Review:Acute lung injury/acute respiratory distress syndrome (ALI/ARDS): the mechanism,present strategies and future perspectives of therapies

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS), which manifests as non-cardiogenic pulmonary edema, respiratory distress and hypoxemia, could be resulted from various processes that directly or indirectly injure the lung. Extensive investigations in experimental models and humans with ALI/ARDS have revealed many molecular mechanisms that offer therapeutic opportunities for cell or gene therapy. Herein the present strategies and future perspectives of the treatment for ALI/ARDS, include the ventilatory, pharmacological, as well as cell therapies.

Basic and clinical research progress in acute lung injury/acute respiratory distress syndrome

Acute lung injury(ALI)/acute respiratory distress syndrome(ARDS) is an acute progressive respiratory failure caused by severe infection, trauma, shock, poisoning, inhaled harmful gas, acute pancreatitis, and pathological obstetrics. ALI and ARDS demonstrate similar pathophysiological changes. The severe stage of ALI is defined as ARDS. At present, a significant progress has been achieved in the study of the pathogenesis and pathophysiology of ALI/ARDS. Whether or not ALI/ARDS patients can recover depends on the degree of lung injury, extra-pulmonary organ damage, original primary disease of a patient, and adequacy in supportive care. Conservative infusion strategies and protective lung ventilation reduce ARDS disability and mortality. In this study, the pathogenesis of ALI/ARDS, lung injury, molecular mechanisms of lung repair, and conservative infusion strategies and pulmonary protective ventilation are reviewed comprehensively.

Protective mechanism of quercetin in alleviating sepsis-related acute respiratory distress syndrome based on network pharmacology and in vitro experiments

BACKGROUND:Sepsis-related acute respiratory distress syndrome(ARDS)has a high mortality rate,and no effective treatment is available currently.Quercetin is a natural plant product with many pharmacological activities,such as antioxidative,anti-apoptotic,and anti-inflammatory effects.This study aimed to elucidate the protective mechanism of quercetin against sepsis-related ARDS.METHODS:In this study,network pharmacology and in vitro experiments were used to investigate the underlying mechanisms of quercetin against sepsis-related ARDS.Core targets and signaling pathways of quercetin against sepsis-related ARDS were screened and were verified by in vitro experiments.RESULTS:A total of 4,230 targets of quercetin,360 disease targets of sepsis-related ARDS,and 211 intersection targets were obtained via database screening.Among the 211 intersection targets,interleukin-6(IL-6),tumor necrosis factor(TNF),albumin(ALB),AKT serine/threonine kinase 1(AKT1),and interleukin-1β(IL-1β)were identified as the core targets.A Gene Ontology(GO)enrichment analysis revealed 894 genes involved in the inflammatory response,apoptosis regulation,and response to hypoxia.Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analysis identified 106 pathways.After eliminating and generalizing,the hypoxia-inducible factor-1(HIF-1),TNF,nuclear factor-κB(NF-κB),and nucleotide-binding and oligomerization domain(NOD)-like receptor signaling pathways were identified.Molecular docking revealed that quercetin had good binding activity with the core targets.Moreover,quercetin blocked the HIF-1,TNF,NF-κB,and NODlike receptor signaling pathways in lipopolysaccharide(LPS)-induced murine alveolar macrophage(MH-S)cells.It also suppressed the inflammatory response,oxidative reactions,and cell apoptosis.CONCLUSION:Quercetin ameliorates sepsis-related ARDS by binding to its core targets and blocking the HIF-1,TNF,NF-κB,and NOD-like receptor signaling pathways to reduce inflammation,cell apoptosis,and oxidative stress.

Clinical significance of platelet mononuclear cell aggregates in patients with sepsis and acute respiratory distress syndrome

BACKGROUND The diagnosis of sepsis combined with acute respiratory distress syndrome(ARDS)has increased owing to the enhanced awareness among medical profes-sionals and the continuous development of modern medical technologies,while early diagnosis of ARDS still lacks specific biomarkers.One of the main patho-genic mechanisms of sepsis-associated ARDS involves the actions of various pathological injuries and inflammatory factors,such as platelet and white blood cells activation,leading to an increase of surface adhesion molecules.These adhesion molecules further form platelet-white blood cell aggregates,including platelet-mononuclear cell aggregates(PMAs).PMAs has been identified as one of the markers of platelet activation,here we hypothesize that PMAs might play a potential biomarker for the early diagnosis of this complication.METHODS We selected 72 hospitalized patients diagnosed with sepsis as the study population between March 2019 and March 2022.Among them,30 patients with sepsis and ARDS formed the study group,while 42 sepsis patients without ARDS comprised the control group.After diagnosis,venous blood samples were imme-diately collected from all patients.Flow cytometry was employed to analyze the expression of PMAs,platelet neutrophil aggregates(PNAs),and platelet aggregates(PLyAs)in the serum.Additionally,the Acute Physiology and Chronic Health Evaluation(APACHE)II score was calculated for each patient,and receiver operating characteristic curves were generated to assess diagnostic value.RESULTS The study found that the levels of PNAs and PLyAs in the serum of the study group were higher than those in the control group,but the difference was not statistically significant(P>0.05).However,the expression of PMAs in the serum of the study group was significantly upregulated(P<0.05)and positively correlated with the APACHE II score(r=0.671,P<0.05).When using PMAs as a diagnostic indicator,the area under the curve value was 0.957,indicating a high diagnostic value(P<0.05).Furthermore,the optimal cutoff value was 8.418%,with a diagnostic sensitivity of 0.819 and specificity of 0.947.CONCLUSION In summary,the serum levels of PMAs significantly increase in patients with sepsis and ARDS.Therefore,serum PMAs have the potential to become a new biomarker for clinically diagnosing sepsis complicated by ARDS.

Steroids in acute respiratory distress syndrome:A panacea or still a puzzle?

Acute respiratory distress syndrome(ARDS)is a unique entity marked by various etiologies and heterogenous pathophysiologies.There remain concerns regarding the efficacy of particular medications for each severity level apart from respiratory support.Among several pharmacotherapies which have been examined in the treatment of ARDS,corticosteroids,in particular,have demonstrated potential for improving the resolution of ARDS.Nevertheless,it is imperative to consider the potential adverse effects of hyperglycemia,susceptibility to hospital-acquired infections,and the development of intensive care unit acquired weakness when administering corticosteroids.Thus far,a multitude of trials spanning several decades have investigated the role of corticosteroids in ARDS.Further stringent trials are necessary to identify particular subgroups before implementing corticosteroids more widely in the treatment of ARDS.This review article provides a concise overview of the most recent evidence regarding the role and impact of corticosteroids in the management of ARDS.

Single Lung Acute Respiratory Distress Syndrome

Hydatid disease or echinococcosis is a zoonotic parasitic disease. The lungs are the second most commonly affected organ after the liver. Intrathoracic and extrapulmonary hydatid disease can affect the pleura, mediastinum, heart, diaphragm, and chest wall. The unusual location or complications of thoracic hydatid disease can present both a diagnostic problem and a therapeutic and surgical problem. We present results of a case of multilocular thoracic hydatid disease complicated by aortic wall erosion and cystic fistula in a 23-year-old patient who developed acute respiratory distress syndrome (ARDS) on the 4th day after emergency pneumonectomy. The surgery was carried out under the conditions of the auxiliary artificial circulation. This case represented a serious clinical situation with the highest risk to life. The need for immediate respiratory support was due to the development of severe respiratory failure, and the presence of direct and indirect harmful factors of ARDS. The correct choice of modes and techniques of mechanical ventilation resulted in significant and sustained improvement in gas exchange parameters without hemodynamic disorders with a further favorable outcome.

Effect of different ventilation methods combined with pulmonary surfactant on neonatal acute respiratory distress syndrome

BACKGROUND Acute respiratory distress syndrome precipitates is widespread pulmonary injury in impacted individuals,the neonatal respiratory distress syndrome(NRDS),primarily observed in preterm infants,represents a prevalent critical condition in neonatal clinical settings.AIM To investigate the clinical efficacy of various ventilation strategies combined with pulmonary surfactant(PS)therapy in the treatment of NRDS.METHODS A total of 20 neonates diagnosed with respiratory distress syndrome,admitted between May 2021 and June 2022,were randomly assigned to either a research group or a control group.Neonates in the research group received treatment involving high-frequency oscillatory ventilation(HFOV)in conjunction with PS.In contrast,neonates in the control group were administered either controlled mechanical ventilation or synchronous intermittent mandatory ventilation,combined with PS.Arterial blood samples from the neonates in both groups were collected before treatment,as well as 6 h,12 h,24 h,and 48 h post-treatment.These samples underwent blood gas analysis,with measurements taken for pH value,partial pressures of oxygen(O_(2))and carbon dioxide.Concurrently,data was collected on the duration of ventilator use,length of hospitalization time,O_(2) treatment time,treatment outcomes,and complications of the ventilator.RESULTS From 6-48 h post-treatment,both groups demonstrated significant improvements in arterial blood pH and oxygen partial pressure,along with a significant decrease in carbon dioxide partial pressure compared to pre-treatment values(P<0.05).Although these changes progressed over time,there were no significant differences between the two groups(P>0.05).However,the research group had significantly lower X-ray scores,shorter hospitalization time,and less time on O_(2) therapy compared to the control group(P<0.05).Mortality rates were similar between the two groups(P>0.05),but the research group had a significantly lower incidence of complications(P<0.05).CONCLUSION The integration of HFOV combine with PS has proven to effectively expedite the treatment duration,decrease the occurrence of complications,and secure the therapeutic efficacy in managing NRDS.

Acute respiratory distress syndrome and severe pneumonitis after atezolizumab plus bevacizumab for hepatocellular carcinoma treatment:A case report

BACKGROUND Hepatocellular carcinoma(HCC)is one of the most common cancers worldwide and has a high mortality.However,the treatment options for advanced HCC are limited to tyrosine kinase inhibitors,such as sorafenib and lenvatinib.Since previous regimens have an insufficient efficacy,the combination therapy of atezolizumab and bevacizumab(Ate/Bev)has been investigated,which showed an improvement in progression-free and overall survival.However,the adverse events of this combination therapy in advanced HCC have not been established.Herein,we report a novel case of an unresectable HCC and acute respiratory distress syndrome(ARDS)after a combination therapy of Ate/Bev.CASE SUMMARY An 82-year-old male visited our outpatient clinic for an incidentally detected liver mass.Liver magnetic resonance imaging and enhanced chest computed tomography(CT)were performed,which showed arterial hyperenhancement with washout in delayed phase suggesting HCC,and a well-defined metastatic solid nodule,respectively.F-18 fluorodeoxyglucose positron emission tomography(PET)-CT exhibited multiple hypermetabolic lesions in the iliac bone,lumbar vertebrae,and femur.Because of the high burden of the intrahepatic tumor,transarterial radioembolization was initially performed;after 37 d,a combination therapy of Ate/Bev was administered.The patient visited the emergency department three days after Ate/Bev treatment complaining of dyspnea.He was diagnosed with severe pneumonitis based on CT.Despite administering oxygen via a high-flow nasal cannula,the P/F ratio was only 74;therefore,the patient was diagnosed with ARDS based on the overall examination results.Low tidal volume with high positive end-expiratory pressure,sedative agents combined with a neuromuscular blocker,and a systemic steroid were promptly applied to manage the ARDS.However,the patient did not recover from the hypoxia and expired 31 h after being admitted.CONCLUSION Clinicians should be aware of severe pneumonitis due to the immune-related adverse events of this combination therapy,and patients should be closely monitored after therapy.

Current status and prospects of basic research and clinical application of mesenchymal stem cells in acute respiratory distress syndrome

Acute respiratory distress syndrome(ARDS)is a common and clinically devastating disease that causes respiratory failure.Morbidity and mortality of patients in intensive care units are stubbornly high,and various complications severely affect the quality of life of survivors.The pathophysiology of ARDS includes increased alveolar–capillary membrane permeability,an influx of protein-rich pulmonary edema fluid,and surfactant dysfunction leading to severe hypoxemia.At present,the main treatment for ARDS is mechanical treatment combined with diuretics to reduce pulmonary edema,which primarily improves symptoms,but the prognosis of patients with ARDS is still very poor.Mesenchymal stem cells(MSCs)are stromal cells that possess the capacity to self-renew and also exhibit multilineage differentiation.MSCs can be isolated from a variety of tissues,such as the umbilical cord,endometrial polyps,menstrual blood,bone marrow,and adipose tissues.Studies have confirmed the critical healing and immunomodulatory properties of MSCs in the treatment of a variety of diseases.Recently,the potential of stem cells in treating ARDS has been explored via basic research and clinical trials.The efficacy of MSCs has been shown in a variety of in vivo models of ARDS,reducing bacterial pneumonia and ischemia-reperfusion injury while promoting the repair of ventilator-induced lung injury.This article reviews the current basic research findings and clinical applications of MSCs in the treatment of ARDS in order to emphasize the clinical prospects of MSCs.

Right ventricle dysfunction does not predict mortality in patients with SARS-CoV-2-related acute respiratory distress syndrome on extracorporeal membrane oxygenation support

BACKGROUND The prognostic role of right ventricle dilatation and dysfunction(RVDD)has not been elucidated in patients with coronavirus disease(COVID)-related respiratory failure refractory to standard treatment needing extracorporeal membrane oxygenation(ECMO)support.AIM To assess whether pre veno-venous(VV)ECMO RVDD were related to inintensive care unit(ICU)mortality.METHODS We enrolled 61 patients with COVID-related acute respiratory distress syndrome refractory to conventional treatment submitted to VV ECMO and consecutively admitted to our ICU(an ECMO referral center)from 31th March 2020 to 31th August 2021.An echocardiographic exam was performed immediately before VV ECMO implantation.RESULTS Males were prevalent(73.8%)and patients with a body mass index>30 kg/m^(2) were the majority(46/61,75%).The overall in-ICU mortality rate was 54.1%(33/61).RVDD was detectable in more than half of the population(34/61,55.7%)and associated with higher simplified organ functional assessment(SOFA)values(P=0.029)and a longer mechanical ventilation duration prior to ECMO support(P=0.046).Renal replacement therapy was more frequently needed in RVDD patients(P=0.002).A higher in-ICU mortality(P=0.024)was observed in RVDD patients.No echo variables were independent predictors of in-ICU death.CONCLUSION In patients with COVID-related respiratory failure on ECMO support,RVDD(dilatation and dysfunction)is a common finding and identifies a subset of patients characterized by a more severe disease(as indicated by higher SOFA values and need of renal replacement therapy)and by a higher in-ICU mortality.RVDD(also when considered separately)did not result independently associated with in-ICU mortality in these patients.

Effects of Early-stage Phased Rehabilitation Training on Acute Respiratory Distress Syndrome:A Systematic Review and Meta-analysis

[Objectives]To systematically evaluate the effects of early-stage phased rehabilitation training on the oxygenation index,ICU length of stay,duration of mechanical ventilation,and occurrence of complications(ventilator-associated pneumonia,pressure ulcers,delirium)in ARDS patients,thus contributing evidence for the clinical application of early-stage phased rehabilitation training.[Methods]The China National Knowledge Infrastructure(CNKI),Wanfang,and other databases were searched.Literature screening,data extraction,and systematic analysis of the included studies were performed using Revman software.[Results]Thirteen randomized controlled trials involving a total of 860 patients were included in this review.The results of the meta-analysis showed that compared to the traditional rehabilitation training group,the early-stage phased rehabilitation training group demonstrated a significant increase in the oxygenation index of ARDS patients[SMD=1.18,95%CI(1.01,1.35),P<0.01],with statistically significant differences.Furthermore,there were significant reductions in ICU length of stay[SMD=-0.70,95%CI(-0.90,-0.50),P<0.01],duration of mechanical ventilation[SMD=-1.15,95%CI(-1.36,-0.94),P<0.01],and occurrence of complications[OR=0.16,95%CI(0.10,0.26),P<0.01],all of which were statistically significant.[Conclusions]Early-stage phased pulmonary rehabilitation training for ARDS patients effectively improves the oxygenation index,shortens ICU length of stay and duration of mechanical ventilation,and reduces complications.These findings support the clinical application and promotion of early-stage phased rehabilitation training.

Ulinastatin for acute lung injury and acute respiratory distress syndrome: A systematic review and meta-analysis

AIM: To investigate the efficacy and safety of ulinastatin for patients with acute lung injury(ALI) and those with acute respiratory distress syndrome(ARDS).METHODS: A systematic review of randomized controlled trials(RCTs) of ulinastatin for ALI/ARDS was conducted. Oxygenation index, mortality rate [intensive care unit(ICU) mortality rate, 28-d mortality rate] and length of ICU stay were compared between ulinastatin group and conventional therapy group. Meta-analysis was performed by using Rev Man 5.1.RESULTS: Twenty-nine RCTs with 1726 participants were totally included, the basic conditions of which were similar. No studies discussed adverse effect. Oxygenation index was reported in twenty-six studies(1552 patients). Ulinastatin had a significant effect in improving oxygenation [standard mean difference(SMD) = 1.85, 95%CI: 1.42-2.29, P < 0.00001, I2 = 92%]. ICUmortality and 28-d mortality were respectively reported in eighteen studies(987 patients) and three studies(196 patients). We found that ulinastatin significantly decreased the ICU mortality [I2 = 0%, RR = 0.48, 95%CI: 0.38-0.59, number needed to treat(NNT) = 5.06, P < 0.00001], while the 28-d mortality was not significantly affected(I2 = 0%, RR = 0.78, 95%CI: 0.51-1.19, NNT = 12.66, P = 0.24). The length of ICU stay(six studies, 364 patients) in the ulinastatin group was significantly lower than that in the control group(SMD =-0.97, 95%CI:-1.20--0.75, P < 0.00001, I2 = 86%). CONCLUSION: Ulinastatin seems to be effective for ALI and ARDS though most trials included were of poor quality and no information on safety was provided.

Acute respiratory distress syndrome and lung injury: Pathogenetic mechanism and therapeutic implication

To review possible mechanisms and therapeutics for acute lung injury(ALI) and acute respiratory distress syndrome(ARDS). ALI/ARDS causes high mortality. The risk factors include head injury, intracranial disorders, sepsis, infections and others. Investigations have indicated the detrimental role of nitric oxide(NO) through the inducible NO synthase(i NOS). The possible therapeutic regimen includes extracorporeal membrane oxygenation, prone position, fluid and hemodynamic management and permissive hypercapnic acidosis etc. Other pharmacological treatments are anti-inflammatory and/or antimicrobial agents, inhalation of NO, glucocorticoids, surfactant therapy and agents facilitating lung water resolution and ion transports. β-adrenergic agonists are able to accelerate lung fluid and ion removal and to stimulate surfactant secretion. In con-scious rats, regular exercise training alleviates the endotoxin-induced ALI. Propofol and N-acetylcysteine exert protective effect on the ALI induced by endotoxin. Insulin possesses anti-inflammatory effect. Pentobarbital is capable of reducing the endotoxin-induced ALI. In addition, nicotinamide or niacinamide abrogates the ALI caused by ischemia/reperfusion or endotoxemia. This review includes historical retrospective of ALI/ARDS, the neurogenic pulmonary edema due to head injury, the detrimental role of NO, the risk factors, and the possible pathogenetic mechanisms as well as therapeutic regimen for ALI/ARDS.

Acute lung injury and acute respiratory distress syndrome： experimental and clinical investigations

尖锐的肺损害(所有) 或尖锐呼吸悲痛症候群(ARDS ) 能与各种各样的混乱被联系。最近的调查在各种各样的混乱引起的 ALI 或 ARDS 的病原的机制上与临床的调查者和病理学家合作包含了临床的研究。这文学评论包括一篇摘要历史 ALI/ARDS 回顾，神经原的肺的浮肿由于从我们的实验室的头损害，长期的试验性的研究和临床的调查，有害角色没有，风险因素，和象为 ALI/ARDS 的治疗学的政体一样的可能的病原的机制。

Effects of dynamic ventilatory factors on ventilatorinduced lung injury in acute respiratory distress syndrome dogs

BACKGROUND:Mechanical ventilation is a double-edged sword to acute respiratory distress syndrome(ARDS) including lung injury,and systemic inflammatory response high tidal volumes are thought to increase mortality.The objective of this study is to evaluate the effects of dynamic ventilatory factors on ventilator induced lung injury in a dog model of ARDS induced by hydrochloric acid instillation under volume controlled ventilation and to investigate the relationship between the dynamic factors and ventilator-induced lung injuries(VILI) and to explore its potential mechanisms.METHODS:Thirty-six healthy dogs were randomly divided into a control group and an experimental group.Subjects in the experimental group were then further divided into four groups by different inspiratory stages of flow.Two mL of alveolar fluid was aspirated for detection of IL-8 and TNF-α.Lung tissue specimens were also extracted for total RNA,IL-8 by western blot and observed under an electronic microscope.RESULTS:IL-8 protein expression was significantly higher in group B than in groups A and D.Although the IL-8 protein expression was decreased in group C compared with group B,the difference was not statistically significant.The TNF-α ray degree of group B was significantly higher than that in the other groups(P<0.01),especially in group C(P>0.05).The alveolar volume of subjects in group B was significantly smaller,and cavity infiltration and cell autolysis were marked with a significant thicker alveolar septa,disorder of interval structures,and blurring of collagenous and elastic fiber structures.A large number of necrotic debris tissue was observed in group B.CONCLUSION:Mechanical ventilation with a large tidal volume,a high inspiratory flow and a high ventilation frequency can cause significant damage to lung tissue structure.It can significantly increase the expression of TNF-α and IL-8 as well as their mRNA expression.Furthermore,the results of our study showed that small tidal ventilation significantly reduces the release of proinflammatory media.This finding suggests that greater deterioration in lung injury during ARDS is associated with high inspiratory flow and high ventilation rate.

Pro-resolution of inflammation： a potential strategy for treatment of acute lung injury/acute respiratory distress syndrome

Acute lung injury （ALI） and its more severe form acute respiratory distress syndrome （ARDS） are acute clinical complications,which cause significant morbidity and mortality.1 Despite recent advances in our understanding of the pathophysiology and diagnosis of ALI and ARDS,the clinical strategies are restricted to mechanical ventilation and supportive treatments,such as fluid conservative management and glucocorticoids （GCs）.Mechanical ventilation is a common and life-saving strategy for the patients with ARDS.Lung protective ventilation strategy with lower tidal volumes can improve hypoxia and reduce the mortality in patients with ARDS.

Effects of pulmonary stretch reflex on lung injury in rabbits with acute respiratory distress syndrome

BACKGROUND： Pulmonary stretch reflex plays an important role in regulation of respiratorymovement. This study aimed to evaluate the effect of pulmonary stretch reflex on lung injury inrabbits with acute respiratory distress syndrome （ARDS）.METHODS： ARDS rabbits were given intratracheal infusion of hydrochloric acid and ventilatedwith neurally adjusted ventilatory assistance （NAVA） with a tidal volume （VT） of 6 mL/kg and theelectrical activity of diaphragm （EAdi）-determined positive end expiratory pressure. After isolation ofthe bilateral vagus nerve trunk, the rabbits were randomized into two groups： sham operation （SHAM）group （n=5） and bilateral vagotomy （VAG） group （n=5）. Gas exchange and respiratory mechanicswere detected at baseline, after lung injury and 1, 2, and 3 hours after ventilation respectively.Pulmonary permeability index, pathological changes and infl ammatory response were also measured.RESULTS： Compared with the SHAM group, PaO2/FiO2 in the VAG group decreased signifi cantly2 and 3 hours after ventilation （P〈0.05）. There was no significant difference in PaCO2 betweenthe SHAM and VAG groups （P〉0.05）, and the VAG group had a high VT, peak pressure （Ppeak）,and mean pressure （Pm） compared with the SHAM group 1, 2, 3 hours after ventilation （P〈0.05）.Compared to the SHAM group, dead space fraction （VD/VT） and respiratory system elastance （Ers）in the VAG group increased （P〈0.05） and static pulmonary compliance （Cst） decreased markedly（P〈0.05） after ventilation for 3 hours. Lung wet/dry weight ratio （W/D） （8.4±1.2 vs. 6.6±1.0）, lung injuryscore （6.3±1.8 vs. 3.8±1.3）, tumor necrosis factor-# （TNF-#） （779±372 pg/mL vs. 355±130 pg/mL）and interleukin-8 （IL-8） （169±21 pg/mL vs. 118±17 pg/mL） increased significantly in the VAG groupcompared with the SHAM group （P〈0.05）.CONCLUSION： Lung injury is aggravated after bilateral vagotomy, demonstrating thatpulmonary stretch refl ex may have protective effect on the lung.

Effect of High Frequency Oscillatory Ventilation on EVLW and Lung Capillary Permeability of Piglets with Acute Respiratory Distress Syndrome Caused by Pulmonary and Extrapulmonary Insults

The effect of high frequency oscillatory ventilation（HFOV） at early stage on hemodynamic parameters, extravascular lung water（EVLW）, lung capillary permeability, CC16 and s ICAM-1 in piglets with pulmonary or extrapulmonary acute respiratory distress syndrome（ARDS） was explored. Central vein pressure（CVP） and pulse indicator continuous cardiac output（Pi CCO） were monitored in 12 anesthetized and intubated healthy piglets. Pulmonary ARDS（ARDSp） and extrapulmonary ARDS（ARDSexp） models were respectively established by lung lavage of saline solution and intravenous injection of oleic acid. Then the piglets received HFOV for 4 h. EVLW index（EVLWI）, EVLW/intratroracic blood volume（ITBV） and pulmonary vascular permeability index（PVPI） were measured before and after modeling（T0 and T1）, and T2（1 h）, T3（2 h）, T4（3 h） and T5（4 h） after HFOV. CC16 and s ICAM-1 were also detected at T1 and T5. Results showed at T1, T3, T4 and T5, EVLWI was increased more significantly in ARDSp group than in ARDSexp group（P〈0.05）. The EVLWI in ARDSp group was increased at T1（P=0.008）, and sustained continuously within 2 h（P=0.679, P=0.216）, but decreased at T4（P=0.007） and T5（P=0.037）. The EVLWI in ARDSexp group was also increased at T1（P=0.003）, but significantly decreased at T3（P=0.002） and T4（P=0.019）. PVPI was increased after modeling in both two groups（P=0.004, P=0.012）, but there was no significant change within 4 h（T5） under HFOV in ARDSp group, while PVPI showed the increasing trends at first, then decreased in ARDSexp group after HFOV. The changes of EVLW/ITBV were similar to those of PVPI. No significant differences were found in ΔEVLWI（P=0.13）, ΔPVPI（P=0.28） and ΔEVLW/ITBV between the two groups（P=0.63）. The significant decreases in both CC16 and s ICAM-1 were found in both two groups 4 h after HFOV, but there was no significant difference between the two groups. It was concluded that EVLWI and lung capillary permeability were markedly increased in ARDSp and ARDSexp groups. EVLW could be decreased 4 h after the HFOV treatment. HFOV, EVLW/ITBV and PVPI were increased slightly at first, and then decreased in ARDSexp group, while in ARDSp group no significant difference was found after modeling. No significant differences were found in the decreases in EVLW and lung capillary permeability 4 h after HFOV.

Mitofusion 2 Overexpression Decreased Proliferation of Human Embryonic Lung Fibroblasts in Acute Respiratory Distress Syndrome through Inhibiting RAS-RAF-1-ERK1/2 Pathway

Acute respiratory distress syndrome(ARDS)is one of the most fatal diseases worldwide.Pulmonary fibrosis occurs early in ARDS,and its severity plays a crucial role in ARDS mortality rate.Some studies suggested that fibroproliferation is an essential mechanism in ARDS.Mitofusion2(Mfn2)overexpression plays a role in inhibiting cell proliferation.However,the role and potential mechanism of Mfn2 on the proliferation of fibroblasts is still unknown.In this study,we aimed at exploring the effect of Mfn2 on the human embryonic lung fibroblasts(HELF)and discussed its related mechanism.The HELF were treated with the Mfn2 overexpressing lentivirus(adv-Mfn2).The cell cycle was detected by flow cytometry.MTT,PCR and Western blotting were used to investigate the effect of Mfn2 on the proliferation of the HELF,collagen expression,the RAS-RAF-1-ERK1/2 pathway and the expression of cycle-related proteins(p21,p27,Rb,Raf-1,p-Raf-1,Erk1/2 and p-Erk1/2).The co-immunoprecipitation assay was used to explore the interaction between Mfn2 and Ras.The results showed that the overexpression of Mfn2 inhibited the proliferation of the HELF and induced the cell cycle arrest at the G0/G1 phase.Meanwhile,Mfn2 also inhibited the expression of collagen I,p-Erk and p-Raf-1.In addition,an interaction between Mfn2 and Ras existed in the HELF.This study suggests that the overexpression of Mfn2 can decrease the proliferation of HELF in ARDS,which was associated with the inhibition of the RAS-RAF-1-ERK1/2 pathway.The results may offer a potential therapeutic intervention for patients with ARDS.

VASCULAR ENDOTHELIAL INJURIES AND CHANGES OF BLOOD COAGULATION AND FIBRINOLYSIS INDEXES IN PATIENTS WITH ACUTE RESPIRATORY DISTRESS SYNDROME

Objective To study endothelial damage by observing changes of circulating endothelial cells (CECs) in blood, coagula-tion and fibrinolysis index in patients with acute respiratory distress syndrome. Methods CECs were separated by isopycnic centrifugation method in 14 patients with acute lung injury (ALI), 7 patients with acute respiratory distress syndrome (ARDS), 10 intensive care unit (ICU) controls, and 15 healthy controls. Plasma prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FG), fibrin degradation products (FDP), and D-dimer were examined simultaneously. Acute physiology and chronic health evaluation (APACHE)Ⅱand lung injury score (LIS) were recorded to evaluate severity of illness and lung injury. Results (1) The number of CECs in ALI (10.4 ±2.3) and ARDS groups (16.1 ±2.7) was higher than that in the healthy (1.9 ±0.5) (P< 0.01). In both ALI and ARDS, the number of CECs correlated with APACHEⅡ(r=0.55, P< 0.05 and r=0.62, P< 0.05, respectively)and LIS (r=0.60, P< 0.05 and r=0.53, P< 0.05, respectively). CEC number was negatively correlated with PaO 2 in ALI and ARDS (r=-0.49, P< 0.05 and r=-0.64, P< 0.05, respectively). (2) The level of FDP and D-dimer were higher in ALI and ARDS patients than that in ICU and healthy control groups (P< 0.05). The level of FG in ARDS group was significantly higher than in the ICU and healthy control groups (P< 0.05). But in ALI group, the level of FG was significantly higher than only healthy control group (P< 0.05). Conclusions Endothelial cell damage occurs in ARDS patients, which may play a major role in the pathophysiology of ARDS. Changes of endothelial cell activation and damage markers, such as CECs, plasma coagulation and fibrinolysis index, to some extent reflect severity of illness and lung injury in ARDS.