Pharmacotherapy for acute respiratory distress syndrome

Total terpenoids of Inula japonica activated the Nrf2 receptor to alleviate the inflammation and oxidative stress in LPS-induced acute lung injury

BACKGROUND

Acute lung injury (ALI) is a life-threatening lung disease and characterized by pulmonary edema and atelectasis. Inula japonica Thunb. is a commonly used traditional Chinese medicine for the treatment of lung diseases. However, the potential effect and mechanism of total terpenoids of I. japonica (TTIJ) on ALI remain obscure.

PURPOSE

This study focused on the protective effect of TTIJ on lipopolysaccharide (LPS)-induced ALI in mice and its potential mechanism.

STUDY DESIGN AND METHODS

A mouse model of ALI was established by intratracheal instillation of LPS to investigate the protective effect of TTIJ. RNA-seq and bioinformatics were then performed to reveal the underlying mechanism. Finally, western blot and real-time qPCR were used to verify the effects of TTIJ on the inflammation and oxidative stress.

RESULTS

TTIJ notably attenuated LPS-induced histopathological changes of lung. The RNA-seq result suggested that the protective effect of TTIJ on LPS-induced ALI were associated with the Toll-like receptor 4 (TLR4) and nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling pathways. Pretreatment with TTIJ significantly reduced the inflammation and oxidative stress via regulating levels of pro-inflammatory and anti-oxidative cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), superoxide dismutase (SOD), and glutathione (GSH), in LPS-induced ALI mice. TTIJ treatment could suppress the cyclooxygenase-2 (COX-2) expression level and the phosphorylation of p65, p38, ERK, and JNK through the inactivation of the MAPK/NF-κB signaling pathway in a TLR4-independent manner. Meanwhile, TTIJ treatment upregulated expression levels of proteins involved in the Nrf2 signaling pathway, such as heme oxygenase-1 (HO-1), NAD(P)H: quinoneoxidoreductase-1 (NQO-1), glutamate-cysteine ligase catalytic subunit (GCLC), and glutamate-cysteine ligase modifier subunit (GCLM), via activating the Nrf2 receptor, which was confirmed by the luciferase assay.

CONCLUSION

TTIJ could activate the Nrf2 receptor to alleviate the inflammatory response and oxidative stress in LPS-induced ALI mice, which suggested that TTIJ could serve as the potential agent in the treatment of ALI.

Inhibition of KLF6 reduces the inflammation and apoptosis of type II alveolar epithelial cells in acute lung injury

BACKGROUND

The development of acute lung injury (ALI) into a severe stage leads to acute respiratory distress syndrome (ARDS). The morbidity and mortality of ALI and ARDS are very high. Objective: This study is aimed to explore the effect of Krüppel-like factor 6 (KLF6) on lipopolysaccharide (LPS)-induced type II alveolar epithelial cells in ALI by interacting with cysteine-rich angiogenic inducer 61 (CYR61).

MATERIAL AND METHODS

ALI mice model and LPS-induced type II alveolar epithelial cells were conducted to simulate ALI in vivo and in vitro. The messenger RNA (mRNA) and protein expression of KLF6 in lung tissues were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. Pathological changes in lung tissues were observed by hematoxylin and eosin (H&E) staining. The viability and KLF6 expression of A549 cells treated with different concentrations of LPS were detected by cell counting kit-8 (CCK-8) assay, RT-qPCR, and Western blot analysis. After indicated treatment, the viability and apoptosis of A549 cells were analyzed by CCK-8 and TUNEL assays, and the inflammation factors of A549 cells were detected by Enzyme-linked-immunosorbent serologic assay, RT-qPCR, and Western blot analysis. The combination of KLF6 and CYR61 was determined by chromatin immunoprecipitation (ChIP)-PCR and dual-luciferase reporter assay.

RESULTS

KLF6 expression was increased in lung tissues of ALI mice and LPS-induced A549 cells. Interference with KLF6 improved the viability, reduced the inflammatory damage, and promoted the apoptosis of LPS-induced A549 cells. In addition, KLF6 could bind to CYR61. Interference with KLF6 could decrease CYR61 expression in LPS-induced A549 cells. LPS also enhanced the TLR4/MYD88 signaling pathway, which was reversed by KLF6 interference. The above phenomena in LPS-induced A549 cells transfected with Si-KLF6 could be reversed by overexpression of CYR61.

CONCLUSION

Inhibition of KLF6 promoted the viability and reduced the inflammation and apoptosis of LPS-induced A549 cells, which was reversed by CYR61.

Molecular hydrogen is a potential protective agent in the management of acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome, which is a more severe form of ALI, are life-threatening clinical syndromes observed in critically ill patients. Treatment methods to alleviate the pathogenesis of ALI have improved to a great extent at present. Although the efficacy of these therapies is limited, their relevance has increased remarkably with the ongoing pandemic caused by the novel coronavirus disease 2019 (COVID-19), which causes severe respiratory distress syndrome. Several studies have demonstrated the preventive and therapeutic effects of molecular hydrogen in the various diseases. The biological effects of molecular hydrogen mainly involve anti-inflammation, antioxidation, and autophagy and cell death modulation. This review focuses on the potential therapeutic effects of molecular hydrogen on ALI and its underlying mechanisms and aims to provide a theoretical basis for the clinical treatment of ALI and COVID-19.

Evaluation of Continuous Inhaled Epoprostenol in the Treatment of Acute Respiratory Distress Syndrome, Including Patients With SARS-CoV-2 Infection

Background

Acute respiratory distress syndrome (ARDS) management is primarily supportive. Pulmonary vasodilators, such as inhaled epoprostenol (iEPO), have been shown to improve PaO2:FiO2 (PF) and are used as adjunctive therapy.

Objective

To identify the positive response rate and variables associated with response to iEPO in adults with ARDS. A positive response to iEPO was defined as a 10% improvement in PF within 6 hours.

Methods

This retrospective study included adults with ARDS treated with iEPO. The primary endpoint was the variables associated with a positive response to iEPO. Secondary endpoints were positive response rate and the change in PF and SpO2:FiO2 within 6 hours. Statistical analysis included multivariable regression.

Results

Three hundred thirty-one patients were included. As baseline PF increased, the odds of responding to iEPO decreased (odds ratio [OR], 0.752, 95% CI, 0.69-0.819, p < 0.001). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related ARDS (OR 0.478, 95% CI, 0.281-0.814, p = 0.007) was associated with decreased odds of a positive response to iEPO. The total population had a 68.3% positive response rate to iEPO. SARS-CoV-2-related ARDS and non-SARS-CoV-2-related ARDS had a 59.5% and 72.7% positive response rate, respectively. iEPO significantly improved PF (71 vs 95, P < 0.001) in the whole population.

Conclusion and Relevance

iEPO was associated with a positive effect in a majority of moderate-to-severe ARDS patients, including patients with SARS-CoV-2-related ARDS. Lower baseline PF and non-SARS-CoV-2-related ARDS were significantly associated with a positive response to iEPO. The ability to predict which patients will respond to iEPO can facilitate better utilization.

Quality of life following adult veno-venous extracorporeal membrane oxygenation for acute respiratory distress syndrome: a systematic review

BACKGROUND

Veno-venous extracorporeal membrane oxygenation (VV-ECMO) has been used successfully for the past decade in adult patients with acute respiratory distress syndrome (ARDS) refractory to conventional ventilatory support. However, knowledge of the health-related quality of life (HRQoL) in VV-ECMO patients is still limited. Thus, this study aimed to provide a comprehensive overview of the HRQoL following VV-ECMO support in ARDS patients.

METHODS

A systematic search was performed on PubMed and Web of Science databases from January 1st, 2009 to October 19th, 2020. Studies reporting on HRQoL following VV-ECMO for ARDS in adults were included. Two authors independently selected studies, extracted data, and assessed methodological quality.

RESULTS

Eight studies were eligible for inclusion, consisting of seven observational studies and one randomized controlled trial (total N = 441). All eight studies had a quantitative design and reported 265 VV-ECMO survivors to have a reduced HRQoL compared to a generally healthy population. Follow-up time varied between six months to three years. Additionally, only four studies (total N = 335) compared the HRQoL of VV-ECMO (N = 159) to conventionally treated survivors (N = 176), with one study showing a significantly better HRQoL in VV-ECMO survivors, while three studies were stating comparable HRQoL across groups. Notably, most survivors in these studies appeared to experience varying degrees of anxiety, depression, and post-traumatic stress disorder (PTSD).

CONCLUSIONS

ARDS survivors supported by VV-ECMO have a decline in HRQoL and suffered from physical and psychological impairments. This HRQoL reduction is comparable or even better to the HRQoL in conventionally treated ARDS survivors.

Potential role for furosemide in the treatment of acute respiratory distress syndrome (ARDS) and an unusual presentation of pulmonary embolism in a complex patient

An 81-year-old woman was admitted to our hospital after experiencing syncope. She was diagnosed with a large pulmonary embolism and was hemodynamically unstable therefore requiring endotracheal intubation and norepinephrine support. She presented with an upper gastrointestinal bleed which prevented her from receiving tissue plasminogen activator. She was treated with enoxaparin and ceftriaxone. Her blood, sputum and urine cultures were negative. When transferred to our ward, her antibiotic treatment was changed to piperacillin–tazobactam. A lumbar puncture was not suggestive of a central nervous system infection. Chest X-rays demonstrated rapid advancement of diffuse bilateral infiltrates which were not present at first and were interpreted by radiology consultation as suggestive of acute respiratory distress syndrome. An echocardiography showed right ventricle dilatation without left-sided heart failure. Diuretics were added and with this treatment, a quick respiratory improvement was noted as she regained consciousness and extubated shortly after.

MicroRNA dysregulation in lung injury: the role of the miR-26a/EphA2 axis in regulation of endothelial permeability

MicroRNAs (miRNAs) are noncoding RNAs that regulate gene expression in many diseases, although the contribution of miRNAs to the pathophysiology of lung injury remains obscure. We hypothesized that dysregulation of miRNA expression drives the changes in key genes implicated in the development of lung injury. To test our hypothesis, we utilized a model of lung injury induced early after administration of intratracheal bleomycin (0.1 U). Wild-type mice were treated with bleomycin or PBS, and lungs were collected at 4 or 7 days. A profile of lung miRNA was determined by miRNA array and confirmed by quantitative PCR and flow cytometry. Lung miR-26a was significantly decreased 7 days after bleomycin injury, and, on the basis of enrichment of predicted gene targets, it was identified as a putative regulator of cell adhesion, including the gene targets EphA2, KDR, and ROCK1, important in altered barrier function. Lung EphA2 mRNA, and protein increased in the bleomycin-injured lung. We further explored the miR-26a/EphA2 axis in vitro using human lung microvascular endothelial cells (HMVEC-L). Cells were transfected with miR-26a mimic and inhibitor, and expression of gene targets and permeability was measured. miR-26a regulated expression of EphA2 but not KDR or ROCK1. Additionally, miR-26a inhibition increased HMVEC-L permeability, and the disrupted barrier integrity due to miR-26a was blocked by EphA2 knockdown, shown by VE-cadherin staining. Our data suggest that miR-26a is an important epigenetic regulator of EphA2 expression in the pulmonary endothelium. As such, miR-26a may represent a novel therapeutic target in lung injury by mitigating EphA2-mediated changes in permeability.

Synthesis and evaluation of 2-cyano-3, 12-dioxooleana-1, 9(11)-en-28-oate-13β, 28-olide as a potent anti-inflammatory agent for intervention of LPS-induced acute lung injury

The present study was designed to synthesize 2-Cyano-3, 12-dioxooleana-1, 9(11)-en-28-oate-13β, 28-olide (1), a lactone derivative of oleanolic acid (OA) and evaluate its anti-inflammatory activity. Compound 1 significantly diminished nitric oxide (NO) production and down-regulated the mRNA expression of iNOS, COX-2, IL-6, IL-1β, and TNF-α in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Further in vivo studies in murine model of LPS-induced acute lung injury (ALI) showed that 1 possessed more potent protective effects than the well-known anti-inflammatory drug dexamethasone by inhibiting myeloperoxidase (MPO) activity, reducing total cells and neutrophils, and suppressing inflammatory cytokines expression, and thus ameliorating the histopathological conditions of the injured lung tissue. In conclusion, compound 1 could be developed as a promising anti-inflammatory agent for intervention of LPS-induced ALI.

Long-Term Quality of Life After Extracorporeal Membrane Oxygenation in ARDS Survivors: Systematic Review and Meta-Analysis

PURPOSE

Extracorporeal membrane oxygenation (ECMO) is an increasingly prevalent treatment for acute respiratory failure (ARF). To evaluate the impact of ECMO support on long-term outcomes for critically ill adults with ARF.

METHODS

We searched electronic databases 1948 through to November 30 2016; selected controlled trials or observational studies of critically ill adults with acute respiratory distress syndrome, examining long-term morbidity specifically health-related quality of life (HRQL); 2 authors independently selected studies, extracted data, and assessed methodological quality.

ANALYSIS

Of the 633 citations, 1 randomized controlled trial and 5 observational studies met the selection criteria. Overall quality of observational studies was moderate to high (mean score on Newcastle-Ottawa scale, 7.2/9; range, 6-8). In 3 studies (n = 245), greater decrements in HRQL were seen for survivors of ECMO when compared to survivors of conventional mechanical ventilation (CMV) as measured by the Short Form 36 (SF-36) scores ([ECMO-CMV]: 5.40 [95% confidence interval, CI, 4.11 to 6.68]). As compared to CMV survivors, those who received ECMO experienced significantly less psychological morbidity (2 studies; n = 217 [ECMO-CMV]: mean weighted difference [MWD], -1.31 [95% CI, -1.98 to -0.64] for depression and MWD, -1.60 [95% CI, -1.80 to -1.39] for anxiety).

CONCLUSIONS

Further studies are required to confirm findings and determine prognostic factors associated with more favorable outcomes in survivors of ECMO.

8,9-Dehydrohispanolone-15,16-lactol diterpene prevents LPS-triggered inflammatory responses by inhibiting endothelial activation

Endothelial activation contributes to lung inflammatory disorders by inducing leucocyte recruitment to pulmonary parenchyma. Consequently, vascular-targeted therapies constitute promising strategies for the treatment of inflammatory pathologies. In the present study, we evaluated the effect of 8,9-dehydrohispanolone-15,16-lactol diterpene (DT) on lung endothelium during inflammation. Lung endothelial cells pre-treated with DT and activated with lipopolysaccharide (LPS) or tumour necrosis factor-α (TNF-α) exhibited reduced expression of the pro-inflammatory cytokines Cxcl10, Ccl5 and Cxcl1, whereas the anti-inflammatory molecules IL1r2 and IL-10 were induced. Consistent with this result, DT pre-treatment inhibited nuclear factor κB (NF-κB) nuclear translocation, by interfering with IκBα phosphorylation, and consequently NF-κB transcriptional activity in endothelium activated by LPS or TNF-α. Furthermore, DT, probably through p38 signalling, induced transcriptional activation of genes containing activator protein 1 (AP-1)-binding elements. Inhibition of p38 prevented IL1r2 mRNA expression in endothelium incubated with DT alone or in combination with LPS or TNF-α. Accordingly, conditioned medium (CM) from these cells failed to stimulate leucocytes as measured by a reduction in adhesive ability of the leucocyte cell line J774 to fibronectin (FN). Additionally, DT reduced the expression of the endothelial adhesion molecules E-selectin, vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) after activation. Similarly, expression of VCAM-1 and ICAM-1 molecules on the lung endothelial layer of C57/BL6 mice pre-treated with DT and challenged with LPS were unchanged. Finally, inhibition of vascular adhesion molecule expression by DT decreased the interaction of J774 cells with lung endothelial cells in an inflammatory environment. Our findings establish DT as a novel endothelial inhibitor for the treatment of inflammatory-related diseases triggered by Gram-negative bacteria or by the associated cytokine TNF-α.

Treatment with the hyaluronic Acid synthesis inhibitor 4-methylumbelliferone suppresses LPS-induced lung inflammation

Exposure to bacterial endotoxins, such as lipopolysaccharide (LPS), can lead to the induction of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). To date, there are no known effective treatments for LPS-induced inflammation. In the current study, we investigated the potential use of the hyaluronic acid (HA) synthesis inhibitor 4-methylumbelliferone (4-MU) on LPS-induced acute lung inflammation. Culturing LPS-activated immune cells with 4-MU led to reduced proliferation, reduced cytokine production, and an increase in apoptosis when compared to untreated cells. Treatment of mice with 4-MU led to protection from LPS-induced lung injury. Specifically, 4-MU treatment led to a reduction in LPS-induced hyaluronic acid synthase (HAS) messenger RNA (mRNA) levels, reduction in lung permeability, and reduction in proinflammatory cytokine production. Taken together, these results suggest that use of 4-MU to target HA production may be an effective treatment for the inflammatory response following exposure to LPS.

Resistance to rocuronium and cisatracurium in a patient with a spinal injury and acute respiratory distress syndrome

PURPOSE

A case of resistance to rocuronium and cisatracurium in a patient with a spinal injury who developed acute respiratory distress syndrome (ARDS) is reported.

SUMMARY

A 34-year-old, 88-kg Caucasian man with a history of polysubstance abuse fell from a bridge approximately 30-ft high, landing head first in about 2-3 ft of water. The patient sustained anterior subluxation at cervical spine levels C5-C6 and severe spinal canal compromise with cord compression and edema from C5 to C7, resulting in quadriplegia. The patient developed aspiration pneumonia for which he was given vancomycin and piperacillin-tazobactam. His pneumonia progressed to ARDS, and drug-induced paralysis was attempted to reduce barotrauma and improve ventilation. Rocuronium was initiated, but the patient did not adequately respond to this treatment. Cisatracurium was then initiated, but the patient did not respond. The decision was made to discontinue the cisatracurium infusion at that time and manage the patient's ARDS without a neuromuscular blocking agent (NMBA). After several attempts to manage the patient's ARDS by adjusting ventilatory values, the patient required the reinitiation of an NMBA. The decision was made to try cisatracurium again. Cisatracurium was again unsuccessful and therefore discontinued. As a last attempt to improve oxygenation, the patient received nitric oxide and sedation with propofol. The patient died due to his complicated hospital course that included quadriplegia, ARDS, cardiac arrest, and sepsis secondary to a gastric perforation.

CONCLUSION

Inadequate paralysis was achieved with rocuronium and cisatracurium in a patient who sustained a significant trauma resulting in quadriplegia.

Pulmonary specific ancillary treatment for pediatric acute respiratory distress syndrome: proceedings from the Pediatric Acute Lung Injury Consensus Conference

OBJECTIVE

To provide an overview of the current literature on pulmonary-specific therapeutic approaches to pediatric acute respiratory distress syndrome to determine recommendations for clinical practice and/or future research.

DATA SOURCES

PubMed, EMBASE, CINAHL, SCOPUS, and the Cochrane Library were searched from inception until January 2013 using the following keywords in various combinations: ARDS, treatment, nitric oxide, heliox, steroids, surfactant, etanercept, prostaglandin therapy, inhaled beta adrenergic receptor agonists, N-acetylcysteine, ipratroprium bromide, dornase, plasminogen activators, fibrinolytics or other anticoagulants, and children. No language restrictions were applied. References from identified articles were searched for additional publications.

STUDY SELECTION

All clinical studies pertaining to pulmonary-specific therapeutic approaches to pediatric acute respiratory distress syndrome were reviewed. If clinical pediatric data were sparse or unavailable, the findings from studies of adult acute respiratory distress syndrome and animal models that might be relevant to pediatric acute respiratory distress syndrome were examined.

DATA EXTRACTION

All relevant studies were reviewed and pertinent data abstracted.

DATA SYNTHESIS

Over the course of three international meetings, the pertinent findings of the literature review were discussed by a panel of 24 experts in the field representing 21 academic institutions and 8 countries. Recommendations developed and the supporting literature were distributed to all panel members without a conflict of interest and were scored by using the Research ANd Development/University of California, Los Angeles Appropriateness method. The modified Delphi approach was used as the methodology to achieve consensus among the panel.

CONCLUSIONS

Overall, the routine use of surfactant, inhaled nitric oxide, glucocorticoids, prone positioning, endotracheal suctioning, and chest physiotherapy cannot be recommended. Inhaled nitric oxide should only be used for patients with documented pulmonary hypertension and/or right ventricular failure. Prone positioning may be considered in patients with severe pediatric acute respiratory distress syndrome. Future studies are definitely warranted to establish the role, if any, of these ancillary treatment modalities in pediatric acute respiratory distress syndrome.

NOS-2 Inhibition in Phosgene-Induced Acute Lung Injury

Phosgene exposure via an industrial or warfare release produces severe acute lung injury (ALI) with high mortality, characterized by massive pulmonary edema, disruption of epithelial tight junctions, surfactant dysfunction, and oxidative stress. There are no targeted treatments for phosgene-induced ALI. Previous studies demonstrated that nitric oxide synthase 2 (NOS-2) is upregulated in the lungs after phosgene exposure; however, the role of NOS-2 in the pathogenesis of phosgene-induced ALI remains unknown. We previously demonstrated that NOS-2 expression in lung epithelium exacerbates inhaled endotoxin-induced ALI in mice, mediated partially through downregulation of surfactant protein B (SP-B) expression. Therefore, we hypothesized that a selective NOS-2 inhibitor delivered to the lung epithelium by inhalation would mitigate phosgene-induced ALI. Inhaled phosgene produced increases in bronchoalveolar lavage fluid protein, histologic lung injury, and lung NOS-2 expression at 24 h. Administration of the selective NOS-2 inhibitor 1400 W via inhalation, but not via systemic delivery, significantly attenuated phosgene-induced ALI and preserved epithelial barrier integrity. Furthermore, aerosolized 1400 W augmented expression of SP-B and prevented downregulation of tight junction protein zonula occludens 1 (ZO-1), both critical for maintenance of normal lung physiology and barrier integrity. We also demonstrate for the first time that NOS-2-derived nitric oxide downregulates the ZO-1 expression at the transcriptional level in human lung epithelial cells, providing a novel target for ameliorating vascular leak in ALI. Our data demonstrate that lung NOS-2 plays a critical role in the development of phosgene-induced ALI and suggest that aerosolized NOS-2 inhibitors offer a novel therapeutic strategy for its treatment.

A review of inhaled nitric oxide and aerosolized epoprostenol in acute lung injury or acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are conditions associated with an estimated mortality of 40–50%. The use of inhaled vasodilators can help to improve oxygenation without hemodynamic effects. This article reviews relevant studies addressing the safety and efficacy of inhaled nitric oxide (iNO) and aerosolized epoprostenol (aEPO) in the treatment of life-threatening hypoxemia associated with ARDS and ALI. In addition, the article also provides a practicable guide to the clinical application of these therapies. Nine prospective randomized controlled trials were included for iNO reporting on changes in oxygenation or clinical outcomes. Seven reports of aEPO were examined for changes in oxygenation. Based on currently available data, the use of either iNO or aEPO is safe to use in patients with ALI or ARDS to transiently improve oxygenation. No differences have been observed in survival, ventilator-free days, or attenuation in disease severity. Further studies with consistent end points using standard delivery devices and standard modes of mechanical ventilation are needed to determine the overall benefit with iNO or aEPO.

The ability to suppress macrophage-mediated inflammation in orbital fat stem cells is controlled by miR-671-5p

Introduction

Our previous works demonstrated that systemic orbital fat-derived stem cell (OFSC) transplantation was effective in ameliorating lipopolysaccharide (LPS)-induced extensive acute lung injury (ALI) in vivo mainly through paracrine regulation of macrophage-mediated cytokine-storm. In this study, we explore the molecular mechanism(s) of OFSCs regulating macrophage activity in a cytokine-inducible fashion.

Methods

LPS (100 ng/ml)-activated macrophages were treated by conditioned medium from OFSCs (OFSCs-CM) or non-contact cultured with OFSCs for 6 hours. The potency of OFSCs on macrophage proliferation and pro-inflammation ability were determined. Expression levels of pro-inflammatory cytokines in macrophages, inducible immuno-modulatory factors in OFSCs, were investigated. Deep sequencing analysis as well as interaction between microRNA (miRNA) and genes of immuno-modulators in OFSCs induced by activated macrophages was predicted by miRTar. Transfection of miRNA inhibitor into OFSCs was performed. Real-time RT-PCR and transplantation of OFSCs into mice with LPS-induced ALI confirmed the in vitro and in vivo mechanism.

Results

The paracrine effect of OFSCs on inhibition of macrophage pro-inflammatory cytokine release was more potent than induction of macrophage G0/G1 cell cycle arrest. OFSCs-CM suppressed LPS-induced inducible nitric oxide synthetase and the pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1 alpha, and IL-1 beta expression in macrophages. Under non-contact culture, LPS-activated macrophages effectively triggered the expression of soluble immuno-modulating factors in OFSCs, i.e., IL-10, IL-1 receptor antagonist (IL-1 RA), indoleamine 2,3-dioxygenase, and soluble TNF receptor type II (sTNF RII). Under miRTar prediction, miR-671-5p was identified as a critical microRNA in regulation of multiple immune-modulating factors in OFSCs response to macrophages. The baseline level of miR-671-5p was high in OFSCs, and down-regulation of miR-671-5p upon co-culture with activated macrophages was observed. MiR-671-5p inhibitor transfection into OFSCs selectively enhanced the IL-1 RA and sTNF RII expressions. In addition, inhibition of miR-671-5p in OFSCs enhanced the anti-inflammatory ability against LPS-induced ALI.

Conclusion

The paracrine effect of OFSCs inhibits the pro-inflammatory ability and proliferation of macrophages. The immune-modulation capacity of OFSCs can be triggered by activated macrophages, and down-regulation of miR-671-5p enhances OFSC immuno-modulation ability by up-regulating IL-1 RA and sTNF RII expression.

TRIM72 is required for effective repair of alveolar epithelial cell wounding

The molecular mechanisms for lung cell repair are largely unknown. Previous studies identified tripartite motif protein 72 (TRIM72) from striated muscle and linked its function to tissue repair. In this study, we characterized TRIM72 expression in lung tissues and investigated the role of TRIM72 in repair of alveolar epithelial cells. In vivo injury of lung cells was introduced by high tidal volume ventilation, and repair-defective cells were labeled with postinjury administration of propidium iodide. Primary alveolar epithelial cells were isolated and membrane wounding and repair were labeled separately. Our results show that absence of TRIM72 increases susceptibility to deformation-induced lung injury whereas TRIM72 overexpression is protective. In vitro cell wounding assay revealed that TRIM72 protects alveolar epithelial cells through promoting repair rather than increasing resistance to injury. The repair function of TRIM72 in lung cells is further linked to caveolin 1. These data suggest an essential role for TRIM72 in repair of alveolar epithelial cells under plasma membrane stress failure.

The effect of prone positioning on mortality in patients with acute respiratory distress syndrome: a meta-analysis of randomized controlled trials

Introduction

Prone positioning (PP) has been reported to improve the survival of patients with severe acute respiratory distress syndrome (ARDS). However, it is uncertain whether the beneficial effects of PP are associated with positive end-expiratory pressure (PEEP) levels and long durations of PP. In this meta-analysis, we aimed to evaluate whether the effects of PP on mortality could be affected by PEEP level and PP duration and to identify which patients might benefit the most from PP.

Methods

Publications describing randomized controlled trials (RCTs) in which investigators have compared prone and supine ventilation were retrieved by searching the following electronic databases: PubMed/MEDLINE, the Cochrane Library, the Web of Science and Elsevier Science (inception to May 2013). Two investigators independently selected RCTs and assessed their quality. The data extracted from the RCTs were combined in a cumulative meta-analysis and analyzed using methods recommended by the Cochrane Collaboration.

Results

A total of nine RCTs with an aggregate of 2,242 patients were included. All of the studies received scores of up to three points using the methods recommended by Jadad et al. One trial did not conceal allocation. This meta-analysis revealed that, compared with supine positioning, PP decreased the 28- to 30-day mortality of ARDS patients with a ratio of partial pressure of arterial oxygen/fraction of inspired oxygen ≤100 mmHg (n = 508, risk ratio (RR) = 0.71, 95 confidence interval (CI) = 0.57 to 0.89; P = 0.003). PP was shown to reduce both 60-day mortality (n = 518, RR = 0.82, 95% CI = 0.68 to 0.99; P = 0.04) and 90-day mortality (n = 516, RR = 0.57, 95% CI = 0.43 to 0.75; P < 0.0001) in ARDS patients ventilated with PEEP ≥10 cmH₂O. Moreover, PP reduced 28- to 30-day mortality when the PP duration was >12 h/day (n = 1,067, RR = 0.73, 95% CI = 0.54 to 0.99; P = 0.04).

Conclusions

PP reduced mortality among patients with severe ARDS and patients receiving relatively high PEEP levels. Moreover, long-term PP improved the survival of ARDS patients.

Adult respiratory distress syndrome following cardiac surgery

BACKGROUND

Severe lung injury with the development of acute respiratory distress syndrome (ARDS) is a serious complication of cardiac surgery. The aim of this study was to determine the incidence, risk factors, and mortality of ARDS following cardiac surgery.

METHODS

We retrospectively analyze data in the period between January 2005 and March 2013.

RESULTS

Of 6069 patients who underwent cardiac surgery during the study period, 37 patients developed ARDS during the postoperative period. The incidence of ARDS was 0.61%, with a mortality of 40.5% (15 patients). Multivariate regression analysis identified previous cardiac surgery, complex cardiac surgery, and more than three transfusions with packed red blood cells (PRBC) were independent predictors for developing ARDS.

CONCLUSIONS

ARDS remains a serious, but very rare complication associated with significant mortality. In our study, previous cardiac surgery, complex cardiac surgery, and more than three transfusions of PRBC were independent predictors for the development of ARDS.

Mechanical ventilation enhances HMGB1 expression in an LPS-induced lung injury model

Background

Mechanical ventilation (MV) can augment inflammatory response in lipopolysaccharide (LPS) challenged lungs. High mobility group box 1 protein (HMGB1) is a pro-inflammatory mediator in ventilator-induced lung injury, but its mechanisms are not well defined. This study investigated the role of HMGB1 in lung inflammation in response to the combination of MV and LPS treatment.

Methods

Forty-eight male Sprague-Dawley rats were randomized to one of four groups: sham control; LPS treatment; mechanical ventilation; mechanical ventilation with LPS treatment. Mechanically ventilated animals received 10 ml/kg tidal volumes at a rate of 40 breaths/min for 4 h. In the HMGB1-blockade study, sixteen rats were randomly assigned to HMGB1 antibody group or control antibody group and animals were subjected to MV+LPS as described above. A549 cells were pre-incubated with different signal inhibitors before subjected to 4 h of cyclic stretch. Lung wet/dry weight (W/D) ratio, total protein and IgG concentration, number of neutrophils in bronchoalveolar lavage fluid (BALF), and lung histological changes were examined. The levels of interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α), macrophage inflammatory protein-2 (MIP-2) and HMGB1 in BALF were measured using ELISA. Real-time quantitative PCR and Western blot were used to analyze mRNA and protein expression of HMGB1. Western blot were employed to analyze the activation of IκB-α, NF-κB, JNK, ERK, and p38.

Results

MV significantly augmented LPS-induced lung injury and HMGB1 expression, which was correlated with the increase in IL-1β, IL-6 and MIP-2 levels in BALF. In vivo, intratracheally administration of HMGB1 antibody significantly attenuated pulmonary inflammatory injury. In vitro experiments showed cyclic stretch induced HMGB1 expression through signaling pathways including p38 and NF-κB.

Conclusions

The findings indicated that moderate tidal volume MV augmented LPS induced lung injury by up-regulating HMGB1. The mechanism of HMGB1-mediated lung injury is likely to be signaling through p38 and NF-κB pathways.