An immunoregulator nanomedicine approach for the treatment of tuberculosis

Introduction: A nanoparticle composed of a poly (lactic-co-glycolic acid) (PLGA) core and a chitosan (CS) shell with surface-adsorbed 1,3 β-glucan (β-glucan) was synthesized. The exposure response of CS-PLGA nanoparticles (0.1 mg/mL) with surface-bound β-glucan at 0, 5, 10, 15, 20, or 25 ng or free β-glucan at 5, 10, 15, 20, or 25 ng/mL in macrophage in vitro and in vivo was investigated. Results: In vitro studies demonstrate that gene expression for IL-1β, IL-6, and TNFα increased at 10 and 15 ng surface-bound β-glucan on CS-PLGA nanoparticles (0.1 mg/mL) and at 20 and 25 ng/mL of free β-glucan both at 24 h and 48 h. Secretion of TNFα protein and ROS production increased at 5, 10, 15, and 20 ng surface-bound β-glucan on CS-PLGA nanoparticles and at 20 and 25 ng/mL of free β-glucan at 24 h. Laminarin, a Dectin-1 antagonist, prevented the increase in cytokine gene expression induced by CS-PLGA nanoparticles with surface-bound β-glucan at 10 and 15 ng, indicating a Dectin-1 receptor mechanism. Efficacy studies showed a significant reduction in intracellular accumulation of mycobacterium tuberculosis (Mtb) in monocyte-derived macrophages (MDM) incubated with on CS-PLGA (0.1 mg/ml) nanoparticles with 5, 10, and 15 ng surface-bound β-glucan or with 10 and 15 ng/mL of free β-glucan. β-glucan-CS-PLGA nanoparticles inhibited intracellular Mtb growth more than free β-glucan alone supporting the role of β-glucan-CS-PLGA nanoparticles as stronger adjuvants than free β-glucan. In vivo studies demonstrate that oropharyngeal aspiration (OPA) of CS-PLGA nanoparticles with nanogram concentrations of surface-bound β-glucan or free β-glucan increased TNFα gene expression in alveolar macrophages and TNFα protein secretion in bronchoalveolar lavage supernatants. Discussion: Data also demonstrate no damage to the alveolar epithelium or changes in the murine sepsis score following exposure to β-glucan-CS-PLGA nanoparticles only, indicating safety and feasibility of this nanoparticle adjuvant platform to mice by OPA.