Macrophage polarization by plasma sprayed ceria coatings on titanium-based implants: cerium valence state matters

•Ceria coatings exhibited a valence-dependent modulation of macrophage polarization.•The B-IV coating possessed higher CAT-like activity but lower POD-like activity.•The B-IV coating (high Ce4+/Ce3+ ratio) induced a M2-type macrophage response.•The B-IV coating suppressed the ROS-dependent NF-κB activation.