Comparison of systemic cytokine levels in patients with acute respiratory distress syndrome, severe pneumonia, and controls

Ophiopogonin D alleviates acute lung injury by regulating inflammation via the STAT3/A20/ASK1 axis

BACKGROUND

Acute lung injury (ALI) is characterized by acute pulmonary inflammatory infiltration. Alveolar epithelial cells (AECs) release numerous pro-inflammatory cytokines, which result in the pathological changes seen in ALI. Ophiopogonin D (OD), extracted from the roots of Ophiopogon japonicus (Thunb.) Ker Gawl. (Liliaceae), reduces inflammation; however, the efficacy of OD in ALI has not been reported and the underlying molecular mechanisms remain unclear.

PURPOSE

This study investigated the anti-inflammatory effects of OD, as well as the underlying mechanisms, in AECs and a mouse ALI model.

METHODS

Lipopolysaccharide (LPS) and tumor necrosis factor-α (TNF-α) were used to stimulate macrophages and A549 cells, and a mouse ALI model was established by intratracheal LPS administration. The anti-inflammatory effects and mechanisms of OD in the TNF-α-induced in vitro inflammation model was evaluated using real-time quantitative polymerase chain reaction qPCR), enzyme-linked immunosorbent assay (ELISA), western blotting, nuclear and cytoplasmic protein extraction, and immunofluorescence. The in vivo anti-inflammatory activity of OD was evaluated using hematoxylin and eosin staining, qPCR, ELISA, and western blotting.

RESULTS

The bronchoalveolar lavage fluid and lung tissue of LPS-induced ALI mice exhibited increased TNF-α expression. TNF-α induced a significantly greater pro-inflammatory effect in AECs than LPS. OD reduced inflammation and mitogen-activated protein kinase (MAPK) and transcription factor p65 phosphorylation in vivo and in vitro and promoted signal transducer and activator of transcription 3 (STAT3) phosphorylation and A20 expression, thereby inducing apoptosis signal-regulating kinase 1 (ASK1) proteasomal degradation.

CONCLUSION

OD exerts an anti-inflammatory effect by promoting STAT3-dependent A20 expression and ASK1 degradation. OD may therefore have therapeutic value in treating ALI and other TNF-α-related inflammatory diseases.

IRF1 Mediates Growth Arrest and the Induction of a Secretory Phenotype in Alveolar Epithelial Cells in Response to Inflammatory Cytokines IFNγ/TNFα

In COVID-19, cytokine release syndrome can cause severe lung tissue damage leading to acute respiratory distress syndrome (ARDS). Here, we address the effects of IFNγ, TNFα, IL-1β and IL-6 on the growth arrest of alveolar A549 cells, focusing on the role of the IFN regulatory factor 1 (IRF1) transcription factor. The efficacy of JAK1/2 inhibitor baricitinib has also been tested. A549 WT and IRF1 KO cells were exposed to cytokines for up to 72 h. Cell proliferation and death were evaluated with the resazurin assay, analysis of cell cycle and cycle-regulator proteins, LDH release and Annexin-V positivity; the induction of senescence and senescence-associated secretory phenotype (SASP) was evaluated through β-galactosidase staining and the quantitation of secreted inflammatory mediators. While IL-1 and IL-6 proved ineffective, IFNγ plus TNFα caused a proliferative arrest in A549 WT cells with alterations in cell morphology, along with the acquisition of a secretory phenotype. These effects were STAT and IRF1-dependent since they were prevented by baricitinib and much less evident in IRF1 KO than in WT cells. In alveolar cells, STATs/IRF1 axis is required for cytokine-induced proliferative arrest and the induction of a secretory phenotype. Hence, baricitininb is a promising therapeutic strategy for the attenuation of senescence-associated inflammation.

High Respiratory and Cardiac Drive Exacerbate Secondary Lung Injury in Patients With Critical Illness

The high respiratory and cardiac drive is essential to the host-organ unregulated response. When a primary disease and an unregulated secondary response are uncontrolled, the patient may present in a high respiratory and cardiac drive state. High respiratory drive can cause damage to the lungs, pulmonary circulation, and diaphragm, while high cardiac drive can lead to fluid leakage and infiltration as well as pulmonary interstitial edema. A "respiratory and cardiac dual high drive" state may be a sign of an unregulated response and can lead to secondary lung injury through the increase of transvascular pressure and pulmonary microcirculation injury. Ultrasound examination of the lung, heart, and diaphragm is important when evaluating the phenotype of high respiratory drive in critically ill patients. Ultrasound assessment can guide sedation, analgesia, and antistress treatment and reduce the risk of high respiratory and cardiac drive-induced lung injury in these patients.

Subphenotypes of Acute Respiratory Distress Syndrome: Advancing Towards Precision Medicine

Acute respiratory distress syndrome (ARDS) is a common cause of severe hypoxemia defined by the acute onset of bilateral non-cardiogenic pulmonary edema. The diagnosis is made by defined consensus criteria. Supportive care, including prevention of further injury to the lungs, is the only treatment that conclusively improves outcomes. The inability to find more advanced therapies is due, in part, to the highly sensitive but relatively non-specific current syndromic consensus criteria, combining a heterogenous population of patients under the umbrella of ARDS. With few effective therapies, the morality rate remains 30% to 40%. Many subphenotypes of ARDS have been proposed to cluster patients with shared combinations of observable or measurable traits. Subphenotyping patients is a strategy to overcome heterogeneity to advance clinical research and eventually identify treatable traits. Subphenotypes of ARDS have been proposed based on radiographic patterns, protein biomarkers, transcriptomics, and/or machine-based clustering of clinical and biological variables. Some of these strategies have been reproducible across patient cohorts, but at present all have practical limitations to their implementation. Furthermore, there is no agreement on which strategy is the most appropriate. This review will discuss the current strategies for subphenotyping patients with ARDS, including the strengths and limitations, and the future directions of ARDS subphenotyping.

Dipeptidyl-peptidase 3 and IL-6: potential biomarkers for diagnostics in COVID-19 and association with pulmonary infiltrates

Coronavirus SARS-CoV-2 spread worldwide, causing a respiratory disease known as COVID-19. The aim of the present study was to examine whether Dipeptidyl-peptidase 3 (DPP3) and the inflammatory biomarkers IL-6, CRP, and leucocytes are associated with COVID-19 and able to predict the severity of pulmonary infiltrates in COVID-19 patients versus non-COVID-19 patients. 114 COVID-19 patients and 35 patients with respiratory infections other than SARS-CoV-2 were included in our prospective observational study. Blood samples were collected at presentation to the emergency department. 102 COVID-19 patients and 28 non-COVID-19 patients received CT imaging (19 outpatients did not receive CT imaging). If CT imaging was available, artificial intelligence software (CT Pneumonia Analysis) was used to quantify pulmonary infiltrates. According to the median of infiltrate (14.45%), patients who obtained quantitative CT analysis were divided into two groups (> median: 55 COVID-19 and nine non-COVID-19, ≤ median: 47 COVID-19 and 19 non-COVID-19). DPP3 was significantly elevated in COVID-19 patients (median 20.85 ng/ml, 95% CI 18.34-24.40 ng/ml), as opposed to those without SARS-CoV-2 (median 13.80 ng/ml, 95% CI 11.30-17.65 ng/ml; p < 0.001, AUC = 0.72), opposite to IL-6, CRP (each p = n.s.) and leucocytes (p < 0.05, but lower levels in COVID-19 patients). Regarding binary logistic regression analysis, higher DPP3 concentrations (OR = 1.12, p < 0.001) and lower leucocytes counts (OR = 0.76, p < 0.001) were identified as significant and independent predictors of SARS-CoV-2 infection, as opposed to IL-6 and CRP (each p = n.s.). IL-6 was significantly increased in patients with infiltrate above the median compared to infiltrate below the median both in COVID-19 (p < 0.001, AUC = 0.78) and in non-COVID-19 (p < 0.05, AUC = 0.81). CRP, DPP3, and leucocytes were increased in COVID-19 patients with infiltrate above median (each p < 0.05, AUC: CRP 0.82, DPP3 0.70, leucocytes 0.67) compared to infiltrate below median, opposite to non-COVID-19 (each p = n.s.). Regarding multiple linear regression analysis in COVID-19, CRP, IL-6, and leucocytes (each p < 0.05) were associated with the degree of pulmonary infiltrates, as opposed to DPP3 (p = n.s.). DPP3 showed the potential to be a COVID-19-specific biomarker. IL-6 might serve as a prognostic marker to assess the extent of pulmonary infiltrates in respiratory patients.

Effects of in-house and commercial extracts of the allergenic mite Tyrophagus putrescentiae on murine and human cell responses

Mites are among the major sources of domestic and occupational allergens worldwide, and continuous exposure to these allergens leads to chronic airway inflammation. One of the most allergenic species is the storage mite Tyrophagus putrescentiae (Schrank). Protein extracts are produced from this mite for tests that help the clinical diagnosis (via prick test), treatment, and monitoring of disease progression in patients who had positive results for allergic reactions. Therefore, the aim of the present study was to evaluate the cell viability of RAW 264.7 and L929 cells when exposed to in-house raw protein extracts of T. putrescentiae compared to a commercial product, as well as quantify TNF-α secretion by RAW 264.7. Additionally, this study quantified the effect of these extracts in IgE secretion in total blood of people affected by this mite. The study found similarity between the in-house extract and the commercial extract as they had equivalent TNF-α secretion. Additionally, viabilities of RAW 264.7 and L929 exposed to the in-house extract were compatible with viabilities of cells exposed to the commercial extract, with no cytotoxicity at the concentrations tested. Results corroborated the hypothesis that the extract produced in-house would be equivalent to the commercial extract in allergic patients when the IgE was quantified. This study is the first to show the cytotoxicity of T. putrescentiae extracts, and to provide a quantitative analysis of TNF-α and IgE.

Recent progress and prospects for anti-cytokine therapy in preclinical and clinical acute lung injury

Acute respiratory distress syndrome (ARDS) is a heterogeneous cause of respiratory failure that has a rapid onset, a high mortality rate, and for which there is no effective pharmacological treatment. Current evidence supports a critical role of excessive inflammation in ARDS, resulting in several cytokines, cytokine receptors, and proteins within their downstream signalling pathways being putative therapeutic targets. However, unsuccessful trials of anti-inflammatory drugs have thus far hindered progress in the field. In recent years, the prospects of precision medicine and therapeutic targeting of cytokines coevolving into effective treatments have gained notoriety. There is an optimistic and growing understanding of ARDS subphenotypes as well as advances in treatment strategies and clinical trial design. Furthermore, large trials of anti-cytokine drugs in patients with COVID-19 have provided an unprecedented amount of information that could pave the way for therapeutic breakthroughs. While current clinical and nonclinical ARDS research suggest relatively limited potential in monotherapy with anti-cytokine drugs, combination therapy has emerged as an appealing strategy and may provide new perspectives on finding safe and effective treatments. Accurate evaluation of these drugs, however, also relies on well-founded experimental research and the implementation of biomarker-guided stratification in future trials. In this review, we provide an overview of anti-cytokine therapy for acute lung injury and ARDS, highlighting the current preclinical and clinical evidence for targeting the main cytokines individually and the therapeutic prospects for combination therapy.

Acute organ injury and long-term sequelae of severe pneumococcal infections

Streptococcus pneumoniae (Spn) is a major public health problem, as it is a main cause of otitis media, community-acquired pneumonia, bacteremia, sepsis, and meningitis. Acute episodes of pneumococcal disease have been demonstrated to cause organ damage with lingering negative consequences. Cytotoxic products released by the bacterium, biomechanical and physiological stress resulting from infection, and the corresponding inflammatory response together contribute to organ damage accrued during infection. The collective result of this damage can be acutely life-threatening, but among survivors, it also contributes to the long-lasting sequelae of pneumococcal disease. These include the development of new morbidities or exacerbation of pre-existing conditions such as COPD, heart disease, and neurological impairments. Currently, pneumonia is ranked as the 9^th leading cause of death, but this estimate only considers short-term mortality and likely underestimates the true long-term impact of disease. Herein, we review the data that indicates damage incurred during acute pneumococcal infection can result in long-term sequelae which reduces quality of life and life expectancy among pneumococcal disease survivors.

Reduction of primary graft dysfunction using cytokine adsorption during organ preservation and after lung transplantation

Despite improvements, lung transplantation remains hampered by both a scarcity of donor organs and by mortality following primary graft dysfunction (PGD). Since acute respiratory distress syndrome (ARDS) limits donor lungs utilization, we investigated cytokine adsorption as a means of treating ARDS donor lungs. We induced mild to moderate ARDS using lipopolysaccharide in 16 donor pigs. Lungs were then treated with or without cytokine adsorption during ex vivo lung perfusion (EVLP) and/or post-transplantation using extracorporeal hemoperfusion. The treatment significantly decreased cytokine levels during EVLP and decreased levels of immune cells post-transplantation. Histology demonstrated fewer signs of lung injury across both treatment periods and the incidence of PGD was significantly reduced among treated animals. Overall, cytokine adsorption was able to restore lung function and reduce PGD in lung transplantation. We suggest this treatment will increase the availability of donor lungs and increase the tolerability of donor lungs in the recipient.

Lung transplantation is hindered by the scarcity of organs and by mortality following primary graft dysfunction. Here, the authors show that cytokine absorption can be used in donor lungs during ex vivo lung perfusion and post-transplant, and leads to restored lung function and reduced primary graft dysfunction in animal models.

Association between inflammatory biomarkers and acute respiratory distress syndrome or acute lung injury risk : A systematic review and meta-analysis

Background

The relationship between acute respiratory distress syndrome (ARDS)/acute lung injury (ALI) and levels of certain inflammatory factors remains controversial. The purpose of this meta-analysis was to summarize the available studies evaluating the association between levels of inflammatory factors and ARDS/ALI incidence.

Methods

We searched the PubMed, EmBase, and Cochrane databases for studies published up to July 2017. For each inflammatory factor, a random effects model was employed to pool results from different studies.

Results

We identified 63 studies that included 6243 patients in our meta-analysis. Overall, the results indicated that the levels of angiopoietin (ANG)-2 (standard mean difference, SMD: 1.34; P < 0.001), interleukin (IL)-1β (SMD: 0.92; P = 0.012), IL‑6 (SMD: 0.66; P = 0.005), and tumor necrosis factor (TNF)-α (SMD: 0.98; P = 0.001) were significantly higher in patients with ARDS/ALI than in unaffected individuals. No significant differences were observed between patients with ARDS/ALI and unaffected individuals in terms of the levels of IL‑8 (SMD: 0.61; P = 0.159), IL-10 (SMD: 1.10; P = 0.231), and plasminogen activator inhibitor (PAI)-1 (SMD: 0.70; P = 0.060).

Conclusions

ARDS/ALI is associated with a significantly elevated levels of ANG‑2, IL-1β, IL‑6, and TNF‑α, but not with IL‑8, IL-10, and PAI‑1 levels.

Supplementary Information

The online version of this article (10.1007/s00508-021-01971-3) contains supplementary material, which is available to authorized users.

Nanotechnology based advanced therapeutic strategies for targeting interleukins in chronic respiratory diseases

Both communicable and non-communicable chronic respiratory conditions have accorded for suffering of millions of people of all ages and stated to be leading cause of death, morbidity, economic and social pressures, and disability-adjusted life-years (DALYs) worldwide. These illnesses impair patient's health and negatively impacts families and society, particularly in low and middle-income countries. Chronic respiratory diseases (CRDs) affect different organs of respiratory system, involving airways, parenchyma, and pulmonary vasculature. As the number of respiratory diseases are exponentially escalating but still the stakeholders are not paying attention towards its serious complications. Currently, the treatment being used primarily focusses only on alleviating symptoms of these illness rather delivering the therapeutic agent at target site for optimal care and/or prevention. Lately, extensive research is being conducted on airways and systemic inflammation, oxidative stress, airway, or parenchymal rehabilitation. From which macrophages, neutrophils, and T cells, as well as structural cells as fibroblasts, epithelial, endothelial, and smooth muscle cells have been found to be active participants that are involved in these chronic respiratory diseases. The pathogenesis of all these chronic respiratory diseases gets caused differently via mediators and proteins, including cytokines, chemokines, growth factors and oxidants. Presently, the target of prescription therapies is to reduce the inflammation of airways and relieve the airway contraction. In all studies, cytokines have been found to play an imperative role in fostering chronic airway inflammation and remodelling. Owing to the limitations of conventional treatments, the current review aims to summarize the current knowledge about the chronic respiratory disease and discuss further about the various conventional methods that can be used for treating this ailment. Additionally, it also highlights and discusses about the advanced drug delivery system that are being used for targeting the interleukins for the treatment of CRDs.

PM2.5-induced lung injury is attenuated in macrophage-specific NLRP3 deficient mice

Fine particulate matter (PM2.5) is one of the most important components of environmental pollutants and is associated with lung injury. Pyroptosis, a form of programmed cell death mainly mediated by the NLRP3 inflammasome, has been reported to be involved in sepsis-induced or ischemia/reperfusion-induced lung injury. However, the specific mechanisms of pyroptosis in PM2.5-induced lung injury are not yet clear. We constructed macrophage-specific NLRP3 knockout mice to explore the mechanism of PM2.5-induced lung injury in terms of inflammatory response, oxidative stress, and apoptosis levels, including the relationship between these effects and pyroptosis. The results disclosed that PM2.5 exposure increased the infiltration of macrophages and leukocytes and the secretion of inflammatory cytokines, including TNF-α and IL-6, in lung tissue. The activity of antioxidant enzymes, including SOD, GSH-PX, and CAT, significantly decreased, while MDA, the end product of lipid oxidation, remarkably increased. The level of apoptosis in lung tissue, measured by the TUNEL assay and apoptosis-related proteins (BAX and BCL-2), was significantly increased. Macrophage-specific NLRP3 knockout could offset these effects. We further observed that PM2.5 treatment activated the NLRP3 inflammasome and subsequently induced pyroptosis, as evidenced by the increased production of IL-1β and IL-18 and the increase of the protein levels of NLRP3, ASC, caspase-1, and GSDMD, which were inhibited when NLRP3 was knocked out in macrophages. Taken together, these results revealed that NLRP3-mediated macrophage pyroptosis promoted PM2.5-induced lung injury through aggravating inflammation, oxidative stress, and apoptosis. Targeting the inhibition of NLRP3-mediated macrophage pyroptosis provides a new way to study lung injury induced by the exposure to PM2.5.

Monitoring lung injury with particle flow rate in LPS- and COVID-19-induced ARDS

In severe acute respiratory distress syndrome (ARDS), extracorporeal membrane oxygenation (ECMO) is a life-prolonging treatment, especially among COVID-19 patients. Evaluation of lung injury progression is challenging with current techniques. Diagnostic imaging or invasive diagnostics are risky given the difficulties of intra-hospital transportation, contraindication of biopsies, and the potential for the spread of infections, such as in COVID-19 patients. We have recently shown that particle flow rate (PFR) from exhaled breath could be a noninvasive, early detection method for ARDS during mechanical ventilation. We hypothesized that PFR could also measure the progress of lung injury during ECMO treatment. Lipopolysaccharide (LPS) was thus used to induce ARDS in pigs under mechanical ventilation. Eight were connected to ECMO, whereas seven animals were not. In addition, six animals received sham treatment with saline. Four human patients with ECMO and ARDS were also monitored. In the pigs, as lung injury ensued, the PFR dramatically increased and a particular spike followed the establishment of ECMO in the LPS-treated animals. PFR remained elevated in all animals with no signs of lung recovery. In the human patients, in the two that recovered, PFR decreased. In the two whose lung function deteriorated while on ECMO, there was increased PFR with no sign of recovery in lung function. The present results indicate that real-time monitoring of PFR may be a new, complementary approach in the clinic for measurement of the extent of lung injury and recovery over time in ECMO patients with ARDS.

The impact of cytokine levels in young South African children with and without HIV-associated acute lower respiratory infections

Altered host immune responses are considered to play a key role in the pathogenesis of acute lower respiratory infections (ALRI). The existing literature on cytokine responses in ALRI is largely focussed on adults from developed countries and there are few reports describing the role of cytokines in childhood ALRI, particularly in African or human immunodeficiency virus (HIV)-infected populations. To measure systemic cytokine levels in blood plasma from young South African children with and without ALRI and with and without HIV to determine associations between cytokine responses and disease status and respiratory viral identification. Blood plasma samples were collected from 106 hospitalized ALRI cases and 54 non-ALRI controls less than 2 years of age. HIV status was determined. Blood plasma concentrations of 19 cytokines, 7 chemokines, and 4 growth factors (epidermal growth factor, fibroblast growth factor-basic, hepatocyte growth factor, and vascular endothelial) were measured using The Human Cytokine 30-Plex Panel. Common respiratory viruses were identified by PCR. Mean cytokine concentrations for G-CSF, interferon (IFN)-γ, interleukin (IL)-5, and MCP-1 were significantly higher in ALRI cases than in nonrespiratory controls. Within the ALRI cases, several cytokines were higher in children with a virus compared with children without a virus. Mean cytokine concentrations for IFN-α, IFN-γ, IL-4, IL-5, IL-13, tumour necrosis factor-α, and MIP-1α were significantly lower in HIV-infected cases than in HIV-uninfected cases, while IP-10 and monokine induced by interferon-γ were significantly higher in HIV-infected cases than in HIV-uninfected cases. Certain cytokines are likely to play an important role in the host immune response to ALRI. HIV-infected children have impaired inflammatory responses to respiratory infections compared with HIV-uninfected children.

Potential bangle (Zingiber montanum J.König) rhizome extract as a supplement to prevent and reduce symptoms of Covid-19

The morbidity and mortality rates due to Covid-19 are increasing day by day, to overcome this, we urgently need a better treatment strategy, therefore various ways and strategies for this must be pursued. The purpose of the present review is to explain that the rhizome of bangle (Zingiber montanum) has great potential to increase antibodies and reduce symptoms of acute respiratory distress syndrome (ARDS), which also seems suitable for treating Covid-19. Method: This review is looking for the results of scientific research from various sources, regarding the efficacy of bangle (Zingiber montanum) rhizome which is strongly suspected to be able to prevent, and reduce the symptoms that occur in COVID-19. The results showed that the bangle rhizome extract had activity as immunomodulatory, antiviral and reduced symptoms such as what happened in COVID-19. Conclusion: Bangle rhizome extract has dozens of nutritious substances and has multifunctional activities, and it can be postulated that among the benefits of bangle rhizome extract it is able to prevent and reduce symptoms that occur in Covid-19, and preclinical studies and clinical studies are needed to prove this postulate.

Dexmedetomidine alleviates pulmonary edema through the epithelial sodium channel (ENaC) via the PI3K/Akt/Nedd4-2 pathway in LPS-induced acute lung injury

Dexmedetomidine (Dex), a highly selective α2-adrenergic receptor (α2AR) agonist, has an anti-inflammatory property and can alleviate pulmonary edema in lipopolysaccharide (LPS)-induced acute lung injury (ALI), but the mechanism is still unclear. In this study, we attempted to investigate the effect of Dex on alveolar epithelial sodium channel (ENaC) in the modulation of alveolar fluid clearance (AFC) and the underlying mechanism. Lipopolysaccharide (LPS) was used to induce acute lung injury (ALI) in rats and alveolar epithelial cell injury in A549 cells. In vivo, Dex markedly reduced pulmonary edema induced by LPS through promoting AFC, prevented LPS-induced downregulation of α-, β-, and γ-ENaC expression, attenuated inflammatory cell infiltration in lung tissue, reduced the concentrations of TNF-α, IL-1β, and IL-6, and increased concentrations of IL-10 in bronchoalveolar lavage fluid (BALF). In A549 cells stimulated with LPS, Dex attenuated LPS-mediated cell injury and the downregulation of α-, β-, and γ-ENaC expression. However, all of these effects were blocked by the PI3K inhibitor LY294002, suggesting that the protective role of Dex is PI3K-dependent. Additionally, Dex increased the expression of phosphorylated Akt and reduced the expression of Nedd4-2, while LY294002 reversed the effect of Dex in vivo and in vitro. Furthermore, insulin-like growth factor (IGF)-1, a PI3K agonists, promoted the expression of phosphorylated Akt and reduced the expression of Nedd4-2 in LPS-stimulated A549 cells, indicating that Dex worked through PI3K, and Akt and Nedd4-2 are downstream of PI3K. In conclusion, Dex alleviates pulmonary edema by suppressing inflammatory response in LPS-induced ALI, and the mechanism is partly related to the upregulation of ENaC expression via the PI3K/Akt/Nedd4-2 signaling pathway.

Systematic review of diagnostic methods for acute respiratory distress syndrome

Rationale

Acute respiratory distress syndrome (ARDS) is currently diagnosed by the Berlin definition, which does not include a direct measure of pulmonary oedema, endothelial permeability or pulmonary inflammation. We hypothesised that biomarkers of these processes have good diagnostic accuracy for ARDS.

Methods

Medline and Scopus were searched for original diagnostic studies using minimally invasive testing. Primary outcome was the diagnostic accuracy per test and was categorised by control group. The methodological quality was assessed with QUADAS-2 tool. Biomarkers that had an area under the receiver operating characteristic curve (AUROCC) of >0.75 and were studied with minimal bias against an unselected control group were considered to be promising.

Results

Forty-four articles were included. The median AUROCC for all evaluated tests was 0.80 (25th to 75th percentile: 0.72–0.88). The type of control group influenced the diagnostic accuracy (p=0.0095). Higher risk of bias was associated with higher diagnostic accuracy (AUROCC 0.75 for low-bias, 0.77 for intermediate-bias and 0.84 for high-bias studies; p=0.0023). Club cell protein 16 and soluble receptor for advanced glycation end-products in plasma and two panels with biomarkers of oxidative stress in breath showed good diagnostic accuracy in low-bias studies that compared ARDS patients to an unselected intensive care unit (ICU) population.

Conclusion

This systematic review revealed only four diagnostic tests fulfilling stringent criteria for a promising biomarker in a low-bias setting. For implementation into the clinical setting, prospective studies in a general unselected ICU population with good methodological quality are needed.

Accuracy of diagnosis of acute respiratory distress syndrome (ARDS) is associated with risk of bias. There is a lack of validated diagnostic tests in an unbiased setting, emphasising the need for quality driven diagnostic research in ARDS.https://bit.ly/2GfPAvf

Novel Perspectives Regarding the Pathology, Inflammation, and Biomarkers of Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is an acute inflammation of the lung resulting from damage to the alveolar-capillary membrane, and it is diagnosed using a combination of clinical and physiological variables. ARDS develops in approximately 10% of hospitalised patients with pneumonia and has a mortality rate of approximately 40%. Recent research has identified several biomarkers associated with ARDS pathophysiology, and these may be useful for diagnosing and monitoring ARDS. They may also highlight potential therapeutic targets. This review summarises our current understanding of those clinical biomarkers: (1) biomarkers of alveolar and bronchiolar injury, (2) biomarkers of endothelial damage and coagulation, and (3) biomarkers for treatment responses.

Respiratory drive in the acute respiratory distress syndrome: pathophysiology, monitoring, and therapeutic interventions

Neural respiratory drive, i.e., the activity of respiratory centres controlling breathing, is an overlooked physiologic variable which affects the pathophysiology and the clinical outcome of acute respiratory distress syndrome (ARDS). Spontaneous breathing may offer multiple physiologic benefits in these patients, including decreased need for sedation, preserved diaphragm activity and improved cardiovascular function. However, excessive effort to breathe due to high respiratory drive may lead to patient self-inflicted lung injury (P-SILI), even in the absence of mechanical ventilation. In the present review, we focus on the physiological and clinical implications of control of respiratory drive in ARDS patients. We summarize the main determinants of neural respiratory drive and the mechanisms involved in its potentiation, in health and ARDS. We also describe potential and pitfalls of the available bedside methods for drive assessment and explore classical and more “futuristic” interventions to control drive in ARDS patients.

Genomic and Genetic Approaches to Deciphering Acute Respiratory Distress Syndrome Risk and Mortality

Significance: Acute respiratory distress syndrome (ARDS) is a severe, highly heterogeneous critical illness with staggering mortality that is influenced by environmental factors, such as mechanical ventilation, and genetic factors. Significant unmet needs in ARDS are addressing the paucity of validated predictive biomarkers for ARDS risk and susceptibility that hamper the conduct of successful clinical trials in ARDS and the complete absence of novel disease-modifying therapeutic strategies. Recent Advances: The current ARDS definition relies on clinical characteristics that fail to capture the diversity of disease pathology, severity, and mortality risk. We undertook a comprehensive survey of the available ARDS literature to identify genes and genetic variants (candidate gene and limited genome-wide association study approaches) implicated in susceptibility to developing ARDS in hopes of uncovering novel biomarkers for ARDS risk and mortality and potentially novel therapeutic targets in ARDS. We further attempted to address the well-known health disparities that exist in susceptibility to and mortality from ARDS. Critical Issues: Bioinformatic analyses identified 201 ARDS candidate genes with pathway analysis indicating a strong predominance in key evolutionarily conserved inflammatory pathways, including reactive oxygen species, innate immunity-related inflammation, and endothelial vascular signaling pathways. Future Directions: Future studies employing a system biology approach that combines clinical characteristics, genomics, transcriptomics, and proteomics may allow for a better definition of biologically relevant pathways and genotype-phenotype connections and result in improved strategies for the sub-phenotyping of diverse ARDS patients via molecular signatures. These efforts should facilitate the potential for successful clinical trials in ARDS and yield a better fundamental understanding of ARDS pathobiology.

Alleviation of Inflammatory Response of Pulmonary Fibrosis in Acute Respiratory Distress Syndrome by Puerarin via Transforming Growth Factor (TGF-β1)

BACKGROUND Acute respiratory distress syndrome (ARDS) in infants is acute and progressive hypoxic respiratory failure caused by various extrapulmonary pathogenic factors besides cardiogenic factors. Diffuse alveolar injury and progression to pulmonary fibrosis are pathological features of ARDS. The present study sought to determine how puerarin influences the inflammatory response caused by pulmonary fibrosis in ARDS in infants. MATERIAL AND METHODS The human lung fibroblasts cell line HLF1 was treated with different concentrations of puerarin in different groups for various times. TGF-ß1 was overexpressed by TGF-ß1 (2 ng/mL) in routine experiments, and the treated cells and culture supernatant were collected for analysis in each step. Cell apoptosis was measured by flow cytometry, TUNEL assay, and detection of caspase 3 and Bcl-2. Cell proliferation was assessed by CCK-8 assay. Real-time PCR and Western blot assay were used to assess mRNA and protein levels of TGF-ß1 and Smad3, respectively. The related cytokines were assessed by ELISA. RESULTS Results showed that puerarin promoted the apoptosis and inhibited the proliferation of HLF1 cells. Caspase 3 was upregulated, whereas Bcl-2, TGF-ß1, and Smad3 were downregulated by puerarin. IL-1, IL-2, and IL-4, secreted by HLF1 cells, were reduced, but IL-10 showed the opposite trend. When TGF-ß1 was overexpressed, Smad3 was promoted, and IL-1, IL-2, and IL-4 was increased in HLF1 cells. Finally, overexpression of TGF-ß1 reversed the effect of puerarin in HLF1 cells. CONCLUSIONS Puerarin regulated the proliferation and apoptosis of pulmonary fibrosis cells, and affected the secretion of inflammatory cytokines. Thus, puerarin alleviated the inflammatory response resulting from pulmonary fibrosis by regulating the TGF-ß1/Smad3 pathway in infants with ARDS.

IL-33-mediated IL-13 secretion by ST2+ Tregs controls inflammation after lung injury

Acute respiratory distress syndrome is an often fatal disease that develops after acute lung injury and trauma. How released tissue damage signals, or alarmins, orchestrate early inflammatory events is poorly understood. Herein we reveal that IL-33, an alarmin sequestered in the lung epithelium, is required to limit inflammation after injury due to an unappreciated capacity to mediate Foxp3+ Treg control of local cytokines and myeloid populations. Specifically, Il33-/- mice are more susceptible to lung damage-associated morbidity and mortality that is typified by augmented levels of the proinflammatory cytokines and Ly6Chi monocytes in the bronchoalveolar lavage fluid. Local delivery of IL-33 at the time of injury is protective but requires the presence of Treg cells. IL-33 stimulates both mouse and human Tregs to secrete IL-13. Using Foxp3Cre × Il4/Il13fl/fl mice, we show that Treg expression of IL-13 is required to prevent mortality after acute lung injury by controlling local levels of G-CSF, IL-6, and MCP-1 and inhibiting accumulation of Ly6Chi monocytes. Our study identifies a regulatory mechanism involving IL-33 and Treg secretion of IL-13 in response to tissue damage that is instrumental in limiting local inflammatory responses and may shape the myeloid compartment after lung injury.

Prognosis value of Serum Cytokine levels among burn-induced ards patients

XX.

Molecular and Immune Biomarkers in Acute Respiratory Distress Syndrome: A Perspective From Members of the Pulmonary Pathology Society

Acute respiratory distress syndrome (ARDS) is a multifactorial syndrome with high morbidity and mortality rates, characterized by deficiency in gas exchange and lung mechanics that lead to hypoxemia, dyspnea, and respiratory failure. Histologically, ARDS is characterized by an acute, exudative phase, combining diffuse alveolar damage and noncardiogenic edema, followed by a later fibroproliferative phase. Despite an enhanced understanding of ARDS pathogenesis, the capacity to predict the development of ARDS and to risk-stratify patients with the disease remains limited. Biomarkers may help to identify patients at the greatest risk of developing ARDS, to evaluate response to therapy, to predict outcome, and to improve clinical trials. The ARDS pathogenesis is presented in this article, as well as concepts and information on biomarkers that are currently used clinically or are available for laboratory use by academic and practicing pathologists and the developing and validating of new assays, focusing on the assays' major biologic roles in lung injury and/or repair and to ultimately suggest innovative, therapeutic approaches.

Down-regulation of toll-like receptor 4 alleviates intestinal ischemia reperfusion injury and acute lung injury in mice

Intestinal ischemia reperfusion (IR) injury is a critical problem, which can cause intestinal injury locally and acute lung injury (ALI) distally by inflammatory responses and oxidative stress. Toll-like receptor 4 (TLR4) is involved in innate immune and inflammatory responses. This study was to determine whether TLR4 mutant can attenuate intestinal and lung injuries after intestinal IR. Wild type (WT) and TLR4 mutant mice were submitted to intestinal IR by occluding the superior mesenteric artery. Histological assessment of the intestine and the lung were conducted by HE staining. The levels of proinflammatory cytokines, oxidative stress markers, apoptotic index and other mediators were measured. In addition, a 24-hour survival study was performed. Histological assessment showed that intestinal IR caused serious injuries in the intestine and the lung, corroborated by increased proinflammatory cytokines in the circulation. TLR4 mutant suppressed the histological injuries as demonstrated by significantly decreased pathological scores. Consistent with the morphological results, the TLR4 mutant mice exhibited remarkably lowered cytokine expressions in the intestine (TNF-α, IL-6, IL-1β, and NF-κB) and the lung (NO, iNOS, MCP-1, MIP-2, NF-κB, and Caspase-3). ALT and creatinine were also significantly dampened in the liver and kidney, respectively. Furthermore, the survival rate over the course of 24 hours was significantly improved. Collectively, the findings reveal that TLR4 mutant significantly abated the intestinal IR injury and ALI at least in part by alleviating the inflammatory response and oxidative stress.

Alternative pre-mRNA splicing of Toll-like receptor signaling components in peripheral blood mononuclear cells from patients with ARDS

A key physiological feature of acute respiratory distress syndrome (ARDS) is inflammation. Toll-like receptor (TLR) signaling is required to combat the infection that underlies many ARDS cases but also contributes to pathological inflammation. Several TLR signaling pathway genes encoding positive effectors of inflammation also produce alternatively spliced mRNAs encoding negative regulators of inflammation. An imbalance between these isoforms could contribute to pathological inflammation and disease severity. To determine whether splicing in TLR pathways is altered in patients with ARDS, we monitored alternative splicing of MyD88 and IRAK1, two genes that function in multiple TLR pathways. The MyD88 and IRAK1 genes produce long proinflammatory mRNAs (MyD88_L and IRAK1) and shorter anti-inflammatory mRNAs (MyD88_S and IRAK1c). We quantified mRNA encoding inflammatory cytokines and MyD88 and IRAK1 isoforms in peripheral blood mononuclear cells (PBMCs) from 104 patients with ARDS and 30 healthy control subjects. We found that MyD88 pre-mRNA splicing is altered in patients with ARDS in a proinflammatory direction. We also observed altered MyD88 isoform levels in a second critically ill patient cohort, suggesting that these changes may not be unique to ARDS. Early in ARDS, PBMC IRAK1c levels were associated with patient survival. Despite the similarities in MyD88 and IRAK1 alternative splicing observed in previous in vitro studies, there were differences in how MyD88 and IRAK1 alternative splicing was altered in patients with ARDS. We conclude that pre-mRNA splicing of TLR signaling genes is altered in patients with ARDS, and further investigation of altered splicing may lead to novel prognostic and therapeutic approaches.

Protective effects of tenuigenin on Staphylococcus aureus-induced pneumonia in mice

Pneumonia is the leading cause of death in infants and young children. Staphylococcus aureus (S.aureus) is one of the most important bacteria that leads to pneumonia. Tenuigenin (TGN), a major active component isolated from the root of the Chinese herb Polygala tenuifolia, has been known to have anti-inflammatory effect. In this study, we aimed to investigate the protective effects of TGN on S.aureus-induced pneumonia in mice. The results showed that TGN significantly attenuated S.aureus-induced lung histopathological changes. TGN also inhibited lung wet/dry (W/D) ratio, and inflammatory cytokines TNF-α and IL-1β production. Furthermore, S.aureus-induced NF-κB activation was significantly inhibited by the treatment of TGN. In conclusion, the results of this study showed that TGN protected against S.aureus-induced pneumonia by inhibiting NF-κB activation. TGN might be a potential agent in the treatment of pneumonia induced by S.aureus.

Anti-TNFα therapy in inflammatory lung diseases

Increased levels of tumor necrosis factor (TNF) α have been linked to a number of pulmonary inflammatory diseases including asthma, chronic obstructive pulmonary disease (COPD), acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), sarcoidosis, and interstitial pulmonary fibrosis (IPF). TNFα plays multiple roles in disease pathology by inducing an accumulation of inflammatory cells, stimulating the generation of inflammatory mediators, and causing oxidative and nitrosative stress, airway hyperresponsiveness and tissue remodeling. TNFα-targeting biologics, therefore, present a potentially highly efficacious treatment option. This review summarizes current knowledge on the role of TNFα in pulmonary disease pathologies, with a focus on the therapeutic potential of TNFα-targeting agents in treating inflammatory lung diseases.

Inflammatory Responses Regulating Alveolar Ion Transport during Pulmonary Infections

The respiratory epithelium is lined by a tightly balanced fluid layer that allows normal O₂ and CO₂ exchange and maintains surface tension and host defense. To maintain alveolar fluid homeostasis, both the integrity of the alveolar–capillary barrier and the expression of epithelial ion channels and pumps are necessary to establish a vectorial ion gradient. However, during pulmonary infection, auto- and/or paracrine-acting mediators induce pathophysiological changes of the alveolar–capillary barrier, altered expression of epithelial Na,K-ATPase and of epithelial ion channels including epithelial sodium channel and cystic fibrosis membrane conductance regulator, leading to the accumulation of edema and impaired alveolar fluid clearance. These mediators include classical pro-inflammatory cytokines such as TGF-β, TNF-α, interferons, or IL-1β that are released upon bacterial challenge with Streptococcus pneumoniae, Klebsiella pneumoniae, or Mycoplasma pneumoniae as well as in viral infection with influenza A virus, pathogenic coronaviruses, or respiratory syncytial virus. Moreover, the pro-apoptotic mediator TNF-related apoptosis-inducing ligand, extracellular nucleotides, or reactive oxygen species impair epithelial ion channel expression and function. Interestingly, during bacterial infection, alterations of ion transport function may serve as an additional feedback loop on the respiratory inflammatory profile, further aggravating disease progression. These changes lead to edema formation and impair edema clearance which results in suboptimal gas exchange causing hypoxemia and hypercapnia. Recent preclinical studies suggest that modulation of the alveolar–capillary fluid homeostasis could represent novel therapeutic approaches to improve outcomes in infection-induced lung injury.

Effect of nebulized budesonide on respiratory mechanics and oxygenation in acute lung injury/acute respiratory distress syndrome: Randomized controlled study

Background:

We tested the hypothesis that nebulized budesonide would improve lung mechanics and oxygenation in patients with early acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS) during protective mechanical ventilation strategy without adversely affecting systemic hemodynamics.

Methods:

Patients with ALI/ARDS were included and assigned into two groups; budesonide group (30 cases) in whom 1 mg–2 ml budesonide suspension was nebulized through the endotracheal tube and control group (30 cases) in whom 2 ml saline (placebo) were nebulized instead of budesonide. This regimen was repeated every 12 h for three successive days alongside with constant ventilator settings in both groups. Hemodynamics, airway pressures, and PaO₂/FiO₂ were measured throughout the study period (72 h) with either nebulized budesonide or saline. Furthermore, tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) were analyzed serologically as markers of inflammation at pre- and post-nebulization sessions.

Results:

We found a significant difference between the two groups regarding PaO₂/FiO₂ (P = 0.023), peak (P = 0.021), and plateau (P = 0.032) airway pressures. Furthermore, TNF-α, IL-1β, and IL-6 were significantly reduced after budesonide nebulizations. No significant difference was found between the two groups regarding hemodynamic variables.

Conclusion:

Nebulized budesonide improved oxygenation, peak, and plateau airway pressures and significantly reduced inflammatory markers (TNF-α, IL-1β and IL-6) without affecting hemodynamics.

Trial Registry:

Australian New Zealand Clinical Trial Registry (ANZCTR) at the number: ACTRN12615000373572.

The balance between the serum levels of IL-6 and IL-10 cytokines discriminates mild and severe acute pneumonia

BACKGROUND

To identify markers for earlier diagnosis of severe pneumonia, we assess the correlation between serum cytokine profile of children with different pneumonia severity.

METHODS

In 25 hospitalized children, 7 with mild pneumonia and 18 with severe pneumonia, the serum concentration of 11 cytokines in three sampling times were dosed. Statistical analysis included parametric and non-parametric tests, Pearson correlation and ROC curve for cut-off definition of cytokines.

RESULTS

At admission, IL-6 serum levels were high in mild or severe pneumonia, and was associated to vomiting (P = 0.019) in both groups; and also to dyspnea (P = 0.012) and white blood cell count (P = 0.045) in patients with severe pneumonia. IL-10 levels were also high in patients with pneumonia and were associated to lymphocytosis (P = 0.025). The ROC curve of the IL-6:IL-10 serum levels ratio discriminated severe pneumonia cases at admission, and persistence of infection in the third day of antibiotic therapy, with positive predictive values of 93% and 89%, respectively.

CONCLUSIONS

The balance between IL-6 and IL-10 serum levels showed to be a more discriminative marker for severity definition and evaluation of recovery in patients with pneumonia.

Standardized myrtol attenuates lipopolysaccharide induced acute lung injury in mice

CONTEXT

Standardized myrtol, an essential oil containing primarily cineole, limonene and α-pinene, has been used for treating nasosinusitis, bronchitis and chronic obstructive pulmonary disease (COPD).

OBJECTIVE

To investigate the effects of standardized myrtol in a model of acute lung injury (ALI) induced by lipopolysaccharides (LPS).

MATERIALS AND METHODS

Male BALB/c mice were treated with standardized myrtol for 1.5 h prior to exposure of atomized LPS. Six hours after LPS challenge, lung injury was determined by the neutrophil recruitment, cytokine levels and total protein concentration in the bronchoalveolar lavage fluid (BALF) and myeloperoxidase (MPO) activity in the lung tissue. Additionally, pathological changes and NF-κB activation in the lung were examined by haematoxylin and eosin staining and western blot, respectively.

RESULTS

In LPS-challenged mice, standardized myrtol at a dose of 1200 mg/kg significantly inhibited the neutrophile counts (from 820.97 ± 142.44 to 280.42 ± 65.45, 10³/mL), protein concentration (from 0.331 ± 0.02 to 0.183 ± 0.01, mg/mL) and inflammatory cytokines level (TNF-α: from 6072.70 ± 748.40 to 2317.70 ± 500.14, ng/mL; IL-6: from 1184.85 ± 143.58 to 509.57 ± 133.03, ng/mL) in BALF. Standardized myrtol also attenuated LPS-induced MPO activity (from 0.82 ± 0.04 to 0.48 ± 0.06, U/g) and pathological changes (lung injury score: from 11.67 ± 0.33 to 7.83 ± 0.79) in the lung. Further study demonstrated that standardized myrtol prevented LPS-induced NF-κB activation in lung tissues.

DISCUSSION AND CONCLUSION

Together, these data suggest that standardized myrtol has the potential to protect against LPS-induced airway inflammation in a model of ALI.

Suppressive oligonucleotides inhibit inflammation in a murine model of mechanical ventilator induced lung injury

BACKGROUND

Mechanical ventilation (MV) is commonly used to improve blood oxygenation in critically ill patients and for general anesthesia. Yet the cyclic mechanical stress induced at even moderate ventilation volume settings [tidal volume (Vt) <10 mL/kg] can injure the lungs and induce an inflammatory response. This work explores the effect of treatment with suppressive oligonucleotides (Sup ODN) in a mouse model of ventilator-induced lung injury (VILI).

METHODS

Balb/cJ mice were mechanically ventilated for 4 h using clinically relevant Vt and a positive end-expiratory pressure of 3 cmH₂O under 2-3% isoflurane anesthesia. Lung tissue and bronchoalveolar lavage fluid were collected to assess lung inflammation and lung function was monitored using a FlexiVent^®.

RESULTS

MV induced significant pulmonary inflammation characterized by the influx and activation of CD11c⁺/F4/80⁺ macrophages and CD11b⁺/Ly6G⁺ polymorphonuclear cells into the lung and bronchoalveolar lavage fluid. The concurrent administration of Sup ODN attenuated pulmonary inflammation as evidenced by reduced cellular influx and production of inflammatory cytokines. Oligonucleotide treatment did not worsen lung function as measured by static compliance or resistance.

CONCLUSIONS

Treatment with Sup ODN reduces the lung injury induced by MV in mice.

Serum and exhaled breath condensate inflammatory cytokines in community-acquired pneumonia: a prospective cohort study

Background

The role and relationship between pro- and anti-inflammatory cytokines represents one of the least studied aspects of the pathogenesis of community-acquired pneumonia (CAP). The aim of the present study was to evaluate pro- and anti-inflammatory cytokines at both local (lung) and systemic (blood) levels and their relationship with the severity of the disease on admission and time for a patient to reach clinical stability during hospitalisation.

Methods

This was an observational, prospective, cohort study of hospitalised patients with a diagnosis of CAP at the IRCCS Policlinico Hospital, Milan, Italy, between April 2010 and January 2012. Ten pro-inflammatory cytokines (interleukin [IL]-1, IL-1α, IL-1β, IL-2, IL-6, IL-8, tumor necrosis factor [TNF]α and interferon [IFN]γ) and anti-inflammatory cytokines (IL-4 and IL-10) were measured in both serum and exhaled breath condensate within 24 h after hospital admission.

Results

A total of 74 patients (median age: 76 years; gender: 61 % male) were enrolled. The anti- to pro-inflammatory cytokine ratio was reduced in patients with severe disease on admission and prolonged time to reach clinical stability. This was due to lower levels of anti-inflammatory cytokines in the exhaled breath condensate and higher levels of pro-inflammatory cytokines in serum.

Conclusions

Dis-regulation between pro- and anti-inflammatory pathways might be a part of the pathogenic mechanisms that lead to severe infection and worse early clinical outcomes in CAP patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s41479-016-0009-7) contains supplementary material, which is available to authorized users.

The prognostic value of muscle regional oxygen saturation index in severe community-acquired pneumonia: a prospective observational study

Background

Community-acquired pneumonia (CAP) mortality exceeds 20 % in critical care patients despite appropriate antibiotic therapy. Regional tissue oxygen saturation index (rSO2) measured with near-infrared spectroscopy (NIRS) might facilitate early detection for patients at risk of serious complications. Our objectives were to determine the relationship between early determination of rSO2 and mortality and to compare discrimination power for mortality of rSO2 and other resuscitation variables in critically ill CAP patients.

Methods

This is a prospective observational study. Patients with CAP were enrolled within 6 h to intensive care admission. Demographics and clinical variables were recorded. rSO2 was determined using NIRS in brachioradialis muscle. All variables were determined at baseline and 24 h after admission.

Results

Forty patients were enrolled. Fourteen patients (35 %) had a baseline rSO2 < 60 % and 7 of them died (50 %). Only 1 of 26 (3.8 %) patients with rSO2 ≥ 60 % died (p = 0.007). The area under ROC curve (AUROC) showed consistent mortality discrimination at baseline (0.84, p = 0.03) and at 24 h (0.86, p = 0.006) for rSO2 values. Cox regression analysis showed that “low” rSO2 at ICU admission (hazard ratio (HR) = 8.99; 95 % confidence interval (CI) 1.05–76.8; p = 0.045) and “low” rSO2 at 24 h (HR = 13.18; 95 % CI 1.52–113.6; p = 0.019) were variables independently associated with mortality. In contrast, other variables such as Acute Physiology and Chronic Health Evaluation (APACHE II) score (HR = 1.09; 95 % CI 0.99–1.19; p = 0.052) were not associated with mortality.

Conclusions

Our findings suggest that forearm skeletal muscle rSO2 differs in patients with severe CAP according to outcome and might be an early prognosis tool.

Predictive value of plasma biomarkers for mortality and organ failure development in patients with acute respiratory distress syndrome

PURPOSE

To evaluate the predictive value of 6 different biomarkers in the development of multiple-organ failure (MOF) and mortality in a contemporary prospective cohort of acute respiratory distress syndrome (ARDS).

METHODS

Patients with ARDS admitted to a tertiary referral center during an 8-month period were included. Plasma sample collection of 6 different biomarkers on days 1, 3, and 5 after ARDS onset was performed (von Willebrand factor, thrombin-antithrombin III complex, plasminogen activator inhibitor 1, interleukin 8, receptor for advanced glycation end-products, and club cell secretory protein). Main outcomes included hospital mortality and development of MOF. Logistic regression models for MOF and mortality prediction were created including biomarkers levels and clinical predictors.

RESULTS

One hundred patients were included in the study. Do-not-resuscitate status and McCabe score were independently associated with increased mortality. None of the 6 biomarkers measured at the time of ARDS diagnosis predicted hospital mortality. After adjustment for important clinical characteristics, elevated day-1 interleukin 8 levels were associated with the development of MOF.

CONCLUSIONS

Addition of biomarkers did not improve mortality prediction in this cohort of ARDS. Association between elevated interleukin 8 levels and progression of organ failures suggests an important role of exaggerated inflammatory response in the development of MOF.

FK866, a visfatin inhibitor, protects against acute lung injury after intestinal ischemia-reperfusion in mice via NF-κB pathway

OBJECTIVE

To determine whether administration of FK866, a competitive inhibitor of visfatin, attenuates acute lung injury induced by intestinal ischemia-reperfusion (I/R).

BACKGROUND

Acute lung injury, a frequent complication of intestinal I/R, is an inflammatory disorder of the lung, which is characterized by an overproduction of proinflammatory cytokines and increased permeability of the alveolar-capillary barrier, resulting in multiple organ dysfunction. Therefore, the development of novel and effective therapies for intestinal I/R is critical for the improvement of patient outcome. Visfatin, a 54-kDa secretory protein, is known as a proinflammatory cytokine and plays a deleterious role in inflammatory diseases.

METHODS

Male C57BL/6J mice were subjected to intestinal I/R induced by occlusion of the superior mesenteric artery for 90 minutes, followed by reperfusion. During reperfusion period, mice were treated with vehicle or FK866 (10 mg/kg of body weight) by an intraperitoneal injection. The levels of visfatin, proinflammatory mediators, and other markers were assessed 4 hours after reperfusion. In addition, survival study was conducted in intestinal I/R mice with or without FK866 treatment.

RESULTS

Plasma and lung visfatin protein levels were significantly increased after intestinal I/R. FK866 treatment significantly attenuated intestinal and lung injury by inhibiting proinflammatory cytokine production, cellular apoptosis, and NF-κB activation, hence improving survival rate. In vitro studies showed that macrophages treated with lipopolysaccharides upregulated visfatin expression, whereas FK866 inhibited proinflammatory cytokine production via modulation of the NF-κB pathway.

CONCLUSIONS

Collectively, these findings implicate FK866 as a novel therapeutic compound for intestinal I/R-induced attenuates acute lung injury via modulation of innate immune functions.

Plasma biomarkers for acute respiratory distress syndrome: a systematic review and meta-analysis*

OBJECTIVE

Numerous studies have focused on biomarkers for acute lung injury and acute respiratory distress syndrome. Although several biomarkers have been identified, their relative performance is unclear. We aim to provide a quantitative overview of plasma-derived biomarkers associated with acute respiratory distress syndrome diagnosis or mortality.

DATA SOURCES

MEDLINE (inception to January 2012) and personal databases.

STUDY SELECTION

English-language studies on plasma biomarkers associated with acute respiratory distress syndrome diagnosis or mortality.

DATA EXTRACTION

Demographic variables, plasma levels of biomarker, statistical data, acute respiratory distress syndrome occurrence, and mortality rates were retrieved. The methodological quality was assessed with the Quality Assessment of Diagnostic Accuracy Studies score. Clinical outcomes included 1) diagnosis of acute respiratory distress syndrome in the at-risk population and 2) mortality in acute respiratory distress syndrome patients. For each biomarker, pooled odds ratios for clinical outcome were calculated by meta-analysis, and biomarkers were ranked according to pooled odds ratio.

DATA SYNTHESIS

Fifty-four studies appeared eligible for meta-analysis, together including 3,753 patients. We identified 20 biomarkers for diagnosis of acute respiratory distress syndrome in the at-risk population and 19 biomarkers for mortality of acute respiratory distress syndrome patients. The biomarkers most strongly associated with acute respiratory distress syndrome diagnosis in the at-risk population, when increased, were Krebs von den Lungen-6 (odds ratio [95% CI], 6.1 [3.0-12.1]), lactate dehydrogenase (5.7 [1.7-19.1]), soluble receptor for advanced glycation end products (3.5 [1.7-7.2]), and von Willebrand Factor (3.1 [2.0-5.2]). The biomarkers most strongly associated with acute respiratory distress syndrome mortality, when increased, were interleukin-4 (18.0 [6.0-54.2]), interleukin-2 (11.8 [4.3-32.2]), angiopoietin-2 (6.4 [1.3-30.4]), and Krebs von den Lungen-6 (5.1 [3.0-12.2]). Decreased levels of Protein C were associated with increased odds for acute respiratory distress syndrome diagnosis and mortality.

CONCLUSIONS

This meta-analysis provides a unique ranking of plasma biomarkers according to their strength of association with acute respiratory distress syndrome diagnosis or acute respiratory distress syndrome mortality. The relative performance of biomarkers among studies shown in this ranking may help to improve acute respiratory distress syndrome diagnosis and outcome prediction.

ICU-acquired pneumonia with or without etiologic diagnosis: a comparison of outcomes

OBJECTIVES

The impact of ICU-acquired pneumonia without etiologic diagnosis on patients' outcomes is largely unknown. We compared the clinical characteristics, inflammatory response, and outcomes between patients with and without microbiologically confirmed ICU-acquired pneumonia.

DESIGN

Prospective observational study.

SETTING

ICUs of a university teaching hospital.

PATIENTS

We prospectively collected 270 consecutive patients with ICU-acquired pneumonia. Patients were clustered according to positive or negative microbiologic results.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We compared the characteristics and outcomes between both groups. Negative microbiology was found in 82 patients (30%). Both groups had similar baseline severity scores. Patients with negative microbiology presented more frequently chronic renal failure (15 [18%] vs 11 [6%]; p=0.003), chronic heart disorders (35 [43%] vs 55 [29%]; p=0.044), less frequently previous intubation (44 [54%] vs 135 [72%]; p=0.006), more severe hypoxemia (PaO2/FIO2: 165±73 mm Hg vs 199±79 mm Hg; p=0.001), and shorter ICU stay before the onset of pneumonia (5±5 days vs 7±9 days; p=0.001) compared with patients with positive microbiology. The systemic inflammatory response was similar between both groups. Negative microbiology resulted in less changes of empiric treatment (33 [40%] vs 112 [60%]; p=0.005) and shorter total duration of antimicrobials (13±6 days vs 17±12 days; p=0.006) than positive microbiology. Following adjustment for potential confounders, patients with positive microbiology had higher hospital mortality (adjusted odds ratio 2.96, 95% confidence interval 1.24-7.04, p=0.014) and lower 90-day survival (adjusted hazard ratio 0.50, 95% confidence interval 0.27-0.94, p=0.031), with a nonsignificant lower 28-day survival.

CONCLUSIONS

Although the possible influence of previous intubation in mortality of both groups is not completely discarded, negative microbiologic findings in clinically suspected ICU-acquired pneumonia are associated with less frequent previous intubation, shorter duration of antimicrobial treatment, and better survival. Future studies should corroborate the presence of pneumonia in patients with suspected ICU-acquired pneumonia and negative microbiology.