A novel model and molecular therapy for Z alpha-1 antitrypsin deficiency

Animal models that closely resemble human disease can present a challenge. Particularly so in alpha-1 antitrypsin deficiency (alpha(1)ATD), as the mouse alpha-1 antitrypsin (alpha(1)AT) cluster encodes five highly related genes compared with the one in humans. The mouse PI2 homologue is closest to the alpha(1)AT human gene. We have changed the equivalent mouse site that results in the Z variant in man (Glu342Lys) and made both the "M" and "Z" mouse PI2 alpha(1)AT proteins. We have tested the ability of a small-molecular-weight compound CG to alleviate polymerisation of these mouse alpha(1)AT proteins as it has been shown to reduce aggregates of Z alpha(1)AT in man. We found that (1) CG specifically reduces the formation of polymers of recombinant mouse "Z" protein but not "M" protein; (2) whereas there is significantly more alpha(1)AT secreted from Chinese Hamster Ovary cells transfected with the mouse "M" alpha(1)AT gene than with the "Z" (20.8 +/- A 3.9 and 6.7 +/- A 3.6, respectively; P < 0.005), CG increased the alpha(1)AT levels secreted from "Z" cells (21.2 +/- A 0.01) to that of "M" (20.2 +/- A 0.02). The data support the concept that the murine "Z" gene is a potential model for the study of alpha(1)ATD and that mice expressing this gene would be relevant for testing treatments in vivo.