A Novel Thiocationic Liposomal Formulation of Antisense Oligonucleotides with Activity Against Mycobacterium tuberculosis

Abstract

This study describes the development of a novel thiocationic (OBEHYTOP) lipid-based formulation of phosphorothioate antisense oligonucleotides (PAOs) showing inhibitory activity against mycobacterium tuberculosis (mTB) as measured by an in vitro BACTEC 460TB assay. PAOs were designed based on sequences complementary to essential regions of the mycobacterial genome from published nucleic acid databases in GenBank. These included the superoxide dismutase sod A gene (TBS3), catalase-peroxidase katG gene (TBK1, TBK10), RNA polymerase beta-subunit rpo B gene (TBR5) and diaminopimelate decarboxylase lys A gene (TBL5). The effect of PAOs (TBS3, K1, K10, R5 and L5) alone on mTB was not significant compared with the no-drug control over a period of exposure of 150 h (ranges of −11.8 to +23.58% at 72 h; 15.26 to +25.82% at 96 h and −5.51 to +24.00% at 150 h). Liposomal formulations (10:5:2 OBEHYTOP:oleic acid:vitamin D₃) of PAOs resulted in statistically significant (p<0.05 in all cases) inhibition (ranges of −51.45 to −63.00% at 72 h; −56.75 to −67.96% at 96 h; −51.45 to −60.26% at 150 h) compared with PAOs alone, thiocationic liposomal control and liposomal components. Positive controls of streptomycin and isoniazid used at their minimum inhibitory concentrations of 2.00 and 0.10 μM, respectively, resulted in average % inhibition values of −94% and −97.36%, respectively, indicating that these thiocationic lipid-formulated PAOs showed inhibitory activity directed against mTB in vitro.