Modulação da via das quinureninas na lesão auricular aguda induzida pela radiação UVB em camundongos

Abstract

Ultraviolet (UV) B radiation in the epithelial tissue stimulates the synthesis and release of pro-inflammatory mediators, inducing the infiltration and activation of neutrophils and other phagocytic cells. Thus, inflammatory processes caused by UVB radiation can be harmful to various cells in the body, from photoaging to immonussuppression. Tryptophan (TRYP) is an essential amino acid, used in numerous physiological processes and metabolized by two main pathways, serotoninergic and kynurenines. The latter is related to the indoleamine 2,3 dioxygenase (IDO) enzyme that can be induced by inflammatory processes increasing the consumption of TRYP and forming oxidative metabolites, such as the quinolinic acid that is related in the process of immunotolerance. Due to the involvement of the IDO enzyme and its possible therapeutic target, the objective of this work was to evaluate the production of metabolites of the kinurenins pathway (KPs) in mice ear lesions caused by 24-hour UVB exposure to the IDO enzyme inhibitor 1-methyl tryptophan (1-MT). The experiments were performed with 30 animals of the C57B / 6J lineage. After being divided into five groups of six animals called: a) control, without exposure to UVB radiation; B) vehicle, exposed to UVB radiation treated with saline (10μL); C) exposed to UVB radiation and treated with 1-MT enzyme inhibitor (0,5 μg/μl); D) exposed to UVB radiation and treated with 1-MT enzyme inhibitor (1,0 μg/μl) and group e) exposed to UVB radiation and treated with 1-MT enzyme inhibitor (2,0 μg/μl). Treatment with 1-MT and the vehicle were performed topically prior to exposure to UVB radiation, and 24 hours after exposure, the mice were euthanized and the ears fully extracted for specific dosages. The present study demonstrated that 1-MT 9 treatment against UVB radiation in mouse ear lesions was effective in attenuating the following alterations, the thickness and inflammation of the irradiated ears, the oxidative stress caused by UVB radiation in the ears of the mice. It decreased levels of tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), interferon gamma (INF-γ), interleukin 13 (IL-13), interleukin 17 (IL-17), interleukin-10 (IL-10) and nuclear factor kappa B (NF-κB), reducing levels of inflammatory cytokines. Increased TRIP levels at the site, thereby decreasing its metabolites such as kynurenine (KYN), kynurenic acid (KYNA), 3-Hydroxyquinurenine (3-HK), 3-hydroxyanthranilic acid (3-HAA), anthranilic acid (AA) e quinolinic acid (QA). Increased activities of the enzymes involved in KPs, including IDO, kynurenine 3-monoxygenase (KMO), kynurenine aminotransferase (KAT) and kynureninase (KYNU). In conclusion, these results demonstrate that inhibition of the IDO enzyme caused attenuation of inflammation, oxidative stress and metabolites of KPs. In addition, they suggest that the inhibition of this enzyme, either with synthetic or natural products may provide a new therapeutic approach for the treatment and prevention of injuries caused by UVB radiation on the skin.