Efeitos da exposição crônica ao mercúrio em pescadores do Complexo Lagunar Mundaú-Manguába (CELMM) e em modelo animal hipercolesterolêmico

Abstract

Mercury is a toxic metal that can cause environmental damage, and when human exposure to these contaminants occurs, it can lead to oxidative stress that may cause or exacerbate various morbidities. In the state of Alagoas, Mundaú Lagoon, which is part of the Mundaú-Manguaba Estuarine Complex (CELMM), is an important source of subsistence for the local population. However, according to recent data from our group, contamination by heavy metals, notably mercury (Hg), has been causing damage throughout the chain dependent on this environment, including the blood cells of fishermen from this locality. Therefore, one of the objectives of our work was to evaluate, in people living around the CELMM, functional and structural alterations of blood cells, as well as their redox status. Within the same context of Hg contamination, there is a relationship between blood Hg levels and the development of cardiovascular diseases. In the scope of cardiovascular diseases, atherosclerosis is one of the leading causes of death worldwide, which can lead to acute myocardial infarction. Thus, we used LDL receptor knockout mice (LDLr-/-) as a study model, which consequently have increased circulation of such cholesterol-rich lipoprotein, leading to atherosclerotic plaque formation. In these LDLr-/- animals, we evaluated whether treatment with HgCl2 (30 days, 0.5 mg kg-1) would have an additive effect on atherosclerosis risk factors. In the human study, we evaluated blood cells from 60 fishermen and 65 matched controls, where higher blood Hg levels, decreased erythrocyte functionality, structural alteration in hemoglobin, and compromised redox system in fishermen were observed. Furthermore, in fishermen, lymphocytes showed an exacerbated production of reactive oxygen species (ROS). As for the study with LDLr-/- animals treated with HgCl2, they presented decreased erythrocyte functionality; alteration in white blood cell count, increased macrophage phagocytic activity, elevation of plasma cytokines, accumulation of Hg in different organs, as well as alteration in renal and hepatic function. In isolated liver mitochondria, there was impairment of respiration and integrity of such organelle, as well as an increase in H2O2 generation. Therefore, our results show that, regardless of the model used, Hg contamination leads to systemic oxidative damage that can compromise organism health.