Estudo dos receptores canabinoides na ativação de neutrófilos durante a lesão aguda pulmonar induzida por malária

Abstract

The inflammatory response plays a crucial role in the progression of severe manifestations in malaria. Neutrophils are key cells in the development of malaria-associated lung injury (MA-ALI/ARDS) and are considered targets for attenuating infectious inflammatory processes. Type 1 (CB1R) and type 2 (CB2R) cannabinoid receptors have been investigated as possible anti-inflammatory therapeutic targets. Although studies have addressed the modulation of these receptors in the innate immune system, especially in neutrophils, the mechanisms of activation of these cells by CB1 and CB2 receptors have not yet been completely elucidated. The objective of this work was to evaluate the impact of modulating cannabinoid receptors on the activation of neutrophils and the development of severe pulmonary malaria. Our results demonstrate that the activation of CB2R, through its selective agonist, JWH133 (10 µM), in human neutrophils stimulated in vitro with IL-8 (25 ng/mL), induced a significant reduction in migration and the release of inflammatory mediators (NO and TNF-α). Furthermore, CB2R activation inhibited the release of NETs and ROS in neutrophils stimulated with PMA (5 nM). In contrast, CB2R activation in neutrophils stimulated with TNF-α (10 ng/mL) and IL-8 (25 ng/mL) resulted in increased release of NETs and ROS, as well as indicating a possible increase in the survival of these neutrophils. These results suggest that the actions resulting from CB2R activation are stimulus dependent. In in vivo experiments, P. berghei NK65 infection was associated with increased production of inflammatory mediators, such as TNF-α and CXCL-1/KC, and the promotion of neutrophil activation and efflux from the bone marrow into the bloodstream. Ex vivo analysis revealed greater chemokinesis in neutrophils isolated from infected animals, while plasma from these animals induced neutrophil chemotaxis. Pretreatment with JWH133 (0.25, 0.5, and 1 mg/kg) in C57/BL6 mice infected by P. berghei NK65 did not change parasitemia. However, the dose of 0.5 mg/kg increased the relative lung weight and total peripheral leukocyte count, despite reducing pulmonary edema. In turn, the dose of 0.25 mg/kg reduced the circulating neutrophil count. These results indicate that JWH133 appears to modulate some parameters of severe pulmonary malaria and the influx of neutrophils into peripheral blood.Taken together, our data highlight the importance of CB2R activation in the effector actions of isolated neutrophils and during the development of severe experimental pulmonary malaria.