Fig. 4
Lactate produced by glycolytic MSCs mediates their enhanced immunosuppressive effect. A Experimental design using MSCs pretreated or not with oligomycin alone (MSCOLN) or together with galloflavin (MSCOLN+GF) or siRNA against LDHA (MSCOLN+siLDHA). B Colorimetric analysis of MSC lactate efflux after 24 h of treatment. C–F Naive CD4+ T cells isolated from spleen of C57BL/6 mice were labeled with CTV and induced to differentiation into Th1 (C, D or Th17 (E, F) cells and were cultured alone (dark and light red bars, respectively) or together with MSCCTL (gray bars), MSCOLN (striped, gray bars), MSCOLN+GF (striped orange bars), or MSCOLN+siLDHA (striped yellow bars). After three days of co-culture, proliferation (C, E) and phenotype (D, F) of lymphocytes were characterized by flow cytometry. Results represent the mean ± SD of three independent experiments for lactate measurement in MSCs and three independent experiments with at least four different biological samples for CD4+ T cells; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 (unpaired Kruskal–Wallis test). Unless otherwise indicated, comparisons were with MSCs in basal or control conditions or with Th1 or Th17 cells