Efeito anti-inflamatório do ácido p-cumárico no modelo murino de lesão pulmonar aguda induzido por lipopolissacarídeo

Abstract

Acute lung injury (ALI) persists as a significant clinical problem responsible for a high mortality rate due to factors that include, among other things, the absence of effective therapies in clinical practice. Previous studies have reported that p-coumaric acid (CA), a phenolic compound, possesses relevant pharmacological properties including antioxidant effect and immunomodulatory activity. However, its effect on lung inflammation remains unknown. Therefore, in this study, we sought to evaluate the effect of p-coumaric acid on acute lung injury induced by lipopolysaccharide (LPS). To do so, male Swiss mice (30 g) were intranasally exposed to CA (0.1 or 1 μg/Kg) 1 h prior LPS stimulation (10 μg/mice) for inducing ALI. At 12 h after LPS stimulation, bronchoalveolar lavage fluid (BAL) was collected to determine the number of inflammatory cells and the quantification of cytokines, while the lung was used for histopathological analysis through H&E staining. The levels of interleukin (IL)-6, IL-8 and IL-10 were measured in the BAL, while in the lung tissue levels of IL-6 and IL-10, were evaluated by ELISA. In another set of experiments, an in vitro approach was performed to evaluate the effect of CA on the viability of human neutrophils and neutrophils adhesion to vascular endothelial cells. To this end, human neutrophils with or without CA pretreatment were allowed to adhere in TNF-α-stimulated (10 ng/mL) vascular endothelial cells (EA.hy926 cells). In this experiment, the number of adhered neutrophils per endothelial cell was determined by direct counting. The one-way ANOVA followed by post hoc Newman-Keuls test was used for statistical evaluation between experimental groups with P<0.05 considered significant. As a result, LPS stimulation increased both total leukocyte counts (p<0.01) and neutrophils count in BAL, phenomena that were decreased by pretreatment with CA. In addition, treatment with 1 μg/kg of CA decreased levels of IL-6 and IL-8, at the same time that markedly increased levels of IL-10 in BAL fluid. The same was observed in lung tissue with levels for IL-6 and IL-10. When evaluating lung parenchyma, it was observed that, in comparison to the LPS-stimulated group, inflammatory cells infiltration around the bronchi was significantly declined with CA pretreatment (p<0.001). In vitro analyzes revealed that pretreatment with p-coumaric acid was able to reduce the index of adhesion neutrophil to TNF-activated endothelial cells (p<0.001), without interfering with neutrophil viability. These results show for the first time that CA when administered topically can suppresses the inflammation triggered by LPS-induced lung injury through reducing the production of proinflammatory cytokines IL-6 and IL-8 and stimulating the production of the anti-inflammatory cytokine IL-10. The anti-inflammatory effects of CA also extended to the lung tissue, since histopathological changes caused by LPS were also attenuated. In addition, CA was able to interfere with the adhesion of neutrophils to the endothelium. Taken together, these results suggested that CA might be useful in the therapy of acute lung injury.