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Frontiers in Immunology 2021Pulmonary surfactant is a complex and highly surface-active material. It covers the alveolar epithelium and consists of 90% lipids and 10% proteins. Pulmonary surfactant... (Review)
Review
Pulmonary surfactant is a complex and highly surface-active material. It covers the alveolar epithelium and consists of 90% lipids and 10% proteins. Pulmonary surfactant lipids together with pulmonary surfactant proteins facilitate breathing by reducing surface tension of the air-water interface within the lungs, thereby preventing alveolar collapse and the mechanical work required to breathe. Moreover, pulmonary surfactant lipids, such as phosphatidylglycerol and phosphatidylinositol, and pulmonary surfactant proteins, such as surfactant protein A and D, participate in the pulmonary host defense and modify immune responses. Emerging data have shown that pulmonary surfactant lipids modulate the inflammatory response and antiviral effects in some respiratory viral infections, and pulmonary surfactant lipids have shown promise for therapeutic applications in some respiratory viral infections. Here, we briefly review the composition, antiviral properties, and potential therapeutic applications of pulmonary surfactant lipids in respiratory viral infections.
Topics: Animals; Antiviral Agents; COVID-19; Host-Pathogen Interactions; Humans; Lipids; Lung; Pulmonary Surfactants; SARS-CoV-2; COVID-19 Drug Treatment
PubMed: 34646269
DOI: 10.3389/fimmu.2021.730022 -
Biochimica Et Biophysica Acta Nov 1998This review briefly notes recent findings important for understanding the surface mechanical functions of pulmonary surfactant. Currently known surfactant-specific... (Review)
Review
This review briefly notes recent findings important for understanding the surface mechanical functions of pulmonary surfactant. Currently known surfactant-specific proteins and lipids are discussed, with an eye to their possible functions. Competing models of the alveolar subphase life cycle of surfactant are also presented. It is concluded that, in spite of much effort, we still do not understand the basic molecular mechanisms underlying surfactant's rapid adsorption to the air-water interface.
Topics: Animals; Lipids; Models, Biological; Proteins; Pulmonary Alveoli; Pulmonary Surfactants; Rabbits; Sheep
PubMed: 9813251
DOI: 10.1016/s0925-4439(98)00060-x -
The Cochrane Database of Systematic... Jan 2010Respiratory distress syndrome (RDS) is caused by a deficiency or dysfunction of pulmonary surfactant. A variety of surfactant products including protein free synthetic... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Respiratory distress syndrome (RDS) is caused by a deficiency or dysfunction of pulmonary surfactant. A variety of surfactant products including protein free synthetic surfactant have been developed and tested in the prevention and treatment of RDS.
OBJECTIVES
To assess the effect of prophylactic administration of protein free synthetic surfactant (SS) on mortality, chronic lung disease and other morbidities associated with prematurity in preterm newborns at risk for developing RDS. Subgroup analysis were planned according to the degree of prematurity, surfactant product and dosage schedule.
SEARCH STRATEGY
Searches were made of the The Cochrane Library, MEDLINE, OVID, EMBASE, CINAHL from 1966 to 2009. In addition, previous reviews including cross references and abstracts from the Society for Pediatric Research were searched. No language restrictions were applied.
SELECTION CRITERIA
Randomized and quasi-randomized controlled trials that compared the effect of protein free SS administered to high risk preterm newborns at or shortly after birth in order to prevent RDS, mortality and complications of prematurity.
DATA COLLECTION AND ANALYSIS
Data regarding clinical outcomes was excerpted from the clinical trials by the reviewers. Data were analyzed according to the standards of the Cochrane Neonatal Review Group.
MAIN RESULTS
Studies of prophylactic administration of protein free SS note a variable improvement in the respiratory status and a decrease in respiratory distress syndrome in infants who receive prophylactic protein free SS. The meta-analysis supports a decrease in the risk of pneumothorax (typical relative risk 0.67, 95% CI 0.50, 0.90), pulmonary interstitial emphysema (typical relative risk 0.68, 95% CI 0.50, 0.93), and neonatal mortality (typical relative risk 0.70, 95% CI 0.58, 0.85). No differences were seen in the risk of intraventricular hemorrhage, necrotizing enterocolitis, bronchopulmonary dysplasia, retinopathy of prematurity and cerebral palsy. The meta-analysis supports an increase in the risk of patent ductus arteriosus associated with prophylactic SS administration (typical relative risk 1.11, 95% CI 1.00, 1.22), and an increase in the risk of pulmonary hemorrhage (typical relative risk 3.28, 95% CI 1.50, 7.16).
AUTHORS' CONCLUSIONS
Prophylactic intratracheal administration of protein free synthetic surfactant to infants at risk of developing respiratory distress syndrome has been demonstrated to improve clinical outcome. Infants who receive prophylactic protein free SS have a decreased risk of pneumothorax, a decreased risk of pulmonary interstitial emphysema, and a decreased risk of neonatal mortality. Infants who receive prophylactic protein free SS have an increased risk of developing patent ductus arteriosus and pulmonary hemorrhage.
Topics: Humans; Infant, Newborn; Infant, Premature; Infant, Premature, Diseases; Pulmonary Surfactants; Respiratory Distress Syndrome, Newborn
PubMed: 20091513
DOI: 10.1002/14651858.CD001079.pub2 -
The European Respiratory Journal Jun 1999Pulmonary surfactant is a complex and highly surface active material composed of lipids and proteins which is found in the fluid lining the alveolar surface of the... (Review)
Review
Pulmonary surfactant is a complex and highly surface active material composed of lipids and proteins which is found in the fluid lining the alveolar surface of the lungs. Surfactant prevents alveolar collapse at low lung volume, and preserves bronchiolar patency during normal and forced respiration (biophysical functions). In addition, it is involved in the protection of the lungs from injuries and infections caused by inhaled particles and micro-organisms (immunological, non-biophysical functions). Pulmonary surfactant can only be harvested by lavage procedures, which may disrupt its pre-existing biophysical and biochemical micro-organization. These limitations must always be considered when interpreting ex vivo studies of pulmonary surfactant. A pathophysiological role for surfactant was first appreciated in premature infants with respiratory distress syndrome and hyaline membrane disease, a condition which is nowadays routinely treated with exogenous surfactant replacement. Biochemical surfactant abnormalities of varying degrees have been described in obstructive lung diseases (asthma, bronchiolitis, chronic obstructive pulmonary disease, and following lung transplantation), infectious and suppurative lung diseases (cystic fibrosis, pneumonia, and human immunodeficiency virus), adult respiratory distress syndrome, pulmonary oedema, other diseases specific to infants (chronic lung disease of prematurity, and surfactant protein-B deficiency), interstitial lung diseases (sarcoidosis, idiopathic pulmonary fibrosis, and hypersensitivity pneumonitis), pulmonary alveolar proteinosis, following cardiopulmonary bypass, and in smokers. For some pulmonary conditions surfactant replacement therapy is on the horizon, but for the majority much more needs to be learnt about the pathophysiological role the observed surfactant abnormalities may have.
Topics: Humans; Lung; Lung Diseases; Pulmonary Surfactants
PubMed: 10445627
DOI: 10.1183/09031936.99.13614779 -
European Journal of Biochemistry Mar 1997The dominating functional property of pulmonary surfactant is to reduce the surface tension at the alveolar air/liquid interface, and thereby prevent the lungs from... (Review)
Review
The dominating functional property of pulmonary surfactant is to reduce the surface tension at the alveolar air/liquid interface, and thereby prevent the lungs from collapsing at the end of expiration. In addition, the system exhibits host-defense properties. Insufficient amounts of pulmonary surfactant in premature infants causes respiratory distress syndrome, a serious threat which nowadays can be effectively treated by airway instillation of surfactant preparations. Surfactant is a mixture of many molecular species, mainly phospholipids and specific proteins, surfactant protein A (SP-A), SP-B, SP-C and SP-D. SP-A and SP-D are water-soluble and belong to the collectins, a family of large multimeric proteins which structurally exhibit collagenous/lectin hybrid properties and functionally are Ca2+-dependent carbohydrate binding proteins involved in innate host-defence functions. SP-A and SP-D also bind lipids and SP-A is involved in organization of alveolar surfactant phospholipids. SP-B belongs to another family of proteins, which includes also lipid-interacting polypeptides with antibacterial and lytic properties. SP-B is a 17.4-kDa homodimer and each subunit contains three intrachain disulphides and has been proposed to contain four amphipathic helices oriented pairwise in an antiparallel fashion. SP-A, SP-B and SP-D all have been detected also in the gastrointestinal tract. SP-C, in contrast, appears to be a unique protein with extreme structural and stability properties and to exist exclusively in the lungs. SP-C is a lipopeptide containing covalently linked palmitoyl chains and is folded into a 3.7-nm alpha-helix with a central 2.3-nm all-aliphatic part, making it perfectly suited to interact in a transmembranous way with a fluid bilayer composed of dipalmitoylglycerophosphocholine, the main component of surfactant. Homozygous genetic deficiency of proSP-B causes lethal respiratory distress soon after birth and is associated with aberrant processing of the precursor of SP-C. This review focuses on the chemical composition, structures and interactions of the pulmonary surfactant, in particular the associated proteins.
Topics: Animals; Humans; Models, Molecular; Molecular Structure; Protein Conformation; Protein Processing, Post-Translational; Pulmonary Alveoli; Pulmonary Surfactants; Thermodynamics
PubMed: 9108235
DOI: 10.1111/j.1432-1033.1997.00675.x -
The Journal of Clinical Investigation Jul 1990
Review
Topics: Animals; Apoproteins; Humans; Proteolipids; Pulmonary Alveoli; Pulmonary Surfactant-Associated Proteins; Pulmonary Surfactants
PubMed: 2195058
DOI: 10.1172/JCI114670 -
Journal of Oleo Science 2016Pulmonary surfactant (PS) preparations based mainly on bovine or porcine extracts are commonly administered to patients with neonatal respiratory distress syndrome... (Review)
Review
Pulmonary surfactant (PS) preparations based mainly on bovine or porcine extracts are commonly administered to patients with neonatal respiratory distress syndrome (NRDS) for therapy. The preparations are sufficiently effective to treat NRDS; however, they are associated with a risk of infection and involve costly purification procedures to achieve batch-to-batch reproducibility. Therefore, we investigated the mechanism and interfacial behavior of synthetic PS preparations containing a mimicking peptide (KLLKLLLKLWLKLLKLLL, Hel 13-5). In particular, a hybrid PS formulation with fluorinated amphiphiles is reported from the perspective of surface chemistry. Fluorinated amphiphiles are characterized by exceptional chemical and biological inertness, high oxygen-dissolving capacity, low surface tension, excellent spreading ability, and high fluidity. These properties are superior to those for the corresponding hydrocarbon analogs. Indeed, a small amount of fluorinated long-chain alcohols enhances the effectiveness of the model PS preparation for in vitro pulmonary functions. Moreover, the mode of the improved efficacy differs depending on the hydrophobic chain length in the alcohols. For alcohols with a short fluorocarbon (FC) chain, the monolayer phase of the model PS preparation remains disordered (fluidization). However, the addition of alcohols containing a long FC chain reduces the disordered/ordered phase transition pressure and the growth of ordered domains of the monolayer (condensation). Furthermore, repeated compression-expansion isotherms of the monolayers, which can simulate respiration in the lung, suggest irreversible elimination of the short-FC alcohol into the subphase and enhancement of the squeeze-out phenomenon of certain PS components by solid-like monolayer formation induced by the long-FC alcohol. We demonstrated that fluorinated amphiphiles may be used as additives for synthetic or commercial PS preparations for RDS treatment.
Topics: Chemical Phenomena; Fatty Alcohols; Fluorocarbons; Hydrophobic and Hydrophilic Interactions; Phase Transition; Pulmonary Surfactants; Respiratory Distress Syndrome, Newborn
PubMed: 26833282
DOI: 10.5650/jos.ess15222 -
European Journal of Medical Research Dec 2009Beside neonatal respiratory distress syndrome, secondary surfactant deficiency may occur in patients with mature lungs. Recent studies revealed quantitative and... (Review)
Review
Beside neonatal respiratory distress syndrome, secondary surfactant deficiency may occur in patients with mature lungs. Recent studies revealed quantitative and qualitative changes of lung surfactant in pulmonary thromboembolism (PTE) concerning the total phospholipids content in BAL fluid, alterations in surfactant phospholipids classes and a large-to-small aggregates ratio. Reduced expression of surfactant protein A (SP-A) mRNA and SP-A in lung tissue after pulmonary embolism was found. Serum levels of SP-A were significantly higher in patients with PTE than in other lung diseases, except COPD. Surfactant changes in PTE may result from damage of type II cells by hypoxia, leakage of plasma proteins into the airspaces and/or by reactive oxygen species. They can contribute to lung atelectasis and edema, and a further reduction in oxygen saturation as seen in clinical picture of PTE. Surfactant changes are reliable marker of lung injury that might become a prognostic indicator in patients with pulmonary thromboembolism.
Topics: Humans; Pulmonary Embolism; Pulmonary Surfactant-Associated Protein A; Pulmonary Surfactants
PubMed: 20156722
DOI: 10.1186/2047-783x-14-s4-38 -
Swiss Medical Weekly 2013Pulmonary surfactant is a complex mixture of unique proteins and lipids that covers the airway lumen. Surfactant prevents alveolar collapse and maintains airway patency... (Review)
Review
Pulmonary surfactant is a complex mixture of unique proteins and lipids that covers the airway lumen. Surfactant prevents alveolar collapse and maintains airway patency by reducing surface tension at the air-liquid interface. Furthermore, it provides a defence against antigen uptake by binding foreign particles and enhancing cellular immune responses. Allergic asthma is associated with chronic airway inflammation and presents with episodes of airway narrowing. The pulmonary inflammation and bronchoconstriction can be triggered by exposure to allergens or pathogens present in the inhaled air. Pulmonary surfactant has the potential to interact with various immune cells which orchestrate allergen- or pathogen-driven episodes of airway inflammation. The complex nature of surfactant allows multiple sites of interaction, but also makes it susceptible to external alterations, which potentially impair its function. This duality of modulating airway physiology and immunology during inflammatory conditions, while at the same time being prone to alterations accompanied by restricted function, has stimulated numerous studies in recent decades, which are reviewed in this article.
Topics: Allergens; Asthma; Humans; Pulmonary Surfactants
PubMed: 23896983
DOI: 10.4414/smw.2013.13818 -
Respiratory Research 2002Pulmonary surfactant is a unique mixture of lipids and surfactant-specific proteins that covers the entire alveolar surface of the lungs. Surfactant is not restricted to... (Review)
Review
Pulmonary surfactant is a unique mixture of lipids and surfactant-specific proteins that covers the entire alveolar surface of the lungs. Surfactant is not restricted to the alveolar compartment; it also reaches terminal conducting airways and is present in upper airway secretions. While the role of surfactant in the alveolar compartment has been intensively elucidated both in health and disease states, the possible role of surfactant in the airways requires further research. This review summarizes the current knowledge on surfactant functions regarding the airway compartment and highlights the impact of various surfactant components on allergic inflammation in asthma.
Topics: Animals; Asthma; Humans; Pulmonary Surfactant-Associated Proteins; Pulmonary Surfactants; Surface Tension
PubMed: 11806839
DOI: 10.1186/rr176