Effects of manganese dioxide on macrophages under different exposure schemes

Manganese dioxide is a material that is more and more used in its particular form, for many industrial applications such as chemical catalysis or for batteries. Thus, workers can be exposed to this particulate chemical. It is known that overexposure to manganese leads to a brain disease called manganism. However, manganese is also known to impact the pulmonary function, which is important as pulmonary exposure is of prime importance for workers. We thus investigated the effects of manganese dioxide on macrophages, i.e. the scavenger cells that take particulates in charge in our bodies. To this purpose, we used a combination of proteomic and targeted approaches, in order to obtain a wide view of the cellular responses to manganese dioxide. We also used a repeated exposure mode, in order to better mimic occupational exposure. Our results point out the fact that manganese oxide nanoparticles are rather toxic for macrophages and induce mitochondrial dysfunction, oxidative stress and a pro-inflammatory response. Environmental significanceManganese dioxide is more and more used in batteries, so that workers in batteries factories are exposed to this metallic oxide. As always for particulate materials, macrophages are the first line of defense of the organism. We thus investigated the effects of manganese dioxide on macrophages, using a repeated exposure scheme to mimic occupational exposure, and the effects were documented by a combination of proteomic and targeted approaches. The functional effects include mitochondrial dysfunction, oxidative stress and inflammation.