The effectiveness of Corticosteroids on mortality in patients with acute respiratory distress syndrome or acute lung injury: a secondary analysis

Redox-sensitive disulfide-bridged self-assembled nanoparticles of dexamethasone with high drug loading for acute lung injury therapy

Acute lung injury (ALI) arises from an excessive inflammatory response, usually progressing to acute respiratory distress syndrome (ARDS) if not promptly addressed. There is currently a limited array of effective treatments available for ALI. In this study, we developed disulfide bond-bridged prodrug self-assembled nanoparticles (referred to as DSSS NPs). These nanoparticles were consisted of Dexamethasone (Dex) and stearic acid (SA), and were designed to target and treat ALI. DSSS NPs demonstrated a substantial drug loading capacity with 37.75 % of Dex, which is much higher than conventional nanomedicines (usually < 10 %). Moreover, they exhibited the potential to specifically target injured lung tissue and inflammatory microenvironment-responsive release drugs. Consequently, DSSS NPs reduced significantly the levels of pro-inflammatory cytokines and tissue damage in mice with ALI induced by lipopolysaccharide (LPS). Overall, DSSS NPs offer a promising strategy for treatment of acute lung injury.

Dual Delivery of Tetramethylpyrazine and miR-194-5p Using Soft Mesoporous Organosilica Nanoparticles for Acute Lung Injury Therapy

Background

The respiratory system is intensely damaged by acute lung injury (ALI). The anti-inflammatory effects of tetramethylpyrazine (TMP) against ALI have been confirmed, but it exhibits a short half-life. miR-194-5p could directly target Rac1, but the internalization rate of miRNA cells was low.

Purpose

To explore the potential of the soft mesoporous organic silica nanoplatform (NPs) as carriers for delivery of TMP and miR-194-5p through the tail vein.

Methods

NPs@TMP and NPs@PEI@miR-194-5p were added to the HUVEC cell-lines, in vitro, to observe the cell uptake and cytotoxic effects. In vivo experiments were conducted by injecting fluorescently labeled NPs through the tail vein and tracking distribution. Therapeutic and toxic side-effects were analyzed systemically.

Results

In vitro study exhibited that NPs have no toxic effect on HUVECs within the experimental parameters and have excellent cellular uptake. The IVIS Spectrum Imaging System shows that NPs accumulate mainly in the lungs. NPs@TMP treatment can improved oxidative stress and inflammation levels in ALI mice and inhibited the TLR4/NLRP3/caspase 1 pathway. NPs@PEI@miR-194-5p can inhibit the Rac1/ZO-1/occludin pathway and improved endothelial cell permeability in ALI mice. The co-treatment of NPs@TMP and NPs@PEI@miR-194-5p can significantly improved the survival rates of the mice, reduced pulmonary capillary permeability and improved pathological injury in ALI mice.

Innovation

This study combined traditional Chinese medicine, bioinformatics, cellular molecular biology and nanobiomedicine to study the pathogenesis and treatment of ALI. The rate of cellular internalization was improved by changing the shape and hardness of nanoparticles. NPs@TMP and NPs@PEI@miR-194-5p combined application can significantly improve the survival condition and pathological injury of mice.

Conclusion

NPs loaded with TMP and miR-194-5p showed a greater therapeutic effect in ALI mice.

Targeted Delivery of the Pan-Inflammasome Inhibitor MM01 as an Alternative Approach to Acute Lung Injury Therapy

Acute lung injury (ALI) is a severe pulmonary disorder responsible for high percentage of mortality and morbidity in intensive care unit patients. Current treatments are ineffective, so the development of efficient and specific therapies is an unmet medical need. The activation of NLPR3 inflammasome during ALI produces the release of proinflammatory factors and pyroptosis, a proinflammatory form of cell death that contributes to lung damage spreading. Herein, it is demonstrated that modulating inflammasome activation through inhibition of ASC oligomerization by the recently described MM01 compound can be an alternative pharmacotherapy against ALI. Besides, the added efficacy of using a drug delivery nanosystem designed to target the inflamed lungs is determined. The MM01 drug is incorporated into mesoporous silica nanoparticles capped with a peptide (TNFR-MM01-MSNs) to target tumor necrosis factor receptor-1 (TNFR-1) to proinflammatory macrophages. The prepared nanoparticles can deliver the cargo in a controlled manner after the preferential uptake by proinflammatory macrophages and exhibit anti-inflammatory activity. Finally, the therapeutic effect of MM01 free or nanoparticulated to inhibit inflammatory response and lung injury is successfully demonstrated in lipopolysaccharide-mouse model of ALI. The results suggest the potential of pan-inflammasome inhibitors as candidates for ALI therapy and the use of nanoparticles for targeted lung delivery.

Near-infrared laser-irradiated upconversion nanoparticles with dexamethasone precise released for alleviating lung ischemia-reperfusion injury

Introduction: Dexamethasone (DEX), as an important enduring-effect glucocorticoid (GC), holds great promise in the field of lung ischemia-reperfusion injury (LIRI) comprehensive therapy owing to its immunomodulatory properties, such as inducing apoptosis and cell cycle distribution. However, its potent anti-inflammatory application is still restricted because of multiple internal physiologic barriers. Methods: Herein, we developed upconversion nanoparticles (UCNPs) coated with photosensitizer/capping agent/fluorescent probe-modified mesoporous silica (UCNPs@mSiO₂[DEX]-Py/β-CD/FITC, USDPFs) for precise DEX release synergistic LIRI comprehensive therapy. The UCNPs were designed by covering an inert YOF:Yb shell on the YOF:Yb, Tm core to achieve high-intensity blue and red upconversion emission upon Near-Infrared (NIR) laser irradiation. Results: Under suitable compatibility conditions, the molecular structure of photosensitizer can be damaged along with capping agent shedding, which endowed USDPFs with an outstanding capability to carry out DEX release controlling and fluorescent indicator targeting. Furthermore, the hybrid encapsulating of DEX significantly increased utilization of nano-drugs, improving the water solubility and bioavailability, which was conducive to developing the anti-inflammatory performance of USDPFs in the complex clinical environment. Discussion: The response-controlled release of DEX in the intrapulmonary microenvironment can reduce normal cell damage, which can effectively avoid the side effects of nano-drugs in anti-inflammatory application. Meanwhile, the multi-wavelength of UCNPs endowed nano-drugs with the fluorescence emission imaging capacity in an intrapulmonary microenvironment, providing precise guidance for LIRI.

The complex lipid, SPPCT-800, reduces lung damage, improves pulmonary function and decreases pro-inflammatory cytokines in the murine LPS-induced acute respiratory distress syndrome (ARDS) model

CONTEXT

Acute respiratory distress syndrome (ARDS) is a highly fatal, inflammatory condition of lungs with multiple causes. There is no adequate treatment.

OBJECTIVE

Using the murine LPS-induced ARDS model, we investigate SPPCT-800 (a complex lipid) as treatment for ARDS.

MATERIALS AND METHODS

C57B16/N mice received 50 μg of Escherichia coli O111:B4 lipopolysaccharide (LPS). SPPCT-800 was given as either: (1) 20 or 200 mg/kg dose 3 h after LPS; (2) 200 mg/kg (prophylactically) 30 min before LPS; or (3) eight 200 mg/kg treatments over 72 h. Controls received saline installations.

RESULTS

At 48 and 72 h, SpO₂ was 94% and 90% in controls compared to 97% and 94% in treated animals. Expiration times, at 24 and 48 h, were 160 and 137 msec for controls, but 139 and 107 msec with SPPCT-800. In BALF (24 h), cell counts were 4.7 × 10⁶ (controls) and 2.9 × 10⁶ (treated); protein levels were 1.5 mg (controls) and 0.4 mg (treated); and IL-6 was 942 ± 194 pg/mL (controls) versus 850 ± 212 pg/mL (treated) [at 72 h, 4664 ± 2591 pg/mL (controls) versus 276 ± 151 pg/mL (treated)]. Weight losses, at 48 and 72 h, were 20% and 18% (controls), but 14% and 8% (treated). Lung injury scores, at 24 and 72 h, were 1.4 and 3.0 (controls) and 0.3 and 2.2 (treated).

DISCUSSION AND CONCLUSIONS

SPPCT-800 was effective in reducing manifestations of ARDS. SPPCT-800 should be further investigated as therapy for ARDS, especially in longer duration or higher cumulative dose studies.

Tight Junctions, the Epithelial Barrier, and Toll-like Receptor-4 During Lung Injury

Lung epithelium is constantly exposed to the environment and is critically important for the orchestration of initial responses to infectious organisms, toxins, and allergic stimuli, and maintenance of normal gaseous exchange and pulmonary function. The integrity of lung epithelium, fluid balance, and transport of molecules is dictated by the tight junctions (TJs). The TJs are formed between adjacent cells. We have focused on the topic of the TJ structure and function in lung epithelial cells. This review includes a summary of the last twenty years of literature reports published on the disrupted TJs and epithelial barrier in various lung conditions and expression and regulation of specific TJ proteins against pathogenic stimuli. We discuss the molecular signaling and crosstalk among signaling pathways that control the TJ structure and function. The Toll-like receptor-4 (TLR4) recognizes the pathogen- and damage-associated molecular patterns released during lung injury and inflammation and coordinates cellular responses. The molecular aspects of TLR4 signaling in the context of TJs or the epithelial barrier are not fully known. We describe the current knowledge and possible networking of the TLR4-signaling with cellular and molecular mechanisms of TJs, lung epithelial barrier function, and resistance to treatment strategies.

Evolution of Acute Respiratory Distress Syndrome in Emergency and Critical Care: Therapeutic Management before and during the Pandemic Situation

Background and Objectives: Acute respiratory distress syndrome is a life-threatening lung condition that prevents enough oxygen from getting to the lungs and blood. The causes can be varied, although since the COVID-19 pandemic began there have been many cases related to this virus. The management and evolution of ARDS in emergency situations in the last 5 years was analyzed. Materials and Methods: A systematic review was carried out in the PubMed and Scopus databases. Using the descriptors Medical Subject Headings (MeSH), the search equation was: "Emergency health service AND acute respiratory distress syndrome". The search was conducted in December 2021. Quantitative primary studies on the care of patients with ARDS in an emergency setting published in the last 5 years were included. Results: In the initial management, adherence to standard treatment with continuous positive airway pressure (CPAP) is recommended. The use of extracorporeal membrane reduces the intensity of mechanical ventilation or as rescue therapy in acute respiratory distress syndrome (ARDS). The prone position in both intubated and non-intubated patients with severe ARDS is associated with a better survival of these patients, therefore, it is very useful in these moments of pandemic crisis. Lack of resources forces triage decisions about which patients are most likely to survive to start mechanical ventilation and this reflects the realities of intensive care and emergency care in a resource-limited setting. Conclusions: adequate prehospital management of ARDS and in emergency situations can improve the prognosis of patients. The therapeutic options in atypical ARDS due to COVID-19 do not seem to vary substantially from conventional ARDS.

Nanomedicine to advance the treatment of bacteria-induced acute lung injury

Bacteria-induced acute lung injury (ALI) is associated with a high mortality rate due to the lack of an effective treatment. Patients often rely on supportive care such as low tidal volume ventilation to alleviate the symptoms. Nanomedicine has recently received much attention owing to its premium benefits of delivering drugs in a sustainable and controllable manner while minimizing the potential side effects. It can effectively improve the prognosis of bacteria-induced ALI through targeted delivery of drugs, regulation of multiple inflammatory pathways, and combating antibiotic resistance. Hence, in this review, we first discuss the pathogenesis of ALI and its potential therapeutics. In particular, the state-of-the-art nanomedicines for the treatment of bacteria-induced ALI are highlighted, including their administration routes, in vivo distribution, and clearance. Furthermore, the available bacteria-induced ALI animal models are also summarized. In the end, future perspectives of nanomedicine for ALI treatment are proposed.

Cytokine storms, evolution and COVID-19

Many treatments for COVID-19 are aimed at calming a cytokine storm, a dangerous immune overreaction to the infection. Treating cytokine storms has been tried for decades in sepsis and other viral illnesses, but these treatments most often do not work. We explain why cytokine storms should be rare, and what special evolutionary circumstances can cause them to occur.

Since the identification of severe illness caused by the novel coronavirus SARS-CoV-2, the role of the host immune system in causing disease has attracted widespread attention, along with intense interest in medical interventions that target the host immune response. A wide variety of agents have been proposed to treat a cytokine storm in coronavirus disease 2019 (COVID-19), but so far, only one class of medications, corticosteroids, has proved useful. In recent decades, experimental therapies for cytokine storms have been tried and mostly failed to help patients with severe sepsis and other infections. We summarize this history in order to frame expectations for novel interventions in COVID-19 and to bring an evolutionary medicine perspective to the concept of cytokine storms and their treatment.

COVID-19, corticosteroids and public health: a reappraisal

OBJECTIVES

To assess whether regulatory guidance on the use of dexamethasone in hospitalised COVID-19 patients is applicable to the larger population of COVID-19 cases. The surge in worldwide demand for dexamethasone suggests that the guidance, although correct, has not emphasised the danger of its wider use.

STUDY DESIGN

Data from the Randomised Evaluation of COVID-19 Therapy (RECOVERY) trial and the World Health Organisation (WHO) prospective meta-analysis have been deconstructed and analysed.

METHODS

To provide context, relevant publications were identified in PubMed using the following keywords: COVID-19, RECOVERY trial, WHO meta-analysis, variants, immunity, public health.

RESULTS

The WHO guidance 'Corticosteroids for COVID-19' was based on their prospective meta-analysis. This meta-analysis was weighted by data from the RECOVERY trial.

CONCLUSIONS

In terms of COVID-19, dexamethasone has value in a narrow indication, namely, in hospitalised patients requiring respiratory support. The media blitz likely resulted in the wider use of dexamethasone in outpatients and as a preventive medication. This is reflected in the surge in worldwide demand for dexamethasone. We ask whether the use of steroids, beyond regulatory indications, may be responsible for the recent increase in mortality and especially the emergence of mucormycosis? From the public health standpoint, the current guidance for use of dexamethasone in COVID-19 could benefit from clarification and the addition of a cautionary note.

The Role of Glucocorticoids in the Treatment of ARDS: A Multicenter Retrospective Study Based on the eICU Collaborative Research Database

Background: Acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure in patients in intensive care unit (ICU). The therapeutic value of glucocorticoids (GCs) in the prognosis of ARDS remains controversial. The aim of this research is studying the impacts of GCs treatment on ARDS patients in ICU. Methods: We retrospectively studied 2,167 ARDS patients whose data were collected from the public eICU Collaborative Research Database, among which 254 patients who received glucocorticoid (GCs) treatment were 1:1 matched by propensity matching analysis (PSM). The primary outcome was ICU mortality. Every oxygenation index (PaO2/FiO2) measurement before death or ICU discharge was recorded. A joint model (JM) which combined longitudinal sub-model (mixed-effect model) and time-to-event sub-model (Cox regression model) by trajectory functions of PaO2/FiO2 was conducted to determine the effects of GCs treatment on both ICU mortality and PaO2/FiO2 level and further PaO2/FiO2's effect on event status. The marginal structural cox model (MSCM) adjusted the overall PaO2/FiO2 of patients to further validate the results. Results: The result of the survival sub-model showed that GCs treatment was significantly associated with reduced ICU mortality in ARDS patients [HR (95% CI) = 0.642 (0.453, 0.912)], demonstrating that GCs treatment was a protective factor of ICU mortality. In the longitudinal sub-model, GCs treatment was not correlated to the PaO2/FiO2. After adjusted by the JM, the HR of GCs treatment was 0.602 while GCs was still not significantly related to PaO2/FiO2 level. The JM-induced association showed that higher PaO2/FiO2 was a significant protective factor of mortality in ARDS patients and the HR was 0.991 which demonstrated that one level increase of PaO2/FiO2 level decreased 0.9% risk of ICU mortality. MSCM results also show that GCs can improve the prognosis of patients. Conclusion: Rational use of GCs can reduce the ICU mortality of ARDS patients in ICU. In addition to the use of GCs treatment, clinicians should also focus on the shifting trend of PaO2/FiO2 level to provide better conditions for patients' survival.

Glucocorticoids for acute respiratory distress syndrome: A systematic review with meta-analysis and trial sequential analysis

BACKGROUND

Glucocorticoids are some of the most commonly used drugs for patients with acute respiratory distress syndrome (ARDS). However, the curative effect and side effects of glucocorticoids in treating patients with ARDS remain controversial.

METHODS

Three databases were searched until 2 July 2020, and randomized controlled trials (RCTs) that compared glucocorticoids versus other therapies in the treatment of ARDS were included in this meta-analysis. Trial sequential analysis (TSA) was conducted.

RESULTS

A total of 14 RCTs with 1362 ARDS patients were assessed. Overall, no statistically significant effect was found on mortality between the glucocorticoid group and the control group of ARDS patients. In the subgroup analysis, no benefit of glucocorticoids for ARDS on mortality was found in trials stratified according to low versus high risk of bias or with vs. without a loading dose. As for the dose and length of therapy, no statistically significant effect was found on mortality with high-dose, short-course glucocorticoid therapy. However, lower-dose and longer-course therapy with glucocorticoids was found to decrease the mortality of ARDS patients (lower dose: RR = 0.69, 95% CI = 0.51-0.93, P = .02; longer-course therapy: RR = 0.60, 95% CI = 0.37-0.99, P = .04). The TSA showed that more trials are needed to confirm the results.

CONCLUSIONS

Longer- and lower-dose glucocorticoid treatment may improve the prognosis of ARDS patients, but RCTs with higher quality and larger sample sizes are needed to further clarify the clinical effects of glucocorticoids on ARDS.

Circulating Exosomes From Lipopolysaccharide-Induced Ards Mice Trigger Endoplasmic Reticulum Stress in Lung Tissue

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a critical clinical syndrome with high mortality rate, and few effective therapies have been found in the past 50 years, indicating that the pathogenesis of ARDS remains unclear. Exosomes, a novel cross-communication mechanism, are involved in critical diseases. However, the role of circulating exosomes in the development of ARDS remains poorly understood.

METHODS

In the present study, naive mice were treated with circulating exosomes from lipopolysaccharide (LPS)-induced ARDS mice or exosome-depleted serum. Histological lung damage, bronchoalveolar lavage fluid (BALF), and endoplasmic reticulum (ER) stress were measured.

RESULTS

Increased tumor necrosis factor (TNF)-α, interleukin (IL)-6, total cell counts, polymorphonuclear (PMN) leukocyte proportions and myeloperoxidase (MPO) activity in BALF, and increased wet/dry weight ratios and protein concentrations in BALF were found in mice after exosome injection but not in mice treated with exosome-depleted serum. Furthermore, western blot analysis showed that circulating exosomes from ARDS mice upregulated glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP) expression and downregulated β-Catenin and VE-cadherin expression in lung tissues.

CONCLUSIONS

Collectively, these data demonstrate that circulating exosomes from LPS-induced ARDS mice trigger ER stress in lung tissue, facilitating the development of ARDS, at least partly by promoting endothelial dysfunction.

Small Immunomodulatory Molecules as Potential Therapeutics in Experimental Murine Models of Acute Lung Injury (ALI)/Acute Respiratory Distress Syndrome (ARDS)

Background: Acute lung injury (ALI) or its most advanced form, acute respiratory distress syndrome (ARDS) is a severe inflammatory pulmonary process triggered by a variety of insults including sepsis, viral or bacterial pneumonia, and mechanical ventilator-induced trauma. Currently, there are no effective therapies available for ARDS. We have recently reported that a novel small molecule AVR-25 derived from chitin molecule (a long-chain polymer of N-acetylglucosamine) showed anti-inflammatory effects in the lungs. The goal of this study was to determine the efficacy of two chitin-derived compounds, AVR-25 and AVR-48, in multiple mouse models of ALI/ARDS. We further determined the safety and pharmacokinetic (PK) profile of the lead compound AVR-48 in rats. Methods: ALI in mice was induced by intratracheal instillation of a single dose of lipopolysaccharide (LPS; 100 µg) for 24 h or exposed to hyperoxia (100% oxygen) for 48 h or undergoing cecal ligation and puncture (CLP) procedure and observation for 10 days. Results: Both chitin derivatives, AVR-25 and AVR-48, showed decreased neutrophil recruitment and reduced inflammation in the lungs of ALI mice. Further, AVR-25 and AVR-48 mediated diminished lung inflammation was associated with reduced expression of lung adhesion molecules with improvement in pulmonary endothelial barrier function, pulmonary edema, and lung injury. Consistent with these results, CLP-induced sepsis mice treated with AVR-48 showed a significant increase in survival of the mice (80%) and improved lung histopathology in the treated CLP group. AVR-48, the lead chitin derivative compound, demonstrated a good safety profile. Conclusion: Both AVR-25 and AVR-48 demonstrate the potential to be developed as therapeutic agents to treat ALI/ARDS.

Anti-Inflammatory Effects of Sosiho-Tang, a Traditional Herbal Formula, on Acute Lung Injury in LPS-Sensitized Mice and -Raw 264.7 Cells

Acute lung injury (ALI) is a series of syndromes with persistent inflammation and abnormally increased vascular permeability. Sosiho-tang (SSHT), a traditional herbal formula consisting of a mixture of seven herbs, has been used to treat allergic reactions and chronic hepatitis disease in East Asia. In this study, we determined whether SSHT has an inhibitory effect against lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in mice. 0.05, 0.55, and 5.55 mg/kg of SSHT were orally administered to C57BL/6J mice for 7 days prior to the administration of LPS. After 2 h of LPS sensitization, lung tissues were collected to confirm the lung histology and ALI-related inflammatory factors. SSHT ameliorated the LPS-induced alveolar hemorrhage, alveolar wall thickening, and the shrinkage of the alveolar spaces in the ALI mice model. Proinflammatory cytokines including IL-6, TNF-α, and IFN-γ in the lung tissue were significantly regulated in the SSHT-treated groups compared to the LPS only-treated group. Also, increases of IL-6 and TNF-α and decrease of IFN-γ expressions were dose-dependently modulated by SSHT treatment in LPS-induced raw 264.7 cells. Additionally, the translocation of NF-κB into nucleus and phosphorylation of mitogen-activated protein (MAP) kinase were significantly attenuated by the treatment of SSHT in LPS-sensitized ALI mice. SSHT showed anti-inflammatory activities by inhibiting proinflammatory cytokines and NF-κB signaling in LPS-induced ALI. This study demonstrates that SSHT has preventive effects on LPS-induced ALI by regulating inflammatory responses as an alternative for treating lung diseases.

Analytics with artificial intelligence to advance the treatment of acute respiratory distress syndrome

Artificial intelligence (AI) has found its way into clinical studies in the era of big data. Acute respiratory distress syndrome (ARDS) or acute lung injury (ALI) is a clinical syndrome that encompasses a heterogeneous population. Management of such heterogeneous patient population is a big challenge for clinicians. With accumulating ALI datasets being publicly available, more knowledge could be discovered with sophisticated analytics. We reviewed literatures with big data analytics to understand the role of AI for improving the caring of patients with ALI/ARDS. Many studies have utilized the electronic medical records (EMR) data for the identification and prognostication of ARDS patients. As increasing number of ARDS clinical trials data is open to public, secondary analysis on these combined datasets provide a powerful way of finding solution to clinical questions with a new perspective. AI techniques such as Classification and Regression Tree (CART) and artificial neural networks (ANN) have also been successfully used in the investigation of ARDS problems. Individualized treatment of ARDS could be implemented with a support from AI as we are now able to classify ARDS into many subphenotypes by unsupervised machine learning algorithms. Interestingly, these subphenotypes show different responses to a certain intervention. However, current analytics involving ARDS have not fully incorporated information from omics such as transcriptome, proteomics, daily activities and environmental conditions. AI technology is assisting us to interpret complex data of ARDS patients and enable us to further improve the management of ARDS patients in future with individual treatment plans.

MicroRNA‑17 contributes to the suppression of the inflammatory response in lipopolysaccharide‑induced acute lung injury in mice via targeting the toll‑like receptor 4/nuclear factor‑κB pathway

Acute lung injury (ALI) is a common lung disease with a high mortality rate, which is characterized by an excessive uncontrolled inflammatory response. MicroRNA (miR)-17 has previously emerged as a novel regulatory molecule of inflammatory response in various complex diseases; however, the anti-inflammatory action and associated molecular mechanisms of miR-17 in ALI have not been fully elucidated. The aim of the present study was to investigate the role of miR-17 in the inflammatory response in ALI and to elucidate the potential underlying mechanism. Using a lipopolysaccharide (LPS)-induced ALI mouse model, it was observed that miR-17 was significantly downregulated in lung tissues compared with the control group. In this model, ectopic expression of miR-17 attenuated lung pathological damage, reduced lung wet/dry ratio and lung permeability, and increased survival rate in ALI mice. In addition, agomiR-17 injection significantly suppressed LPS-induced inflammation, as evidenced by a reduction in the activity of myeloperoxidase and the production of interleukin (IL)-6, IL-1β and tumor necrosis factor-α in lung tissues. Of note, toll-like receptor (TLR) 4, an upstream regulator of the nuclear factor (NF)-κB inflammatory signaling pathway, was directly targeted by miR-17, and its translation was suppressed by miR-17 in vitro and in vivo. Using an LPS-induced RAW264.1 macrophage injury model, it was observed that miR-17 overexpression suppressed the pro-inflammatory effect of LPS, while these inhibitory effects were markedly abrogated by TLR4 overexpression. In addition, TLR4 knockdown by si-TLR4 mimicked the effects of miR-17 overexpression on LPS-induced cytokine secretion in the in vitro model. Further experiments revealed that miR-17 significantly reduced the expression of key proteins in the NF-κB pathway, including IKKβ, p-IκBα and nuclear p-p65, and suppressed the NF-κB activity in ALI mice. Collectively, these results indicated that miR-17 protected mice against LPS-induced lung injury via inhibiting inflammation by targeting the TLR4/NF-κB pathway; therefore, miR-17 may serve as a potential therapeutic target for ALI.

Mediation Analysis Reveals Potential Biological Mechanism of Ascites Influencing Recurrence in Patients with Epithelial Ovarian Cancer

Objective

Ascites, an accumulation of peritoneal fluid, is associated with poor prognosis of certain cancers. The potential mechanism that ascites worsens prognosis has not been well understood. Lipids have been reported to correlate with the prognosis of patients with epithelial ovarian cancer (EOC). Therefore, we aimed here to investigate whether lipids mediate the effect of ascites on the recurrence of EOC.

Methods

We collected the demographic and pathological data of 437 previously untreated patients with EOC to investigate the influence of ascites on recurrence. To identify the mechanism that mediates the potential influence of ascites on recurrence, we used ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS) to determine the plasma lipid profiles of 53 patients with EOC. We used mediation analysis to evaluate if lipids mediated the effects of ascites on the recurrence of EOC.

Results

Patients with ascites had a poorer prognosis, which was associated with higher levels of carbohydrate antigen-CA125 (CA125) and FIGO stage. We identified six different lipid metabolites that were associated with ascites and recurrence. Mediation analysis revealed that the lipids LysoPC(P-15:0), PC(P-34:4), and PC(38:6) may mediate the effects of ascites on recurrence.

Conclusion

Our findings suggest that LysoPC(P-15:0), PC(P-34:4), and PC(38:6) mediate the effect of ascites on the prognosis of patients with EOC. We believe therefore that it is reasonable to consider metabolic interventions targeting the metabolism of LysoPC(P-15:0), PC(P-34:4), and PC(38:6) as a palliative treatment for patients with EOC with ascites. Further studies of more patients will be required to validate our findings.

Steroids in pediatric acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a complex entity with high potential for harm and healthcare resource utilization. Despite multiple clinical advances in its ventilatory management, ARDS continues to be one of the most challenging disease processes for intensivists. It continues to lack a direct, proven and desperately needed effective therapeutic intervention. Given their biologic rationale, corticosteroids have been widely used by clinicians and considered useful by many in the management of ARDS since its first description. Adult data is abundant, yet contradictory. Controversy remains regarding the routine use of corticosteroids in ARDS. Therefore, widespread evidence-based recommendations for this heterogeneous disease process have not been made. In this article, our aim was to provide a summary of available evidence for the role of steroids in the treatment of ARDS, while giving special focus on pediatric ARDS (PARDS).

Prediction model for patients with acute respiratory distress syndrome: use of a genetic algorithm to develop a neural network model

BACKGROUND

Acute respiratory distress syndrome (ARDS) is associated with significantly increased risk of death, and early risk stratification may help to choose the appropriate treatment. The study aimed to develop a neural network model by using a genetic algorithm (GA) for the prediction of mortality in patients with ARDS.

METHODS

This was a secondary analysis of two multicenter randomized controlled trials conducted in forty-four hospitals that are members of the National Heart, Lung, and Blood Institute, founded to create an acute respiratory distress syndrome Clinical Trials Network. Model training and validation were performed using the SAILS and OMEGA studies, respectively. A GA was employed to screen variables in order to predict 90-day mortality, and a neural network model was trained for the prediction. This machine learning model was compared to the logistic regression model and APACHE III score in the validation cohort.

RESULTS

A total number of 1,071 ARDS patients were included for analysis. The GA search identified seven important variables, which were age, AIDS, leukemia, metastatic tumor, hepatic failure, lowest albumin, and FiO2. A representative neural network model was constructed using the forward selection procedure. The area under the curve (AUC) of the neural network model evaluated with the validation cohort was 0.821 (95% CI [0.753-0.888]), which was greater than the APACHE III score (0.665; 95% CI [0.590-0.739]; p = 0.002 by Delong's test) and logistic regression model, albeit not statistically significant (0.743; 95% CI [0.669-0.817], p = 0.130 by Delong's test).

CONCLUSIONS

The study developed a neural network model using a GA, which outperformed conventional scoring systems for the prediction of mortality in ARDS patients.

Circ 0001434 RNA reduces inflammation in acute lung injury model through Wnt/β-catenin and NF-κB by miR-625-5p

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are common and complicated inflammatory lung diseases. Circ RNAs have emerged as a novel class of gene regulatory molecules that play vital roles in multiple complex diseases, including ALI. In this study, we aimed to identify potential regulators of Circ 0001434 on acute lung injury (ALI) and to explore their roles in lipopolysaccharide (LPS)-induced ALI. In a mouse ALI model, Circ 0001434 expression was effectively down-regulated, compared with the control group. Up-regulation of Circ 0001434 effectively decreased the inflammation of ALI in an in vitro model. Down-regulation of Circ 0001434 effectively promoted inflammation in ALI in an in vitro model. Over-expression of Circ 0001434 induced Wnt and β-catenin protein expression, and suppressed NF-κB p65 protein expression in the ALI in vitro model by miR-625-5p. Down-regulation of Circ 0001434 significantly suppressed Wnt and β-catenin, and induced NF-κB p65 protein expression in the ALI in vitro model by miR-625-5p. Wnt reduced the function of Circ 0001434 on inflammation in ALI in an in vitro model. The inhibition of miR-625-5p reversed the function of anti-Circ 0001434 on inflammation in ALI vitro model. Taken together, Circ 0001434 mediates ALI-induced lung inflammation through Wnt/β-catenin and NF-κB activation by miR-625-5p.

Early corticosteroid treatment for postoperative acute lung injury after lung cancer surgery

Background:

Acute lung injury (ALI) is the most serious pulmonary complication after lung resection. Although the beneficial effects of low-dose corticosteroids have been demonstrated in patients with postoperative ALI, there are limited data on optimal corticosteroid treatment.

Methods:

We retrospectively analyzed 58 patients who were diagnosed with ALI among 7593 patients who underwent lung cancer surgery between January 2009 and December 2016.

Results:

Of the 58 patients, 42 (72%) received corticosteroid treatment within 72 h (early treatment group) and 16 (28%) received corticosteroid treatment more than 72 h after ALI occurred (late treatment group). The early treatment group demonstrated a higher response to corticosteroid treatment compared with the late treatment group (95% versus 69%, respectively, p = 0.014), had an improved lung injury score (86% versus 63%, p = 0.072), and were more likely to be successfully weaned from the ventilator within 7 days (57% versus 39%, p = 0.332). During corticosteroid treatment, the early treatment group had a lower rate of delirium (24% versus 63%, p = 0.012) compared with the late treatment group. No significant differences in length of stay (30 versus 37 days, p = 0.254) or in-hospital mortality (43% versus 38%, p = 0.773) were observed; however, the early treatment group tended to have a higher rate of successful weaning than the late treatment group (p = 0.098, log-rank test).

Conclusions:

Early initiation of corticosteroid treatment improved lung injury and promoted ventilator weaning in patients with ALI following lung resection for lung cancer.

TLR4/NF-κB signaling pathway gene single nucleotide polymorphisms alter gene expression levels and affect ARDS occurrence and prognosis outcomes

BACKGROUND

To study the occurrence and prognosis of acute respiratory distress syndrome (ARDS) using single nucleotide polymorphisms (SNPs) of TNF-α rs1800629, IL-6 rs1800796, and MyD88 rs7744 loci in the TLR4/NF-κB pathway.

METHODS

Genotypes were analyzed for TNF-α rs1800629, IL-6 rs1800796, and MyD88 rs7744 loci. Plasma TNF-α and IL-6 levels and MyD88 mRNA expression in peripheral blood mononuclear cells (PBMCs) of 300 ARDS patients and 300 non-ARDS patients (control group) were examined. The patients were followed up for 60 days, and the prognosis outcome was recorded.

RESULTS

The TNF-α rs1800629 locus A allele and the IL-6 rs1800796 locus G allele were found to be risk factors for ARDS (adjusted OR = 1.452, 95% CI: 1.211-1.689, P < .001 and adjusted OR = 1.205, 95% CI: 1.058-1.358, P = .005, respectively). The G allele at MyD88 rs7744 locus was a protective factor against ARDS (adjusted OR = 0.748, 95% CI: 0.631-0.876, P < .001). Compared with the other groups, homozygotes for TNF-α rs1800629, IL-6 rs1800796, and MyD88 rs7744 loci had higher expression levels, of which homozygotes for TNF-α rs1800629 and IL-6 rs1800796 loci had lower 60-day survival rates, while MyD88 rs7744 locus homozygotes had a higher 60-day survival rate.

CONCLUSION

The effect of TNF-α rs1800629, IL-6 rs1800796, and MyD88 rs7744 SNPs on gene expression level is a likely cause of ARDS occurrence and poor prognosis.

Platelet-derived growth factor-D expression mediates the effect of differentiated degree on prognosis in epithelial ovarian cancer

Platelet-derived growth factor-D (PDGF-D) can enhance invasion and metastasis in several human malignancies. Although several studies have been performed to investigate the association between clinicopathological characteristics and prognosis in epithelial ovarian cancer (EOC), the mediation effect of PDGF-D on above-mentioned association have been seldom assessed. In this study, we detected the PDGF-D expression from the tissues of patients with EOC and further collected clinicopathological characteristics and prognostic information to identify whether PDGF-D mediated the effect of differentiated degree on prognosis in patients with EOC. A total of 190 paraffin-embedded tissue samples from patients with EOC between July 2005 and December 2010 were collected. We performed a Kaplan-Meier analysis for the association between differentiated degree and prognosis followed by a causal mediation analysis. The analysis results indicated that differentiated degree was associated with prognosis and PDGF-D mediated the effect of differentiated degree on prognosis in patients with EOC, which might be a potential target for ovarian cancer treatment.

Dexmedetomidine Ameliorates Post-CPB Lung Injury in Rats by Activating the PI3K/Akt Pathway

Purpose: To investigate the protective effects of dexmedetomidine (Dex) on post cardiopulmonary bypass (CPB) lung injury in rats and to explore the possibility of underlying mechanisms involving phosphatidylinositol 3-kinase (PI3K)/Akt. Materials and Methods: Forty healthy male Sprague-Dawley rats were randomly divided into five groups (n = 8 for each). A left lung ischemia-reperfusion injury model of CPB was established in all five groups. Rats were given saline, dexmedetomidine (Dex), dimethyl sulfoxide (DMSO), wortmannin (Wtm), and Dex plus Wtm during the CPB process, in Group Saline, Dex, DMSO, Wtm, and Dex + Wtm, respectively. Mean arterial pressure, oxygenation index (OI), and respiratory index (RI) were measured at the following three timepoints: before CPB (T₁), at the onset of opening of the left hilus pulmonis (T₂), and at the end of the CPB process (T₃). At T_3, hematoxylin and eosin (H&E) staining was conducted to evaluate pathology of lung injury. The rate of lung tissue apoptosis was determined by flow-cytometry. The expression of Akt, p-Akt, caspase-3, and caspase-9 was assessed by Western blot. Results: Dex treatment during CPB protected rat lungs from post-CPB lung injury, manifested by improved lung function, mitigated pathological damage, and reduced lung tissue apoptosis. The expression and phosphorylation of Akt was significantly enhanced by Dex treatment compared to the saline/DMSO-treated group. Wtm, a recognized PI3K inhibitor, abolished the protective effect of Dex. The levels of caspase-3 and caspase-9 were also significantly elevated in the Wtm-treated group. Conclusions: Dex reduces post-CPB lung injury in rats, at least partially, by activating the PI3K/Akt pathway and inhibiting lung tissue apoptosis.

Identification of subclasses of sepsis that showed different clinical outcomes and responses to amount of fluid resuscitation: a latent profile analysis

BACKGROUND AND OBJECTIVE

Sepsis is a heterogeneous disease and identification of its subclasses may facilitate and optimize clinical management. This study aimed to identify subclasses of sepsis and its responses to different amounts of fluid resuscitation.

METHODS

This was a retrospective study conducted in an intensive care unit at a large tertiary care hospital. The patients fulfilling the diagnostic criteria of sepsis from June 1, 2001 to October 31, 2012 were included. Clinical and laboratory variables were used to perform the latent profile analysis (LPA). A multivariable logistic regression model was used to explore the independent association of fluid input and mortality outcome.

RESULTS

In total, 14,993 patients were included in the study. The LPA identified four subclasses of sepsis: profile 1 was characterized by the lowest mortality rate and having the largest proportion and was considered the baseline type; profile 2 was characterized by respiratory dysfunction; profile 3 was characterized by multiple organ dysfunction (kidney, coagulation, liver, and shock), and profile 4 was characterized by neurological dysfunction. Profile 3 showed the highest mortality rate (45.4%), followed by profile 4 (27.4%), 2 (18.2%), and 1 (16.9%). Overall, the amount of fluid needed for resuscitation was the largest on day 1 (median 5115 mL, interquartile range (IQR) 2662 to 8800 mL) and decreased rapidly on day 2 (median 2140 mL, IQR 900 to 3872 mL). Higher cumulative fluid input in the first 48 h was associated with reduced risk of hospital mortality for profile 3 (odds ratio (OR) 0.89, 95% CI 0.83 to 0.95 for each 1000 mL increase in fluid input) and with increased risk of death for profile 4 (OR 1.20, 95% CI 1.11 to 1.30).

CONCLUSION

The study identified four subphenotypes of sepsis, which showed different mortality outcomes and responses to fluid resuscitation. Prospective trials are needed to validate our findings.

Two indole-2-carboxamide derivatives attenuate lipopolysaccharide-induced acute lung injury by inhibiting inflammatory response

Acute lung injury (ALI) is the leading cause of mortality in the intensive care unit. Currently, there is no effective pharmacological treatment for ALI. In our previous study, we reported that Lg25 and Lg26, two indole-2-carboxamide derivatives, inhibited the lipopolysaccharide (LPS)-induced inflammatory cytokines in vitro and attenuated LPS-induced sepsis in vivo. In the present study, we confirmed data from previous studies that LPS significantly induced pulmonary edema and pathological changes in lung tissue, increased protein concentration and number of inflammatory cells in bronchoalveolar lavage fluids (BALF), and increased inflammatory cytokine TNF-α expression in serum and BALF, pro-inflammatory genes expression, and macrophages infiltration in lung tissue. However, pretreatment with Lg25 and Lg26 significantly attenuated the LPS-induced changes in mice. Taken together, these data indicate that the newly discovered indole-2-carboxamide derivatives could be particularly useful in the treatment of inflammatory diseases such as ALI.

Upregulation of miRNA-140-5p inhibits inflammatory cytokines in acute lung injury through the MyD88/NF-κB signaling pathway by targeting TLR4

The present study was designed to determine the effect of miR-140-5p on acute lung injury (ALI) and the associated inflammation induced. As a result, miR-140-5p expression in mice with ALI was suppressed when compared with the normal group. Downregulation of miR-140-5p increased the levels of inflammatory factors induced by ALI [including tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and myeloperoxidase] in an in vitro model of human lung A549 cells. Downregulation of miR-140-5p also induced the protein expression of Toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88) and nuclear factor (NF)-κB in an in vitro model. Overexpression of miR-140-5p reduced the levels of inflammation in the in vitro model of ALI via the suppression of the TLR4/MyD88/NF-κB signaling pathway. The inhibition of TLR4 using a TLR4 inhibitor reduced the proinflammation effects of anti-miR-140-5p in the in vitro model of ALI. The NF-κB inhibitor also inhibited the proinflammation effects of anti-miR-140-5p in the in vitro model of ALI. Overall, the results of the present study indicated that miR-140-5p inhibited ALI-induced inflammation via the TLR4/MyD88/NF-κB signaling pathway.

Regulation of the NLRP3 inflammasome and macrophage pyroptosis by the p38 MAPK signaling pathway in a mouse model of acute lung injury

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) is characterized by uncontrolled progressive lung inflammation. Macrophages serve a key role in the pathogenesis of ALI/ARDS. Macrophage pyroptosis is a process of cell death releasing the proinflammatory cytokines interleukin (IL)‑1β and IL‑18. It was hypothesized that macrophage pyroptosis may partially account for the uncontrolled lung inflammation of ALI/ARDS. In the present study, greater macrophage pyroptosis in lipopolysaccharide (LPS)‑treated macrophages and the ALI/ARDS mouse model was observed. The expression of nucleotide‑binding domain, leucine‑rich‑containing family, pyrin domain‑containing (NLRP)3 and IL‑1β and cleavage of caspase‑1 were significantly elevated following LPS treatment accompanied by greater activation of p38 mitogen‑activated protein kinase (MAPK) signaling in vitro and in vivo. However, blocking p38 MAPK signaling through the inhibitor SB203580 significantly suppressed the acute lung injury and excessive lung inflammation in vivo, consistent with the reduced expression of the NLRP3 inflammasome and IL‑1β and cleavage of caspase‑1. Pretreatment of the rat NR8383 macrophage cell line with SB203580 significantly decreased the population of caspase‑1+PI+ pyroptotic cells and expression of NLRP3/IL‑1β. However, a larger population of Annexin V+PI‑ apoptotic cells was observed following blocking of the p38 MAPK signaling pathway. The results indicated that blockage of p38 MAPK signaling pathway skewed macrophage cell death from proinflammatory pyroptosis towards non‑inflammatory apoptosis. These effects may contribute to attenuated acute lung injury and excessive inflammation in the SB203580‑treated mice. The results may provide a novel therapeutic strategy for the treatment of uncontrolled lung inflammation in patients with ALI/ARDS.

Aerobic Exercise Protects from Pseudomonas aeruginosa-Induced Pneumonia in Elderly Mice

BACKGROUND

Pseudomonas aeruginosa (PS) infection results in severe morbidity and mortality, especially in immune-deficient populations. Aerobic exercise (AE) modulates the immune system, but its effects on the outcomes of pulmonary PS infection in elderly mice are unknown.

METHODS

BALB/c mice (24 weeks old) were randomized to sedentary, exercise (EX), PS, and PS + EX groups for the acute experimental setting, and PS and PS + EX groups for the chronic setting. Low-intensity AE was performed for 5 weeks, 60 min/day; 24 h after the final AE session, mice were inoculated with 5 × 104 colony-forming units (CFU) of PS, and 24 h and 14 days after PS inoculation, mice were studied.

RESULTS

AE inhibited PS colonization (p < 0.001) and lung inflammation (total cells, neutrophils, lymphocytes [p < 0.01] in bronchoalveolar lavage [BAL]), with significant differences in BAL levels of IL-1β (p < 0.001), IL-6 (p < 0.01), CXCL1 (p < 0.001), and TNF-α (p < 0.001), as well as parenchymal neutrophils (p < 0.001). AE increased BAL levels of IL-10 and parenchymal (p < 0.001) and epithelial (p < 0.001) IL-10 expression, while epithelial (p < 0.001) and parenchymal (p < 0.001) NF-κB expression was decreased. AE diminished pulmonary lipid peroxidation (p < 0.001) and increased glutathione peroxidase (p < 0.01). Pre-incubation of BEAS-2B with IL-10 inhibited PS-induced epithelial cell expression of TNF-α (p < 0.05), CD40 (p < 0.01), and dichlorodihydrofluorescein diacetate (p < 0.05).

CONCLUSIONS

AE inhibits PS-induced lung inflammation and bacterial colonization in elderly mice, involving IL-10/NF-κB, and redox signaling.

Pulmonary lymphangioleimyomatosis and systemic lupus erythematosus in a menopausal woman

Background

Pulmonary lymphangioleimyomatosis (PLAM) is a rare disease involving lung. PLAM primarily affects young women, a characteristic it shares with systemic lupus erythematosus (SLE). Estrogen has long been assumed to play an important role both in PLAM and SLE. We report a menopausal woman, who was found to have PLAM 1 year after she was diagnosed with SLE. Her chest radiograph was normal in the early phase of SLE.

Case presentation

A 52-year-old Chinese woman was referred to our hospital in August 2014 because of swelling in both legs. She also reported a malar rash and intermittent generalized arthralgia. Laboratory examination showed leukopenia. Her serum albumin level was 23 g/L; 24-h urinary protein excretion was 5.3 g. She tested positive for anti-Smith (Sm) antibody and anti-SS-A antibody. Renal biopsy indicated Class V + IV(G)-A lupus nephritis (LN). The condition of SLE and LN improved on a regime of tapering prednisolone and intermittent intravenous cyclophosphamide therapy until 1 year later when she developed exertional dyspnea accompanied with frequent cough. Thoracic computed tomography revealed numerous well-defined cysts and the diagnosis of PLAM was confirmed by lung biopsy. In the follow-up period, the patient continued to be on prednisolone and mycophenolate mofetil for the treatment of SLE, but only agreed to receive symptomatic treatment for PLAM. One year after the diagnosis of PLAM, during which time the SLE was stable, she died of respiratory failure and cor pulmonale.

Conclusion

We report a patient with coexisting SLE and PLAM, who was treated with immunosuppressive therapy. SLE was stable but PLAM was not improved. Although the coexistence of SLE and PLAM might be a coincidence, the occurrence of these two diseases in a menopausal woman may warrant further mechanistic exploration.

Endogenous PGI2 signaling through IP inhibits neutrophilic lung inflammation in LPS-induced acute lung injury mice model

Endogenous prostaglandin I₂ (PGI₂) has inhibitory effects on immune responses against pathogens or allergens; however, the immunomodulatory activity of endogenous PGI₂ signaling in endotoxin-induced inflammation is unknown. To test the hypothesis that endogenous PGI₂ down-regulates endotoxin-induced lung inflammation, C57BL/6 wild type (WT) and PGI₂ receptor (IP) KO mice were challenged intranasally with LPS. Urine 6-keto-PGF_1α, a stable metabolite of PGI_2, was significantly increased following the LPS-challenge, suggesting that endogenous PGI₂ signaling modulates the host response to LPS-challenge. IPKO mice had a significant increase in neutrophils in the BAL fluid as well as increased proteins of KC, LIX, and TNF-α in lung homogenates compared with WT mice. In contrast, IL-10 was decreased in LPS-challenged IPKO mice compared with WT mice. The PGI₂ analog cicaprost significantly decreased LPS-induced KC, and TNF-α, but increased IL-10 and AREG in bone marrow-derived dendritic cells (BMDCs) and bone marrow-derived macrophages (BMMs) compared with vehicle-treatment. These results indicated that endogenous PGI₂ signaling attenuated neutrophilic lung inflammation through the reduced inflammatory cytokine and chemokine and enhanced IL-10.

Identification of three classes of acute respiratory distress syndrome using latent class analysis

Acute respiratory distress syndrome (ARDS) is a highly heterogeneous syndrome that can exhibit significant differences in the underlying causes, leading to different responses to treatment. It is required to identify subtypes of ARDS to guideline clinical treatment and trial design. The study aimed to identify subtypes of ARDS using latent class analysis (LCA). The study was a secondary analysis of the EDEN study, which was a randomized, controlled, multicenter trial conducted from January 2, 2008 to April 12, 2011. The primary study endpoint was death through 90-day follow up. LCA was performed incorporating variables on day 0 before randomization. The number of classes was chosen by a bootstrapped likelihood ratio test, Bayesian information criterion and the number of patients in each class. A total of 943 patients were enrolled in the study, including 219 (23.2%) non-survivors and 724 (76.8%) survivors. The LCA identified three classes of ARDS. Class 1 (hemodynamically unstable type) had significantly higher mortality rate (p = 0.003) than class 2 (intermediate type) and 3 (stable type) through 90 days follow up. There was significant interaction between cumulative fluid balance and the class (p = 0.02). While more fluid balance was beneficial for class 1, it was harmful for class 2 and 3. In conclusion, the study identified three classes of ARDS, which showed different clinical presentations, responses to fluid therapy and prognosis. The classification system used simple clinical variables and could help to design ARDS trials in the future.

The relationship between high-dose corticosteroid treatment and mortality in acute respiratory distress syndrome: a retrospective and observational study using a nationwide administrative database in Japan

Background

In the 1980s, randomized-controlled trials showed that high-dose corticosteroid treatment did not improve the mortality of acute respiratory distress syndrome (ARDS). However, while the diagnostic criteria for ARDS have since changed, and supportive therapies have been improved, no randomized-controlled trials have revisited this issue since 1987; thus, the effect of high-dose corticosteroid treatment may be different in this era. We evaluated the effect of high-dose corticosteroid treatment in patients with ARDS using a nationwide administrative database in Japan in a retrospective and observational study.

Methods

This study was performed with a large population using the 2012 Japanese nationwide administrative database (diagnostic procedure combination). We evaluated the mortality of ARDS patients receiving or not receiving high-dose corticosteroid treatment within 7 days of hospital admission. We employed propensity score weighting with a Cox proportional hazards model in order to minimize the bias associated with the retrospective collection of data on baseline characteristics and compared the mortality between the high-dose and non-high-dose corticosteroid groups.

Results

Data from 2707 patients were used; 927 patients were treated with high-dose corticosteroid and 1780 patients were treated without high-dose corticosteroid, within 7 days of admission. After adjusting for confounds, mortality rates within 3 months were significantly higher in the high-dose corticosteroid group compared to the non-high-dose corticosteroid group (weighted hazard ratio: 1.59; 95% CI: 1.37-1.84; P <  0.001).

Conclusions

Our results suggest that high-dose corticosteroid treatment does not improve the prognosis of patients with ARDS, even in this era. However, this study has limitations owing to its retrospective and observational design.

High-dose steroid therapy for acute respiratory distress syndrome lacking common risk factors: predictors of outcome

Aim

Acute respiratory distress syndrome (ARDS) is a life-threatening lung disease that usually occurs in patients with the underling risk factors that triggers lung inflammation. We sometimes encounter patients with ARDS lacking common risk factors. Recent studies have indicated the effectiveness of corticosteroids for this cohort. However, the characteristics of survivors with ARDS who lack common risk factors, and who received high-dose methylprednisolone pulse therapy (MPPT), are not known.

Methods

We undertook a retrospective study of patients with ARDS lacking common risk factors, who received i.v. MPPT for 3 days. The patients (n = 46) were classified into two groups, survivors (n = 23) and non-survivors (n = 23), based on their survival at 60 days after the initiation of MPPT, and their clinical and radiological parameters were evaluated.

Results

The patient characteristics and disease severity of the two groups were comparable. The percentage of consolidation/(ground-glass attenuation [GGA] + consolidation) on the chest computed tomography scans of survivors was significantly lower than that of non-survivors (survivors, 5.63% [2.31-13.8] versus non-survivors, 27.2% [5.97-41.4]; P = 0.01). In the stratified analysis, the percentage of consolidation/(GGA + consolidation) was significantly associated with 60-day survival.

Conclusions

Our results show that the percentage of consolidation/(GGA + consolidation) on the chest CT scans is an independent prognostic factor for patients with ARDS lacking common risk factors after MPPT.

Causal mediation analysis in the context of clinical research

Clinical researches usually collected numerous intermediate variables besides treatment and outcome. These variables are often incorrectly treated as confounding factors and are thus controlled using a variety of multivariable regression models depending on the types of outcome variable. However, these methods fail to disentangle underlying mediating processes. Causal mediation analysis (CMA) is a method to dissect total effect of a treatment into direct and indirect effect. The indirect effect is transmitted via mediator to the outcome. The mediation package is designed to perform CMA under the assumption of sequential ignorability. It reports average causal mediation effect (ACME), average direct effect (ADE) and total effect. Also, the package provides visualization tool for these estimated effects. Sensitivity analysis is designed to examine whether the results are robust to the violation of the sequential ignorability assumption since the assumption has been criticized to be too strong to be satisfied in research practice.