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.

Aurintricarboxylic acid structure modifications lead to reduction of inhibitory properties against virulence factor YopH and higher cytotoxicity

Yersinia sp. bacteria owe their viability and pathogenic virulence to the YopH factor, which is a highly active bacterial protein tyrosine phosphatase. Inhibition of YopH phosphatase results in the lack of Yersinia sp. pathogenicity. We have previously described that aurintricarboxylic acid inhibits the activity of YopH at nanomolar concentrations and represents a unique mechanism of YopH inactivation due to a redox process. This work is a continuation of our previous studies. Here we show that modifications of the structure of aurintricarboxylic acid reduce the ability to inactivate YopH and lead to higher cytotoxicity. In the present paper we examine the inhibitory properties of aurintricarboxylic acid analogues, such as eriochrome cyanine R (ECR) and pararosaniline. Computational docking studies we report here indicate that ATA analogues are not precluded to bind in the YopH active site and in all obtained binding conformations ECR and pararosaniline bind to YopH active site. The free binding energy calculations show that ECR has a stronger binding affinity to YopH than pararosaniline, which was confirmed by experimental YopH enzymatic activity studies. We found that ATA analogues can reversibly reduce the enzymatic activity of YopH, but possess weaker inhibitory properties than ATA. The ATA analogues induced inactivation of YopH is probably due to oxidative mechanism, as pretreatment with catalase prevents from inhibition. We also found that ATA analogues significantly decrease the viability of macrophage cells, especially pararosaniline, while ATA reveals only slight effect on cell viability.