Surfactant protein D in human lung diseases

Expression and basic biochemical characteristics of recombinant surfactant protein D of bottlenose dolphin (Tursiopstruncatus)

We previously identified surfactant protein D (SP-D) in the bottlenose dolphin Tursiops truncatus as a unique evolutionary factor of the cetacean pulmonary immune system. In this short report, recombinant SP-D of bottlenose dolphin (dSP-D) was synthesized in mammalian cells, and its properties were analyzed in vitro. The recombinant proteins were purified using Ni-carrier or Co-carrier. Sodium dodecyl sulfate poly-acrylamide gel electrophoresis and western blotting revealed a 50 kDa major band with minor secondary bands. Enzyme-linked immunosorbent assay-like methods revealed that recombinant dSP-D bonded to gram-positive and gram-negative bacterial walls. Our findings suggest the clinical usefulness of dSP-D for cetacean pneumonia.

ADAM-17 Activity and Its Relation to ACE2: Implications for Severe COVID-19

There is a lack of studies aiming to assess cellular a disintegrin and metalloproteinase-17 (ADAM-17) activity in COVID-19 patients and the eventual associations with the shedding of membrane-bound angiotensin-converting enzyme 2 (mACE2). In addition, studies that investigate the relationship between ACE2 and ADAM-17 gene expressions in organs infected by SARS-CoV-2 are lacking. We used data from the Massachusetts general hospital COVID-19 study (306 COVID-19 patients and 78 symptomatic controls) to investigate the association between plasma levels of 33 different ADAM-17 substrates and COVID-19 severity and mortality. As a surrogate of cellular ADAM-17 activity, an ADAM-17 substrate score was calculated. The associations between soluble ACE2 (sACE2) and the ADAM-17 substrate score, renin, key inflammatory markers, and lung injury markers were investigated. Furthermore, we used data from the Genotype-Tissue Expression (GTEx) database to evaluate ADAM-17 and ACE2 gene expressions by age and sex in ages between 20-80 years. We found that increased ADAM-17 activity, as estimated by the ADAM-17 substrates score, was associated with COVID-19 severity (p = 0.001). ADAM-17 activity was also associated with increased mortality but did not reach statistical significance (p = 0.06). Soluble ACE2 showed the strongest positive correlation with the ADAM-17 substrate score, follow by renin, interleukin-6, and lung injury biomarkers. The ratio of ADAM-17 to ACE2 gene expression was highest in the lung. This study indicates that increased ADAM-17 activity is associated with severe COVID-19. Our findings also indicate that there may a bidirectional relationship between membrane-bound ACE2 shedding via increased ADAM-17 activity, dysregulated renin-angiotensin system (RAS) and immune signaling. Additionally, differences in ACE2 and ADAM-17 gene expressions between different tissues may be of importance in explaining why the lung is the organ most severely affected by COVID-19, but this requires further evaluation in prospective studies.

Could SP-A and SP-D Serum Levels Predict COVID-19 Severity?

Given the various clinical manifestations that characterize Coronavirus Disease 2019 (COVID-19), the scientific community is constantly searching for biomarkers with prognostic value. Surfactant proteins A (SP-A) and D (SP-D) are collectins that play a crucial role in ensuring proper alveolar function and an alteration of their serum levels was reported in several pulmonary diseases characterized by Acute Respiratory Distress Syndrome (ARDS) and pulmonary fibrosis. Considering that such clinical manifestations can also occur during Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, we wondered if these collectins could act as prognostic markers. In this regard, serum levels of SP-A and SP-D were measured by enzyme immunoassay in patients with SARS-CoV-2 infection (n = 51) at admission (T0) and after seven days (T1) and compared with healthy donors (n = 11). SP-D increased in COVID-19 patients compared to healthy controls during the early phases of infection, while a significant reduction was observed at T1. Stratifying SARS-CoV-2 patients according to disease severity, increased serum SP-D levels were observed in severe compared to mild patients. In light of these results, SP-D, but not SP-A, seems to be an eligible marker of COVID-19 pneumonia, and the early detection of SP-D serum levels could be crucial for preventive clinical management.

Trauma diagnostic-related target proteins and their detection techniques

Trauma is a significant health issue that not only leads to immediate death in many cases but also causes severe complications, such as sepsis, thrombosis, haemorrhage, acute respiratory distress syndrome and traumatic brain injury, among trauma patients. Target protein identification technology is a vital technique in the field of biomedical research, enabling the study of biomolecular interactions, drug discovery and disease treatment. It plays a crucial role in identifying key protein targets associated with specific diseases or biological processes, facilitating further research, drug design and the development of treatment strategies. The application of target protein technology in biomarker detection enables the timely identification of newly emerging infections and complications in trauma patients, facilitating expeditious medical interventions and leading to reduced post-trauma mortality rates and improved patient prognoses. This review provides an overview of the current applications of target protein identification technology in trauma-related complications and provides a brief overview of the current target protein identification technology, with the aim of reducing post-trauma mortality, improving diagnostic efficiency and prognostic outcomes for patients.

Lung surfactant as a biophysical assay for inhalation toxicology

Lung surfactant (LS) is a mixture of lipids and proteins that forms a thin film at the gas-exchange surfaces of the alveoli. The components and ultrastructure of LS contribute to its biophysical and biochemical functions in the respiratory system, most notably the lowering of surface tension to facilitate breathing mechanics. LS inhibition can be caused by metabolic deficiencies or the intrusion of endogenous or exogenous substances. While LS has been sourced from animals or synthesized for clinical therapeutics, the biofluid mixture has also gained recent interest as a biophysical model for inhalation toxicity. Various methods can be used to evaluate LS function quantitatively or qualitatively after exposure to potential toxicants. A narrative review of the recent literature was conducted. Studies focused whether LS was inhibited by various environmental contaminants, nanoparticles, or manufactured products. A review is also conducted on synthetic lung surfactants (SLS), which have emerged as a promising alternative to conventional animal-sourced LS. The intrinsic advantages and recent advances of SLS make a strong case for more widespread usage in LS-based toxicological assays.

Surfactant protein D (SP-D) as a biomarker of SARS-CoV-2 infection

Background

Surfactant protein-D (SP-D) is a lung-resident protein that has emerged as a potential biomarker for COVID-19. Previous investigations on acute respiratory distress syndrome patients demonstrated a significant increment of SP-D serum levels in pathological conditions. Since SP-D is not physiologically permeable to alveoli-capillary membrane and poorly expressed by other tissues, this enhancement is likely due to an impairment of the pulmonary barrier caused by prolonged inflammation.

Methods

A retrospective study on a relatively large cohort of patients of Hospital Pio XI of Desio was conducted to assess differences of the hematic SP-D concentrations among COVID-19 patients and healthy donors and if SP-D levels resulted a risk factor for disease severity and mortality.

Results

The first analysis, using an ANOVA-model, showed a significant difference in the mean of log SP-D levels between COVID-19 patients and healthy donors. Significant variations were also found between dead vs survived patients. Results confirm that SP-D concentrations were significantly higher for both hospitalized COVID-19 and dead patients, with threshold values of 150 and 250 ng/mL, respectively. Further analysis conducted with Logistic Mixed models, highlighted that higher SP-D levels at admission and increasing differences among follow-up and admission values resulted the strongest significant risk factors of mortality (model predictive accuracy, AUC = 0.844).

Conclusions

The results indicate that SP-D can be a predictive marker of COVID-19 disease and its outcome. Considering its prognostic value in terms of mortality, the early detection of SP-D levels and its follow-up in hospitalized patients should be considered to direct the therapeutic intervention.

Surfactant protein D: A useful biomarker for distinguishing COVID‐19 pneumonia from COVID‐19 pneumonia‐like diseases

Introduction

Computed tomography is useful for the diagnosis of coronavirus disease (COVID‐19) pneumonia. However, many types of interstitial lung diseases and even bacterial pneumonia can show abnormal chest shadows that are indistinguishable from those observed in COVID‐19 pneumonia. Thus, it is necessary to identify useful biomarkers that can efficiently distinguish COVID‐19 pneumonia from COVID‐19 pneumonia‐like diseases. Herein, we investigated the usefulness of serum Krebs von den Lungen 6 (KL‐6) and surfactant protein D (SP‐D) for identifying patients with COVID‐19 pneumonia among patients with abnormal chest shadows consistent with COVID‐19 pneumonia.

Method

This was a retrospective cohort study of consecutive patients who underwent evaluation of serum KL‐6 and SP‐D at a single center from February 2019 to December 2020. A total of 54 patients with COVID‐19 pneumonia and 65 patients with COVID‐19 pneumonia‐like diseases were enrolled in this study from the source population. Serum KL‐6 and SP‐D levels in both groups were analyzed.

Result

The serum levels of KL‐6 and SP‐D in patients with COVID‐19 pneumonia were significantly lower than those in patients with COVID‐19 pneumonia‐like disease (median [interquartile range]: 208.5 [157.5–368.5] U/ml vs. 430 [284.5–768.5] U/ml, p < 0.0001 and 24.7 [8.6–51.0] ng/ml vs. 141 [63.7–243.5] ng/ml, p < 0.0001, respectively). According to receiver operating characteristic (ROC) analysis, the areas under the ROC curves (95% confidence intervals) of serum KL‐6 and SP‐D levels for distinguishing COVID‐19 pneumonia from COVID‐19 pneumonia‐like diseases were 0.761 (0.675–0.847) and 0.874 (0.812–0.936), respectively. The area under the ROC curve of serum SP‐D was significantly larger than that of serum KL‐6 (p = 0.0213), suggesting that serum SP‐D can more efficiently distinguish COVID‐19 pneumonia from COVID‐19 pneumonia‐like diseases.

Conclusion

Serum SP‐D is a promising biomarker for distinguishing COVID‐19 pneumonia from COVID‐19 pneumonia‐like diseases. Serum SP‐D can be useful for the management of patients with abnormal chest shadow mimicking COVID‐19 pneumonia.

Ammonia exposure by intratracheal instillation causes severe and deteriorating lung injury and vascular effects in mice

OBJECTIVE

Ammonia (NH₃) is a corrosive alkaline gas that can cause life-threatening injuries by inhalation. The aim was to establish a disease model for NH₃-induced injuries similar to acute lung injury (ALI) described in exposed humans and investigate the progression of lung damage, respiratory dysfunction and evaluate biomarkers for ALI and inflammation over time.

METHODS

Female BALB/c mice were exposed to an NH₃ dose of 91.0 mg/kg·bw using intratracheal instillation and the pathological changes were followed for up to 7 days.

RESULTS

NH₃ instillation resulted in the loss of body weight along with a significant increase in pro-inflammatory mediators in both bronchoalveolar lavage fluid (e.g. IL-1β, IL-6, KC, MMP-9, SP-D) and blood (e.g. IL-6, Fibrinogen, PAI-1, PF4/CXCL4, SP-D), neutrophilic lung inflammation, alveolar damage, increased peripheral airway resistance and methacholine-induced airway hyperresponsiveness compared to controls at 20 h. On day 7 after exposure, deteriorating pathological changes such as increased macrophage lung infiltration, heart weights, lung hemorrhages and coagulation abnormalities (elevated plasma levels of PAI-1, fibrinogen, endothelin and thrombomodulin) were observed but no increase in lung collagen. Some of the analyzed blood biomarkers (e.g. RAGE, IL-1β) were unaffected despite severe ALI and may not be significant for NH₃-induced damages.

CONCLUSIONS

NH₃ induces severe acute lung injuries that deteriorate over time and biomarkers in lungs and blood that are similar to those found in humans. Therefore, this model has potential use for developing diagnostic tools for NH₃-induced ALI and for finding new therapeutic treatments, since no specific antidote has been identified yet.

Blood Levels of Indicators of Lower Respiratory Tract Damage in Chronic Bronchitis in Patients with Abdominal Obesity

Objective: to study biomolecules associated with pathology in the respiratory system, in particular, with the development of chronic bronchitis in patients with abdominal obesity. Materials and methods: This is a pilot study. The main group consisted of 158 people with chronic bronchitis, divided into two subgroups: one with abdominal obesity, and the other without it. The control group consisted of 68 people without chronic bronchitis. We determined the blood levels of SP-A, SP-D, α1-antitrypsin, CC16, PARC, and RELM-β. Results: In the first subgroup, patients significantly more often complained of coughing, experienced shortness of breath 1.5 times more often with light physical exertion and 2.7 times more often with moderate physical exertion. In these patients, a Tiffeneau–Pinelli index (FEV1/FVC) below 70% was 1.8 times more common, more patients had FEV1 and FVC of less than 80%, and presented a statistically significant decrease in SP-A, α1-antitrypsin, CC16 levels and an increase in PARC levels than in the second subgroup. Conclusion: In patients with chronic bronchitis and abdominal obesity, there is a decrease in the levels of SP-A, α1-antitrypsin, CC16 and an increase in the level of PARC compared with patients without abdominal obesity, which is probably due to the presence of an additional source of chronic inflammation associated with adipose tissue.

Firefighters' occupational exposure: Contribution from biomarkers of effect to assess health risks

Firefighting is physically and physiologically exhausting besides encompassing exposure to toxic fire emissions. Biomonitoring studies from the past five years have been significantly contributing to characterize the occupational-related health effects in this group of professionals and to improve risk assessment. Therefore, this study gathers and critically discusses the most characterized biomarkers of effect (oxidative stress, DNA and protein damage, stress hormones, inflammation, and vascular, lung, and liver injury), including those potentially more promising to be explored in future studies, and their relation with health outcomes. Various studies proved an association between exposures to fire emissions and/or heat and significantly altered values of biomarkers of inflammation (soluble adhesion molecules, tumor necrosis factor, interleukins, and leucocyte count), vascular damage and tissue injury (pentraxin-3, vascular endothelial growth factor, and cardiac troponin T) in firefighting forces. Moreover, preliminary data of DNA damage in blood, urinary mutagenicity and 8-isoprostaglandin in exhaled breath condensate suggest that these biomarkers of oxidative stress should be further explored. However, most of the reported studies are based on cross-sectional designs, which limit full identification and characterization of the risk factors and their association with development of work-related diseases. Broader studies based on longitudinal designs and strongly supported by the analysis of several types of biomarkers in different biological fluids are further required to gain deeper insights into the firefighters occupational related health hazards and contribute to implementation of new or improved surveillance programs.

The novel effectiveness of Tai Chi on cardiopulmonary fitness among stroke patients in the recovery phase: a study protocol for a randomized controlled trial

BACKGROUND

Stroke is the leading cause of death worldwide. China faces a similar risk of stroke as developed countries because of considerable changes in lifestyle, such as overeating and smoking. Tai Chi is a traditional form of mind-body exercise that has been widely practiced in China for thousands of years. However, there are few studies on the effect of Tai Chi on the cardiopulmonary function of stroke patients in the recovery phase. Therefore, it is necessary to observe the effect of Tai Chi on the cardiorespiratory fitness of patients after stroke.

METHODS

This is a parallel-design, two-arm, analyst assessor-blinded, randomized controlled trial. A total of 226 stroke patients in the recovery phase will be recruited and assigned randomly to a control group or Tai Chi group at a 1:1 ratio. The patients in the Tai Chi group will perform the Tai Chi exercise. The patients in the control group will perform walking exercises. Patients in both groups will receive conventional treatments and healthy education. The primary outcomes will be VO_2peak and scores on the MOS item short form health survey (SF-36) scale. Secondary outcomes will include vital capacity (VC), ejection fractions (EF), and cardiac output (CO). The assessments of the tests will be performed at three time points (before exercise, at the end of exercise, and 6 weeks after exercise). Adverse events will be recorded faithfully during the study.

DISCUSSION

If the results are positive, this study will contribute to the establishment of further guided Tai Chi rehabilitation programs.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2000034719 . Registered on 16 July 2020.

Epidemiological and Clinical Characterization of Superinfections in Critically Ill Coronavirus Disease 2019 Patients

To describe the epidemiology of superinfections (occurring > 48 hr after hospital admission) and their impact on the ICU and 28-day mortality in patients with coronavirus disease 2019 with acute respiratory distress syndrome, requiring mechanical ventilation.

DESIGN

Retrospective analysis of prospectively collected observational data.

SETTING

University-affiliated adult ICU.

PATIENTS

Ninety-two coronavirus disease 2019 patients admitted to the ICU from February 21, 2020, to May 6, 2020.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The prevalence of superinfection at ICU admission was 21.7%, and 53 patients (57.6%) had at least one superinfection during ICU stay, with a total of 75 (82%) ventilator-associated pneumonia and 57 (62%) systemic infections. The most common pathogens responsible for ventilator-associated pneumonia were Pseudomonas aeruginosa (n = 26, 34.7%) and Stenotrophomonas maltophilia (n = 14, 18.7%). Bloodstream infection occurred in 16 cases, including methicillin-resistant Staphylococcus epidermidis (n = 8, 14.0%), Enterococcus species (n = 6, 10.5%), and Streptococcus species (n = 2, 3.5%). Fungal infections occurred in 41 cases, including 36 probable (30 by Candida albicans, six by C. nonalbicans) and five proven invasive candidiasis (three C. albicans, two C. nonalbicans). Presence of bacterial infections (odds ratio, 10.53; 95% CI, 2.31-63.42; p = 0.005), age (odds ratio, 1.17; 95% CI, 1.07-1.31; p = 0.001), and the highest Sequential Organ Failure Assessment score (odds ratio, 1.27; 95% CI, 1.06-1.63; p = 0.032) were independently associated with ICU or 28-day mortality.

CONCLUSIONS

Prevalence of superinfections in coronavirus disease 2019 patients requiring mechanical ventilation was high in this series, and bacterial superinfections were independently associated with ICU or 28-day mortality (whichever comes first).

Structural hallmarks of lung surfactant: Lipid-protein interactions, membrane structure and future challenges

Lung surfactant (LS) is an outstanding example of how a highly regulated and dynamic membrane-based system has evolved to sustain a wealth of structural reorganizations in order to accomplish its biophysical function, as it coats and stabilizes the respiratory air-liquid interface in the mammalian lung. The present review dissects the complexity of the structure-function relationships in LS through an updated description of the lipid-protein interactions and the membrane structures that sustain its synthesis, secretion, interfacial performance and recycling. We also revise the current models and the biophysical techniques employed to study the membranous architecture of LS. It is important to consider that the structure and functional properties of LS are often studied in bulk or under static conditions, in spite that surfactant function is strongly connected with a highly dynamic behaviour, sustained by very polymorphic structures and lipid-lipid, lipid-protein and protein-protein interactions that reorganize in precise spatio-temporal coordinates. We have tried to underline the evidences available of the existence of such structural dynamism in LS. A last important aspect is that the synthesis and assembly of LS is a strongly regulated intracellular process to ensure the establishment of the proper interactions driving LS surface activity, while protecting the integrity of other cell membranes. The use of simplified lipid models or partial natural materials purified from animal tissues could be too simplistic to understand the true molecular mechanisms defining surfactant function in vivo. In this line, we will bring into the attention of the reader the methodological challenges and the questions still open to understand the structure-function relationships of LS at its full biological relevance.

Genetic Association With Pseudomonas aeruginosa Acquisition in Cystic Fibrosis: Influence of Surfactant Protein D and Mannose-Binding Lectin

Background: Pseudomonas aeruginosa (PA) infection in cystic fibrosis (CF) is associated with poor prognosis. Surfactant protein-D (SFTPD) and mannose-binding lectin (MBL) play a critical role in innate immunity and response to bacterial infections. We investigated serum levels and genetic variants of SFTPD and MBL in CF patients. Method: Thirty-five Caucasian patients homozygous for ΔF508del were genotyped for functional relevant polymorphisms within MBL2 (promoter-221 Y/X, codons 52, 54, and 57) and SFTPD genes (Met11Thr, Ala160Thr, and Ser270Thr). Serum levels of collectins, clinical characteristics, and PA status were correlated with genetic data. Results: Patients age, gender, and PA status did not affect MBL and SFTPD serum concentrations. MBL concentrations were correlated with MBL haplotypes. Patients with chronic Pseudomonas aeroginosa infection (PAC) and MBL insufficiency had a shorter interval between first PA infection and onset of PAC (0.01 vs. 4.6 years, p < 0.04) as well as a lower median age at transition to PAC (9.8 vs. 16.4 years, p < 0.03) compared to MBL sufficient patients with PAC. SFTPD serum level and FEV1% (Spearman r = -0.41, p < 0.03) showed a negative correlation irrespective of PA infection status. The hazard ratio to PA acquisition was increased in carriers of the SFTPD haplotype 11Thr-160Ala-270Ser compared to carriers of the common 11Met-160Thr-270Ser haplotype [HR 3.0 (95%CI: 1.1-8.6), p < 0.04]. Conclusion: MBL insufficiency leads to a shorter interval between first PA infection and onset of chronic infection. Susceptibility to PA acquisition is associated with SFTPD genetic variants with 11Thr-160Ala-270Ser as risk haplotype for early PA infection. This may be due to presence of threonine associated with oligomeric structure of SFTPD and binding ability to bacteria.

Pulmonary Surfactants: a New Therapeutic Target in Asthma

Purpose of Review

Lung tissues are highly susceptible to airway inflammation as they are inevitably exposed to inhaled pathogens and allergens. In the lungs, clearance of infectious agents and regulation of inflammatory responses are important for the first-line defense, where surfactants play a role in host defense mechanisms. In this review, clinical significance of pulmonary surfactants in asthma has been highlighted.

Recent Findings

Surfactants, such as surfactant protein A (SP-A) and SP-D released from alveolar epithelium, reduce pathogen infection and control immune-cell activation. Especially, SP-D directly binds to eosinophil surface, leading to inhibition of extracellular trap formation and reduction in airway inflammation. Production of surfactants is commonly determined by both genetic (single nucleotide polymorphisms) and environmental factors influencing processes involved in the development of asthma. In addition, nintedanib (an intracellular inhibitor of tyrosine kinases) could increase SP-D levels and is used in patients with idiopathic pulmonary fibrosis. These findings may provide a possible application of SP-D in asthma.

Summary

Surfactants are key players contributing to host defense through maintaining the immune system. As clinical implications of surfactants involved in asthma have been suggested, further translational studies are needed to apply surfactants as an effective therapeutic target in patients with asthma.

Acute Lung Injury in Critically Ill Patients: Actin-Scavenger Gelsolin Signals Prolonged Respiratory Failure

Background:

Gelsolin is an actin-scavenger controlling the tissue damage from actin in the blood. Gelsolin levels in circulation drops when tissue damage and corresponding actin release is pronounced due to catabolic conditions. The purpose of this study was to determine if low plasma gelsolin independently predicts a reduced chance of weaning from ventilator-demanding respiratory failure in critically ill patients within 28 days from admission.

Results:

This cohort study included 746 critically ill patients with ventilator-demanding respiratory failure from the randomized clinical trial, “Procalcitonin And Survival Study (PASS).” Primary end point was successful weaning from mechanical ventilation within 28 days. We used multivariable Cox regression adjusted for age, sepsis, PaO₂/FiO₂ ratio and other known and suspected predictors of persistent respiratory failure. Follow-up was complete.

For medical patients, baseline-gelsolin below the 25th percentile independently predicted a 40% lower chance of successful weaning within 28 days (HR 0.60, 95% CI 0.46–0.79, P = 0.0002); among surgical patients this end point was not predicted. Low gelsolin levels predicted chance of being “alive and out of intensive care at day 14” for both medical and surgical patients (HR 0.69, 95% CI 0.54–0.89, P = 0.004). Gelsolin levels did not predict 28 day mortality for surgical or medical patients.

Conclusions:

Low levels of serum gelsolin independently predict a decreased chance of successful weaning from ventilator within 28 days among medical intensive care patients. This finding has implications for identifying patients who need individualized intervention early in intensive care course to prevent unfavorable lung prognosis in acute respiratory failure.

Trial registration:

This is a substudy to the PASS, Clinicaltrials.gov ID: NCT00271752, first registered January 1, 2006.

Neonatal endotoxin stimulation is associated with a long-term bronchiolar epithelial expression of innate immune and anti-allergic markers that attenuates the allergic response

Allergic asthma is the most common phenotype of the pathology, having an early-onset in childhood and producing a Th2-driven airways remodeling process that leads to symptoms and pathophysiological changes. The avoidance of aeroallergen exposure in early life has been shown to prevent asthma, but without repeated success and with the underlying preventive mechanisms at the beginning of asthma far to be fully recognized. In the present study, we aimed to evaluate if neonatal LPS-induced boost in epithelial host defenses contribute to prevent OVA-induced asthma in adult mice. To this, we focused on the response of bronchiolar club cells (CC), which are highly specialized in maintaining the epithelial homeostasis in the lung. In these cells, neonatal LPS administration increased the expression of TLR4 and TNFα, as well as the immunodulatory/antiallergic proteins: club cell secretory protein (CCSP) and surfactant protein D (SP-D). LPS also prevented mucous metaplasia of club cells and reduced the epidermal growth factor receptor (EGFR)-dependent mucin overproduction, with mice displaying normal breathing patterns after OVA challenge. Furthermore, the overexpression of the epithelial Th2-related molecule TSLP was blunted, and normal TSLP and IL-4 levels were found in the bronchoalveolar lavage. A lower eosinophilia was detected in LPS-pretreated mice, along with an increase in phagocytes and regulatory cells (CD4+CD25+FOXP3+ and CD4+IL-10+), together with higher levels of IL-12 and TNFα. In conclusion, our study demonstrates stable asthma-preventive epithelial effects promoted by neonatal LPS stimulation, leading to the presence of regulatory cells in the lung. These anti-allergic dynamic mechanisms would be overlaid in the epithelium, favored by an adequate epidemiological environment, during the development of asthma.

Surfactant Protein D Is Altered in Experimental Malaria-Associated Acute Lung Injury/Acute Respiratory Distress Syndrome

Surfactant protein D (SP-D) is in the collectin family of C-type lectins and plays an important role in the regulation of inflammation and the innate immune defense against pathogens. This protein has been proposed as a biomarker for acute lung injury. However, the expression of SP-D in the lung and the circulating levels of SP-D during malaria infection have received limited attention. Therefore, the aim of this study was to determine the location and expression of the SP-D protein in lung tissue and to measure the plasma level of SP-D in experimental malaria-associated acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Malaria-infected mice induced by Plasmodium berghei ANKA were classified into two groups, namely, the ALI/ARDS and non-ALI/ARDS groups, according to lung histopathology. The lungs of uninfected mice were used as a control group. The location and expression of SP-D in the lung tissues were investigated by immunohistochemical staining and Western blot analysis. In addition, the level of SP-D in plasma and lung homogenate was measured by an enzyme-linked immunosorbent assay. Immunohistochemical staining of SP-D was significantly increased in the lung tissues of the malaria-infected mice in the ALI/ARDS group compared with that in the malaria-infected mice in the non-ALI/ARDS group and the mice in the control group (p < 0.05). The levels of SP-D in the plasma and lung homogenate were significantly increased in the malaria-infected mice in the ALI/ARDS group compared with those in the malaria-infected mice in the non-ALI/ARDS group and the mice in the control group (p < 0.05). There was a significant positive correlation between SP-D in the plasma and SP-D in the lung homogenate (r _s = 0.900, p = 0.037). In conclusion, this study demonstrated increased expression levels of SP-D in the lung tissue and high levels of plasma SP-D in the malaria-infected mice with ALI/ARDS compared with those in the mice in the other groups. The current study supports that the elevation of the plasma SP-D level may provide useful biological confirmation of the diagnosis of ALI/ARDS during malaria infection.

The association of PM2.5 with airway innate antimicrobial activities of salivary agglutinin and surfactant protein D

Fine particulate matter ≤2.5 μm (PM_2.5) is a prominent global public health risk factor that can cause respiratory infection by downregulating the amounts of antimicrobial proteins and peptides (AMPs). Both salivary agglutinin (SAG) and surfactant protein D (SPD) are important AMPs in respiratory mucosal fluid, providing protection against airway pathogen invasion and infection by inducing microbial aggregation and enhancing pathogen clearance. However, the relationship between PM_2.5 and these AMPs is unclear. To better understand the relationship between PM_2.5 and airway innate immune defenses, we review the respiratory antimicrobial activities of SAG and SPD, as well as the adverse effects of PM_2.5 on airway innate antimicrobial defense. We speculate there exists a dual effect between PM_2.5 and respiratory antimicrobial activity, which means that PM_2.5 suppresses respiratory antimicrobial activity through downregulating airway AMPs, while airway AMPs accelerate PM_2.5 clearance by inducing PM_2.5 microbial aggregation. We propose further research on the relationship between PM_2.5 and these AMPs.

Systematic Review and Meta-Analysis Confirms Significant Contribution of Surfactant Protein D in Chronic Obstructive Pulmonary Disease

Background: Surfactant protein D (SFTPD) is a lung specific protein which performs several key regulatory processes to maintain overall lung function. Several infectious and immune mediated diseases have been shown to be associated with SFTPD. Recent findings have suggested the serum concentration of SFTPD can be used as a diagnostic or prognostic marker for chronic obstructive pulmonary disease (COPD) and acute exacerbation COPD (AECOPD). But these findings lack replication studies from different ethnic populations and meta-analysis, to establish SFTPD as reliable diagnostic or prognostic biomarker for COPD and associated conditions.

Methods: We performed systematic literature search based on stringent inclusion and exclusion criteria to identify eligible studies to perform a meta-analysis. Our objective was to assess the predictability of serum SFTPD concentration and SFTPD allelic conformation at rs721917 (C > T) with COPD and AECOPD outcome. These variables were compared between COPD and healthy controls, where mean difference (MD), and odds ratio (OR) were calculated to predict the overall effect size. Review manager (RevMan-v5.3) software was used to analyse the data.

Results: A total of eight published reports were included in this study. Comparative serum SFTPD concentration data were extracted from six studies and three studies were evaluated for assessment of genetic marker from SFTPD. Our study identified strong association of elevated serum SFTPD with COPD and AECOPD. Significant association of risk was also observed for “T” allele or “TT” genotype of rs721917 from SFTPD with COPD and AECOPD.

Conclusion: Serum concentration and alleleic conformation of SFTPD has a significantly high predictive value for COPD and AECOPD. Thus, these can be tested further and could be applied as a predictive or prognostic marker.

Characterization of Early Stages of Human Alveolar Infection by the Q Fever Agent Coxiella burnetii

Human Q fever is caused by the intracellular bacterial pathogen Coxiella burnetii Q fever presents with acute flu-like and pulmonary symptoms or can progress to chronic, severe endocarditis. After human inhalation, C. burnetii is engulfed by alveolar macrophages and transits through the phagolysosomal maturation pathway, resisting the acidic pH of lysosomes to form a parasitophorous vacuole (PV) in which to replicate. Previous studies showed that C. burnetii replicates efficiently in primary human alveolar macrophages (hAMs) in ex vivo human lung tissue. Although C. burnetii replicates in most cell types in vitro, the pathogen does not grow in non-hAM cells of human lung tissue. In this study, we investigated the interaction between C. burnetii and other pulmonary cell types apart from the lung environment. C. burnetii formed a prototypical PV and replicated efficiently in human pulmonary fibroblasts and in airway, but not alveolar, epithelial cells. Atypical PV expansion in alveolar epithelial cells was attributed in part to defective recruitment of autophagy-related proteins. Further assessment of the C. burnetii growth niche showed that macrophages mounted a robust interleukin 8 (IL-8), neutrophil-attracting response to C. burnetii and ultimately shifted to an M2-polarized phenotype characteristic of anti-inflammatory macrophages. Considering our findings together, this study provides further clarity on the unique C. burnetii-lung dynamic during early stages of human acute Q fever.

Effect of Glucose Improvement on Spirometric Maneuvers in Patients With Type 2 Diabetes: The Sweet Breath Study

OBJECTIVE

Type 2 diabetes exerts a deleterious effect on lung function. However, it is unknown whether an improvement in glycemic control ameliorates pulmonary function.

RESEARCH DESIGN AND METHODS

Prospective interventional study with 60 patients with type 2 diabetes and forced expiratory volume in 1 s (FEV1) ≤90% of predicted. Spirometric maneuvers were evaluated at baseline and after a 3-month period in which antidiabetic therapy was intensified. Those with an HbA_1c reduction of ≥0.5% were considered to be good responders (n = 35).

RESULTS

Good responders exhibited a significant improvement in spirometric values between baseline and the end of the study (forced vital capacity [FVC]: 78.5 ± 12.6% vs. 83.3 ± 14.7%, P = 0.029]; FEV1: 75.6 ± 15.3% vs. 80.9 ± 15.4%, P = 0.010; and peak expiratory flow [PEF]: 80.4 ± 21.6% vs. 89.2 ± 21.0%, P = 0.007). However, no changes were observed in the group of nonresponders when the same parameters were evaluated (P = 0.586, P = 0.987, and P = 0.413, respectively). Similarly, the initial percentage of patients with a nonobstructive ventilatory defect and with an abnormal FEV1 decreased significantly only among good responders. In addition, the absolute change in HbA_1c inversely correlated to increases in FEV1 (r = -0.370, P = 0.029) and PEF (r = -0.471, P = 0.004) in the responders group. Finally, stepwise multivariate regression analysis showed that the absolute change in HbA_1c independently predicted increased FEV1 (R ² = 0.175) and PEF (R ² = 0.323). In contrast, the known duration of type 2 diabetes, but not the amelioration of HbA_1c, was related to changes in forced expiratory flow between 25% and 75% of the FVC.

CONCLUSIONS

In type 2 diabetes, spirometric measurements reflecting central airway obstruction and explosive muscle strength exhibit significant amelioration after a short improvement in glycemic control.

Surfactant Protein D Reverses the Gene Signature of Transepithelial HIV-1 Passage and Restricts the Viral Transfer Across the Vaginal Barrier

Effective prophylactic strategy against the current epidemic of sexually transmitted HIV-1 infection requires understanding of the innate gatekeeping mechanisms at the genital mucosa. Surfactant protein D (SP-D), a member of the collectin family of proteins naturally present in the vaginal tract, is a potential HIV-1 entry inhibitor at the cellular level. Human EpiVaginal tissues compartmentalized in culture inserts were apically exposed to HIV-1 and/or a recombinant fragment of human SP-D (rfhSP-D) and viral passage was assessed in the basal chamber containing mononuclear leukocytes. To map the gene signature facilitating or resisting the transepithelial viral transfer, microarray analysis of the HIV-1 challenged EpiVaginal tissues was performed in the absence or presence of rfhSP-D. Mucosal biocompatibility of rfhSP-D was assessed ex vivo and in the standard rabbit vaginal irritation model. The passage of virus through the EpiVaginal tissues toward the underlying target cells was associated with a global epithelial gene signature including differential regulation of genes primarily involved in inflammation, tight junctions and cytoskeletal framework. RfhSP-D significantly inhibited HIV-1 transfer across the vaginal tissues and was associated with a significant reversal of virus induced epithelial gene signature. Pro-inflammatory NF-κB and mTOR transcripts were significantly downregulated, while expression of the tight junctions and cytoskeletal genes was upheld. In the absence of virus, rfhSP-D directly interacted with the EpiVaginal tissues and upregulated expression of genes related to structural stability of the cell and epithelial integrity. There was no increment in the viral acquisition by the PBMCs present in basal chambers wherein, the EpiVaginal tissues in apical chambers were treated with rfhSP-D. The effective concentrations of rfhSP-D had no effect on lactobacilli, epithelial barrier integrity and were safe on repeated applications onto the rabbit vaginal mucosa. This pre-clinical safety data, coupled with its efficacy of restricting viral passage via reversal of virus-induced gene expression of the vaginal barrier, make a strong argument for clinical trials of rfhSP-D as a topical anti-HIV microbicide.

Pneumoproteins in Offshore Drill Floor Workers

The aim was to assess pneumoproteins and a certain biomarker of systemic inflammation in drill floor workers exposed to airborne contaminants generated during drilling offshore, taking into consideration serum biomarkers of smoking, such as nicotine (S-Nico) and cotinine. Blood samples of club cell protein 16 (CC-16), surfactant protein D (SP-D) and C-reactive protein (CRP) were collected before and after a 14-day work period from 65 drill floor workers and 65 referents. Air samples of oil mist, drilling mud components and elemental carbon were collected in person. The drill floor workers were exposed to a median air concentration of 0.18 mg/m³ of oil mist and 0.14 mg/m³ of airborne mud particles. There were no differences in the concentrations of CC-16 and SP-D across the 14-day work period and no difference between drill floor workers and referents at baseline after adjusting for differences in sampling time and smoking. CRP decreased across the work period. There was a strong association between the CC-16 concentrations and the time of sampling. Current smokers with S-Nico > detection limit (DL) had a statistically significantly lower CC-16 concentration, while smokers with S-Nico < DL had CC-16 concentrations similar to that of the non-smokers. Fourteen days of work offshore had no effect on serum pneumoprotein and CRP concentrations. However, the time of blood sampling was observed to have a strong effect on the measured concentrations of CC-16. The effect of current smoking on the CC-16 concentrations appears to be dependent on the S-Nico concentrations.

Which Factors Associated With Activated Eosinophils Contribute to the Pathogenesis of Aspirin-Exacerbated Respiratory Disease?

Eosinophils have long been recognized as a central effector cell in the lungs of asthmatic patients. They contribute to airway inflammation and remodeling through releasing several molecules such as cytokines, granule proteins, lipid mediators and extracellular traps/vesicles. Repeated evidence reveals that intense eosinophil infiltration in upper and lower airway mucosae contributes to the pathogenesis of aspirin-exacerbated respiratory disease (AERD). Persistent eosinophilia is found to be associated with type 2 immune responses, cysteinyl leukotriene overproduction and eosinophil-epithelium interactions. This review highlights recent findings about key mechanisms of eosinophil activation in the airway inflammation of AERD. In addition, current biologics (targeting type 2 immune responses) were suggested to control eosinophilic inflammation for AERD patients.

Association of Surfactant-Associated Protein D Gene Polymorphisms with the Risk of COPD: a Meta-Analysis

The relationship between surfactant-associated protein D polymorphisms and chronic obstructive pulmonary disease risk remains controversial. This article is the first to systematically evaluate this relationship. A comprehensive worldwide search was conducted for relevant literature on surfactant-associated protein D gene mutations and chronic obstructive pulmonary disease risk prediction. Study quality was evaluated using the Newcastle-Ottawa scale. After four genetic models (the allele, additive, recessive, and dominant models) were identified, odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were applied in this meta-analysis. The meta-analysis included 659 individuals in the case group and 597 in the control group. In the Asian population, none of the four genetic models revealed any significant association between rs2243639 genotype and the risk of chronic obstructive pulmonary disease. In Caucasians, however, the recessive model exhibited significant risk associated with rs2243639. Furthermore, there was a significant association between rs721917 genotype and the risk of chronic obstructive pulmonary disease in the Asian population. In contrast, none of the four gene models revealed any significant risk associated with this gene in the Caucasian population. This meta-analysis suggests that rs2243639 is not related to the risk of chronic obstructive pulmonary disease in the Asian population but is related to this risk in the Caucasian population. Regarding rs721917, the T allele may increase the risk of chronic obstructive pulmonary disease in the Asian population.

Off-label mesenchymal stromal cell treatment in two infants with severe bronchopulmonary dysplasia: clinical course and biomarkers profile

BACKGROUND

Bronchopulmonary dysplasia (BPD) is the most prevalent sequelae of premature birth, for which therapeutic options are currently limited. Mesenchymal stromal cells (MSCs) are a potential therapy for prevention or reversal of BPD.

SERIES OF CASES

We report on two infants with severe BPD in whom off-label treatment with repeated intravenous doses of allogeneic bone marrow-derived MSCs were administered. We analyzed the temporal profile of serum and tracheal cytokines and growth factors as well as safety, tolerability and clinical response. The administration of repeated intravenous doses of MSCs in two human babies with severe and advanced BPD was feasible and safe and was associated with a decrease of pro-inflammatory molecules and lung injury biomarkers. Both patients were at very advanced stages of BPD with very severe lung fibrosis and did not survive the disease.

CONCLUSIONS

MSCs are a promising therapy for BPD, but they should be administered in early stages of the disease.

Effects of bone marrow-derived mesenchymal stromal cells on gene expression in human alveolar type II cells exposed to TNF-α, IL-1β, and IFN-γ

The acute respiratory distress syndrome (ARDS) is common in critically ill patients and has a high mortality rate. Mesenchymal stromal cells (MSCs) have demonstrated therapeutic potential in animal models of ARDS, and their benefits occur in part through interactions with alveolar type II (ATII) cells. However, the effects that MSCs have on human ATII cells have not been well studied. Using previously published microarray data, we performed genome-wide differential gene expression analyses of human ATII cells that were (1) unstimulated, (2) exposed to proinflammatory cytokines (CytoMix), or (3) exposed to proinflammatory cytokines plus MSCs. Findings were validated by qPCR. Alveolar type II cells differentially expressed hundreds of genes when exposed either to proinflammatory cytokines or to proinflammatory cytokines plus MSCs. Stimulation with proinflammatory cytokines increased expression of inflammatory genes and downregulated genes related to surfactant function and alveolar fluid clearance. Some of these changes, including expression of some cytokines and genes related to surfactant, were reversed by exposure to MSCs. In addition, MSCs induced upregulation of other potentially beneficial genes, such as those related to extracellular matrix remodeling. We confirmed several of these gene expression changes by qPCR. Thus, ATII cells downregulate genes associated with surfactant and alveolar fluid clearance when exposed to inflammatory cytokines, and mesenchymal stromal cells partially reverse many of these gene expression changes.

New Biomarkers to Diagnose Ventilator Associated Pneumonia: Pentraxin 3 and Surfactant Protein D

OBJECTIVE

To detect the most effective biomarker to confirm ventilator associated pneumonia (VAP).

METHODS

Fifty patients with VAP suspicious diagnosis and 30 healthy patients were recruited. Suspicion of VAP was established if patients met the modified CPIS score ≥ 6 points. The confirmation of VAP was defined by the quantitative culture of nonbronchoscopic bronchoalveolar lavage (BAL) >10⁵ CFU/ml of pathogenic microorganism. Serum samples for determination of C-reactive protein (CRP), procalcitonin (PCT), pentraxin 3 (PTX3), surfactant protein D (SPD) were collected on suspected VAP.

RESULTS

Twenty seven of 50 patients were accepted as confirmed VAP group whose nonbronchoscopic BAL cultures were positive and rest of them were accepted as unconfirmed VAP group. PTX3, PCT and SPD levels were significantly higher in confirmed VAP group, (P = 0.021, P = 0.007, P < 0.001 respectively). There were no significant differences in CRP levels between the two groups (P = 0.062). The most sensitive marker for diagnosing VAP was SPD (P < 0.001). Receiver operating characteristic (ROC) curve for modified clinical pulmonary infection score (CPIS) to confirm VAP was evaluated (AUC 0.741 ± 0.07, P < 0.001) and the optimal cutoff value was >7 with a sensitivity of 51.85% and a specificity of 91.3%. SPD levels were significantly higher in Acinetobacter baumannii and Pseudomonas aeruginosa infected patients than culture negative patients (P < 0.001).

CONCLUSIONS

The index findings suggest that serum SPD is the most sensitive biomarker in diagnosis of VAP and it can be used as an early and organism specific marker for Acinetobacter baumannii and Pseudomonas aeruginosa.

Pathogenesis, imaging and clinical characteristics of CF and non-CF bronchiectasis

Bronchiectasis is a common feature of severe inherited and acquired pulmonary disease conditions. Among inherited diseases, cystic fibrosis (CF) is the major disorder associated with bronchiectasis, while acquired conditions frequently featuring bronchiectasis include post-infective bronchiectasis and chronic obstructive pulmonary disease (COPD). Mechanistically, bronchiectasis is driven by a complex interplay of inflammation and infection with neutrophilic inflammation playing a predominant role. The clinical characterization and management of bronchiectasis should involve a precise diagnostic workup, tailored therapeutic strategies and pulmonary imaging that has become an essential tool for the diagnosis and follow-up of bronchiectasis. Prospective future studies are required to optimize the diagnostic and therapeutic management of bronchiectasis, particularly in heterogeneous non-CF bronchiectasis populations.

INFLUENCE OF CONCOMITANT ARTERIAL HYPERTENSION ON ACTIVITY OF INFLAMMATORY PROCESS IN PATIENTS WITH COMMUNITY-ACQUIRED PNEUMONIA

The aim of the work was to determine the diagnostic value of the markers of surfactant protein D (SP-D) and C-reactive protein (C-RP) in patients with community-acquired pneumonia (CAP) with concomitant arterial hypertension (AH) and its effects on the activity of the inflammatory process. The study included 79 people. Among them, 63 patients with CAP and 16 healthy individuals who were a control group. Depending on the presence of hypertension, the patients were divided into two groups. The first group included 26 patients with CAP with AH, the second – 37 patients with CAP without AH. All patients were given general-clinical methods of examination, radiography of the chest organs in two projections. Plasma levels of SP-D and C-RP were determined. Reliable connection (p<0.05) was determined between the presence of AH and the probability of occurrence of CAP (OR - odds ratio 2.27 [95 % CI 1.05–4.94]). The level of SP-D and C-RP in patients with AH on the first day was significantly higher than in healthy subjects (p<0.05). In patients in the first group, SP-D levels were significantly higher (p<0.05) for the first, third and ninth day relative to the second group. The existence of a direct tie of average strength between the presence of AH and SP-D (R=0.41, p<0.05) has been determined. The presence of a direct correlation link of mean strength (R=0.38; p<0.05) between the AH and the level of C-RP indicates that arterial hypertension in patients with CAP increases the activity of the systemic inflammatory response.

Altered expression of cyclooxygenase-2, 12-lipoxygenase, inducible nitric oxide synthase-2 and surfactant protein D in lungs of patients with pulmonary injury caused by sulfur mustard

CONTEXT

Sulfur mustard (SM) is a strong alkylating toxicant that targets different organs, particularly human lung tissue. Change in genes expression is one of the molecular mechanisms of SM toxicity in damaged tissue.

OBJECTIVE

The purpose of this investigation is to characterize the expression of cyclooxygenase-2 (COX-2), 12-lipoxygenase (12-LO), inducible nitric oxide synthase 2 (iNOS2), and surfactant protein D (SFTPD) in lungs of patients who exposed to SM.

METHODS

Lung biopsies were provided from SM-exposed patients (n = 6) and controls (n = 5). Total RNA were extracted from all specimens and then cDNA was synthesized for each sample. Changes in gene expression were measured using RT² Profiler ™PCR Array.

RESULTS

Pulmonary function tests revealed more obstructive and restrictive spirometric patterns among patients compared to the control group. Expression of COX-2 and 12-LO in the lung of patients was increased by 6.2555 (p = 0.004) and 6.2379-folds (p = 0.002), respectively. In contrast, expression of SF-D and iNOS genes was reduced by 8.5869-fold (p = 0.005) and 2.4466-folds (p = 0.011), respectively.

CONCLUSIONS

Mustard lungs were associated with overexpression of COX-2 and 12-LO, which are responsible for inflammation, overproduction of free radicals and oxidative stress. Downregulation of iNOS2 and SF-D are probably the reason for lung disease and dysfunction among these patients. Therefore, the expression of these genes could be an important, routine part of the management of such patients.

Surfactant protein D delays Fas- and TRAIL-mediated extrinsic pathway of apoptosis in T cells

Only a few extracellular soluble proteins are known to modulate apoptosis. We considered that surfactant-associated protein D (SP-D), an innate immune collectin present on many mucosal surfaces, could regulate apoptosis. Although SP-D is known to be important for immune cell homeostasis, whether SP-D affects apoptosis is unknown. In this study we aimed to determine the effects of SP-D on Jurkat T cells and human T cells dying by apoptosis. Here we show that SP-D binds to Jurkat T cells and delays the progression of Fas (CD95)-Fas ligand and TRAIL-TRAIL receptor induced, but not TNF-TNF receptor-mediated apoptosis. SP-D exerts its effects by reducing the activation of initiator caspase-8 and executioner caspase-3. SP-D also delays the surface exposure of phosphatidylserine. The effect of SP-D was ablated by the presence of caspase-8 inhibitor, but not by intrinsic pathway inhibitors. The binding ability of SP-D to dying cells decreases during the early stages of apoptosis, suggesting the release of apoptotic cell surface targets during apoptosis. SP-D also delays FasL-induced death of primary human T cells. SP-D delaying the progression of the extrinsic pathway of apoptosis could have important implications in regulating immune cell homeostasis at mucosal surfaces.

Plasma surfactant protein-D as a diagnostic biomarker for acute respiratory distress syndrome: validation in US and Korean cohorts

BACKGROUND

Acute respiratory distress syndrome (ARDS) is potentially underrecognized by clinicians. Early recognition and subsequent optimal treatment of patients with ARDS may be facilitated by usage of biomarkers. Surfactant protein D (SP-D), a marker of alveolar epithelial injury, has been proposed as a potentially useful biomarker for diagnosis of ARDS in a few studies. We tried to validate the performance of plasma SP-D levels for diagnosis of ARDS.

METHODS

We conducted a retrospective analysis using data from three (two in USA and one in Korea) prospective biobank cohorts involving 407 critically ill patients admitted to medical intensive care unit (ICU). A propensity score matched analysis (patients with versus without ARDS, matched 1:1) was carried out using significant variables from multiple logistic regression. The diagnostic accuracy of plasma SP-D as a diagnostic marker of ARDS was assessed by receiver operating characteristic curve analysis.

RESULTS

Out of the 407 subjects included in this study, 39 (10%) patients fulfilled ARDS criteria. Patients with ARDS had higher SP-D levels in plasma (p < 0.01) and higher hospital-mortality (p < 0.001) than those without ARDS. Thirty eight subjects with ARDS (cases) were successfully matched for propensity for ARDS with 38 subjects without ARDS (controls). Plasma levels of SP-D were higher in cases with ARDS compared to their matched controls without ARDS [median 20.8 ng/mL (interquartile range, 12.7-38.4) versus 7.9 (4.1-17.0); p = 0.001]. The area under the receiver operating characteristic curve for SP-D for the diagnosis of ARDS was 0.71 (95% confidence intervals, 0.60-0.83). A cut-off point of 12.7 ng/mL for SP-D yielded sensitivity of 74% and specificity of 63%.

CONCLUSIONS

High levels of SP-D within 48 h after ICU admission might serve as a diagnostic marker for ARDS in patients hospitalized in medical ICU. Further prospective trials are required to validate the diagnostic role of SP-D in ARDS, and if its usefulness is greater in direct than in indirect ARDS, as well as across different strata of severity of ARDS.

Serum Surfactant Protein D as a Biomarker for Measuring Lung Involvement in Obese Patients With Type 2 Diabetes

CONTEXT

Lung impairment is a new target for late diabetic complications. Biomarkers that could help identify patients requiring functional respiratory tests have not been reported.

OBJECTIVE

Our aim was to examine whether serum surfactant protein D (SP-D) and A (SP-A) could be useful biomarkers of lung damage in obese patients with type 2 diabetes (T2D) without known lung disease.

DESIGN AND SETTING

A case-control study conducted in an ambulatory obesity unit.

PATIENTS

Forty-nine obese patients with T2D and 98 subjects without diabetes matched by age, sex, body mass index, and waist circumference were included.

INTERVENTIONS

Serum SP-D and SP-A levels were measured using enzyme-linked immunosorbent assay. Forced spirometry and static pulmonary volume were assessed.

RESULTS

Patients with T2D exhibited higher serum SP-D concentrations than control subjects (P = 0.006). No differences in serum SP-A concentrations were observed. There was an inverse association between forced expiratory volume in 1 second (FEV1) and serum SP-D (r = -0.265; P = 0.029), as well as a significant positive relationship between SP-D concentration and residual volume (r = 0.293; P = 0.043). From receiver operating characteristic analysis, the best SP-D cutoff to identify a FEV1 <80% of predicted was 132.3 ng/mL (area under the curve, 0.725; sensitivity, 77.7%; specificity, 69.4%). Stepwise multivariate regression analysis showed that serum SP-D concentration ≥132.3 ng/mL was independently associated with a FEV1 <80% of predicted (R2 = 0.406). Only the existence of T2D contributed independently to serum SD-P variance among all subjects (R2 = 0.138).

CONCLUSIONS

Serum SP-D concentration can be a useful biomarker for detecting lung impairment in obese patients with T2D.

Surfactant protein D multimerization and gene polymorphism in COPD and asthma

BACKGROUND AND OBJECTIVE

A structural single nucleotide polymorphism rs721917 in the surfactant protein D (SP-D) gene, known as Met11Thr, was reported to influence the circulating levels and degree of multimerization of SP-D and was associated with both COPD and atopy in asthma. Moreover, disease-related processes are known to degrade multimerized SP-D, however, the degree of the protein degradation in these diseases is not clarified. We aimed to determine the distribution of multimerized (high molecular weight (HMW)) and non-multimerized (low molecular weight (LMW)) species of serum SP-D and their correlation with genetic polymorphisms and presence of disease in Lebanese COPD and asthmatic patients.

METHODS

Serum SP-D levels were measured by ELISA in 88 COPD, 121 asthmatic patients and 223 controls. Randomly selected subjects were chosen for genotyping of rs721917 and multimerization studies. HMW and LMW SP-D were separated by gel permeation chromatography.

RESULTS

Serum SP-D levels were significantly increased in patients with COPD, but not in asthmatic patients, when compared to controls. Met11Thr variation strongly affected serum SP-D levels and the degree of multimerization, but was not associated with COPD and asthma in the study. Remarkably, HMW/LMW serum SP-D ratio was significantly lower in Met11/Met11 COPD and asthmatic patients compared to controls.

CONCLUSION

Collectively, non-multimerized species of serum SP-D were dominant in COPD and asthmatic patients suggesting that degradation of SP-D takes place to a significant degree in pulmonary disease. Assays that can separate SP-D proteolytic breakdown products or modified forms from naturally occurring SP-D trimers may result in optimal disease markers for pulmonary inflammatory diseases.

A pilot clinical trial of recombinant human angiotensin-converting enzyme 2 in acute respiratory distress syndrome

Background

Renin-angiotensin system (RAS) signaling and angiotensin-converting enzyme 2 (ACE2) have been implicated in the pathogenesis of acute respiratory distress syndrome (ARDS). We postulated that repleting ACE2 using GSK2586881, a recombinant form of human angiotensin-converting enzyme 2 (rhACE2), could attenuate acute lung injury.

Methods

We conducted a two-part phase II trial comprising an open-label intrapatient dose escalation and a randomized, double-blind, placebo-controlled phase in ten intensive care units in North America. Patients were between the ages of 18 and 80 years, had an American-European Consensus Criteria consensus diagnosis of ARDS, and had been mechanically ventilated for less than 72 h. In part A, open-label GSK2586881 was administered at doses from 0.1 mg/kg to 0.8 mg/kg to assess safety, pharmacokinetics, and pharmacodynamics. Following review of data from part A, a randomized, double-blind, placebo-controlled investigation of twice-daily doses of GSK2586881 (0.4 mg/kg) for 3 days was conducted (part B). Biomarkers, physiological assessments, and clinical endpoints were collected over the dosing period and during follow-up.

Results

Dose escalation in part A was well-tolerated without clinically significant hemodynamic changes. Part B was terminated after 39 of the planned 60 patients following a planned futility analysis. Angiotensin II levels decreased rapidly following infusion of GSK2586881, whereas angiotensin-(1–7) and angiotensin-(1–5) levels increased and remained elevated for 48 h. Surfactant protein D concentrations were increased, whereas there was a trend for a decrease in interleukin-6 concentrations in rhACE2-treated subjects compared with placebo. No significant differences were noted in ratio of partial pressure of arterial oxygen to fraction of inspired oxygen, oxygenation index, or Sequential Organ Failure Assessment score.

Conclusions

GSK2586881 was well-tolerated in patients with ARDS, and the rapid modulation of RAS peptides suggests target engagement, although the study was not powered to detect changes in acute physiology or clinical outcomes.

Trial registration

ClinicalTrials.gov, NCT01597635. Registered on 26 January 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1823-x) contains supplementary material, which is available to authorized users.

Importance of serial changes in biomarkers in idiopathic pulmonary fibrosis

The clinical significance of serial changes in serum biomarkers in patients with idiopathic pulmonary fibrosis (IPF) remains to be established. This retrospective study was conducted to clarify the associations of serial changes in serum Krebs von den Lungen-6 (KL-6) and surfactant protein-D (SP-D) with changes in physiological indices and overall mortality in IPF. The study subjects were 75 patients with IPF. The 6 month change in serum KL-6 was significantly correlated with changes in the percentage of the predicted forced vital capacity (FVC % pred) and the percentage of the predicted diffusing capacity of the lung for carbon monoxide (% D_LCO), while the 6 month change in serum SP-D was correlated only with % D_LCO. During the mean follow-up period of 647 days, 22 (29.3%) patients died. An increase in serum KL-6 over a 6 month period was a significant predictor of mortality even after adjustment for %FVC, % D_LCO and serum KL-6 at the baseline (hazard ratio 1.10 per 100 U·mL^-1, 95% CI 1.01-1.18, p=0.03), whereas the 6 month increase in serum SP-D was not significant. Serial measurements of serum KL-6 may provide additional prognostic information compared to that provided by physiological parameters in patients with IPF.

Surfactant protein-D predicts prognosis of interstitial lung disease induced by anticancer agents in advanced lung cancer: a case control study

BACKGROUND

Interstitial lung diseases induced by anticancer agents (ILD-AA) are rare adverse effects of anticancer therapy. However, prognostic biomarkers for ILD-AA have not been identified in patients with advanced lung cancer. Our aim was to analyze the association between serum biomarkers sialylated carbohydrate antigen Krebs von den Lungen-6 (KL-6) and surfactant protein D (SP-D), and clinical characteristics in patients diagnosed with ILD-AA.

METHODS

Between April 2011 and March 2016, 1224 advanced lung cancer patients received cytotoxic agents and epidermal growth factor receptor tyrosine kinase inhibitors at Juntendo University Hospital and Juntendo University Urayasu Hospital. Of these patients, those diagnosed with ILD-AA were enrolled in this case control study. ΔKL-6 and ΔSP-D were defined as the difference between the levels at the onset of ILD-AA and their respective levels prior to development of ILD-AA. We evaluated KL-6 and SP-D at the onset of ILD-AA, ΔKL-6 and ΔSP-D, the risk factors for death related to ILD-AA, the chest high resolution computed tomography (HRCT) findings, and survival time in patients diagnosed with ILD-AA.

RESULTS

Thirty-six patients diagnosed with ILD-AA were enrolled in this study. Among them, 14 patients died of ILD-AA. ΔSP-D in the patients who died was significantly higher than that in the patients who survived. However, ΔKL-6 did not differ significantly between the two groups. Moreover, ΔSP-D in patients who exhibited diffuse alveolar damage was significantly higher than that in the other patterns on HRCT. Receiver operating characteristic curve analysis was used to set the optimal cut off value for ΔSP-D at 398 ng/mL. Survival time for patients with high ΔSP-D (≥ 398 ng/mL) was significantly shorter than that for patients with low ΔSP-D. Multivariate analysis revealed that ΔSP-D was a significant prognostic factor of ILD-AA.

CONCLUSIONS

This is the first research to evaluate high ΔSP-D (≥ 398 ng/mL) in patients with ILD-AA and to determine the risk factors for ILD-AA in advanced lung cancer patients. ΔSP-D might be a serum prognostic biomarker of ILD-AA. Clinicians should evaluate serum SP-D during chemotherapy and should carefully monitor the clinical course in patients with high ΔSP-D.

Surfactant Protein-D: A sensitive predictor for efficiency of preoperative pulmonary rehabilitation

BACKGROUND

Surfactant Protein D (SP-D) as a lung-derived biomarker for inflammatory lung disease is being studied in depth. Meanwhile, the Pre-operative Rehabilitation Program (PRP) has been proposed as an effective treatment to reduce the incidence of Post-operative Pulmonary Complications (PPCs) and further improve quality of life. However, the relationship between serum SP-D levels and PRP remains unclear. This study aimed to explore the correlation between these two phenomena and validate the feasibility of using preoperative serum SP-D levels to predict or assess the effectiveness of PRP.

METHODS

A prospective study with a total of 80 lung cancer patients with risk factors for PPCs was conducted; subjects were randomly divided into an Intervention Group (IG, n = 36) and a Control Group (CG, n = 44). The IG was treated with one week of PRP, and the CG was treated for the same duration with routine preoperative preparation before the lobectomy. Peripheral venous blood samples were collected at five time points and serum SP-D levels were measured by enzyme-linked immunosorbent assay (ELISA). We analysed the serum level changes of SP-D as well as the PPCs occurred between the two groups.

RESULTS

Both groups were comparable at baseline. The average levels of SP-D in both groups showed a decline trend with time, and levels before the day of surgery revealed a significant decline range in the IG compared with the CG (6.56 ± 5.30 vs. 1.05 ± 2.79 ng/ml, P < 0.001). The incidence of PPCs in the IG was significantly lower than in the CG (2/36 vs. 10/44, p = 0.032), as were the PPC person-times occurring from postoperative days 1-4 (POD 1-4) (5/36 vs. 15/44, p = 0.038) and the total person-times (5/36 vs. 19/44, p = 0.004). The overall SP-D levels on the day before surgery in patients with PPCs were significantly higher than those without PPCs (34.07 ± 4.32 vs. 30.30 ± 6.52 ng/ml, p = 0.005); furthermore, the overall SP-D levels on admission day in CG patients with PPCs were also significantly higher than those without PPCs (34.93 ± 4.15 vs. 29.81 ± 7.47 ng/ml, p = 0.045).

CONCLUSIONS

The Preoperative Intensity Rehabilitation Program could positively decrease the serum SP-D levels in lung cancer patients with PPC risk factors, and higher preoperative serum SP-D levels may related to a higher incidence of PPCs. Serum SP-D may be a potential predictor for evaluating the efficiency of PRPs and the risk of PPC occurrence.

Variable ventilation improves pulmonary function and reduces lung damage without increasing bacterial translocation in a rat model of experimental pneumonia

Background

Variable ventilation has been shown to improve pulmonary function and reduce lung damage in different models of acute respiratory distress syndrome. Nevertheless, variable ventilation has not been tested during pneumonia. Theoretically, periodic increases in tidal volume (V_T) and airway pressures might worsen the impairment of alveolar barrier function usually seen in pneumonia and could increase bacterial translocation into the bloodstream. We investigated the impact of variable ventilation on lung function and histologic damage, as well as markers of lung inflammation, epithelial and endothelial cell damage, and alveolar stress, and bacterial translocation in experimental pneumonia.

Methods

Thirty-two Wistar rats were randomly assigned to receive intratracheal of Pseudomonas aeruginosa (PA) or saline (SAL) (n = 16/group). After 24-h, animals were anesthetized and ventilated for 2 h with either conventional volume-controlled (VCV) or variable volume-controlled ventilation (VV), with mean V_T = 6 mL/kg, PEEP = 5cmH₂O, and FiO₂ = 0.4. During VV, tidal volume varied randomly with a coefficient of variation of 30% and a Gaussian distribution. Additional animals assigned to receive either PA or SAL (n = 8/group) were not ventilated (NV) to serve as controls.

Results

In both SAL and PA, VV improved oxygenation and lung elastance compared to VCV. In SAL, VV decreased interleukin (IL)-6 expression compared to VCV (median [interquartile range]: 1.3 [0.3–2.3] vs. 5.3 [3.6–7.0]; p = 0.02) and increased surfactant protein-D expression compared to NV (2.5 [1.9–3.5] vs. 1.2 [0.8–1.2]; p = 0.0005). In PA, compared to VCV, VV reduced perivascular edema (2.5 [2.0–3.75] vs. 6.0 [4.5–6.0]; p < 0.0001), septum neutrophils (2.0 [1.0–4.0] vs. 5.0 [3.3–6.0]; p = 0.0008), necrotizing vasculitis (3.0 [2.0–5.5] vs. 6.0 [6.0–6.0]; p = 0.0003), and ultrastructural lung damage scores (16 [14–17] vs. 24 [14–27], p < 0.0001). Blood colony-forming-unit (CFU) counts were comparable (7 [0–28] vs. 6 [0–26], p = 0.77). Compared to NV, VCV, but not VV, increased expression amphiregulin, IL-6, and cytokine-induced neutrophil chemoattractant (CINC)-1 (2.1 [1.6–2.5] vs. 0.9 [0.7–1.2], p = 0.025; 12.3 [7.9–22.0] vs. 0.8 [0.6–1.9], p = 0.006; and 4.4 [2.9–5.6] vs. 0.9 [0.8–1.4], p = 0.003, respectively). Angiopoietin-2 expression was lower in VV compared to NV animals (0.5 [0.3–0.8] vs. 1.3 [1.0–1.5], p = 0.01).

Conclusion

In this rat model of pneumonia, VV improved pulmonary function and reduced lung damage as compared to VCV, without increasing bacterial translocation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-016-0476-7) contains supplementary material, which is available to authorized users.

Collectins, H-ficolin and LL-37 reduce influence viral replication in human monocytes and modulate virus-induced cytokine production

Infiltrating activated monocytes are important mediators of damaging inflammation during influenza A virus (IAV) infection. We show that soluble respiratory proteins [collectins, surfactant proteins D (SP-D) and mannose binding lectin (MBL), H-ficolin and LL-37] inhibit replication of seasonal IAV in human monocytes. The collectins and H-ficolin also increased viral uptake by the cells, while LL-37 did not. H-ficolin was able to inhibit replication of the 2009 pandemic H1N1 strain (Cal09) in monocytes, but SP-D and LL-37 had significantly fewer inhibitory effects on this strain than on seasonal IAV. All of these proteins reduced IAV-induced TNF-α production, even in instances when viral replication was not reduced. We used modified recombinant versions of SP-D, MBL and ficolin to elucidate mechanisms through which these proteins alter monocyte interactions with IAV. We demonstrate the importance of the multimeric structure, and of binding properties of the lectin domain, in mediating antiviral and opsonic activity of the proteins. Hence, soluble inhibitors present in airway lining fluid may aid clearance of IAV by promoting monocyte uptake of the virus, while reducing viral replication and virus-induced TNF-α responses in these cells. However, SP-D and LL-37 have reduced ability to inhibit replication of pandemic IAV in monocytes.

Ipr1 modified BCG as a novel vaccine induces stronger immunity than BCG against tuberculosis infection in mice

Tuberculosis is a major challenge to global public health. However, the Bacille Calmette‑Guérin (BCG), the only vaccine available against tuberculosis, has been questioned for the low protective effect. The present study used the mouse gene intracellular pathogen resistance I (Ipr1) gene to alter the current BCG vaccine and evaluated its immunity effect against tuberculosis. This study also investigated the intrinsic relationships of Ipr1 and innate immunity. The reformed BCG (BCGi) carrying the Ipr1 gene was constructed. The mice were intranasally challenged with the M. tuberculosis H37Rv strain after vaccination with BCGi. Protection efficacy of the vaccine was assessed by the organ coefficient, bacterial load and pathological changes in the lung. The differential expression of 113 immune‑related genes between BCGi and BCG groups were detected by an oligo microarray. According to the results of organ coefficient, bacterial load and pathological changes in the organization, BCGi had been shown to have stronger protective effects against M. tuberculosis than BCG. The oligo microarray and reverse transcription‑quantitative polymerase chain reaction further revealed that the Ipr1 gene could upregulate the expression of 13 genes, including a >3‑fold increase in Toll‑like receptor (TLR)4 and 10‑fold increase in surfactant protein D (sftpd). The two genes not only participate in innate immunity against pathogens, but also are closely interrelated. Ipr1 could activate the TLR4 and sftpd signaling pathway and improve the innate immunity against tuberculosis, therefore Ipr1 modified BCG may be a candidate vaccine against M. tuberculosis.