Carbon Nanomaterials Stimulate HMGB1 Release From Macrophages and Induce Cell Migration and Invasion.

Carbon nanomaterials (CNMs) are widely used in industrial and medical sectors. The increasing exposure of CNMs necessitates the studies of their potential environmental and health effects. High-mobility group box-1 (HMGB1) is a nuclear DNA-binding protein, but when released from cells, may cause sustained inflammatory response and promote cell migration and invasion. In this work, we found that 7-day exposure of 2.5 mg/kg/day CNMs, including C60, single-walled carbon nanotubes, and graphene oxides significantly elevated the level of HMGB1 in blood and lung lavage fluids in C57BL/6 mice. Subsequently, cellular effects and underlying mechanism were explored by using Raw264.7. The results showed that noncytotoxic CNMs enhanced HMGB1 intracellular translocation and release via activating P2X7 receptor. Released HMGB1 further activated receptor for advanced glycation endproducts (RAGE) and downstream signaling pathway by upregulating RAGE and Rac1 expression. Simultaneously, CNMs prepared the cells for migration and invasion by modulating MMP2 and TIMP2 gene expression as well as cytoskeleton reorganization. Intriguingly, released HMGB1 from macrophages promoted the migration of nearby lung cancer cell, which can be efficiently inhibited by neutralizing antibodies against HMGB1 and RAGE. Taken together, our work demonstrated that CNMs stimulated HMGB1 release and cell migration/invasion through P2X7R-HMGB1-RAGE pathway. The revealed mechanisms might facilitate a better understanding on the inflammatory property and subsequent cell functional alteration of CNMs.