Methylmercury and long chain polyunsaturated fatty acids are associated with immune dysregulation in young adults from the Seychelles child development study

• Published in: Environmental research 2020-04, Vol.183, p.109072-109072, Article 109072
• Main Authors: McSorley, Emeir M., van Wijngaarden, Edwin, Yeates, Alison J., Spence, Toni, Mulhern, Maria S., Harrington, Donald, Thurston, Sally W., Love, Tanzy, Jusko, Todd A., Allsopp, Philip J., Conway, Marie C., Davidson, Philip W., Myers, Gary J., Watson, Gene E., Shamlaye, Conrad F., Strain, J.J.
• Format: Article
• Language: English
• Subjects: Animals; Autoantibody; Autoimmune Diseases - etiology; Autoimmunity; Child; Cytokine; Diet; Fatty Acids, Omega-3; Fatty Acids, Unsaturated; Female; Humans; Immunoglobulin; Male; Methylmercury; Methylmercury Compounds - toxicity; Pregnancy; Seychelles; Young Adult
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2019.109072

Exposure to the environmental toxicant mercury (Hg) has been associated with immune dysregulation, including autoimmune disease, but few human studies have examined methylmercury (MeHg) exposure from fish consumption. We examined associations between MeHg exposure and biological markers of autoimmunity and inflammation while adjusting for long chain polyunsaturated fatty acids (LCPUFA). At age 19 years, hair total Hg (Y19Hg), LCPUFA status, a panel of 13 antinuclear antibodies (ANA), total serum immunoglobulins (Ig) IgG, IgA, and IgM and serum markers of inflammation (IL-1, IL-2, IL-6, IL-10, C-reactive protein (CRP), IFN-γ, TNF-α) were measured in the Seychelles Child Development Study (SCDS) Main Cohort (n = 497). Multivariable regression models investigated the association between Y19Hg and biomarkers, adjusting for prenatal total hair Hg (MatHg) and other relevant covariates, and with and without adjustment for LCPUFA. With each 1 ppm increase in Y19Hg (mean 10.23 (SD 6.02) ppm) we observed a 4% increased odds in a positive Combined ANA following adjustment for the n6:n3 LCPUFA ratio (β = 0.036, 95%; CI: 0.001, 0.073). IgM was negatively associated with Y19Hg (β = −0.016, 95%CI: 0.016, −0.002) in models adjusted for n-3, n-6 LCPUFA and when separately adjusted for the n-6:n-3 LCPUFA ratio. No associations were observed with MatHg. Total n-3 LCPUFA status was associated with reduced odds of a positive anti-ribonuclear protein (RNP) A. The n-3 LCPUFA were negatively associated with IL-6, IL-10, CRP, IFN-γ, TNF-α and positively with TNF-α:IL-10. There were positive associations between the n-6:n-3 ratio and IL-6, IL-10, CRP, IFN-γ, TNF-α and a negative association with TNF-α:IL-10. The Y19Hg exposure was associated with higher ANA and lower IgM albeit only following adjustment for the n-3 LCPUFA or the n-6:n-3 LCPUFA ratio. The clinical significance of these findings is unclear, but warrant follow up at an older age to determine any relationship to the onset of autoimmune disease. •Concurrent MeHg is associated with being positive for ANA and lower IgM but only following adjustment of n-3LCPUFA.•Prenatal methylmercury exposure was not associated with ANA or any biomarker of inflammation at age 19 years.•N-3 LCPUFA were associated with lower markers of inflammation.•Research is required to determine if MeHg exposure at an older age is associated with the onset of autoimmune disease.