| Inflammation and airway destruction are hallmarks of many debilitating lung diseases such as chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), acute lung injury (ALI), and cancer. Gene-based therapeutic interventions that modulate this pathologic inflammatory response are likely to reduce the progressive destruction to lung airways. In this regard, a number of strategies have been evaluated for targeting the pulmonary vasculature; particularly those based on serotype 5 Adenovirus (Ad5). The advantages of Ad over other vector systems include: in vivo stability, low oncogenic potential, and large packaging capacity. Yet, specific and efficient gene delivery to the lung has been hampered by a number of barriers in vivo; mainly the degree by which Ad5 vectors are sequestered in the liver. The complexity of Ad5 liver tropism has largely been unraveled, permitting improved efficacy of Ad5 gene delivery. However, Kupffer cell (KC) scavenging and elimination of Ad5 still represent major obstacles to lung delivery strategies since KC uptake substantially reduces Ad5 bioavailability for target tissues and compensatory dose escalation leads to hepatotoxicity.;Efficient targeting of cell types within the lung may preclude the need for viral modifications that ablate liver sequestration mechanisms. Leukocytes represent an ideal target for delivery of therapeutics to the pulmonary vasculature as venous blood flow is first directed through the pulmonary vasculature, and circulating leukocytes accumulate within the lung due to reduced transit rates through the extensive microvasculature network. The contributing role of leukocytes in the pathogenesis of lung diseases, further highlights this population as an ideal target for therapeutic intervention of inflammatory lung disease.;Given the size and location of the lung leukocyte pool, we designed a novel lung-targeting approach based on modulation of Ad5 vector tropism to myeloid leukocytes. We demonstrate that this leukocyte-targeting approach specifically localizes Ad5 virions and gene transfer to the lung microvasculature and prevents KC uptake and hepatocyte transduction. This strategy resulted in a 165,000-fold enhanced lung-targeting, compared to unmodified Ad5. This work demonstrates that this novel myeloid-targeting approach, for the first time, results in significantly enhanced lung gene transfer and elimination of liver tropism in the absence of further capsid modifications.;Keywords: Adenovirus, Inflammation, Kupffer cells, Lung, Myeloid, Targeting. |
