Sepsis-related Acute Lung Injury Research Articles

APACHE III Outcome Prediction in Patients Admitted to the Intensive Care Unit with Sepsis Associated Acute Lung Injury.

Background and objectiveAcute Physiology and Chronic Health Evaluation (APACHE) III score has been widely used for prediction of clinical outcomes in mixed critically ill patients. However, it has not been validated in patients with sepsis-associated acute lung injury (ALI). The aim of the study was to explore the calibration and predictive value of APACHE III in patients with sepsis-associated ALI.MethodThe study was a secondary analysis of a prospective randomized controlled trial investigating the efficacy of rosuvastatin in sepsis-associated ALI (Statins for Acutely Injured Lungs from Sepsis, SAILS). The study population was sepsis-related ALI patients. The primary outcome of the current study was the same as in the original trial, 60-day in-hospital mortality, defined as death before hospital discharge, censored 60 days after enrollment. Discrimination of APACHE III was assessed by calculating the area under the receiver operating characteristic (ROC) curve (AUC) with its 95% CI. Hosmer-Lemeshow goodness-of-fit statistic was used to assess the calibration of APACHE III. The Brier score was reported to represent the overall performance of APACHE III in predicting outcome.Main resultsA total of 745 patients were included in the study, including 540 survivors and 205 non-survivors. Non-survivors were significantly older than survivors (59.71±16.17 vs 52.00±15.92 years, p<0.001). The primary causes of ALI were also different between survivors and non-survivors (p = 0.017). Survivors were more likely to have the cause of sepsis than non-survivors (21.2% vs. 15.1%). APACHE III score was higher in non-survivors than in survivors (106.72±27.30 vs. 88.42±26.86; p<0.001). Discrimination of APACHE III to predict mortality in ALI patients was moderate with an AUC of 0.68 (95% confidence interval: 0.64–0.73).Conclusionthis study for the first time validated the discrimination of APACHE III in sepsis associated ALI patients. The result shows that APACHE III score has moderate predictive value for in-hospital mortality among adults with sepsis-associated acute lung injury.

Kallistatin protects against sepsis-related acute lung injury via inhibiting inflammation and apoptosis.

Kallistatin, an endogenous plasma protein, exhibits pleiotropic properties in inhibiting inflammation, oxidative stress and apoptosis, as evidenced in various animal models and cultured cells. Here, we demonstrate that kallistatin levels were positively correlated with the concentration of total protein in bronchoalveolar lavage fluids (BALF) from patients with sepsis-related acute respiratory distress syndrome (ARDS), indicating a compensatory mechanism. Lower ratio of kallistatin to total protein in BALF showed a significant trend toward elevated neutrophil counts (P = 0.002) in BALF and increased mortality (P = 0.046). In lipopolysaccharide (LPS)-treated mice, expression of human kallistatin in lung by gene transfer with human kallistatin-encoding plasmid ameliorated acute lung injury (ALI) and reduced cytokine/chemokine levels in BALF. These mice exhibited attenuated lung epithelial apoptosis and decreased Fas/FasL expression compared to the control mice. Mouse survival was improved by kallistatin gene transfer or recombinant human kallistatin treatment after LPS challenge. In LPS-stimulated A549 human lung epithelial cells, kallistatin attenuated apoptosis, down-regulated Fas/FasL signaling, suppressed intracellular reactive oxygen species (ROS) and inhibited ROS-mediated NF-κB activation and inflammation. Furthermore, LPS-induced apoptosis was blocked by antioxidant N-acetylcysteine or NF-κB inhibitor via down-regulating Fas expression. These findings suggest the therapeutic potential of kallistatin for sepsis-related ALI/ARDS.

Oroxylin-A Rescues LPS-Induced Acute Lung Injury via Regulation of NF-κB Signaling Pathway in Rodents

Background and PurposeSuccessful drug treatment for sepsis-related acute lung injury (ALI) remains a major clinical problem. This study was designed to assess the beneficial effects of post-treatment of oroxylin A (OroA), a flavonoid, in ameliorating lipopolysaccharides (LPS)-induced lung inflammation and fatality.Experimental ApproachRats were injected with LPS (10 mg/kg, iv) to induce ALI, and OroA was given (15 mg/kg, iv) 1 hr or 6 hrs after LPS challenge. Twenty four hrs after LPS challenge, biochemical changes in the blood and lung tissues, and morphological/histological alterations in the lung associated with inflammation and injury were examined. Therapeutic effect of OroA was assessed by measuring the survival rate in endotoxemic mice.Key ResultsLPS (10 mg/kg, iv) significantly altered WBC counts, elevated plasma tumor necrosis factor (TNF)-α and nitric oxide (NO), increased pulmonary edema, thickened alveolar septa, and decreased survival rate. These changes were ameliorated by OroA (15 mg/kg, iv) administered 1 hr or 6 hrs after LPS challenge. This post-treatment also significantly attenuated LPS-induced activation of nuclear factor-κB (NF-κB) and the release of high mobility group box 1 (HMGB1) in lung tissues. Furthermore, post-treatment with OroA (60 mg/kg, ip) administered 1 hr or 6 hrs after LPS challenge in mice significantly increased survival rate.Conclusion and ImplicationOroA administered after induction of ALI by LPS significantly prevent and revere lung tissues injuries with increased survival rate. Positive post-treatment effects of OroA suggest that OroA is a potentially useful candidate for managing lung inflammation in LPS-induced endotoxemia and septic shock.

Short women with severe sepsis-related acute lung injury receive lung protective ventilation less frequently: an observational cohort study

IntroductionLung protective ventilation (LPV) has been shown to improve survival and the duration of mechanical ventilation in acute lung injury (ALI) patients. Mortality of ALI may vary by gender, which could result from treatment variability. Whether gender is associated with the use of LPV is not known.MethodsA total of 421 severe sepsis-related ALI subjects in the Consortium to Evaluate Lung Edema Genetics from seven teaching hospitals between 2002 and 2008 were included in our study. We evaluated patients' tidal volume, plateau pressure and arterial pH to determine whether patients received LPV during the first two days after developing ALI. The odds ratio of receiving LPV was estimated by a logistic regression model with robust and cluster options.ResultsWomen had similar characteristics as men with the exception of lower height and higher illness severity, as measured by Acute Physiology and Chronic Health Evaluation (APACHE) II score. 225 (53%) of the subjects received LPV during the first two days after ALI onset; women received LPV less frequently than men (46% versus 59%, P < 0.001). However, after adjustment for height and severity of illness (APACHE II), there was no difference in exposure to LPV between men and women (P = 0.262).ConclusionsShort people are less likely to receive LPV, which seems to explain the tendency of clinicians to adhere to LPV less strictly in women. Strategies to standardize application of LPV, independent of differences in height and severity of illness, are necessary.

Reduction of sCD40L In Transfusable Plasma: A Potential TRALI Mitigation Strategy

AbstractAbstract 664 Background:Soluble CD40 ligand (sCD40L) rapidly translocates to the surface of activated platelets and plays a role in the inflammatory cascade. sCD40L has been shown to not only accumulate during the storage period of platelets, but has also been linked with TRALI and febrile reactions following platelet transfusions. Licensed plasma has significant platelet contamination which introduces platelet-derived inflammatory proteins into the plasma. Blood components containing greater than 30 ml of plasma have the highest rate of transfusion-associated complications, most notably TRALI. Both centrifugation at 12,500g as well as leukofiltration are capable of decreasing platelet levels in plasma by 2 logs. We hypothesize that pre-storage platelet reduction will decrease the accumulation of sCD40L in licensed plasma, which will reduce the pro-inflammatory potential of thawed plasma, and abate neutrophil (PMN) priming in vitro. Methods:Plasma preparation. Units of whole blood were collected from healthy human donors. Control units were prepared in accordance with AABB standards. For units undergoing cell depletion centrifugation (CDC), following the primary separation from the red cells, the plasma was centrifuged at an additional 12,500g for 7 minutes at 4°C. For leukofiltration, whole blood was filtered using Pall Corporation (Port Washington, NY), MacoPharma (Mouvaux, France), and Terumo (Elkton, MD) filters per the manufacturers' specifications. The plasma was then separated and frozen per AABB standards. Plasma samples were thawed in a 37°C shaking water bath and then stored at 4°C for 5 days. Levels of sCD40L were measured on days 1, 3, and 5 post-thaw using a commercial ELISA kit (R&D Systems). PMN isolation & priming. Heparinized whole blood was drawn from healthy human donors, and PMNs were then isolated by standard techniques: dextran sedimentation, Ficoll-Hypaque gradient centrifugation, and hypotonic lysis. PMNs were incubated with 10% plasma at 37°C for 5 minutes and then activated with 1 μM formyl-Met-Leu-Phe (fMLP), and the rate of O2− production was measured via the reduction of cytochrome c at 550 nm. Priming activity is the augmentation of the fMLP-activated respiratory burst (nmol O2−/min). Results:Control plasma showed a significant increase in sCD40L concentration and PMN priming activity over the 5 day storage period (Figure 1). Both CDC and pre-storage whole blood leukofiltration decreased sCD40L concentration vs. controls (Table 1). There were no significant increases in sCD40L in leukofiltered plasma over 5 days of storage. There was no increased priming activity over the 5 days of storage in CDC and leukofiltered units. [Display omitted] Conclusion:sCD40L plays an important role in inflammation and its inhibition decreases sepsis-related acute lung injury (ALI) in animal models. Platelet contamination and resultant high levels of sCD40L are associated with increased PMN priming activity in vitro over the storage period of thawed plasma and may be contributing to TRALI risk. The reduction of platelet contamination in frozen plasma may be a valuable TRALI mitigation strategy in the production of licensed plasma. Disclosures:Bercovitz:National Blood Foundation: Research Funding.

Plasma granulocyte colony-stimulating factor levels correlate with clinical outcomes in patients with acute lung injury.

To evaluate the association between plasma granulocyte colony-stimulating factor (G-CSF) levels and clinical outcomes including mortality in patients with acute lung injury (ALI), and to determine whether lower tidal volume ventilation was associated with a more rapid decrease in plasma G-CSF over time in patients with ALI. Retrospective measurement of G-CSF levels in plasma samples that were collected prospectively as part of a large multicenter clinical trial. Intensive care units in ten university centers. The study included 645 patients enrolled in the National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome Clinical Network trial of lower tidal volumes compared with traditional tidal volumes for ALI. Baseline plasma levels of G-CSF were associated with an increased risk of death and a decrease in ventilator-free days and organ failure-free days in multivariate analyses controlling for ventilation strategy, age, and sex (Odds ratio death 1.2/log10 increment G-CSF, 95% confidence interval 1.01 to 1.4). Stratification of G-CSF levels into quartiles revealed a strong association between the highest levels of G-CSF and an increased risk of death and decreased ventilator-free days and organ failure-free days in multivariate analyses controlling for ventilation strategy, Acute Physiology and Chronic Health Evaluation III score, Pao2/Fio2 ratio, creatinine, and platelet count (p < 0.05). Subgroup multivariate analysis of patients with sepsis as their risk factor for ALI revealed a U-shaped association between mortality and G-CSF levels such that risk increased linearly from the second through fourth (highest) quartiles, yet also increased in the first (lowest) quartile. G-CSF levels decreased over time in both tidal volume groups, and there was no statistical difference in the extent of decrease between ventilator strategies. In patients with ALI, plasma G-CSF levels are associated with morbidity and mortality, but these levels are not influenced by tidal volume strategy. In patients with sepsis-related ALI, a bimodal association between baseline plasma G-CSF levels and subsequent morbidity and mortality from this disease was found.

Mobilization and Margination of Bone Marrow Gr-1high Monocytes during Subclinical Endotoxemia Predisposes the Lungs toward Acute Injury

The specialized role of mouse Gr-1(high) monocytes in local inflammatory reactions has been well documented, but the trafficking and responsiveness of this subset during systemic inflammation and their contribution to sepsis-related organ injury has not been investigated. Using flow cytometry, we studied monocyte subset margination to the pulmonary microcirculation during subclinical endotoxemia in mice and investigated whether marginated monocytes contribute to lung injury in response to further septic stimuli. Subclinical low-dose i.v. LPS induced a rapid (within 2 h), large-scale mobilization of bone marrow Gr-1high monocytes and their prolonged margination to the lungs. With secondary LPS challenge, membrane TNF expression on these premarginated monocytes substantially increased, indicating their functional priming in vivo. Zymosan challenge produced small increases in pulmonary vascular permeability, which were markedly enhanced by the preadministration of low-dose LPS. The LPS-zymosan-induced permeability increases were effectively abrogated by pretreatment (30 min before zymosan challenge) with the platelet-activating factor antagonist WEB 2086 in combination with the phosphatidylcholine-phospholipase C inhibitor D609, suggesting the involvement of platelet-activating factor/ceramide-mediated pathways in this model. Depletion of monocytes (at 18 h after clodronate-liposome treatment) significantly attenuated the LPS-zymosan-induced permeability increase. However, restoration of normal LPS-induced Gr-1high monocyte margination to the lungs (at 48 h after clodronate-liposome treatment) resulted in the loss of this protective effect. These results demonstrate that mobilization and margination of Gr-1high monocytes during subclinical endotoxemia primes the lungs toward further septic stimuli and suggest a central role for this monocyte subset in the development of sepsis-related acute lung injury.

DEVELOPMENT OF BRONCHUS-ASSOCIATED LYMPHOID TISSUE HYPERPLASIA FOLLOWING LIPOPOLYSACCHARIDE-INDUCED LUNG INFLAMMATION IN RATS

Gram-negative bacterial endotoxin lipopolysaccharide (LPS) administration has been used as an animal model of sepsis-related acute lung injury and adult respiratory distress syndrome (ALI/ARDS). This paper describes the lung histology following lung injury induced by the intraperitoneal (i.p.) administration of endotoxin to rats, in comparison with earlier findings. ALI was induced by the i.p. administration of Esherichia coli LPS 2 (n = 8) or 3 (n = 5) mg/kg, whereas physiological saline was administered to the control animals (n = 5). Eighteen hours after the LPS injections, the animals were euthanized. The lungs and heart were removed in one block for histological study (hematoxylin and eosin [H&E], periodic acid–Schiff [PAS], Mason's trichrome; light microscopy). The lung tissue injury (bronchial wall, vessels, alveoli, interstitium) was graded via a scoring system (0 to 3+). The control animals showed intact lung tissue. Ten of the 13 LPS group had bronchus-associated lymphoid tissue (BALT) hyperplasia. Pathological signs of ALI/ARDS, diffuse alveolar damage (DAD) and emphysema, were observed in 5 and 8 cases, respectively. LPS injection induces primarily BALT hyperplasia and also the less characteristic DAD. This rat model is suitable for the investigation not only of ALI/ARDS but also of BALT hyperplasia occurring as a consequence of chronic pulmonary inflammatory processes.

Variation in the myosin light chain kinase gene is associated with development of acute lung injury after major trauma*

Single nucleotide polymorphisms in the myosin light chain kinase (MYLK) gene have been implicated in the risk of sepsis-related acute lung injury and asthma. MYLK encodes protein isoforms involved in multiple components of the inflammatory response, including apoptosis, vascular permeability, and leukocyte diapedesis. We tested the association of MYLK gene variation in the development of acute lung injury in major trauma patients. We conducted a prospective cohort study of 273 subjects with major trauma (injury severity score > or = 16). All x-rays and clinical data were reviewed by three clinicians for acute lung injury classification. A total of 17 tagging single nucleotide polymorphisms in MYLK were genotyped. Single nucleotide polymorphisms were individually assessed at the genotype level, and multiple logistic regression models were used to adjust for baseline variables. Haplotype analyses of sliding windows including 2-5 single nucleotide polymorphisms were conducted. Ninety-one of the 273 subjects (33%) met criteria for acute lung injury within 5 days of traumatic insult. Three informative MYLK coding single nucleotide polymorphisms were individually associated with acute lung injury, with two informative risk-conferring genotypes His21Pro (CC genotype, odds ratio = 1.87, 95% confidence interval 1.06-3.33; p = 0.022) and Pro147Ser (TT, odds ratio = 2.13, 95% confidence interval 1.14-4.10; p = 0.011) more frequent than the noninformative Thr335Thr CC genotype (odds ratio = 0.42, 95% confidence interval 0.20-0.85; p = 0.010). Each of these genotypic associations was more pronounced in African Americans with trauma. Multivariate analyses demonstrated the association of each MYLK single nucleotide polymorphism with acute lung injury to be independent of age, injury severity score, Acute Physiology and Chronic Health Evaluation III, and the mechanism of trauma. Finally, haplotype analyses revealed strong acute lung injury associations with 2-4 single nucleotide polymorphism haplotypes, all involving His21Pro (p < 0.008). Three MYLK coding single nucleotide polymorphisms previously associated with sepsis-induced acute lung injury and severe asthma in African Americans were associated with acute lung injury development after trauma in African Americans, although effect directions differed. These results confirm our prior studies implicating MYLK as a susceptibility gene in a distinct acute lung injury subset other than sepsis.

Toll-like Receptor 1 Polymorphisms Affect Innate Immune Responses and Outcomes in Sepsis

Polymorphisms affecting Toll-like receptor (TLR)-mediated responses could predispose to excessive inflammation during an infection and contribute to an increased risk for poor outcomes in patients with sepsis. To identify hypermorphic polymorphisms causing elevated TLR-mediated innate immune cytokine and chemokine responses and to test whether these polymorphisms are associated with increased susceptibility to death, organ dysfunction, and infections in patients with sepsis. We screened single-nucleotide polymorphisms (SNPs) in 43 TLR-related genes to identify variants affecting TLR-mediated inflammatory responses in blood from healthy volunteers ex vivo. The SNP associated most strongly with hypermorphic responses was tested for associations with death, organ dysfunction, and type of infection in two studies: a nested case-control study in a cohort of intensive care unit patients with sepsis, and a case-control study using patients with sepsis, patients with sepsis-related acute lung injury, and healthy control subjects. The SNP demonstrating the most hypermorphic effect was the G allele of TLR1(-7202A/G) (rs5743551), which associated with elevated TLR1-mediated cytokine production (P < 2 x 10(-20)). TLR1(-7202G) marked a coding SNP that causes higher TLR1-induced NF-kappaB activation and higher cell surface TLR1 expression. In the cohort of patients with sepsis TLR1(-7202G) predicted worse organ dysfunction and death (odds ratio, 1.82; 95% confidence interval, 1.07-3.09). In the case-control study TLR1(-7202G) was associated with sepsis-related acute lung injury (odds ratio, 3.40; 95% confidence interval, 1.59-7.27). TLR1(-7202G) also associated with a higher prevalence of gram-positive cultures in both clinical studies. Hypermorphic genetic variation in TLR1 is associated with increased susceptibility to organ dysfunction, death, and gram-positive infection in sepsis.

Tezosentan counteracts endotoxin-induced pulmonary edema and improves gas exchange.

Sepsis-induced acute lung injury is still associated with high morbidity and mortality. The pathophysiology is complex, and markers of injury include increased extravascular lung water. To evaluate the effects of the novel dual endothelin receptor antagonist tezosentan on endotoxin-induced changes in extravascular lung water and gas exchange, 16 pigs were anaesthetized and catheterized. Twelve animals were subjected to 5 h of endotoxemia. After 2 h, six of these animals received a bolus of tezosentan 1 mg kg(-1) followed by a continuous infusion of 1 mg kg(-1) h(-1) to the end of the experiment at 5 h. Conventional pulmonary and hemodynamic parameters were measured. Extravascular lung water was determined in these pigs after 5 h of endotoxemia, as well as in the four additional nonendotoxemic sham animals. Tezosentan in the current dosage counteracted the deterioration of lung function caused by endotoxin, as measured by dead space, venous admixture, and compliance. In addition, pulmonary hypertension was attenuated. Tezosentan had a marked effect on the endotoxin-induced increase in extravascular lung water that was reduced to levels observed in nonendotoxemic sham animals. These results suggest that endothelin is involved in endotoxin-induced lung injury and the development of pulmonary edema. Dual endothelin receptor antagonism may be of value in the treatment of sepsis-related acute lung injury.

Effects of positive-pressure ventilatory frequency on hepatic blood flow and performance

The liver metabolizes several mediators of sepsis-related acute lung injury, but is frequently dysfunctional during intermittent positive-pressure ventilation (IPPV). With IPPV, increases in intrathoracic pressure (ITP) phasically increase the effective hepatic back pressure owing to compression by the diaphragm and retrograde propagation of swings in right atrial pressure. If intrahepatic flow distribution or the time constant of hepatic outflow are accordingly altered by ventilatory frequency (f), then hepatic performance may be compromised beyond a critical f threshold. In two canine models, we characterized at constant mean ITP the effects of ITP pulses on hepatic blood flow partitioning and performance over a f spectrum (0.4, 1.67, and 2.5 Hz) during IPPV and high-frequency jet ventilation. Portal venous flow (Qpv) and hepatic arterial flow (Qha) were measured by electromagnetic flow probes and performance by the pharmacokinetics of infused indocyanine green (0.25 mg/kg). To assess pressure wave transmission to the portal vein, cardiac cycle-specific (CCS) ITP pulses were used to alter the hepatic venous pressure (Phv) waveform. Measurements were made during control conditions, after graded acute hypovolemia (group 1, n = 7,20 mL/kg bleed; group 2, n = 6, bled to a mean aortic pressure of 45 mm Hg) to change the hepatic critical pressure balance, and after blood reinfusion. Despite decreases in peak-inspiratory transpulmonary pressure with increasing f, phasic reductions in Qpv and the transmural portal venous pressure (Ppv) to Phv gradient were similar at all f. The inspiratory Ppv waveform reflected changes in abdominal pressure, and was not altered by differential swings in Phv with CCS ITP pulses regardless of hypovolemia. We conclude that at f ≤ 2.5 Hz, phasic increases in ITP modulate the hepatic outflow pressure in a post-sinusoidal flow-limiting segment in which diaphragmatic compression increases resistance to Qpv in a f-dependent manner. However, the pharmacokinetics of substances having similar hepatic extraction will primarily vary with inflow over this f spectrum.

Chromobacterium prodigiosum

The specialized role of mouse Gr-1^high monocytes in local inflammatory reactions has been well documented, but the trafficking and responsiveness of this subset during systemic inflammation and their contribution to sepsis-related organ injury has not been investigated. Using flow cytometry, we studied monocyte subset margination to the pulmonary microcirculation during subclinical endotoxemia in mice and investigated whether marginated monocytes contribute to lung injury in response to further septic stimuli. Subclinical low-dose i.v. LPS induced a rapid (within 2 h), large-scale mobilization of bone marrow Gr-1^high monocytes and their prolonged margination to the lungs. With secondary LPS challenge, membrane TNF expression on these premarginated monocytes substantially increased, indicating their functional priming in vivo. Zymosan challenge produced small increases in pulmonary vascular permeability, which were markedly enhanced by the preadministration of low-dose LPS. The LPS-zymosan-induced permeability increases were effectively abrogated by pretreatment (30 min before zymosan challenge) with the platelet-activating factor antagonist WEB 2086 in combination with the phosphatidylcholine-phospholipase C inhibitor D609, suggesting the involvement of platelet-activating factor/ceramide-mediated pathways in this model. Depletion of monocytes (at 18 h after clodronate-liposome treatment) significantly attenuated the LPS-zymosan-induced permeability increase. However, restoration of normal LPS-induced Gr-1^high monocyte margination to the lungs (at 48 h after clodronate-liposome treatment) resulted in the loss of this protective effect. These results demonstrate that mobilization and margination of Gr-1^high monocytes during subclinical endotoxemia primes the lungs toward further septic stimuli and suggest a central role for this monocyte subset in the development of sepsis-related acute lung injury.