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Rationale: Several common and rare genetic variants have been associated with idiopathic pulmonary fibrosis, a progressive fibrotic condition that is localized to the lung. Objectives: To develop an integrated understanding of the rare and common variants located in multiple loci that have been reported to contribute to the risk of disease. Methods: We performed deep targeted resequencing (3.69 Mb of DNA) in cases (n = 3,624) and control subjects (n = 4,442) across genes and regions previously associated with disease. We tested for associations between disease and 1) individual common variants via logistic regression and 2) groups of rare variants via sequence kernel association tests. Measurements and Main Results: Statistically significant common variant association signals occurred in all 10 of the regions chosen based on genome-wide association studies. The strongest risk variant is the MUC5B promoter variant rs35705950, with an odds ratio of 5.45 (95% confidence interval, 4.91-6.06) for one copy of the risk allele and 18.68 (95% confidence interval, 13.34-26.17) for two copies of the risk allele (P = 9.60 × 10-295). In addition to identifying for the first time that rare variation in FAM13A is associated with disease, we confirmed the role of rare variation in the TERT and RTEL1 gene regions in the risk of IPF, and found that the FAM13A and TERT regions have independent common and rare variant signals. Conclusions: A limited number of common and rare variants contribute to the risk of idiopathic pulmonary fibrosis in each of the resequencing regions, and these genetic variants focus on biological mechanisms of host defense and cell senescence.

Alveolar epithelium plays a pivotal role in protecting the lungs from inhaled infectious agents. Therefore, the regenerative capacity of the alveolar epithelium is critical for recovery from these insults in order to rebuild the epithelial barrier and restore pulmonary functions. Here, we show that sublethal infection of mice with Streptococcus pneumoniae, the most common pathogen of community-acquired pneumonia, led to exclusive damage in lung alveoli, followed by alveolar epithelial regeneration and resolution of lung inflammation. We show that surfactant protein C-expressing (SPC-expressing) alveolar epithelial type II cells (AECIIs) underwent proliferation and differentiation after infection, which contributed to the newly formed alveolar epithelium. This increase in AECII activities was correlated with increased nuclear expression of Yap and Taz, the mediators of the Hippo pathway. Mice that lacked Yap/Taz in AECIIs exhibited prolonged inflammatory responses in the lung and were delayed in alveolar epithelial regeneration during bacterial pneumonia. This impaired alveolar epithelial regeneration was paralleled by a failure to upregulate IκBa, the molecule that terminates NF-κB-mediated inflammatory responses. These results demonstrate that signals governing resolution of lung inflammation were altered in Yap/Taz mutant mice, which prevented the development of a proper regenerative niche, delaying repair and regeneration of alveolar epithelium during bacterial pneumonia.

BackgroundMutations in the NK2 homeobox 1 (NKX2-1) gene are associated with lung disease in infants and children. We hypothesize that disruption of normal surfactant gene expression with these mutations contributes to the respiratory phenotypes observed.MethodsTo assess transactivational activity, cotransfection of luciferase reporter vectors containing surfactant protein B or C (SFTPB or SFTPC) promoters with NKX2-1 plasmids was performed and luciferase activity was measured. To assess the binding of mutated proteins to target DNA, electrophoretic mobility shift assays (EMSA) were performed using nuclear protein labeled with oligonucleotide probes representing NKX2-1 consensus binding sequences followed by gel electrophoresis. The effect of overexpression of wild-type (WT) and mutant NKX2-1 on SFTPB and SFTPC was evaluated with quantitative real-time PCR.ResultsDecreased transactivation of the SFTPB promoter by both mutants and decreased transactivation of the SFTPC promoter by the L197P mutation was observed. EMSA demonstrated decreased DNA binding of both mutations to NKX2-1 consensus binding sequences. Transfection of A549 cells with NKX2-1 expression vectors demonstrated decreased stimulation of SFTPB and SFTPC expression by mutant proteins compared with that of WT.ConclusionDisruption of transcriptional activation of surfactant protein genes by these DNA-binding domain mutations is a plausible biological mechanism for disruption of surfactant function and subsequent respiratory distress.

The transgenic mouse strains surfactant protein C-reverse tetracycline transactivator (SP-C-rtTA), club cell secretory protein (CCSP)-rtTA, and tetracycline operator (TetO)-Cre have been invaluable for spatiotemporally regulating gene deletion in the pulmonary epithelium. In this study, we measured the efficiency and specificity of gene deletion that can be achieved in these mice using the Rosa26-eYFP reporter. Triple-transgenic mice (tTg or rtTA/TetO-Cre/Rosa-eYFP) were bred and treated with various doxycycline (dox) regimens to induce gene deletion, which was then quantified in various cell populations by flow cytometry. In these crosses, we found that the TetO-Cre transgene must be transmitted through the female parent to avoid germline gene deletion. With dox exposure during lung development, SP-C-tTg mice deleted in ∼65-75% of alveolar epithelial type II (ATII) cells, but in only ∼45-50% of the integrin β4+ population, which consisted of club cells and distal lung progenitor cells. In contrast, CCSP-tTg mice deleted in ∼50% of ATII cells and ∼80% of integrin β4+ cells. Upon dox treatment of adults, deletion in ATII cells and integrin β4+ cells in SP-C-tTg mice dropped significantly to ∼20% and ∼6%, respectively, whereas CCSP-tTg mice deleted in ∼57% of ATII and ∼40% of integrin β4+ cells. Interestingly, untreated CCSP-tTg mice also deleted in ∼40% of integrin β4+ cells, indicating significant leakiness of CCSP-tTg in β4+ cells. In all mouse groups, minimal deletion occurred in mouse tracheal epithelial cells or in mesenchymal or hematopoietic cells. These data provide the first quantitative, side-by-side comparison of the deletion efficiency for these widely used transgenic mouse strains.

BackgroundMonoallelic mutations of the Surfactant Protein C gene (SFTPC) are associated with Interstitial Lung Disease in children. I73T is the most common mutation, accounting for 30 % of all cases reported.Case presentationWe describe three patients carrying the same I73T SPC mutation with very different phenotypes, clinical course (ranging from mild respiratory symptoms to death for respiratory failure) and outcome.ConclusionsThe disease mechanisms associated with SP-C mutations suggest that the combination of individual genetic background and environmental factors contribute largely to the wide variability of clinical expression. Infants, children and adults with ILD of unknown etiology should be investigated for SP-C genetic abnormalities.

The article discusses the results of a study on transplantation of several types of progenitor cells of the mouse lungs. Topics mentioned include the comparison of the lung injury models and orthotopic delivery assay, the expression of the airway or alveolar surfactant protein C epithelial cell markers, and the use of preconditioning culture conditions.

Successful recovery from lung injury requires the repair and regeneration of alveolar epithelial cells to restore the integrity of gas-exchanging regions within the lung and preserve organ function. Improper regeneration of the alveolar epithelium is often associated with severe pulmonary fibrosis, the latter of which involves the recruitment and activation of fibroblasts, as well as matrix accumulation. Type 2 alveolar epithelial cells (AEC2s) are stem cells in the adult lung that contribute to the lung repair process. The mechanisms that regulate AEC2 renewal are incompletely understood. We provide evidence that expression of the innate immune receptor Toll-like receptor 4 (TLR4) and the extracellular matrix glycosaminoglycan hyaluronan (HA) on AEC2s are important for AEC2 renewal, repair of lung injury and limiting the extent of fibrosis. Either deletion of TLR4 or HA synthase 2 in surfactant-protein-C-positive AEC2s leads to impaired renewal capacity, severe fibrosis and mortality. Furthermore, AEC2s from patients with severe pulmonary fibrosis have reduced cell surface HA and impaired renewal capacity, suggesting that HA and TLR4 are key contributors to lung stem cell renewal and that severe pulmonary fibrosis is the result of distal epithelial stem cell failure.

Genetic defects of surfactant metabolism are associated with a broad range of clinical manifestations, from neonatal respiratory distress syndrome to adult interstitial lung disease. Early therapies may improve symptoms but diagnosis is often delayed owing to phenotype and genotype variability. Our objective was to characterize the cellular/ultrastructural correlates of surfactant protein C (SP-C) mutations in children with idiopathic diffuse lung diseases. We sequenced SFTPC - the gene encoding SP-C - SFTPB and ABCA3, and analyzed morphology, ultrastructure and SP expression in lung tissue when available. We identified eight subjects who were heterozygous for SP-C mutations. Median age at onset and clinical course were variable. None of the mutations were located in the mature peptide-encoding region, but were either in the pro-protein BRICHOS or linker C-terminal domains. Although lung morphology was similar to other genetic surfactant metabolism disorders, electron microscopy studies showed specific anomalies, suggesting surfactant homeostasis disruption, plus trafficking defects in the four subjects with linker domain mutation and protein misfolding in the single BRICHOS mutation carrier in whom material was available. Immunolabeling studies showed increased proSP-C staining in all cases. In two cases, amyloid deposits could be identified. Immunochemistry and ultrastructural studies may be useful for diagnostic purposes and for genotype interpretation.

Background and Objective: Variants in surfactant genes SFTPC or ABCA3 are responsible for interstitial lung disease (ILD) in children and adults, with few studies in adults., Methods: We conducted a multicentre retrospective study of all consecutive adult patients diagnosed with ILD associated with variants in SFTPC or ABCA3 in the French rare pulmonary diseases network, OrphaLung. Variants and chest computed tomography (CT) features were centrally reviewed., Results: We included 36 patients (median age: 34 years, 20 males), 22 in the SFTPC group and 14 in the ABCA3 group. Clinical characteristics were similar between groups. Baseline median FVC was 59% ([52-72]) and DLco was 44% ([35-50]). An unclassifiable pattern of fibrosing ILD was the most frequent on chest CT, found in 85% of patients, however with a distinct phenotype with ground-glass opacities and/or cysts. Nonspecific interstitial pneumonia and usual interstitial pneumonia were the most common histological patterns in the ABCA3 group and in the SFTPC group, respectively. Annually, FVC and DL CO declined by 1.87% and 2.43% in the SFTPC group, respectively, and by 0.72% and 0.95% in the ABCA3 group, respectively (FVC, p = 0.014 and DL CO , p = 0.004 for comparison between groups). Median time to death or lung transplantation was 10 years in the SFTPC group and was not reached at the end of follow-up in the ABCA3 group., Conclusion: SFTPC and ABCA3-associated ILD present with a distinct phenotype and prognosis. A radiologic pattern of fibrosing ILD with ground-glass opacities and/or cysts is frequently found in these rare conditions., (© 2024 The Authors. Respirology published by John Wiley & Sons Australia, Ltd on behalf of Asian Pacific Society of Respirology.)

The article described accumulation of crystals in alveolar macrophages from Surfactant Protein C (SP-C)–deficient mice during aging. Topics include the crystal inclusions present in alveolar macrophages do not have striations typical of intracellular collagen fibrils; and alveolar macrophages not be simply spectators of lung diseases such as fibrotic remodeling.

Type II alveolar epithelial cells (AEC2s) play an essential role in the function and maintenance of the pulmonary epithelium. Several transgenic mice have been developed to study the function of these cells in vivo by using the human SFTPC promoter to drive expression of Cre recombinase. The precise activity of each of these transgenic alleles has not been studied, and previous reports suggest that their activity can depend on breeding strategies. We bred mice with a conditional allele of the essential telomere capping protein TRF2 with two different SFTPC-Cre-transgenic strains and observed opposite phenotypes (100% lethality vs. 100% viability). We characterized the Cre recombinase activity in these two transgenic lines and found that the contrasting phenotypes were driven by difference in embryonic expression of the two transgenes, likely due to position effects or differences in the transgenic constructs. We also tested if SFTPC-Cre activity was dependent on maternal or paternal inheritance. When paternally inherited, both SFTPC-Cre alleles produced offspring with constitutive reporter activity independent of the inheritance of the Cre allele, suggesting that Cre recombinase was expressed in the male germline before meiosis. Immunohistochemical analysis of the testis showed reporter activity during spermatogenesis. Analysis of single-cell RNA sequencing data from murine and human testis demonstrated SFTPC expression uniquely during human spermatogenesis, suggesting that use of the human promoter in these constructs is responsible for male germline activity. Our data highlight the importance of careful analysis of transgenic allele activity and identify an SFTPC-Cre allele that is useful for panepithelial targeting in the mouse. [ABSTRACT FROM AUTHOR]

Surfactant protein (SP)-C deficiency is found in samples from patients with idiopathic pulmonary fibrosis, especially in familial forms of this disease. We hypothesized that SP-C may contribute to fibrotic remodeling in aging mice and alveolar lipid homeostasis. For this purpose, we analyzed lung function, alveolar dynamics, lung structure, collagen content, and expression of genes related to lipid and cholesterol metabolism of aging SP-C knockout mice. In addition, in vitro experiments with an alveolar macrophage cell line exposed to lipid vesicles with or without cholesterol and/or SP-C were performed. Alveolar dynamics showed progressive alveolar derecruitment with age and impaired oxygen saturation. Lung structure revealed that decreasing volume density of alveolar spaces was accompanied by increasing of the ductal counterparts. Simultaneously, septal wall thickness steadily increased, and fibrotic wounds appeared in lungs from the age of 50 weeks. This remarkable phenotype is unique to the 129Sv strain, which has an increased absorption of cholesterol, linking the accumulation of cholesterol and the absence of SP-C to a fibrotic remodeling process. The findings of this study suggest that overall loss of SP-C results in an age-dependent, complex, heterogeneous phenotype characterized by a combination of overdistended air spaces and fibrotic wounds that resembles combined emphysema and pulmonary fibrosis in patients with idiopathic pulmonary fibrosis. Addition of SP-C to cholesterol-laden lipid vesicles enhanced the expression of cholesterol metabolism and transport genes in an alveolar macrophage cell line, identifying a potential new lipid–protein axis involved in lung remodeling. [ABSTRACT FROM AUTHOR]

Tenascin-C (TNC) is an extracellular matrix protein expressed at high levels during lung organogenesis. Later, TNC is only transiently de novo expressed to orchestrate tissue repair in pathological situations. We previously showed that TNC inactivation affects lung development and thus evaluated here the implications on lung function in newborn/adult mice. Respiratory function parameters were measured in anesthetized and mechanically ventilated wild-type (WT) and TNC-deficient mice at 5 (P5) and 90 (P90) days of age under basal conditions, as well as following high tidal volume (HTV) ventilation. At P5, TNC-deficient mice showed an increased static compliance (Cst) and inspiratory capacity (IC) relative to WT at baseline and throughout HTV. At P90, however, Cst and IC were only elevated at baseline. Control non-ventilated newborn and adult TNC-deficient mice showed similar lung morphology, but less alpha smooth muscle actin (α-SMA) around small airways. SMA + cells were decreased by 50% in adult TNC-deficient lungs and collagen layer thickened around small airways. Increased surfactant protein C (SP-C) and altered TGFβ and TLR4 signaling pathways were also detected. Thus, TNC inactivation-related defects during organogenesis led to persisting functional impairment in adulthood. This might be of interest in the context of pulmonary diseases with thickened airway smooth muscle layer or ventilation heterogeneity, like asthma and COPD. [ABSTRACT FROM AUTHOR]

Abstract Background The purpose of this study was to employ a novel ex vivo lung model of congenital diaphragmatic hernia (CDH) to determine how a mechanical compression affects early pulmonary development. Methods Day-15 whole fetal rat lungs (n = 6-12/group) from nitrofen-exposed and normal (vehicle only) dams were explanted and cultured ex vivo in compression microdevices (0.2 or 0.4 kPa) for 16 h to mimic physiologic compression forces that occur in CDH in vivo. Lungs were evaluated with significance set at P < 0.05. Results Nitrofen-exposed lungs were hypoplastic and expressed lower levels of surfactant protein C at baseline. Although compression alone did not alter the α-smooth muscle actin (ACTA2) expression in normal lungs, nitrofen-exposed lungs had significantly increased ACTA2 transcripts (0.2 kPa: 2.04 ± 0.15; 0.4 kPa: 2.22 ± 0.11; both P < 0.001). Nitrofen-exposed lungs also showed further reductions in surfactant protein C expression at 0.2 and 0.4 kPa (0.53 ± 0.04, P < 0.01; 0.69 ± 0.23, P < 0.001; respectively). Whereas normal lungs exposed to 0.2 and 0.4 kPa showed significant increases in periostin (POSTN), a mechanical stress–response molecule (1.79 ± 0.10 and 2.12 ± 0.39, respectively; both P < 0.001), nitrofen-exposed lungs had a significant decrease in POSTN expression (0.4 kPa: 0.67 ± 0.15, P < 0.001), which was confirmed by immunohistochemistry. Conclusions Collectively, these pilot data in a model of CDH lung hypoplasia suggest a primary aberration in response to mechanical stress within the nitrofen lung, characterized by an upregulation of ACTA2 and a downregulation in SPFTC and POSTN. This ex vivo compression system may serve as a novel research platform to better understand the mechanobiology and complex regulation of matricellular dynamics during CDH fetal lung development. [ABSTRACT FROM AUTHOR]

Hyperglycemia during pregnancy is associated with fetal lung development disorders and surfactant protein (SP) deficiency. Here, we examined the role of FOXA2 and Akt signaling in fetal lung development during diabetic pregnancy. Sprague‐Dawley rats were injected with streptozocin (STZ) during pregnancy to induce diabetes (DM). DM‐exposed fetal lungs exhibited reduced numbers of alveoli, irregularities in the appearance and thickness of the alveolar septum, increased levels of glycogen and lipids in type II alveolar epithelial cells, fewer microvilli and mature lamellar bodies, and swollen mitochondria. SP‐B and SP‐C in DM amniotic fluid and DM lungs were lower than in the control group (P < 0.05). DM lung nuclear FOXA2 was lower compared with the control group (P < 0.05), but p‐FOXA2 was higher (P < 0.05). In murine lung epithelial (MLE) 12 cells, p‐AKT levels were increased by high glucose/insulin, but decreased by the Akt inhibitor MK2206 (P < 0.05). Expression of nuclear FOXA2 was increased by MK2206 compared with the high glucose/insulin group (P < 0.05). These results suggest that maternal diabetes induces fetal lung FOXA2 phosphorylation through the Akt pathway, and also affects the maturation of alveolar epithelial cells and reduces levels of SP‐B and SP‐C in the fetal lungs. An Akt inhibitor reversed the changes in SP expression in vitro. [ABSTRACT FROM AUTHOR]

Inactivation of pulmonary surfactant by different components such as serum, cholesterol or meconium contributes to severe respiratory pathologies through destabilization and collapse of airspaces. Recent studies have analyzed in detail how the interfacial properties of natural surfactant purified from animal lungs are altered as a consequence of its exposure to serum proteins or meconium-mobilized cholesterol. It has been also demonstrated that pre-exposure of surfactant to polymers such as hyaluronic acid provides resistance to inactivation by multiple inhibitory agents. In the current work, we have extended these studies to the analysis of Surfacen, a clinical surfactant currently in use to rescue premature babies suffering or at risk of respiratory distress due to congenital lack of surfactant. This surfactant is also strongly inhibited by both meconium and serum when tested in the captive bubble surfactometer (CBS) under conditions mimicking respiratory dynamics. As it occurs with native surfactant, Surfacen is markedly protected from inhibition by pre-exposure to hyaluronic acid, confirming that clinical surfactants can be improved to treat pathologies associated with strongly deactivating contexts, such as those associated with lung injury and inflammation. Remarkably, we found that, under physiologically-mimicking conditions, a cholesterol-free clinical surfactant such as Surfacen is less susceptible to inhibition by cholesterol-mobilizing environments than cholesterol-containing natural surfactant, as a consequence of a markedly reduced susceptibility to incorporation of exogenous cholesterol. [ABSTRACT FROM AUTHOR]

Epithelial cell dysfunction is postulated as an important component in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Mutations in the surfactant protein C (SP-C) gene (SFTPC), an alveolar type II (AT2) cell-restricted protein, have been found in sporadic and familial IPF. To causally link these events, we developed a knockin mouse model capable of regulated expression of an IPF-associated isoleucine-to-threonine substitution at codon 73 (I73T) in Sftpc (SP-CI73T). Tamoxifen-treated SP-CI73T cohorts developed rapid increases in SftpcI73T mRNA and misprocessed proSP-CI73T protein accompanied by increased early mortality (days 7-14). This acute phase was marked by diffuse parenchymal lung injury, tissue infiltration by monocytes, polycellular alveolitis, and elevations in bronchoalveolar lavage and AT2 mRNA content of select inflammatory cytokines. Resolution of alveolitis (2-4 weeks), commensurate with a rise in TGF-β1, was followed by aberrant remodeling marked by collagen deposition, AT2 cell hyperplasia, α-smooth muscle actin-positive (α-SMA-positive) cells, and restrictive lung physiology. The translational relevance of the model was supported by detection of multiple IPF biomarkers previously reported in human cohorts. These data provide proof of principle that mutant SP-C expression in vivo causes spontaneous lung fibrosis, strengthening the role of AT2 cell dysfunction as a key upstream driver of IPF pathogenesis. [ABSTRACT FROM AUTHOR]

Phosgene-induced acute lung injury (P-ALI) is characterized by inflammation and effective treatments are lacking. Angiopoietin-1 (Ang1) has the beneficial effects on P-ALI. Mesenchymal stem cells (MSCs) have the potential for re-epithelization and recovery in lung injury. Thus, we hypothesized that Ang1 expressing MSCs would have beneficial effects on P-ALI. Here, an Ang1 expressing lentiviral vector was constructed and infected into rat bone marrow MSCs. Histological analyses revealed significant pathological improvements especially after treatment with MSCs in the rats exposed to phosgene. Ang1 facilitated the homing of MSCs to injured lung tissue and significantly increased expression of both epithelial cell marker Aquaporin-5 (AQP5) and surfactant protein-C (SPC) in the lung tissues. Moreover, MSCs-Ang1 reduced level of pro-inflammatory cytokines TGF-β1 and IL-1β and increased the expression of the anti-inflammatory cytokine IL-10 in the serum and bronchoalveolar lavage fluid (BALF) of P-ALI rats. In conclusion, our results suggest that Ang1 may improve the therapeutic potential of MSCs for P-ALI treatment. [ABSTRACT FROM AUTHOR]

Pulmonary emphysema is a respiratory condition characterized by alveolar destruction that leads to airflow limitation and reduced lung function. Although with extensive research, the pathophysiology of emphysema is poorly understood and effective treatments are still missing. Evidence suggests that mesenchymal stem cells (MSCs) possess the ability to engraft the injured tissues and induce repair via a paracrine effect. Thus, the aim of this study was to test the effects of the intratracheal administration of lung-derived mouse MSCs in a model of elastase-induced emphysema. Pulmonary function (static lung compliance) showed an increased stiffness induced by elastase, while morphometric findings (mean linear intercept and tissue/alveolar area) confirmed the severity of alveolar disruption. Contrarily, MSC administration partially restored lung elasticity and alveolar architecture. In the absence of evidence that MSCs acquired epithelial phenotype, we detected an increased proliferative activity of aquaporin 5- and surfactant protein C-positive lung cells, suggesting MSC-driven paracrine mechanisms. The data indicate the mediation of hepatocyte growth factor in amplifying MSC-driven tissue response after injury. Our study shed light on supportive properties of lung-derived MSCs, although the full identification of mechanisms orchestrated by MSCs and responsible for epithelial repair after injury is a critical aspect yet to be achieved. [ABSTRACT FROM AUTHOR]

Familial interstitial lung disease (ILD) is defined as presence of ILD in 2 or more family members. Surfactant protein C (SFTPC) gene mutations are rare, but well-known cause of familial ILD. We reported a 20-year-old male, who was referred for lung transplantation. He was symptomatic at age 3 and underwent surgical lung biopsy at age 6, which revealed a nonspecific interstitial pneumonia (NSIP) pattern. Genetic workup revealed a novel SFTPC mutation in the first intron with a C to A transversion. At age 21, he underwent bilateral lung transplantation. Explanted lung histology suggested NSIP. In addition there was pulmonary neuroendocrine cell (PNEC) hyperplasia and carcinoid tumorlets. His mother had undergone lung transplantation several years earlier, and her explanted lung showed similar pathology. SFTPC mutations are inherited in an autosomal dominant pattern. Various types of ILD have been associated with SFTPC mutation including NSIP, usual interstitial pneumonia (UIP), and desquamative interstitial pneumonia (DIP). PNEC hyperplasia has been described to occur in association with lung inflammation but has not been previously described with familial ILD associated with SFTPC mutation. [ABSTRACT FROM AUTHOR]

Background: Respiratory distress syndrome (RDS) is a severe pulmonary disease that mainly affects preterm neonates. Surfactant-protein genes' polymorphisms have been mostly evaluated as the candidate contributors in genetics of RDS. However, the results are diverse in different populations. We aimed at investigating the association of rs1124 with RDS development.Method: Three hundred and thirty five preterm neonates were enrolled in a multicenter case-control study. Respiratory distress (RD) was scored according to Downes' scoring system. Genotyping was performed by PCR-RFLP method.Result: One hundred and sixty six neonates showed RDS and 169 did not. Gestational age (GA) was significantly lower in RDS group compared to the controls. In female preterm newborns, AA genotype was found more frequently in RDS group. In RDS group, AA genotype was also associated with milder RD irrespective of gender. In neonates who were born 28-34 weeks, RD appeared to be more severe in the RDS group and males.Conclusions: This is the first report of association of SFTPC rs1124 polymorphism with RDS development in Iranian newborns. The current study suggests that GA <28-weeks is the most important factor in predisposition to RDS. AA genotype is also, a predisposing factor for the development of RDS in female preterm infants. [ABSTRACT FROM AUTHOR]

BACKGROUND: The goal of this study was to determine if exposure to meconium would alter the phenotype of amniotic fluid mesenchymal stem cells (AF-MSCs) and the ability of these cells to be differentiated into distal airway type cells. METHODS: Meconium was collected, lyophilized and resuspended in PBS at 3 different concentrations (high, medium, and low). AF-MSCs were cultured in the presence of this meconium suspension for 8 hours and then analyzed for changes in gene expression. Additionally, AF-MSCs exposed to meconium were differentiated for 14 days using modified small airway growth medium (mSAGM) and gene expression was determined. As a spontaneous differentiation control, meconium exposed AF-MSCs were cultured in amniotic fluid stem cell medium (AF medium). RESULTS: After 8 hours of exposure in culture, AF-MSCs had increased expression of distal airway genes aquaporin 5 (AQP5) and surfactant protein c (SPC) when cultured in AF medium containing meconium. These gene expression levels were similar to that of AF-MSCs that were differentiated in mSAGM for 14 days. Furthermore, there was an up regulation of pluripotency genes NANOG and OCT4 in response to low meconium concentration for 8 hours. Following 14 days of culture in mSAGM, there was an upregulation of TTF1, SPC and AQP5 expression in the control, as well as in the low and medium meconium exposed groups indicating that these cells were still able to be differentiated. High meconium concentration did, however, appear to influence the level of distal airway gene expression after 14 days in mSAGM. After 14 days in AF medium, there was significant downregulation in pluripotency and mesenchymal markers as well as distal airway gene expression in all groups. CONCLUSION: The phenotype of AF-MSCs is modulated by meconium exposure; however, the cells were still able to differentiate into distal airway gene and protein expression. This result supports the hypothesis that progenitor cells exist in the amniotic fluid and the presence of meconium may affect their initial phenotype. However, these cells were still able to be differentiated to a distal lung phenotype. [ABSTRACT FROM AUTHOR]

Pulmonary surfactant protein C (SP-C) expression by type II alveolar epithelial cells (AECs) is markedly reduced in diverse types of lung injuries and is often associated with AEC apoptosis. It is unclear whether loss of SP-C contributes to the increased p53 and urokinase-type plasminogen activator (uPA) system cross-talk and apoptosis of AECs. Therefore, we inhibited SP-C expression in human and murine AECs using lentivirus vector expressing shRNA and tested p53 and downstream changes in the uPA-fibrinolytic system. Inhibition of SP-C expression in AECs induced p53 and activated caspase-3, indicating AEC apoptosis. We also found that bleomycin or cigarette smoke exposure failed to inhibit SP-C expression or apoptosis in AECs in p53- and plasminogen activator inhibitor-1 (PAI-1)-deficient mice. Depletion of SP-C expression by lentiviral SP-C shRNA in PAI-1-deficient mice failed to induce p53 or apoptosis in AECs, whereas it increased both AEC p53 and apoptosis in wild-type and uPA-deficient mice. SP-C inhibition in AECs also increased in CXCL1 and CXCL2 and their receptor CXCR2 as well as ICAM-1 expression, which is indicative of a proinflammatory response. Overexpression of p53-binding 3=-UTR sequences in AECs inhibited PAI-1 induction while maintaining uPA and uPAR protein and mRNA expression. Furthermore, caveolin-1 expression and phosphorylation were increased in AECs, indicating an intricate link between caveolin-1 and Src kinase-mediated cell signaling and AEC apoptosis due to loss of SP-C expression through p53 and uPA system-mediated cross-talk. The role of uPA, PAI-1, and p53 in the regulation of AEC apoptosis after injury was also determined in knockout mice. [ABSTRACT FROM AUTHOR]

Background Surfactant proteins (SP’s) have been described as inherent proteins of the human central nervous system (CNS). Their distribution pattern in brain tissue and altered cerebrospinal fluid (CSF) – concentrations in different CNS pathologies are indicative of their immunological and rheological importance. The aim of this study has been to investigate when – compared to the lungs – SP’s are expressed in the developing rat brain and which functional components in the CNS participate in their production. Material and methods Brain and lung tissue from embryonal (days 10, 12, 14, 16, 17 and 20), newborn, and adult rats were harvested and investigated for expression of SP-A, SP-B, SP-C and SP-D using immunofluorescence microscopy in order to identify and compare the time points of their occurence in the respective tissue. To better identify the location of SP expression in the rat brain, SP’s were colocalized with use of an astrocyte marker (GFAP), a neuronal marker (NeuN), an endothelial marker (CD31) and an axonal marker (NF). Results and conclusion SP-A and SP-C are expressed in the CNS of rats during early embryonic age whereas SP-B and SP-D are first present in the adult rat brain. All SP’s are expressed in cells adjacent to CSF spaces, probably influencing and maintaining physiological CSF flow. SP’s A and C are abundant at the site of the blood brain barrier (BBB). [ABSTRACT FROM AUTHOR]

Lipopolysaccharide (LPS), a Gram-negative bacterial outer membrane component, is one of the major causes of septic shock. Herein we investigate LPS-induced apoptosis of rat alveolar epithelial type II cells (AEC II) and the effects of LPS on surfactant protein-C (SP-C) expression in AEC II, along with the possible molecular mechanisms. LPS exposure impaired cell viability and increased apoptosis of AEC II significantly in concentration-dependent manner embodied in increased caspase-3 expression and the activity of caspase-3. Simultaneously, our results also indicated that LPS inhibited surfactant protein-C (SP-C) expression in AEC II. Mechanistic studies revealed that LPS treatment significantly increased the expression of NF-κB p50, NF-κB p65 and IKKß proteins as well as induced IκB-a phosphorylation. Moreover, pretreatment with IKK inhibitor IKK-16 or NF-κB inhibitor PDTC ameliorated LPScaused alterations in cleaved caspase-3 expression, the activity of caspase-3 and SP-C expression. Taken together, these results demonstrate that LPS can induce apoptosis of AEC II and decrease SP-C expression partly through activating the NF-κB pathway. [ABSTRACT FROM AUTHOR]

Background There is a strong link between smaller air pollution particles and a range of serious health conditions. Thus, there is a need for understanding the impacts of airborne fine particulate matter (PM) with an aerodynamic diameter of < 1 μm (PM 1 ) on lung alveolar epithelial cells. In the present study, mouse lung epithelial type II cell MLE-12 cells were used to examine the intracellular oxidative responses and the surfactant protein expressions after exposure to various concentrations of PM 1 collected from an urban site and a steel-factory site (referred as uPM 1 and sPM 1 hereafter, respectively). Methods Physicochemical characterization of PM 1 was performed by using scanning electron microscopy and transmission electron microscopy. Cytotoxicity and autophagy induced by PM 1 were assessed by using comprehensive approaches after MLE-12 cells were exposed to different concentrations of PM 1 for various times. Expression of surfactant proteins B and C in MLE-12 cells was determined by Western blotting. Results All of the tested PM 1 induced cytotoxicity evidenced by significant decrease of cell viability and increase of lactate dehydrogenase (LDH) release in a time- and concentration-dependent manner in the exposed cells compared with the unexposed cells. A similar pattern of increase of intercellular reactive oxygen species (ROS) generation and decrease of superoxide dismutase (SOD) and catalase (CAT) activities was also observed. PM 1 -induced autophagy was evidenced by an increase in microtubule-associated protein light chain-3 (LC3) puncta, accumulation of LC3II, and increased levels of beclin1. Data from Western blotting showed significant decrease of surfactant protein B and C expressions. Relatively high concentrations of transition metals, including Fe, Cu and Mn, may be responsible for the higher toxicity of sPM 1 compared with uPM 1 . Moreover, pretreatment with N -acetylcysteine (NAC) or Chelex (a metal chelating agent, which removes a large suite of metals from PM 1 ) prevented the increase of PM 1 -inudced ROS generation and autophagy, and down-regulated the expression of surfactant proteins B and C. Conclusion PM 1 , particularly PM 1 with high concentrations of transition metals, such as Fe, Cu and Mn, induces oxidative damage and autophagy, as well as inhibits surfactant protein B and C expressions in lung alveolar type II epithelial cells. General significance This study will help to understand the mechanism underlying the toxicological effects of PM 1 in lung alveolar type II epithelial cells. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu. [ABSTRACT FROM AUTHOR]

Pulmonary surfactant is a complex fluid that comprises phospholipids and four proteins (SP-A, SP-B, SP-C, and SP-D) with different biological functions. SP-B, SP-C, and SP-D are essential for the lungs' surface tension function and for the organization, stability and metabolism of lung parenchyma. SP-A and SP-D, which are also known as pulmonary collectins, have an important function in the host's lung immune response; they act as opsonins for different pathogens via a C-terminal carbohydrate recognition domain and enhance the attachment to phagocytic cells or show their own microbicidal activity by increasing the cellular membrane permeability. Interactions between the pulmonary collectins and bacteria or viruses have been extensively studied, but this is not the same for fungal pathogens. SP-A and SP-D bind glucan and mannose residues from fungal cell wall, but there is still a lack of information on their binding to other fungal carbohydrate residues. In addition, both their relation with immune cells for the clearance of these pathogens and the role of surfactant proteins' regulation during respiratory fungal infections remain unknown. Here we highlight the relevant findings associated with SP-A and SP-D in those respiratory mycoses where the fungal infective propagules reach the lungs by the airways. [ABSTRACT FROM AUTHOR]