Amelioration of emphysema in mice through lentiviral transduction of long-lived pulmonary alveolar macrophages
Andrew A. Wilson, … , Bela Suki, Darrell N. Kotton
Andrew A. Wilson, … , Bela Suki, Darrell N. Kotton
Published December 21, 2009
Citation Information: J Clin Invest. 2010;120(1):379-389. https://doi.org/10.1172/JCI36666.
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Technical Advance Genetics

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.

Authors

Andrew A. Wilson, George J. Murphy, Hiroshi Hamakawa, Letty W. Kwok, Sreedevi Srinivasan, Avi-Hai Hovav, Richard C. Mulligan, Salomon Amar, Bela Suki, Darrell N. Kotton

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Figure 6

Amelioration of elastase-induced emphysema in mice treated with EF1α-hAAT lentivirus.

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Amelioration of elastase-induced emphysema in mice treated with EF1α-hAA...
(A–D) Analysis of BAL cells and BAL fluid (BALF) from mice treated with EF1α-GFP versus EF1α-hAAT lentiviral vectors followed by intratracheal elastase. (A) In mice treated with EF1α-GFP lentiviral vector, the percentage of AMs in the BAL that expressed GFP is shown for each time point after elastase exposure. (B) hAAT protein levels in the BAL fluid of EF1α-hAAT–treated mice following elastase exposure. (C and D) Kinetics of macrophage recruitment (C) and neutrophil recruitment (D) following elastase exposure. Data are represented as means ± SEM. (E) Representative hematoxylin and eosin–stained lung sections from the indicated groups 21 days after elastase exposure. Scale bars: 100 μm. (F–I) Comparison of lung compliance (C), equivalent alveolar diameter (Deq), heterogeneity (SD of Deq), and area-weighted mean alveolar diameter (D2), a parameter sensitive to changes in both airspace enlargement and its heterogeneity (28). (J) Structure-function relationship demonstrating that increases in D2 correlated with increases in C (r2=0.694). Note that there was no difference between the control groups of PBS-exposed mice treated with either GFP- or AAT-expressing vectors. The graph in J combines the data in F and I. Box plots in A, B, and F–I illustrate median (horizontal line), 25th and 75th percentiles (upper and lower box boundaries), and highest and lowest observed values (whiskers). *P < 0.05; **P < 0.01; ***P < 0.001 (ANOVA with post-hoc Tukey’s multiple comparisons test).