Proteins SP-C Research Articles

Exogenous surfactant prevents hyperoxia-induced lung injury in adult mice

BackgroundIn addition to the risk of developing ventilator-induced lung injury, patients with ARDS are at risk of developing hyperoxic injury due the supra-physiological oxygen supplementation clinically required to reverse hypoxemia. Alterations of endogenous surfactant system participate in the pulmonary dysfunction observed in ARDS. Administration of exogenous surfactant could have protective effects during hyperoxia.MethodsMale BALB/c mice (8–10 weeks), a strain highly sensitive to hyperoxia, received the exogenous surfactant-containing protein SP-B and SP-C by intranasal instillation 12 h before starting 24 h of exposure to hyperoxia in an inhalation chamber and were compared to mice receiving hyperoxia alone and to controls subjected to normoxia.ResultsCompared to the hyperoxia group, the administration of exogenous surfactant was able to reduce lung inflammation through a reduction in the influx of neutrophils and inflammatory biomarkers such as TNF, IL-17, and HMGB1 expression. The antioxidant activity prevented oxidative damage by reducing lipid peroxidation and protein carbonylation and increasing superoxide dismutase activity when compared to the hyperoxia group.ConclusionOur results offer new perspectives on the effects and the mechanism of exogenous surfactant in protecting the airway and lungs, in oxygen-rich lung microenvironment, against oxidative damage and aggravation of acute inflammation induced by hyperoxia.

Expression of Lung Surfactant Proteins SP-B and SP-C and Their Regulatory Factors in Fetal Lung of GDM Rats.

This study investigated the expression of lung surfactant proteins (SP-B and SP-C), and regulatory factors [forkhead box A2 (FOXA2) and nitrolyogenic FOXA2 (N-FOXA2)] in the fetal lung of rats with gestational diabetes mellitus (GDM) in order to study the mechanism of pulmonary dysplasia. The rat GDM model was established by using streptozotocin intraperitoneally in the first stage of pregnancy. There were 10 rats in the GDM group, and 10 healthy rats in normal control group without any treatment. Fetal lungs of two groups were taken at day 21 of pregnancy. Blood glucose levels of maternal rats and fetal rats were measured by Roche blood glucose meter. The histological changes in the fetal lung were observed under the light microscope in both groups. The SP-B, SP-C and FOXA2 were determined in the fetal lung of two groups immunohistochemically. The expression levels of SP-B, SP-C, total FOXA2, FOXA2 in nucleus (n-FOXA2), N-FOXA2 proteins were detected by Western blotting, and the relative expression levels of SP-B, SP-C, FOXA2 mRNA in the fetal lung of two groups were detected by RTPCR. The results showed that blood glucose levels of maternal rats and fetal rats in GDM group were higher than those in control group. The light microscope revealed fetal lung development retardation in GDM group. The expression of SP-B and SP-C in GDM group was significantly reduced as compared with control group (P<0.05). As compared with control group, the n-FOXA2 expression was significantly decreased in the fetal lung tissue, and N-FOXA2 was significantly increased in control group (P<0.05), but there was no significant changes in the total FOXA2 (P>0.05). It was concluded that GDM can cause fetal lung development and maturation disorders, and FOXA2 in fetal lung tissue decreases while nitrocellulose FOXA2 increases.

Intonation of Nrf2 and Hif1-α pathway by curcumin prophylaxis: A potential strategy to augment survival signaling under hypoxia

BackgroundPulmonary surfactant oxidation leads to alveolar collapse- a condition often noticed in high altitude pulmonary edema (HAPE). The present study was aimed to determine the effect of curcumin prophylaxis in augmenting the phase II antioxidant enzymes and surfactant proteins expression in enabling the pulmonary surfactant homeostasis under hypoxia. MethodsA549 cells were exposed to 3% hypoxia for different time durations (1 h, 3 h, 6 h, 12 h and 24 h). The Cells were pretreated (1 h) with 10 μM curcumin and exposed to hypoxia. The in-vivo results were extrapolated into in–vivo system using male Sprague Dawley rats, exposed to a stimulated altitude of 7620 m for 6 h. The rats were supplemented with curcumin (50 mg/kgBW) 1 h prior to hypoxia exposure. ResultsResults showed that, the expression of surfactant proteins (SPs) A and B decreased from 3 h of hypoxic exposure, whereas expression of SP-C and SP-D proteins were increased within 1 h of hypoxic exposure over control cells. Hypoxic exposure resulted into significant increase in protein and lipid peroxidation (p < 0.001), reduced levels of antioxidants (GSH, GPx and SOD) (p < 0.001) along with significant down regulation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and Heme oxygenase-1 (HO-1) in A549 cells over control. However, the curcumin supplementation both in-vitro and in-vivo resulted into increased expressions of HO-1 and Nrf2 significantly (p < 0.001), which enabled the cells in balanced expression of SPs with reduced levels of oxidants. Further curcumin significantly enhanced the levels of antioxidant enzymes in BALF along with stabilized expression of hypoxia inducible factor 1(HIF-1α) followed by reduced expression of vascular endothelial growth factor (VEGF) in lungs of rats. The immunohistochemistry observations provided substantial evidence of enhanced surfactant protein expressions in lungs of curcumin administered hypoxia exposed rats. ConclusionThese results indicate that curcumin augment survival signaling by reinforcing the induction of phase II antioxidant enzymes thereby enabling the pulmonary surfactant homeostasis under hypoxia.

Progress towards recombinant synthesis of pulmonary surfactant proteins SP-B and SP-C

Progress towards recombinant synthesis of pulmonary surfactant proteins SP-B and SP-C

Homo- and hetero-oligomerization of hydrophobic pulmonary surfactant proteins SP-B and SP-C in surfactant phospholipid membranes

Pulmonary surfactant is a lipid/protein mixture that reduces surface tension at the respiratory air-water interface in lungs. Among its nonlipidic components are pulmonary surfactant-associated proteins B and C (SP-B and SP-C, respectively). These highly hydrophobic proteins are required for normal pulmonary surfactant function, and whereas past literature works have suggested possible SP-B/SP-C interactions and a reciprocal modulation effect, no direct evidence has been yet identified. In this work, we report an extensive fluorescence spectroscopy study of both intramolecular and intermolecular SP-B and SP-C interactions, using a combination of quenching and FRET steady-state and time-resolved methodologies. These proteins are compartmentalized in full surfactant membranes but not in pure 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) vesicles, in accordance with their previously described preference for liquid disordered phases. From the observed static self-quenching and homo-FRET of BODIPY-FL labeled SP-B, we conclude that this protein forms homoaggregates at low concentration (lipid:protein ratio, 1:1000). Increases in polarization of BODIPY-FL SP-B and steady-state intensity of WT SP-B were observed upon incorporation of under-stoichiometric amounts of WT SP-C. Conversely, Marina Blue-labeled SP-C is quenched by over-stoichiometric amounts of WT SP-B, whereas under-stoichiometric concentrations of the latter actually increase SP-C emission. Time-resolved hetero-FRET from Marina Blue SP-C to BODIPY-FL SP-B confirm distinct protein aggregation behaviors with varying SP-B concentration. Based on these multiple observations, we propose a model for SP-B/SP-C interactions, where SP-C might induce conformational changes on SP-B complexes, affecting its aggregation state. The conclusions inferred from the present work shed light on the synergic functionality of both proteins in the pulmonary surfactant system.

Characterising the surface activity of recombinant pulmonary surfactant proteins SP-B and SP-C together with synthetic analogues: Potential tear film supplements

Characterising the surface activity of recombinant pulmonary surfactant proteins SP-B and SP-C together with synthetic analogues: Potential tear film supplements

Immunolocalization of Surfactant Proteins SP-A, SP-B, SP-C, and SP-D in Infantile Labial Glands and Mucosa.

Surfactant proteins in different glandular structures of the oral cavity display antimicrobial activity for protection of invading microorganisms. Moreover, they are involved in lowering liquid tension in fluids and facilitate secretion flows. Numerous investigations for studying the occurrence of surfactant proteins in glandular tissues were performed using different methods. In the oral cavity, minor salivary glands secrete saliva continuously for the maintenance of a healthy oral environment. For the first time, we could show that infantile labial glands show expression of the surfactant proteins (SP) SP-A, SP-B, SP-C, and SP-D in acinar cells and the duct system in different intensities. The stratified squamous epithelium of the oral mucosa revealed positive staining for SPs in various cell layers.

Paradoxical Bactericidal Effects of Hydrophobic Lung Surfactant Proteins and Their Peptide Mimics Using Liposome Molecular Trojan.

Lung surfactant, besides alveolar stability, also provides defence against pathogens by surfactant proteins (SP), SP-A and SP-D. The hydrophobic proteins SP-B and SP-C enhance surface activity. An unusual and paradoxical effect of bovine LS and synthetic model LS with SP-B/-C was bactericidal to Staphylococcus aureus and Escherichia coli. Bacterial proliferation were investigated with bovine lung surfactant extract (BLES), dipalmitoylphosphatdylcholine, palmitooleylglycerol, in combination with SP-B/-C using standard microbiological colony forming unit (CFU) counts and structural imaging. BLES and other surfactant-SP-B/-C mixtures inhibit bacterial growth in the concentration range of 0 -7.5 mg/mL, at > 10 mg/mL paradoxical growth of both the bacterial species suggest antibiotic resistance. The lipid only LS have no effect on bacterial proliferation. Smaller peptide mimics of SP-B or SP-B1-25, were less efficient than SP-Cff. Ultra structural studies of the bacterial CFU using electron and atomic force microscopy suggest some membrane damage of S. aereus at inhibitory concentration of BLES, and some structural alteration of E. coli at dividing zones, suggesting utilization and incorporation of surfactant lipid species by both bacteria. The results depicted from in vitro studies are also in agreement with protein-protein interactions obtained from PatchDock, FireDock and ClasPro algorithm. The MD-simulation decipher a small range fluctuation of gyration radius of the LS proteins and their peptide mimics. The studies have alarming implications in the use of high dosages (100 mg/mL/kg body weight) of exogenous surfactant for treatment of respiratory distress syndrome, genetic knock-out abnormalities associated with these proteins, and the novel roles played by SP-B/C as bactericidal agents.

Quantification of surfactant proteins in tears of patients suffering from dry eye disease compared to healthy subjects

PurposeTo quantify and compare the amounts of surfactant proteins SP-A, SP-B, SP-C and SP-D in the tear fluid collected from patients with dry eye syndrome and from individuals with a healthy ocular surface. MethodsSchirmer strips were used to collect tear fluid from both eyes of 241 volunteers (99 men, 142 women; age range: 18–87 years). Dry eye syndrome was diagnosed by ophthalmologists in 125 patients, whereas the healthy control group comprised 116 individuals. The total protein concentration was determined via Bradford assay. The relative concentration of surfactant proteins SP-A through -D was measured by enzyme-linked immuno-sorbent assay (ELISA). ResultsThe mean relative concentrations of SP-A, SP-C and SP-D were significantly higher in the dry eye group as compared to the healthy controls (p<0.05, one-way ANOVA). SP-B was also detected at a higher concentration in the dry eye group, but the difference to the control group was not statistically significant. ConclusionsThe upregulation of SP-A and SP-D in the dry eye group is probably related to these proteins’ known antimicrobial and immunomodulatory effects at the ocular surface. It may represent a pathophysiological response to the inflammatory condition of the ocular surface in dry eye. The upregulation of SP-B and SP-C may represent an effort of the lacrimal system to reduce surface tension and thus to counteract the increased tendency of the tear film to tear in dry eye.

El surfactante pulmonar disminuye la invasión de neumocitos por el patógeno respiratorio "Haemophylus influenzae" no tipificante

Lung surfactant is a lipoprotein complex that lines the alveolar fluid and is the first barrier against respiratory pathogens. The pathogen non typeable Haemophilus influenzae (NTHi) causes persistent infections in patients of chronic obstructive pulmonary disease (COPD) due to its ability to be internalized and survive in pneumocytes. Our objective was to characterize the effect of the lipid component of pulmonary surfactant, with or without surfactant proteins SP-B and SP-C, in the invasion and adhesion of NTHi to pneumocytes. We found that multilamellar vesicles of surfactant, inhibited invasion of pneumocytes by NTHi, due at least in part to lower adhesion to epithelial cells. Moreover, unilamellar vesicles surfactant, that are endocytosed by pneumocytes, inhibited internalization of NTHi, but only the presence of SP-B and SP-C reduced adhesion of NTHi to epithelial cells. Our results show that surfactant lipids and SP-B and SP-C inhibit NTHi invasion of pneumocytes through various mechanisms.

Permeability of Pulmonary Surfactant Membranes is Modulated by Proteins SP-B and SP-C

Permeability of Pulmonary Surfactant Membranes is Modulated by Proteins SP-B and SP-C

Delivery of Lung Surfactant SP-C Based Nanostructures to Respiratory Air-Liquid Interfacial Films

The breathing function is sustained by Lung Surfactant (LS), a macromolecular complex lining the alveolar air-liquid interface. In the context of the physiology of the LS system, the absence or dysfunction of surfactant protein SP-C is associated with several lung diseases. With the main goal of developing new therapeutic tools for the treatment of patients with respiratory dysfunction, we have evaluated different methodologies from the field of nanotechnology using scaffolding molecules that break membranes in nanoscale particles incorporating membrane proteins in their natural environment. We have explored the scaffolding reversible encapsulation of lipid bilayers incorporating either palmitoylated or a non-palmitoylated recombinant version of SP-C for the study of its structure-function relationships. In this work, SP-C has been solubilized using nanoparticles made with different lipid composition (POPC, POPC/POPG, POPC/POPG/DPPC or the Native Surfactant Lipid Fraction), assessing them as a potential native-like environment in order to preserve the tridimensional structure and functional properties of the protein. The nanoparticles behave themselves as a highly adsorptive material in the air-liquid interface, where they inhibited pulmonary surfactant adsorption. When SP-C is incorporated into the nanoparticles the interfacial adsorption capability of the complex increased slightly depending on the palmitoylation state of the protein. We have also analyzed the interaction of the complexes with surfactant monolayers and bilayers. Fluorescently labeled nanocomplexes seem to associate to both lipid structures with no apparent lipid transfer. These nanostructures could then constitute an efficient vehicle to direct molecules such as proteins or drugs to the respiratory air-liquid interface.

Thin liquid films from a new synthetic pulmonary surfactant preparation

A new pulmonary surfactant with synthetic analogs of surfactant proteins SP-B and SP-C (CHF5633) was studied by the method of thin liquid films (foam and wetting films). For foam films dependences such as probability W for formation of black foam films vs. surfactant concentration (Cs), disjoining (capillary) pressure isotherms (Π(h)) and film thickness (h) were studied. The minimum CHF5633 concentration for a black foam film formation was established in 75μg/cm3 (after 30min). The results obtained were compared with those of therapeutic pulmonary surfactant preparations and in particular to Curosurf®, the one that showed the best profile among the tested animal-derived surfactants with respect to black film formation, stability and homogeneity. It was shown that with respect to stability surfactant CHF 5633 (from W/C curves) was very close to Curosurf®. The differences involved black foam film thicknesses which for the synthetic surfactant (at 200μg/cm3) were h=14.7nm and for Curosurf® (at 200μg/cm3), h=12.6nm, i.e. film thickness of the synthetic surfactant was larger, probably due to the larger quantities of surfactant protein analogs SP-B and SP-C contained in it and/or to the different phospholipid composition. The same was observed for h(Cs) dependence. For wetting films equilibrium thickness vs. degree of hydrophobicity on a solid surface was measured as well as wetting contact angles. Practically no significant difference in the wetting behaviour of the aqueous suspensions of natural surfactant preparation Curosurf® and CHF 5633 was established, however about 25% less Curosurf® was needed to achieve almost the same wetting behavior.

Recombinant expression of surfactant protein H (SFTA3) in Escherichia coli

Surfactant proteins are broadly understood to be an important structural and functional part of the lung surfactant system. These proteins influence the intra-alveolar surface tension and contribute to innate immunity of the lung. Beside the four already known surfactant proteins SP-A, SP-B, SP-C and SP-D, two novel SPs (SP-G/SFTA2 and SP-H/SFTA3) have recently been described. These show no sequential or structural similarity with the already known SPs. However, bioinformatic prediction tools suggest physicochemical properties, which have already been described for other surfactant proteins. Although it is known that SFTA2 and SFTA3 are expressed in different human tissues, their distinct functional properties remain unclear. Here, we describe the establishment of a stable expression system for recombinant SFTA3 protein synthesis in Escherichia coli. This gives rise to future experiments with the overall aim to further examine and characterize this novel protein in more detail.

A small key unlocks a heavy door: The essential function of the small hydrophobic proteins SP-B and SP-C to trigger adsorption of pulmonary surfactant lamellar bodies

The molecular basis involving adsorption of pulmonary surfactant at the respiratory air–liquid interface and the specific roles of the surfactant proteins SP-B and SP-C in this process have not been completely resolved. The reasons might be found in the largely unknown structural assembly in which surfactant lipids and proteins are released from alveolar type II cells, and the difficulties to sample, manipulate and visualize the adsorption of these micron-sized particles at an air–liquid interface under appropriate physiological conditions. Here, we introduce several approaches to overcome these problems. First, by immunofluorescence we could demonstrate the presence of SP-B and SP-C on the surface of exocytosed surfactant particles. Second, by sampling the released particles and probing their adsorptive capacity we could demonstrate a remarkably high rate of interfacial adsorption, whose rate and extent was dramatically affected by treatment with antibodies against SP-B and SP-C. The effect of both antibodies was additive and specific. Third, direct microscopy of an inverted air–liquid interface revealed that the blocking effect is due to a stabilization of the released particles when contacting the air–liquid interface, precluding their transformation and the formation of surface films. We conclude that SP-B and SP-C are acting as essential, preformed molecular keys in the initial stages of surfactant unpacking and surface film formation. We further propose that surfactant activation might be transduced by a conformational change of the surfactant proteins upon contact with surface forces acting on the air–liquid interface.

Hydrophobic Surfactant Proteins Strongly Induce Negative Curvature

The hydrophobic surfactant proteins SP-B and SP-C greatly accelerate the adsorption of vesicles containing the surfactant lipids to form a film that lowers the surface tension of the air/water interface in the lungs. Pulmonary surfactant enters the interface by a process analogous to the fusion of two vesicles. As with fusion, several factors affect adsorption according to how they alter the curvature of lipid leaflets, suggesting that adsorption proceeds via a rate-limiting structure with negative curvature, in which the hydrophilic face of the phospholipid leaflets is concave. In the studies reported here, we tested whether the surfactant proteins might promote adsorption by inducing lipids to adopt a more negative curvature, closer to the configuration of the hypothetical intermediate. Our experiments used x-ray diffraction to determine how the proteins in their physiological ratio affect the radius of cylindrical monolayers in the negatively curved, inverse hexagonal phase. With binary mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC), the proteins produced a dose-related effect on curvature that depended on the phospholipid composition. With DOPE alone, the proteins produced no change. With an increasing mol fraction of DOPC, the response to the proteins increased, reaching a maximum 50% reduction in cylindrical radius at 5% (w/w) protein. This change represented a doubling of curvature at the outer cylindrical surface. The change in spontaneous curvature, defined at approximately the level of the glycerol group, would be greater. Analysis of the results in terms of a Langmuir model for binding to a surface suggests that the effect of the lipids is consistent with a change in the maximum binding capacity. Our findings show that surfactant proteins can promote negative curvature, and support the possibility that they facilitate adsorption by that mechanism.

Effect of all-trans retinoic acid on proliferation of fetal alveolar epithelial type II cells and expression of pulmonary surfactant C and aquaporin 5

Objective To investigate the effect of all-trans retinoic acid (at-RA) on fetal alveolar epithe-lial type Ⅱ cells (fAECⅡs) proliferation and the expression of pulmonary surfactant C (SPC) as well as aquaporin 5 (AQP5). Methods fAECⅡs were isolated and purified from fetal lung of pregnant SD rats (19 days). After being cultured for 1 day, and the fAECⅡs were interfered by at-RA for 1, 2 and 3 days.Cell proliferation, viability as well as growth state, expressions of SPC mRNA as well as AQP5 mRNA and expressions of protein SPC as well as AQP5 were respectively detected by using 4, 5-dimethylthiazol-2-yl-2, 5-diphenyltetrazolium bromide (MTT), inverted microscope, real-time fluorescence quantitative PCR (RT-PCR ) and Western blot. Results (1)When fAECⅡs were treated with at-RA for 1 day, and the cell proliferation and viability did not change (P>0.05), while the proliferation and viability were significantly improved in 2 days (P<0.05), and the difference was the most obvious (P<0.05) at 3 days.(2)Compared with the control group, the cell growth state was better, and the cell adherence was tighter and the refraction was higher in at-RA group.(3)Compared with the control group, at-RA up-regulated the expressions of AQP5 mRNA and AQP5 protein(t=-19.58, -10.44, -16.01, -46.25, -12.79, -27.96, all P<0.05), and the percentages of control group were 281.07%, 766.67%, 1 163.33% and 792.65%, 1 310.52%, 1 561.56% in 1, 2 and 3 days respectively.(4)Compared with control group, the expressions of SP-C mRNA and SPC protein were up-regulated when cells were exposed to at-RA for 1 and 3 d, but while they were down-regulated at 2 days(protein: the percentages of control group were 615.480%, 369.450% and 11.269%, respectively; mRNA: 728.33%, 400.83%, 66.57%, respectively)(t=-26.34, -25.26, 13.80, -25.25, -31.71, 9.12, all P<0.05). Conclusions at-RA can promote the proliferation and differentiation of fAECⅡs, enhance the fAECⅡs viability, and improve the expression of SPC and AQP5. Key words: Retinoic acid; alveolar epithelial type Ⅱ cell; Pulmonary surfactant C; Aquaporin 5

Expression of lung surfactant proteins SP-B and SP-C and their modulating factors in fetal lung of FGR rats.

This study investigated the expression of lung surfactant proteins SP-B and SP-C, and their modulating factors TTF-1 and PLAGL2 in the fetal lung of rats with fetal growth restriction (FGR). The rat FGR model was established by prenatal hypoxia in the first stage of pregnancy, 180 rats for experiment served as hypoxia group, and 197 healthy rats served as normal control group. The FGR incidence in hypoxia was compared with that in normal control group. The histological changes in the fetal lung were observed under the light microscope and electronic microscope in two groups. The SP-B, SP-C, TTF-1 and PLAGL2 proteins were determined in the fetal lung of two groups immunohistochemically. The expression levels of SP-B, SP-C, TTF-1 and PLAGL2 protein and mRNA in the fetal lung of two groups were detected by using Western blotting and RT-PCR respectively. The FGR rat model was successfully established by using hypoxia. Pathologically the fetal lung developed slowly, and the expression levels of SP-B, SP-C, TTF-1 and PLAGL2 protein and mRNA in the fetal lung were significantly reduced in hypoxia group as compared with those in normal control group. It was suggested that maternal hypoxia in the first stage of pregnancy could induce FGR, and reduce the expression of SP-B and SP-C, resulting in the disorder of fetal lung development and maturation.

A Combined Effect of Proteins SP-B and SP-C and Membrane Curvature on Cholesterol Partition in Lung Surfactant Membranes: Answers from Fluorescence

Cholesterol is the major neutral lipid present in lung surfactant, a lipid-protein complex responsible for the stabilization of the air-liquid interface in mammalian lungs, which is essential for the breathing function. It has been proposed that cholesterol content is tightly regulated in surfactant and that protein SP-C could have a role in this respect. To further analyse the affinity of surfactant membranes for cholesterol in the absence or presence of proteins, we have used cyclodextrin as a cholesterol solubilising agent and a fluorescent analog of cholesterol, cholestatrienol (CTL), whose partition can be followed in membrane vesicles with different lipid/protein compositions and sizes. Our results suggest that there is a direct effect of vesicle size/curvature on the affinity of membranes for CTL. This is translated into lower partition coefficients (Kx) for membranes with higher curvatures, possibly caused by an increased exposure of CTL in more curved bilayers. Surfactant hydrophobic proteins SP-B and SP-C were found to have a curvature-independent effect on CTL mobility, as well as in the mobility of other probes such as transparinaric acid-sphingomyelin (tPA-SM) or diphenylhexatriene-phosphatidylcholine (DPH-PC) in membranes of the same composition. Furthermore, in the absence of SP-B, SP-C-containing liposomes were found to spontaneously split into 30 nm vesicles increasing membrane curvature regardless lipid composition, which correlated with a reduction of Kx compared to pure lipid systems. Taken all together, our results indicate that curvature alters cholesterol accessibility in surfactant lipid bilayers and that lung surfactant proteins disturb membranes in cholesterol containing domains, which may have important physiological consequences for cholesterol mobilization in lung surfactant membranes and films.

The distribution of human surfactant proteins within the oral cavity and their role during infectious diseases of the gingiva

The oral cavity with the teeth and the surrounding gingival epithelium, the periodontium, the salivary glands and other structures are open to the oral environment and thus exposed to multiple microbiological and pathogenic influences. To prevent permanent inflammatory processes such as gingivitis or periodontitis an efficient defense system is essential to ensure healthy and physiological function of the oral cavity and other interacting organic systems. Surfactant proteins (SPs), originally found in pulmonary tissue are important factors of the immune system and beyond this, support the stability and rheology of gas or fluid interfaces. This study aimed to analyze the distribution of surfactant proteins by means of Western blot and immunohistochemistry in salivary glands as well as in healthy and pathological saliva. The different expression patterns of SP-A, -B, -C and -D in healthy and pathological (periodontitis) saliva were determined using ELISA quantification. One further objective of the study was the first detection of two recent discovered proteins belonging to the surfactant protein family within human salivary glands and saliva. The results of the study reveal differences in protein expression of SP-A, -B, -C and -D within healthy and pathologic saliva. The concentration of the surfactant proteins SP-A, SP-C and SP-D is increased in saliva of people suffering from periodontal diseases, whereas by contrast, SP-B shows an opposite expression pattern. Furthermore, the results evidence the presence of SP-G and SP-H within saliva and salivary glands for the first time.