Murali Shyamsundar

Simvastatin decreases lipopolysaccharide-induced pulmonary inflammation in healthy volunteers.

RATIONALE Simvastatin inhibits inflammatory responses in vitro and in murine models of lung inflammation in vivo. As simvastatin modulates a number of the underlying processes described in acute lung injury (ALI), it may be a potential therapeutic option. OBJECTIVES To investigate in vivo if simvastatin modulates mechanisms important in the development of ALI in a model of acute lung inflammation induced by inhalation of lipopolysaccharide (LPS) in healthy human volunteers. METHODS Thirty healthy subjects were enrolled in a double-blind, placebo-controlled study. Subjects were randomized to receive 40 mg or 80 mg of simvastatin or placebo (n = 10/group) for 4 days before inhalation of 50 microg LPS. Measurements were performed in bronchoalveolar lavage fluid (BALF) obtained at 6 hours and plasma obtained at 24 hours after LPS challenge. Nuclear translocation of nuclear factor-kappaB (NF-kappaB) was measured in monocyte-derived macrophages. MEASUREMENTS AND MAIN RESULTS Pretreatment with simvastatin reduced LPS-induced BALF neutrophilia, myeloperoxidase, tumor necrosis factor-alpha, matrix metalloproteinases 7, 8, and 9, and C-reactive protein (CRP) as well as plasma CRP (all P < 0.05 vs. placebo). There was no significant difference between simvastatin 40 mg and 80 mg. BALF from subjects post-LPS inhalation induced a threefold up-regulation in nuclear NF-kappaB in monocyte-derived macrophages (P < 0.001); pretreatment with simvastatin reduced this by 35% (P < 0.001). CONCLUSIONS Simvastatin has antiinflammatory effects in the pulmonary and systemic compartment in humans exposed to inhaled LPS.

A randomized clinical trial of hydroxymethylglutaryl- coenzyme a reductase inhibition for acute lung injury (The HARP Study).

RATIONALE There is no effective pharmacological treatment for acute lung injury (ALI). Statins are a potential new therapy because they modify many of the underlying processes important in ALI. OBJECTIVES To test whether simvastatin improves physiological and biological outcomes in ALI. METHODS We conducted a randomized, double-blinded, placebo-controlled trial in patients with ALI. Patients received 80 mg simvastatin or placebo until cessation of mechanical ventilation or up to 14 days. Extravascular lung water was measured using thermodilution. Measures of pulmonary and nonpulmonary organ function were assessed daily. Pulmonary and systemic inflammation was assessed by bronchoalveolar lavage fluid and plasma cytokines. Systemic inflammation was also measured by plasma C-reactive protein. MEASUREMENTS AND MAIN RESULTS Sixty patients were recruited. Baseline characteristics, including demographics and severity of illness scores, were similar in both groups. At Day 7, there was no difference in extravascular lung water. By Day 14, the simvastatin-treated group had improvements in nonpulmonary organ dysfunction. Oxygenation and respiratory mechanics improved, although these parameters failed to reach statistical significance. Intensive care unit mortality was 30% in both groups. Simvastatin was well tolerated, with no increase in adverse events. Simvastatin decreased bronchoalveolar lavage IL-8 by 2.5-fold (P = 0.04). Plasma C-reactive protein decreased in both groups but failed to achieve significance in the placebo-treated group. CONCLUSIONS Treatment with simvastatin appears to be safe and may be associated with an improvement in organ dysfunction in ALI. These clinical effects may be mediated by a reduction in pulmonary and systemic inflammation. Clinical trial registered with www.controlled-trials.com (ISRCTN70127774).

Extravascular lung water indexed to predicted body weight is a novel predictor of intensive care unit mortality in patients with acute lung injury

Objectives:Acute lung injury and the acute respiratory distress syndrome are characterized by noncardiogenic pulmonary edema, which can be assessed by measurement of extravascular lung water. Traditionally, extravascular lung water has been indexed to actual body weight (mL/kg). Because lung size is dependent on height rather than weight, we hypothesized indexing to predicted body weight may be a better predictor of mortality in acute lung injury/acute respiratory distress syndrome. Design:Prospective observational cohort study. Setting:A tertiary referral intensive care unit. Patients:Patients were recruited within 48 hrs of fulfilling the American European Consensus Conference definition of acute lung injury/acute respiratory distress syndrome. Interventions:None. Measurements and Main Results:Demographics, severity of illness scores, and respiratory parameters were collected. Extravascular lung water was measured using the PiCCO system. This was indexed to actual and predicted body weight. Statistically significant predictors of mortality identified using single regressor logistic regression and additional variables known to be associated with outcome were entered into a multiple logistic regression analysis. Receiver operator characteristic curves were generated. Forty-four patients were recruited (septic 34%). Using single regressor logistic regression, six variables were statistically significantly related to mortality: Acute Physiology and Chronic Health Evaluation II, PaO2, PaO2/Fio2 ratio, oxygenation index, actual extravascular lung water, and predicted extravascular lung water. In multiple logistic regression analysis, predicted extravascular lung water but not actual extravascular lung water was a predictor of mortality with an odds ratio of 4.3 (95% confidence interval, 1.5–12.9) per sd. Although the area under the curve for predicted extravascular lung water (0.8; confidence interval, 0.65–0.94) was larger than for actual extravascular lung water (0.72; confidence interval, 0.53–0.91), this was not statistically significant (p = .12). A baseline predicted extravascular lung water value of 16 mL/kg predicted intensive care unit mortality with a sensitivity of 0.75 (confidence interval, 0.47–0.91) and specificity of 0.78 (confidence interval, 0.61–0.89). Conclusions:Early measurement of predicted extravascular lung water is a better predictor than actual extravascular lung water to identify patients at risk for death in acute lung injury/acute respiratory distress syndrome.

Keratinocyte Growth Factor Promotes Epithelial Survival and Resolution in a Human Model of Lung Injury

RATIONALE Increasing epithelial repair and regeneration may hasten resolution of lung injury in patients with the acute respiratory distress syndrome (ARDS). In animal models of ARDS, keratinocyte growth factor (KGF) reduces injury and increases epithelial proliferation and repair. The effect of KGF in the human alveolus is unknown. OBJECTIVES To test whether KGF can attenuate alveolar injury in a human model of ARDS. METHODS Volunteers were randomized to intravenous KGF (60 μg/kg) or placebo for 3 days, before inhaling 50 μg LPS. Six hours later, subjects underwent bronchoalveolar lavage (BAL) to quantify markers of alveolar inflammation and cell-specific injury. MEASUREMENTS AND MAIN RESULTS KGF did not alter leukocyte infiltration or markers of permeability in response to LPS. KGF increased BAL concentrations of surfactant protein D, matrix metalloproteinase (MMP)-9, IL-1Ra, granulocyte-macrophage colony-stimulating factor (GM-CSF), and C-reactive protein. In vitro, BAL fluid from KGF-treated subjects inhibited pulmonary fibroblast proliferation, but increased alveolar epithelial proliferation. Active MMP-9 increased alveolar epithelial wound repair. Finally, BAL from the KGF-pretreated group enhanced macrophage phagocytic uptake of apoptotic epithelial cells and bacteria compared with BAL from the placebo-treated group. This effect was blocked by inhibiting activation of the GM-CSF receptor. CONCLUSIONS KGF treatment increases BAL surfactant protein D, a marker of type II alveolar epithelial cell proliferation in a human model of acute lung injury. Additionally, KGF increases alveolar concentrations of the antiinflammatory cytokine IL-1Ra, and mediators that drive epithelial repair (MMP-9) and enhance macrophage clearance of dead cells and bacteria (GM-CSF). Clinical trial registered with ISRCTN 98813895.

Effect of simvastatin on physiological and biological outcomes in patients undergoing esophagectomy: a randomized placebo-controlled trial.

Objective:To test whether simvastatin improves physiological and biological outcomes in patients undergoing esophagectomy. Background:One-lung ventilation during esophagectomy is associated with inflammation, alveolar epithelial and systemic endothelial injury, and the development of acute lung injury (ALI). Statins that modify many of the underlying processes are a potential therapy to prevent ALI. Methods:We conducted a randomized double-blind placebo-controlled trial in patients undergoing esophagectomy. Patients received simvastatin 80 mg or placebo enterally for 4 days preoperatively and 7 days postoperatively. The primary end point was pulmonary dead space (Vd/Vt) at 6 hours after esophagectomy or before extubation. Inflammation was assessed by plasma cytokines and intraoperative exhaled breath condensate pH; alveolar type 1 epithelial injury was assessed by plasma receptor for advanced glycation end products and systemic endothelial injury by the urine albumin–creatinine ratio. Results:Thirty-nine patients were randomized; 8 patients did not undergo surgery and were excluded. Fifteen patients received simvastatin and 16 received placebo. There was no difference in Vd/Vt or other physiological outcomes. Simvastatin resulted in a significant decrease in plasma MCP-1 on day 3 and reduced exhaled breath condensate acidification. Plasma receptor for advanced glycation end products was significantly lower in the simvastatin-treated group, as was the urine albumin–creatinine ratio on day 7 postsurgery. ALI developed in 4 patients in the placebo group and no patients in the simvastatin group although this difference was not statistically significant (P = 0.1). Conclusions:In this proof of concept study, pretreatment with simvastatin in esophagectomy decreased biomarkers of inflammation as well as pulmonary epithelial and systemic endothelial injury.

Aspirin as a potential treatment in sepsis or acute respiratory distress syndrome

Sepsis is a common condition that is associated with significant morbidity, mortality and health-care cost. Pulmonary and non-pulmonary sepsis are common causes of the acute respiratory distress syndrome (ARDS). The mortality from ARDS remains high despite protective lung ventilation, and currently there are no specific pharmacotherapies to treat sepsis or ARDS. Sepsis and ARDS are characterised by activation of the inflammatory cascade. Although there is much focus on the study of the dysregulated inflammation and its suppression, the associated activation of the haemostatic system has been largely ignored until recently. There has been extensive interest in the role that platelet activation can have in the inflammatory response through induction, aggregation and activation of leucocytes and other platelets. Aspirin can modulate multiple pathogenic mechanisms implicated in the development of multiple organ dysfunction in sepsis and ARDS. This review will discuss the role of the platelet, the mechanisms of action of aspirin in sepsis and ARDS, and aspirin as a potential therapy in treating sepsis and ARDS.

Impaired endothelium-dependent vasodilatation is a novel predictor of mortality in intensive care

Objective:Endothelial function may be impaired in critical illness. We hypothesized that impaired endothelium-dependent vasodilatation is a predictor of mortality in critically ill patients. Design:Prospective observational cohort study. Setting:Seventeen-bed adult intensive care unit in a tertiary referral university teaching hospital. Patients:Patients were recruited within 24 hrs of admission to the intensive care unit. Interventions:The SphygmoCor Mx system was used to derive the aortic augmentation index from radial artery pulse pressure waveforms. Endothelium-dependent vasodilatation was calculated as the change in augmentation index in response to an endothelium-dependent vasodilator (salbutamol). Measurements and Main Results:Demographics, severity of illness scores, and physiological parameters were collected. Statistically significant predictors of mortality identified using single regressor analysis were entered into a multiple logistic regression model. Receiver operator characteristic curves were generated. Ninety-four patients completed the study. There were 80 survivors and 14 nonsurvivors. The Simplified Acute Physiology Score II, the Sequential Organ Failure Assessment score, leukocyte count, and endothelium-dependent vasodilatation conferred an increased risk of mortality. In logistic regression analysis, endothelium-dependent vasodilatation was the only predictor of mortality with an adjusted odds ratio of 26.1 (95% confidence interval [CI], 4.3–159.5). An endothelium-dependent vasodilatation value of 0.5% or less predicted intensive care unit mortality with a sensitivity of 79% (CI, 59–88%) and specificity of 98% (CI, 94–99%). Conclusions:In vivo bedside assessment of endothelium-dependent vasodilatation is an independent predictor of mortality in the critically ill. We have shown it to be superior to other validated severity of illness scores with high sensitivity and specificity.

Cigarette smokers have exaggerated alveolar barrier disruption in response to lipopolysaccharide inhalation

Rationale Cigarette smoke exposure is associated with an increased risk of the acute respiratory distress syndrome (ARDS); however, the mechanisms underlying this relationship remain largely unknown. Objective To assess pathways of lung injury and inflammation in smokers and non-smokers with and without lipopolysaccharide (LPS) inhalation using established biomarkers. Methods We measured plasma and bronchoalveolar lavage (BAL) biomarkers of inflammation and lung injury in smokers and non-smokers in two distinct cohorts of healthy volunteers, one unstimulated (n=20) and one undergoing 50 μg LPS inhalation (n=30). Measurements and main results After LPS inhalation, cigarette smokers had increased alveolar-capillary membrane permeability as measured by BAL total protein, compared with non-smokers (median 274 vs 208 μg/mL, p=0.04). Smokers had exaggerated inflammation compared with non-smokers, with increased BAL interleukin-1β (p=0.002), neutrophils (p=0.02), plasma interleukin-8 (p=0.003), and plasma matrix metalloproteinase-8 (p=0.006). Alveolar epithelial injury after LPS was more severe in smokers than non-smokers, with increased plasma (p=0.04) and decreased BAL (p=0.02) surfactant protein D. Finally, smokers had decreased BAL vascular endothelial growth factor (VEGF) (p<0.0001) with increased soluble VEGF receptor-1 (p=0.0001). Conclusions Cigarette smoke exposure may predispose to ARDS through an abnormal response to a ‘second hit,’ with increased alveolar-capillary membrane permeability, exaggerated inflammation, increased epithelial injury and endothelial dysfunction. LPS inhalation may serve as a useful experimental model for evaluation of the acute pulmonary effects of existing and new tobacco products.

Simvastatin decreases the level of heparin-binding protein in patients with acute lung injury

BackgroundHeparin-binding protein is released by neutrophils during inflammation and disrupts the integrity of the alveolar and capillary endothelial barrier implicated in the development of acute lung injury and systemic organ failure. We sought to investigate whether oral administration of simvastatin to patients with acute lung injury reduces plasma heparin-binding protein levels and improves intensive care unit outcome.MethodsBlood samples were collected from patients with acute lung injury with 48 h of onset of acute lung injury (day 0), day 3, and day 7. Patients were given placebo or 80 mg simvastatin for up to 14 days. Plasma heparin-binding protein levels from patients with acute lung injury and healthy volunteers were measured by ELISA.ResultsLevels of plasma heparin-binding protein were significantly higher in patients with acute lung injury than healthy volunteers on day 0 (p = 0.011). Simvastatin 80 mg administered enterally for 14 days reduced plasma level of heparin-binding protein in patients. Reduced heparin-binding protein was associated with improved intensive care unit survival.ConclusionsA reduction in heparin-binding protein with simvastatin is a potential mechanism by which the statin may modify outcome from acute lung injury.Trial registrationCurrent controlled trials: ISRCTN70127774

Aspirin reduces lipopolysaccharide-induced pulmonary inflammation in human models of ARDS

Rationale Platelets play an active role in the pathogenesis of acute respiratory distress syndrome (ARDS). Animal and observational studies have shown aspirins antiplatelet and immunomodulatory effects may be beneficial in ARDS. Objective To test the hypothesis that aspirin reduces inflammation in clinically relevant human models that recapitulate pathophysiological mechanisms implicated in the development of ARDS. Methods Healthy volunteers were randomised to receive placebo or aspirin 75  or 1200 mg (1:1:1) for seven days prior to lipopolysaccharide (LPS) inhalation, in a double-blind, placebo-controlled, allocation-concealed study. Bronchoalveolar lavage (BAL) was performed 6 hours after inhaling 50 µg of LPS. The primary outcome measure was BAL IL-8. Secondary outcome measures included markers of alveolar inflammation (BAL neutrophils, cytokines, neutrophil proteases), alveolar epithelial cell injury, systemic inflammation (neutrophils and plasma C-reactive protein (CRP)) and platelet activation (thromboxane B2, TXB2). Human lungs, perfused and ventilated ex vivo (EVLP) were randomised to placebo or 24 mg aspirin and injured with LPS. BAL was carried out 4 hours later. Inflammation was assessed by BAL differential cell counts and histological changes. Results In the healthy volunteer (n=33) model, data for the aspirin groups were combined. Aspirin did not reduce BAL IL-8. However, aspirin reduced pulmonary neutrophilia and tissue damaging neutrophil proteases (Matrix Metalloproteinase (MMP)-8/-9), reduced BAL concentrations of tumour necrosis factor α and reduced systemic and pulmonary TXB2. There was no difference between high-dose and low-dose aspirin. In the EVLP model, aspirin reduced BAL neutrophilia and alveolar injury as measured by histological damage. Conclusions These are the first prospective human data indicating that aspirin inhibits pulmonary neutrophilic inflammation, at both low and high doses. Further clinical studies are indicated to assess the role of aspirin in the prevention and treatment of ARDS. Trial registration number NCT01659307 Results.