Alpha-1 Antitrypsin Deficiency: Recent Developments in Gene Therapy Research

Alpha-1 antitrypsin (AAT) deficiency is a hereditary disorder associated with mutations in the SERPINA1 gene (Kelly et al., 2008; Greene et al., 2008). Over 100 different alleles have been identified however the most common disease-causing mutation, termed Z, encodes a glutamic acid to lysine substitution at position 342 of the mature AAT protein. As a member of the serine proteinase inhibitor family, the role of AAT is to inhibit serine proteases throughout the body but principally in the lung. The ZAAT protein fails to adopt the correct protein conformation and polymerises and accumulates intracellularly in AAT-producing cells. The liver is the major source of the body’s pool of AAT. The major consequences of ZAAT accumulation in hepatocytes are toxic gain of function events leading to endoplasmic reticulum (ER) expansion and dilation and activation of multiple ER stress signalling pathways (Lomas et al., 1992; Teckman & Perlmutter, 2000; Lawless et al., 2004; Hidvegi et al., 2005; Hidvegi et al., 2007; Miller et al., 2007). These predispose to liver failure. The second major clinical consequence of ZAAT deficiency is a lower than normal antiprotease protective screen throughout the body, but most importantly in the lung (Lomas et al., 1993). ZAAT deficient individuals can develop emphysematous lung disease as early as in their 4th decade. Gene therapies to treat both aspects of the disease are currently at various stages of development. For the liver disease approaches that can be considered include ribozymes, antisense, peptide nucleic acids and small-interfering RNAs; all designed to inhibit expression of the mutant gene (recently reviewed in McLean et al., 2009). For the lung disease gene therapies using non-viral, lentiviral and adeno-associated viral approaches to express the normal gene either locally or intramuscularly have been reported (Chulay et al., 2011; Brantly et al., 2006; Flotte et al., 2007; Argyros et al., 2008; Brantly et al., 2009; Liqun Wang et al., 2009); all aim to increase AAT levels in the circulation above the deficiency threshold of 11 μM. New approaches are focused on coupling haematopoietic stem cell therapy with AAT-lentiviral gene therapy (Ghaedi et al., 2010; Argyros et al., 2008). This chapter will review the history and current state-of-the-art in these areas.</p

Gene targeted therapeutics for liver disease in alpha-1 antitrypsin deficiency

Alpha-1 antitrypsin (A1AT) is a 52 kDa serine protease inhibitor that is synthesized in and secreted from the liver. Although it is present in all tissues in the body the present consensus is that its main role is to inhibit neutrophil elastase in the lung. A1AT deficiency occurs due to mutations of the A1AT gene that reduce serum A1AT levels to <35% of normal. The most clinically significant form of A1AT deficiency is caused by the Z mutation (Glu342Lys). ZA1AT polymerizes in the endoplasmic reticulum of liver cells and the resulting accumulation of the mutant protein can lead to liver disease, while the reduction in circulating A1AT can result in lung disease including early onset emphysema. There is currently no available treatment for the liver disease other than transplantation and therapies for the lung manifestations of the disease remain limited. Gene therapy is an evolving field which may be of use as a treatment for A1AT deficiency. As the liver disease associated with A1AT deficiency may represent a gain of function possible gene therapies for this condition include the use of ribozymes, peptide nucleic acids (PNAs) and RNA interference (RNAi), which by decreasing the amount of aberrant protein in cells may impact on the pathogenesis of the condition

Candida species in cystic fibrosis: A road less travelled.

Candida species are isolated with high frequency from cystic fibrosis patients, yet their definitive role in the disease remains unclear. Previously considered to have minimal inherent virulence owing to their commensal ability, the last decade has heralded an increasing recognition of Candida infection among patients with cystic fibrosis. What has been more recently hypothesized is that the organism possesses virulence factors that play diverse roles at different body sites during varied stages of an infection. Currently, limited data is accessible in the area of cystic fibrosis. This review aims to provide an overview of the role of Candida species in cystic fibrosis as it is currently understood including the common local and systemic infections observed in clinical practice. The uncertain role of airway colonization and insight into emerging fields such as Candida-bacterial interactions are also addressed. Finally, we outline the current understanding of the innate, cellular and humoral immune responses associated with this genus which has been the major focus of work performed to date

An analysis of student engagement when taught in classes of different sizes in rural, regional and metropolitan campuses of an Australian university

This study investigates the impact of class size on student engagement and student performance. It is based on an analysis of student university enter scores, student grades and student evaluations in metropolitan, regional and rural campuses of an Australian universityduring trimester 1 of years 2008, 9 &amp; 10. Past literature appears to support the predominant influence of the class size effect on learning, though some findings are mixed and inconclusive. Contrary to the accepted view that higher entry level scores result in higher grades and, conversely, lower entry level scores result in lower grades, the findings suggest that factorsother than entry level scores, contribute to student outcomes and student engagement. The study reveals that student satisfaction of teaching quality is higher in the rural and regional campuses where the cohorts are smaller than at the metropolitan campus. This may be an indication that class size seems to have a predominant influence on student engagement and learning outcomes.<br /

MicroRNAs in inflammatory lung disease - master regulators or target practice?

MicroRNAs (miRNAs) have emerged as a class of regulatory RNAs with immense significance in numerous biological processes. When aberrantly expressed miRNAs have been shown to play a role in the pathogenesis of several disease states. Extensive research has explored miRNA involvement in the development and fate of immune cells and in both the innate and adaptive immune responses whereby strong evidence links miRNA expression to signalling pathways and receptors with critical roles in the inflammatory response such as NF-κB and the toll-like receptors, respectively. Recent studies have revealed that unique miRNA expression profiles exist in inflammatory lung diseases such as cystic fibrosis, chronic obstructive pulmonary disease, asthma, idiopathic pulmonary fibrosis and lung cancer. Evaluation of the global expression of miRNAs provides a unique opportunity to identify important target gene sets regulating susceptibility and response to infection and treatment, and control of inflammation in chronic airway disorders. Over 800 human miRNAs have been discovered to date, however the biological function of the majority remains to be uncovered. Understanding the role that miRNAs play in the modulation of gene expression leading to sustained chronic pulmonary inflammation is important for the development of new therapies which focus on prevention of disease progression rather than symptom relief. Here we discuss the current understanding of miRNA involvement in innate immunity, specifically in LPS/TLR4 signalling and in the progression of the chronic inflammatory lung diseases cystic fibrosis, COPD and asthma. miRNA in lung cancer and IPF are also reviewed

The role of proteases, endoplasmic reticulum stress and SERPINA1 heterozygosity in lung disease and α-1 anti-trypsin deficiency.

The serine proteinase inhibitor α-1 anti-trypsin (AAT) provides an antiprotease protective screen throughout the body. Mutations in the AAT gene (SERPINA1) that lead to deficiency in AAT are associated with chronic obstructive pulmonary diseases. The Z mutation encodes a misfolded variant of AAT that is not secreted effectively and accumulates intracellularly in the endoplasmic reticulum of hepatocytes and other AAT-producing cells. Until recently, it was thought that loss of antiprotease function was the major cause of ZAAT-related lung disease. However, the contribution of gain-of-function effects is now being recognized. Here we describe how both loss- and gain-of-function effects can contribute to ZAAT-related lung disease. In addition, we explore how SERPINA1 heterozygosity could contribute to smoking-induced chronic obstructive pulmonary diseases and consider the consequences

Factors Affecting Prognosis and Prediction of Outcome in Cystic Fibrosis Lung Disease

Cystic fibrosis (CF) is a multisystem disorder with a significantly shortened life expectancy with the major cause of mortality related to lung disease. Inflammation is seen in the CF airways from a very early age and contributes significantly to symptoms and disease progression. As the condition worsens over time, lung function declines, usually measured by Forced Expiratory Volume in 1 second (FEV1)% predicted, and extra-pulmonary complications often manifest. While the life expectancy in CF is still short, the median age of death and predicted survival age are continually increasing. Therapeutic interventions for CF have improved significantly in the last 20 years and now there are targeted therapies towards specific elements in CF that may impact upon exacerbation frequency, symptoms, and eventually mortality due to lung disease

Hypertonic Saline in Treatment of Pulmonary Disease in Cystic Fibrosis

The pathogenesis of lung disease in cystic fibrosis is characterised by decreased airway surface liquid volume and subsequent failure of normal mucociliary clearance. Mucus within the cystic fibrosis airways is enriched in negatively charged matrices composed of DNA released from colonizing bacteria or inflammatory cells, as well as F-actin and elevated concentrations of anionic glycosaminoglycans. Therapies acting against airway mucus in cystic fibrosis include aerosolized hypertonic saline. It has been shown that hypertonic saline possesses mucolytic properties and aids mucociliary clearance by restoring the liquid layer lining the airways. However, recent clinical and bench-top studies are beginning to broaden our view on the beneficial effects of hypertonic saline, which now extend to include anti-infective as well as anti-inflammatory properties. This review aims to discuss the described therapeutic benefits of hypertonic saline and specifically to identify novel models of hypertonic saline action independent of airway hydration