Intramacrophage Mycobacterium tuberculosis efflux pump gene regulation after rifampicin and verapamil exposure
Journal of Antimicrobial Chemotherapy
Objectives: Since resistance of Mycobacterium tuberculosis (Mtb) partially derives from efflux pumps (EPs) in the plasma membrane, the current study evaluates EPs in Mtb exposed to rifampicin in the presence of the EP inhibitor verapamil, within a macrophage environment. Methods: Human acute monocytic leukaemia cell line THP-1 was infected with Mtb H 37 Rv and exposed to rifampicin and verapamil alone and in combination for 24 and 72 h. After RNA extraction, quantitative PCR was carried out for
... was carried out for 11 EP genes using SYBR green PCR master mix in the StepOne TM Real-Time PCR System. Results: After 24 h of exposure to rifampicin, Mtb H 37 Rv showed that 10 EP genes were up-regulated when compared with the control. The rifampicin/verapamil combination induced down-regulation of 54.5% (6/11) of the EP genes. At 72 h, rifampicin exposure induced up-regulation of 10 EP genes and rifampicin/verapamil induced down-regulation of 8 EP genes, which suggests effective EP-inhibitory activity of verapamil against Mtb H 37 Rv in an intramacrophage environment. Conclusions: The current study demonstrated that rifampicin/verapamil caused down-regulation of several EP genes in Mtb inside the macrophage environment. In vivo trials may show that rifampicin/verapamil therapy could be of value in enhancing anti-TB treatment.