Fig. 2: Lactate induces rapid BM neutrophil mobilization and recruitment.

a BM neutrophil frequency (numbers per 10⁶ acquired cells by flow cytometry) 4 h following i.p. lactate treatment in vivo (n = 6, PBS or 50.5 mg lactate; n = 5, 30 mg lactate).***p (PBS vs. 30 mg lactate) = 0.004. b, c Quantitative analysis and representative flow cytometry density plots for b PB neutrophils and c liver neutrophils frequency (n = 8, PBS or 50.5 mg lactate; n = 6, 30 mg lactate) following lactate injection.***p(PBS vs. 30 mg lactate in the PB) = 0.0008; **p(PBS vs. 30 mg lactate in the liver) = 0.0023; ***p(30 mg lactate vs. 50 mg lactate in the liver) = 0.0003. d Neutrophil frequency in PB at different time points following 50.5 mg lactate treatment (n = 5). e Representative TPLSM 3D images 4 h post PBS (left panel) or lactate (right panel) treatment, in calvarial bone of chimeric mice reconstituted with Ly6G tdTomato neutrophils (red). Sca-1 eGFP marked the endothelial cells (green) and second harmonic generation marked the bone (SHG; blue). White dashed lines indicate superior sagittal sinus (calvaria central sinus), arrows indicate BM, circulating or mobilized neutrophils. Representative images out of three independent experiments are shown. Scale bar, 50 μm. f Quantitative analysis for PB ROS^high neutrophils frequency following lactate administration (n = 6). g A schematic illustration of the protocol for LPS with LDHA or MCT4 inhibitors administration. h Frequency of PB neutrophils following LDHA inhibitors (n = 4, PBS + vehicle; n = 3, LPS + vehicle; n = 4, LPS with FX11; n = 5, two injections of PBS or LPS + PBS; n = 4, LPS with sodium oxamate). i Frequency of PB ROS^high neutrophils following LDHA inhibitors (n = 3, PBS + vehicle or LPS + vehicle; n = 5, LPS with FX11; or two injections of PBS; n = 4, LPS + PBS or LPS with sodium oxamate). j, k Frequency of  j PB neutrophils or k PB ROS^high neutrophils following MCT4 inhibitor (n = 4). j **p(PBS + vehicle vs. LPS + vehicle) = 0.0032; *p(LPS + vehicle vs. LPS + CHC) = 0.0163; k ***p(PBS + vehicle vs. LPS + vehicle) = 0.0006; **p(LPS + vehicle vs. LPS + CHC) = 0.0073. Data are represented as mean ± SEM from 3 to 5 independent experiments. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001, one-way ANOVA with Tukey’s post hoc test (a–c, h–k), two-way ANOVA with Bonferroni post hoc test (d) or Student’s two-tailed unpaired t test (f). See also Supplementary Fig. 2.