Protective effects of lavender oil on sepsis-induced acute lung injury via regulation of the NF-κB pathway

Abstract

Context: Lavender oil (Lav) from Lavandula angustifolia L. (Lamiacease) exhibits antioxidative and anti-inflammatory properties against various diseases.

Objective: The study explores the effect of Lav pre-treatment on sepsis-induced acute lung injury (ALI).

Materials and methods: Sprague-Dawley rats were assigned into Sham, caecal ligation and puncture (CLP), CLP + Lav (200, 400, and 800 mg/kg) groups. Lav was administered by gavage, once a day, for 7 days. Histological analysis was performed using haematoxylin and eosin staining. Cytokine and nitrite levels were detected by enzyme-linked immunosorbent assay kits and Griess reagent. Gene and protein expression were tested by quantitative real-time polymerase chain reaction and western blot.

Results: The levels of tumour necrosis factor-α (BALF: 64%, serum: 59%), interleukin (IL)-1β (BALF: 63%, serum: 66%) and IL-6 (BALF: 54%, serum: 59%), and nitrite (40%) and inducible nitric oxide synthase (51%), and the level of myeloperoxidase (66%) and malondialdehyde (59%), and cleaved-caspase 3 (84%) and Bax expression (74%) induced by CLP were decreased when given Lav. Additionally, the level of superoxide dismutase (211%) and glutathione (139%), and the expression of Bcl-2 (980%) induced by CLP were increased when given Lav. The increased p-nuclear factor (NF)-κB/NF-κB (72%) and p-inhibitor of κBα (IκBα)/IκBα (77%) induced by CLP could be reversed by Lav.

Discussion and conclusions: Lav pre-treatment might protect rats from sepsis-induced ALI via deactivation of the NF-κB pathway. Our research demonstrated the regulatory mechanisms of Lav in sepsis-induced ALI and can provide a theoretical basis for the use of Lav in the treatment of sepsis-induced ALI.

Keywords: Caecal ligation and puncture; apoptosis; inflammation; oxidative stress.

Figure 1.

Lav pre-treatment relieved sepsis-induced ALI in rats. (A and B) The histological changes of the collected lung tissues were tested by H&E staining and the lung injury was scored. (C) The wet/dry ratio of the right lung was determined. (D–F) Total protein content, total cell and neutrophil numbers in BALF were tested via BCA assay kit, blood counting chamber and Giemsa staining, respectively. *Represents comparation with the Sham group, while # represents comparation with the CLP group. **p < 0.01, ^#p < 0.05, ^##p < 0.01.

Figure 2.

Lav pre-treatment repressed inflammatory responses in sepsis-induced rats. (A–F) The levels of inflammatory cytokines (IL-1β, IL-6 and TNF-α) in the BALF and serum were tested via the appropriate ELISA kits. *Represents comparation with the Sham group, while # represents comparation with the CLP group. **p < 0.01, ^#p < 0.05, ^##p < 0.01.

Figure 3.

Lav pre-treatment attenuates sepsis-induced nitrosative stress in the lung tissues of rats. (A) The concentration of nitrite in the lung tissues was tested via Griess reagent. (B–D) The mRNA and protein levels of iNOS in the lung tissues were confirmed via qRT-PCR and western blot, respectively. *Represents comparation with the Sham group, while # represents comparation with the CLP group. **p < 0.01, ^#p < 0.05, ^##p < 0.01.

Figure 4.

Lav pre-treatment alleviated sepsis-induced oxidative stress in the lung tissues of rats. (A) The MPO activity in the lung tissues was measured via a myeloperoxidase assay kit. (B–D) The contents of MDA, SOD and GSH in the lung tissues were tested with their corresponding kit. *Represents comparation with the Sham group, while # represents comparation with the CLP group. **p < 0.01, ^#p < 0.05, ^##p < 0.01.

Figure 5.

Lav pre-treatment protected the lung tissues from sepsis-induced cell apoptosis. (A and B) Cell apoptosis in the lung tissues was determined via TUNEL assay. (C–F) Cell apoptosis-associated cleaved-caspase 3, Bcl-2 and Bax expression in the lung tissues was evaluated via western blot. *Represents comparation with the Sham group, while # represents comparation with the CLP group. **p < 0.01, ^#p < 0.05, ^##p < 0.01.

Figure 6.

Lav pre-treatment performed its protective effects on sepsis-induced ALI via deactivation of NF-κB pathway. (A and B) Venn diagram analysis and pathway analysis were carried out to determine the potential pathway that participated in the regulation of Lav in sepsis-induced lung injury. (C and D) The levels of NF-κB pathway-associated p-NF-κB, NF-κB, p-IκBα and IκBα were measured via western blot. (E and F) Immunohistochemistry was utilised for the evaluation of the level of p-NF-κB in the lung tissues. *Represents comparation with the Sham group, while # represents comparation with the CLP group. **p < 0.01, ^##p < 0.01.