Therapeutic effects of Hedyotis diffusa Willd in a COPD mouse model challenged with LPS and smoke

Abstract

Hedyotis diffusa Willd (HDW) is a constituent of several Chinese medicines used clinically to treat inflammatory diseases, including airway inflammation. The aim of the present study was to investigate whether HDW serves a protective role in suppressing chronic airway inflammation and its underlying mechanisms. A mouse model of chronic smoking was induced via exposure to cigarette smoke (CS) for 30 days, increasing the exposure time for up to 5 min per day and the administration of lipopolysaccharide (LPS). Mice were gavaged with HDW (50 or 100 mg/kg body weight), dexamethasone (1 mg/kg body weight) or normal saline (NS, 0.9%) 1 h prior to CS challenge. Compared with CS and LPS (SL)-induced mice, the levels of interleukin (IL)-1β, tumor necrosis factor-α and transforming growth factor-β in bronchoalveolar lavage fluid from HDW+SL mice were significantly decreased and IL-10 was markedly reduced. Histological examination of the lung tissues revealed that HDW treatment alleviates airway inflammation. In addition, the administration of HDW to human bronchial epithelial BEAS-2B cells suppressed the activity of the nuclear factor (NF)-κB signaling pathway. The results of the present study demonstrate that HDW has a therapeutic effect in COPD and the underlying mechanism may be attributed to inhibition of the NF-κB pathway.

Keywords: Hedyotis diffusa Willd; airway inflammation; chronic obstructive pulmonary disease; nuclear factor-κB.

Figure 1.

High performance liquid chromatography-mass spectrometry extracted ion chromatograms of ferulic, oleanolic and ursolic acids.

Figure 2.

Effects of HDW on airway inflammation in a mouse model of chronic obstructive pulmonary disease. (A) Histological examination of mouse lung (n=6 per group) was performed 24 h following final SL stimulus. Formalin-fixed lung tissues were sectioned at a thickness of 3 µm and stained with hematoxylin and eosin. (B) Semiquantitative scoring of airway inflammation. Magnification, ×200. **P<0.01 vs. control and ^#P<0.05 vs. SL. Control, saline-treated mice; SL, cigarette smoke+lipopolysaccharide-challenged mice; HDW, Hedyotis diffusa Willd; DEX, dexamethasone (1 mg/kg).

Figure 3.

Effect of HDW on inflammatory cells in BALF. BALF was harvested from mice 24 h following final SL stimulus and the number of inflammatory cells was counted. (A) Total white blood cell count, (B) neutrophil count (C) eosinophil count and (D) macrophage count. *P<0.05 vs. control and ^#P<0.05 vs. SL. Control, saline-treated mice; SL, cigarette smoke+lipopolysaccharide-challenged mice; HDW, Hedyotis diffusa Willd; BALF, bronchoalveolar lavage fluid; DEX, dexamethasone (1 mg/kg).

Figure 4.

Effect of HDW on cytokine levels in BALF. BALF was harvested from mice 24 h following final SL stimulus and centrifuged to obtain the supernatant. Levels of (A) IL-1β, (B) TNF-α, (C) TGF-β in BALF and (D) IL-10 in BALF were measured using ELISA. *P<0.05 vs. control and ^#P<0.05 vs. SL. Control, saline-treated mice; SL, cigarette smoke+lipopolysaccharide-challenged mice; HDW, Hedyotis diffusa Willd; BALF, bronchoalveolar lavage fluid; DEX, dexamethasone (1 mg/kg).

Figure 5.

Effect of HDW on NF-κB activity and cellular proliferation in BEAS-2B cells. (A) Cells were pretreated with HDW (20, 10, 1 or 0.1 µmol/l) for 1 h and then treated with LPS (10 µg/ml) or D-Hanks for 30 min. Western blotting was performed to assess the phosphorylation of IκBα. (B) Cells were pretreated with HDW (20, 10, 1 or 0.1 µmol/l) for 1 h and then treated with LPS (10 µg/ml) or D-Hanks for 24 h. Western blotting was performed to assess nuclear NF-κB/p65 expression. (C) The inhibition rates of BEAS-2B cells treated with HDW (20, 10, 1 or 0.1 µmol/l) were detected using Cell Counting Kit-8 assays. HDW, Hedyotis diffusa Willd; NF-κB, nuclear factor-κB; LPS, lipopolysaccharide; IκBα, inhibitor of NF-κB; phospho, phosphorylated.