Increase in antibiotic resistance is a global concern worldwide, with 480,000 new cases of multi-drug resistant tuberculosis (MDR-TB) diagnosed each year. Therefore, the goals for the Nanotherapeutics for Antibiotic Resistant Emmerging Bacterial pathogens (NAREB) research cluster, are the design of novel nanotherapeutics to overcome the antibiotic resistance issues, including MDR-TB, through the enhanced delivery and effect of approved and emerging antibacterial compounds. Bedaquiline (BQ) is the first new drug for the treatment of MDR-TB in 50 years and was recently FDA-approved in 2012. However, its high toxicity and its poor water solubility still hamper its therapeutic action. Considering this, bedaquiline is an excellent candidate for improvement by encapsulation into biocompatible nanoparticles for enhanced delivery into the infected tissues.  In this study, we have shown that bedaquiline was very well encapsulated in lipid nanoparticles (LNP), with an encapsulation yield superior to 90%, with payloads up to 10% (w/w) and was possible to freeze-dry the formulations and retain nanoparticle stability. Following formulation of neutral and cationic BQ-LNPs, both were compared for their physico-chemical as well as biological features.  The cytotoxicity of the BQ-LNPs indicated that particles were well tolerated at desired doses as no cytotoxic effect on A549, HepG2 and THP-1 cell lines of bedaquiline-loaded nanocarriers was observed at the concentration needed to kill the bacteria. Furthermore, blood testing also proved that LNP carriers are very well tolerated without any significant haemolysis, platelets activation, coagulation or complement activation. Testing with TB strains demonstrated that the bedaquiline was highly active when encapsulated, compared to the free drug, with identical MIC values against TB strain H37Rv. BQ-LNPs were also tested in TB-infected human macrophages in vitro, indicating that cationic BQ-LNPs were more rapidly internalized than neutral particles. However, bio-distribution in TB-infected mice found that neutral LNPs were more able to enter inflamed tissues in infected lungs. The effect of active tri-mannose targeting against macrophages was also studied with TB-infected mice but found no significant changes in efficacy under the test conditions used. Bacterial burden determination after 13 days of infection of C3HeB/FeJ mice infected by TB strain H37Rv confirmed that neutral LNPs, able to decrease bacterial burden with more efficacy than free drug, were the most promising candidate as novel nanotherapeutics to improve actual treatments. In conclusion, this work enabled us to demonstrate that nanoencapsulation of bedaquiline in lipid nanocarrier is a very promising way to improve bedaquiline-based treatments of M. tuberculosis infections. Up to now, we could manage to identify the best LNP carrier among 4 types, with different surface charges and with or without active targeting against macrophages, which appear very promising due to its capacity to enter inflamed tissues. Further studies would imply to better characterize whether this new bedaquiline formulation can decrease adverse effects, like cardiac ones thanks to a lower accumulation in heart when the drug is delivered after nanoencapsulation. The other perspective is to test this new nanotherapeutics against resistant strains both in vitro and in vivo with the aim to improve treatment against MDR-TB. *Acknowledgement: This work is part of the NAREB European research network (Collaborative Project) supported by the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 604237.
Journal: TechConnect Briefs
Volume: 3, Biotech, Biomaterials and Biomedical: TechConnect Briefs 2018
Published: May 13, 2018
Pages: 59 - 62
Industry sector: Medical & Biotech
Topics: Biomaterials, Materials for Drug & Gene Delivery