Fig. 8

Chronic psychological stress mobilizes spleen-derived MDSCs into the lung in a CXCR2-dependent manner. A Representative pictures and growth curves of tumors in CXCR2^WT and CXCR2^KO mice under CUMS (n = 6). B The fluorescence intensity of lung metastases in CXCR2^WT and CXCR2^KO mice under CUMS (n = 3). C Representative lung images in HE staining for 2–4 weeks in CXCR2^WT and CXCR2^KO mice bearing breast cancer under CUMS (black circle indicates the metastatic lesions of the lung) (n = 3). D Representative immunofluorescence images for PMN formation for 2–4 weeks in the lungs of CXCR2^WT and CXCR2^KO mice bearing breast cancer under CUMS (CK19 labeled cancer cells, Gr-1 and CD11b labeled MDSCs, the scale bars indicate 10 μm). E MDSCs population in the lung, peripheral blood, and spleen of CXCR2^WT and CXCR2^KO mice bearing breast cancer under CUMS. F Flow diagram for establishing CXCR2^WT/KO bone marrow chimeric mice and follow-up detection. CXCR2^WT/WT mice that underwent sham surgical operation served as control (upper panel). Representative immunofluorescence images for the recruitment of exogenous mCherry-labeled MDSCs to the lung and PMN formation in the lung (lower panel). G Flow diagram for establishing CXCR2^KO/WT bone marrow chimeric mice and follow-up detection. CXCR2^KO/KO mice that underwent sham surgical operation served as control (upper panel). Representative immunofluorescence images for the recruitment of exogenous mCherry-labeled MDSCs to the lung and PMN formation in the lung (lower panel). Data are represented as Mean ± SD. For statistical analysis, repeated measures analysis of variance (A) and unpaired t-tests (E) were applied. ^*P < 0.05, ^#P < 0.01