Investigação dos mecanismos celulares e moleculares da ação anti-inflamatória do dipeptídeo cíclico glicina-prolina (CGP)

Abstract

Although often beneficial, the inflammatory process is closely involved in the pathophysiology of several diseases. The use of anti-inflammatory drugs available on the market is still a problem for patients, as the prolonged use is associated with severe side effects. Therefore, is relevant to identify new molecules with therapeutic potential for the treatment of inflammatory disorders. Cyclic peptides have attracted interest from the pharmaceutical industry for drug development that more than 40 cyclic peptide-based drugs have been approved by the FDA for clinical use in the past decade. In addition to neuroprotective effects, the cyclic dipeptide cyclo (Glycine-Proline, CGP), has been described by our research group as having analgesic and anti-inflammatory effects by inhibiting hypernociception and the accumulation of leukocytes in inflamed tissue. From these results, our main objective was to identify cellular and molecular targets that could account for the anti-inflammatory action of CGP. Initially, we found that GCP does not present cytotoxicity in all tested concentrations (10-300 μM). Our results also showed that CGP significantly inhibited the adhesion of neutrophils to endothelial cells at all concentrations tested (10-50 μM). We verified that CGP did not affect the expression of ICAM-1 and E-selectin. Similarly, CGP also did not significantly affect the production of IL-6, IL-8, IL-12p70 and reactive oxygen species (ROS) by endothelial cells stimulated with TNF-α. When assessing the motility the endothelium, our results show that CGP did not affect cell migration. However, CGP induced a significant increase in calcium influx in endothelial cells stimulated with histamine, a phenomenon that was not observed when cells were stimulated with CGP alone. In this regard, evaluating the competition of CGP for binding to receptors coupled to protein G was evaluated by the NanoBRET technique, we found that CGP promoted an increase in the interaction between H1 and β2 receptors and their respective natural ligands, a phenomenon that was not observed for other receivers, such as A1, A2A, A2B, A3, VEGFR2, CXCR4 and CXCR7. Taken together, we demonstrated, for the first time, that CGP may interact with H1 and β2 receptors and their ligands in which it may be associated with the effects of this dipeptide on the endothelium.