Investigating The Intracellular Bactericidal Effects Of Rifampicin Loaded S-Protected Thiomeric Chitosan Nanocargoes Against Mycobacterium Tuberculosis

The antibiotic drug resistance in Mycobacterium tuberculosis (M.tb) is typically associated with immune evasion shared by pathogenic bacterium and intrinsic antimycobacterial drug resistance. These factors significantly contribute to the limited delivery of drugs intracelullary thereby posing an ever-growing threat to mankind. A promising approach to tackle this multi-drug resistance is to use nanocargoes (NCs) based drug delivery approach. The aim of the present study was to develop mannose coated S-protected thiomeric site-specific nanocargoes (MPTCh-NCs) of Rifampicin (Rif) in order to deliver drug locally inside the macrophages. This NCs-based delivery system modifies the macrophage activation states via mannose receptors and endocytosis to alter the macrophage activation state thus providing synergistic antimycobacterial effects. MPTCh-NCs were synthesized by ionic gelation method and assessed for particle size and encapsulation efficiency Moreover, MPTCh-NCs were also investigated in in vitro for drug release, macrophage uptake, buffering potential, Mycothione reductase (MTR) inhibition ability, minimum inhibitory concentration (MIC), phagolysosomal fusion, reactive oxygen species (ROS) production apoptosis and RV 1258 inhibition. The in vivo bioavailability study of MPTCh-NCs was also evaluated in male BALB/c models over a period of 72 h. The optimized MPTCh-NC formulation was nanosized (390 +/- 20 nm) with better EE of Rif i.e. 73.68 +/- 5.99%. The MPTCh-NCs showed better buffering capacity at different pH ranges, 35.69 folds higher macrophage uptake than Rif with P-gp inhibition potential and pronounced MTR inhibition potential. The MPTCh-NCs exhibited MIC of 16 mu g/ml by drug susceptibility testing. Flow cytometric analysis of MPTCh-NCs exhibited, increased apoptosis (33.29%). Real time PCR data suggested enhanced RV 1258 inhibition potential (0.387 fold expression) of the MPTCh-NCs. In vivo results indicated increased bioavailability of MPTCh-NCs (AUC 12.31 folds higher) in comparison to conventional drug Rif. In summary, the observed capacity of the mannose coated S-protected NCs-based approach to deliver therapeutic levels of Rif selectively has potential to improve the therapeutic management against drug resistant tuberculosis.