Avaliação dos efeitos do ácido p-cumárico sobre células do epitélio alveolar humano: possível envolvimento do sistema antioxidante

Abstract

Introduction: Oxidative stress plays a role between the main mechanisms intricated with the pathogenesis of Chronic Obstructive Pulmonary Disease (COPD) and its intensity is directly associated with the severity of the disease. The participation of oxidative stress in COPD involves the amplification of the inflammatory response, impairment of anti-protease function, reduction of corticosteroid response and induction of apoptosis in alveolar epithelial cells. It is emphasized that COPD, whose main risk factor is exposure to cigarette smoke, is the third cause of mortality and morbidity in the world, mainly due to sudden worsening of symptoms (exacerbations), usually associated with opportunistic pathogen infections. In a context where the current pharmaceutical treatments are linked to various side effects, the p-coumaric acid (AC) emerges as a candidate molecule due to its antioxidant and anti-inflammatory properties. Therefore, this study aimed to evaluate the effects of AC in human alveolar epithelial cells (A549) activated with cigarette smoke extract (CSE) combined with LPS or with TNF-α. Methods: A549 cells were pretreated with AC and exposed to the EFC combined with LPS or with TNF-α. Cell viability after exposure to AC or EFC / LPS was evaluated by MTT assay. Reactive oxygen species (ROS) were measured by flow cytometry using DCFH-DA assay and gene expression of antioxidant enzymes were measured by sqRT-PCR. The data were submitted to ANOVA with Tukey post-test in Graphpad Prism software. Results: The EFC 5% and LPS 1 μg/ml alone were unable to increase A549 in the ROS, however combination of both made. The combined stimulus reduced the mRNA levels of catalase, that were not restored with pretreatment with the AC. However, pretreatment with AC decreased ROS independent of concentration. TNF-α was not able to induce oxidative stress but induced an increase in mRNA levels of glutathione peroxidase that was restored with CA pretreatment, in addition, there was an increase in the levels of SOD-1 and SOD- 2 when the cells were pretreated with CA and stimulated with TNF-α. Conclusion: These results support an antioxidant role of the AC in the face of ROS generated by exposed A549 cells to EFC combined with LPS or to TNF-α by mechanisms independent of antioxidant enzymes activation.