Shane O’Neill

α1-antitrypsin deficiency: Biological answers to clinical questions

&agr;1-antitrypsin (&agr;1AT) deficiency is a common lethal hereditary disorder of white persons of European descent. The condition is characterized by reduced serum levels of &agr;1AT, a 52-kDa glycoprotein synthesized chiefly in the liver and, to a lesser extent, by macrophages and neutrophils. &agr;1AT acts as an antiprotease and is the physiological inhibitor of neutrophil serine proteases such as neutrophil elastase cathepsin G and proteinase 3. The clinical manifestations of &agr;1AT deficiency occur chiefly in the lung, with a high risk of emphysema occurring by the third or fourth decade of life. Cigarette smoking accelerates the development of emphysema in persons with &agr;1AT deficiency. There is also an increased risk of liver disease in &agr;1AT deficiency, which occurs mostly in childhood. In this review, we will define further the diagnosis of &agr;1AT deficiency and its clinical manifestations and describe the therapeutic strategies that are currently being developed to treat the hepatic and pulmonary disease associated with this condition.

Clarification of the Risk of Chronic Obstructive Pulmonary Disease in α1-Antitrypsin Deficiency PiMZ Heterozygotes

RATIONALE Severe α1-antitrypsin deficiency (typically PiZZ homozygosity) is associated with a significantly increased risk of airflow obstruction and emphysema but the risk of chronic obstructive pulmonary disease (COPD) in PiMZ heterozygotes remains uncertain. OBJECTIVES This was a family-based study to determine the risk of COPD in PiMZ individuals. METHODS We compared 99 PiMM and 89 PiMZ nonindex subjects recruited from 51 index probands who were confirmed PiMZ heterozygotes and also had a diagnosis of COPD Global Initiative for Chronic Obstructive Lung Disease stage II-IV. The primary outcome measures of interest were quantitative variables of pre- and post-bronchodilator FEV1/FVC ratio, FEV1 (liters), FEV1 (% predicted), forced expiratory flow midexpiratory phase (FEF25-75; liters per second), FEF25-75 (% predicted), and a categorical outcome of COPD. MEASUREMENTS AND MAIN RESULTS PiMZ heterozygotes compared with PiMM individuals had a reduced median (interquartile range) post-bronchodilator FEV1 (% predicted) (92.0 [75.6-105.4] vs. 98.6 [85.5-109.7]; P = 0.04), FEV1/FVC ratio (0.75 [0.66-0.79] vs. 0.78 [0.73-0.83]; P = 0.004), and FEF25-75 (% predicted) (63.84 [38.45-84.35] vs. 72.8 [55.5-97.7]; P = 0.0013) compared with PiMM individuals. This effect was abrogated in never-smoking and accentuated in ever-smoking PiMZ individuals. PiMZ heterozygosity was associated with an adjusted odds ratio for COPD of 5.18 (95% confidence interval, 1.27-21.15; P = 0.02) and this was higher (odds ratio, 10.65; 95% confidence interval, 2.17-52.29; P = 0.004) in ever-smoking individuals. CONCLUSIONS These results indicate that PiMZ heterozygotes have significantly more airflow obstruction and COPD than PiMM individuals and cigarette smoke exposure exerts a significant modifier effect.

Isolation and identification of cell-specific microRNAs targeting a messenger RNA using a biotinylated anti-sense oligonucleotide capture affinity technique

MicroRNAs (miRNAs) are small non-coding RNAs that regulate expression by translational repression or messenger RNA (mRNA) degradation. Although numerous bioinformatic prediction models exist to identify miRNA–mRNA interactions, experimental validation of bona fide interactions can be difficult and laborious. Few methods can comprehensively identify miRNAs that target a single mRNA. We have developed an experimental approach to search for miRNAs targeting any mRNA using a capture affinity assay involving a biotinylated DNA anti-sense oligonucleotide. This method identifies miRNAs targeting the full length of the mRNA. The method was tested using three separate mRNA targets: alpha-1 antitrypsin (AAT) mRNA, interleukin-8 mRNA and secretory leucoprotease inhibitor mRNA. AAT mRNA-specific and total miRNAs from three different cell lines (monocytic THP-1, bronchial epithelial 16HBE14o− and liver HepG2 cells) were profiled, and validation studies revealed that AAT mRNA-specific miRNAs functionally target the AAT mRNA in a cell-specific manner, providing the first evidence of innate miRNAs selectively targeting and modulating AAT mRNA expression. Interleukin-8 and secretory leucoprotease inhibitor mRNAs and their cognate miRNAs were also successfully captured using this approach. This is a simple and an efficient method to potentially identify miRNAs targeting sequences within the full length of a given mRNA transcript.

Local Impairment of Anti–Neutrophil Elastase Capacity in Community-Acquired Pneumonia

Protease-antiprotease balance in 17 patients with unilateral community-acquired pneumonia (CAP) was characterized (day 6+/-0.8). Levels and activities of alpha-1 antitrypsin (A1AT), secretory leucoprotease inhibitor (SLPI), and neutrophil elastase (NE) were quantified. Lobes were designated as infected or uninvolved according to the presence of an infiltrate on chest radiograph. NE levels in infected lobes were higher than those in uninvolved lobes, and NE levels were significantly elevated in both, compared with that in control lobes (n=18; P<.01). A1AT and SLPI levels were similar in infected and uninvolved lobes and were significantly elevated, compared with those in control lobes (P<.05 and P<.005, respectively). Anti-NE activity in infected lobes was less than that in control or uninvolved lobes (P<.05); values in the latter 2 were similar. Free NE was detected in 7 of the infected samples, indicating that anti-NE capacity is impaired. Both A1AT and SLPI were cleaved or complexed in infected lobes, and A1AT was oxidized in infected lobes. We conclude that mean elastase levels are increased and that mean anti-elastase capacity is decreased in pneumonic lobes.

Tumor Necrosis Factor–α–Converting Enzyme: Its Role in Community-Acquired Pneumonia

Bronchoalveolar lavage fluid recovered from infected and uninvolved lungs of patients with community-acquired pneumonia (CAP; ) on day was analyzed for cytokine, n p 16 6 0.8 soluble receptor, and antagonist levels. The role of tumor necrosis factor (TNF)–a–converting enzyme (TACE) in the resolution of the local inflammatory response was investigated. TNFa, interleukin (IL)–1b, and IL-6 were elevated in the infected versus uninvolved lobe, whereas IL-10 was not. Epithelial lining fluid (ELF) cytokine levels correlated with intracellular cytokine expression. Levels of proTNF-a were reciprocally related to TNF-a ELF levels. Levels of soluble receptors, generated by TACE cleavage of membrane-bound precursors, were compartmentalized to infected ELF. TACE was down-regulated by internalization in cells from the site of infection. These data demonstrate that, in vivo during CAP, TACE has a role in regulating resolution of the local inflammatory response by modulating levels of pro- and counterinflammatory mediators. Community-acquired pneumonia (CAP) is a common condition characterized by a high burden of morbidity and mortality. CAP rates among the 6 most common causes of death in the United States, where 2–3 million cases occur annually. The percentage of mortality among hospitalized patients ranges from 2% to 30% but is !1% for patients not requiring hospitalization [1–5]. The critical factors responsible for immunoregulation in the lung and the variation in response and outcome among different patients require a balance between endogenously generated pro- and anti-inflammatory mediators. Among the most important proinflammatory mediators in CAP are tumor necrosis factor (TNF)–a, interleukin (IL)–1b, and IL-6 [6–9], whereas IL-10 has been suggested to be critical in counterbalancing their effects and achieving adequate resolution of the septic process [10]. TNF-a is produced as a 26-kDa membrane-associated protein (proTNF-a), which is cleaved enzymatically by TNF-a–converting enzyme (TACE) into a soluble 17.5-kDa cytokine [11]. It is a pleiotropic early response proinflammatory cytokine capable of inducing IL-1b and IL

Nitinol stent insertion for post-pneumonectomy syndrome

Post-pneumonectomy syndrome is an unusual condition, that can occur a variable period of time after a patient has had a pneumonectomy. Management of this syndrome has been described using a number of different techniques, often with considerable mortality. We present a case report where this condition was treated successfully by insertion of an expandable Nitinol stent. This is the first time this technique has been described to treat this condition, and we feel it may be the procedure of choice in managing these patients.