Recent insights into human bronchial proteomics - how are we progressing and what is next?

INTRODUCTION: The human respiratory system is highly prone to diseases and complications. Many lung diseases, including lung cancer (LC), tuberculosis (TB), and chronic obstructive pulmonary disease (COPD) have been among the most common causes of death worldwide. Cystic fibrosis (CF), the most common genetic disease in Caucasians, has adverse impacts on the lungs. Bronchial proteomics plays a significant role in understanding the underlying mechanisms and pathogenicity of lung diseases and provides insights for biomarker and therapeutic target discoveries. Areas covered: We overview the recent achievements and discoveries in human bronchial proteomics by outlining how some of the different proteomic techniques/strategies are developed and applied in LC, TB, COPD, and CF. Also, the future roles of bronchial proteomics in predictive proteomics and precision medicine are discussed. Expert commentary: Much progress has been made in bronchial proteomics. Owing to the advances in proteomics, we now have better ability to isolate proteins from desired cellular compartments, greater protein separation methods, more powerful protein detection technologies, and more sophisticated bioinformatic techniques. These all contributed to our further understanding of lung diseases and for biomarker and therapeutic target discoveries.

Mechanisms of exercise-induced bronchoconstriction in athletes: Current perspectives and future challenges.

The evidence of exercise-induced bronchoconstriction (EIB) without asthma (EIBwA ) occurring in athletes led to speculate about different endotypes inducing respiratory symptoms within athletes. Classical postulated mechanisms for bronchial obstruction in this population include the osmotic and the thermal hypotheses. More recently, the presence of epithelial injury and inflammation in the airways of athletes was demonstrated. In addition, neuronal activation has been suggested as a potential modulator of bronchoconstriction. Investigation of these emerging mechanisms is of major importance as EIB is a significant problem for both recreational and competitive athletes and is the most common chronic condition among Olympic athletes, with obvious implications for their competing performance, health and quality of life. Hereby, we summarize the latest achievements in this area and identify the current gaps of knowledge so that future research heads toward better defining the etiologic factors and mechanisms involved in development of EIB in elite athletes as well as essential aspects to ultimately propose preventive and therapeutic measures.

Tracheobronchial amyloidosis and confocal endomicroscopy.

Tracheobronchial amyloidosis is one of many causes of endobronchial stenosis and nodularity, the concrete diagnosis of which currently requires the finding of apple-green birefringence from endobronchial biopsies. Bronchoscopic probe-based confocal endomicroscopy (pCLE) is a novel optical biopsy technique which provides real-time images of the lattice structure of the bronchial basement membrane - a finding lost in malignancy. This case study outlines the imperfect, essentially palliative management of this rare disease, and shows for the first time the unusual dappled in vivo pCLE images of amyloid-affected endobronchium.

Functional properties of mixed cystic fibrosis and normal bronchial epithelial cell cultures.

Cystic fibrosis (CF) airway epithelia exhibit altered Cl(-) and Na(+) transport properties and increased IL-8 secretion. In the present study, we examined whether a small proportion of cells with a normal phenotype could normalize the ion transport and IL-8 secretion properties of a CF airway epithelial cell layer. We obtained three types of primary cultures of human bronchial epithelial cells: one composed of 100% non-CF cells, one of 100% CF cells, and one of 10% non-CF and 90% CF cells ("cocultures"). Measurement of the bioelectric properties in Ussing chambers revealed that the cocultures displayed Cl(-) and Na(+) transports similar to those observed in the 100% non-CF cultures and significantly different from CF cultures. IL-8 concentration in the coculture supernatant was not different from non-CF cultures, but was significantly lower than in CF cultures. This study provides evidence that 10% bronchial epithelial cells expressing a normal phenotype are sufficient to functionally correct a primary culture of CF bronchial epithelial cells in vitro. We postulate that 10% cells with a non-CF phenotype can be used as a goal for the design of gene therapy and cell therapy trials for CF lung disease.

Mannose-binding lectin is present in the infected airway: a possible pulmonary defence mechanism.

BACKGROUND: Mannose-binding lectin (MBL) deficiency has been associated with infections of the respiratory tract and with increased disease severity in cystic fibrosis (CF). The mechanism is uncertain, and could relate either to systemic or local effects. The aim of this study was to determine, in a large cohort of children, whether MBL is present on the airway surface in health or disease. METHODS: Bronchoalveolar lavage (BAL) fluid from children with and without respiratory infection (some with underlying disease) was analysed for MBL and neutrophil elastase (NE). Levels were compared between groups, and correlations were examined with local and systemic inflammatory markers, infective organisms and load. RESULTS: 85 children were recruited to the study. MBL was absent in the lavage of all 7 children without lung infection but present in 62% (8/13) of those with acute pneumonia/pneumonitis, 23% (5/22) with recurrent respiratory tract infections, 17% (1/6) with primary ciliary dyskinesia and 8% (3/37) with CF (p<0.01). Children with acute pneumonia/pneumonitis had significantly higher levels than those in the other groups. There was no relationship with organisms cultured or systemic markers of inflammation, although in the group with detectable MBL in the BAL fluid, the levels correlated positively with levels of NE. CONCLUSIONS: MBL is undetectable in the non-infected airway but is present in a significant number of samples from children with lung infection. The levels found in the BAL fluid could be physiologically active and the protein may therefore be playing a role in host defence.

Afghanistan Particulate Matter Enhances Pro-Inflammatory Responses in IL-13-Exposed Human Airway Epithelium via TLR2 Signaling.

Since the start of Afghanistan combat operations in 2001, there has been an increase in complaints of respiratory illnesses in deployed soldiers with no previous history of lung disorders. It is postulated that deployment-related respiratory illnesses are the result of inhalation of desert particulate matter (PM) potentially acting in combination with exposure to other pro-inflammatory compounds. Why some, but not all, soldiers develop respiratory diseases remains unclear. Our goal was to investigate if human airway epithelial cells primed with IL-13, a type 2 inflammatory cytokine, demonstrate stronger pro-inflammatory responses to Afghanistan desert PM (APM). Primary human brushed bronchial epithelial cells from non-deployed, healthy subjects were exposed to APM, both with and without IL-13 pretreatment. APM exposure in conjunction with IL-13 resulted in significantly increased expression of IL-8, a pro-inflammatory cytokine involved in neutrophil recruitment and activation. Furthermore, expression of TLR2 mRNA was increased after combined IL-13 and APM exposure. siRNA-mediated TLR2 knockdown dampened IL-8 production after exposure to APM with IL-13. APM with IL-13 treatment increased IRAK-1 (a downstream signaling molecule of TLR2 signaling) activation, while IRAK-1 knockdown effectively eliminated the IL-8 response to APM and IL-13. Our data suggest that APM exposure may promote neutrophilic inflammation in airways with a type 2 cytokine milieu.

Effects of arachidonic acid, monohydroxyeicosatetraenoic acid and prostaglandins on the release of mucous glycoproteins from human airways in vitro.

Human lung explants maintained in culture for 7 d incorporate [(3)H]glucosamine into mucous glycoproteins. Ethanol-precipitable, glucosamine-labeled mucous secretion was measured, and the effects of different pharmacologic agents upon this secretion were investigated. Anaphylaxed human lung generates prostaglandin (PG) synthesis and increased mucous release. Arachidonic acid (AA), PGA(2), PGD(2), and PGF(2alpha) significantly increased mucous glycoprotein release, whereas PGE(2) significantly reduced release. Evidence which suggests that lipoxygenase products of AA augment mucous release includes the following: (a) Nonsteroidal anti-inflammatory drugs (NSAID: acetylsalicylic acid and indomethacin) increase mucous release while preventing prostaglandin formation. (b) The increase in mucous release induced by AA or NSAID is additive once the agents are combined. (c) Several nonspecific lipoxygenase inhibitors (eicosa-5,8,11,14-tetraynoic acid; vitamin E; nordihydroguaiaretic acid; and alpha-naphthol) inhibit mucous release. Three additional lines of evidence directly indicate that monohydroxyeicosatetraenoic acid (HETE) causes increased mucous release: (a) the addition of a mixture of synthetic HETE (24-600 nM) increases mucous release; (b) pure 12-HETE (1-100 nM) also increases mucous release; (c) mucous release is increased synergistically by the combination of HETE and NSIAD. These data taken together demonstrate that HETE are capable of increasing mucous release and that conditions which may influence HETE production alter mucous release. Thus, although not directly demonstrating HETE production by human airways, the data strongly suggest that lipoxygenase products of AA in airways may profoundly influence mucous release; and it seems possible that lipoxygenase inhibitors may have a role in treating bronchorrhea.

Single-dose montelukast or salmeterol as protection against exercise-induced bronchoconstriction.

BACKGROUND AND OBJECTIVE: It has been previously established that montelukast provides protection against exercise-induced bronchoconstriction (EIB) after a single dose. The present objective was to assess the onset and duration of this protective action in a trial that included both positive and negative controls. METHODS: A randomized, active-controlled and placebo-controlled, double-blind, double-dummy, three-way crossover study was conducted in 47 patients (age range, 15 to 44 years) in whom there was a 20 to 40% fall in FEV(1) following exercise (DeltaFEV(1)). In randomized sequence, patients received oral montelukast (10 mg), placebo, or inhaled salmeterol (50 microg) as a positive control. Dosing was followed by exercise challenges at 2, 8.5, and 24 h. The primary end point was maximum DeltaFEV(1) at 2 h postdose. Secondary end points included maximum DeltaFEV(1) at the two later time points, and other measures (including recovery time and need for beta-agonist rescue) at all time points. RESULTS: The maximum DeltaFEV(1) magnitudes at 2, 8.5, and 24 h were significantly smaller after montelukast administration than after placebo administration (least squares mean [+/- SE], 13.2 +/- 1.2%, 11.7 +/- 1.2%, and 10.0 +/- 1.1% vs 21.8 +/- 1.2%, 16.8 +/- 1.3%, and 14.0 +/- 1.1%, respectively; p

Overexpression of cyclins D1 and E is frequent in bronchial preneoplasia and precedes squamous cell carcinoma development.

Increased protein expression of the G1 cyclins D1 and E is reported in invasive non-small cell lung carcinoma. However, during transformation of the bronchial epithelium, overexpression of these species occurs, and their relationship to aberrant expression of p53 and retinoblastoma (Rb) has not been described previously. To determine the expression of these cell cycle regulators during the development of invasive squamous cell carcinoma (SCC) of the lung, the immunohistochemical expression patterns in normal bronchial epithelium (n = 36), squamous metaplasia (SM; n = 28), and epithelial atypia (n = 34) were compared with that in low-grade dysplasia (LGD; n = 17), high-grade bronchial dysplasia (HGD; n = 30), and SCC (n = 36). Monoclonal anti-p53 Pab1801, polyclonal anti-cyclin D1 DCS6, monoclonal anti-cyclin E HE12, and monoclonal anti-Rb OP-66 antibodies were used. Cyclin D1 was not expressed in normal bronchial epithelium but was detected in 7% of SMs, 15% of atypias; 18% of LGDs, 47% of HGDs, and 42% of SCCs. Cyclin E was not detected in normal epithelium (n = 24), SM (n = 16), or LGD (n = 12), but it was found in 9% of atypias (2 of 22), 33% of HGDs (7 of 21), and 54% of SCCs (13 of 24). p53 was not expressed in normal epithelium, SM, and LGD, but it was overexpressed in 6% of atypias, 53% of HGDs, and 61% of SCCs. Abnormal Rb expression was found only in 2 of 36 cases of SCC. A total of 91% of HGDs and 92% of SCCs exhibited overexpression of at least one of the p53, cyclin D1, or cyclin E species. However, no link was observed between overexpression of p53 and the overexpressed G1 cyclins in preneoplastic lesions. Overexpression of cyclin D1, cyclin E, and p53 occurs frequently and independently in pulmonary SCC and is detected in lesions before the development of invasive carcinoma. In contrast, altered Rb expression is a late and infrequent event in squamous cell carcinogenesis.

Tracheobronchial AL amyloidosis: histologic, immunohistochemical, ultrastructural, and immunoelectron microscopic observations.

We have studied three cases of localized amyloidosis in the lower respiratory tract. Amyloid was nodularly or diffusely deposited in the lamina propria of the tracheobronchial mucosa. Its nature was confirmed by Congo red staining with green birefringence on polarized microscopy. "Tracheobronchopathia osteoplastica" also was demonstrated. Plasma cells and lymphocytes were scant in the amyloid mass. Few fibroblasts and even fewer macrophages were seen. The number of plasma cells was not increased in the bone marrow in any of our cases. Amyloid fibrils were demonstrated by electron microscopic examination. The amyloid P component was detected by immunohistochemical methods. The precursor protein of amyloidosis was shown to be amyloid L protein by the postembedding protein-A gold technique with anti-light chain antisera. The role of the plasma cells in amyloid formation, however, could not be ascertained. Based on these observations, amyloid fibril formation in tracheobronchial amyloidosis appears to be related to light chains secreted by local plasma cells, combined with amyloid P, calcium, and other factors.

Broncholith removal using the YAG laser.

An 85-year-old woman presented with a broncholith in the intermediate bronchus that could not be extracted with either flexible or rigid bronchoscopes. A YAG laser was used to fragment this broncholith so that it could be removed in pieces through a bronchoscope. Chemical composition and morphology of the broncholith were determined. Fragmentation of the large, impacted broncholith with the laser eliminated the necessity for a thoracotomy in this elderly woman.

Expression and localization of thrombomodulin in preneoplastic bronchial lesions and in lung cancer.

Thrombomodulin (TM) is an endothelial surface glycoprotein that acts as a natural anticoagulant. It inhibits thrombin and accelerates the activation of the anticoagulant protein C. TM has been detected in dermal keratinocytes, where it is associated with terminal differentiation. It can also be detected in various types of squamous malignant neoplasms and in malignancies of endothelial and mesothelial origin, such as Kaposi's sarcoma or malignant mesothelioma, but is absent in pulmonary adenocarcinomas (AC). Seventy-two lung tumour specimens [33 squamous cell carcinomas (SQCC), 23 AC, 1 large cell carcinoma, 8 small cell lung cancers (SCLC) and 7 multidifferentiated tumours (MT)] were analysed immunohistochemically by staining with an anti-TM antibody in order to assess TM expression. All of the SQCC stained positively for TM. In contrast, only 9 AC and 4 MT and none of the SCLC showed positive anti-TM staining. Seven hyperplastic bronchial epithelial specimens and eight preneoplastic bronchial lesions (five cases of moderate dysplasia, two cases of severe dysplasia and one case of carcinoma in situ) were used as controls. Normal or hyperplastic areas of bronchial epithelium revealed no positive reaction. However, a distinct positive anti-TM staining pattern related to the degree of keratiniziation of dysplastic lesions was seen. The present results suggest that anti-TM immunostaining is a useful marker for squamous cell carcinoma in the differential diagnosis of pulmonary carcinoma, also indicating keratinocyte differentiation in dysplastic bronchial epithelium.

Cyclin proteolysis as a retinoid cancer prevention mechanism.

The retinoids, natural and synthetic derivatives of vitamin A, are active in cancer therapy and prevention. Their biological effects are mediated through ligand-dependent interactions with retinoid receptors that associate with specific co-regulators. A better understanding of retinoid chemopreventive mechanisms is needed. Our prior work revealed that all-trans-retinoic acid (RA) prevented tobacco-specific carcinogenic transformation of cultured human bronchial epithelial cells. RA signaled G1 arrest that permitted repair of genomic DNA damage caused by these carcinogens. RA triggered G1 arrest at least partly through proteasome-dependent degradation of cyclin D1. Proteasomal inhibitors blocked RA-mediated cyclin D1 degradation. To confirm that a specific proteolysis pathway was induced by RA-treatment, a degradation assay was established using in vitro translated cyclin D1 and cellular extracts from RA-treated or untreated human bronchial epithelial cells. Incubation of RA-treated but not the control cellular extracts with in vitro translated cyclin D1 led to cyclin degradation. This degradation depended on the PEST domain of cyclin D1, implicating ubiquitination in this retinoid degradation. Retinoid receptor selective agonists demonstrated that retinoic acid receptor (RAR)beta and retinoid X receptor (RXR) but not RARalpha- or RARgamma-dependent pathways signaled this cyclin degradation. Findings were extended to the NT2/D1 human embryonal carcinoma differentiation model where a similar pathway was activated by RA-treatment. To determine whether G1 cyclins were involved directly in bronchial preneoplasia, immunohistochemical expression profiles for cyclins D1 and E were examined. Aberrant expression of these cyclins was frequent in bronchial preneoplasia. Taken together, these findings indicate that ubiquitin-dependent proteolysis of G1 cyclins is a retinoid chemoprevention mechanism. Whether the retinoids represent the optimal agents to activate this pathway is the subject of ongoing work. These findings provide a rationale for combining the retinoids in chemoprevention trials with other agents that do not activate this proteolysis pathway. What is now known about the retinoids as cancer prevention agents will be reviewed. Emphasis is placed on retinoid effects on cell cycle progression at G1.

Glycosaminoglycans in the bronchial mucus of patients with chronic bronchitis and mucoid impaction of the bronchus.

Glycosaminoglycans were isolated from mucus of patients with chronic bronchitis and mucoid impaction of the bronchus, whose contents were approximately 56 mumoles and 80 mumoles of hexosamine per g of dry weight of mucus respectively. Electrophoretic and chemical characterization and enzymatic susceptibility demonstrated that the glycosaminoglycans in mucus from both groups of the patients contained hyaluronic acid as the main constituent, with undersulphated chondroitin as a minor component. In addition, in mucus from the patient with mucoid impaction of the bronchus chondroitin sulphate and heparan sulphate or heparan sulphate-like substance were identified.

The influence of seaprose on erythromycin penetration into bronchial mucus in bronchopulmonary infections.

In bronchopulmonary infections antibiotics can be combined with other drugs, called mucoactive drugs, that act to reduce the abnormal viscoelasticity of the mucus enabling a deeper penetration of more antibiotic into the mucus. Seaprose is a protease that interacts with the polymeric fibrillar structure of the bronchial mucus to shorten the long chains of mucoproteins, DNA and other macromolecules, thus reducing the viscosity of the mucus. In order to assess whether the combination of seaprose (60 mg/8 h) plus erythromycin (500 mg/8 h) allows higher antibiotic levels in sputum than erythromycin (500 mg/8 h) plus placebo, the pharmacokinetic behaviour in sputum and in blood of these two treatments was investigated in a double-blind study in two groups of twenty patients each with bronchopulmonary infections. Serum and sputum levels were determined for each patient at the first and seventh day of the two drug regimens. Statistically significant differences for peak, AUC and MRT, were observed for erythromycin between the first and last dose in the group of patients treated with seaprose plus erythromycin; moreover significant differences for these parameters were observed between the two groups. These findings indicate the presence of a pharmacokinetic synergism between seaprose and erythromycin which allows erythromycin to penetrate bronchial secretion more easily and in higher amounts, performing a sterilizing action with therapeutic advantages.

Primary diffuse tracheobronchial amyloidosis in a dog.

Primary diffuse tracheobronchial amyloidosis was diagnosed at necropsy in an intact male Akita dog aged 11 years, a non-productive chronic cough having been the only related clinical sign. Histologically, eosinophilic hyalinized deposits were found as a band in the lamina propria underneath the epithelium of the trachea and bronchi. When stained with Congo red, apple-green birefringence was observed in the deposits viewed with polarized light. The amyloid did not lose sensitivity to Congo red staining after incubation with potassium permanganate, indicating that it was of the AL (amyloid light chain) type. Ultrastructural features of the amyloid included a typical fibrillar meshwork with individual fibrils measuring 9.5 to 10.5 nm in diameter. This is the first report of primary diffuse tracheobronchial amyloidosis in the dog.

RV11 (propionyl erythromycin mercaptosuccinate) pharmacokinetics in bronchial secretions.

The kinetics of RV11 (propionyl erythromycin mercaptosuccinate) in serum and bronchial secretions was investigated in heterogeneous bronchopneumopathic patients requiring diagnostic bronchoscopy. A single oral dose, equivalent to 500 mg of erythromycin base, was administered to all patients and the bronchial secretion and plasma concentrations were determined after 2, 3 and 4 hr. The bronchial secretion and plasma levels consistently exceeded those reported previously for erythromycin per os, suggesting that RV11 may have an unusually high affinity for bronchial secretions in humans. The results of this study also suggested that RV11 might have different kinetics in bronchial secretions and serum, though further studies are required to provide definitive evidence.

[Anomalies of mucus and bronchial pathology in adults]. / Anomalies du mucus et pathologie bronchique de l'adulte.

Recent studies have shown that normal bronchial secretion composed of proteoglycans, atypical glycoproteins and neutral lipids neither includes mucins nor glycolipids, nor phospholipids. The rheological characteristics of bronchial mucus thus depend on mucociliary clearance and clearance of bronchial secretions by cough, which in turn depend on the properties of the glycoprotein acids secreted and on the degree of their entanglement which is linked to their water content and on the chemical bonds with other protein or lipid components which are present in the secretions. Chronic bronchitis, asthma and bronchorrhoea allow for changes in the biochemical composition and the physical and rheological characteristics of the bronchial mucus which alter the clearance. In certain conditions mucus plugs can form. An understanding of the pathology of bronchial mucus in the adult enables one to choose the best therapeutic prescriptions but the efficacy of measurements available remains imperfect.