Fig. 4

ESAT-6 inhibits TLR2 expression and phagocytosis of M. tb in THP-1 macrophage. A, B The effect of different concentrations of ESAT-6 alone on TLR2 protein levels in macrophages. THP-1(A) cells (1 × 10⁶) were co-incubated with different concentrations of ESAT-6 for 24 h, then total protein was extracted and TLR2 expression level was detected by WB. Densitometric quantification of representative blots were performed relative to β-actin levels. C, D ESAT-6 inhibits M. tb-induced expression of TLR2 in a dose-dependent manner. THP-1(A) cells (1 × 10⁶) were co-incubated with M. tb and different concentrations of ESAT-6 for 24 h. Densitometric quantification of representative blots were performed relative to β-actin levels. E, F The RFP-M. tb dose-dependent phagocytosis curve at four hours. G, H The RFP-M. tb time-dependent phagocytosis curve at MOI = 50. I THP-1(A) was co-incubated with different concentrations of ESAT-6 for 24 h followed by RFP-expressing H37Ra phagocytosis for 4 h. J Dose–response curves for EAST-6 inhibition of macrophage phagocytosis were examined by flow cytometry. Data are representative of at least three different experiments. Results are mean ± SEM. *p < 0.05, **p < 0.01 and ***p < 0.001