Estudio de la activación de mecanismos de muerte celular programada inducida por el uso de resveratrol en un modelo de artritis inducida por antígeno (AIA)

Zusammenfassung

Rheumatoid arthritis (RA) is one of the most common chronic and inflammatory diseases of the musculoskeletal system, capable of producing long-term joint damage associated with severe pain, progressive functional disability and even early death; in addition to the high socioeconomic costs that this entails. Although RA frequently shows systemic involvement, its main target is the synovial joints. Thus, the hyperplastic synovial membrane is one of its main pathological features, and it is associated both with the local infiltration and retention of inflammatory immune cells and with the activation and excessive proliferation of resident cells of the synovium. In relation to RA treatment, current drugs present numerous limitations, and consequently, in recent years, the possible therapeutic potential of natural products against this disease has been arousing great interest. In this line, the present work aimed to deepen the prophylactic effect of a compound of natural origin, such as resveratrol, in RA, using an animal model of antigen-induced arthritis in rats (AIA). To evaluate the effect of resveratrol in the in vivo study, it was administered orally during the two months prior to the induction of arthritis and continuing until the day of sacrifice, two days after induction, corresponding to the acute phase of the disease. In the first place, it was observed how resveratrol treatment was able to counteract the cardinal parameters of arthritic pathology (proliferation of the intimal layer, immune cellular infiltrate and cellularity) in the synovial tissue. In addition, it was evaluated how the possible involvement of two of the most relevant cell death mechanisms, type I cell death or apoptosis and/or type II cell death or autophagy, could play a fundamental role in the control of excessive cell proliferation of the synovial tissue of the arthritic joint. For this, the synovial expression of the active caspase-3 and its substrate PARP as intermediates of the apoptotic process and LC3, p62 and beclin-1 as mediators of the autophagic process were analyzed using immunohistochemical techniques; showing how resveratrol is capable of regulating the balance between autophagy and apoptosis, directing it towards autophagy and promoting, more specifically, the non-canonical pathway of autophagy. Furthermore, there is increasing evidence that a failure in autophagy could modulate inflammatory activity, promoting the development of multiple inflammatory and autoimmune diseases, such as RA. Thus, the serum concentration of three important mediators of inflammation at the systemic level, with great clinical relevance, was evaluated by means of immunoassays: interleukin (IL)-1β, prostaglandin (PG)E2 and C-reactive protein (CRP). The results obtained showed how those animals to which resveratrol was administered prophylactically had reduced levels of these markers; in the same way, when carrying out the correlation analysis between the levels of these and the synovial expression of p62, a strong positive correlation was obtained in all cases, highlighting the important relationship that autophagy maintains with the inflammatory process. Finally, the synovial expression of the transcription factor p65-NF-κB, key in the regulation of inflammation, and also of the markers VEGF and Ang-1, involved in the angiogenesis process, was evaluated, which contributed to obtaining a broader vision of the potential anti-inflammatory properties of resveratrol in the arthritic pathology. Our data showed that resveratrol down-regulated the expression levels of all these proteins in the synovial tissue of the animals in which arthritic disease was induced and, likewise, our results reflected the existence of a strong positive correlation between the synovial expression of p62 and factor p65-NF-κB. Based on the data obtained in the present work, we can suggest that the suppression of the inflammatory pathway, as a consequence of the inhibition of the transcription factor NF-ᴋB through the activation of the autophagic process, could be considered as a therapeutic strategy. The reason for this is due to the fact that a multitude of inflammatory mediators that are involved in its signaling pathway and that actively participate in the different events underlying RA are inhibited. To conclude, the data provided in this work suggest that the improvement of the autophagic process could be considered as a potential therapeutic target in the treatment of RA and, likewise, supports the use of compounds of natural origin, such as resveratrol, as a strategy in the treatment of this disease.