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| Author(s): |
Flavia Castro Ribas de Souza
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: | 2012-03-09 |
| Examining board members: |
Iolanda de Fátima Lopes Calvo Tibério;
Fernanda Magalhães Arantes Costa;
Carla Máximo Prado
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| Advisor: | Iolanda de Fátima Lopes Calvo Tibério |
| Abstract | |
Introduction: It is estimated that 10% of asthma patients have symptoms and important limitations such as frequent exacerbations or persistent reduction of resiratory function, despite the use of corticosteroids. The alterations of distal lung parenchyma have been recently evaluated on asthma pathophysiology, particulary in patients with refractory asthma and difficcult to control. These patients have increased oxidative stress responses, mainly with significant activation of iNOS. Aims: We evaluated the effects of montelukast or dexamethasone treatments associated or not to an iNOS inhibitor (1400W) on eosinophilic response, extracellular matrix remodeling, oxidative stress, actin content, IL4, IL5, MMP9, TIMP1, IFN gama, TGF beta positive cells of distal lung parenchyma in guinea pigs with chronic alergic inflammation. Methods: Guinea Pigs were inhaled with ovalbumin (OVA group) twice a week for four weeks. After 4th inhalation, GP were treated with montelukast (OVAM group-10mg/Kg/PO/day) or dexamethasone (OVAD group-5mg/Kg/IP/day). The treatment with iNOS inhibitor 1400W (OVAW group-1mg/kg/day) was given daily in the last 4 days (OVAW, OVADW and OVAMW groups). After 72 hours of 7th inhalation, GP were anesthetized, lung strips were retired and submitted to histopathological evaluation. Results: There was an increase in eosinophilic infiltrate, in the number of positive cells for IL4, IL5, TIMP1, MMP9, iNOS, IFN gama TGF beta, actin, isoprostane PGF2 alpha, elastic and collagen fiber contents in OVA animals comparing to SAL group (p<0,05). There was a decrease in the number of eosinophils, IL4, IL5, MMP9, TIMP1, IFN gama, TGF beta positive cells, collagen, actin and isoprostane PGF2 alpha content in all treated groups compared to OVA animals (p<0.05), but the treatment with montelukast did not reduce the positive cells for IFN gama, compared to OVA (p>0.05). Elastic fiber content were reduced only in OVAMW, OVADW and OVAW groups compared to OVA animals (p<0.05). The association of 1400W and montelukast treatments potentiated the reduction of actin, elastic fibres and isoprostane PGF2 alpha contents and the number of IL4, IL5, TIMP1, IFN gama, TGF beta and iNOS positive cells compared to montelukast group (p<0.05). The treatments with 1400W and dexamethasone contributed to a greater reduction of elastic fibers, actin and isoprostane PGF2 alpha contents and the number of IL4, IL5, IFNgama and TIMP1 positive cells compared to dexamethasone group (p<0.05). Conclusions: Corticosteroid treatment associated to iNOS inhibition contributes to a greater reduction of extracellular matrix remodeling, decreases the oxidative stress, and also is efficient to attenuate the Th2 inflammatory response in distal lung parenchyma. On the other hand, montelukast treatment associated to iNOS inhibition showed a higher efficacy to reduce elastic fibres content, oxidative stress activation, actin content and IL4 and IL5 expression in distal lung parenchyma. These associations may represent future pharmacological tools for controlling distal pulmonary histopathological alterations induced by chronic inflammation (AU) | |