Sensitization by subcutaneous route is superior to intraperitoneal route in induction of asthma by house dust mite in a murine mode

Abstract

Objective: To develop a new experimental model of chronic allergic pulmonary disease induced by house dust mite, with marked production of specific immunoglobulin E (IgE), eosinophilic inflammatory infiltrate in the airways and remodeling, comparing two different routes of sensitization.

Methods: The protocol lasted 30 days. BALB/c mice were divided into six groups and were sensitized subcutaneously or intraperitoneally with saline (negative control), Dermatophagoides pteronyssinus (Der p) 50 or 500 mcg in three injections. Subsequently they underwent intranasal challenge with Der p or saline for 7 days and were sacrificed 24 hours after the last challenge. We evaluated the titration of specific IgE anti-Der p, eosinophilic density in peribronchovascular space and airway remodeling.

Results: Both animals sensitized intraperitoneally and subcutaneously produced specific IgE anti-Der p. Peribronchovascular eosinophilia increased only in mice receiving lower doses of Der p. However, only the group sensitized with Der p 50 mcg through subcutaneously route showed significant airway remodeling.

Conclusion: In this murine model of asthma, both pathways of sensitization led to the production of specific IgE and eosinophilia in the airways. However, only the subcutaneously route was able to induce remodeling. Furthermore, lower doses of Der p used in sensitization were better than higher ones, suggesting immune tolerance. Further studies are required to evaluate the efficacy of this model in the development of bronchial hyperresponsiveness, but it can already be replicated in experiments to create new therapeutic drugs or immunotherapeutic strategies.

Conflict of interest statement

Conflict of interest: none.

Figures

Figure 1. Diagram of the protocol for sensitization, challenge, and sacrifice with duration of 30 days (D0 to D29)

Figure 2. Values of mean ± standard error of the titration of specific IgE anti-Dermatophagoides pteronyssinus by the passive cutaneous anaphylaxis technique

Figure 3. Values of mean ± standard error of the titration of specific IgG1 anti-Dermatophagoides pteronyssinus by the immunoenzymatic assay technique (ELISA)

Figure 4. Values of mean ± standard error of the eosinophilic density in the peribronchovascular space (hematoxylin-eosin). The density was determined by the count of number of eosinophils present in the inflammatory infiltrate, between the bronchus and the adjacent artery, divided by the number of points corresponding to the total area of the inflammatory infiltrate, with a 1000x magnification

Figure 5. Evaluation of airway remodeling by the quantification of collagen fibers stained by Picrosirius. The collagen area (mean ± standard error) was expressed by a ratio of the area of the collagen fibers (in µm2) and the perimeter of the airway (in µm2)

Figura 1. Esquema do protocolo de sensibilização, provocação e sacrifício com duração de 30 dias (D0 a D29)

Figura 2. Valores de média ± erro padrão da titulação da IgE específica anti-Dermatophagoides pteronyssinus pela técnica da passive cutaneous anaphylaxis

Figura 3. Valores de média ± erro padrão da titulação da IgG1 específica anti- Dermatophagoides pteronyssinus pela técnica da ensaio imunoenzimático (ELISA)

Figura 4. Valores de média ± erro padrão da densidade eosinofílica no espaço peribroncovascular (hematoxilina e eosina). A densidade foi determinada pela contagem do número de eosinófilos presentes no infiltrado inflamatório, entre o brônquio e a artéria adjacente, dividido pelo número de pontos correspondendo à área total do infiltrado inflamatório, num aumento de 1000x

Figura 5. Avaliação do remodelamento das vias aéreas pela quantificação de fibras colágenas coradas por Picrosirius. A área do colágeno (média ± erro padrão) foi expressa em uma relação entre a área das fibras colágenas (em µm2) e o perímetro da via aérea (em µm2)