Biomarkers of Methylmercury Exposure Immunotoxicity among Fish Consumers in Amazonian Brazil

Abstract

Background: Mercury (Hg) is a ubiquitous environmental contaminant with neurodevelopmental and immune system effects. An informative biomarker of Hg-induced immunotoxicity could aid studies on the potential contribution to immune-related health effects.Objectives: Our objectives were to test the hypothesis that methylmercury (MeHg) exposures affect levels of serum biomarkers and to examine interactions between Hg and selenium (Se) in terms of these responses.Methods: This cross-sectional epidemiological study assessed adults living along the Tapajós River, a system long affected by MeHg. We measured antinuclear (ANA) and antinucleolar (ANoA) autoantibody levels and eight cytokines in serum samples (n = 232). Total Hg (including MeHg) and Se were measured in blood, plasma, hair, and urine.Results: The median (range) total Hg concentrations were 14.1 μg/g (1.1–62.4), 53.5 μg/L (4.3–288.9), 8.8 μg/L (0.2–40), and 3.0 μg/L (0.2–16.1) for hair, blood, plasma, and urine, respectively. Elevated titers of ANA (but not ANoA) were positively associated with MeHg exposure (log-transformed, for blood and plasma), unadjusted [odds ratio (OR) = 2.6; 95% confidence interval (CI): 1.1, 6.2] and adjusted for sex and age (OR = 2.9; 95% CI: 1.1, 7.5). Proinflammatory [interleukin (IL)-6 and interferon (IFN)-©], anti-inflammatory (IL-4), and IL-17 cytokine levels were increased with MeHg exposure; however, in the subset of the population with elevated ANA, proinflammatory IL-1®, IL-6, IFN-©, and tumor necrosis factor (TNF)-〈 and anti-inflammatory (IL-4) cytokine levels were decreased with MeHg exposure. Although Se status was associated with MeHg level (correlation coefficient = 0.86; 95% CI: 0.29, 1.43), Se status was not associated with any changes in ANA and did not modify associations between Hg and ANA titers.Conclusions: MeHg exposure was associated with an increased ANA and changes in serum cytokine profile. Moreover, alterations in serum cytokine profiles differed based on ANA response, suggesting a specific phenotype of MeHg susceptibility. Further research on the potential health implications of these observed immunological changes is warranted.

Alteration of Th1/Th2/Th17 cytokine profile and humoral immune responses associated with chromate exposure

“…IL-2, TNF-α and IFN-γ are all Th1 type cytokines, while IFN-γ, a pro-inflammatory cytokine, can help target cells generate various chemotactic factors to relieve the inflammatory response 27 28. TNF-α is a pleiotropic cytokine critical for inflammation, lymphoid neogenesis, and host defence against various pathogens, and plays multiple roles in the induction of cytokines IL-1, IL-6 and IL-8, and the activation of macrophages and neutrophils.…”

Environmental Influences on Systemic Lupus Erythematosus Expression

“…Metals such as mercury have been associated with antinuclear antibody and inflammatory cytokine production in some exposed individuals. 52 The one published study to date of occupational and avocational metal exposures in SLE cases compared to controls found that exposure to mercury in the occupational setting at least once per week was associated with a modestly (but not significantly) higher risk of SLE (OR 3.1; 95% CI 0.8 – 12.7). 28 Exposure to five or more days of stained or leaded glass as a hobby was also more common among SLE cases than controls, but the rarity of these exposures led to an imprecise effect estimate (OR 3.0; 95% CI 0.8 – 11.6).…”

Mercury health risk assessment among a young adult Lebanese population

“…MeHg is readily taken up by fish through trophic webs, consequently bioaccumulating and biomagnifying into the top predating fish, in addition to fisheating birds, and wild mammals (Gochfeld 2003). This makes fish consumption the primary source of Hg exposure in the general population (Nyland et al 2011;Schaefer et al 2014). In New Jersey, USA, one third of the sampled saltwater fish species were found to have concentrations of Hg above 0.5 ppm, which pose a human health risk for consumers (Burger and Gochfeld 2011).…”