Abstract
Airway remodeling in asthma contributes to airway hyperreactivity, loss of lung function and persistent symptoms. Current therapies do not adequately treat the structural airway changes associated with asthma. Statin drugs have improved respiratory health and their therapeutic potential in asthma has been tested in clinical trials. However, the mechanism of action of statins in this context has remained elusive. The present study hypothesized that atorvastatin treatment of ovalbumin-exposed mice attenuates early features of airway remodeling via a mevalonate-dependent mechanism. BALB/c mice were sensitized with ovalbumin and atorvastatin was delivered via oral gavage prior to each ovalbumin exposure. Reverse transcription-semi-quantitative polymerase chain reaction (RT-semi-qPCR), ELISA and western blot analysis were used to assess the expression of a number of relevant genes, including tissue transglutaminase (tTG), triggering receptor expressed on myeloid cells (TREM)-1, nuclear factor erythroid 2-related factor (Nrf) 2, hypoxia-inducible factor (HIF)-1α, transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-9 and tissue inhibitors of metalloproteinases (TIMP)-1 in lung tissue. α-Smooth muscle actin (α-SMA) activity was measured by immunohistochemistry. Airway hyperresponsiveness, lung collagen deposition, airway wall area, airway smooth muscle thickness and lung pathology were also assessed. Atorvastatin treatment led to downregulation of tTG and TREM-1 expression in lung tissue after ovalbumin sensitization, blocked the activity of MMP-9, vascular endothelial growth factor, nuclear factor-κB p65, α-SMA, HIF-α and TGF-β1 and up-regulated Nrf2 expression. Furthermore, the number of lymphocytes and eosinophils in the atorvastatin group was significantly lower than that in the control group. In addition, airway hyperresponsiveness, lung collagen deposition, airway wall area, airway smooth muscle thickness and pathological changes in the lung were significantly decreased in the atorvastatin group, and tumor necrosis factor-α, interleukin (IL)-8, IL-13 and IL-17 in serum were significantly decreased. Histological results demonstrated the attenuating effect of atorvastatin on ovalbumin-induced airway remodeling in asthma. In conclusion, the present study indicated that atorvastatin significantly alleviated ovalbumin-induced airway remodeling in asthma by downregulating tTG and TREM-1 expression. The marked protective effects of atorvastatin suggest its therapeutic potential in ovalbumin-induced airway remodeling in asthma treatment.