Papel da adenosina e da via PI3K/AKT/mTOR no efeito protetor do pré-condicionamento isquêmico remoto na formação de lesão por pressão experimental

Abstract

Pressure injury (PI) is a type of ischemia and reperfusion injury (I/R) that affects a considerable number of people worldwide, and the current major challenge is an effective and low-cost preventive method for this problem. Remote ischemic preconditioning (RIPC) has been increasingly highlighted as a simple and inexpensive method of preventing I/R injuries. Therefore, it is important to assess the effect of the PCIR on PI. The aim of the present study is to evaluate the protective effect of RIPC on the formation of experimental PI and to understand the role of adenosine, its receptors and PI3K/AKT/mTOR pathway in this process. Male Swiss mice were submitted to noninvasive experimental PI model. The work was developed in two stages, the first tested the best protection protocol by RIPC, and the second evaluated the possible mechanism of action involved in protection. In the first stage, the best RIPC protocol was evaluated through the lesion area, EWAT (Experimental Wound Assessment Tool) scale, histopathological scores for pressure lesion and MDA test (malondialdehyde). The parameters evaluated showed that the 4-day protocol was the most effective in preventing PI, being chosen to follow up for the second stage. To investigate the involvement of adenosine, the A1, A2A, A2B receptor antagonists and the adenenosine deaminase (ADA) inhibitor were administered prior to RIPC in animals submitted to PI. The lesion area, EWAT scale and histopathological scores were evaluated. The results show that adenosine is important in the effect of PCIR and that A2A and A1 receptors are probably involved. Furthermore, the participation of the PI3K / AKT / mTOR pathway through qPCR and immunofluorescence for these markers was investigated. RIPC performed on animals with PI increases the expression of PI3K gene and phospho-mTOR labeling, showing that the pathway is activated and that the A2A receptor antagonist inhibits this activation. In addition, markers such as p38MAPK and VEGF also had their expression inhibited by the effect of RIPC. The effect on nitrosative stress was seen by nitrotyrosine labeling, where the A2A antagonist also reversed the effect of RIPC. In conclusion, the data suggest that RIPC has protective effect upon PI and that adenosine is involved in this mechanism, possibly through A1 and A2A receptors, with A2A being more participatory in this mechanism, and that the PI3/Akt/mTOR pathway is possibly involved in the protective effect of PCIR through activation by adenosine.