Figure 5.

Intracellular mycobacterial killing is improved by rifampicin-loaded liposomes with no cytotoxicity effect. dTHP-1 (5 × 10⁵ cells/mL) were infected with M. abscessus (MOI 10) for 3 h and the extracellular bacilli were killed with 250 µg/mL Amikacin for 1 h. (A) Cells were treated for 18 h with RIF-loaded liposomes (RIF–Lipo) and free drug (RIF) at different concentrations and bacterial growth was quantified by CFU assay. Results are shown as mean ± standard deviation (SD) of CFU values obtained from triplicate cultures and are representative of three independent experiments. (B) Cells were treated with unloaded liposomes (Lipo Empty), 96 µM rifampicin-loaded liposomes (RIF–Lipo) and 96 µM free drug (RIF) for 18 h, and bacterial growth was assessed by CFU assay. Results are shown as mean ± SD of CFU values obtained from triplicate cultures and are representative of three independent experiments. * p < 0.05, ** p < 0.01 and *** p < 0.0001 by two sided Student’s t-test. (C) Liposome formulations and rifampicin do not exert cytotoxicity on macrophages. dTHP-1 (2 × 10⁵ cells/200 µL) were stimulated with unloaded liposomes (Lipo Empty), 96 µM rifampicin-loaded liposome (RIF–Lipo) and 96 µM free rifampicin (RIF) for 18 h and then were subjected to MTT Assay. Cells were treated with 0.1% saponin at 37 °C for 30 min as negative control (Sap). Results are shown as mean ± standard deviation (SD) of OD_540nm values performed in triplicate and are representative of three independent experiments.