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| Author(s): |
Rafael de Almeida dos Reis
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD) |
| Defense date: | 2008-09-11 |
| Examining board members: |
Iolanda de Fátima Lopes Calvo Tibério;
José Antonio Atta;
Adenir Perini
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| Advisor: | Iolanda de Fátima Lopes Calvo Tibério |
| Abstract | |
Background: It has increasing evidence linking the role of stress in the onset of asthma exacerbation and in the maintenance of asthmatic crises, as well as the importance of mucus production and the mucociliary clearance in the asthma physiopathology. Objectives: So, we consider relevant to evaluate in guinea pigs with pulmonary chronic allergic inflammation how the induced repeated physical stress, caused by forced swimming, modulates the mucociliary clearance, the mucus properties, the eosinophilic infiltration and the IL-13 expression on bronchial epithelial cells in the airway wall. Methods: The animals had received inhalations two times per week during four weeks with increasing doses of ovalbumin (OVA and OVA-S groups) or saline solution (SAL and SAL-S groups). After twenty four hours of the 4th inhalation, the animals (named as SAL-S and OVA-S groups) had been submitted to the protocol of forced swimming, per ten days with an interval of two days, for the stress induction. After 72 hours of the last inhalation, the animals were anaesthetized and the tracheal mucus clearance (TMC), the ciliary beat frequency (CBF), and the difference of transepithelial potential difference (PD) were measured. After these measurements had been done mucus samples were collected for evaluation of the contact angle (CA) and cough transportability (CT). To serum cortisol dosage a little amount of blood was collected. The lungs were dissected, fixed and submitted to histological techniques, like LUNA stain for identification of eosinophils and the IL-13 immunohistochemistry technique for its detection in the bronchial epithelium and in the inflammatory cells present in the airways walls. The adrenal glands were excised, immediately weighed and submitted to haematoxylin and eosin stain for histopathological evaluation using the morphometry to determine the areas of each of their layers. Results: The animals of OVA Summary group presented a reduction of the TMC, the PD, and the CT. On the other hand they presented an increase of the CA, of the airways epithelial area, of the acid mucus, of the eosinophils number as well as on the IL-13 expression in the airways epithelium and on the inflammatory cells around the airways, compared to the controls (p<0.05 for all comparisons). There was a reduction of the adrenal gland total area and on each one of its layers compared to the controls (p<0.05 for all comparisons). The animals submitted to the forced swim stress protocol (SAL-S and OVA-S groups) showed an increase on serum cortisol levels, on adrenal gland weight compared to OVA group (p<0.05). The animals submitted to the forced swim stress protocol and to the sensitization protocol with ovalbumin (OVA-S) showed a reduction in the TMC and an increase on the CA, bronchial epithelial acid mucus area and in all adrenal gland layers compared to the results obtained in the OVA group animals (p<0.05 for all comparisons). Conclusions: The chronic inflammatory pulmonary process alters the mucociliary transport and mucus rheological properties which was associated to eosinophilic recruitment, increases in the IL-13 expression on bronchial epithelial cells and inflammatory cells in airway walls. In addition, we observed a reduction in all adrenal zones. In this experimental model the repeated physical stress reduces the mucociliary clearance due to the mucus rheological properties alterations, particularly increasing the amount of acid mucus and its wettability and adhesivity. These effects seem to be related to the adrenal activation but independently of the eosinophilic recruitment and of Th2 responses mediated by IL-13 (AU) | |