An oxidation-resistant, recombinant Alpha-1 Antitrypsin produced in Nicotiana benthamiana

Publication date: Available online 16 March 2018
Source:Free Radical Biology and Medicine
Author(s): David Z. Silberstein, Kalimuthu Karuppanan, Hnin Hnin Aung, Ching-Hsien Chen, Carroll E. Cross, Karen A. McDonald
Proteases and reactive oxygen species (ROS) have long been implicated in playing key roles in host tissue injury at sites of inflammatory processes dominated by macrophage activations and/or neutrophil infiltrations. Imbalances between proteases/antiproteases and ROS/antioxidants are recognized to contribute to amplification of inflammatory-based host tissue injury. This has been especially well-documented in such respiratory tract diseases as chronic obstructive pulmonary disease, cystic fibrosis, and acute respiratory distress syndrome. Inflammation-related protease/ROS disequilibria are further confounded by recognition that proteases can increase ROS by several different mechanisms and that ROS can inactivate proteases.The major human antiprotease, alpha-1 antitrypsin (AAT), is dramatically inactivated by ROS. AAT deficiency represents the most prevalent genetic predisposing factor leading to emphysema, a condition treated by replacement infusions of plasma-derived AAT (hAAT) at a cost of up to $200,000 per year. An updated method for production of a plant-made recombinant AAT (prAAT) engineered for enhanced oxidation resistance compared to hAAT is presented. prAAT shows comparable antintiprotease activity to hAAT, and retains full activity under oxidative conditions that would deactivate hAAT. Additionally, we show that prAAT has similar effectiveness in preventing neutrophil elastase-induced cell death in an in vitro human bronchial epithelial cell culture model. We conclude that prAAT potentially presents a viable method for the development of a "biobetter" AAT product that could be made available to subjects with a wide spectrum of inflammatory disorders characterized by overly aggressive neutrophilic infiltrations.

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