Effect Of Pulmonary Surfactant Research Articles

Effect of pulmonary surfactant on the dispersion of carbon nanoparticles

Carbon nanoparticles (CNs) are widely used and there has been a great concern about their potential adverse effects on human health. CNs can directly interact with the pulmonary surfactant (PS) lining of alveoli, but the dispersion state of CNs at PS film has not yet been explored. Accumulating evidences indicated that the degree of dispersion of nanoparticles has a strong influence on their biological activities. This study investigated the effect of PS and its major components on the dispersion state of three representative CNs (fullerene C60, nano carbon powder, graphene oxide). The results demonstrated that suspended concentrations of all three CNs were lower in the presence of PS and its lipid component dipalmitoylphosphatidylcholine (DPPC) than in the presence of bovine serum album (BSA). Compared with PS and DPPC, BSA notably reduced the hydrodynamic diameters of CNs. In addition, the absolute zeta potentials of CNs in the presence of BSA was higher than those in the presence of PS or DPPC, and this result corresponds to the increase of surface oxygen contents of CNs, indicating that relatively high surface oxygen content is beneficial for the dispersion of CNs in alveolus. π-A isotherms demonstrated that the surface tension and phase behavior of PS were obviously altered in the presence of CNs. This study revealed the role of PS and different active components in the dispersion of CNs, which is helpful for deeply understanding CNs alveolar transport and the associated potential hazards to lung health. • Interaction of PS with carbon nanoparticles (CNs) leads to the aggregation of CNs. • Lipids and protein components of PS exert different effects on CNs dispersion. • Hydrodynamic diameter/zeta potential impact the dispersion of CNs with PS component. • Surface oxygen content of CNs governs the dispersion of CNs. • CNs exposure leads to the alternation of phase behavior of PS film.

The effect of pulmonary surfactant on the airway smooth muscle after lipopolysaccharide exposure and its mechanisms.

Pulmonary surfactant has a relaxing effect on the airway smooth muscle (ASM), which suggests its role in the pathogenesis of respiratory diseases associated with hyperreactivity of the ASM, such as asthma and chronic obstructive pulmonary disease (COPD). The ASM tone may be directly or indirectly modified by bacterial wall component lipopolysaccharide (LPS). This study elucidated the effect of LPS on the ASM reactivity and the role of surfactant in this interaction. The experiments were performed using ASM of adult guinea pigs by in vitro method of tissue organ bath (ASM unexposed-healthy or exposed to LPS under in vitro conditions) and ASM of animals intraperitoneally injected with LPS at a dose 1 mg/kg of b.w. once a day during 4-day period. Variable response of LPS was controlled by cyclooxygenase inhibitor indomethacin and relaxing effect of exogenous surfactant was studied using leukotriene and histamine receptor antagonists. The exogenous surfactant has relaxing effect on the ASM, but does not reverse LPS-induced smooth muscle contraction. The results further indicate participation of prostanoids and potential involvement of leukotriene and histamine H1 receptors in the airway smooth muscle contraction during LPS exposure.

Efficacy of pulmonary surfactant combined with caffeine citrate on neonatal respiratory distress syndrome treated with synchronized nasal intermittent positive pressure ventilation

Objective To investigate the clinical effects of pulmonary surfactant(PS) combined with caffeine citrate on neonatal respiratory distress syndrome(NRDS) treated with synchronized nasal intermittent positive pressure ventilation(SNIPPV). Methods We collected and analyzed 99 neonates who were diagnosed with NRDS and required SNIPPV treatment from January 2016 to June 2019 in NICU of Shengjing Hospital of China Medical University.According to the different treatment, they were divided into PS+ citrate caffeine combination group and control group.The control group(53 neonates)was treated by PS alone.The combination group(46 neonates)was treated with PS combined with caffeine citrate.The indexes of ventilator time, the time of using oxygen, length of hospital stay and complications were compared between the two groups. Results The indexes of ventilator time, the time of using oxygen and length of hospital stay of combination group were significantly shorter than those of the control group.The differences were statistically significant(P 0.05). Conclusion PS combined with caffeine citrate in the treatment of NRDS with SNIPPV could effectively improve the pulmonary function of infants.It could improve the neonatal survival rate and reduce complications.It is worth to be recommended. Key words: Neonatal respiratory distress syndrome; Synchronized nasal intermittent positive pressure ventilation; Pulmonary surfactant; Caffeine citrate

The effect of pulmonary surfactant on the in vitro activity of Iclaprim against common respiratory bacterial pathogens

The in vitro antimicrobial activity of iclaprim, a novel diaminopyrimidine, against common respiratory bacteria remained unchanged in the presence of pulmonary surfactant (Survanta®) at concentrations that greatly antagonized the antimicrobial activity of daptomycin. These results indicate that iclaprim could be a potential treatment for pneumonia caused by susceptible and multidrug resistant bacteria.

Effect of pulmonary surfactant on the dissolution, stability and uptake of zinc oxide nanowires by human respiratory epithelial cells

Inhaled nanoparticles (NPs) have high-deposition rates in the alveolar region of the lung but the effects of pulmonary surfactant (PS) on nanoparticle bioreactivity are unclear. Here, the impact of PS on the stability and dissolution of ZnO nanowires (ZnONWs) was investigated, and linked with their bioreactivity in vitro with human alveolar epithelial type 1-like cells (TT1). Pre-incubation of ZnONWs with Curosurf® (a natural porcine PS) decreased their dissolution at acidic pH, through the formation of a phospholipid corona. Confocal live cell microscopy confirmed that Curosurf® lowered intracellular dissolution, thus delaying the onset of cell death compared to bare ZnONWs. Despite reducing dissolution, Curosurf® significantly increased the uptake of ZnONWs within TT1 cells, ultimately increasing their toxicity after 24 h. Although serum improved ZnONW dispersion in suspension similar to Curosurf®, it had no effect on ZnONW internalization and toxicity, indicating a unique role of PS in promoting particle uptake. In the absence of PS, ZnONW length had no effect on dissolution kinetics or degree of cellular toxicity, indicating a less important role of length in determining ZnONW bioreactivity. This work provides unique findings on the effects of PS on the stability and toxicity of ZnONWs, which could be important in the study of pulmonary toxicity and epithelial-endothelial translocation of nanoparticles in general.

The clinical effect of pulmonary surfactant in treatment of preterm children respiratory distress syndrome

Objective To discuss the clinical effect of pulmonary surfactant in the treatment of preterm children respiratory distress syndrome (RDS).Methods 86 RDS premature children were randomly divided into two groups by digital number table methods,43 cases were in each group,the control group was given nasal continuous positive airway pressure (NCPAP) treatment,while the observation group was given intratracheal instillation PS on the basis of the control group.The arterial blood gases,outcome indicators of changes in circumstances were compared between the two groups.Results After treatment,the PaO2 and PaO2/FiO2 of the observation group were (67.10 ±3.88) mmHg and (191.30 ± 10.72) higher than (43.81 ± 3.78) mmHg and (81.71 ± 5.34) of pre-treatment and (53.35 ± 3.86) mmHg and (126.88 ± 8.50) of the control group (t =9.35,9.50,7.34,7.20,all P ＜ 0.05) ; while PaCO2 was (37.38 ± 3.65) mmHg significantly lower than (59.15 ± 4.27) mmHg of pre-treatment and (58.76 ±3.86) mmHg of the control group,the differences were statistically significance (t =10.15,7.62,all P ＜0.05);after treatment,the IVH and ROP incidence of the observation group were 4.65％ and 6.98％,which were significantly lower than 13.95％ and 16.28％ of the control group (x2 =7.68,7.39,all P ＜ 0.05) ; while the two groups showed no significant difference in incidence of BPD (P ＞ 0.05).Conclusion Pulmonary surfactant in the treatment of respiratory distress syndrome in premature children has significant effect,and it can improve lung function in children with disease outcome and prognosis. Key words: pulmonary surfactant; respiratory distress syndrome ; disease outcome

Clinical analysis of pulmonary surfactant in treatment of 30 cases with neonatal respiratory distress syndrome

Objective To explore the effect of pulmonary surfactant(PS) in the treatment of neonatal respiratory distress syndrome(NRDS).Methods According to whether using the PS,60 NRDS patients were divided into treatment group and control group.The blood-gas analysis index,oxygen time,mechanical ventilation time,hospitalization time and other indicators were analyzed.Results After 6h treatment,blood pH value (7.41 ± 0.11),PaO2 (69.8 ± 11.9) mm Hg and PaCO2 (48.7 ± 11.1)mm Hg in the treatment group were higher than those of the control group (7.24 ±0.13),(53.3 ±9.8)mm Hg,(59.1 ± 12.7)mm Hg(t =3.35,2.88,3.24,all P ＜0.05).In the treatment group,oxygen time (98.2 ± 29.2) h,the time of mechanical ventilation (77.6 ± 30.4) h and hospitalization time (12.9 ± 1.7)d,were also shorter than those of the control group (143.9 ± 26.5) h,(121.4 ± 22.9) h,(17.6 ±2.1) d (t =4.56,5.32,4.86,all P ＜ 0.05).Conclusion The application of PS in the treatment of NRDS can improve the lung function and lung aeration and reduce the time of mechanical ventilation. Key words: Pulmonary surfactants ; Respiratory distress syndrome; Infant, neonate

Effects of pulmonary surfactant in treatment of acute lung injury after cardiac surgery in infants

Acute lung injury is a severe complication after cardiac surgery performed with cardiopulmonary bypass in infant patients. Pulmonary surfactant has been successfully used in treating neonatal respiratory distress syndrome for many years. This study focused on exploring the clinical efficacy of exogenous pulmonary surfactant in treating infant patients with acute lung injury after cardiac surgery with the use of extracorporeal circulation. Twenty-three infants with ventricular septal defect (VSD) were enrolled in the study. None of the patients needed oxygen treatment nor ventilation before heart surgery. VSD repair operation was done under cardiopulmonary bypass, and acute lung injury was found postoperatively. Ten infant patients in the treatment group were given pulmonary surfactant by tracheal instillation during mechanical ventilating postoperatively. Thirteen patients in control group were randomly selected in the same period in hospital, and acute lung injury was diagnosed without pulmonary surfactant treatment after cardiopulmonary bypass. Blood samples were obtained from all the patients, and blood gas analysis was performed every 6 hours. Demographics (body weigh, age, gender, VSD diameter) and clinical characteristics (CPB time, oxygenation index, mean airway pressure, pH and PCO2) of all the patients were collected, and statistical analysis was done to compare the data between treatment and control group. In the first 24 hours after heart surgery, compared with the control group, a more increased oxygenation index (from 89.36 ± 12.69 to 285 ± 16.51) was observed in treatment group, and it was from 93.71 ± 11.82 to 133 ± 19.62 in the control group. There was a significant difference in oxygenation index between the two groups (P < 0.05). At the same time, the MAP (from 17.5 ± 3.18 to 10.4 ± 3.37) of the patients in comparison with the control group (from 18.2 ± 2.63 to 13.8 ± 2.55), a more significantly decreased MAP was observed in the treatment group (P < 0.05). There was no significant difference in pH and PCO2 between the two groups. The ventilation time in cardiac care unit was shorter in treatment group (17.43 ± 9.12) h compared with the control group [(30.97 ± 14.85) h, P < 0.05]. ICU stay time of treatment group (3.90 ± 1.34) d was shorter than that of control group [(6.18 ± 1.90) d, P < 0.05].Two infants of the control group died, but none in treatment group died. In this study, a satisfactory curative effect was observed for the treatment of acute lung injury with PS intratracheal instillation after heart surgery under cardiopulmonary bypass in infant patients. It can reduce the duration of mechanical ventilation and cardiac care unit stay and improve prognosis. In addition, this study was a pilot study and the limited sample size was probably the cause of insufficient statistical power. Further study of larger scale is needed.

In Vitro Effects of Pulmonary Surfactant on Macrophage Morphology and Function

The effects of pulmonary surfactant on the morphology and functioning of young macrophages were studied on the model of monocyte/macrophage differentiation in vitro and on macrophages of the bronchial alveolar lavage fluid. Surfactant is not a differentiation inductor, but it stimulated the maturation and phagocytic activity of young macrophages. The stimulatory effect of surfactant on phagocytic activity of macrophages persisted even after its removal from the culture medium.

Effect of Pulmonary Surfactant and Phospholipid Hexadecanol Tyloxapol on Recombinant Human-Insulin Absorption from Intratracheally Administered Dry Powders in Diabetic Rats

The purpose of the present study was to evaluate the enhancement effect of the natural pulmonary surfactant (PS) or its artificial substitute, phospholipid hexadecanol tyloxapol (PHT) on the bioavailability and hypoglycemic activity of recombinant human insulin (rh-insulin) in a pulmonary delivery system. PS- or PHT-loaded insulin formulation was administered to streptozotocin induced diabetic rats, at doses of 5 U/kg, 10 U/kg and 20 U/kg insulin, respectively. The hypoglycemic effect caused by PS or PHT containing rh-insulin was analyzed and the area above the curves (AAC) of serum glucose levels versus time, the minimum glucose concentration (C(min)), the time to C(min) (T(min)) and the pharmacological availability (PA%) were derived from the serum glucose profiles. Results showed that PS and PHT caused significantly decrease in serum glucose levels. The decrease in plasma glucose levels continued for about 5 h after the nadir. The highest AAC value was obtained when 20 U/kg rh-insulin with PS or PHT as absorption enhancer was administered to rats. AAC(0-360 min) of PS- or PHT-loaded rh-insulin was 2-3 times as much as that without PS or PHT and PA% increased by 1.3-2 fold. Thus, the extent of oral absorption of insulin from PS- or PHT-loaded particles was significantly greater when compared with that without them. In addition, PHT as well as PS did not change the lactate dehydrogenase (LDH) activity, alkaline phosphatase (AKP) activity and N-acetyl-β-D-glucoaminidase (NAG) activity in bronch fluid which are sensitive indicators of acute toxicity to lung cells in bronchoalveolar lavage (BAL). It is concluded that PS and PHT is a promising absorption enhancer for pulmonary delivery systems of large molecule drugs as rh-insulin.

Effect of pulmonary surfactant on the incidence of bronchopulmonary dysplasia

Objective To explore, the effect of different dosage of pulmonary surfactant (PS) on the inci-dence of bronchopulmanary dysplasia. Method Four hundred and three premature infants with hyaline membrane disease were divided into 3 groups according to the dose of PS: low-dose group (L-PS group, ≤ 100 mg/kg, n =188) ,high-dose group(H-PS group, > 100 mg/kg, n = 94) and no-PS group (N-PS group, n = 121). The frac-tional inspired oxygen(FiO2) and ptlmonary oxygenating function before and after 6 hours treatment were observed and the durations of oxygen therapy and mechanical ventilation, frequency of repeated intubafion, length of hospi-talization and the incidence of BPD were compared among the three groups. Results After 6 hours PS administra-tion, the FiO2,oxygen index and duration of oxygen therapy and mechanical ventilation were significantly decreased (P <0.05), while PO2 and the arterio-alveolar partial pressure of oxygen were significantly increased (P <0.05)in the H-PS and L-PS groups, compared with the N-PS group. Compared with the L-PS and N-PS groups,the H-PS group showed a decreased incidence of BPD. Conclusions PS administration could improve the pul-monary oxygenation and prevent the development of BPD, especially in high-dose. Key words: Surfactant; Hyaline membrane disease; Bronchopulmonary dysplasia; Infant, Premature

Effects of curosurf on neonatal respiratory distress syndrome by different administration means

Objective To evaluate the curative and prophylactic effects of pulmonary surfactant (PS) on neonatal respiratory distress syndrome (NRDS) by two different administration means. Methods 35 neonates with NRDS were divided into groups Ⅰ and Ⅱ randomly, prophylactic group were randomly divided into groups Ⅲ and Ⅳ, the means of administration in all patients was through tracheal tube. Neonates in group Ⅰ and Ⅲ, were given curosurf in several times with different posture, group Ⅱ and IV were given in one time with supine position. Blood gas analysis, index of mechanical ventilation, the duration of mechanical ventilation, hours of oxygen requirement and hospitalization between Ⅰ and Ⅱ group, the incidence of NRDS between Ⅲ, and IV group were analyzed and compared before and after treatment. Results After treatment for 6 and 24 hours, the oxygenation and lung function of group Ⅰ and Ⅱ improved respectively (P<0.05), the total times of assisted ventilation, Supplemental oxygen therapy and hospitalization were significantly decreased, the differences of those index were no significant between Ⅰ and Ⅱ group (P0.05), the incidence of NRDS have no different between Ⅲ and IV group. Conclusion Pulmonary surfactant is effective and safe for treating and prophylacting NRDS, and have no relationship with the means of administration. Key words: Respiratory distress syndrome; Pulmonary surfactant-associated protein-A; Infants; newborn

Intrapulmonary Distribution of Intravenous Telavancin in Healthy Subjects and Effect of Pulmonary Surfactant on In Vitro Activities of Telavancin and Other Antibiotics

Steady-state concentrations of telavancin, a novel, bactericidal lipoglycopeptide, were determined in the plasma, pulmonary epithelial lining fluid (ELF), and alveolar macrophages (AMs) of 20 healthy subjects. Telavancin at 10 mg of drug/kg of body weight/day was administered as a 1-h intravenous infusion on three successive days, with bronchoalveolar lavage performed on five subjects, each at 4, 8, 12, and 24 h after the last dose. Plasma samples were collected before the first and third infusions and at 1, 2, 3, 4, 8, 12, and 24 h after the third infusion. The plasma telavancin concentration-time profile was as reported previously. Telavancin (mean +/- standard deviation) penetrated well into ELF (3.73 +/- 1.28 microg/ml at 8 h and 0.89 +/- 1.03 microg/ml at 24 h) and extensively into AMs (19.0 +/- 16.8 microg/ml at 8 h, 45.0 +/- 22.4 microg/ml at 12 h, and 42.0 +/- 31.4 microg/ml at 24 h). Mean concentrations in AMs and plasma at 12 h were 45.0 microg/ml and 22.9 microg/ml (mean AM/plasma ratio, 1.93), respectively, and at 24 h were 42.0 microg/ml and 7.28 microg/ml (mean AM/plasma ratio, 6.67), respectively. Over the entire dosing interval, telavancin was present in ELF and AMs at concentrations up to 8-fold and 85-fold, respectively, above its MIC 90 for methicillin-resistant Staphylococcus aureus (0.5 microg/ml). Pulmonary surfactant did not affect telavancin's in vitro antibacterial activity. Telavancin was well tolerated. These results support the proposal for further clinical evaluation of telavancin for treating gram-positive respiratory infections.

Effects of lung surfactants on rifampicin release rate from monodisperse rifampicin-loaded PLGA microspheres

We have prepared inhalable and monodisperse poly(lactide- co-glycolide) (PLGA) microspheres targeting tubercle bacilli residing in alveolar macrophages. The effects of pulmonary surfactant on the rifampicin (RFP) release rate from RFP-loaded poly (lactide- co-glycolide) microspheres were studied. Also, those of their surface properties of RFP-loaded PLGA microspheres were studied. The RFP release from RFP/PLGA microspheres was accelerated by adsorption of pulmonary surfactant on the particle surface. The fastest RFP release rate was observed from pulmonary surfactant-adsorbed PLGA particles in pH 7.4 buffer solution compared with those in pH 4.0 buffer solution and saline solution. The slowest release rate was observed in the case when saline solution was used as dispersion phase of RFP/PLGA microspheres, although RFP release rate increased by the addition of pulmonary surfactant. From these results it is suggested that when RFP/PLGA microspheres are administrated by inhalation, the RFP release rates from the particles which are not taken up by alveolar macrophages and remain in the alveoli will be small. On the other hand, the RFP release rates and release amounts will be high after RFP/PLGA microspheres are taken up by alveolar macrophages existing in phagosomes, but they become relatively small after RFP/PLGA microspheres move into phagosome–lysosomes by the fusion of phagosomes with lysosomes. The absolute values of the electrophoretic mobility of PLGA microspheres increased by the adsorption of pulmonary surfactants on the surfaces of PLGA microspheres. By analyzing the experimental data using the soft-particle theory, it was indicated that the microspheres became ‘softer’ and the surface charge density of microspheres increases by the degradation. On the other hand, the surface of PLGA microspheres became harder and the electric charge density increased by the adsorption of pulmonary surfactant on the surfaces of PLGA microspheres. The changes in the surface charge density with degradation became larger by the adsorption of the lung surfactant on PLGA microsphere surfaces. It is considered that the changes in surface properties of PLGA microspheres affect their uptake efficiency by alveolar macrophage.

Effect of pulmonary surfactant on TNF-α-activated endothelial cells and neutrophil adhesion in vitro

Pulmonary surfactant given to infants and adults with respiratory failure is metabolized and recycled to a large extent. A small proportion also enters the circulation in cases of increased permeability of the alveolar-capillary membrane. We therefore investigated whether exogenous surfactants such as a natural bovine (natSF) or a synthetic (synSF) preparation had an impact on inflammatory conditions involving the adhesion of neutrophils to endothelial cells. Human umbilical cord vein endothelial cells (HUVEC) were plated on coverslips until confluence, activated by tumor necrosis factor-alpha and incubated with or without surfactant in the media. Human neutrophils passed the HUVEC layer in a flow chamber and interactions were visualized using a video microscope. To test if surfactant affected the expression of cell adhesion molecules, RT-PCR analyses were performed for E-selectin, vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1). Using concentrations between 50 and 300μg/ml of surfactant in the pre-incubation media the number of adherent neutrophils increased by 10–20% at the higher concentration of the natSF (*P<0.05) whereas the synSF had no effect. Increased neutrophil adhesion was associated with a significant up-regulation of mRNA levels for E-selectin and VCAM-1; mRNA levels for ICAM-1, however, were not affected by the presence of surfactant. These observations indicate that natSF but not synSF might have pro-inflammatory effects when higher amounts of the exogenous dose reach the circulation. This might be explained by different fatty acid profiles, e.g. the presence of arachidonic acid in the natSF or higher concentrations of surfactant-associated protein-C in the synSF.

Lysophosphatidylcholine Abrogates the CR1 Preserving Effect of Surfactant on Quartz-Exposed Human Granulocytes

The effects of pulmonary surfactant on granulocytes were studied by flow cytofluorometry. Cells from hemolyzed blood were first activated by N-formyl-methionyl-leucyl-phenylalanine (fMLP) which mobilizes complement receptor 1 (CR1) from the intracellular pool to the cell surface. The reduced CR1 expression observed after quartz incubation was abolished by a porcine surfactant preparation containing phospholipids and the hydrophobic surfactant proteins. Phospholipids alone had no preservative capacity. However, addition of the surfactant proteins to the phospholipids did not restore the CR1 values to that of intact surfactant, probably due to changed protein structure during the purification procedure. Heating of surfactant at 37°C up to 72 h reduced the preservative effect of surfactant on CR1 expression. Congruent results of CR1 expression were achieved when 1–10% lysophosphatidylcholine was added to the surfactant preparations. Our results imply that lysophosphatidylcholine formed during storage of surfactant at elevated temperatures influences CR1 expression on granuloyctes.

Effects of pulmonary surfactant on macrophage migration: suppression of chemokinesis by surfactant phospholipid and enhancement of chemotaxis by surfactant protein.

We fractionated the bronchoalveolar lavage fluid (BALF) from normal rabbit lungs into several fractions by high speed centrifugation and ethanol-ether extraction. Random migration, chemokinesis and chemotaxis of freshly harvested alveolar macrophages (AM), 24 h cultured AM, and peritoneal exudate cells (PEC) were assayed in vitro using a modified, under agarose method and a blind well chemotactic chamber method. Freshly harvested AM demonstrated little random migration compared with PEC. However, when freshly harvested AM were pre-incubated in surfactant free medium for 24 h, the cells showed the same rate of migration as PEC. The increased migration of the 24 h cultured AM was partially suppressed by the presence of all BALF fractions containing high proportions of phospholipid. The inhibition by Fr-L (a fraction enriched in phospholipids) was reversed by normal serum, but not by heat-inactivated serum, cholesterol, synthetic dipalmitoyl phosphatidyl choline, or indomethacin. Fr-L markedly suppressed macrophage chemokinesis but did not affect on macrophage chemotaxis. Alternatively, Fr-P, a delipidated preparation of surfactant consisting mainly of protein, had no effect on macrophage chemokinesis but increased the chemotaxis of PEC to zymosan-activated serum. We conclude that surfactant phospholipid suppresses AM migration, while surfactant protein increases macrophage chemotaxis.

Pulmonary surfactant inhibits cationic liposome-mediated gene delivery to respiratory epithelial cells in vitro.

Cationic lipid-mediated transfection of the alveolar epithelium in vivo will require exposure of plasmid DNA and cationic lipids to endogenous surfactant lipids and proteins in the alveolar space. Effects of pulmonary surfactant and of surfactant constituents on transfection in vitro of two respiratory epithelial cell lines (MLE-15 and H441) with a plasmid encoding the luciferase reporter gene were studied using two cationic lipid formulations: 1,2-dimyristyloxypropyl-3-dimethyl-hydroxyethyl ammonium bromide/cholesterol (DMRIE/C) and 1,2-dioleoyl-3-trimethylammonium propane/dioleoyl phosphatidylethanolamine (DOTAP/DOPE). Gene expression, as assessed by luciferase activity, decreased as increasing concentrations of natural surfactant were added to cationic lipid-DNA complexes. Incorporation of phospholipids DOPC/DOPG or surfactant proteins SP-B or SP-C in the cationic lipid formulation inhibited transfection. A fluorescent lipid mixing assay was used to determine the effects of surfactant proteins SP-B and SP-C on mixing between cationic lipid-DNA complexes and surfactant lipid vesicles. Mixing between DOPC/DOPG vesicles and cationic lipid-DNA complexes in the absence of added proteins amounted to 10-20%. Addition of SP-B or SP-C increased the mixing of DOPC/DOPG vesicles with DOTAP/DOPE-DNA complexes, but not DMRIEC-DNA complexes. These results demonstrate that pulmonary surfactant lipids and proteins inhibit transfection with cationic lipid-DNA complexes in vitro, and may therefore represent a barrier to gene transfer in the lung.

Inhibitory effect of pulmonary surfactant on Sendai virus infection in rat lungs

Intranasal infection of rats with active (infectious) Sendai virus enhances secretion of tryptase Clara, a Sendai virus-activating protease, into the bronchial lumen by Clara cells of the bronchial epitheliums, and inversely suppresses secretion of pulmonary surfactant, an inhibitor of the protease, into the lumen [Kido H et al. (1993) FEBS Lett 322: 115-119]. A trypsin-resistant mutant, TR-2, showed similar effects, although its replication was restricted to a single cycle in the lungs. In contrast, neither nonactive (noninfectious) wild-type virus possessing receptor-binding activity and lacking envelope fusion activity nor UV-inactivated virus retaining receptor binding and envelope fusion activities altered the mode of secretions. These results indicate that viral replication is required for producing a condition in the bronchial lumen for proteolytic activation of progeny virus, thereby infection is extended to a fatal pneumonia. On the other hand, intranasal administration of infected rats with pulmonary surfactant suppressed activation of progeny virus and pathological changes in the lungs, suggesting a therapeutic use of pulmonary surfactant for influenza pneumonia.

Pulmonary Surfactant Films Affected by Solvent Vapors

Pulmonary surfactant obtained from rabbit lung lavage was evaluated with the pulsating bubble surfactometer. Because surfactant forms a monomolecular film at the air-liquid interface consisting mainly of phospholipids, solvent vapors, which might be inhaled, could have a destructive influence on the surfactant monolayer. To assess the risk of such an inhalation, vapors from five solvents--halothane, chloroform, enflurane, acetone, and diethyl ether--were made to flow into the bubble of the surfactometer as it pulsated for 30 sec, i.e., during 10 pulsations. The vapors from halothane and chloroform, excellent solvents of dipalmitoyl-phosphatidylcholine (DPPC), had a destabilizing effect evidenced by the fact that surface tension at minimal bubble size increased from 0 to as high as 20 mN/m. When the vapors were replaced with a flow of room air, the pressure tracing promptly returned to normal. The concentration of halothane vapor, however, had to be at least 20%, a concentration much higher than that used for anesthesia, to have a destabilizing effect on pulmonary surfactant. Twenty-five percent enflurane vapor had a less pronounced yet conspicuous impact. With 25% acetone and diethyl ether vapors, poor solvents of DPPC, surface tension at minimal bubble size remained unaffected. We conclude that vapors of halothane and chloroform, if inhaled in high concentration, might instantaneously obliterate the stabilizing effect of pulmonary surfactant but that anesthetic concentrations of halothane have no effect.