Transient transfection of the respiratory epithelium with gamma interferon for host-directed therapy in pulmonary tuberculosis

Bharti, Reena; Srivastava, Ashish; Roy, Trisha; Verma, Khushboo; Reddy, DV Siva; Shafi, Hasham; Verma, Sonia; Raman, Sunil K.; Singh, Amit K.; Singh, Jyotsna; Ray, Lipika; Misra, Amit

Nebulized gamma interferon (IFN-γ) protein has been studied for clinical safety and efficacy against pulmonary tuberculosis (TB). The protein is expensive, requires a cold chain, and is difficult to deploy in limited-resource, high-incidence settings. We generated preclinical proof of concept (PoC) for a dry powder inhalation (DPI) containing DNA constructs to transiently transfect the lung and airway epithelium of mice with murine IFN-γ. Bacterial colony forming units (CFU) in the lungs of mice infected with Mycobacterium tuberculosis (Mtb) reduced from about 106/g of tissue to ∼104 after four doses given once a week. Nodular inflammatory lesions in the lungs reduced significantly in number. Immunohistochemistry of infected lung sections for LC3-1 and LAMP-1 indicated autophagy induction between 18-48h after inhalation. ELISA on bronchioalveolar lavage (BAL) fluid showed differences in kinetics of IFN-γ concentrations in the epithelial lining fluid of healthy versus infected mice. Uninfected mice receiving DNA constructs expressing a fluorescent protein were live-imaged. The fluorescence signals from the intracellular protein peaked at about 36h after inhalation and declined by 48h. These results establish preclinical PoC of the efficacy of a DPI and dosing regimen as host-directed and transient gene therapy of experimental pulmonary TB in mice, justifying preclinical development.