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Mönki J, Mykkänen A. Lipids in Equine Airway Inflammation: An Overview of Current Knowledge. Animals (Basel) 2024; 14:1812. [PMID: 38929431 PMCID: PMC11200544 DOI: 10.3390/ani14121812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 06/08/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024] Open
Abstract
Mild-moderate and severe equine asthma (MEA and SEA) are prevalent inflammatory airway conditions affecting horses of numerous breeds and disciplines. Despite extensive research, detailed disease pathophysiology and the differences between MEA and SEA are still not completely understood. Bronchoalveolar lavage fluid cytology, broadly used in clinical practice and in equine asthma research, has limited means to represent the inflammatory status in the lower airways. Lipidomics is a field of science that can be utilized in investigating cellular mechanisms and cell-to-cell interactions. Studies in lipidomics have a broad variety of foci, of which fatty acid and lipid mediator profile analyses and global lipidomics have been implemented in veterinary medicine. As many crucial proinflammatory and proresolving mediators are lipids, lipidomic studies offer an interesting yet largely unexplored means to investigate inflammatory reactions in equine airways. The aim of this review article is to collect and summarize the findings of recent lipidomic studies on equine airway inflammation.
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Affiliation(s)
| | - Anna Mykkänen
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Viikintie 49, P.O. Box 57, 00014 Helsinki, Finland;
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The Combination of Bioinformatics Analysis and Untargeted Metabolomics Reveals Potential Biomarkers and Key Metabolic Pathways in Asthma. Metabolites 2022; 13:metabo13010025. [PMID: 36676950 PMCID: PMC9860906 DOI: 10.3390/metabo13010025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 12/14/2022] [Accepted: 12/19/2022] [Indexed: 12/28/2022] Open
Abstract
Asthma is a complex chronic airway inflammatory disease that seriously impacts patients' quality of life. As a novel approach to exploring the pathogenesis of diseases, metabolomics provides the potential to identify biomarkers of asthma host susceptibility and elucidate biological pathways. The aim of this study was to screen potential biomarkers and biological pathways so as to provide possible pharmacological therapeutic targets for asthma. In the present study, we merged the differentially expressed genes (DEGs) of asthma in the GEO database with the metabolic genes obtained by Genecard for bioinformatics analysis and successfully screened out the metabolism-related hub genes (HIF1A, OCRL, NNMT, and PER1). Then, untargeted metabolic techniques were utilized to reveal HDM-induced metabolite alterations in 16HBE cells. A total of 45 significant differential metabolites and 5 differential metabolic pathways between the control group and HDM group were identified based on the OPLS-DA model. Finally, three key metabolic pathways, including glycerophospholipid metabolism, galactose metabolism, and alanine, aspartate, and glutamate metabolism, were screened through the integrated analysis of bioinformatics data and untargeted metabolomics data. Taken together, these findings provide valuable insights into the pathophysiology and targeted therapy of asthma and lay a foundation for further research.
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Albornoz A, Alarcon P, Morales N, Uberti B, Henriquez C, Manosalva C, Burgos RA, Moran G. Metabolomics analysis of bronchoalveolar lavage fluid samples in horses with naturally-occurring asthma and experimentally-induced airway inflammation. Res Vet Sci 2020; 133:276-282. [PMID: 33039879 DOI: 10.1016/j.rvsc.2020.09.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 09/22/2020] [Accepted: 09/28/2020] [Indexed: 01/09/2023]
Abstract
The present work characterized the metabolomic profile of bronchoalveolar lavage fluid (BALF) in healthy horses, experimentally-induced airway inflammation by lipopolysaccharide (LPS) nebulization, and naturally-occurring asthma (n = 3 in each group). All animals underwent clinical and upper airway endoscopic examinations, and bronchoalveolar lavage. BALF supernatant samples were subjected to metabolic analysis based on gas chromatography-mass spectrometry (GC-MS). Overall, 67 peaks were obtained from BALF GC-MS analysis, corresponding to 53 metabolites which were categorized according to chemical class, such as organic acids, fatty acids, nucleosides or their derivatives, amino acids, peptides or their derivatives, carbohydrates, and other compounds. Our results showed that the airway inflammation induction model with LPS produced the same pattern of metabolite changes as in horses with naturally occurring asthma. Metabolic pathway analysis was done by means of Fisher's exact test, for detection of metabolites over-represented in asthma affected-horses and LPS-induced airway inflammation as compared with healthy horses. The most significant altered metabolic pathways were fatty acid biosynthesis, galactose metabolism and citrate cycle. These results suggest that the airway inflammation induction model with LPS is a good study model for asthma-affected horses, due to the similarity of the profile of inflammatory cells (specifically neutrophils) and similar metabolic alterations found in BALF that occur during the inflammatory process of the airways. Further research may increase understanding of metabolomics disturbances and their significance in the pathogenesis of equine asthma.
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Affiliation(s)
- Alejandro Albornoz
- Department of Pharmacology, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Pablo Alarcon
- Department of Pharmacology, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Natalia Morales
- Department of Pharmacology, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Benjamin Uberti
- Department of Clinical Veterinary Sciences, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Claudio Henriquez
- Department of Pharmacology, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Carolina Manosalva
- Department of Pharmacy, Faculty of Science, Universidad Austral de Chile, Valdivia, Chile
| | - Rafael A Burgos
- Department of Pharmacology, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Gabriel Moran
- Department of Pharmacology, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile.
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Nesterov YV. An Experiment on Age-Related Characteristics of the Reaction of Lung Tissue and Surfactant to Hypobaric Hypoxia and Hyperbaric Hyperoxia. ADVANCES IN GERONTOLOGY 2020. [DOI: 10.1134/s2079057020030121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Bazzano M, Laghi L, Zhu C, Magi GE, Serri E, Spaterna A, Tesei B, Laus F. Metabolomics of tracheal wash samples and exhaled breath condensates in healthy horses and horses affected by equine asthma. J Breath Res 2018; 12:046015. [PMID: 30168442 DOI: 10.1088/1752-7163/aade13] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The present work characterized the metabolomic profile of tracheal wash (TW) and exhaled breath condensate (EBC) in healthy horses and horses with respiratory disease. Six asthma-affected horses (group A) and six healthy controls (group H) underwent clinical, endoscopic and cytologic examinations of upper airways to confirm the active phase of asthma. TW and EBC samples were collected from each animal and investigated by proton nuclear magnetic resonance (1H-NMR) metabolomic analysis. A total of ten out of 38 metabolites found in the TW were significantly different between the groups (p < 0.05). Higher concentrations of histamine and oxidant agents, such as glutamate, valine, leucine and isoleucine, as well as lower levels of ascorbate, methylamine, dimethylamine and O-phosphocholine, were found in group A compared to group H. Eight metabolites were found in equine EBC, namely methanol, ethanol, formate, trimethylamine, acetone, acetate, lactate and butanone, previously observed also in human EBC. Despite the fact that this was a pilot study, the results showed that the metabolomic analysis of TW and EBC has the potentiality to serve as a basis for diagnostic tools in horses with asthma.
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Affiliation(s)
- Marilena Bazzano
- School of Biosciences and Veterinary Medicine, University of Camerino, Macerata, Italy
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Chronic features of allergic asthma are enhanced in the absence of resistin-like molecule-beta. Sci Rep 2018; 8:7061. [PMID: 29728628 PMCID: PMC5935686 DOI: 10.1038/s41598-018-25321-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/19/2018] [Indexed: 02/07/2023] Open
Abstract
Asthma is characterized by inflammation and architectural changes in the lungs. A number of immune cells and mediators are recognized as initiators of asthma, although therapeutics based on these are not always effective. The multifaceted nature of this syndrome necessitate continued exploration of immunomodulators that may play a role in pathogenesis. We investigated the role of resistin-like molecule-beta (RELM-β), a gut antibacterial, in the development and pathogenesis of Aspergillus-induced allergic airways disease. Age and gender matched C57BL/6J and Retnlb−/− mice rendered allergic to Aspergillus fumigatus were used to measure canonical markers of allergic asthma at early and late time points. Inflammatory cells in airways were similar, although Retnlb−/− mice had reduced tissue inflammation. The absence of RELM-β elevated serum IgA and pro-inflammatory cytokines in the lungs at homeostasis. Markers of chronic disease including goblet cell numbers, Muc genes, airway wall remodelling, and hyperresponsiveness were greater in the absence RELM-β. Specific inflammatory mediators important in antimicrobial defence in allergic asthma were also increased in the absence of RELM-β. These data suggest that while characteristics of allergic asthma develop in the absence of RELM-β, that RELM-β may reduce the development of chronic markers of allergic airways disease.
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Nobakht M Gh BF, Aliannejad R, Rezaei-Tavirani M, Taheri S, Oskouie AA. The metabolomics of airway diseases, including COPD, asthma and cystic fibrosis. Biomarkers 2014; 20:5-16. [PMID: 25403491 DOI: 10.3109/1354750x.2014.983167] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Chronic obstructive pulmonary disease (COPD), asthma and cystic fibrosis (CF) are characterized by airway obstruction and an inflammatory process. Reaching early diagnosis and discrimination of subtypes of these respiratory diseases are quite a challenging task than other chronic illnesses. Metabolomics is the study of metabolic pathways and the measurement of unique biochemical molecules generated in a living system. In the last decade, metabolomics has already proved to be useful for the characterization of several pathological conditions and offers promises as a clinical tool. In this article, we review the current state of the metabolomics of COPD, asthma and CF with a focus on the different methods and instrumentation being used for the discovery of biomarkers in research and translation into clinic as diagnostic aids for the choice of patient-specific therapies.
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Affiliation(s)
- B Fatemeh Nobakht M Gh
- Faculty of Paramedical Sciences, Proteomics Research Center, Shahid Beheshti University of Medical Sciences , Tehran , Iran
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Jung J, Kim SH, Lee HS, Choi GS, Jung YS, Ryu DH, Park HS, Hwang GS. Serum metabolomics reveals pathways and biomarkers associated with asthma pathogenesis. Clin Exp Allergy 2013; 43:425-33. [PMID: 23517038 DOI: 10.1111/cea.12089] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 12/03/2012] [Accepted: 12/05/2012] [Indexed: 12/31/2022]
Abstract
BACKGROUND Asthma is a chronic inflammatory disease caused by complex interactions of genetic, epigenetic, and environmental factors. For this reason, new approaches are required to clarify the pathogenesis of asthma by systemic review. OBJECTIVE We applied a (1)H-NMR metabolomics approach to investigate the altered metabolic pattern in sera from patients with asthma and sought to identify the mechanism underlying asthma and potential biomarkers. METHOD A global profile of sera from patients with asthma (n = 39) and controls (n = 26) was generated using (1)H-NMR spectroscopy coupled with multivariate statistical analysis. Endogenous metabolites in serum were rapidly measured using the target-profiling procedure. RESULTS Multivariate statistical analysis showed a clear distinction between patients with asthma and healthy subjects. Sera of asthma patients were characterized by increased levels of methionine, glutamine, and histidine and by decreased levels of formate, methanol, acetate, choline, O-phosphocholine, arginine, and glucose. The metabolites detected in the sera of patients with asthma are involved in hypermethylation, response to hypoxia, and immune reaction. Furthermore, the levels of serum metabolites from patients with asthma correlated with asthma severity; in particular, lipid metabolism was altered in patients with lower forced expiratory volume in 1 s percentage (FEV(1)%) predicted values. In addition, potential biomarkers showed strong predictive power in ROC analysis, and the presence of asthma in external validation models was predicted with high accuracy (90.9% for asthma and 100% for control subjects). CONCLUSION & CLINICAL RELEVANCE These data showed that (1)H-NMR-based metabolite profiling of serum may be useful for the effective diagnosis of asthma and a further understanding of its pathogenesis.
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Affiliation(s)
- J Jung
- Integrated Metabolomics Research Group, Seoul Center, Korea Basic Science Institute, Seoul, Republic of Korea
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Molecular and Physiological Determinants of Pulmonary Developmental Biology: a Review. ACTA ACUST UNITED AC 2013. [DOI: 10.12691/ajbr-1-1-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Tavana H, Huh D, Grotberg JB, Takayama S. Microfluidics, Lung Surfactant, and Respiratory Disorders. Lab Med 2009. [DOI: 10.1309/lmjwe0wo65vfwpas] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Christmann U, Buechner-Maxwell VA, Witonsky SG, Hite RD. Role of lung surfactant in respiratory disease: current knowledge in large animal medicine. J Vet Intern Med 2009; 23:227-42. [PMID: 19192153 DOI: 10.1111/j.1939-1676.2008.0269.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Lung surfactant is produced by type II alveolar cells as a mixture of phospholipids, surfactant proteins, and neutral lipids. Surfactant lowers alveolar surface tension and is crucial for the prevention of alveolar collapse. In addition, surfactant contributes to smaller airway patency and improves mucociliary clearance. Surfactant-specific proteins are part of the innate immune defense mechanisms of the lung. Lung surfactant alterations have been described in a number of respiratory diseases. Surfactant deficiency (quantitative deficit of surfactant) in premature animals causes neonatal respiratory distress syndrome. Surfactant dysfunction (qualitative changes in surfactant) has been implicated in the pathophysiology of acute respiratory distress syndrome and asthma. Analysis of surfactant from amniotic fluid allows assessment of fetal lung maturity (FLM) in the human fetus and exogenous surfactant replacement therapy is part of the standard care in premature human infants. In contrast to human medicine, use and success of FLM testing or surfactant replacement therapy remain limited in veterinary medicine. Lung surfactant has been studied in large animal models of human disease. However, only a few reports exist on lung surfactant alterations in naturally occurring respiratory disease in large animals. This article gives a general review on the role of lung surfactant in respiratory disease followed by an overview of our current knowledge on surfactant in large animal veterinary medicine.
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Affiliation(s)
- U Christmann
- Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Duck Pond Drive, Phase II, Blacksburg, VA 24061, USA.
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Abstract
In this article, the physiology of surfactant is reviewed along with the research that lead to its current clinical uses. Acute lung injury (ALI) and Acute Respiratory Distress Syndrome (ARDS) will also be reviewed because they represent pulmonary disease processes in which secondary deficiency and surfactant inactivation occur, for which surfactant may prove to be an effective treatment. Finally, research using surfactant as a treatment for other pulmonary diseases, such as bronchiolitis and asthma, will be briefly highlighted. These studies may one day lead to new treatment opportunities in the realm of emergency medicine.
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Abstract
Beta(2)-adrenergic agonists cause a release of pulmonary surfactant into lung airways. The surfactant phospholipids maintain the patency of the conducting airways, but this function is inhibited by plasma proteins entering an inflamed airway. The physical behavior of the surfactant can be studied with a pulsating bubble surfactometer and a capillary surfactometer. Calf lung surfactant extract was found to be inhibited by plasma proteins and by a lowering of temperature. Severe breathing difficulties and malfunctioning surfactant developed in BALB/c mice inhaling ozone or infected with respiratory syncytial virus, mainly as a result of proteins invading the airways. Patients with asthma were challenged with allergens in an area of one lung. BAL fluid (BALF) from such an area contained a surfactant that functioned poorly (ie, an inability to maintain airway openness) compared with BALF from the other lung or from the lungs of healthy volunteers. When proteins in the BALF were removed, surfactant performance clearly improved. Eosinophils, so prominent in asthmatic patients, synthesize the enzyme lysophospholipase, which, together with the enzyme phospholipase A(2), catalyzes the hydrolysis of the main component of the surfactant, phosphatidylcholine. Such hydrolysis incapacitates the ability of the surfactant to maintain airway patency. The treatment of asthma with beta(2)-adrenergic agonists and steroids will have a valuable effect on the surfactant system. It will cause a release of fresh surfactant into terminal airways. Surfactant can also be nebulized and inhaled, which has been shown to be an effective treatment.
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Affiliation(s)
- Goran Enhorning
- SUNY at Buffalo, Department of Gynecology/Obstetrics, NY 14222, USA.
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Kendall M. Fine airborne urban particles (PM2.5) sequester lung surfactant and amino acids from human lung lavage. Am J Physiol Lung Cell Mol Physiol 2007; 293:L1053-8. [PMID: 17616648 DOI: 10.1152/ajplung.00131.2007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Components of surfactant act as opsonins and enhance phagocytosis of bacteria; whether this process occurs with atmospheric fine particles has not been shown. We have studied the interactions of fine particles (urban PM2.5) and surfactant removed from normal human lungs by lavage, using a surface analysis technique. The aim was to identify which of the chemical components of brochoalveolar lavage (BAL) deposit on the surfaces of urban PM2.5. Deposition of surfactant components on urban PM2.5 surfaces was reported in previous studies, but molecular identification and relative quantification was not possible using simple data analysis. In this study, we were able to identify adsorbed components by applying an appropriate statistical technique, factor analysis. In this study, the most strongly associated mass fragment on PM2.5 surfaces exposed to BAL (and undetected on both untreated samples and saline controls) was di-palmitoyl-phosphatidylcholine, a component of lung surfactant. Amino acids were also strongly associated with BAL-exposed PM2.5 surfaces and not other sample types. Thirteen mass fragments were identified, diagnostic of the amino acids alanine, arginine, asparagine, aspartic acid, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, serine, and valine. This study provides evidence that lung surfactant and amino acids related to opsonin proteins adsorb to nonbiological particle surfaces exposed to human lung lining fluid. Disruption of normal surfactant function, both physical and immunological, is possible but unproven. Further work on this PM-opsonin interaction is recommended.
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Kwatia MA, Doyle CB, Cho W, Enhorning G, Ackerman SJ. Combined activities of secretory phospholipases and eosinophil lysophospholipases induce pulmonary surfactant dysfunction by phospholipid hydrolysis. J Allergy Clin Immunol 2007; 119:838-47. [PMID: 17321580 DOI: 10.1016/j.jaci.2006.12.614] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 11/29/2006] [Accepted: 12/11/2006] [Indexed: 10/23/2022]
Abstract
BACKGROUND Surfactant dysfunction is implicated in small airway closure in asthma. Increased activity of secretory phospholipase A(2) (sPLA(2)) in the airways is associated with asthma exacerbations. Phosphatidylcholine, the principal component of pulmonary surfactant that maintains small airway patency, is hydrolyzed by sPLA(2). The lysophosphatidylcholine product is the substrate for eosinophil lysophospholipases. OBJECTIVE To determine whether surfactant phospholipid hydrolysis by the combined activities of sPLA(2)s and eosinophil lysophospholipases induces surfactant dysfunction. METHODS The effect of these enzymes on surfactant function was determined by capillary surfactometry. Thin layer chromatography was used to correlate enzyme-induced changes in surfactant phospholipid composition and function. Phosphatidylcholine and its hydrolytic products were measured by using mass spectrometry. RESULTS Eosinophils express a 25-kd lysophospholipase and group IIA sPLA(2). Phospholipase A(2) alone induced only a small decrease in surfactant function, and 25-kd lysophospholipase alone degraded lysophosphatidylcholine but had no effect on surfactant function. The combined actions of sPLA(2) and lysophospholipase produced dose-dependent and time-dependent losses of surfactant function, concomitant with hydrolysis of phosphatidylcholine and lysophosphatidylcholine. Lysates of AML14.3D10 eosinophils induced surfactant dysfunction, indicating these cells express all the necessary lipolytic activities. In contrast, lysates of blood eosinophils required exogenous phospholipase A(2) to induce maximal surfactant dysfunction. CONCLUSION The combined activities of sPLA(2)s and eosinophil lysophospholipases are necessary to degrade surfactant phospholipids sufficiently to induce functional losses in surfactant activity as reported in asthma. CLINICAL IMPLICATIONS The phospholipases and lysophospholipases expressed by eosinophils or other airway cells may represent novel therapeutic targets for blocking surfactant degradation, dysfunction, and peripheral airway closure in asthma.
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Affiliation(s)
- Mark A Kwatia
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607-7170, USA
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Koetzler R, Saifeddine M, Yu Z, Schürch FS, Hollenberg MD, Green FHY. Surfactant as an airway smooth muscle relaxant. Am J Respir Cell Mol Biol 2006; 34:609-15. [PMID: 16415252 DOI: 10.1165/rcmb.2005-0228oc] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A variety of clinical and experimental evidence indicates that surfactant may be important in the pathogenesis and treatment of asthma. The purpose of this study was to determine the pharmacologic effect of pulmonary surfactant and its major lipid and protein constituents on bronchial smooth muscle. First-generation bronchi from male Sprague-Dawley rats were contracted with methacholine and exposed to two kinds of surfactant: whole rat surfactant and two bovine surfactant extracts in clinical use. The latter lack the hydrophilic surfactant-associated proteins (SP)-A and SP-D. All the surfactants relaxed the rat bronchi in a concentration-dependent manner; however, whole rat surfactant was more potent than the bovine extracts. Both surfactant lipids and SP-A contributed to the bronchial relaxation. The relaxation response produced by the highest concentration (0.5 mg/ml) of whole rat surfactant was equivalent to that caused by substance P (5 microM) and approximately half of that caused by 1 microM isoproterenol. The relaxation response was epithelium-dependent and blocked by indomethacin but not by N-omega-nitro-L-arginine methyl ester. We conclude that surfactant can relax airway smooth muscle directly via a prostanoid-mediated, epithelium-dependent process that does not involve nitric oxide synthase.
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Affiliation(s)
- Rommy Koetzler
- Department of Pathology & Laboratory Medicine, Faculty of Medicine, University of Calgary, 3330 Hospital Drive N.W., Calgary, AB T2N 4N1 Canada
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