Polyvinylidene fluoride alters inflammatory responses by activation-induced cell death in macrophages

Carbon nanotubes (CNTs) are nanomaterials that have been employed in generating diverse materials. We previously reported that CNTs induce cell death in macrophages, possibly via asbestosis. Therefore, we generated CNT-attached polyvinylidene fluoride (PVDF), which is an established polymer in membrane technology, and then examined whether CNT-attached PVDF is immunologically safe for medical purposes compared to CNT alone. To test this, we treated RAW 264.7 murine macrophages (RAW cells) with CNT-attached PVDF and analyzed the production of nitric oxide (NO), a potent proinflammatory mediator, in these cells. RAW cells treated with CNT-attached PVDF showed reduced NO production in response to lipopolysaccharide. However, the same treatment also decreased the cell number suggesting that this treatment can alter the homeostasis of RAW cells. Although cell cycle of RAW cells was increased by PVDF treatment with or without CNTs, apoptosis was enhanced in these cells. Taken together, these results indicate that PVDF with or without CNTs modulates inflammatory responses possibly due to activation-induced cell death in macrophages.