Methylmercury causes glial IL-6 release

Methylmercury (MeHg) is an environmental toxin that causes severe neurological complications in humans and experimental animals. MeHg caused IL-6 release from the rat C6 glioma cells, the human U251HF glioma cells and the human retina pigment epithelial (ARPE-19) cells. These results plus those we reported earlier using mouse N9 microglia cells indicate that IL-6 induction may be a general property of MeHg among various glial cell types across species. MeHg caused a concentration-dependent increase of cellular oxidation with a maximal level reached by ∼10 μM MeHg, which was similar to that caused by 30 μM H2O2 or t-butyl hydroperoxide (tBH). The ability of MeHg to induce IL-6 release was not affected by exogenously added H2O2 or t-butyl hydroperoxide. Furthermore, IL-6 release was not accompanied by other cytokine release. Given the reports by others that IL-6 could modulate neuronal survival, glia may affect MeHg neurotoxicity by their IL-6 release when exposed to this neurotoxin.