Adverse Mechanical Ventilation and Pneumococcal Pneumonia Induce Immune and Mitochondrial Dysfunctions Mitigated by Mesenchymal Stem Cells in Rabbits.

BACKGROUND: Mechanical ventilation for pneumonia may contribute to lung injury due to factors that include mitochondrial dysfunction, and mesenchymal stem cells may attenuate injury. This study hypothesized that mechanical ventilation induces immune and mitochondrial dysfunction, with or without pneumococcal pneumonia, that could be mitigated by mesenchymal stem cells alone or combined with antibiotics. METHODS: Male rabbits underwent protective mechanical ventilation (8 ml/kg tidal volume, 5 cm H2O end-expiratory pressure) or adverse mechanical ventilation (20 ml/kg tidal-volume, zero end-expiratory pressure) or were allowed to breathe spontaneously. The same settings were then repeated during pneumococcal pneumonia. Finally, infected animals during adverse mechanical ventilation received human umbilical cord-derived mesenchymal stem cells (3 × 106/kg, intravenous) and/or ceftaroline (20 mg/kg, intramuscular) or sodium chloride, 4 h after pneumococcal challenge. Twenty-four-hour survival (primary outcome), lung injury, bacterial burden, immune and mitochondrial dysfunction, and lung transcriptomes (secondary outcomes) were assessed. RESULTS: High-pressure adverse mechanical ventilation reduced the survival of infected animals (0%; 0 of 7) compared with spontaneous breathing (100%; 7 of 7) and protective mechanical ventilation (86%; 6 of 7; both P < 0.001), with higher lung pathology scores (median [interquartile ranges], 5.5 [4.5 to 7.0] vs. 12.6 [12.0 to 14.0]; P = 0.046), interleukin-8 lung concentrations (106 [54 to 316] vs. 804 [753 to 868] pg/g of lung; P = 0.012), and alveolar mitochondrial DNA release (0.33 [0.28 to 0.36] vs. 0.98 [0.76 to 1.21] ng/µl; P < 0.001) compared with infected spontaneously breathing animals. Survival (0%; 0 of 7; control group) was improved by mesenchymal stem cells (57%; 4 of 7; P = 0.001) or ceftaroline alone (57%; 4 of 7; P < 0.001) and improved even more with a combination treatment (86%; 6 of 7; P < 0.001). Mesenchymal stem cells reduced lung pathology score (8.5 [7.0 to 10.5] vs. 12.6 [12.0 to 14.0]; P = 0.043) and alveolar mitochondrial DNA release (0.39 (0.34 to 0.65) vs. 0.98 (0.76 to 1.21) ng/µl; P = 0.025). Mesenchymal stem cells combined with ceftaroline reduced interleukin-8 lung concentrations (665 [595 to 795] vs. 804 [753 to 868] pg/g of lung; P = 0.007) compared to ceftaroline alone. CONCLUSIONS: In this preclinical study, mesenchymal stem cells improved the outcome of rabbits with pneumonia and high-pressure mechanical ventilation by correcting immune and mitochondrial dysfunction and when combined with the antibiotic ceftaroline was synergistic in mitigating lung inflammation.

Mucormycosis in intensive care unit: surgery is a major prognostic factor in patients with hematological malignancy.

BACKGROUND: Mucormycosis is an invasive fungal infection, with an increasing incidence especially in patients with hematological malignancies. Its prognosis is poor because of its high invasive power and its intrinsic low susceptibility to antifungal agents. We aimed to describe the epidemiology of mucormycosis in intensive care units (ICU) and evaluate the outcomes. We performed a retrospective multi-center study in 16 French ICUs between 2008 and 2017. We compared the patients who survived in ICU and the patients who did not to identify factors associated with ICU survival. Then, we focused on the subgroup of patients with hematological malignancies. RESULTS: Mucormycosis was diagnosed in 74 patients during the study period. Among them, 60 patients (81%) were immunocompromised: 41 had hematological malignancies, 9 were solid organ transplant recipients, 31 received long-term steroids, 11 had diabetes, 24 had malnutrition. Only 21 patients survived to ICU stay (28.4%) with a median survival of 22 days (Q1-Q3 = 9-106) and a survival rate at day 28 and day 90, respectively, of 35.1% and 26.4%. Survivors were significantly younger (p = 0.001), with less frequently hematological malignancies (p = 0.02), and less malnutrition (p = 0.05). Median survival in patients with hematological malignancies (n = 41) was 15 days (Q1-Q3 = 5-23.5 days). In this subgroup, curative surgery was a major factor associated with survival in multivariate analysis (odds ratio = 0.71, [0.45-0.97], p < 0.001). CONCLUSION: Overall prognosis of mucormycosis in ICU remains poor, especially in patients with hematological malignancies. In this subgroup of patients, a therapeutic strategy including curative surgery was the main factor associated with survival.

Mitochondrial alarmins are tissue mediators of ventilator-induced lung injury and ARDS.

RATIONALE: Endogenous tissue mediators inducing lung inflammation in the context of ventilator-induced lung injury (VILI) and acute respiratory distress syndrome (ARDS) are ill-defined. OBJECTIVES: To test whether mitochondrial alarmins are released during VILI, and are associated with lung inflammation. METHODS: Release of mitochondrial DNA, adenosine triphosphate (ATP), and formyl-Met-Leu-Phe (fMLP) peptide-dependent neutrophil chemotaxis were measured in conditioned supernatants from human alveolar type II-like (A549) epithelial cells submitted to cyclic stretch in vitro. Similar measurements were performed in bronchoalveolar lavage fluids from rabbits submitted to an injurious ventilatory regimen, and from patients with ARDS. MEASUREMENTS AND MAIN RESULTS: Mitochondrial DNA was released by A549 cells during cell stretching, and was found elevated in BAL fluids from rabbits during VILI, and from ARDS patients. Cyclic stretch-induced interleukin-8 (IL-8) of A549 cells could be inhibited by Toll-like receptor 9 (TLR9) blockade. ATP concentrations were increased in conditioned supernatants from A549 cells, and in rabbit BAL fluids during VILI. Neutrophil chemotaxis induced by A549 cells conditioned supernatants was essentially dependent on fMLP rather than IL-8. A synergy between cyclic stretch-induced alarmins and lipopolysaccharide (LPS) was found in monocyte-derived macrophages in the production of IL-1ß. CONCLUSIONS: Mitochondrial alarmins are released during cyclic stretch of human epithelial cells, as well as in BAL fluids from rabbits ventilated with an injurious ventilatory regimen, and found in BAL fluids from ARDS patients, particularly in those with high alveolar inflammation. These alarmins are likely to represent the proximal endogenous mediators of VILI and ARDS, released by injured pulmonary cells.

Adhering to the procalcitonin algorithm allows antibiotic therapy to be shortened in patients with ventilator-associated pneumonia.

PURPOSE: Ventilator-associated pneumonia (VAP) increases exposure to antibiotics. Physicians are however reluctant to shorten treatment, arguing this could lead to failures and worse outcome. Monitoring procalcitonin (PCT) has proven effective for decreasing exposure to antibiotics in randomized controlled trials, but additional "real-life" studies are needed. MATERIALS AND METHODS: All patients with VAP in whom ABT was stopped before death or discharge were included in this 5-year prospective cohort study. Patients in whom ABT was stopped in accordance with the algorithm ("PCT-guided" group: ABT withdrawal strongly encouraged if PCT < 0.5 ng/mL or < 80% peak value) were compared to those with ABT continuation despite PCT decrease ("not PCT-guided" group). The primary endpoint was ABT duration. The secondary endpoint was unfavorable VAP outcome (i.e. death or relapse). RESULTS: We included 157 of the 316 patients with microbiologically-proven VAP. The algorithm was overruled in 81 patients (51.6%). ABT duration was significantly longer in these patients than in the PCT-guided group (9.5 vs. 8.0 days; p = .02), although baseline and VAP characteristics did not differ. The rate of unfavorable outcomes was comparable (46.9% vs. 51.3%; p = .69). CONCLUSIONS: PCT-guided ABT adherence appears safe for patients with VAP and is likely to reduce exposure to antibiotics.

Mechanical ventilation and Streptococcus pneumoniae pneumonia alter mitochondrial homeostasis.

Required mechanical ventilation (MV) may contribute to bacterial dissemination in patients with Streptococcus pneumoniae pneumonia. Significant variations in plasma mitochondrial DNA (mtDNA) have been reported in sepsis according to the outcome. The impact of lung stretch during MV was addressed in a model of pneumonia. Healthy or S. pneumoniae infected rabbits were submitted to MV or kept spontaneously breathing (SB). Bacterial burden, cytokines release, mitochondrial DNA levels, integrity and transcription were assessed along with 48-hour mortality. Compared with infected SB rabbits, MV rabbits developed more severe pneumonia with greater concentrations of bacteria in the lungs, higher rates of systemic dissemination, higher levels of circulating inflammatory mediators and decreased survival. Pulmonary mtDNA levels were significantly lower in infected animals as compared to non-infected ones, whenever they were SB or MV. After a significant early drop, circulating mtDNA levels returned to baseline values in the infected SB rabbits, but remained low until death in the MV ones. Whole blood ex-vivo stimulation with Streptococcus pneumoniae resulted in a reduction of polymorphonuclear leukocytes mitochondrial density and plasma mtDNA concentrations. Thus, persistent mitochondrial depletion and dysfunction in the infected animals submitted to MV could account for their less efficient immune response against S. pneumoniae.

Safety and efficacy of transcatheter embolization with Glubran®2 cyanoacrylate glue for acute arterial bleeding: a single-center experience with 104 patients.

PURPOSE: To assess the efficacy and the safety of Glubran®2 n-butyl cyanoacrylate metacryloxysulfolane (NBCA-MS) transcatheter arterial embolization (TAE) for acute arterial bleeding from varied anatomic sites and to evaluate the predictive factors associated with clinical success and 30-day mortality. METHODS: A retrospective review of consecutive patients who underwent emergent NBCA-MS Glubran®2 TAE between July 2014 and August 2016 was conducted. Variables including age, sex, underlying malignancy, cardiovascular comorbidities, coagulation data, systolic blood pressure, and number of red blood cells units (RBC) transfused before TAE were collected. Clinical success, 30-day mortality, and complication rates were evaluated. Prognostic factors were evaluated by uni- and multivariate logistic regression analyses for clinical success, and by uni- and bivariate analyses after adjustment by bleeding sites for 30-day mortality. RESULTS: 104 patients underwent technically successful embolization with bleeding located in muscles (n = 34, 32.7%), digestive tract (n = 28, 26.9%), and viscera (n = 42, 40.4%). Clinical success rate was 76% (n = 79) and 30-day mortality rate was 21.2% (n = 22). Clinical failure was significantly associated with mortality (p < 0.0001). A number of RBC units transfused greater than or equal to 3 were associated with poorer clinical success (p = 0.025) and higher mortality (p = 0.03). Complications (n = 4, 3.8%) requiring surgery occurred only at puncture site. No ischemic complications requiring further invasive treatment occurred. Mean TAE treatment time was 4.55 min. CONCLUSIONS: NBCA-MS Glubran®2 TAE is a fast, effective, and safe treatment for acute arterial bleeding whatever the bleeding site.

Mechanical Ventilation Alters the Development of Staphylococcus aureus Pneumonia in Rabbit.

Ventilator-associated pneumonia (VAP) is common during mechanical ventilation (MV). Beside obvious deleterious effects on muco-ciliary clearance, MV could adversely shift the host immune response towards a pro-inflammatory pattern through toll-like receptor (TLRs) up-regulation. We tested this hypothesis in a rabbit model of Staphylococcus aureus VAP. Pneumonia was caused by airway challenge with S. aureus, in either spontaneously breathing (SB) or MV rabbits (n = 13 and 17, respectively). Pneumonia assessment regarding pulmonary and systemic bacterial burden, as well as inflammatory response was done 8 and 24 hours after S. aureus challenge. In addition, ex vivo stimulations of whole blood taken from SB or MV rabbits (n = 7 and 5, respectively) with TLR2 agonist or heat-killed S. aureus were performed. Data were expressed as mean±standard deviation. After 8 hours of infection, lung injury was more severe in MV animals (1.40±0.33 versus [vs] 2.40±0.55, p = 0.007), along with greater bacterial concentrations (6.13±0.63 vs. 4.96±1.31 colony forming units/gram, p = 0.002). Interleukin (IL)-8 and tumor necrosis factor (TNF)-αserum concentrations reached higher levels in MV animals (p = 0.010). Whole blood obtained from MV animals released larger amounts of cytokines if stimulated with TLR2 agonist or heat-killed S. aureus (e.g., TNF-α: 1656±166 vs. 1005±89; p = 0.014). Moreover, MV induced TLR2 overexpression in both lung and spleen tissue. MV hastened tissue injury, impaired lung bacterial clearance, and promoted a systemic inflammatory response, maybe through TLR2 overexpression.

Cerebral aspergillosis in adult critically ill patients: a descriptive report of 10 patients from the AspICU cohort.

An unexpectedly high incidence of invasive pulmonary aspergillosis (IPA) has been reported in non-neutropenic intensive care unit (ICU) patients. After the respiratory tract, the brain is most often affected by invasive aspergillosis. However, little is known about brain involvement by Aspergillus in critically ill patients. In this study, demographics, risk profile, diagnosis, treatment and outcome of proven cases of invasive cerebral aspergillosis (ICA) taken from a cohort of 563 adult patients with evidenced Aspergillus involvement during their ICU stay were reviewed. Ten patients with central nervous system aspergillosis were identified. All had one or more host factors predisposing for invasive aspergillosis. The clinical and radiological presentation was non-specific and exclusively pulmonary-related. All but one patient had proven or probable/putative IPA. On cerebral computed tomography, lesions appeared as either solitary and hyperdense or were multiple and randomly distributed throughout the brain. One patient presented with sole meningeal infestation. Aspergillus infection was confirmed by brain biopsy in three subjects. Voriconazole was used as primary treatment in only one-half of the patients. Mortality was 90%. ICA is not frequently observed in adult ICU patients. Diagnosis must be considered in patients at risk presenting with proven or probable/putative IPA in association with suggestive neuroradiological findings. The brain is most likely affected through haematogenous dissemination from the lungs. Current treatment recommendations are not always applied and outcome remains dismal.

Invasive infections due to Candida norvegensis and Candida inconspicua: report of 12 cases and review of the literature.

Candida inconspicua and Candida norvegensis are two closely related species rarely involved in invasive infections. The purpose of this study was to depict the epidemiologic and clinical characteristics of candidemia due to these emerging fluconazole less susceptible species. A retrospective analysis of the epidemiology of C. inconspicua and C. norvegensis during the period 2006-2010 was initiated in six French University hospitals. From this, demographics, clinical, diagnostic and therapeutic data of C. inconspicua or C. norvegensis candidemia were recorded and compared to the observations reported in the literature. C. inconspicua was more frequently isolated compared to C. norvegensis (ratio 2.6) but from the same preferential body sites: mainly digestive (56.4% and 48.37%, respectively, for C. inconspicua and C. norvegensis) and respiratory (26% and 28.2%, respectively). Thirteen cases of candidemia were recorded and five additional cases were found in the literature. Hematogical malignancy was the main underlying disease (n = 12). Associated factors were the presence of a vascular catheter (n = 18), broad-spectrum antibiotics (n = 15), and neutropenia (n = 14). In 13 cases (72%), prior colonization was noted before the candidemia diagnosis. Combining the results for the two species, Minimal Inhibitory Concentrations (MIC50) of amphotericin B, fluconazole, voriconazole and caspofungin were 0.125, 48, 0.25, and 0.19 mg/l, respectively. These two species must be added to the growing list of emerging Candida species poorly susceptible to fluconazole.

Impact of the prone position in an animal model of unilateral bacterial pneumonia undergoing mechanical ventilation.

BACKGROUND: The prone position (PP) has proven beneficial in patients with severe lung injury subjected to mechanical ventilation (MV), especially in those with lobar involvement. We assessed the impact of PP on unilateral pneumonia in rabbits subjected to MV. METHODS: After endobronchial challenge with Enterobacter aerogenes, adult rabbits were subjected to either "adverse" (peak inspiratory pressure = 30 cm H2O, zero end-expiratory pressure; n = 10) or "protective" (tidal volume = 8 ml/kg, 5 cm H2O positive end-expiratory pressure; n = 10) MV and then randomly kept supine or turned to the PP. Pneumonia was assessed 8 h later. Data are presented as median (interquartile range). RESULTS: Compared with the supine position, PP was associated with significantly lower bacterial concentrations within the infected lung, even if a "protective" MV was applied (5.93 [0.34] vs. 6.66 [0.86] log10 cfu/g, respectively; P = 0.008). Bacterial concentrations in the spleen were also decreased by the PP if the "adverse" MV was used (3.62 [1.74] vs. 6.55 [3.67] log10 cfu/g, respectively; P = 0.038). In addition, the noninfected lung was less severely injured in the PP group. Finally, lung and systemic inflammation as assessed through interleukin-8 and tumor necrosis factor-α measurement was attenuated by the PP. CONCLUSIONS: The PP could be protective if the host is subjected to MV and unilateral bacterial pneumonia. It improves lung injury even if it is utilized after lung injury has occurred and nonprotective ventilation has been administered.

Mild-stretch mechanical ventilation upregulates toll-like receptor 2 and sensitizes the lung to bacterial lipopeptide.

INTRODUCTION: Mechanical ventilation (MV) could prime the lung toward an inflammatory response if exposed to another insult such as bacterial invasion. The underlying mechanisms are not so far clear. Toll-like receptors (TLRs) allow the host to recognize selectively bacterial pathogens and in turn to trigger an immune response. We therefore hypothesized that MV modulates TLR2 expression and in turn modifies responsiveness to agonists such as bacterial lipopeptide (BLP). METHOD: Both in vitro and in vivo experiments were conducted. First, TLR2 expression and protein were measured in the A549 pulmonary epithelial cell line submitted to 8-hour cyclic stretch (20% elongation; 20/minute rate). After a 24-hour period of cyclic stretch, the inflammatory response of the A549 cells to the synthetic BLP, Pam3CSK4, was tested after 8 hours of exposure. In a second set of experiments, healthy anesthetized and paralyzed rabbits were submitted to 8-hour MV (tidal volume = 12 ml/kg, zero end-expiratory pressure; FIO2 = 50%; respiratory rate = 20/minute) before being sacrificed for TLR2 lung expression assessment. The lung inflammatory response to BLP was then tested in animals submitted to 24-hour MV before being sacrificed 8 hours after the tracheal instillation of Pam3CSK4. RESULTS: Cyclic stretch of human pulmonary epithelial cell lines increased both TLR2 mRNA and protein expression. Cells submitted to cyclic stretch also increased IL-6 and IL-8 secretion in response to Pam3CSK4, a classical TLR2 ligand. A mild-stretch MV protocol induced a 60-fold increase of TLR2 mRNA expression in lung tissue when compared with spontaneously breathing controls. Moreover, the combination of MV and airway exposure to Pam3CSK4 acted synergistically in causing lung inflammation and injury. CONCLUSIONS: Mild-stretch MV increases lung expression of TLR2 and sensitizes the lung to bacterial TLR2 ligands. This may account for the propensity of mechanically ventilated patients to develop acute lung injury in the context of airway bacterial colonization/infection.

Usefulness of the "Candida score" for discriminating between Candida colonization and invasive candidiasis in non-neutropenic critically ill patients: a prospective multicenter study.

OBJECTIVE: To assess the usefulness of the "Candida score" (CS) for discriminating between Candida species colonization and invasive candidiasis (IC) in non-neutropenic critically ill patients. A rate of IC <5% in patients with CS <3 was the primary end point. DESIGN: Prospective, cohort, observational study. SETTING: Thirty-six medical-surgical intensive care units of Spain, Argentina, and France. PATIENTS: A total of 1,107 non-neutropenic adult intensive care unit patients admitted for at least 7 days between April 2006 and June 2007. MEASUREMENTS AND MAIN RESULTS: Clinical data, surveillance cultures for fungal growth, and serum levels of (1-3)-beta-d-glucan and anti-Candida antibodies (in a subset of patients) were recorded. The CS was calculated as follows (variables coded as absent = 0, present = 1): total parenteral nutrition x1, plus surgery x1, plus multifocal Candida colonization x1, plus severe sepsis x2. A CS >or=3 accurately selected patients at high risk for IC. The colonization index was registered if >or=0.5. The rate of IC was 2.3% (95% confidence interval [CI] 1.06-3.54) among patients with CS <3, with a linear association between increasing values of CS and IC rate (p 7 days, with a CS <3 and not receiving antifungal treatment, the rate of IC was <5%. Therefore, IC is highly improbable if a Candida-colonized non-neutropenic critically ill patient has a CS <3.

Cyclic stretch of human lung cells induces an acidification and promotes bacterial growth.

The reasons for bacterial proliferation in the lungs of mechanically ventilated patients are poorly understood. We hypothesized that prolonged cyclic stretch of lung cells influenced bacterial growth. Human alveolar type II-like A549 cells were submitted in vitro to prolonged cyclic stretch. Bacteria were cultured in conditioned supernatants from cells submitted to stretch and from control static cells. Escherichia coli had a marked growth advantage in conditioned supernatants from stretched A549 cells, but also from stretched human bronchial BEAS-2B cells, human MRC-5 fibroblasts, and murine RAW 264.7 macrophages. Stretched cells compared with control static cells acidified the milieu by producing increased amounts of lactic acid. Alkalinization of supernatants from stretched cells blocked E. coli growth. In contrast, acidification of supernatants from control cells stimulated bacterial growth. The effect of various pharmacological inhibitors of metabolic pathways was tested in this system. Treatment of A549 cells and murine RAW 264.7 macrophages with the Na(+)/K(+)-ATPase pump inhibitor ouabain during cyclic stretch blocked both the acidification of the milieu and bacterial growth. Several pathogenic bacteria originating from lungs of patients with ventilator-associated pneumonia (VAP) also grow better in vitro at slightly acidic pH (pH 6-7.2), pH similar to those measured in the airways from ventilated patients. This novel metabolic pathway stimulated by cyclic stretch may represent an important pathogenic mechanism of VAP. Alkalinization of the airways may represent a promising preventive strategy in ventilated critically ill patients.

Candidemia in critically ill patients: difference of outcome between medical and surgical patients.

OBJECTIVE: Candidemia is increasingly encountered in critically ill patients with a high fatality rate. The available data in the critically ill suggest that patients with prior surgery are at a higher risk than others. However, little is known about candidemia in medical settings. The main goal of this study was to compare features of candidemia in critically ill medical and surgical patients. DESIGN: Ten-year retrospective cohort study (1990-2000). SETTING: Medical and surgical intensive care units (ICUs) of a teaching hospital. PATIENTS: Fifty-one patients with at least one positive blood culture for Candida species. MAIN RESULTS: Risk factors were retrieved in all of the patients: central venous catheter (92.1%), mechanical ventilation (72.5%), prior bacterial infection (70.6%), high fungal colonization index (45.6%). Candida albicans accounts for 55% of all candidemia. The overall mortality was 60.8% (85% and 45.2% in medical and surgical patients, respectively). Independent factors associated with survival were prior surgery (hazard ratio [HR] =0.25; 0.09-0.67 95% confidence interval [CI], p<0.05), antifungal treatment (HR =0.11; 0.04-0.30 95% CI, p<0.05) and absence of neutropenia (HR =0.10; 0.02-0.45 95% CI, p<0.05). Steroids, neutropenia and high density of fungal colonization were more frequently found among medical patients compared to surgical ones. CONCLUSIONS: Candidemia occurrence is associated with a high mortality rate among critically ill patients. Differences in underlying conditions could account for the poorer outcome of the medical patients. Screening for fungal colonization could allow identification of such high-risk patients and, in turn, improve outcome.