Pulmonary Surfactant-associated Protein A Research Articles

An extended-gate field-effect transistor (EG-FET) signal transducing combined with epitope molecular imprinting for selective chemosensing of chosen idiopathic pulmonary fibrosis (IPF) biomarkers

We propose a relatively rapid and straightforward procedure for the determination of chosen idiopathic pulmonary fibrosis (IPF) predictive protein biomarkers, vis., matrix metalloproteinase-1 (MMP-1) and surfactant-associated protein-A (SP-A), suitable for their determination in bodily fluids. IPF is a lethal lung disease, annually causing nearly as many deaths as breast cancer. Moreover, the coronavirus recently triggered acute exacerbation of patients suffering from IPF. Here, epitopes specific to the chosen IPF biomarkers were molecularly imprinted in a polymer as an alternative to imprinting fragile whole biomarkers’ molecules. A thin molecularly imprinted polymer (MIP) film-based recognition units were integrated by electropolymerization with gates of extended-gate field-effect transistors (EG-FETs) to fabricate biomarker-selective chemical sensors suitable as point-of-care testing (POCT) diagnostic devices. Either AQDDIDGIQAI or FKGNKYWAVQGQNV single-epitope imprinting allowed determining the MMP-1 biomarker in the 10 to 250 nM linear dynamic concentration range with a LOD of 7.5 or 2 nM, respectively. Simultaneous imprinting of three MMP-1 epitopes, vis., MIAHDFPGIGHK, HGYPKDIYSS, and FKGNKYWAVQGQNV, decreased this LOD to 0.1 nM, allowing for determining this biomarker in serum. Moreover, by FSSNGQSIT or YSDGTPVNYTNWYR single-epitope imprinting, chemosensors for SP-A were fabricated to show the versatility of epitope imprinting. These chemosensors selectively determined the SP-A biomarker with the LOD of 1.9 or 2.9 nM, allowing its determination in bodily fluids.

Effect research of two kinds of airway humidification solution for patients with tracheotomy of airway humidification

Objective To compare the influence of tracheotomy after two wet fluid on airway and provide the basis for clinical treatment and care. Methods A total of 30 patients with severe brain injury stay neurosurgery tracheotomy were divided into 0.45% sodium chloride group and ambroxol hydrochloride group with 15 cases each by random digits table method, two airway humidification liquid (0.45% sodium chloride, 0.9% sodium chloride + ambroxol hydrochloride)were each instilled in the trachea inner sleeve. Blood gas analysis was performed and the levels of serum lung surface active substances related protein-A (SP-A protein), interleukin-6, interleukin-8, tumor necrosis factor-alpha(TNF-α) were measured by enzyme linked immunosorbent assay (ELISA)before 1 d and after 3,7,14 d of tracheotomy. Results There were significant differences in arterial blood oxygen partial pressure, arterial carbon dioxide partial pressure, oxygenation index after 14 d of tracheotomy between ambroxol hydrochloride group and 0.45% sodium chloride group:(110.72±26.75) mmHg(1 mmHg=0.133 kPa) vs.(89.39±21.98) mmHg, (30.44±6.75) mmHg vs. (35.12±7.28) mmHg, 333.23±80.56 vs. 270.93±77.21,t=29.49,-8.63,7.44,P<0.01.There were significant differences in the levels of serum SP-A protein, interleukin -6, interleukin -8, TNF-α after 14 d of tracheotomy between ambroxol hydrochloride group and 0.45% sodium chloride group:(191.34±1.21) ng/L vs. (61.92±12.0) ng/L, (2.62±0.23) ng/L vs.(5.42±0.16) ng/L,(124.56±2.10) ng/L vs. (185.91±1.48) ng/L, (31.32±1.38) ng/L vs.(69.13±1.16) ng/L,t=75.72, -13.51, -23.89, -20.97,P<0.01. Conclusions The airway humidification effect of ambroxol hydrochloride group is better than 0.45% sodium chloride group, it can improve the wetting effect, and better protect the lung tissue, reduce the incidence of lung infection, make it an ideal airway humidification liquid. Key words: Craniocerebral trauma; Tracheotomy; Ambroxol; Pulmonary surfactant-associated protein A; Airway humidification

Role of cAMP-PKA signal transduction pathway in lidocaine-induced up-regulation of expression of surfactant protein-A in rat alveolar epithelial type II cells

Objective To evaluate the role of cyclic adenosine monophosphate-protein kinase A (cAMP-PKA) signal transduction pathway in lidocaine-induced up-regulation of the expression of surfactant protein-A (SP-A) in rat alveolar epithelial type Ⅱ cells (AEC Ⅱ).Methods Healthy male Sprague-Dawley rats were sacrificed and AEC Ⅱ were isolated,purified and incubated in 24-well culture plates (100μd/hole) with density of 1 × 106/ml.After being incubated for 2 h,the culture medium was replaced with serum-free medium DMEM.The cells were randomly divided into 4 groups (n =48 each):control group (group C),forskolin (adenylate cyclase agonist) group (group F),lidocaine 200 μg/ml group (group L),and PKA inhibitor H89 + L group (group P+ L).Forskolin 10 μmol/ml was added to DMEM in group F.Lidocaine 200 μg/ml was added to DMEM in group L.H89 10μnol/ ml was added to DMEM and AEC Ⅱ were incubated for 10 min,and then lidocaine 200 μg/ml was added in group P + L.At 6,12 and 24 h of incubation (T1-3),cAMP content and PKA activity (using ELISA),and expression of SP-A mRNA (by real-time fluorescent quantitative PCR) and SP-A (by Western blot) were measured.Results Compared with group C,the expression of SP-A mRNA and SP-A was significantly upregulated,and cAMP level and PKA activity were increased at T1-3 in group F and at T2,3 in group L.Compared with group L,the expression of SP-A and SP-A mRNA was down-regulated,PKA activity was decreased,and no significant change was found in cAMP level at T1-3 in group P + L.Conclusion Lidocaine can up-regulate the expression of SP-A in AEC Ⅱ of rats through activating cAMP-PKA signal transduction pathway. Key words: Lidocaine; Cyclic AMP; Cyclic AMP-dependent protein kinases; Epithelial cells; Pulmonary alveoli; Pulmonary surfactant-associated protein A

Effects of mechanical ventilation method on inflammatory factors and pulmonary surfactant associated protein A of bronchoalveolar lavage fluid in newborn piglets with acute lung injury

Objective To investigate the effects of 3 different ventilation methods, including conventional mechanical ventilation (CMV), high frequency oscillatory ventilation(HFOV) and partial liquid ventilation (PLV), on the changes of inflammatory factors and pulmonary surfactant associated protein A(SP-A) in bronchoalveolar lavage fluid(BALF) in newborn piglets with acute lung injury(ALI). Methods Twenty-four newborn piglets, no more than 3 days old, were enrolled.After ALI made with saline lavage(38 ℃, 35 mL/kg), newborn piglets were randomly assigned to 4 groups: control group (n=6, no ventilation), CMV group(n=6), HFOV group(n=6), and PLV group(n=6). Piglets were sacrificed after being ventilated for 24 h. Tumor necrosis factor-α(TNF-α), interleukin-8(IL-8), interleukin-1(IL-1) and SP-A in BALF were measured quantitatively by using enzyme-linked immunosorbent assay. Results In 3 groups using different ventilation methods, the population mean of TNF-α, IL-8, IL-1 and SP-A were statistically diffe-rent(all P=0.000). SP-A in PLV group and HFOV group were higher than that in CMV group (all P<0.05), while IL-8, IL-1 and TNF-α in PLV group were lower than those in CMV group (all P<0.05), IL-8 and TNF-α in PLV group were lower than those in HFOV group (all P<0.05), IL-8 and TNF-α in HFOV group were lower than those in CMV group (all P<0.05). Conclusions Pulmonary inflammatory reaction was different in 3 ventilation groups.Compared with CMV and HFOV, PLV attenuated inflammatory reaction, so it could increase the expression of SP-A and decrease the degradation of SP-A. Key words: Mechanical ventilation method; Bronchoalveolar lavage fluid; Inflammatory factor; Pulmonary surfactant associated protein A

Expression of pulmonary surfactant protein A mRNA in lungs of fetal rats with maternal intrahepatic cholestasis

Objective To investigate the pulmonary morphologic changes and pulmonary surfactant protein A (SP-A) mRNA expression in fetal rats with maternal intrahepatic cholestasis of pregnancy (ICP).Methods Animal models of intrahepatic cholestasis of pregnancy were induced by 17-α-ethinylestradiol and progesterone.Histopathologic examination of the fetal lungs was performed under light and electronic microscopes.The expression of SP-A mRNA in the fetal lungs was measured by reverse transcription-polymerase chain reaction technique.Results (1) Compared with the control group,histopathologic examination showed that fetal pulmonary tissues had dilated and congested interstitial lung capillaries,thickened alveolar septum,mild focal inflammatory exudation and focal hemorrhage in alveolus.Furthermore,reduced microvilli,mitochondrion vacuolization,cytoplasm disintegration and increased lamellar body evacuation were observed in alveolar epithelial cell II in ICP group under light and electronic microscopes.(2) Expression of SP-A mRNA in fetal lungs of ICP group (0.71 + 0.10) was significantly lower than that in control group (1.00±0.27),t=3.093,P＜0.05.Conclusions Hyperbileacidemia in ICP maternal rat might lead to pathological changes in fetal pulmonary tissues.Low expression of SP-A mRNA might contribute to lesions of fetal lung with ICP. Key words: Pregnancy complications; Cholestasis,intrahepatic; Pulmonary surfactantassociated protein A; RNA,messenger; Rats

Protective effect of calcium channel agonist BayK8644 on lungs against ischemia-reperfusion injury in rabbits

To explore the protective effect of calcium channel agonist BayK8644 preconditioning on the lungs against ischemia-reperfusion injury (I/R) and its mechanism in rabbits. Forty rabbits were randomly divided into 4 groups (10 in each group): a sham-operated group (Sham), an I/R group (I/R), an ischemic preconditioning (IP) group (IP), and a BayK8644 preconditioning group(BayK8644).The wet to dry weight (W/D) ratio, superoxide dismutase (SOD) activity, myleoperoxidase (MPO), and malondialdehyde (MDA) contents of the lung tissues were measured after the operation. Morphological and ultrastructural changes of the lung tissue were observed by light and electron microscope. The expression of pulmonary surfactant-associated protein-A (SP-A) was examined with immunohistochemistry. The W/D ratio, MPO and MDA contents of the lung tissue in the BayK8644 group and IP group were significantly lower than those in the I/R group (P<0.05), while the SOD activity and expression of SP-A of the lung tissue in the BayK8644 group and IP group were significantly higher than those in the I/R group(P<0.05), The morphological changes and ultrastructural changes were less notable in the BayK8644 group and IP group, compared with the I/R group. There was no significant difference in SOD activity, MPO and MDA contents between the BayK8644 group and IP group (P>0.05). Appropriate BayK8644 preconditioning can induce transient Ca²+ influx, and elicit strong protection against the lung ischemia-reperfusion injury, which can simulate the endogenous protective effect of ischemic preconditioning.

Protective effect of limb ischemic preconditioning on acute lung injury induced by lipopolysaccharide in rats

To explore the protective effect of noninvasive limb ischemic preconditioning (N-LIP) on acute lung injury (ALT) induced by lipopolysaccharide (LPS) in rats. Fifteen female SD rats were randomly divided into a control group, an acute lung injury group (ALI group), an acute lung injury and noninvasive limb ischemic preconditioning group (ALI+N-LIP group). After ALI rats were treated with N-LIP, the changes of airway resistance (AR) and dynamic compliance (Cdyn) were tested by invasive pulmonary function system and recorded. Blood samples and bronchoalveolar lavage fluid (BALF) were collected, the amounts of white blood cell (WBC) in BALF were counted by cytometry, and the level of lactate dehydrogenase (LDH) in BALF was also examined by automatic biochemistry analyzer. The level of serum superoxide dismutase (SOD) and malondialdehyd (MDA) was examined by chromatometry. The lung tissues were acquired to observe the expression of pulmonary surfactant-associated protein-A (SP-A) and pathological changes. After being stimulated by methacholine (Mch), the increasing rate of AR and decreasing rate of Cdyn in the ALI+N-LIP group were less than those in the ALI group (P<0.01). The levels of WBC and LDH in BALF in the ALI+N-LIP group were much lower than those in the ALI group (P<0.05). Meanwhile, the activity of serum SOD in the ALI+N-LIP group was higher, and the level of serum MDA was lower than that in the ALI group (P<0.05). The expression of SP-A in the lung tissue in the ALI+N-LIP group was the highest in the 3 groups, while that in the ALI group was the weakest (P<0.01). Injury of the lung tissue in the ALI+N-LIP group was less than that in the ALI group, but more severe than that in the control group. N-LIP has protective effect on acute lung injury induced by LPS in rats. The possible mechanism is related to improving the secretion of SP-A and antioxidation.

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

The low molecular weight heparin on rat pulmonary surfactant associated protein A of acute pulmonary embolism

To explore the effect of low molecular weight heparin (LMWH) on the changes of pulmonary surfactant associated protein A (SPA) of rats in acute pulmonary embolism. Male SD rats were injected with medical gelfoam microspheres via jugular vein to induce PE model. Rats were randomized into three groups: control group (n = 8), embolism for 2 weeks group (n = 8) and LMWH therapy group (n = 8); The LMWH therapy group were injected Nadroparin subcutaneously immediately after operation, 0.1 ml/10 kg, once every 12 h. Saline were injected into the control group instead of gelfoam granule solution without further procedure. All the rats were sacrificed at the time of 2 weeks. Pulmonary artery pressure were detected by right heart catheterization and artery blood gas were analyzed at the time of sacrifice. Lung tissue were sliced and dyed with HE to observe the embolism of pulmonary artery. Methods of RT-PCR and western blot were used to study the changes of SPA mRNA and SPA protein in lung tissue. In control group, embolism group and LMWH group, the pulmonary pressure were (14.2 +/- 4.1) mm Hg, (29.0 +/- 8.2) mm Hg, (25.50 +/- 2.74) mm Hg respectively (F3.01, P < 0.05); the artery oxygen blood pressure (PaO2) were (94.1 +/- 8.8) mm Hg, (73.4 +/- 14.3) mm Hg, (82.86 +/- 3.73) mm Hg respectively (F 1.31, P < 0.05); SPA mRNA in three groups were 1.43 +/- 0.51, 0.87 +/- 0.35, 1.07 +/- 0.20 respectively (F 2.87, P < 0.05); and SPA protein were 1.00 +/- 0.00, 0.52 +/- 0.32, 0.90 +/- 0.22 respectively (F 2.96, P < 0.05); Under microscope, lung tissue were seen congestion, edema, infiltration of inflammatory cells in embolism group, which were lessened in LMWH group. The lung SPA decrease significantly in acute pulmonary embolism, and LMWH can increase the SPA, which may be one of mechanisms of LMWH in treatment of pulmonary embolism.

Influence of ambroxol on paraquat-induced lung tissue injury and change of pulmonary surfactant-associated protein A in the experimental rats

To investigate the influence of ambroxol on paraquat poisoning induced acute lung tissue injury and the change of pulmonary surfactant associated protein A in the experimental rats. One hundred and twenty healthy adult male Sprague-Dawley rats were randomizedly assigned into normal saline (NS) group (n = 24), paraquat poisoning induced lung tissue injury model (PQ) group (n = 48) and ambroxol treatment (AT) group (n = 48). The indexes were observed among the three groups comprising the mortality rate, the change of arterial blood PaCO(2) and PaO(2), the ratio of wet to dry lung tissue (W/D), the change of the lung tissue under light and electric microscope respectively, and the expression of pulmonary surfactant associated protein A. The mortality rate of rats in the PQ group was 50.0% on the seventh day while the mortality rate in the AT group was 25.0%. The level of arterial blood PaCO(2) in the PQ group (6.94 +/- 0.8) kPa was significantly higher than that in the AT group (6.12 +/- 0.5) kPa and the NS group (4.6 +/- 0.4) kPa. The level of arterial blood PaO(2) in the PQ group (6.98 +/- 1.1) kPa was significantly lower than that in the AT group (8.25 +/- 0.7) kPa and the NS group (12.7 +/- 0.8) kPa. There were significant differences among the groups (P < 0.05). The degree of lung tissue injury was severe in PQ group and relieved in AT group. The expression of pulmonary surfactant associated protein A was significantly decreased in PQ group 13.22% +/- 2.21% on the seventh day, compared with that in the AT group (21.82% +/- 3.67%) (P < 0.05). The expression of pulmonary surfactant associated protein A in AT group was significantly higher in the AT group (18.97% +/- 0.91%) than that in the PQ group on the seventh day (P < 0.05). Ambroxol plays a role in facilitating synthesis and secretion of pulmonary surfactant protein A and relieves the lung tissue injury induced by paraquat poisoning.

Expression of Surfactant-Associated Protein A in the Fetal Rat Gastrointestinal Tract † 562

Gastrointestinal epithelium produces surface-active material closely related to that produced by pulmonary alveolar type II epithelial cells. This material includes surfactant-associated protein A (SP-A) which may play a role in gut defense mechanisms. Rubio et al. (J Biol Chem 270:12162, 1995) first demonstrated SP-A in the large and small intestines but not in the stomach of the adult rat. To ascertain the ontogeny and localization of gastrointestinal SP-A we investigated the expression of mRNA in fetal rat gut using RT-PCR with nested primers. Amplification of the cDNA yielded appropriately sized SP-A bands (372 base pairs) in the 17-day fetal rat stomach and intestine; 18-day fetal rat stomach and intestine; 20- and 21-day fetal rat stomach, small intestine and large intestine. These findings were correlated with SP-A expression in the adult rat lung as a positive control and the lack of SP-A expression in the adult rat kidney as a negative control. This is the first documentation of SP-A expression by the fetal rat gastrointestinal tract. Expression of pulmonary SP-A by the fetal rat was reported at gestational day 15.5 by in situ hybridization(Meneghetti, et al. J Histochem Cytochem 44:1173,1996) and at gestational day 13 by RT-PCR (Wang, et al. Am J Respir Cell Mol Biol 10:222, 1994). Our on-going studies are aimed at quantitative analysis of the temporal and spatial profile of SP-A expression in the rat G.I. tract and its possible role in gut defenses.

Pulmonary SP-A enhances adsorption and appears to induce surface sorting of lipid extract surfactant.

The effect of surfactant concentration and supplementation with surfactant-associated protein A (SP-A) on the surface activity of lipid extract surfactant (LES) was examined using a captive bubble technique. Adsorption of LES is strongly concentration dependent over the range of 50-1,000 micrograms/ml. Addition of SP-A to LES at low concentrations in the presence of calcium dramatically increases the rate of adsorption. In quasistatic cycling experiments, samples containing SP-A require less compression to achieve low surface tensions even during the first compression cycle. Calculated film compressibilities at 15 mN/m indicate that SP-A alters the surfactant monolayer behavior such that in a small number of cycles the compressibility is indistinguishable from that of pure DPPC. Furthermore, SP-A reduces the incidence of bubble "clicking," suggesting a stabilization of the monolayer at low surface tensions. In dynamic cycling experiments, SP-A reduces compression of the film area required to achieve a low surface tension of approximately 1 mN/m. SP-A eliminated the plateau just below 25 mN/m normally observed during the compression phase with low concentrations of LES and the shoulder observed at approximately 35 mN/m during expansion. In the presence of SP-A and, to a lesser extent with high concentrations of LES, there is a marked lag in the increase in surface tension during the initial part of the dynamic expansion loop, with surface tensions remaining near 1 mN/m for approximately 10% of the increase in bubble area. The results indicate that SP-A enhances phospholipid adsorption during dynamic cycling and may enhance elimination of non-DPPC lipids during cycling.(ABSTRACT TRUNCATED AT 250 WORDS)