GAT107-mediated α7 nicotinic acetylcholine receptor signaling attenuates inflammatory lung injury and mortality in a mouse model of ventilator-associated pneumonia by alleviating macrophage mitochondrial oxidative stress via reducing MnSOD-S-glutathionylation.

Supraphysiological concentrations of oxygen (hyperoxia) can compromise host defense and increase susceptibility to bacterial and viral infections, causing ventilator-associated pneumonia (VAP). Compromised host defense and inflammatory lung injury are mediated, in part, by high extracellular concentrations of HMGB1, which can be decreased by GTS-21, a partial agonist of α7 nicotinic acetylcholine receptor (α7nAChR). Here, we report that a novel α7nAChR agonistic positive allosteric modulator (ago-PAM), GAT107, at 3.3 mg/kg, i.p., significantly decreased animal mortality and markers of inflammatory injury in mice exposed to hyperoxia and subsequently infected with Pseudomonas aeruginosa. The incubation of macrophages with 3.3 µM of GAT107 significantly decreased hyperoxia-induced extracellular HMGB1 accumulation and HMGB1-induced macrophage phagocytic dysfunction. Hyperoxia-compromised macrophage function was correlated with impaired mitochondrial membrane integrity, increased superoxide levels, and decreased manganese superoxide dismutase (MnSOD) activity. This compromised MnSOD activity is due to a significant increase in its level of glutathionylation. The incubation of hyperoxic macrophages with 3.3 µM of GAT107 significantly decreases the levels of glutathionylated MnSOD, and restores MnSOD activity and mitochondrial membrane integrity. Thus, GAT107 restored hyperoxia-compromised phagocytic functions by decreasing HMGB1 release, most likely via a mitochondrial-directed pathway. Overall, our results suggest that GAT107 may be a potential treatment to decrease acute inflammatory lung injury by increasing host defense in patients with VAP.

MUC1 ectodomain is a flagellin-targeting decoy receptor and biomarker operative during Pseudomonas aeruginosa lung infection.

We previously reported that flagellin-expressing Pseudomonas aeruginosa (Pa) provokes NEU1 sialidase-mediated MUC1 ectodomain (MUC1-ED) desialylation and MUC1-ED shedding from murine lungs in vivo. Here, we asked whether Pa in the lungs of patients with ventilator-associated pneumonia might also increase MUC1-ED shedding. The levels of MUC1-ED and Pa-expressed flagellin were dramatically elevated in bronchoalveolar lavage fluid (BALF) harvested from Pa-infected patients, and each flagellin level, in turn, predicted MUC1-ED shedding in the same patient. Desialylated MUC1-ED was only detected in BALF of Pa-infected patients. Clinical Pa strains increased MUC1-ED shedding from cultured human alveolar epithelia, and FlaA and FlaB flagellin-expressing strains provoked comparable levels of MUC1-ED shedding. A flagellin-deficient isogenic mutant generated dramatically reduced MUC1-ED shedding compared with the flagellin-expressing wild-type strain, and purified FlaA and FlaB recapitulated the effect of intact bacteria. Pa:MUC1-ED complexes were detected in the supernatants of alveolar epithelia exposed to wild-type Pa, but not to the flagellin-deficient Pa strain. Finally, human recombinant MUC1-ED dose-dependently disrupted multiple flagellin-driven processes, including Pa motility, Pa biofilm formation, and Pa adhesion to human alveolar epithelia, while enhancing human neutrophil-mediated Pa phagocytosis. Therefore, shed desialylated MUC1-ED functions as a novel flagellin-targeting, Pa-responsive decoy receptor that participates in the host response to Pa at the airway epithelial surface.

Heparin-binding protein in lower airway samples as a biomarker for pneumonia.

OBJECTIVES: Ventilator-associated pneumonia (VAP) is difficult to diagnose using clinical criteria and no biomarkers have yet been proved to be sufficiently accurate. The use of the neutrophil-derived Heparin-binding protein (HBP) as a biomarker for pneumonia was investigated in this exploratory case-control study in two intensive care units at a tertiary referral hospital. METHODS: Patients with clinical signs of pneumonia were recruited and bronchoalveolar lavage fluid (BALF) or bronchial wash (BW) samples were collected. Mechanically ventilated and lung healthy subjects were recruited as controls. HBP was measured with enzyme-linked immunosorbent assay. RESULTS: BALF was collected from 14 patients with pneumonia and 14 healthy controls. Median HBP in BALF pneumonia samples was 14,690 ng/ml and controls 16.2 ng/ml (p < 0.0001). BW was collected from 10 pneumonia patients and 10 mechanically ventilated controls. Median HBP in BW pneumonia was 9002 ng/ml and controls 7.6 ng/ml (p < 0.0001). CONCLUSIONS: These data indicate that HBP concentrations is significantly higher in lower airway samples from patients with pneumonia than control subjects and is a potentially useful biomarker for diagnosis of VAP.

Contrasting effects of linezolid on healthy and dysfunctional human neutrophils: reducing C5a-induced injury.

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of ventilator-associated pneumonia (VAP). Patients with VAP have poorly functioning neutrophils, related to increased levels of the complement fragment C5a. The antibiotic linezolid has been useful in controlling MRSA-related VAP infections; however clinical benefit does not always correlate with antimicrobial effect, suggesting the possibility of immunomodulatory properties. Here the effects of linezolid on healthy and dysfunctional neutrophils (modelled by C5a-induced injury) was investigated. Functional assays (killing, phagocytosis, transmigration, and respiratory burst) were used to assess the effects of pre-, co- and post-incubating linezolid (0.4-40 mg/L) with healthy neutrophils relative to those with C5a-induced injury. C5a decreased neutrophil killing, and phagocytosis of MRSA. Furthermore, C5a significantly decreased neutrophil transmigration to IL-8, but did not affect respiratory burst. Co-incubation of linezolid significantly improved killing of MRSA by dysfunctional neutrophils, which was supported by concomitant increases in phagocytosis. Conversely linezolid impaired killing responses in healthy neutrophils. Pre- or post-incubation of linezolid prior or following C5a induced injury had no effect on neutrophil function. This study suggests that linezolid has immunomodulatory properties that protect human neutrophils from injury and provides insight into its mode of action beyond a basic antibiotic.

Evaluation of Epithelial Lining Fluid Concentration of Amikacin in Critically Ill Patients With Ventilator-Associated Pneumonia.

INTRODUCTION: Classically, aminoglycosides are known to have low penetration into the lung tissue. So far, no study has been conducted on human adult patients to evaluate amikacin concentration in epithelial lining fluid (ELF) of the alveoli. Therefore, convincing data are not available from the perspective of pharmacokinetics to support the fact that a dosage of 20 mg/kg of amikacin is sufficient to treat patients with ventilator-associated pneumonia (VAP). METHOD: This was a pilot study of amikacin concentration measurement in the alveolar site of action in critically ill adult patients with VAP who required aminoglycoside therapy. A dose of 20 mg/kg of amikacin was administered over a 30-minute infusion. The serum concentrations of amikacin were evaluated in the first, second, fourth, and sixth hours. However, the ELF concentration of amikacin was evaluated in the second hour with the help of bronchoalveolar lavage sampling technique. RESULTS: A total number of 8 patients was included in the study. The mean (SD) administered dose was 20 (0.9) mg/kg. The mean (SD) peak plasma concentration of amikacin was 59.6 (23) mg/L, with the volume of distribution of 0.36 (0.13)L/kg. The amikacin concentration in ELF was successfully measured in 7 patients (6.3) mg/L. The lung tissue penetration of the drug was described as alveolar percentage, proportional to both the first- and second-hour plasma concentrations, with a mean (SD) of 10.1% (8.4%) and 18% (16.7%), respectively. CONCLUSION: To our knowledge, the current study is the first that investigates whether standard doses of amikacin may lead to sufficient alveolar concentration of the drug. The results show that administration of amikacin in doses of 20 mg/kg in critically ill patients with VAP may not provide sufficient concentrations in ELF.

Mechanical Ventilation Impairs IL-17 Cytokine Family Expression in Ventilator-Associated Pneumonia.

Mechanical ventilation (MV) is the primary risk factor for the development of ventilator-associated pneumonia (VAP). Besides inducing a pro-inflammatory T-helper (Th)-1 cytokine response, MV also induces an anti-inflammatory Th2 cytokine response, marked by increased IL-4 secretion and reduced bacterial phagocytic capacity of rodent lung macrophages. Since IL-4 is known to downregulate both Th1 and Th17 cytokines, the latter is important in mediating mucosal immunity and combating bacterial and fungal growth, we studied and showed here in a rat model of MV that Th17 cytokines (IL-17A, IL-17F, and IL-22) were significantly upregulated in the lung as a response to different MV strategies currently utilized in clinic. To study whether the increased IL-4 levels are associated with downregulation of the anti-bacterial Th17 cytokines, we subsequently challenged mechanically ventilated rats with an intratracheal inoculation of Pseudomonas aeruginosa (VAP model) and showed a dramatic downregulation of IL-17A, IL-17F, and IL-22, compared to animals receiving the same bacterial burden without MV. For the studied Th1 cytokines (IFN, TNF, IL-6, and IL-1), only IFN showed a significant decrease as a consequence of bacterial infection in mechanically ventilated rats. We further studied IL-17A, the most studied IL-17 family member, in intensive care unit (ICU) pneumonia patients and showed that VAP patients had significantly lower levels of IL-17A in the endotracheal aspirate compared to patients entering ICU with pre-existing pneumonia. These translational data, obtained both in animal models and in humans, suggest that a deficient anti-bacterial Th17 response in the lung during MV is associated with VAP development.

Dual effects of human neutrophil peptides in a mouse model of pneumonia and ventilator-induced lung injury.

BACKGROUND: Pneumonia is a major cause of high morbidity and mortality in critically illness, and frequently requires support with mechanical ventilation. The latter can lead to ventilator-induced lung injury characterized by neutrophil infiltration. The cationic human neutrophil peptides (HNP) stored in neutrophils can kill microorganisms, but excessive amount of HNP released during phagocytosis may contribute to inflammatory responses and worsen lung injury. Based on our previous work, we hypothesized that blocking the cell surface purinergic receptor P2Y6 will attenuate the HNP-induced inflammatory responses while maintaining their antimicrobial activity in pneumonia followed by mechanical ventilation. METHODS: Plasma HNP levels were measured in patients with pneumonia who received mechanical ventilation and in healthy volunteers. FVB littermate control and HNP transgenic (HNP+) mice were randomized to receive P. aeruginosa intranasally. The P2Y6 antagonist (MRS2578) or vehicle control was given after P. aeruginosa instillation. Additional mice underwent mechanical ventilation at either low pressure (LP) or high pressure (HP) ventilation 48 h after pneumonia, and were observed for 24 h. RESULTS: Plasma HNP concentration increased in patients with pneumonia as compared to healthy subjects. The bacterial counts in the bronchoalveolar lavage fluid (BALF) were lower in HNP+ mice than in FVB mice 72 h after P. aeruginosa instillation. However, upon receiving HP ventilation, HNP+ mice had higher levels of cytokines and chemokines in BALF than FVB mice. These inflammatory responses were attenuated by the treatment with MRS2578 that did not affect the microbial effects of HNP. CONCLUSIONS: HNP exerted dual effects by exhibiting antimicrobial activity in pneumonia alone condition while enhancing inflammatory responses in pneumonia followed by HP mechanical ventilation. Blocking P2Y6 can attenuate the inflammation without affecting the antibacterial property of HNP. The P2Y6 receptor may be a novel therapeutic target in attenuation of the leukocyte-mediated excessive host responses in inflammatory lung diseases.

The Role of Presepsin Obtained from Tracheal Aspirates in the Diagnosis of Early Onset Pneumonia in Intubated Newborns.

OBJECTIVES: To investigate the role of presepsin obtained from tracheal aspirate of intubated newborns in the diagnosis of early neonatal pneumonia. METHODS: A cross-sectional observational study was performed on 60 intubated newborns during the two-year period. Tracheal aspirate for examination was taken in aseptic conditions in usual toilets, by lavage with 2 ml of 0.9% NaCl in Mucus suction set. On the same day, presepsin (blood) was measured. RESULTS: There were 34 newborns in the examined group (with pneumonia) and 26 in the control group. Patient groups were similar regarding demographic characteristics related to gender and Apgar score. The coefficients of simple linear correlation revealed the statistically significant connection between presepsin (from tracheal aspirate) and birth body weight, presepsin (plasma), maternal infection and pneumonia. Significant differences in the values of presepsin (from tracheal aspirate) (p < 0.001) and birth body weight (p = 0.036) were found. CONCLUSIONS: In intubated newborns, measurements of presepsin obtained from tracheal aspirate suggested that it can be used as a complementary marker in diagnosing early onset neonatal pneumonia.

A pilot randomized clinical trial assessing the effect of cricoid pressure on risk of aspiration.

INTRODUCTION: Patients at risk for microaspiration during elective intubation often receive cricoid pressure in the hopes of mitigating such risk. However, there is scarce evidence to either support or reject this practice. The objective of this investigation was to assess the effect of cricoid pressure on microaspiration and to inform the potential feasibility of conducting a larger, more definitive clinical trial. METHODS: This was a pilot randomized clinical trial set in the operating rooms of a tertiary referral hospital between August and October of 2014. Patients with risk factors for microaspiration (obesity, gastroesophageal reflux disease, or diabetes) were enrolled. The patients were randomized to either cricoid pressure or no cricoid pressure during induction of anesthesia with endotracheal intubation. Immediately after intubation, a sample of lower airway secretions was collected and analyzed for pepsin A. MAIN RESULTS: A total of 95 patients were evaluated, randomized and completed the study protocol. 46 were randomized to cricoid pressure and 49 to no cricoid pressure. Seven patients crossed-over treatment arms. A total of 18 (19.6%) patients met the pre-defined criteria for microaspiration. In both the intention-to-treat and per-protocol analyses, there were no statistically significant differences in the rate of microaspiration [OR (95% CI)] = 1.39 (0.49-3.92) and 1.30 (0.44-3.86), respectively. CONCLUSIONS: Utilizing pepsin A as a biomarker of aspiration, this pilot clinical trial did not find evidence for a reduced rate of aspiration or adverse clinical events with the administration of cricoid pressure during elective endotracheal intubation of patients with risk factors for microaspiration.

The study of vitamin D administration effect on CRP and Interleukin-6 as prognostic biomarkers of ventilator associated pneumonia.

PURPOSE: In regard with the effect of immune-stimulants in the treatment of infectious diseases, the effect of vitamin D administration on the outcome of patients with Ventilator-Associated Pneumonia (VAP) with a high rate of mortality, was studied. MATERIAL AND METHOD: In this trial, 46 adult patients suffering from VAP and vitamin D deficiency were enrolled. The first group of patients received single intramuscular injection of vitamin D (300000Unit), while the other group were given the placebo. RESULTS: Administration of vitamin D significantly enhanced its levels (P<0.0001) in the treated patients (12.28±8.26) in comparison with placebo group (1.15±1.50). Serum Interleukin-6 levels were significantly reduced in the treated group compared to placebo (P=0.01). Although C-Reactive protein (CRP) levels showed an improving trend in the vitamin D group, no significant difference between groups (P=0.12) was found. Interestingly, the mortality rate of patients that treated with vitamin D (5/24) was significantly lower (p=0.04) than that of the placebo group (11/22). CONCLUSION: Our results indicate that vitamin D administration can significantly reduce the IL-6 as prognostic marker in VAP patients, and must be considered as adjunct option in the treatment of VAP patients.

Serum and alveolar procalcitonin had a weak diagnostic value for ventilator-associated pneumonia in patients with pulmonary infection score ≥ 6.

BACKGROUND: Measuring the serum and alveolar procalcitonin level as inflammatory marker in the diagnosis of ventilator-associated pneumonia (VAP) has been taken into account. In this study, serum and alveolar procalcitonin levels in patients with suspected VAP and patients with confirmed VAP were compared. METHODS: This cross-sectional study was conducted using 50 intubated intensive care unit (ICU) patients, connected to ventilator, from October 2014 to April 2015. 50 patients with clinical pulmonary infection score ≥6 were divided into two groups. Patients whose bronchoalveolar lavage (BAL) has shown the growth of more than 104 CFU/mL were included in confirmed VAP group and other patients were included in suspected VAP group. Serum and alveolar procalcitonin levels were measured and compared between both groups. RESULTS: Mean age of patients was 69.10 ± 42.13 with a range of 16-90 years, out of which 23 patients were male (46%) and 27 patients were female (54%). Moreover, patients' mean clinical pulmonary infection score was reported to be 7.02 ± 1.07. There was a significant relationship between serum and alveolar procalcitonin in suspected patients and patients with an approved form of pneumonia (p = 0.001 and 0.027). Area under the curve for alveolar procalcitonin was 0.683 (sensitivity = 57%; specificity = 80%) and for serum procalcitonin 0.751 (sensitivity = 71%; specificity = 73%) for the diagnosis of VAP. CONCLUSION: According to the results of the present study, we can diagnose ventilator-associated pneumonia earlier and more accurately by measuring procalcitonin level (particularly alveolar type) in intensive care unit patients.

Biomarkers kinetics in the assessment of ventilator-associated pneumonia response to antibiotics - results from the BioVAP study.

PURPOSE: Our aim was to evaluate the role of biomarker kinetics in the assessment of ventilator-associated pneumonia (VAP) response to antibiotics. MATERIALS AND METHODS: We performed a prospective, multicenter, observational study to evaluate in 37 microbiologically documented VAP, the kinetics of C-reactive protein (CRP), procalcitonin (PCT), mid-region fragment of pro-adrenomedullin (MR-proADM). The kinetics of each variable, from day 1 to 6 of therapy, was assessed with a time dependent analysis comparing survivors and non-survivors. RESULTS: During the study period kinetics of CRP as well as its relative changes, CRP-ratio, was significantly different between survivors and non-survivors (p=0.026 and p=0.005, respectively). On day 4 of antibiotic therapy, CRP of survivors was 47% of the initial value while it was 96% in non-survivors. The kinetics of other studied variables did not distinguish between survivors and non-survivors. In survivors the bacterial load also decreased markedly. Adequate initial antibiotic therapy was associated with lower mortality (p=0.025) and faster CRP decrease (p=0.029). CONCLUSIONS: C-reactive protein kinetics can be used to identify VAP patients with poor outcome as soon as four days after the initiation of treatment. (Trial registration - NCT02078999; registered 3 August 2012).

Exhaled Breath Metabolomics for the Diagnosis of Pneumonia in Intubated and Mechanically-Ventilated Intensive Care Unit (ICU)-Patients.

The diagnosis of hospital-acquired pneumonia remains challenging. We hypothesized that analysis of volatile organic compounds (VOCs) in exhaled breath could be used to diagnose pneumonia or the presence of pathogens in the respiratory tract in intubated and mechanically-ventilated intensive care unit patients. In this prospective, single-centre, cross-sectional cohort study breath from mechanically ventilated patients was analysed using gas chromatography-mass spectrometry. Potentially relevant VOCs were selected with a p-value < 0.05 and an area under the receiver operating characteristics curve (AUROC) above 0.7. These VOCs were used for principal component analysis and partial least square discriminant analysis (PLS-DA). AUROC was used as a measure of accuracy. Ninety-three patients were included in the study. Twelve of 145 identified VOCs were significantly altered in patients with pneumonia compared to controls. In colonized patients, 52 VOCs were significantly different. Partial least square discriminant analysis classified patients with modest accuracy (AUROC: 0.73 (95% confidence interval (CI): 0.57-0.88) after leave-one-out cross-validation). For determining the colonization status of patients, the model had an AUROC of 0.69 (95% CI: 0.57-0.82) after leave-one-out cross-validation. To conclude, exhaled breath analysis can be used to discriminate pneumonia from controls with a modest to good accuracy. Furthermore breath profiling could be used to predict the presence and absence of pathogens in the respiratory tract. These findings need to be validated externally.

Add-on effect of Qinbei Qingfei Yiqi granules for ventilator-associated pneumonia in intensive care units: a randomized controlled trial.

OBJECTIVE: To evaluate the add-on effect of Qinbei Qingfei Yiqi (QBQFYQ) granules for ventilator-associated pneumonia (VAP) in non-infectious critically ill patients. METHODS: In this randomized controlled trial, 80 non-infectious critically ill patients undergoing mechanical ventilation in the intensive care unit (ICU) were randomly divided into two groups: those receiving QBQFYQ granules plus usual treatment (experimental group, n = 50) and those receiving only the usual treatment (control group, n = 30). The main outcome measures were VAP rate, time of VAP occurrence, duration of mechanical ventilation, and length of ICU stay. Interleukin-6 (IL-6), C-reactive protein (CRP), and T-lymphocyte (CD4+, CD8+, and CD4+/CD8+ ratio) serum levels were also evaluated before and after treatment. RESULTS: Compared with the control group treatment QBQFYQ administration significantly reduced the duration of mechanical ventilation [(9.58 ± 3.14) vs (12.52 ± 4.33) days] and length of ICU stay [(14.57 ± 3.72) vs (17.82 ± 5.24) days] and delayed VAP occurrence [(4.31 ± 0.86) vs (2.43 ± 0.27) days]. Additionally, CRP and IL-6 serum levels and CD4+/CD8+ ratio were significantly lower in the experimental group (P < 0.05) than in the control group. However, there were no significant differences in hospital mortality rate (30.0% vs 33.3% ) and adverse events (4.0% vs 6.7%). adverse events (4.0% vs 6.7%). CONCLUSION: QBQFYQ delays the time of VAP occurrence and shortens the duration of mechanical ventilation in non-infectious critically ill patients, possibly through anti-inflammatory and immunomodulatory mechanisms.

Could soluble urokinase plasminogen receptor (suPAR) be used as a diagnostic biomarker for ventilator-associated pneumonia?

BACKGROUND: Soluble urokinase plasminogen activator receptor (suPAR) is a biomarker that is increasingly used for evaluation of systemic inflammation. This study was performed to investigate whether suPAR may possess a diagnostic value in patients with ventilator-associated pneumonia (VAP). METHODS: This clinical study was performed in the anesthesia intensive care units (ICUs) of our university. In addition to descriptive data, WBC, serum levels of C-reactive protein (CRP) and suPAR prior to and after development of VAP were noted and compared in 31 patients (22 men, 9 women) diagnosed with VAP (Study Group) and 19 patients without VAP (Control Group) in ICU (14 men, 5 women). RESULTS: The suPAR (P = 0.023), CRP (P = 0.037), WBCs (P = 0.024) in patients with VAP were significantly higher than patients without VAP. There was no remarkable difference in terms of WBCs (P = 0.052) and suPAR levels (P = 0.616) between groups on the first day of connection to mechanical ventilator. The suPAR and CRP levels in patients with VAP were significantly higher than prior to development of VAP (P = 0.001 for both). Area under curve value after diagnosis of pneumonia was found 0.248 (P = 0.002). CONCLUSION: To conclude, our results suggest that suPAR can be a useful diagnostic biomarker in patients with VAP. However, clinical trials on larger series are warranted to explore the clinical significance more accurately.

Pseudomonas aeruginosa colonization enhances ventilator-associated pneumonia-induced lung injury.

BACKGROUND: Pseudomonas aeruginosa (PA) is the single-most common pathogen of ventilator-associated pneumonia (VAP). Large quantities of PA in the trachea of ventilated patients are associated with an increased risk of death. However, the role of PA colonization in PA VAP-induced lung injury remains elusive. This study examined the effect and mechanism of PA colonization in VAP-induced lung injury. METHODS: C57BL/6 wild-type (WT) and c-Jun N-terminal kinase knockout (JNK1(-/-)) mice received mechanical ventilation for 3 h at 2 days after receiving nasal instillation of PA (1 × 10(6) colony forming unit) or normal saline. RESULTS: Intranasal instillation of PA or mechanical ventilation induced the expression of interleukin-6 (IL-6) in the lungs. Phospho-JNK protein expression in the lungs was significantly increased in mice receiving mechanical ventilation after PA instillation as compared with those receiving ventilation alone. Mechanical ventilation after PA instillation significantly increased the expression of tumor necrosis factor-α (TNF-α), IL-1ß, and macrophage inflammatory protein-2 (MIP-2) proteins; neutrophil sequestration; and TNF-α, IL-1ß, and IL-6 levels in the lungs of WT mice, but not in JNK1(-/-) mice. CONCLUSION: PA colonization plays an important role in PA VAP-induced lung injury through the induction of JNK1-mediated inflammation. PA-induced VAP causes lung injury through JNK signaling pathway in the lungs. JNK inhibition in ICU patients with higher percentages of PA colonization may reduce VAP-induced lung injury and mortality.

Spinal cord injury modulates the lung inflammatory response in mechanically ventilated rats: a comparative animal study.

Mechanical ventilation (MV) is widely used in spinal injury patients to compensate for respiratory muscle failure. MV is known to induce lung inflammation, while spinal cord injury (SCI) is known to contribute to local inflammatory response. Interaction between MV and SCI was evaluated in order to assess the impact it may have on the pulmonary inflammatory profile. Sprague Dawley rats were anesthetized for 24 h and randomized to receive either MV or not. The MV group included C4-C5 SCI, T10 SCI and uninjured animals. The nonventilated (NV) group included T10 SCI and uninjured animals. Inflammatory cytokine profile, inflammation related to the SCI level, and oxidative stress mediators were measured in the bronchoalveolar lavage (BAL). The cytokine profile in BAL of MV animals showed increased levels of TNF-α, IL-1ß, IL-6 and a decrease in IL-10 (P = 0.007) compared to the NV group. SCI did not modify IL-6 and IL-10 levels either in the MV or the NV groups, but cervical injury induced a decrease in IL-1ß levels in MV animals. Cervical injury also reduced MV-induced pulmonary oxidative stress responses by decreasing isoprostane levels while increasing heme oxygenase-1 level. The thoracic SCI in NV animals increased M-CSF expression and promoted antioxidant pulmonary responses with low isoprostane and high heme oxygenase-1 levels. SCI shows a positive impact on MV-induced pulmonary inflammation, modulating specific lung immune and oxidative stress responses. Inflammation induced by MV and SCI interact closely and may have strong clinical implications since effective treatment of ventilated SCI patients may amplify pulmonary biotrauma.

Gene expression profile analysis of ventilator-associated pneumonia.

Based on the gene expression profile of patients with ventilator-associated pneumonia (VAP) and patients not affected by the disease, the present study aimed to enhance the current understanding of VAP development using bioinformatics methods. The expression profile GSE30385 was downloaded from the Gene Expression Omnibus database. The Linear Models for Microarray Data package in R language was used to screen and identify differentially expressed genes (DEGs), which were grouped as up­ and down­regulated genes. The up­ and downregulated genes were functionally enriched using the Database for Annotation, Visualization and Integrated Discovery system and then annotated according to TRANSFAC, Tumor Suppressor Gene and Tumor Associated Gene databases. Subsequently, the protein­protein interaction (PPI) network was constructed, followed by module analysis using CFinder software. A total of 69 DEGs, including 33 up­ and 36 downregulated genes were screened out in patients with VAP. Upregulated genes were mainly enriched in functions and pathways associated with the immune response (including the genes ELANE and LTF) and the mitogen-activated protein kinase (MAPK) signaling pathway (including MAPK14). The PPI network comprised 64 PPI pairs and 44 nodes. The top two modules were enriched in different pathways, including the MAPK signaling pathway. Genes including ELANE, LTF and MAPK14 may have important roles in the development of VAP via altering the immune response and the MAPK signaling pathway.

Lung concentrations of ceftazidime administered by continuous versus intermittent infusion in patients with ventilator-associated pneumonia.

Ceftazidime is a beta-lactam compound that exerts a time-dependent bactericidal effect. Numerous arguments are in favor of continuous administration of ceftazidime, both for reasons of clinical efficacy and to preserve bacteriological mutation. We report a prospective, single-center, parallel-group, randomized, controlled trial comparing two modes of administration of ceftazidime, namely, continuous administration (loading dose of 20 mg/kg of body weight followed by 60 mg/kg/day) versus intermittent administration (20 mg/kg over 30 min every 8 h) in 34 patients with ventilator-associated pneumonia due to Gram-negative bacilli. The study was performed over 48 h with 13 and 18 assessments of serum ceftazidime in the continuous-infusion group (group A) and the intermittent-fusion group (group B), respectively. Bronchoalveolar lavage (BAL) was performed at steady state in both groups at 44 h to determine ceftazidime levels in the epithelial lining fluid. We chose a predefined threshold of 20 mg/liter for serum concentrations of ceftazidime because of ecological conditions in our center. The median time above 20 mg/liter (T>20 mg) was 100% in group A versus 46% in group B. In group A, 14/17 patients had 100% T>20 mg, versus only 1/17 patients in group B. In the epithelial lining fluid, the median concentration of ceftazidime was 12 mg/liter in group A versus 6 mg/liter in group B. A threshold of 8 mg/liter in the epithelial lining fluid was achieved twice as often in group A as in group B. This study of ceftazidime concentrations in the epithelial lining fluid indicates that continuous infusion presents advantages in terms of pharmacodynamics and predictable efficacy in patients presenting ventilator-associated pneumonia.

Population pharmacokinetics of single-dose amikacin in critically ill patients with suspected ventilator-associated pneumonia.

AIMS: Modifications of antimicrobials' pharmacokinetic parameters have been reported in critically ill patients, resulting in a risk of treatment failure. We characterized amikacin pharmacokinetic variability in critically ill patients with ventilator-associated pneumonia (VAP) and evaluated several dosing regimens. METHODS: We conducted a prospective multicenter study in critically ill patients with presumptive diagnosis of Gram-negative bacilli (GNB) VAP. Patients empirically received imipenem and a single-dose of amikacin, which was administered as a 30-min infusion (20 mg/kg). Concentrations were measured 0.5, 1, 8, 16, and 24 h after beginning of infusion. Pharmacokinetic parameters were estimated using a population approach. Main pharmacodynamic target was a ratio ≥ 10 between the concentration achieved 1 h after beginning of infusion (C 1h) and the minimal inhibitory concentration of the liable bacteria (MIC). We simulated individual C 1h for several dosing regimens by Monte Carlo method and computed C 1h/MIC ratios for MICs from 0.5 to 64 mg/L. RESULTS: Sixty patients (47 males), median (range) age, and body weight, 61.5 years (28-84) and 78 kg (45-126), respectively, were included. Amikacin median C 1h was 45 mg/L (22-87). Mean value (between-patients variability) for CL, V1, Q, and V2 were 4.3 L/h (31 %), 15.9 L (22 %), 12.1 L/h (27 %), and 21.4 L (47 %), respectively. CL increased with CrCL (p<0.001) and V1 with body weight (p<0.001) and PaO2/FIO2 ratio (p<0.001). With a 25 mg/kg regimen, the pharmacodynamic target was achieved in 20 and 96 % for a MICs of 8 and 4 mg/L, respectively. CONCLUSION: Amikacin clearance was decreased and its volume of distribution was increased as previously reported. A ≥ 25 mg/kg single-dose is needed for empirical treatment of GNB-VAP.