Lunar and Martian regolith simulants compromise airway barrier function and trigger inflammation

Little is known on the health risks for the astronauts exposed to space-derived materials such as regolith, the mixture of dust and rock particles covering the surfaces of Moon and Mars. We combine an in vitro model of exposure of human airway epithelial and peripheral blood mononuclear cells to regolith, with an in vivo murine exposure model, to assess the effects of Martian and Lunar regolith simulants. Exposure to both Moon or Mars regolith causes cellular cytotoxicity and induced strong proinflammatory responses in vitro. In mice, intranasal regolith exposure impairs epithelial barrier integrity in the airways, increases pro-fibrotic gene expression, immune cell recruitment, and elevates amounts of inflammatory proteins in bronchoalveolar lavage fluid. Lunar regolith simulant LMS-1 shows particularly strong barrier-damaging and inflammatory effects in differentiated bronchial epithelial cells and in the in vivo mouse model. These findings highlight regolith as an airway irritant driving inflammation and barrier dysfunction, underscoring the need for dust mitigation strategies to protect astronaut health during long-term space missions on Moon or Mars.