Aurintricarboxylic acid mitigates cigarette smoke extract induced oxidative stress and pulmonary inflammation via inhibition of NF-ҡB/p65 signaling

Cigarette smoke (CS) induced emphysema and chronic pulmonary inflammation are major comorbidities of chronic obstructive pulmonary disease (COPD), a major cause of morbidity and mortality worldwide. CS exposure exacerbates pulmonary inflammation and compromises immunity to various infections. Aurintricarboxylic acid (ATA) is a polyanionic aromatic compound especially recognized for its anti-inflammatory, nucleic acid, and protein interaction inhibition properties. The study was designed to investigate the anti-inflammatory role of ATA against cigarette smoke extract (CSE) induced pulmonary inflammation. Nicotine concentration was quantified in CSE by UPLC/MS technique. In vitro, fluorescence microscopy, and flow cytometry was performed in CSE stimulated alveolar epithelial cells to determine the effect of ATA on oxidative stress-mediated cellular apoptosis. In vivo, pulmonary inflammation was induced in male Wistar rats via a modified non-invasive intratracheal instillation of cigarette smoke extract (100 µl/animal) twice a week for 8 weeks and post-treated with ATA (10 mg/kg) intraperitoneally for 15 days. Lung homogenates were assessed for MDA and GSH. Lung tissues were subjected to western blotting and histopathological analysis. As result, ATA reduced CSE-induced chromatin condensation, fragmentation, cellular apoptosis in alveolar epithelial cells, and apoptotic biomarkers expression including BAX and Caspase-3 in the lungs. ATA reduced inflammation by normalizing redox balance reflected by MDA/GSH levels. ATA obviated airspace enlargement, fiber deposition, and immune cell infiltration. Reduced inflammation was accompanied by inhibition of inflammatory biomarkers TNF-α, TNFR1, TWEAK, and NF-ҡB/p65 activation and nuclear translocation. ATA efficaciously diminished the oxidative stress and pulmonary inflammation associated with lung pathogenesis through TNF-α/TNFR1/NF-ҡB/p65 signaling pathway. HIGHLIGHTSATA treatment attenuates CSE-stimulated chromatin condensation, fragmentation, and cellular apoptosis in alveolar epithelial cells.ATA treatment inhibits CSE stimulated activation and nuclear translocation of NF-ҡB/p65.ATA treatment diminishes CSE-induced oxidant injury, apoptosis, and emphysema-like phenotypic changes in the lungs.ATA inhibits lung inflammation via suppression of the NF-ҡB/p65 signaling pathway.

Ethanolic Extract of Tridax procumbens Mitigates Pulmonary Inflammation via Inhibition of NF-κB/p65/ERK Mediated Signalling in an Allergic Asthma Model

BACKGROUND

Tridax procumbens is a traditionally used medicinal plant with high content of active phytoconstituents having anti-inflammatory activity. Accumulating evidences have shown that Tridax procumbens efficaciously diminished oxidative stress and inflammation. However the anti-inflammatory role of Tridax procumbens is not obscured in allergic asthma.

PURPOSE

Aim of this study was to decipher the anti-inflammatory role of Tridax procumbens in allergic asthma and its underlying mechanism.

METHODS

Ethanolic extract of Tridax procumbens (TP) was prepared and major phytoconstituents (flavonoids) were characterized by biochemical and UPLC/MS analysis. Rats were sensitized and challenged with environmental allergen ovalbumin (OVA) and lipopolysaccharide (LPS) to establish an allergic asthma model. Persuasive anti-inflammatory role of TP was demonstrated in vivo (100, 200 and 400 mg/kg) and in vitro (250, 125, 75 and 25 µg/ml) experiments.

RESULTS

Characterization by UPLC/MS analysis showed the presence of various bioactive flavonoids. In in vitro study, significant reduction in ROS production, apoptosis and mitochondrial dysfunction were observed in alveolar type II cells upon pre-treatment with TP (250, 125, 75 and 25 µg/ml) in a concentration-dependant manner. In vivo, TP (200 mg/kg) oral administration showed robust anti-oxidative activity. TP treatment abrogated bronchial wall thickening, immune cell infiltration and bronchial wall fibre deposition. Immunohistochemical analysis showed the diminished expression of IL-1β, IL-6 in bronchial epithelium and vascular endothelium. TP abrogated inflammation by reducing the level of inflammatory cytokines including IL-2, IFN-γ, IL-6 and MCP-1, as well as inflammatory markers including TWEAK, TNF-α, TNF-R1 and its downstream transcription factor NF-ҡB/p65 activation and its nuclear translocation. Western blot analysis of TP treated lung tissue and alveolar type II cells showed reduced phosphorylation of ERK1/2 significantly.

CONCLUSION

TP exhibited anti-inflammatory activity by inhibition of ROS production and down-regulation of NF-ҡB/ERK signalling in vitro and in vivo asthma model. Thus, TP can be envisaged as an effective anti-inflammatory agent for OVA-induced allergic asthma.