ABSTRACT
Inhibiting reactive oxygen species (ROS) has been viewed as a therapeutic target for the treatment of acute lung injury (ALI). Osthole, an active component in Chinese herbal medicine, has drawn increasing attention because of its various pharmacological functions, including anti-inflammatory and anti-oxidative activities. The aim of the present study was to examine the effects of osthole on ALI induced by lipopolysaccharide (LPS) through intratracheal instillation. The mRNA and protein expression levels of thioredoxin 1 (Trx1) and the nuclear factor erythroid-2 related factor 2 (Nrf2) were detected by real-time PCR, reverse transcription PCR (RT-PCR) and Western blot, respectively. ROS production was measured by flow cytometry. Our results showed that osthole treatment improved the mice survival rates in the middle and high dosage groups, compared with the untreated LPS group. Moreover, osthole treatment significantly improved LPS-induced lung pathological damage, and it decreased the lung injury scores, lung wet/dry ratios and the total protein level in Bronchoalveolar lavage fluid (BALF). Osthole treatment dramatically reduced the H2O2, MDA and OH levels in the lung homogenates. LDH and ROS were markedly reduced in the osthole+LPS group in vitro. Furthermore, osthole increased Nrf2 and Trx1 expression in terms of mRNA and protein in vivo and in vitro. Nrf2 siRNA (siNrf2) could suppress the beneficial effects of osthole on ALI. In conclusion, the current study demonstrates that osthole exerted protective effects on LPS-induced ALI by up-regulating the Nrf-2/Trx-1 pathway.
Subject(s)
Acute Lung Injury/drug therapy , Calcium Channel Blockers/therapeutic use , Coumarins/therapeutic use , NF-E2-Related Factor 2/metabolism , Thioredoxins/metabolism , Up-Regulation/drug effects , Acute Lung Injury/chemically induced , Acute Lung Injury/metabolism , Acute Lung Injury/mortality , Animals , Bronchoalveolar Lavage Fluid , Calcium Channel Blockers/pharmacology , Cell Line, Transformed , Cell Survival/drug effects , Coumarins/pharmacology , Disease Models, Animal , Dose-Response Relationship, Drug , Lipopolysaccharides/toxicity , Male , Mice , Mice, Inbred BALB C , NF-E2-Related Factor 2/genetics , Organ Size/drug effects , Oxidative Stress/drug effects , RNA, Messenger/metabolism , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , Reactive Oxygen Species/metabolism , Statistics, Nonparametric , Survival Analysis , Thioredoxins/genetics , Time Factors , TransfectionABSTRACT
The renin-angiotensin-aldosterone system (RAAS) plays an important role in the pathogenesis of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Angiotensin converting enzyme 2 (ACE2) plays a protective role in acute lung injury. Osthole, a natural coumarin derivative extracted from traditional Chinese medicines, is known to have anti-inflammatory effect, but the effect of osthole on the ALI is largely unknown. The aim of this study is to explore whether and by what mechanisms osthole protects lipopolysaccharide(LPS)-induced acute lung injury. Herein, we found that osthole had a beneficial effect on LPS-induced ALI in mice. As revealed by survival study, pretreatment with high doses of osthole reduced the mortality of mice from ALI. Osthole pretreatment significantly improved LPS-induced lung pathological changes, reduced lung wet/dry weight ratios and total protein in BALF. Osthole also inhibited the release of inflammatory mediators TNF-α and IL-6. Meanwhile, osthole markedly prevented the loss of ACE2 and Ang1-7 in lung tissue of ALI mice. ACE2 inhibitor blocked the protective effect of osthole in NR 8383 cell lines. Taken together, our study showed that osthole improved survival rate and attenuated LPS-induced ALI and ACE2 may play a role in it.
