Fig. 1
Mechanical load-induced M1 macrophage polarization during tooth movement depends on H2S production. a Schematic illustration. b Representative images and semiquantification analysis of the tooth movement distance in mice. Mechanical load increased the tooth movement distance, and this result was partially reversed by HA injection and enhanced by GYY4137 injection. N = 5–6. ***P < 0.001 versus control; ###P < 0.001 versus force; &&&P < 0.001 versus force + HA. 1st M, the first molar; 2nd M, the second molar. Black arrow represents the direction of mechanical force. Blue triangles represent the tooth movement distance. Scale bar: 500 μm. c Representative immunohistochemical images and semiquantification analysis of cystathionine-β-synthase (CBS) expression on the compression side of distal roots. Large boxed areas show high-magnification views of the small boxed areas. N = 5–6. ***P < 0.001 versus control; ###P < 0.001 versus force. &&&P < 0.001 versus force + HA. Scale bar: 100 μm. d Representative immunofluorescence images and the corresponding hematoxylin–eosin (HE) staining of the compression side of distal roots and semiquantification of positive cells. The changes in CD68- (green) and inducible nitric oxide synthase (iNOS)-positive (red) M1 macrophage polarization (merged yellow) and CD68- (green) and CD163-positive (red) M2 macrophage polarization (merged yellow) are presented. Dashed lines mark the root outline. Arrow represents the direction of mechanical force. Large boxed areas show high-magnification views of the small boxed areas. Scale bar: 50 μm. N = 5–6; the positive staining cells were counted on five different slides from each sample. The final result came from the average of three tests. **P < 0.01, ***P < 0.001 versus control. ###P < 0.001 versus force. &&&P < 0.001 versus force + HA