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.

Diagnosis of asphyxiation in advanced decomposed corpses by using Oil-Red-O Stain and immunohistochemical technology

BackgroundThe unambiguous diagnosis of asphyxiation is still a major challenge for the forensic pathologist, especially in terms of highly advanced decomposed corps. MethodologyIn order to demonstrate asphyxiation particularly in profoundly putrid bodies we hypothesized that hypoxic stress is basically responsible for generalized fatty degeneration of visceral organs which can be detected by histological examination using a special staining technique referred to as Oil-Red-O Stain (Sudan III-red-B-stain). To test this hypothesis we examined different tissues (myocardium, liver, lung and kidney) of 107 people divided into 5 groups. These are: (i) 71 case-victims who were found in a truck and died most likely due to asphyxiation, whereby any other violent or natural cause of death was ruled out by postmortem examination; (ii) 10 barely decomposed positive-control-victims; (iii) 6 non-decomposed positive-control-victims; iv) 10 drowning non-decomposed positive-control victims, and v) 10 negative-control-victims. Apart from general histological special staining methods, an immunohistochemically approach as a case-control-study on lung tissues of same individuals was carried out by means of using two polyclonal rabbit-antibodies against (i) HIF-1-α (Hypoxia Inducing Factor-1 alpha) and (ii) SP-A (pulmonary surfactant-associated protein A) to detect both the transcription factor and pulmonary surfactants. The positive proof of already either of them gives evidence of death caused by hypoxia. ResultsHistological examination of myocardium, liver and kidney of the 71 case-victims and the 10 positive-control-victims using Oil-Red-O Stain showed a fatty degeneration of small droplet type; there was no evidence for fatty degeneration in tissues of the 10 negative-control-victims. These findings strongly indicate a causal association between oxygen deficiency and generalized fatty degeneration of viscera due to insufficient oxygen supply. In terms of methodology, this special staining technique seems to be very informative, even applicable on decomposed corps. Results of immunohistochemistry indicate that on the one hand the detection of HIF-1α is not possible to perform on (advanced) putrid bodies, whereas the verification of SP-A is still feasible on the other. ConclusionPositive Oil-Red-O staining and the immunohistochemical detection of SP-A can serve as a serious hint for the diagnosis of asphyxia on putrid corpses, considering other circumstances of death that have been determined.

The protective effect of high heme oxygenase-1 expression induced by propofol on the alveolar II type epithelial cells of rats with acute lung injury induced by oleic acid.

This study aimed to investigate the mechanism of propofol (PR) pretreatment inducing high heme oxygenase-1 (HO-1) expression to protect alveolar type II epithelial cells (AEC-II) in rats with acute lung injury (ALI) induced by oleic acid (OA). In this study, 32 male Sprague-Dawley rats (250 - 300 g) were randomly divided into four groups (n = 8 in each group) as follows: group C (the normal control group), the OA group (the oleic acid injury control group), the OA + PR group (the PR pretreatment group), and the OA + IX group (the zinc porphyrin IX pretreatment group). Arterial blood gases, bronchoalveolar lavage fluid (BALF), and serum pulmonary surfactant-associated protein A (SP-A) were measured in each group. The changes in the AEC-II ultrastructure were observed under an electron microscope. The HO-1 protein expression was detected by immunohistochemistry, and HO-1 messenger ribonucleic acid (mRNA) was detected by polymerase chain reaction. The results of this study showed that there were significant differences in PO2, pCO2, and PaO2/FiO2 among the different groups (p < 0.05). The difference between BALF and SP-A in each group was statistically significant (p < 0.01). There were also significant differences in the integrated optical density of the HO-1 protein expression and HO-1 mRNA in the pulmonary tissue of the different groups (p < 0.05 or p < 0.01). The results of the electron microscopy showed that AEC-II were relatively irregular in the OA group. The cells degenerated and even disintegrated, the microvilli on the cell surface decreased, the lamellar bodies in the cytoplasm were evacuated, and some were discharged into the alveolar cavity. The above-mentioned changes in the OA + PR group were lower than in the OA group, while the changes were greater in the OA + IX group, compared with those in the OA group. We conclude that PR can significantly increase the expression of HO-1 in pulmonary tissues and reduce pulmonary injury, and, therefore, protect the AEC-II.

The effect of ultrasound-guided intraperitoneal injection of ulinastatin on lung development in intrauterine growth-restricted fetal rabbits

Objectives To investigate the effect and mechanism of ulinastatin (UTI) on development of lungs in fetal rabbits with intrauterine growth retardation (IUGR). Methods Twenty pregnant rabbits were equally divided into normal, IUGR, UTI, and LY groups. The normal group was only injected with saline and marked with tattoo ink. IUGR models were established by injecting N-nitro-L-arginine methyl ester in the rabbits of IUGR, UTI, and LY groups. The three groups were injected with saline, UTI, or UTI + LY294002 (PI3K inhibitor) respectively, and then marked with tattoo ink. After cesarean section, neonatal weights, and levels of dipalmitoyl phosphatidylcholine (DPPC), nitric oxide (NO), P-Akt, P-eNOS, and pulmonary surfactant-associated protein A (SP-A) were determined in tissues of the lungs. Radial alveoli count (RAC), pulmonary interstitial ratio, and ultrastructural changes in type II alveolar epithelial cells (AEC II) were also determined through light and electron microscopy. Results Compared with control, the IUGR group showed significantly decreased weight, RAC, lamellar bodies in AEC II, and levels of P-Akt, P-eNOS, DPPC, NO, and SP-A, and increased pulmonary interstitial ratio (p < .05). The UTI treatment did not affect the weight; however, all other parameters were opposite to those observed in the IUGR group (p < .05). Furthermore, these UTI-mediated changes were inhibited by LY294002. Conclusions Intraperitoneal UTI injection can promote the development of lungs and increase pulmonary surfactant production in IUGR fetal rabbits, potentially by activating PI3K/Akt/eNOS/NO signaling.

GW29-e0814 Genetic polymorphisms of pulmonary surfactant-associated protein A gene may be potential risk factors of severe obstructive sleep apnea

Decreased circulating surfactant protein A (SP-A) was observed in some individuals with higher hypopnea index (HI) in obstructive sleep apnea (OSA) in previous study, the present study aimed to further explore the role of pulmonary surfactant-associated protein A (SFTPA) gene in OSA. In this case-

Effects of aerosol inhalation of recombinant human keratinocyte growth factor 2 on the lung tissue of rabbits with severe smoke inhalation injury

Objective: To investigate the effect of recombinant human keratinocyte growth factor 2 (rhKGF-2) on lung tissue of rabbits with severe smoke inhalation injury. Methods: A total of 120 New Zealand rabbits were divided into 5 groups by random number table after being inflicted with severe smoke inhalation injury, with 24 rats in each group. Rabbits in the simple injury group inhaled air, while rabbits in the injury+phosphate buffer solution (PBS) group inhaled 5 mL PBS once daily for 7 d. Rabbits in injury+1 mg/kg rhKGF-2 group, injury+2 mg/kg rhKGF-2 group, and injury+5 mg/kg rhKGF-2 group received aerosol inhalation of 1 mg/kg, 2 mg/kg, and 5 mg/kg rhKGF-2 (all dissolved in 5 mL PBS) once daily for 7 d, respectively. On treatment day 1, 3, 5, and 7, blood samples were taken from the ear central artery of 6 rabbits in each group. After the blood was taken, the rabbits were sacrificed, and the tracheal carina tissue and lung were collected. Blood pH value, arterial oxygen partial pressure (PaO(2)), arterial blood carbon dioxide pressure (PaCO(2)), and bicarbonate ion were detected by handheld blood analyzer. The expressions of pulmonary surfactant-associated protein A (SP-A) and vascular endothelial growth factor (VEGF) in lung tissue were detected by Western blotting. Pathomorphology of lung tissue and trachea was observed by hematoxylin-eosin staining. Data were processed with analysis of variance of two-way factorial design and Tukey test. Results: (1) Compared with those in simple injury group, the blood pH values of rabbits in the latter groups on treatment day 1-7 had no obvious change (P>0.05). The PaO(2) of rabbits in injury+2 mg/kg rhKGF-2 group on treatment day 5 and 7 were (75.0±2.4) and (71.0±4.5) mmHg (1 mmHg=0.133 kPa), respectively, which were significantly higher than (62.0±6.8) and (63.0±3.0) mmHg in simple injury group (q=4.265, 8.202, P 0.05). The expressions of SP-A in lung tissue of rabbits in injury+2 mg/kg rhKGF-2 group and injury+5 mg/kg rhKGF-2 group on treatment day 3 were 0.091±0.007 and 0.101±0.009, respectively, significantly higher than 0.069±0.009 in simple injury group (q=10.800, 13.580, P 0.05). Compared with those in simple injury group, the expressions of VEGF in lung tissue of rabbits in injury+2 mg/kg rhKGF-2 group on treatment day 3 and 7 were significantly increased (q=4.243, 8.000, P<0.05 or P<0.01), and the expression of VEGF in lung tissue of rabbits in injury+5 mg/kg rhKGF-2 group on treatment day 7 was significantly increased (q=20.720, P<0.01). (4) On treatment day 1, the injury of rabbits in each group was similar, with a large number of neutrophils infiltrated and abscess formed in the alveolar and interstitial tissue, thickened alveolar septum, some collapsed alveolar and atelectasis; large area of tracheal mucosa was degenerated and necrotic, with a large amount of inflammatory exudates blocking in the cavity. On treatment day 3, the inflammation of lung tissue and trachea in each group were improved, but the inflammation in simple injury group and injury+PBS group was also serious. On treatment day 5, the inflammation in lung tissue and trachea of rabbits in injury+2 mg/kg rhKGF-2 group and injury+5 mg/kg rhKGF-2 group were improved much obviously than those in the other groups. On treatment day 7, the inflammation in lung tissue of rabbits in injury+5 mg/kg rhKGF-2 group alleviated obviously than those in the other groups, most alveoli had no obvious exudative fluid, the alveolar cavity was intact and clear, the local alveolar dilated like a cyst, and the alveolar septum thinning; the improvement of inflammation of trachea was more obvious than the other groups, the tracheal mucosa tended to be more complete, and few neutrophils were infiltrated in the endotracheal cavity. Conclusions: Atomization inhalation of rhKGF-2 can improve the PaO(2) level of rabbits with severe smoke inhalation injury, reduce airway inflammation, increase the expression of SP-A and VEGF in lung tissue, thus promoting the repair of lung tissue.

Evaluation of pulmonary reexpansion in a porcine model of bronchial foreign body.

This study was designed to establish a porcine model of reversible obstruction of endobronchial foreign body (FB) and to assess the natural pulmonary reexpansion process using radiology and histopathology after removal of the bronchial FB. A metal stent was placed in the right lower lobe bronchial lumen of 15 pigs by bronchoscopy and removed after 2 weeks of stent retention. Animals were divided into two groups (group I and II), based on when they were sacrificed (week 2 or week 4) after stent removal. Pigs underwent computerized tomography scan to document pulmonary radiological changes. The lungs were harvested for electron microscopy examination, and the expression of pulmonary surfactant-associated protein A (SPA) was determined by immunohistochemistry. Thirteen (86.7%) animals successfully responded to the intervention. Atelectasis was formed by stent implantation within 2 weeks. The ratio of the residual atelectasis area was smaller in group II compared to that in group I (P < 0.01). The histological manifestations of experimental lungs were significantly improved in group II. Moreover, the expression of SPA in group II was higher compared to that in group I (P < 0.01). We have established a model of reversible bronchial FB obstruction in pigs that is both feasible and appropriate for evaluating the long-term process of pulmonary reexpansion after removal of FB. Bronchial metal FB retention for a period of 2 weeks could form atelectasis, and a natural pulmonary recovery process related to atelectasis takes approximately 4 weeks after removal of metal FB.

Angiotensin-Converting Enzyme 2 Attenuates Bleomycin-Induced Lung Fibrosis in Mice

Background: Local renin-angiotensin system (RAS) activation has been shown to play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). It has been reported that angiotensin-converting enzyme 2 (ACE2) could inhibit RAS-mediated epithelial injury and fibrogenesis and that ACE2 deficiency could aggravate acute and chronic lung injury. Through research, it could be deduced that ACE2 could protect against pulmonary fibrosis as a therapeutic target. Methods: Time-course analysis of the pathological characteristics of bleomycin-induced lung fibrosis was undertaken in a mouse model, and the effect of exogenous ACE2 on lung fibrosis was studied. Immunohistchemistry (IHC) staining and western blot (WB) testing for AGT and ACE2 were performed to evaluate the regulation of local RAS. TUNEL staining was used to observe epithelial apoptosis. Leukocyte common antigen (LCA) and pulmonary surfactant-associated protein A (SP-A) IHC staining and WB testing were performed to assess the inflammatory response and epithelial regeneration. Masson's staining and a hydroxyproline assay were performed to examine collagen deposition. IHC staining and WB testing for TGF-β1 and α-SMA were performed to investigate the regulation of pro-fibrotic cytokines and the activation of fibroblasts. Results: Exogenous ACE2 attenuated bleomycin-induced lung fibrosis by reversing the reduction of local ACE2 and by suppressing the elevation of AGT. ACE2 decreased the apoptosis index and LCA levels and ameliorated the dynamic change in SP-A level, thus protecting against epithelial injury. Reductions of TGF-β1 and α-SMA were also found in ACE2-treated mice, indicating the inhibition of fibrogenesis. Conclusion: ACE2 attenuated bleomycin-induced lung fibrosis as an anti-inflammatory anti-apoptotic and anti-fibrotic agent, and it might be a promising therapeutic target for IPF.

Effect of autologous blood withdrawal-reinfusion on pulmonary function in patients undergoing spinal surgery

Objective To evaluate the effect of autologous blood withdrawal-reinfusion on pulmonary function in the patients undergoing spinal surgery.Methods Forty patients of both sexes,aged 28-64 yr,with body mass index 20-25 kg/m2,of ASA physical status Ⅰ or Ⅱ,scheduled for elective spinal surgery under general anesthesia,were randomly divided into 2 groups (n =20 each):allogeneic blood transfusion group (group A) and autologous blood withdrawal-reinfusion group (group B).Anesthesia was induced with iv midazolam,sufentanil,propofol and rocuronium,and maintained with propofol,remifentanil and cisatracurium.Patients were tracheally intubated and mechanically ventilated.Patients received transfusion of allogeneic blood in group A,while patients received transfusion of intraoperative salvaged blood in group B.Immediately before blood transfusion (T0,baseline),and at l,6 and 24 h after the last transfusion during operation (T1-3),blood samples were collected from the radial artery for blood gas analysis and for measurement of serum pulmonary surfactant-associated protein A (SP-A) level.Oxygenation index (OI) and respiratory index (RI) were calculated.Adverse effects of blood transfusion and respiratory complications within 72 h after operation were also recorded.Results No significant differences were found in all the parameters mentioned above at each time point between the two groups,and these parameters were all within the normal range.Compared with the baseline values at T0,OI was significantly decreased and RI was increased at T1,2,and the serum SP-A level was decreased at T2,3 in the two groups.Compared with the value at T1,RI was significantly decreased at T3,the serum SP-A level was decreased at T2-3,and no significant changes were found in OI in the two groups.No adverse effects of blood transfusion were found in the two groups.There were no respiratory complications within 72 h after operation in group A,one case developed respiratory complications within 72 h after operation in group B,and no differences were found between the two groups.Conclusion Autologous blood withdrawal-reinfusion exerts no effect on pulmonary function in the patients undergoing spinal surgery. Key words: Blood transfusion, autologous; Respiratory function tests; Blood loss, surgical

Establishment of surfactant-associated protein A suicide gene system and analysis of its activity.

Alveolar epithelial type II (AT II) cells are essential for lung development and remodeling, as they are precursors for type I cells and also produce other non-repair cells (fibroblasts). Progenitor cells are believed to possess capability of multi-potent transdifferentiation, which is closely related to the niche, suggesting the importance of establishment of a lung progenitor cell niche model. We hypothesized that pulmonary surfactant-associated protein A (SPA) suicide gene system would cause AT II cell to kill itself through apoptosis and leave its niche. In vitro, the recombinant adeno-associated virus vectors-SPA-thymidine kinase (rAAV-SPA-TK) system was established to get targeted apoptotic AT II cells. The apoptosis of AT II cells was detected by using MTT. The results showed that cloned SPA gene promoter had specific transcriptional activity in SPA high expression cells, and SPA high expression cells (H441) transfected with TK gene had higher sensitivity to ganciclovir (GCV) than SPA low expression cells (A549). In vivo, increased apoptosis of AT II cells induced by GCV in rAAV-SPA-TK system was observed by TUNEL. Finally, the successful packaging and application of rAAV-SPA-TK system provide experimental basis to get specific lung progenitor cell (AT II) niche in vitro and in vivo.

Regulation of transplanted mesenchymal stem cells by the lung progenitor niche in rats with chronic obstructive pulmonary disease

BackgroundStem cell transplantation is a promising method for the treatment of chronic obstructive pulmonary disease (COPD), and mesenchymal stem cells (MSCs) have clinical potential for lung repair/regeneration. However, the rates of engraftment and differentiation are generally low following MSC therapy for lung injury. In previous studies, we constructed a pulmonary surfactant-associated protein A (SPA) suicide gene system, rAAV-SPA-TK, which induced apoptosis in alveolar epithelial type II (AT II) cells and vacated the AT II cell niche. We hypothesized that this system would increase the rates of MSC engraftment and repair in COPD rats.MethodsThe MSC engraftment rate and morphometric changes in lung tissue in vivo were investigated by in situ hybridization, hematoxylin and eosin staining, Masson’s trichrome staining, immunohistochemistry, and real-time PCR. The expression of hypoxia inducible factor (HIF-1α) and stromal cell-derived factor-1 (SDF-1), and relationship between HIF-1α and SDF-1 in a hypoxic cell model were analyzed by real-time PCR, western blotting, and enzyme-linked immunosorbent assay.ResultsrAAV-SPA-TK transfection increased the recruitment of MSCs but induced pulmonary fibrosis in COPD rats. HIF-1α and SDF-1 expression were enhanced after rAAV-SPA-TK transfection. Hypoxia increased the expression of HIF-1α and SDF-1 in the hypoxic cell model, and SDF-1 expression was augmented by HIF-1α under hypoxic conditions.ConclusionsVacant AT II cell niches increase the homing and recruitment of MSCs to the lung in COPD rats. MSCs play an important role in lung repair and promote collagen fiber deposition after induction of secondary damage in AT II cells by rAAV-SPA-TK, which involves HIF-1α and SDF-1 signaling.

Genotype–phenotype correlation in Chinese patients with pulmonary mixed type adenocarcinoma: Relationship between histologic subtypes, TITF-1/SP-A expressions and EGFR mutations

This study aimed to explore the association between adenocarcinoma-related morphological and molecular characteristics and EGFR mutations in Chinese lung adenocarcinomas. A total of 139 consecutively resected pulmonary adenocarcinoma patients were screened for EGFR mutations by the amplification refractory mutation system assay. For the resected specimens, histologic subtypes were sub-classified using either the 2004 WHO classification or the 2011 IASLC/ATS/ERS classification. Meanwhile, TITF-1 (thyroid transcription factor 1) and SP-A (surfactant-associated protein A) immunohistochemistry staining was also detected. The results were correlated with EGFR mutations and clinicopathological features mentioned above. Both sub-classification methods reflected differences in frequencies of EGFR mutations in lung adenocarcinoma subtypes. In summary, mixed non-mucinous bronchioloalveolar carcinoma (BAC) or papillary components and papillary predominant adenocarcinoma showed a higher frequency of EGFR mutations than mucinous BAC components; Also, EGFR mutations were significantly more common in tumors with TITF-1 or SP-A expressions than in those without (p=0.002, p=0.026), especially the sensitivity of TITF-1 (96.9%) and the negative predictive value of TITF-1 (88.2%). Our data further showed significant genotype–phenotype correlations between EGFR mutations and adenocarcinoma-related morphological and molecular characteristics, and patients with special histologic and IHC staining features might have higher EGFR mutation rates. In addition, this study, for the first time, indicated the significant relationship between SPA IHC and EGFR mutations, which needed confirmation by further research.

Expression profiling of abundant genes in pulmonary and cardiac muscle tissues of Tibetan Antelope (Pantholops hodgsonii)

The Tibetan Antelope (TA), which has lived at high altitude for millions of years, was selected as the model species of high hypoxia-tolerant adaptation. Here we constructed two cDNA libraries from lung and cardiac muscle tissues, obtained EST sequences from the libraries, and acquired extensive expression data related energy metabolism genes. Comparative analyses of synonymous (Ks) and nonsynonymous (Ka) substitution rates of nucleus-encoded mitochondrial unigenes among different species revealed that many antelope genes have undergone rapid evolution. Surfactant-associated protein A (SP-A) and surfactant-associated protein B (SP-B) genes in the AT lineage experienced accelerated evolution compared to goat and sheep, and these two genes are highly expressed in the lung tissue. This study suggests that many specific genes of lung and cardiac muscle tissues showed unique expression profiles and may undergo fast adaptive evolution in TA. These data provide useful information for studying on molecular adaptation to high-altitude in humans as well as other mammals.

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

Surfactant Protein A in Cystic Fibrosis: Supratrimeric Structure and Pulmonary Outcome

BackgroundThe state of oligomerization of surfactant associated protein-A (SP-A) monomers differs between individuals. This likely affects SP-A’s functional properties and could thereby influence clinical status in patients with lung diseases. In this study we focus on SP-A structure in cystic fibrosis (CF) compared to both healthy subjects and disease controls.MethodsSP-A composition and function were assessed in both bronchoalveolar lavage (BAL) fluid and serum of 46 CF patients with mild disease, 25 patients with chronic bronchitis and 22 healthy subjects by gel chromatography and a functional agglutination assay. Relation of SP-A agglutination ability to disease severity of the subjects was explored.ResultsSP-A was present in seven major oligomeric forms with the majority of SP-A being structurally organized as complex oligomeric forms. More complex oligomeric forms were associated with better SP-A function with regard to its agglutination ability. These forms were more frequently observed in BAL than in serum, but there were no differences between disease groups. In CF patients, more complex forms of SP-A were associated with better lung function.ConclusionsOrganizational structure of SP-A affects its functional activity and is linked to disease severity in CF.

The Interplay of Lung Surfactant Proteins and Lipids Assimilates the Macrophage Clearance of Nanoparticles

The peripheral lungs are a potential entrance portal for nanoparticles into the human body due to their large surface area. The fact that nanoparticles can be deposited in the alveolar region of the lungs is of interest for pulmonary drug delivery strategies and is of equal importance for toxicological considerations. Therefore, a detailed understanding of nanoparticle interaction with the structures of this largest and most sensitive part of the lungs is important for both nanomedicine and nanotoxicology. Astonishingly, there is still little known about the bio-nano interactions that occur after nanoparticle deposition in the alveoli. In this study, we compared the effects of surfactant-associated protein A (SP-A) and D (SP-D) on the clearance of magnetite nanoparticles (mNP) with either more hydrophilic (starch) or hydrophobic (phosphatidylcholine) surface modification by an alveolar macrophage (AM) cell line (MH-S) using flow cytometry and confocal microscopy. Both proteins enhanced the AM uptake of mNP compared with pristine nanoparticles; for the hydrophilic ST-mNP, this effect was strongest with SP-D, whereas for the hydrophobic PL-mNP it was most pronounced with SP-A. Using gel electrophoretic and dynamic light scattering methods, we were able to demonstrate that the observed cellular effects were related to protein adsorption and to protein-mediated interference with the colloidal stability. Next, we investigated the influence of various surfactant lipids on nanoparticle uptake by AM because lipids are the major surfactant component. Synthetic surfactant lipid and isolated native surfactant preparations significantly modulated the effects exerted by SP-A and SP-D, respectively, resulting in comparable levels of macrophage interaction for both hydrophilic and hydrophobic nanoparticles. Our findings suggest that because of the interplay of both surfactant lipids and proteins, the AM clearance of nanoparticles is essentially the same, regardless of different intrinsic surface properties.

Serum pneumoproteins in firefighters

Serum Clara cell protein (CC16) and surfactant-associated protein A (SP-A) were measured in a cross-sectional study in 402 firefighters. For the population as a whole, no associations were detected between serum pneumoproteins and smoke exposure. SP-A levels were increased in symptomatic subjects exposed to fire smoke within 2 days before testing. SP-A levels were higher after an inhalation incident ever. CC16 was negatively associated with the number of fires fought in the last 12 months in current nonsmokers. These associations between pneumoprotein levels reiterate the importance of adequate use of self-contained breathing apparatus by firefighters.

Troglitazone-activated PPARγ inhibits LPS-induced lung alveolar type II epithelial cells injuries via TNF-α

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) are common syndromes characterized by diffuse, acute injury to the alveolar epithelium and pulmonary vascular endothelial cells, with high mortality rate for there are no effective pharmacological therapies. Peroxisome proliferators-activated receptor γ (PPARγ), a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors, is ubiquitously expressed within the lung. Recent studies have indicated PPARγ can protect lung tissue and alleviate pulmonary inflammatory injury. But no studies examined whether PPARγ agonists can protect the alveolar epithelial cells cultured in vitro. We observed the protective effect of PPARγ in LPS-induced alveolar type II epithelial cells injury. The results showed troglitazone-activated PPARγ could inhibit the production of TNF-α, one of the most important inflammatory factors, and then increased the expression of surfactant-associated protein A (SP-A) and attenuate the apoptosis of alveolar type II epithelial cells. Our results suggest that PPARγ may have a potential therapeutic effect on ALI.

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.