Effects of metformin on methylglyoxal-induced oxidative stress and airway remodeling in the ova-induced allergic asthma model

RESUMO

INTRODUÇÃO: Methylglyoxal (MGO) is a highly reactive dicarbonyl species associated with diabetes and other diseases (1). MGO is a major precursor of the advanced glycation end-products (AGEs), which interacts with its receptor RAGE, triggering multiple intracellular signaling pathways, including increased production of pro-inflammatory mediators and reactive oxygen species (ROS) (2). Prolonged intake of MGO significantly potentiates both acute lung injury and allergic airways inflammation in mice (3). In the LPS-induced lung inflammation, oral treatment with the anti-hyperglycemic drug metformin significantly reduced the exacerbation by MGO of the airway inflammation, strongly suggesting that metformin acts by scavenging MGO from blood circulation (4). A previous study showed that metformin reduces the eosinophilic inflammation and Th2 markers in lungs of high-fat diet fed hyperglycemic mice (5). Here, we hypothesized that beneficial effects of metformin in mouse allergic lung inflammation take place partly due to MGO inactivation. Therefore, this study was carried out to evaluate the effect of metformin on the potentiation by MGO of ovalbumin (OVA)-induced mouse airways inflammation

OBJETIVOS: In the present study, we proposed chronically administering MGO to healthy mice, aiming to investigate the cellular and molecular mechanisms by which MGO potentiates allergic (asthma) conditions. Therefore, in lungs of mice challenged with ovalbumin (OVA), treated with metformin.

MÉTODOS: The study was approved by the Animal Use Ethics Committee (CEUA-UNICAMP; protocol No. 6081-1/2022). Male C57BL/6 mice received or did not receive 0.5% MGO in drinking water for 12 weeks. Metformin was administered in the last two weeks of MGO treatment (300 mg/kg, gavage). Mice were sensitized twice with OVA (100 μg, s.c) and two weeks later they were challenged intranasally with OVA (10 μg) twice a day. Bronchoalveolar lavage fluid (BAL) and lung tissues were collected to quantify airway cell infiltration and reactive oxygen species (ROS) levels, as well as mRNA expression of NADPH oxidase isoforms, as well as the expression of RAGE and MGO by immunohistochemistry technique.

RESULTADOS: The serum concentration of MGO achieved after 12 weeks of ingestion (20.6 ± 1.3 μg/ml) was higher than that of untreated mice (2.2 ± 0.14 μg/ml; P<0.05), which was significantly reduced by metformin treatment (3.5 ± 0.64 μg/ml; P<0.05) as well as the immunohistochemistry technique for MGO showed a higher expression of MGO in lung tissue (P<0.05) . In OVA-challenged mice, MGO treatment significantly increased the total number of inflammatory cells and eosinophils compared to control animals (P<0.05). In the lung tissue of mice treated with MGO, there was a significant increase in the total number of inflammatory cells and eosinophils (P<0.05), as well as an increase in collagen and goblet cell hyperplasia (P<0.05), NOX- 2, NOX-4, ROS and RAGE increased by 100%, 100%, 80% and 60%, respectively (P<0.05). In MGO-treated mice, metformin treatment normalized methylglyoxal-induced oxidative stress as well as airway inflammation and remodeling in mice.

CONCLUSÃO: Metformin reduces oxidative stress and airway remodeling in response to prolonged MGO ingestion in ova-induced mice, which may be due to direct MGO scavenging.

BIBLIOGRAFIA: 1. Schalkwijk C.G, et al. Physiol. Rev, (100): 407-461; 2020 2. Checa J and Aran J.M.. J Inflamm Res,13:1057-1073; 2020 3. Medeiros ML, et al. Int Immunopharmacol. 81:106254; 2020 4. Medeiros ML, et al. J Inflamm Res. 2;14:6477-6489; 2021 5. Calixto MC et al. PLOS ONE, (10):1-13; 2013

PALAVRA-CHAVE: metformin, methylglyoxal, oxidative stress