Gelsolin secretion in interleukin-4-treated bronchial epithelia and in asthmatic airways

Endotyping Chronic Obstructive Pulmonary Disease, Bronchiectasis, and the "Chronic Obstructive Pulmonary Disease-Bronchiectasis Association"

Rationale: Bronchiectasis and chronic obstructive pulmonary disease (COPD) are two disease entities with overlapped clinical features, and codiagnosis frequently occurs (termed the "COPD-bronchiectasis association"). Objectives: To investigate the sputum microbiome and proteome in patients with bronchiectasis, COPD, and the COPD-bronchiectasis association with the aim of identifying endotypes that may inform treatment. Methods: Sputum microbiome and protein profiling were carried out using 16S rRNA amplicon sequencing and a label-free proteomics workflow, respectively, in a cohort comprising patients with COPD (n = 43), bronchiectasis (n = 30), and the COPD-bronchiectasis association (n = 48). Results were validated in an independent cohort of 91 patients (n = 28-31 each group) using targeted measurements of inflammatory markers, mucins, and bacterial culture. Measurements and Main Results: Principal component analysis of sputum microbiome and protein profiles showed a partial separation between the COPD and the "COPD-bronchiectasis association" group. Further analyses revealed that patients with the "COPD-bronchiectasis association" had a higher abundance of proteobacteria, higher expression of mucin-5AC and proteins from the "neutrophil degranulation" pathway compared to those with COPD. In contrast, patients with COPD had an elevated expression of mucin-5B and several peptidase inhibitors, higher abundance of common commensal taxa, and a greater microbiome diversity. The profiles of "COPD-bronchiectasis association" and bronchiectasis groups were largely overlapping. Five endotypes were proposed with differential inflammatory, mucin, and microbiological features. The key features related to the "COPD-bronchiectasis association" were validated in an independent cohort. Conclusions: Neutrophilic inflammation, differential mucin expression, and Gram-negative infection are dominant traits in patients with the "COPD-bronchiectasis association."

Potential Metabolic Biomarkers in Adult Asthmatics

Asthma is the most common chronic airway inflammation, with multiple phenotypes caused by complicated interactions of genetic, epigenetic, and environmental factors. To date, various determinants have been suggested for asthma pathogenesis by a new technology termed omics, including genomics, transcriptomics, proteomics, and metabolomics. In particular, the systematic analysis of all metabolites in a biological system, such as carbohydrates, amino acids, and lipids, has helped identify a novel pathway related to complex diseases. These metabolites are involved in the regulation of hypermethylation, response to hypoxia, and immune reactions in the pathogenesis of asthma. Among them, lipid metabolism has been suggested to be related to lung dysfunction in mild-to-moderate asthma. Sphingolipid metabolites are an important mediator contributing to airway inflammation in obese asthma and aspirin-exacerbated respiratory disease. Although how these molecular variants impact the disease has not been completely determined, identification of new causative factors may possibly lead to more-personalized and precise pathway-specific approaches for better diagnosis and treatment of asthma. In this review, perspectives of metabolites related to asthma and clinical implications have been highlighted according to various phenotypes.

Long-term evolution of the epithelial cell secretome in preclinical 3D models of the human bronchial epithelium

The human bronchial epithelium is the first line of defense against atmospheric particles, pollutants, and respiratory pathogens such as the novel SARS-CoV-2. The epithelial cells form a tight barrier and secrete proteins that are major components of the mucosal immune response. Functional in vitro models of the human lung are essential for screening the epithelial response and assessing the toxicity and barrier crossing of drugs, inhaled particles, and pollutants. However, there is a lack of models to investigate the effect of chronic exposure without resorting to animal testing. Here, we developed a 3D model of the human bronchial epithelium using Calu-3 cell line and demonstrated its viability and functionality for 21 days without subculturing. We investigated the effect of reduced Fetal Bovine Serum supplementation in the basal medium and defined the minimal supplementation needed to maintain a functional epithelium, so that the amount of exogenous serum proteins could be reduced during drug testing. The long-term evolution of the epithelial cell secretome was fully characterized by quantitative mass spectrometry in two preclinical models using Calu-3 or primary NHBE cells. 408 common secreted proteins were identified while significant differences in protein abundance were observed with time, suggesting that 7-10 days are necessary to establish a mature secretome in the Calu-3 model. The associated Reactome pathways highlight the role of the secreted proteins in the immune response of the bronchial epithelium. We suggest this preclinical 3D model can be used to evaluate the long-term toxicity of drugs or particles on the human bronchial epithelium, and subsequently to investigate their effect on the epithelial cell secretions.

Low Plasma Gelsolin Concentrations in Chronic Granulomatous Disease

Plasma gelsolin (pGSN) is the secreted isoform of an intracellular actin remodeling protein found in high concentrations in human plasma. Clinical studies demonstrate reduced pGSN concentrations in several disease states, including severe trauma, burns, and sepsis. Markedly decreased pGSN concentrations in these conditions precede and predict adverse clinical outcomes. In this study, we measured pGSN in patients with chronic granulomatous disease (CGD), a primary immunodeficiency characterized by recurrent infections and dysregulated inflammation. pGSN was quantified using a sandwich ELISA in plasma from healthy volunteers, clinically stable CGD patients, and X-linked CGD carriers and in sera from 12 CGD patients undergoing bone marrow transplantation. pGSN was also quantified in healthy volunteers challenged with intravenous endotoxin. pGSN concentrations were lower in CGD patients without active infection or systemic inflammation compared with healthy control subjects. In CGD patients undergoing bone marrow transplantation, pGSN concentrations increased significantly following successful transplant. X-linked carriers of CGD had normal pGSN. Despite reduction of pGSN in CGD patients, we did not detect significant changes in pGSN over 24 h following challenge of healthy volunteers with intravenous endotoxin (4 ng/kg) that elicited a febrile response. We describe, for the first time, significantly lower pGSN in clinically stable patients with CGD compared with age- and sex-matched healthy volunteers. Low pGSN levels in CGD patients significantly increased following bone marrow transplantation. X-linked carriers of CGD had normal pGSN. In healthy volunteers challenged with intravenous endotoxin, pGSN is not an acute phase reactant.

The Airway Epithelium-A Central Player in Asthma Pathogenesis

Asthma is a chronic inflammatory airway disease characterized by variable airflow obstruction in response to a wide range of exogenous stimuli. The airway epithelium is the first line of defense and plays an important role in initiating host defense and controlling immune responses. Indeed, increasing evidence indicates a range of abnormalities in various aspects of epithelial barrier function in asthma. A central part of this impairment is a disruption of the airway epithelial layer, allowing inhaled substances to pass more easily into the submucosa where they may interact with immune cells. Furthermore, many of the identified susceptibility genes for asthma are expressed in the airway epithelium. This review focuses on the biology of the airway epithelium in health and its pathobiology in asthma. We will specifically discuss external triggers such as allergens, viruses and alarmins and the effect of type 2 inflammatory responses on airway epithelial function in asthma. We will also discuss epigenetic mechanisms responding to external stimuli on the level of transcriptional and posttranscriptional regulation of gene expression, as well the airway epithelium as a potential treatment target in asthma.

Reduced allergic lung inflammation and airway responsiveness in mice lacking the cytoskeletal protein gelsolin

Airway smooth muscle hyperresponsiveness associated with chronic airway inflammation leads to the typical symptoms of asthma including bronchoconstriction and wheezing. Asthma severity is associated with airway inflammation; therefore reducing airway inflammation is an important therapeutic target. Gelsolin is an actin capping and severing protein that has been reported to be involved in modulation of the inflammatory response. Using mice genetically lacking gelsolin, we evaluated the role of gelsolin in the establishment of house dust mite (HDM) antigen-induced allergic lung inflammation. The genetic absence of gelsolin was found to be protective against HDM sensitization, resulting in reduced lung inflammation, inflammatory cytokines and Muc5AC protein in bronchoalveolar lavage (BAL) fluid. The number of eosinophils, lymphocytes and interstitial macrophages in the BAL were increased after HDM sensitization in wild type mice, but were attenuated in gelsolin null mice. The observed attenuation of inflammation may be partly due to delayed migration of immune cells, because the reduced eosinophils in the BALs from gelsolin null mice compared to controls occurred despite similar amounts of the chemoattractant eotaxin. Splenic T cells demonstrated similar proliferation rates, but ex vivo alveolar macrophage migration was delayed in gelsolin null mice. In vivo, the reduced lung inflammation after HDM sensitization in gelsolin null mice was associated with significantly diminished airway resistance to inhaled methacholine compared with HDM-treated wild type mice. Our results suggest that modulation of gelsolin expression or function in selective inflammatory cell types that modulate allergic lung inflammation could be a therapeutic approach for asthma.

Plasma Gelsolin: Indicator of Inflammation and Its Potential as a Diagnostic Tool and Therapeutic Target

Gelsolin, an actin-depolymerizing protein expressed both in extracellular fluids and in the cytoplasm of a majority of human cells, has been recently implicated in a variety of both physiological and pathological processes. Its extracellular isoform, called plasma gelsolin (pGSN), is present in blood, cerebrospinal fluid, milk, urine, and other extracellular fluids. This isoform has been recognized as a potential biomarker of inflammatory-associated medical conditions, allowing for the prediction of illness severity, recovery, efficacy of treatment, and clinical outcome. A compelling number of animal studies also demonstrate a broad spectrum of beneficial effects mediated by gelsolin, suggesting therapeutic utility for extracellular recombinant gelsolin. In the review, we summarize the current data related to the potential of pGSN as an inflammatory predictor and therapeutic target, discuss gelsolin-mediated mechanisms of action, and highlight recent progress in the clinical use of pGSN.

Extracellular Actin in Health and Disease

This review considers the functions of extracellular actin - cell surface bound, associated with extracellular matrix, or freely circulating. The role of this protein in different pathological processes is analyzed: its toxic effects and involvement in autoimmune diseases as an autoantigen. The extracellular actin clearance system and its role in protection against the negative effects of actin are characterized. Levels of free-circulating actin, anti-actin immunoglobulins, and components of the actin clearance system as prognostic biomarkers for different diseases are reviewed. Experimental approaches to protection against excessive amounts of free-circulating F-actin are discussed.

The nasal methylome and childhood atopic asthma

BACKGROUND

Given the strong environmental influence on both epigenetic marks and allergic asthma in children, the epigenetic alterations in respiratory epithelia might provide insight into allergic asthma.

OBJECTIVE

We sought to identify DNA methylation and gene expression changes associated with childhood allergic persistent asthma.

METHODS

We compared genomic DNA methylation patterns and gene expression in African American children with persistent atopic asthma (n = 36) versus healthy control subjects (n = 36). Results were validated in an independent population of asthmatic children (n = 30) by using a shared healthy control population (n = 36) and in an independent population of white adult atopic asthmatic patients (n = 12) and control subjects (n = 12).

RESULTS

We identified 186 genes with significant methylation changes, differentially methylated regions or differentially methylated probes, after adjustment for age, sex, race/ethnicity, batch effects, inflation, and multiple comparisons. Genes differentially methylated included those with established roles in asthma and atopy and genes related to extracellular matrix, immunity, cell adhesion, epigenetic regulation, and airflow obstruction. The methylation changes were substantial (median, 9.5%; range, 2.6% to 29.5%). Hypomethylated and hypermethylated genes were associated with increased and decreased gene expression, respectively (P < 2.8 × 10^-6 for differentially methylated regions and P < 7.8 × 10^-10 for differentially methylated probes). Quantitative analysis in 53 differentially expressed genes demonstrated that 32 (60%) have significant methylation-expression relationships within 5 kb of the gene. Ten loci selected based on the relevance to asthma, magnitude of methylation change, and methylation-expression relationships were validated in an independent cohort of children with atopic asthma. Sixty-seven of 186 genes also have significant asthma-associated methylation changes in nasal epithelia of adult white asthmatic patients.

CONCLUSIONS

Epigenetic marks in respiratory epithelia are associated with allergic asthma and gene expression changes in inner-city children.

Strategies targeting the IL-4/IL-13 axes in disease

IL-4 and IL-13 are pleiotropic Th2 cytokines produced by a wide variety of different cell types and responsible for a broad range of biology and functions. Physiologically, Th2 cytokines are known to mediate host defense against parasites but they can also trigger disease if their activities are dysregulated. In this review we discuss the rationale for targeting the IL-4/IL-13 axes in asthma, atopic dermatitis, allergic rhinitis, COPD, cancer, inflammatory bowel disease, autoimmune disease and fibrotic disease as well as evaluating the associated clinical data derived from blocking IL-4, IL-13 or IL-4 and IL-13 together.

The plasma gelsolin levels in atopic dermatitis: Effect of atopy and disease severity

BACKGROUND

Gelsolin is an actin-binding protein with several cellular functions including anti-apoptosis and is reported to have an anti-inflammatory effect. Apoptosis of keratinocytes has been implicated as a key mechanism of atopic dermatitis (AD).

OBJECTIVE

We aimed to determine plasma gelsolin (pGSN) levels in children with atopic dermatitis (AD).

METHOD

The diagnosis of AD was made according to Hanifin and Rajka criteria. The disease severity was scored by objective SCORAD index by the same allergist. Skin prick testing (SPT), total IgE levels, and eosinophil counts were analyzed. The pGSN levels were determined using ELISA technique.

RESULTS

Children aged between 0.5 and 3.0 years were included in the study. The children with AD (AD; n=84) were analyzed in two groups according to the presence (AD+/Atopy+; n=54) or absence of SPT positivity (AD+/Atopy-; n=30). The comparisons were made with a healthy control group matched for age and sex (n=81). The median (interquartile range) of pGSN levels in AD+/A+, AD+/A- and control groups were 267μg/ml (236-368), 293 (240-498) and 547 (361-695), respectively (p<0.001). The difference between the control group and AD sub-groups remained significant after Bonferroni correction (p<0.001). Correlation analysis failed to reach significance with the disease severity total IgE levels and eosinophil counts.

CONCLUSION

This is the first study investigating the association of pGSN levels with AD and disease severity. pGSN levels decreased in AD. These findings suggest that gelsolin may have a role in the disease process in AD patients.

Fragmented gelsolins are increased in rheumatoid arthritis-associated interstitial lung disease with usual interstitial pneumonia pattern

BACKGROUND

Rheumatoid arthritis-associated interstitial lung disease (RA-ILD) occurs in 10%-30% of patients with RA, and interstitial lung disease (ILD) is associated with increased mortality in up to 10% of patients with RA. The pathogenesis of RA-ILD is virtually unknown. The aim of this study is to investigate the proteins related to UIP pattern by comparing to OP pattern in RA-ILD using proteome analysis of bronchoalveolar lavage fluid (BALF).

METHODS

Proteomic differences in BALF were compared between the UIP pattern and OP pattern by examining BALF from 5 patients with the UIP pattern and 7 patients with the OP pattern by two-dimensional gel electrophoresis and mass spectrometry.

RESULTS

In individual comparisons of BALF samples, the levels of the protein gelsolin and Ig kappa chain C region were significantly higher in the UIP pattern than in the OP pattern. In contrast, the levels of α-1 antitrypsin, CRP, haptoglobin β, and surfactant protein A (isoform number 5) were all significantly higher in the OP pattern than in the UIP pattern. Gelsolin was cleaved into two fragments, a C-terminal half and N-terminal half, and the levels of both were significantly higher in the UIP pattern than in the OP pattern.

CONCLUSIONS

Fragmented gelsolins may be associated with the pathogenesis of fibrosis in RA-ILD.

Allergen-specific immunotherapy increases plasma gelsolin levels

BACKGROUND

It has been observed that patients with allergic asthma/rhinitis have increased apoptosis of peripheral blood cells. This study was designed to explore the idea that the markers of apoptosis may help predict the response of allergen immunotherapy.

METHODS

The Allergy Department of University Hospital, Malmö, Sweden, recruited a total of 58 young adults (<35 years) with a history of birch pollen/grass pollen-induced allergic rhinitis. Their diagnoses were verified by positive skin-prick tests and the presence of serum-specific immunoglobulin E antibodies toward birch and/or grass pollen. Plasma samples were obtained from 34 patients before the start of immunotherapy and 24 patients after treatment. The control group consisted of 38 nonallergic individuals. The levels of plasma gelsolin, soluble forms of Fas (sFas) and Fas ligand (Fas-L), the chemokine CCL17 (thymus- and activation-regulated chemokine), and tissue inhibitor of metalloprotease (TIMP) 1, were measured by enzyme-linked immunosorbent assay.

RESULTS

In patients receiving immunotherapy plasma gelsolin levels were higher relative to those without immunotherapy (the median level was 23.97 μg/mL [range, 18-35.8 μg/mL] versus 21.2 μg/mL [range, 13.9-29.8 μg/mL]; p = 0.012) and were similar to those of healthy controls (24.7 μg/mL [range, 17.4-35.3 μg/mL]). Plasma levels of sFas, Fas-L, CCL17, and TIMP-1 did not differ between study groups. Only in controls did the plasma gelsolin levels inversely correlate to the levels of soluble Fas.

CONCLUSION

Allergen-specific immunotherapy increases plasma levels of gelsolin, an antioxidant and antiapoptotic protein.

Relationship between group-specific component protein and the development of asthma

RATIONALE

Airway inflammation and remodeling during asthma are attributed to the altered expression of biologically relevant proteins.

OBJECTIVES

To search for asthma-specific proteins in bronchoalveolar lavage fluid (BAL) from individuals with asthma and to validate the identified proteins in an experimental model of asthma.

METHODS

Liquid chromatography-tandem mass spectrometry was performed to identify proteins in BAL fluid found by two dimensional electrophoresis (2DE) to be differentially expressed in subjects with asthma versus control subjects. Group-specific component (Gc) and mRNA levels were measured using an ELISA, Western blots, and PCR. A neutralization study using an antibody against Gc protein was performed in an experimental asthma model.

MEASUREMENTS AND MAIN RESULTS

Based on 2DE, 15 proteins were significantly up-regulated or down-regulated in eight subjects with asthma compared with eight control subjects. The protein levels of Gc, hemopexin, and haptoglobin-b were increased, whereas the a1- antitrypsin and glutathione S-transferase levels were decreased in subjects with asthma. The Gc concentration in BAL fluid was significantly elevated in 67 subjects with asthma compared with that in 22 control subjects (P < 0.009). The Gc was significantly correlated with the neutrophil percentage in BAL fluid of subjects with asthma (P = 0.001). Gc mRNA and protein levels were higher in ovalbumin-sensitized/ challenged asthma mice than in sham-treated mice. Gc protein were expressed on alveolar macrophages and on epithelial cells. Treatment with an anti-Gc antibody dose-dependently reduced the ovalbumin sensitization/challenge-induced enhancement of airway hyperreactivity, airway inflammation, goblet cell hyperplasia,and levels of eotaxin, interleukin-4, -5, and -13, and interferon-g.

CONCLUSIONS

Gc may be involved in the development of asthma, and the neutralization of Gc protein could be a therapeutic strategy for asthma.

Proteomics in asthma and COPD phenotypes and endotypes for biomarker discovery and improved understanding of disease entities

The application of proteomics to respiratory diseases, such as asthma and COPD, has been limited compared to other fields, like cancer. Both asthma and COPD are recognised to be multi-factorial and complex diseases, both consisting of clusters of multiple disease phenotypes. The complexity of these diseases combined with the inaccessibility and invasiveness of disease relevant samples have provided a hurdle to the progress of respiratory proteomics. Advances in proteomic instrumentation and methodology have led to the possibility to identify proteomes in much smaller quantities of biological material. This review focuses on the efforts in respiratory proteomics in relation to asthma and COPD, and the importance of identifying subgroups of disease entities to establish appropriate biomarkers, and to enhance the understanding of underlying mechanisms in each subgroup. Careful phenotype characterisation of patient subpopulations is required to make improvement in the field of heterogeneous diseases such as asthma and COPD, and the clusters of phenotypes are likely to encompass subgroups of disease with distinct molecular mechanisms; endotypes. The utilisation of modern advanced proteomics in endotypes of asthma and COPD will likely contribute to the increased understanding of disease mechanisms, establishment of biomarkers for these endotypes and improved patient care.

Mucin granule-associated proteins in human bronchial epithelial cells: the airway goblet cell "granulome"

Background

Excess mucus in the airways leads to obstruction in diseases such as chronic bronchitis, asthma, and cystic fibrosis. Mucins, the highly glycosolated protein components of mucus, are stored in membrane-bound granules housed in the cytoplasm of airway epithelial "goblet" cells until they are secreted into the airway lumen via an exocytotic process. Precise mechanism(s) of mucin secretion, including the specific proteins involved in the process, have yet to be elucidated. Previously, we have shown that the Myristoylated Alanine-Rich C Kinase Substrate (MARCKS) protein regulates mucin secretion by orchestrating translocation of mucin granules from the cytosol to the plasma membrane, where the granules dock, fuse and release their contents into the airway lumen. Associated with MARCKS in this process are chaperone (Heat Shock Protein 70 [HSP70], Cysteine string protein [CSP]) and cytoskeletal (actin, myosin) proteins. However, additional granule-associated proteins that may be involved in secretion have not yet been elucidated.

Methods

Here, we isolated mucin granules and granule membranes from primary cultures of well differentiated human bronchial epithelial cells utilizing a novel technique of immuno-isolation, based on the presence of the calcium activated chloride channel hCLCA1 (the human ortholog of murine Gob-5) on the granule membranes, and verified via Western blotting and co-immunoprecipitation that MARCKS, HSP70, CSP and hCLCA1 were present on the granule membranes and associated with each other. We then subjected the isolated granules/membranes to liquid chromatography mass spectrometry (LC-MS/MS) to identify other granule associated proteins.

Results

A number of additional cytoskeletal (e.g. Myosin Vc) and regulatory proteins (e.g. Protein phosphatase 4) associated with the granules and could play a role in secretion were discovered. This is the first description of the airway goblet cell "granulome."

Application of proteomics in asthma research

Bronchial asthma is caused by allergic airway inflammation, resulting in reversible airway obstruction, characterized by airway hyper-responsiveness, bronchoconstriction, increased mucus secretion and an increase in lung vessel permeability. The pathophysiological changes in asthma have been attributed to the altered expression of biologically plausible proteins associated with transcriptional pathways, inflammatory mediators, chemokines, cytokines, apoptosis and cell proliferation. Such multifactorial diseases characteristically involve an interplay of many genetic variations of molecular and biochemical pathways and their interactions with environmental factors. The complex nature of the asthma phenotype, together with genetic heterogeneity and environmental influences, has made it difficult to uncover the aspects that underlie this common disease. Recently, genomic and proteomic technologies have been developed to identify associations between genes, proteins and disease. This approach, called 'omics biology', aims to recognize early onset of disease, institute preventive treatment and identify new molecular targets for novel drugs in multifactorial diseases. This article reviews examples of how proteomic technology can be used to find asthma marker proteins (from the cell model to clinical samples). Identification of protein changes in different stages of asthma could provide further insights into the complex molecular mechanisms involved in this disease. These studies provide new insights for finding novel pathological mediators and biomarkers of asthma.

Chronic lung diseases

Chronic lung diseases often have high morbidity and mortality rate and have posed a serious threat to human health. The incidence of many chronic lung diseases such as asthma has been on the rise in the past decade, which causes serious economic burden. Despite many efforts which employed traditional experimental approaches to elucidate the mechanisms of the diseases have been made, little is known about the pathogenesis of complex lung diseases. Systems biology approaches which aim to integrate and analyze information gathered from multiple sources offer a great opportunity to examine complex human diseases from a new angle. Many attempts have been made using high-throughput technologies such as microarrays to study chronic lung diseases; although compared with the full-fledged systems biology approach, research strategies employed in most of these investigations still have much room to improve, promising findings have already emerged from these efforts, which demonstrates the potential of implementing systems biology in pulmonary biomedical research.

Identification of toxicological biomarkers of di(2-ethylhexyl) phthalate in proteins secreted by HepG2 cells using proteomic analysis

The effects of di(2-ethylhexyl) phthalate (DEHP) on proteins secreted by HepG2 cells were studied using a proteomic approach. HepG2 cells were exposed to various concentrations of DEHP (0, 2.5, 5, 10, 25, 50, 100, and 250 microM) for 24 or 48 h. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and comet assays were then conducted to determine the cytotoxicity and genotoxicity of DEHP, respectively. The MTT assay showed that 10 microM DEHP was the maximum concentration that did not cause cell death. In addition, the DNA damage in HepG2 cells exposed to DEHP was found to increase in a dose- and time-dependent fashion. Proteomic analysis using two different pI ranges (4-7 and 6-9) and large size 2-DE revealed the presence of 2776 protein spots. A total of 35 (19 up- and 16 down-regulated) proteins were identified as biomarkers of DEHP by ESI-MS/MS. Several differentiated protein groups were also found. Proteins involved in apoptosis, transportation, signaling, energy metabolism, and cell structure and motility were found to be up- or down-regulated. Among these, the identities of cystatin C, Rho GDP inhibitor, retinol binding protein 4, gelsolin, DEK protein, Raf kinase inhibitory protein, triose phosphate isomerase, cofilin-1, and haptoglobin-related protein were confirmed by Western blot assay. Therefore, these proteins could be used as potential biomarkers of DEHP and human disease associated with DEHP.

Gelsolin restores A beta-induced alterations in choroid plexus epithelium

Histologically, Alzheimer's disease (AD) is characterized by senile plaques and cerebrovascular amyloid deposits. In previous studies we demonstrated that in AD patients, amyloid-β (Aβ) peptide also accumulates in choroid plexus, and that this process is associated with mitochondrial dysfunction and epithelial cell death. However, the molecular mechanisms underlying Aβ accumulation at the choroid plexus epithelium remain unclear. Aβ clearance, from the brain to the blood, involves Aβ carrier proteins that bind to megalin, including gelsolin, a protein produced specifically by the choroid plexus epithelial cells. In this study, we show that treatment with gelsolin reduces Aβ-induced cytoskeletal disruption of blood-cerebrospinal fluid (CSF) barrier at the choroid plexus. Additionally, our results demonstrate that gelsolin plays an important role in decreasing Aβ-induced cytotoxicity by inhibiting nitric oxide production and apoptotic mitochondrial changes. Taken together, these findings make gelsolin an appealing tool for the prophylactic treatment of AD.

Recent findings on the pathogenesis of bronchial asthma

In the first part of this series of papers (Székely and Pataki, 102) the pathogenesis of asthma was approached as a pathological antigen-antibody complex induced vago-vagal axon reflex. In the next part (103) the contribution of individual hormonal predisposition, the environmental and the most frequent allergizing factors have been reviewed. In the first section of this last (third) part of the review the genetic factors contributing to the asthma are surveyed. In this field a great progress has been made during the last decade, a lot of genes have been pinpointed which contribute to the heredity of the disease. In the second section of this last paper on the etiology of asthma an attempt is made to summarize the previously reviewed data and some new ones. Actually a new hypothesis is proposed that beyond the multitude of genetic, environmental and hormonal factors the underlying biochemical mechanism is simple: the disequilibrium of two functionally opposing second messenger systems in the airways: the Ca i ++ liberating PLC-PKC cascade and the Ca i ++ level reducing cAMP mediated one with preponderance of the former.

Biomarkers of lung-related diseases: current knowledge by proteomic approaches

The lung epithelial surface is one of the vital barriers or sensors in the body responding to the external atmosphere and thereby always subjecting to direct toxicological exposure, stress, stimulus, or infection. Due to its relatively higher sensitivity in response to toxicants, the use of lung epithelial cell culture and lung tissue from animal models or patients has facilitated our learning to lung physiopathology and toxicopharmacology. The recent advancement of proteomics has made it possible to investigate the cellular response at a global level. In this review, the potential applications of proteomic approach in studying lung-related diseases and biomarker discovery will be discussed.

Serum ferritin and transferrin levels as serologic markers of methylene diphenyl diisocyanate-induced occupational asthma

BACKGROUND

Although methylene diphenyl diisocyanate (MDI) may induce occupational asthma in the workplace, the pathogenic mechanisms are unclear.

OBJECTIVES

By using bronchoalveolar lavage fluid, we sought to identify proteins that were differentially expressed between subjects with MDI-induced occupational asthma (MDI-OA) and asymptomatic exposed controls (AECs).

METHODS

To find proteins that were differentially expressed between the MDI-OA and AEC groups, 2-dimensional electrophoresis was performed by using bronchoalveolar lavage fluid obtained from subjects after MDI-specific inhalation challenge. The selected protein spots were then identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The clinical relevance of the differentially expressed spots was compared by ELISA using sera from the MDI-OA/eosinophilic bronchitis, AEC, and unexposed healthy control groups. Receiver operating characteristic curves were then plotted, and the sensitivity and specificity were determined.

RESULTS

Twenty-three protein spots were identified that distinguished the subjects with MDI-OA from those in the AEC group. Among them, ferritin expression was downregulated whereas transferrin expression was upregulated in subjects with MDI-OA compared with AEC; these results were validated by ELISA using sera from the MDI-OA/EB and AEC groups. To identify subjects with MDI-OA, the optimal serum cutoff levels were 69.84 ng/mL for ferritin and 2.48 microg/mL for transferrin. When these 2 parameters were combined, the sensitivity was 71.43% and the specificity was 85.71%.

CONCLUSION

Serum ferritin and transferrin levels are associated with the phenotype of MDI-OA.

Staphylococcus aureus elicits marked alterations in the airway proteome during early pneumonia

Pneumonia caused by Staphylococcus aureus is a growing concern in the health care community. We hypothesized that characterization of the early innate immune response to bacteria in the lungs would provide insight into the mechanisms used by the host to protect itself from infection. An adult mouse model of Staphylococcus aureus pneumonia was utilized to define the early events in the innate immune response and to assess the changes in the airway proteome during the first 6 h of pneumonia. S. aureus actively replicated in the lungs of mice inoculated intranasally under anesthesia to cause significant morbidity and mortality. By 6 h postinoculation, the release of proinflammatory cytokines caused effective recruitment of neutrophils to the airway. Neutrophil influx, loss of alveolar architecture, and consolidated pneumonia were observed histologically 6 h postinoculation. Bronchoalveolar lavage fluids from mice inoculated with phosphate-buffered saline (PBS) or S. aureus were depleted of overabundant proteins and subjected to strong cation exchange fractionation followed by liquid chromatography and tandem mass spectrometry to identify the proteins present in the airway. No significant changes in response to PBS inoculation or 30 min following S. aureus inoculation were observed. However, a dramatic increase in extracellular proteins was observed 6 h postinoculation with S. aureus, with the increase dominated by inflammatory and coagulation proteins. The data presented here provide a comprehensive evaluation of the rapid and vigorous innate immune response mounted in the host airway during the earliest stages of S. aureus pneumonia.

Cysteinyl leukotriene receptor antagonist MK-571 alters bronchoalveolar lavage fluid proteome in a mouse asthma model

Cysteinyl leukotriene receptor type 1 (leukotriene CysLT(1) receptor) antagonist is one of the most effective anti-inflammatory agents for asthma. The spectrum of protein targets that can be regulated by leukotriene CysLT(1) receptor antagonist in asthma is not fully understood. The present study tried to identify novel protein targets of a selective leukotriene CysLT(1) receptor antagonist MK-571 in allergic airway inflammation by analyzing the proteome of mouse bronchoalveolar lavage fluid. BALB/c mice sensitized and challenged with ovalbumin showed increased pulmonary inflammatory cell infiltration, airway mucus production and serum ovalbumin-specific IgE level. MK-571 inhibited all these allergic airway inflammation endpoints. Lavage fluid proteins were resolved by two-dimensional gel electrophoresis and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The level of fourteen bronchoalveolar lavage fluid protein spots was markedly altered by MK-571. A family of chitinases (Ym1, Ym2 and acidic mammalian chitinase), lungkine, surfactant protein-D and gamma-actin have been found for the first time to be down-regulated by leukotriene CysLT(1) receptor antagonist in mouse allergic airways. Some of the down-regulatory effects were confirmed with reverse transcription-polymerase chain reaction analyses. Taken together, we have identified novel protein targets that can be regulated by leukotriene CysLT(1) receptor antagonist in mouse allergic airway inflammation, and our findings reveal additional pharmacological actions of leukotriene CysLT(1) receptor antagonist in the treatment of asthma.

Peripheral transgene expression of plasma gelsolin reduces amyloid in transgenic mouse models of Alzheimer's disease

The accumulation and deposition of the 40-42-amino acid peptide amyloid beta (Abeta) is thought to be a critical event in the pathology of Alzheimer's disease (AD). Both passive and active immunizations against Abeta in amyloid-depositing transgenic mice have reduced Abeta pathology and improved memory-related behavior. Peripheral treatments with other amyloid-binding agents have also reduced Abeta pathology. The present study demonstrates that peripheral delivery of plasmid DNA coding for the amyloid-binding protein plasma gelsolin reduces brain Abeta in two separate amyloid-depositing transgenic mouse models of AD when inter-litter variability is accounted for. The reduction in Abeta pathology observed is accompanied by an apparent increase in activated and reactive microglia and soluble oligomeric forms of amyloid. These findings demonstrate that peripheral expression of plasma gelsolin may be a suitable gene-therapeutic approach for the prevention or treatment of AD.

Proteomic analysis of the airway surface liquid: modulation by proinflammatory cytokines

The airway surface is covered by a fluid, the airway surface liquid, interposed between the mucous layer and the epithelium. The airway surface liquid contains proteins, secreted by different cell types, that may have pro-/anti-inflammatory or bactericidal functions or have a role in the mucociliary clearance. We have used a proteomics approach to identify the proteins secreted by an isolated in vitro model of human airway epithelium, at resting and under proinflammatory conditions, as a strategy to define the factors involved in epithelial barrier function. To this aim, we have analyzed the airway surface liquid from human bronchial epithelial cells grown as polarized monolayers in the presence and absence of inflammatory stimuli such as IL-4, IL-1β, TNF-α, and IFN-γ. Two-dimensional electrophoresis followed by mass spectrometry analysis has allowed the identification of ∼175 secreted protein spots, among which are immune-related proteins, structural proteins, an actin severer, some protease inhibitors, and a metalloproteinase. Comparisons between treated and untreated conditions have shown that the expression of several proteins was significantly modified by the different cytokines. Our results indicate that the surface epithelium is an active player in the epithelial barrier function and that inflammatory conditions may modulate protein secretion.

Human body fluid proteome analysis

The focus of this article is to review the recent advances in proteome analysis of human body fluids, including plasma/serum, urine, cerebrospinal fluid, saliva, bronchoalveolar lavage fluid, synovial fluid, nipple aspirate fluid, tear fluid, and amniotic fluid, as well as its applications to human disease biomarker discovery. We aim to summarize the proteomics technologies currently used for global identification and quantification of body fluid proteins, and elaborate the putative biomarkers discovered for a variety of human diseases through human body fluid proteome (HBFP) analysis. Some critical concerns and perspectives in this emerging field are also discussed. With the advances made in proteomics technologies, the impact of HBFP analysis in the search for clinically relevant disease biomarkers would be realized in the future.

Proteome analysis of bronchoalveolar lavage in lung diseases

The proteomic approach is complementary to genomics and enables protein composition to be investigated under various clinical conditions. Its application to the study of bronchoalveolar lavage (BAL) is extremely promising. BAL proteomic studies were initially based on two-dimensional electrophoretic separation of complex protein samples and subsequent identification of proteins by different methods. With the techniques available today it is possible to attain many different research objectives. BAL proteomics can contribute to the identification of proteins in alveolar spaces with possible insights into pathogenesis and clinical application for diagnosis, prognosis and therapy. Many proteins with different functions have already been identified in BAL. Some could be biomarkers that need to be individually confirmed by correlation with clinical parameters and validation by other methods on larger cohorts of patients. The standardization of BAL sample preparation and processing for proteomic studies is an important goal that would promote and facilitate clinical applications. Here, we review the principal literature on BAL proteomic analysis applied to the study of lung diseases.

Dexamethasone alters bronchoalveolar lavage fluid proteome in a mouse asthma model

BACKGROUND

Glucocorticoid is the most effective anti-inflammatory agent for asthma. The spectrum of protein targets that can be regulated by glucocorticoid in asthma is not fully understood. The present study tried to identify novel protein targets of dexamethasone in allergic airway inflammation by analyzing the proteome of mouse bronchoalveolar lavage (BAL) fluid.

METHODS

BALB/c mice sensitized and challenged with ovalbumin (OVA) showed increased pulmonary inflammatory cell infiltration, airway mucus production and serum OVA-specific IgE level. Dexamethasone inhibited all these allergic airway inflammation endpoints. BAL fluid proteins were resolved by two-dimensional gel electrophoresis and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

The levels of 26 BAL fluid proteins were found to be markedly altered by dexamethasone. A family of chitinases (Ym1, Ym2 and acidic mammalian chitinase, AMCase), lungkine, gob-5, surfactant protein D and polymeric immunoglobulin receptor have been found for the first time to be downregulated by dexamethasone in allergic airways. The downregulatory effects were confirmed by immunoblotting and RT-PCR analyses. Dexamethasone was also shown to significantly inhibit lavage fluid chitinase bioactivity. In addition, dexamethasone promoted airway expression of vitamin D-binding protein, heptoglobin and alpha(1)-antitrypsin.

CONCLUSIONS

Among all these newly identified protein targets of dexamethasone, AMCase and gob-5 have been shown to be pro-inflammatory in asthma. Downregulation of AMCase and gob-5 may be considered as two novel anti-inflammatory actions of glucocorticoid in asthma.

Cystic fibrosis enters the proteomics scene: New answers to old questions

The discovery in 1989 of the gene encoding for the cystic fibrosis transmembrane conductance regulator (CFTR) and its mutation as the primary cause of cystic fibrosis (CF), generated an optimistic reaction with respect to the development of potential therapies. This extraordinary milestone, however, represented only the initial key step in a long path. Many of the mechanisms that govern the pathogenesis of CF, the most commonly inherited lethal pulmonary disorder in Caucasians, remain even today unknown. As a continuation to genomic research, proteomics now offers the unique advantage to examine global alterations in the protein expression patterns of CF cells and tissues. The systematic use of this approach will probably provide new insights into the cellular mechanisms involved in CF dysfunctions, and should ultimately result in the finding of new prognostic markers, and in the generation of new therapies. In this article we review the current status of proteomic research applied to the study of CF, including CFTR-related interactomics, and evaluate the potential of these technologies for future investigations.

Gelsolin secretion in interleukin-4-treated bronchial epithelia and in asthmatic airways

RATIONALE

The airway surface liquid, the thin layer of liquid covering the airways, is essential for mucociliary clearance and as a barrier against microbial and other noxious agents. Proteins secreted into the airway surface liquid by epithelial and nonepithelial cells may be important in innate immunity and to improve the fluidity of mucous secretions.

OBJECTIVES

We aimed to identify proteins specifically secreted into the airway surface liquid by human bronchial epithelial cells, in resting conditions and after treatment with interleukin 4 (IL-4), a cytokine released in asthma.

METHODS AND MAIN RESULTS

By using a proteomics approach, we found that one of the most abundant proteins was gelsolin, which breaks down actin filaments. Gelsolin mRNA and protein secretion were increased threefold in the airway surface liquid of epithelia treated with IL-4. These results were confirmed at the functional level by measuring actin depolymerization using a fluorescence assay. Gelsolin protein was also upregulated in the airways of subjects with asthma.

CONCLUSIONS

Our findings indicate that gelsolin is released by epithelial cells into the airways and that its secretion is increased by IL-4 in vitro. In addition, we found that the concentration of both IL-4 and gelsolin were raised in the bronchoalveolar lavage of patients with asthma. These results suggest that gelsolin might improve the fluidity of airway surface liquid in asthma by breaking down filamentous actin that may be released in large amounts by dying cells during inflammation.