Anti-inflammatory and anti-remodeling effects of myrtenol in the lungs of asthmatic rats: Histopathological and biochemical findings

Introduction: Asthma is a chronic inflammatory disease of the airways. In this study, we evaluated the anti-inflammatory effects of myrtenol on the inflammatory indices in the pulmonary parenchyma and airways and on the inflammatory and oxidative indices of the bronchoalveolar lavage fluid (BALF) of asthmatic rats. Methods: The allergic asthma was induced by sensitization (two weeks) followed by the inhalation of ovalbumin (four weeks). Animals were divided into two main groups: (1) Histopathology, and (2) measurement of inflammatory and oxidative biomarkers in the BALF. Each main group was subdivided into four subgroups: Control, Asthma, Asthma + Dexamethasone and Asthma + Myrtenol. (-)-Myrtenot (50 mg/kg) or Dexamethasone (2.5 mg/kg) was administered intraperitoneally once a day for one week, at the end of the inhalation period. On day 50, lung histopathologic parameters and inflammatory indices in BALF including INF-gamma, IL-10, IL-1 beta, and TNF-alpha and oxidative stress biomarkers (MDA, SOD, and GPX) were measured. Result: In the Asthma group, leukocyte infiltration, the thickness of smooth muscle and epithelium of airways wall and the number of goblet cells increased. Myrtenol reduced all of the above-mentioned indices except the epithelium thickness. It also inhibited the increase in BALF IL-1 beta, TNF-alpha and MDA and increased the levels of INF-gamma, IL-10 and SOD. Conclusion: Our results suggest that myrtenol reduced damage caused by experimental asthma by reducing the inflammatory indices, normalizing the level of interleukins and balancing oxidative stress in the lungs. It also prevented airway remodeling. Myrtenol may be suggested as a potent herbal medicine for the treatment of allergic asthma. (C) 2018 SEICAP. Published by Elsevier Espana, S.L.U. All rights reserved.