposure to inhaled allergen (the modified Th2 response) supports a role for both the Th1 cytokine IFN-gamma and the regulatory cytokine IL-10. However, IL-10 may also be a critical mediator in the allergic response. In this article, we examine how analysis of epitope-specific T cell responses may lead to an understanding of how T lymphocyte cytokines relate to distinct allergic phenotypes. The relevance of Th1/Th2 and regulatory cytokines to development of new allergen-specific therapies is also discussed.

Allergens↗