University of Nebraska Medical Center (UNMC),Nebraska.
Title: Autophagy facilitates long acting antiretroviral drug depots and controlled drug delivery
Dr. Santhi Gorantla is an Associate Professor at University of Nebraska Medical Center (UNMC) in Omaha. Her research career in HIV started with her first postdoctoral fellowship on “Gene therapy strategies for HIV-1 in SCID-hu mouse model” in 1997. She developed a novel “Humanized mouse model for NeuroAIDS” with established human immune system, where chronic progressive HIV infection results in immune- and central nervous system pathologies. She recently procured a NIH R24 Resource-Related Grant to establish a Center for Humanized Mice and support researchers across US with their research using humanized mouse models. She has established several collaborative projects with investigators at UNMC and also from other institutes in US. Using humanized mouse model we are currently working on understanding CNS viral reservoirs and their behavior with drugs of abuse. We are also developing new therapeutic strategies for effective delivery of anti-retroviral drugs to target the viral reservoirs.
URMC-099, a MLK-3 inhibitor, induces autophagy in human monocyte-derived macrophages (MDM), which in turn lead to sequestration of nanoformulated antiretroviral drugs from endosomes and multi-vesicular bodies into autophagosomes. This resulted in drug retention and enhanced antiretroviral efficacy. Mice when injected with nanoformulated modified dolutegravir (NMDTG) and URMC-099, showed increased drug in lymph nodes, spleen and liver compared to NMDTG treatment alone. Plasma drug concentrations were high (~450 ng/ml) up to day 42 after parenteral injection. Since autophagy is linked to exosome biogenesis and the exosomes have their natural ability to reach different lymphoid organs, we hypothesized that modulating cellular autophagy can lead to drug loaded exosomes. These can speed drug delivery to HIV lymphatic reseroivrs. To test this idea, we treated MDM with nanoformulated atazanavir (nanoATV) and showed significant drug loading into exosomes. MDMs produced drug loaded exosomes for 14 days with enhanced drug concentration following URMC-099 treatment. URMC-099 enabled the long term presence of nanoATV into autophagosomes where drug loading was facilitated in exosomes. We reasoned that 30-150 nm sized extracellular vesicles can readily enter the lymphatic system. As exosomes also transport microRNA, peptides and small molecules between cells, we posit that modulating autophagy can be exploited as novel controlled drug delivery system to target lymphoid organs as well as to cross blood brain barrier. Such a delivery system could be used to target these tissue compartments recognized as HIV reservoirs. We conclude that harnessing autophagy, a tightly regulated and evolutionarily conserved lysosomal degradation process that controls cellular homeostasis by recycling cytoplasmic protein aggregates, damaged organelles, lipid droplets and intracellular pathogens can facilitate antiretroviral drug delivery.