Treatment with a Fel d 1 hypoallergen reduces allergic responses in a mouse model for cat allergy.

BACKGROUND: A hypoallergen of the major cat allergen Fel d 1, recombinant (r) Fel d 1 (DTE III), was previously shown to have retained T-cell reactivity and strongly reduced IgE-binding capacity compared to unmodified rFel d 1. Here, we evaluated the therapeutic capacity of rFel d 1 (DTE III) in a mouse model for cat allergy. METHODS: Mice were subcutaneously (s.c.) sensitized with rFel d 1 and subsequently treated (s.c.) with 50 or 200 µg rFel d 1 (DTE III), or 50 µg rFel d 1, prior to intranasal challenge with cat dander extract. Airway hyperreactivity (AHR), cells and cytokines in bronchoalveolar lavage fluid, splenocyte in vitro response, and serum immunoglobulins were analyzed. Seven cat-allergic patients and ten healthy controls were tested for skin prick test (SPT) reactivity to rFel d 1 (DTE III) and rFel d 1. RESULTS: Mice treated with 50 and 200 µg rFel d 1 (DTE III), and 50 µg rFel d 1, produced increased serum levels of rFel d 1-specific IgG1 and IgG2a compared to sham-treated mice. IgG from all treatment groups could block binding of patients' IgE to rFel d 1. The 200 µg rFel d 1 (DTE III) treatment tended to reduce AHR. All mice tolerated treatment with rFel d 1 (DTE III), in contrast to only four of ten treated with rFel d 1. Compared to rFel d 1, the hypoallergen showed a tendency of reduced SPT reactivity. CONCLUSION: The rFel d 1 (DTE III) hypoallergen might be a promising candidate for application in immunotherapy of cat allergy with improved safety and efficacy.

Dissociation of airway inflammation and hyperresponsiveness by cyclooxygenase inhibition in allergen challenged mice.

The aim of the current study was to define how cyclooxygenase (COX)-activity affects airway hyperresponsiveness (AHR) and inflammation using interventions with COX inhibitors at different time points during allergen challenge and/or prior to measurement of AHR in an eosinophil-driven allergic mouse model. Inflammatory cells were assessed in bronchioalveolar lavage (BAL) and AHR was evaluated as the total lung resistance to methacholine (MCh) challenge. Administration of FR122047 (COX-1 inhibitor) during ovalbumin (OVA) challenge and prior to MCh challenge enhanced AHR without affecting the inflammatory cell response. In contrast, administration of lumiracoxib (COX-2 inhibitor) during the same time period had no effect on AHR but reduced the inflammatory cells in BAL. Nonselective COX inhibition with diclofenac both enhanced the AHR and reduced the inflammatory cells. Administration of diclofenac only during OVA challenge reduced the cells in BAL without any changes in AHR, whereas administration of diclofenac only prior to MCh challenge enhanced AHR but did not affect the cells in BAL. The present study implicates distinct roles of prostanoids generated along the COX-1 and COX-2 pathways and, furthermore, that inflammatory cells in BAL do not change in parallel with AHR. These findings support the fact that AHR and the inflammatory response are distinct and, at least in part, uncoupled events.

Prolonged antigen-exposure with carbohydrate particle based vaccination prevents allergic immune responses in sensitized mice.

BACKGROUND: Defined particles carrying tightly bound allergens at high density have been suggested as alternatives in allergy vaccination. Carbohydrate based particles (CBP), sized 2 microm, provide a platform for covalent coupling of allergens. OBJECTIVE: To investigate the mechanisms of antigen presentation by CBP, as well as cellular and humoral responses after vaccination with the major cat allergen Fel d 1, covalently coupled to CBP. METHODS: Mice (n = 10/group) were subcutaneously vaccinated with CBP-rFel d 1, CBP or phosphate buffer saline (PBS) before sensitization with rFel d 1 and challenged with cat dander extract. Fluorescent and (75)Se-radiolabeled tracking of allergens and particles were performed with flow cytometry and whole-body autoradiography. Humoral, cellular and regulatory immune responses were analyzed by ELISA and flow cytometry. Cytokines were measured in bronchoalveolar lavage fluid and splenocyte cultures. RESULTS: CBP-rFel d 1 prevented induction of airway inflammation and induced allergen-specific T-cell anergy. CBP-rFel d 1 also induced rapid IgM and IgG1-responses compared with soluble rFel d 1. Particles were phagocytosed by antigen-presenting cells and transported to draining lymph nodes and spleen. Moreover, antigen coupled to CBP remained longer at the injection site compared with alum. CONCLUSIONS: Covalent coupling of rFel d 1 to CBP induces rapid antibody production, prevents induction of allergic immune responses and systemic allergen spreading. Thus, CBP comprise several attractive adjuvant features for use in allergy vaccination. CLINICAL IMPLICATIONS: Prolonged allergen exposure through covalent coupling to particles suitable for phagocytosis, provides an adjuvant for safer and efficient allergy vaccination.

Carbohydrate-based particles reduce allergic inflammation in a mouse model for cat allergy.

BACKGROUND: Allergen-specific immunotherapy (ASIT) is the only treatment of allergic disease that gives long-lasting relief of symptoms. However, concerns for safety and efficiency have highlighted the need for improvement of the therapy. We have previously suggested carbohydrate-based particles (CBPs) as a novel adjuvant and allergen carrier for ASIT. Our aim of this study was to evaluate the therapeutic potential of CBPs in ASIT, employing a mouse model for cat allergy. METHODS: BALB/c mice were subcutaneously immunized with the recombinant (r) cat allergen Fel d 1 followed by intranasal challenge with cat dander extract (CDE). The sensitized mice were therapeutically treated with rFel d 1 covalently coupled to CBPs (CBP-rFel d 1). Airway hyper-reactivity (AHR), infiltration of leucocytes in bronchoalveolar lavage (BAL) fluid, allergen-specific serum immunoglobulin levels and in vitro splenocyte responses were evaluated. RESULTS: Mice treated with CBP-rFel d 1 showed reduced features of allergic inflammation. They responded with (i) significantly decreased AHR and infiltration of eosinophils in BAL fluid after CDE challenge, (ii) the serum level of rFel d 1-specific IgE was reduced and the level of IgG(2)a was more pronounced after CBP-rFel d 1 treatment, and (iii) there was also a tendency of decreased allergen-specific cellular response. CONCLUSIONS: Carbohydrate-based particles are effective tools as adjuvant and allergen carriers for use in ASIT and constitutes a promising strategy to improve allergy treatment.