Amelioration of emphysema in mice through lentiviral transduction of long-lived pulmonary alveolar macrophages

Abstract

Directed gene transfer into specific cell lineages in vivo is an attractive approach for both modulating gene expression and correcting inherited mutations such as emphysema caused by human α1 antitrypsin (hAAT) deficiency. However, somatic tissues are mainly comprised of heterogeneous, differentiated cell lineages that can be short lived and difficult to specifically transfect. Here, we describe an intratracheally instilled lentiviral system able to deliver genes selectively to as many as 70% of alveolar macrophages (AMs) in the mouse lung. Following a single in vivo lentiviral transduction, genetically tagged AMs persisted in lung alveoli and expressed transferred genes for the lifetime of the adult mouse. A prolonged macrophage lifespan, rather than precursor cell proliferation, accounted for the surprisingly sustained presence of transduced AMs. We utilized this long-lived population to achieve localized secretion of therapeutic levels of hAAT protein in lung epithelial lining fluid. In an established mouse model of emphysema, lentivirally delivered hAAT ameliorated the progression of emphysema, as evidenced by attenuation of increased lung compliance and alveolar size. After 24 weeks of sustained gene expression, no humoral or cellular immune responses to hAAT protein were detected. Our results challenge the dogma that AMs are short lived and suggest that these differentiated cells may be a possible target cell population for in vivo gene therapy applications, including the sustained correction of hAAT deficiency.

Cycling to work in London and inhaled dose of black carbon

“…Secondly, in Malawian adults we found that AM carbon tracks closely with the BC-generating potential of the fuel regularly used in the home for cooking [30]. Thirdly, the lifespan of AM in the lower airway, and therefore its ability to acquire inhaled BC, is up to several months [31]. A further limitation is that there was a sex imbalance between cyclists and non-cyclists in the present study.…”

Highly compacted biodegradable DNA nanoparticles capable of overcoming the mucus barrier for inhaled lung gene therapy

“…In contrast, PBAE-CPs transfected only 3% of total cells, similar to previous findings with other leading nonviral (45-47) and viral (48,49) vectors. PBAE-MPPs demonstrated transgene expression in 12% of the CD45-negative nonimmune cells in the mouse lung, in contrast to the predominant transduction of immune cells achieved by viral vectors (50). Of note, the nonimmune cells in the lung lumen include airway epithelial cells, which comprise less than 1% of the total respiratory epithelial surfaces (51), as well as alveolar epithelial cells types I and II, which constitute 8% and 15% of the total peripheral lung cells, respectively (52,53).…”

Assessment of F/HN-Pseudotyped Lentivirus as a Clinically Relevant Vector for Lung Gene Therapy

“…At least two previous studies have shown that lentiviral vectormediated transduction of mouse lung leads to persistent (15 and 24 mo) gene expression in the murine lower airways (18,19). However, both studies used a VSV-G-pseudotyped lentiviral vector, which almost exclusively transduces alveolar macrophages, rather than lung epithelial cells.…”