Identification and characterisation of eight novel SERPINA1 Null mutations.

BACKGROUND: Alpha-1 antitrypsin (AAT) is the most abundant circulating antiprotease and is a member of the serine protease inhibitor (SERPIN) superfamily. The gene encoding AAT is the highly polymorphic SERPINA1 gene, found at 14q32.1. Mutations in the SERPINA1 gene can lead to AAT deficiency (AATD) which is associated with a substantially increased risk of lung and liver disease. The most common pathogenic AAT variant is Z (Glu342Lys) which causes AAT to misfold and polymerise within hepatocytes and other AAT-producing cells. A group of rare mutations causing AATD, termed Null or Q0, are characterised by a complete absence of AAT in the plasma. While ultra rare, these mutations confer a particularly high risk of emphysema. METHODS: We performed the determination of AAT serum levels by a rate immune nephelometric method or by immune turbidimetry. The phenotype was determined by isoelectric focusing analysis on agarose gel with specific immunological detection. DNA was isolated from whole peripheral blood or dried blood spot (DBS) samples using a commercial extraction kit. The new mutations were identified by sequencing all coding exons (II-V) of the SERPINA1 gene. RESULTS: We have found eight previously unidentified SERPINA1 Null mutations, named: Q0cork, Q0perugia, Q0brescia, Q0torino, Q0cosenza, Q0pordenone, Q0lampedusa, and Q0dublin . Analysis of clinical characteristics revealed evidence of the recurrence of lung symptoms (dyspnoea, cough) and lung diseases (emphysema, asthma, chronic bronchitis) in M/Null subjects, over 45 years-old, irrespective of smoking. CONCLUSIONS: We have added eight more mutations to the list of SERPINA1 Null alleles. This study underlines that the laboratory diagnosis of AATD is not just a matter of degree, because the precise determination of the deficiency and Null alleles carried by an AATD individual may help to evaluate the risk for the lung disease.

Rare causes of persistent wheeze that mimic poorly controlled asthma.

Upper airway obstruction can present with stridor or expiratory or inspiratory wheeze and is commonly misdiagnosed as asthma. As asthma is common, such cases can remain hidden among patients with lower airway obstruction who attend primary care or respiratory clinics. We describe four causes of upper airway obstruction (paradoxical vocal cord movement, subglottic stenosis, retrosternal goitre and double aortic arch) which were misdiagnosed as 'poorly controlled asthma'.

Eosinophil recruitment to nasal nerves after allergen challenge in allergic rhinitis.

In allergen challenged animal models, eosinophils localize to airway nerves leading to vagally-mediated hyperreactivity. We hypothesized that in allergic rhinitis eosinophils recruited to nasal nerves resulted in neural hyperreactivity. Patients with persistent allergic rhinitis (n=12), seasonal allergic rhinitis (n=7) and controls (n=10) were studied. Inferior nasal turbinate biopsies were obtained before, 8 and 48h after allergen challenge. Eight hours after allergen challenge eosinophils localized to nerves in both rhinitis groups; this was sustained through 48h. Bradykinin challenge, with secretion collection on the contralateral side, was performed to demonstrate nasal nerve reflexes. Twenty fourhours after allergen challenge, bradykinin induced a significant increase in secretions, indicating nasal hyperreactivity. Histological studies showed that nasal nerves expressed both vascular cell adhesion molecule-1 (VCAM-1) and chemokine (C-C motif) ligand 26 (CCL-26). Hence, after allergen challenge eosinophils are recruited and retained at nerves and so may be a mechanism for neural hyperreactivity.

Short palate, lung, and nasal epithelial clone-1 is a tightly regulated airway sensor in innate and adaptive immunity.

Short palate, lung, and nasal epithelial clone-1 (SPLUNC1) is a protein abundantly expressed by the respiratory epithelium of the proximal lower respiratory tract, a site of great environmental exposure. Previous studies showed that SPLUNC1 exerts antimicrobial effects, regulates airway surface liquid and mucociliary clearance, and suppresses allergic airway inflammation. We studied SPLUNC1 to gain insights into its role in host defense. In the lower respiratory tract, concentrations of SPLUNC1 are high under basal conditions. In models of pneumonia caused by common respiratory pathogens, and in Th1-induced and Th2-induced airway inflammation, SPLUNC1 secretion is markedly reduced. Pathogen-associated molecular patterns and IFN-γ act directly on airway epithelial cells to inhibit SPLUNC1 mRNA expression. Thus, SPLUNC1 is quickly suppressed during infection, in response to an insult on the epithelial surface. These experiments highlight the finely tuned fluctuations of SPLUNC1 in response to exposures in the respiratory tract, and suggest that the loss of SPLUNC1 is a crucial feature of host defense across air-breathing animal species.

Advances in mucous cell metaplasia: a plug for mucus as a therapeutic focus in chronic airway disease.

Mucous cell metaplasia is induced in response to harmful insults and provides front-line protection to clear the airway of toxic substances and cellular debris. In chronic airway diseases mucous metaplasia persists and results in airway obstruction and contributes significantly to morbidity and mortality. Mucus hypersecretion involves increased expression of mucin genes, and increased mucin production and release. The past decade has seen significant advances in our understanding of the molecular mechanisms by which these events occur. Inflammation stimulates epidermal growth factor receptor activation and IL-13 to induce both Clara and ciliated cells to transition into goblet cells through the coordinated actions of FoxA2, TTF-1, SPDEF, and GABA(A)R. Ultimately, these steps lead to up-regulation of MUC5AC expression, and increased mucin in goblet cell granules that fuse to the plasma membrane through actions of MARCKS, SNAREs, and Munc proteins. Blockade of mucus in exacerbations of asthma and chronic obstructive pulmonary disease may affect morbidity. Development of new therapies to target mucus production and secretion are now possible given the advances in our understanding of molecular mechanisms of mucous metaplasia. We now have a greater incentive to focus on inhibition of mucus as a therapy for chronic airway diseases.

Diabetes mellitus and bone disease in cystic fibrosis.

Patients with cystic fibrosis are frequently affected with pancreatic insufficiency and are predisposed to the development of diabetes mellitus (DM) and bone demineralization. Cystic fibrosis-related diabetes mellitus is a clinical entity distinct from type 1 and type 2 diabetes, with important implications for the nutritional and pulmonary health of cystic fibrosis patients. This form of diabetes owes largely to insulin deficiency, but alterations in insulin sensitivity and hepatic glucose production have also been described. Therapy for cystic fibrosis-related diabetes differs substantially from type 2 DM, with careful attention to prandial glycemic excursions crucial to controlling its metabolic effects. Bone disease, including osteopenia and osteoporosis, also occurs with increased frequency in cystic fibrosis, owing to defects in intestinal absorption, chronic inflammation, lung disease, low body weight, and gonadal dysfunction. The pathogenesis, implications, diagnosis, and therapy of cystic fibrosis-related bone demineralization are discussed, with attention to recommended approaches to prevention of and treatment of established bone disease.

Mechanism of eosinophil induced signaling in cholinergic IMR-32 cells.

Eosinophils interact with nerve cells, leading to changes in neurotransmitter release, altered nerve growth, and protection from cytokine-induced apoptosis. In part, these interactions occur as a result of activation of neural nuclear factor (NF)-kappaB, which is activated by adhesion of eosinophils to neural intercellular adhesion molecule-1 (ICAM-1). The mechanism and consequence of signaling after eosinophil adhesion to nerve cells were investigated. Eosinophil membranes, which contain eosinophil adhesion molecules but not other eosinophil products, were coincubated with IMR-32 cholinergic nerve cells. The studies showed that there were two mechanisms of activation of NF-kappaB, one of which was dependent on reactive oxygen species, since it was inhibited with diphenyleneiodonium. This occurred at least 30 min after coculture of eosinophils and nerves. An earlier phase of NF-kappaB activation occurred within 2 min of eosinophil adhesion and was mediated by tyrosine kinase-dependent phosphorylation of interleukin-1 receptor-associated kinase-1 (IRAK-1). Coimmunoprecipitation experiments showed that both extracellular signal-regulated kinase 1/2 and IRAK-1 were recruited to ICAM-1 rapidly after coculture with eosinophil membranes. This was accompanied by an induction of ICAM-1, which was mediated by an IRAK-1-dependent pathway. These data indicate that adhesion of eosinophils to IMR-32 nerves via ICAM-1 leads to important signaling events, mediated via IRAK-1, and these in turn lead to expression of adhesion molecules.

Eosinophil adhesion to cholinergic IMR-32 cells protects against induced neuronal apoptosis.

Eosinophils release a number of mediators that are potentially toxic to nerve cells. However, in a number of inflammatory conditions, such as asthma and inflammatory bowel disease, it has been shown that eosinophils localize to nerves, and this is associated with enhanced nerve activity. In in vitro studies, we have shown that eosinophil adhesion via neuronal ICAM-1 leads to activation of neuronal NF-kappaB via an ERK1/2-dependent pathway. In this study, we tested the hypothesis that eosinophil adhesion to nerves promotes neural survival by protection from inflammation-associated apoptosis. Exposure of differentiated IMR-32 cholinergic nerve cells to IL-1beta, TNF-alpha, and IFN-gamma, or culture in serum-deprived medium, induced neuronal apoptosis, as detected by annexin V staining, caspase-3 activation, and DNA laddering. Addition of human eosinophils to IMR-32 nerve cells completely prevented all these features of apoptosis. The mechanism of protection by eosinophils was by an adhesion-dependent activation of ERK1/2, which led to the induced expression of the antiapoptotic gene bfl-1. Adhesion to nerve cells did not influence the expression of the related genes bax and bad. Thus, prevention of apoptosis by eosinophils may be a mechanism by which these cells regulate neural plasticity in the peripheral nervous system.

Effect of eosinophil adhesion on intracellular signaling in cholinergic nerve cells.

Eosinophil localization to cholinergic nerves occurs in a variety of inflammatory conditions, including asthma. This localization is mediated by interactions between eosinophil integrins and neuronal vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1). Eosinophil-nerve cell interactions lead to generation of neuronal reactive oxygen species and release of eosinophil proteins. The effects of eosinophil adhesion on neuronal intracellular signaling pathways were investigated. Eosinophil adhesion to IMR32 cholinergic nerves led to a rapid and sustained activation of the nuclear transcription factors nuclear factor (NF)-kappaB and activator protein (AP)-1 in the nerve cells. Eosinophil binding to neuronal ICAM-1 led to a rapid activation of ERK1/2 in nerve cells. Inhibition of ERK1/2 prevented NF-kappaB activation. Eosinophil adhesion to VCAM-1 resulted in AP-1 activation, mediated partially by rapid activation of the p38 mitogen-activated protein kinase. These data show that adhesion of eosinophils induces mitogen-activated protein kinase-dependent activation of the transcription factors NF-kappaB and AP-1 in nerve cells, indicating that eosinophil adhesion may control nerve growth and phenotype.

Interactions between inflammatory cells and nerves.

In the lungs, motor parasympathetic nerves and sensory nerves both innervate a variety of inflammatory cells. Interactions between these cells provide a means of extending the influence of each other's function. Neurotransmitters influence inflammatory cell function by either augmenting or limiting the inflammatory response. On the other hand, chemical factors released from inflammatory cells lead to local, reflex and long-lasting central changes in neural function.