Inhalation of Essential Oil from Mentha piperita Ameliorates PM10-Exposed Asthma by Targeting IL-6/JAK2/STAT3 Pathway Based on a Network Pharmacological Analysis

Abstract

Fine particulate matter (PM) exposure exhibits a crucial risk factor to exacerbate airway epithelial remodeling, fibrosis, and pulmonary destruction in asthma. Based on the use of essential oils from aromatic plants on pain relief and anti-inflammatory properties, we investigated the inhibitory effects of essential oil derived from the Mentha species (MEO) against asthma exposed to PM10. The MEO (0.1 v/v %) was aerosolized by a nebulizer to ovalbumin and PM10-induced asthmatic mice. Histological changes were confirmed in the lung tissues. To define the mode of action of the MEO on asthma, a protein-protein interaction network was constructed using menthol and menthone as the major components of the MEO. Cytokine expression and the JAK2/STAT3 signaling pathway were analyzed in lung epithelial A549 cells co-treated with MEO and PM10. Inhalation of MEO by nebulization inhibited respiratory epithelium hyperplasia, collagen deposition, and goblet cell activation in asthmatic mice. Through a network pharmacological analysis, cytokine-cytokine receptor interaction and JAK/STAT was expected to be underlying mechanisms of MEO on asthma. Treatment with MEO significantly reduced the IL-6 levels with a decrease in pro-inflammatory and T helper 2-specific cytokines. PM10-induced phosphorylation of JAK2 and STAT3 was significantly decreased by MEO. Collectively, MEO may have an inhibitory effect on asthma under the condition of PM10 exposure through the IL-6/JAK2/STAT3 signaling pathway.

Keywords: Mentha essential oil; asthma; particulate matter; peppermint oil.

Figure 1

The structures of menthol and menthone, major components of Mentha essential oil (A). Protein–protein interaction network of Mentha essential oils (MEO) (B). The nodes and edges indicate the proteins and their relationships. Module extracted by Gene ontology enrichment analysis (C). The black nodes present seed nodes and the gray ones are nodes that interact with the seed nodes. Purple, Co-expression; Blue, Co-localization; Pink, Physical interactions; Yellow, shared protein domains; Orange, Predicted; Green, Genetic interactions; Sky, pathway.

Figure 2

Pathway analysis performed on the “Enrichr” platform. The enriched pathway terms are displayed in a bar graph (A). The length of the bar and the brightness of its color represent the significance of the specific pathway. Clustergram of pathways of MEO (B). Those clusters are ranked by p value. The colors of the boxes represent each cluster.

Figure 3

Histological changes of lung tissues stained by Hematoxylin and Eosin (A), Masson’s trichrome (B) and Periodic acid–Schiff (PAS) (C) in ovalbumin (OVA) and PM₁₀-exposed mice. Thickness of respiratory epithelium (D), collagen deposition % of area (E) and goblet cell number per area (F) were shown as relative quantified values. The slides of each mice (n = 7) were evaluated by randomly selecting 3 photographs and a total 21 images were quantified using Image J computerized densitometry system. Results are presented as mean ± standard error of the mean. ^### p < 0.001 vs. CTR group; * p < 0.05, ** p < 0.01 and *** p < 0.001 vs. PM₁₀ group.

Figure 4

The mRNA expressions of IL-6 (A), inflammatory cytokines including TNF-α, IL-1β, IL-5 and IL-8 (B), Th2-specific cytokines including IL-4 and IL-13 (C), and MMP-2 and MMP-9 (D) in PM₁₀-exposed A549 lung epithelial cells. The experiments were carried out in triplicate measurements. Results are presented as mean ± standard error of the mean. ^### p < 0.001 vs. non-treated cells; * p < 0.05, and *** p < 0.001 vs. PM₁₀-treated cells.

Figure 5

The protein expressions of JAK1 and JAK2 in PM₁₀-exposed A549 lung epithelial cells (A). The protein expression of STAT3 in PM₁₀-exposed A549 lung epithelial cells (B). The experiments were carried out in triplicate measurements. Results are presented as mean ± standard error of the mean. ^### p < 0.001 vs. non-treated cells; * p < 0.05, ** p < 0.01 and *** p < 0.001 vs. PM₁₀-treated cells.

Figure 6

The protein expressions of nuclear NF-κB, cytosolic NF-κB, and IκB-α in PM₁₀-exposed A549 lung epithelial cells. The experiments were carried out in triplicate measurements. Results are presented as mean ± standard error of the mean. ^### p < 0.001 vs. non-treated cells; * p < 0.05, ** p < 0.01 and *** p < 0.001 vs. PM₁₀-treated cells.

Figure 7

Schematic diagram of potential action of MEO on asthma under exposure of PM via inhibition of IL-6/JAK2/STAT3 pathway.