Bacterial respiratory tract inflammation in neonatal rat model is attenuated by benzofuran through inhibition of GATA3

Highlights

• Benzofuran treatment led to marked decrease in the airway resistance.

• It prevented accumulation of macrophages and inflammatory cells in the lung airways.

• The level of IFN-γ was increased by benzofuran in methacholine administered rats.

• Benzofuran prevented reduction in T-bet and up-regulation of GATA-3 in methacholine administered rats.

• Thus benzofuran can be of therapeutic importance for the treatment of asthma.

Abstract

The current study was aimed to investigate the effect of benzofuran on asthma neonatal rat model. Twenty-five neonatal rats were assigned into five groups; Normal control, untreated, 1 mg/kg, 8 mg/kg and 10 mg/kg treatment groups. Methacholine was administered orally to the rats of untreated and treatment groups. Animals in the normal control group were given PBS as a vehicle. FlexiVent system employing a computer-controlled mouse ventilator along with respiratory mechanics was used for the analysis of airway resistance in the rats. Cytokine level and IFN-γ in the rat serum samples was performed by ELISA in accordance with the instructions of manufacturer. Methacholine administration into the rats caused a marked increase in lung airway resistance. However, treatment with 8 and 10 mg/kg doses of benzofuran led to marked decrease in the airway resistance. Benzofuran treatment prevented accumulation of macrophages and inflammatory cells in the lung airways. Inhibition of inflammation in methacholine administered rats by benzofuran was also confirmed by hematoxylin & eosin-staining. Examination of the rat serum showed significantly higher level of Th2 cytokines (IL-4, -5 and -13) in the untreated rats. However, treatment of methacholine administered rats with benzofuran significantly inhibited Th2 cytokine expression. The level of IFN-γ was increased by benzofuran treatment in methacholine administered rats. In methacholine administered rats the level of IgE was markedly higher however treatment of asthma rats with benzofuran inhibited up-regulation of IgE significantly. The expression of T-bet is decreased and that of GATA-3 is increased by methacholine administration in the rat lungs. Benzofuran treatment of methacholine administered rats prevented reduction in T-bet and up-regulation of GATA-3 expression in the rat lungs. The effect of benzofuran was significant at the doses of 8 and 10 mg/kg and non-significant at 1 mg/kg. These finding suggest that benzofuran inhibits expression of dominant T-helper 2 cytokines through targeting GATA-binding protein 3 transcription factor. Thus benzofuran can be of therapeutic importance for the treatment of asthma.

Introduction

Bacterial respiratory tract inflammation is a heterogeneous and chronic disease of respiratory tract involving inflammation of lung airways and problem in breathing. Moreover, asthma is characterised by the production of excessive airway mucus and higher level of serum immunoglobulin E (IgE). Globally 1–18% of the population is suffering from asthma and are being treated using corticosteroids [1]. Studies have revealed that Type 2 inflammation which plays important role in asthma pathogenesis is the result of Th (T helper)2, Th17 and regulatory T (Treg) cells [2]. Treg cells constitute a type of CD4⁺ T cells and play an important role in the prevention of inflammation and immune tolerance [3]. The immune suppressive action of Treg cells is mediated by the expression of Forkhead box protein 3 (FOXP3) [4]. Treg cells inhibit the proinflammatory cytokine activation as well as suppress Th2 cell proliferation [5]. Thus Treg cells play a vital role in the asthma development by inhibiting Th2 cell activation, inflammatory cell infiltration and targeting IgE production [3].

Th2 cells express interleukin (IL)-4, −5 and −13 which are reported to be associated with development and progression of asthma. Th2 cells undergo differentiation in the presence of GATA-binding protein 3 (GATA-3) transcription factor which belongs to the zinc finger protein family [6]. Expression of GATA-3 is controlled by T cells through the involvement of T-bet. It is reported that T-bet inhibits production of IL-4 and promotes expression of interferon (IFN)-γ [7].

Natural as well as synthetic compounds containing benzofuran possess range of biological activities. They act as antimicrobial [8,9], anti-cancer [10], anti-inflammatory [11], antihyperglycemic and kinase inhibitor agents [12,13]. In addition, spirobenzofuran is the pharmacophore in several pharmaceutically significant compounds which exhibit broad spectrum of activities [14,15]. The present study was designed to discover effective treatment strategy and understand the mechanism of asthma fully. Herein, the effect of benzofuran (Fig. 1) on bacterial respiratory tract inflammation rat model was investigated. It was observed that benzofuran inhibits expression of dominant T-helper 2 cytokines through targeting GATA-binding protein 3 transcription factor. Thus benzofuran can be of therapeutic importance for the treatment of asthma.