Effect of oleanolic acid for prevention of acute lung injury and apoptosis

Abstract

Background: This study aims to evaluate the efficiency of oleanolic acid on acute lung injury and acute respiratory distress syndrome.

Methods: The study included 70 female Wistar albino rats (weighing 180 to 200 g). We created seven groups, each consisting of 10 rats. Then, we generated acute lung injuries by intra-tracheal peroxynitrite injection in every group except for the control group. We investigated the effect of oleanolic acid. For this purpose, we measured the levels of malondialdehyde, interleukin 1 beta, interleukin 4, interleukin 10 and tumor necrosis factor alpha in the collected blood samples from the rats. In addition, we examined the lung tissue samples histopathologically and assessed the rate of apoptosis.

Results: Peroxynitrite injected groups at 24 and 48 h showed a statistically significant increase in interleukin 1 beta, tumor necrosis factor alpha, interleukin 4, interleukin 10 and malondialdehyde levels, which are accepted as mediators of the inflammatory process, compared to the control group. When peroxynitrite injected groups at 24 and 48 h were compared to the treatment groups of the same hour, a statistically significant decrease was detected. According to histopathological examination, peroxynitrite injected groups at 24 and 48 h showed a significant increase of tissue injury scores compared to the control group. However, the groups that were treated with oleanolic acid showed a significant decrease compared to the peroxynitrite groups (p<0.001 for tumor necrosis factor alpha and apoptosis results at 48 h).

Conclusion: In this study, we confirmed that oleanolic acid can be an effective agent for the prevention of acute lung injury generated via peroxynitrite.

Keywords: Acute lung injury; acute respiratory distress syndrome; oleanolic acid; peroxynitrite.

Figure 1. (a) Normal lung histology, score 1 (H-E x20). (b) Perivascular minor neutrophil infiltration in lung, score 2 (H-E x20). (c) Perivascular neutrophil infiltration and edema fluid in lung, score 3 (H-E x20). (d) Intensive neutrophil infiltration, abscess intraalveolar exudates, fibrosis of small airways walls, and epithelial desquamation in lung, score 4 (H-E x20).

Figure 2. Parenchymal damage scores (H-E). C: Control group; P24: Peroxynitrite 24th h group; POB24: Peroxynitrite and bronchoalveolar lavage oleanolic acid 24th h group; POI24: Peroxynitrite and intraperitoneal oleanolic acid 24th h group; P48: Peroxynitrite 48th h group; POB48: Peroxynitrite and bronchoalveolar lavage oleanolic acid 48th h group; POI48: Peroxynitrite and intraperitoneal 48th h oleanolic acid group; Score 1: Normal histology; Score 2: Minor neutrophilic infiltration; Score 3: Moderate neutrophilic infiltration, perivascular edema, mild fibrosis; Score 4: Intensive neutrophilic infiltration, abscess formation, marked fibrosis. The most tissue damage is seen in P48 groups. In treatment groups at 48 h (POI48 and POB48), there is a significant decrease in pathology scores.

Figure 3. Lung tissue ApopTag staining results. C: Control group; P24: Peroxynitrite 24th h group; POB24: Peroxynitrite and bronchoalveolar lavage oleanolic acid 24th h group; POI24: Peroxynitrite and intraperitoneal oleanolic acid 24th h group; P48: Peroxynitrite 48th h group; POB48: Peroxynitrite and bronchoalveolar lavage oleanolic acid 48th h group; POI48: Peroxynitrite and intraperitoneal 48th h oleanolic acid group; Lung tissue mean apoptotic cell count in high power fields. The most apoptotic cell count is in P48 group and there is a significant decrease in treatment groups (POI48 and POB48).