Hepatic α1-antitrypsin mRNA content in cirrhosis with normal and abnormal protease inhibitor phenotypes

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Abstract
We quantitated α1-antitrypsin mRNA in normal, α1-antitrypsin-deficient cirrhotic and biliary cirrhotic livers using two-dimensional electrophoretograms of [35 S] methionine-labeled translational products of total hepatic RNA and RNA/DNA hybridization. α1-antitrypsin precursor product was identified by immunoprecipitation. The relative abundance of α1-antitrypsin product from normal (0.989 ± 0.197), cirrhotic (0.956 ± 0.062) and α1-antitrypsin deficient (0.818 ± 0.12) livers was not significantly different. Although (RNA/DNA) was decreased in the PiZZ cirrhotic livers compared to normal (0.56 ± 0.045 vs. 0.95 ± 0.225), it equaled that found in the PiM cirrhotic livers (0.56 ± 0.055). The concentration of α1-antitrypsin mRNA [relative abundance × (RNA/DNA)], while decreased in PiZZ compared to normal liver, is thus no different in PiZZ cirrhotics than in PiM cirrhotics. We confirmed this observation by quantitation of the α1-antitrypsin mRNA using an α1-antitrypsin genomic probe. By RNA/DNA hybridization, α1-antitrypsin mRNA was equal in PiM cirrhotic and PiZZ cirrhotic (38.48 ± 4.5 vs. 31.93 ± 2.1), but significantly decreased from noncirrhotic PiM liver (58.36 ± 12.7). We conclude that α1-antitrypsin mRNA is decreased in cirrhosis of any etiology, and this decrease appears to represent a general response of the liver to injury. Since the decreased α1-antitrypsin mRNA in PiM cirrhotics is associated with normal serum α1-antitrypsin levels, it is unlikely that the decreased α1-antitrypsin mRNA in PiZZ cirrhotics accounts for their decreased serum levels.