The risk of developing TB is estimated to be between 26 to 31 times greater in people living with HIV-1. TB suppresses the macrophage anti-bacterial response by preventing the maturation of phagosomes to phagolysosomes (Ca2+ dependent) and suppressing the production of intracellular reactive oxygen species and reactive nitrogen species (ROS/RNS) and pro-inflammatory cytokines. Effective antibacterial drugs against Mycobacterium tuberculosis exist (e.g., rifampin, isoniazid). However, these drugs have a major challenge with respect to entering macrophage in order to eradicate the microbe. In addition, the low intracellular drug concentrations are rapidly cleared from macrophage before the microbe has been completely eradicated. These issues have clinical implications: 1) TB treatment is lengthy in order to eradicate the microbe within the cells (minimum 6 month-treatment); and 2) poor cellular drug penetration plays a role in the generation of drug resistant strains, due to the periods of sub-optimal drug exposure of the microbe, allowing the microbe to mutate and become resistant. Thus it is necessary to develop targeted macrophage therapies in which the effects of current TB drugs act synergistically with the actions of the innate immune system to eradicate pathogens. This strategy may potentially reduce the drug dosage required, shorten the duration of treatment, and reduce the emergence of drug resistance. We have developed a macrophage targeted nanoparticle drug delivery system that is combined with immunomodulation using a single ligand, ?-glucan. We designed a core-shell nanoparticle prepared from the biocompatible polymers, poly-lactic-co-glycolic acid (PLGA; core containing TB drug) and chitosan (CS; shell) with surface adsorbed ?-glucan (GLU) (GLU-CS-PLGA). GLU on the nanoparticle's surface binds to Dectin-1 on macrophage, enhancing cellular uptake. This binding also activates macrophage, enhancing the production of Ca2+, ROS/RNS and cytokines. We will first determine the in vitro cellular pharmacokinetics (PK) and pharmacodynamics (PD) of the GLU-CS-PLGA nanoparticles utilizing a novel PK/PD-based macrophage cell culture system. These data will inform our in vivo mouse studies. We will next determine the PK and PD of the GLU-CS-PLGA nanoparticles in vivo in a healthy mouse model. These studies will yield the optimal dose, route of delivery, biodistribution, PK and PD of the nanoparticle. Physiologically based PK (PBPK) modeling will next be used to integrate the in vitro and in vivo data to provide key insights for future in vivo TB studies. This research represents a paradigm shift whereby nanocarrier systems may be designed based on first principles with in silico and in vitro model predictions. This approach will broaden our scientific knowledge of TB disease therapies and, by combining targeted drug delivery with immune augmentation, create new approaches that will facilitate reducing individual drug doses, shorten drug duration, reduce systemic drug toxicity and reduce the development of drug resistance.
The goal of this proposal is to use novel nanoparticle formulations that target TB drugs to specific cells of the immune system called macrophages while also activating these cells. If successful, this combination of multidrug therapy together with immunotherapy will lead to better treatment outcomes compared to either approach alone.
