Preparation, Antituberculosis Function and Mechanism of Macrophage- Targeted circTRAPPC6B and Rifampicin Exosome Delivery System

Objective: To construct a composite exosome delivery system with macrophage-targeting ability, combining circular RNA circTRAPPC6B and the antituberculosis drug rifampicin (RIF) for the efficient treatment of pulmonary tuberculosis. The aim is to enhance the enrichment efficiency of drugs in infected macrophages and strengthen the clearance of intracellular Mycobacterium tuberculosis (MTB) by regulating the host immune response. Methods: Exosomes (Exo) were extracted from human dendritic cells by ultra-centrifugation. circTRAPPC6B was encapsulated into exosomes by electroporation. Rifampicin was embedded into the lipid bilayer of exosomes by hydrophobic insertion to obtain the RIF@Exo-circTRAPPC6B composite system. Subsequently, the surface of exosomes was modified with mannose to construct the M-Exo-circTRAPPC6B-RIF targeted delivery system. Transmission electron microscopy (TEM), nanoparticle size analyzer and Western blot were used to characterize the morphology, particle size, Zeta potential and marker proteins of exosomes. In vitro experiments used the J774A.1 macrophage model infected with H37Rv to evaluate the cell uptake rate, minimum inhibitory concentration (MIC) and the expression level of autophagy-related protein LC3-II/I of the delivery system. Results: The M-Exo-circTRAPPC6B-RIF delivery system with good stability and targeting was successfully constructed. This system significantly enhanced the uptake of drug-loaded exosomes by macrophages, effectively inhibited the proliferation of intracellular MTB, and activated the cell autophagy pathway. Conclusion: The mannose-modified exosome co-delivery system developed in this study can achieve the synergistic effect of circTRAPPC6B and rifampicin. While improving drug targeting, it also regulates the host immune response, providing a new strategy for the precise treatment of pulmonary tuberculosis.