Molecular Profiling of Innate Immune Response Mechanisms in Ventilator-associated Pneumonia.

Ventilator-associated pneumonia (VAP) is a common hospital-acquired infection, leading to high morbidity and mortality. Currently, bronchoalveolar lavage (BAL) is used in hospitals for VAP diagnosis and guiding treatment options. Although BAL collection procedures are invasive, alternatives such as endotracheal aspirates (ETA) may be of diagnostic value, however, their use has not been thoroughly explored. Longitudinal ETA and BAL were collected from 16 intubated patients up to 15 days, of which 11 developed VAP. We conducted a comprehensive LC-MS/MS based proteome and metabolome characterization of longitudinal ETA and BAL to detect host and pathogen responses to VAP infection. We discovered a diverse ETA proteome of the upper airways reflective of a rich and dynamic host-microbe interface. Prior to VAP diagnosis by microbial cultures from BAL, patient ETA presented characteristic signatures of reactive oxygen species and neutrophil degranulation, indicative of neutrophil mediated pathogen processing as a key host response to the VAP infection. Along with an increase in amino acids, this is suggestive of extracellular membrane degradation resulting from proteolytic activity of neutrophil proteases. The metaproteome approach successfully allowed simultaneous detection of pathogen peptides in patients' ETA, which may have potential use in diagnosis. Our findings suggest that ETA may facilitate early mechanistic insights into host-pathogen interactions associated with VAP infection and therefore provide its diagnosis and treatment.

Changes in immune indicators and bacteriologic profile were associated with patients with ventilator-associated pneumonia.

The aim of this study is to explore and identify ventilator-associated pneumonia (VAP)-related prognostic immune factors and further detect the drug-resistant pathogens to establish the theoretical guidance for clinical prevention and treatment strategies of VAP. A total of 478 patients using ventilator who were hospitalized in July 2014 to November 2016 in our hospital were enrolled in this study. About 103 patients with VAP (21.5%, 103/478) among 478 cases of patients using ventilator. Among the 103 patients with VAP, the distribution of pathogenic bacteria and drug resistance in patients with VAP were detected and analyzed. In the VAP group, 35 patients died and 43 patients had simultaneous sepsis. Compared with those of non-VAP group, the proportion of CD3 (P = .012), CD3CD4 (P = .024) and CD8CD28 ( P = .017) T cells in VAP group increased significantly, which indicated more severe immune response. Multivariate regression model analysis revealed that tracheotomy of mechanical ventilation (P = .013), mechanical ventilation time ≥7 days (P = .02) and aspiration and reflux (P = .011) were independent risk factors associated with VAP. According to the results of bacterial culture and drug sensitivity test, rational selection of antibiotics and monitoring of patients within intensive care unit can effectively control the incidence of VAP and improve the prognosis of patients.

The nitric oxide donor, (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NONOate/D-NO), increases survival by attenuating hyperoxia-compromised innate immunity in bacterial clearance in a mouse model of ventilator-associated pneumonia.

Mechanical ventilation (MV) with supraphysiological levels of oxygen (hyperoxia) is a life-saving therapy for the management of patients with respiratory distress. However, a significant number of patients on MV develop ventilator-associated pneumonia (VAP). Previously, we have reported that prolonged exposure to hyperoxia impairs the capacity of macrophages to phagocytize Pseudomonas aeruginosa (PA), which can contribute to the compromised innate immunity in VAP. In this study, we show that the high mortality rate in mice subjected to hyperoxia and PA infection was accompanied by a significant decrease in the airway levels of nitric oxide (NO). Decreased NO levels were found to be, in part, due to a significant reduction in NO release by macrophages upon exposure to PA lipopolysaccharide (LPS). Based on these findings, we postulated that NO supplementation should restore hyperoxia-compromised innate immunity and decrease mortality by increasing the clearance of PA under hyperoxic conditions. To test this hypothesis, cultured macrophages were exposed to hyperoxia (95% O2) in the presence or absence of the NO donor, (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NONOate/D-NO). Interestingly, D-NO (up to 37.5 µM) significantly attenuated hyperoxia-compromised macrophage migratory, phagocytic, and bactericidal function. To determine whether the administration of exogenous NO enhances the host defense in bacteria clearance, C57BL/6 mice were exposed to hyperoxia (99% O2) and intranasally inoculated with PA in the presence or absence of D-NO. D-NO (300 µM-800 µM) significantly increased the survival of mice inoculated with PA under hyperoxic conditions, and significantly decreased bacterial loads in the lung and attenuated lung injury. These results suggest the NO donor, D-NO, can improve the clinical outcomes in VAP by augmenting the innate immunity in bacterial clearance. Thus, provided these results can be extrapolated to humans, NO supplementation may represent a potential therapeutic strategy for preventing and treating patients with VAP.

Alcohol in Traumatic Brain Injury: Toxic or Therapeutic?

BACKGROUND: Alcohol (EtOH) poses a challenge in traumatic brain injuries (TBIs) given its metabolic and neurologic impact. Studies have had opposing results regarding mortality and complication rates in the intoxicated TBI patient. We hypothesized that trauma mechanism, brain injury severity, and blood alcohol concentration (BAC) would influence the impact of EtOH on mortality in TBI. METHODS: We performed a single-institution retrospective review of consecutive adult trauma patients tested for EtOH and a diagnosis of TBI. The primary outcome was mortality, and secondary outcomes included infectious complications. The primary analysis included univariate and multivariate regression comparing mortality between intoxicated and sober patients, at different values of BAC, different brain injury severities, and among mechanisms of trauma. RESULTS: Admission EtOH was assessed in 583 patients with TBI, with 256 testing positive for EtOH and 327 testing negative. Overall, EtOH was associated with lower mortality on univariate analysis (4.7% versus 8.9%, P = 0.05) but not on multivariate analysis (P = 0.21). There was no effect of EtOH on mortality when patients were stratified by brain injury severity or among penetrating trauma victims. However, EtOH was associated with lower overall infectious complications on univariate and multivariate regression. Finally, EtOH was predictive of mortality with an area under the receiver operator characteristic curve of 0.83. CONCLUSIONS: We found that EtOH is not associated with mortality in the patient with TBI, suggesting no causative effect. However, EtOH showed some predictability of mortality based on a receiver operator characteristic analysis. Interestingly, EtOH was associated with lower infectious complications, suggesting an immunomodulatory effect of EtOH in TBI.

Variations of the lung microbiome and immune response in mechanically ventilated surgical patients.

Mechanically ventilated surgical patients have a variety of bacterial flora that are often undetectable by traditional culture methods. The source of infection in many of these patients remains unclear. To address this clinical problem, the microbiome profile and host inflammatory response in bronchoalveolar lavage samples from the surgical intensive care unit were examined relative to clinical pathology diagnoses. The hypothesis was tested that clinical diagnosis of respiratory tract flora were similar to culture positive lavage samples in both microbiome and inflammatory profile. Bronchoalveolar lavage samples were collected in the surgical intensive care unit as standard of care for intubated individuals with a clinical pulmonary infection score of >6 or who were expected to be intubated for >48 hours. Cytokine analysis was conducted with the Bioplex Pro Human Th17 cytokine panel. The microbiome of the samples was sequenced for the 16S rRNA region using the Ion Torrent. Microbiome diversity analysis showed the culture-positive samples had the lowest levels of diversity and culture negative with the highest based upon the Shannon-Wiener index (culture positive: 0.77 ± 0.36, respiratory tract flora: 2.06 ± 0.73, culture negative: 3.97 ± 0.65). Culture-negative samples were not dominated by a single bacterial genera. Lavages classified as respiratory tract flora were more similar to the culture-positive in the microbiome profile. A comparison of cytokine expression between groups showed increased levels of cytokines (IFN-g, IL-17F, IL-1B, IL-31, TNF-a) in culture-positive and respiratory tract flora groups. Culture-positive samples exhibited a more robust immune response and reduced diversity of bacterial genera. Lower cytokine levels in culture-negative samples, despite a greater number of bacterial species, suggest a resident nonpathogenic bacterial community may be indicative of a normal pulmonary environment. Respiratory tract flora samples were most similar to the culture-positive samples and may warrant classification as culture-positive when considering clinical treatment.

Th17 cells are associated with protection from ventilator associated pneumonia.

BACKGROUND: CD4+ T-helper 17 (Th17) cells and Interleukin (IL)-17A play an important role in clearing pathogens in mouse models of pneumonia. We hypothesized that numbers of Th17 cells and levels of IL-17A are associated with risk for nosocomial pneumonia in humans. METHODS: We collected bronchoalveolar lavage (BAL) fluid from mechanically ventilated (n = 25) patients undergoing quantitative bacterial culture to evaluate for ventilator associated pneumonia (VAP). We identified Th17 cells by positive selection of CD4+ cells, stimulation with ionomycin and PMA, then staining for CD4, CD45, CCR6, IL-17A, and IFN-γ followed by flow cytometric analysis (n = 21). We measured inflammatory cytokine levels, including IL-17A, in BAL fluid by immunoassay. RESULTS: VAP was detected in 13 of the 25 subjects. We identified a decreased percentage of IL-17A producing Th17 cells in BAL fluid from patients with VAP compared to those without (p = 0.02). However, we found no significant difference in levels of IL-17A in patients with VAP compared to those without (p = 0.07). Interestingly, IL-17A levels did not correlate with Th17 cell numbers. IL-17A levels did show strong positive correlations with alveolar neutrophil numbers and total protein levels. CONCLUSIONS: Th17 cells are found at lower percentages in BAL fluid from mechanically ventilated patients with VAP and IL-17A levels correlated with Th17 cell percentages in non-VAP subjects, but not those with VAP. These findings suggest that Th17 cells may be protective against development of nosocomial pneumonia in patients receiving mechanical ventilation and that alveolar IL-17A in VAP may be derived from sources other than alveolar Th17 cells.

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.

Fatal coma in a young adult due to late-onset urea cycle deficiency presenting with a prolonged seizure: a case report.

INTRODUCTION: Unexplained hyperammonemic coma in adults can be a medical dilemma in the absence of triggering factors and known comorbidities. Ornithine transcarbamylase deficiency presents most commonly with hyperammonemic coma. Although a rare disorder, ornithine transcarbamylase deficiency is the most common of the urea cycle disorders, which can occur both in children, and less commonly, in adults. The urea cycle disorder is usually acquired as an X-linked trait, and very rarely, similar to our reported case, may be acquired as a "new" mutation. Mutations that lead to later-onset presentations may lead to life-threatening disease and may be unrecognized, particularly when the first clinical symptoms occur in adulthood. CASE PRESENTATION: We report the case of a previously healthy 17-year-old white man who developed a prolonged seizure and a rapid decline in mental status leading to coma over a 3-day period. Analysis of the OTC gene showed a 119G variant, which was identified in exon 2 of the OTC gene by sequencing. CONCLUSIONS: A diagnosis of ornithine transcarbamylase deficiency should be considered in adult patients who present with unexplained hyperammonemic coma and for all adult patients presenting with cryptogenic new-onset seizure and laboratory finding of elevated blood ammonia levels. This reported case highlights the importance of early recognition of this potentially reversible cause of life-threatening encephalopathy, as timely recognition and appropriate treatment can be lifesaving.

Update on ventilator-associated pneumonia.

PURPOSE OF REVIEW: To highlight the importance of escalating pathogen resistance in ventilator-associated pneumonia (VAP) along with diagnostic and treatment implications. RECENT FINDINGS: In a period of rising bacterial resistance, VAP remains an important infection occurring in critically ill patients. Risk factors for multidrug-resistant pathogens depend on both local epidemiology and host factors. New diagnostic techniques and antimicrobials can help with rapid bacterial identification and timely and appropriate treatment while avoiding emergence of bacterial resistance. SUMMARY: Clinicians should be aware of risk factors for multidrug-resistant pathogens causing VAP and also of particularities of diagnosis and treatment of this important clinical entity.

A Detailed Characterization of the Dysfunctional Immunity and Abnormal Myelopoiesis Induced by Severe Shock and Trauma in the Aged.

The elderly are particularly susceptible to trauma, and their outcomes are frequently dismal. Such patients often have complicated clinical courses and ultimately die of infection and sepsis. Recent research has revealed that although elderly subjects have increased baseline inflammation as compared with their younger counterparts, the elderly do not respond to severe infection or injury with an exaggerated inflammatory response. Initial retrospective analysis of clinical data from the Glue Grant trauma database demonstrated that despite a similar frequency, elderly trauma patients have worse outcomes to pneumonia than younger subjects do. Subsequent analysis with a murine trauma model also demonstrated that elderly mice had increased mortality after posttrauma Pseudomonas pneumonia. Blood, bone marrow, and bronchoalveolar lavage sample analyses from juvenile and 20-24-mo-old mice showed that increased mortality to trauma combined with secondary infection in the aged are not due to an exaggerated inflammatory response. Rather, they are due to a failure of bone marrow progenitors, blood neutrophils, and bronchoalveolar lavage cells to initiate and complete an emergency myelopoietic response, engendering myeloid cells that fail to clear secondary infection. In addition, elderly people appeared unable to resolve their inflammatory response to severe injury effectively.

Chronic obstructive pulmonary disease and the risk for ventilator-associated pneumonia.

PURPOSE OF REVIEW: To discuss recent data on the relationship between chronic obstructive pulmonary disease (COPD) and ventilator-associated pneumonia (VAP). RECENT FINDINGS: Despite increased use of noninvasive ventilation, a large proportion of COPD patients still require invasive mechanical ventilation. Intubated COPD patients are at increased risk for VAP compared with patients without COPD. VAP is associated with increased mortality and duration of mechanical ventilation in these patients. Specific risk factors for VAP in this population include prolonged duration of invasive mechanical ventilation, high incidence of microaspiration and bacterial colonization, and altered local and general host defense mechanisms. Skeletal and diaphragmatic muscle weakness resulting from malnutrition, inflammation, and systemic corticosteroids is the main cause for prolonged mechanical ventilation. Increased risk for microaspiration of contaminated secretions is related to gastro-esophageal reflux, and altered interaction between breathing and deglutition. Defective mucociliary clearance contributes to a high incidence of respiratory tract colonization in these patients. Further, increasing evidence suggests that COPD is associated with immunosuppression promoting pulmonary infection. SUMMARY: COPD is a risk factor for VAP. Future studies should focus on specific preventive measures in this population.

Influence of hyperoxia and mechanical ventilation in lung inflammation and diaphragm function in aged versus adult rats.

Although assist ventilation with FIO2 0.21 is the preferable mode of ventilation in the intensive care unit, sometimes controlled ventilation with hyperoxia is needed. But the impact of this setting has not been extensively studied in elderly subjects. We hypothesized that a high fraction of inspired oxygen (FiO(2)) and controlled mechanical ventilation (CMV) is associated with greater deleterious effects in old compared to adult subjects. Adult and old rats were submitted to CMV with low tidal volume (6 ml/kg) and FiO(2) 1 during 3 or 6 h. Arterial blood gas samples were measured at 0, 60 and 180 min (four groups: old and adult rats, 3 or 6 h of CMV), and additionally at 360 min (two groups: old and adult rats, 6 h of CMV). Furthermore, total protein content (TPC) and tumor necrosis factor-alpha (TNF-α) in bronchoalveolar lavage were assessed; lung tissue was used for malondialdehyde and histological analyses, and the diaphragm for measurement of contractile function. Arterial blood gas analysis showed an initial (60 min) greater PaO(2) in elderly versus adult animals; after that time, elderly animals had lowers pH and PaO(2), and greater PaCO(2). After 3 h of CMV, TPC and TNF-α levels were higher in the old compared with the adult group (P < 0.05). After 6 h of MV, malondialdehyde was significantly higher in elderly compared with the adult animals (P < 0.05). Histological analysis showed leukocyte infiltration and edema, greater in old animals. In diaphragm, twitch contraction with caffeine significantly declined after 6 h of CMV only for the elderly group. These data support the hypothesis that relatively short-term CMV with low tidal volume and hyperoxia has greatest impact in elderly rats, decreasing diaphragmatic contractile function and increasing lung inflammation.

Midkine is expressed and differentially processed during chronic obstructive pulmonary disease exacerbations and ventilator-associated pneumonia associated with Staphylococcus aureus infection.

Staphylococcus aureus is sometimes isolated from the airways during acute exacerbations of chronic obstructive pulmonary disease (COPD) but more commonly recognized as a cause of ventilator-associated pneumonia (VAP). Antimicrobial proteins, among them midkine (MK), are an important part of innate immunity in the airways. In this study, the levels and possible processing of MK in relation to S. aureus infection of the airways were investigated, comparing COPD and VAP, thus comparing a state of disease with preceding chronic inflammation and remodeling (COPD) with acute inflammation (that is, VAP). MK was detected in the small airways and alveoli of COPD lung tissue but less so in normal lung tissue. MK at below micromolar concentrations killed S. aureus in vitro. Proteolytic processing of MK by the staphylococcal metalloprotease aureolysin (AL), but not cysteine protease staphopain A (SA), resulted in impaired bactericidal activity. Degradation was seen foremost in the COOH-terminal portion of the molecule that harbors high bactericidal activity. In addition, MK was detected in sputum from patients suffering from VAP caused by S. aureus but less so in sputum from COPD exacerbations associated with the same bacterium. Recombinant MK was degraded more rapidly in sputum from the COPD patients than from the VAP patients and a greater proteolytic activity in COPD sputum was confirmed by zymography. Taken together, proteases of both bacteria and the host contribute to degradation of the antibacterial protein MK, resulting in an impaired defense of the airways, in particular, in COPD where the state of chronic inflammation could be of importance.

High Mobility Group Box-1 mediates hyperoxia-induced impairment of Pseudomonas aeruginosa clearance and inflammatory lung injury in mice.

Mechanical ventilation with supraphysiological concentrations of oxygen (hyperoxia) is routinely used to treat patients with respiratory distress. However, a significant number of patients on ventilators exhibit enhanced susceptibility to infections and develop ventilator-associated pneumonia (VAP). Pseudomonas aeruginosa (PA) is one of the most common species of bacteria found in these patients. Previously, we demonstrated that prolonged exposure to hyperoxia can compromise the ability of alveolar macrophages (AMs), an essential part of the innate immunity, to phagocytose PA. This study sought to investigate the potential molecular mechanisms underlying hyperoxia-compromised innate immunity against bacterial infection in a murine model of PA pneumonia. Here, we show that exposure to hyperoxia (≥ 99% O2) led to a significant elevation in concentrations of airway high mobility group box-1 (HMGB1) and increased mortality in C57BL/6 mice infected with PA. Treatment of these mice with a neutralizing anti-HMGB1 monoclonal antibody (mAb) resulted in a reduction in bacterial counts, injury, and numbers of neutrophils in the lungs, and an increase in leukocyte phagocytic activity compared with mice receiving control mAb. This improved phagocytic function was associated with reduced concentrations of airway HMGB1. The correlation between phagocytic activity and concentrations of extracellular HMGB1 was also observed in cultured macrophages. These results indicate a pathogenic role for HMGB1 in hyperoxia-induced impairment with regard to a host's ability to clear bacteria and inflammatory lung injury. Thus, HMGB1 may provide a novel molecular target for improving hyperoxia-compromised innate immunity in patients with VAP.

An in vitro model of mycobacterial granuloma to investigate the immune response in brain-injured patients.

OBJECTIVE: We investigated the overall immune response to pathogens in brain-injured patients, and assessed its relationship to nosocomial pneumonia. DESIGN: Observational study. SETTING: Two surgical ICUs of a single institution. PATIENTS: Severe brain-injured patients (n = 32) requiring mechanical ventilation and sex- and age-matched healthy donors (n = 25). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We evaluated, ex vivo, the ability of peripheral blood mononuclear cells from brain injury patients to develop an effective granulomatous response to mycobacteria. Thirty-two consecutive patients (25 traumatic brain injured and seven subarachnoid hemorrhage) were included. Median Glasgow Coma Scale was 7 (5-8). Thirteen (41%) patients developed nosocomial pneumonia. Peripheral blood mononuclear cells from brain-injured patients with nosocomial pneumonia generated significantly fewer mature granulomas compared with brain-injured patients without nosocomial pneumonia and with healthy donors. The percentage of multinucleated giant cells was lower in brain-injured patients without nosocomial pneumonia (1% [range: 0%-7%]) and in brain-injured patients with nosocomial pneumonia (4% [range: 2%-5%]) compared with healthy donors (20% [range: 15%-28%]). The blood levels of γδ T cells were significantly increased in brain-injured patients without nosocomial pneumonia (66% [range: 34%-69%]) compared with healthy donors (23% [range: 8%-61%]) and was not altered in brain-injured patients with nosocomial pneumonia (31% [range: 12%-44%]). The percentage of γδ T cells in granulomas was significantly decreased in brain injury patients with nosocomial pneumonia (5% [range: 4%-43%]) compared with healthy donors (43% [range: 19%-54%]) and was not significantly altered in brain-injured patients without nosocomial pneumonia (26% [range: 10%-41%]). The blood levels of natural killer cells were not altered in brain-injured patients. The percentage of natural killer cells in granulomas was significantly decreased in brain-injured patients with nosocomial pneumonia (3% [range: 1%-9%]) compared with brain-injured patients without nosocomial pneumonia (16% [range: 6%-29%]) and with healthy donors (17% [range: 10%-29%]). CONCLUSIONS: Brain-injured patients experienced a maturation defect of the ex vivo granulomatous response involving monocytes as well as natural killer cells and γδ T cells.

The role of total bile acid in oral secretions in ventilator-associated pneumonia.

PURPOSE: The aim of this study was to investigate the role of inflammatory biomarkers and total bile acid (TBA) in oral secretions in the development of ventilator-associated pneumonia (VAP). MATERIALS: This prospective study was conducted in an intensive care unit. Oral secretions were collected from mechanically ventilated patients who met the selection criteria for VAP prevention protocol. The levels of interleukin (IL)-1ß, IL-6, IL-8, tumor necrosis factor α, soluble intercellular adhesion molecule-1, monocyte chemoattractant protein-1, C-reactive protein, surfactant protein D, and TBA in oral secretions were measured and compared between the patients with and those without VAP. RESULTS: Thirty-nine patients with and 39 patients without VAP were studied. The levels of inflammatory biomarkers in oral secretions showed no significant difference between the 2 groups. However, the patients with VAP had significantly higher values of TBA in oral secretions than did those without VAP (median and 25th-75th interquartile range, 9.59 and 1.37-24.66 µmol/L vs 2.74 and 0.00-8.22 µmol/L; P < .003). No significant correlations were found between TBA and inflammatory biomarkers in oral secretions. CONCLUSIONS: Duodenogastroesophageal reflux as evidenced by the presence of TBA in oral secretions is common in mechanically ventilated patients and may play a role in the development of VAP.

Severe traumatic head injury affects systemic cytokine expression.

BACKGROUND: The neuroimmunologic effect of traumatic head injury remains ill-defined. This study aimed to characterize systemic cytokine profiles among traumatically injured patients to assess the effect of traumatic head injury on the systemic inflammatory response. STUDY DESIGN: For 5 years, 1,022 patients were evaluated from a multi-institutional Trauma Immunomodulatory Database. Patients were stratified by presence of severe head injury (SHI; head Injury Severity Score ≥4, n = 335) vs nonsevere head injury (NHI; head Injury Severity Score ≤3, n = 687). Systemic cytokine expression was quantified by ELISA within 72 hours of admission. Patient factors, outcomes, and cytokine profiles were compared by univariate analyses. RESULTS: SHI patients were more severely injured with higher mortality, despite similar ICU infection and ventilator-associated pneumonia rates. Expression of early proinflammatory cytokines, interleukin-6 (p < 0.001) and tumor necrosis factor-α (p = 0.02), was higher among NHI patients, and expression of immunomodulatory cytokines, interferon-γ (p = 0.01) and interleukin-12 (p = 0.003), was higher in SHI patients. High tumor necrosis factor-α levels in NHI patients were associated with mortality (p = 0.01), increased mechanical ventilation (p = 0.02), and development of ventilator-associated pneumonia (p = 0.01). Alternatively, among SHI patients, high interleukin-2 levels were associated with survival, decreased mechanical ventilation, and absence of ventilator-associated pneumonia. CONCLUSIONS: The presence of severe traumatic head injury significantly alters systemic cytokine expression and exerts an immunomodulatory effect. Early recognition of these profiles can allow for targeted intervention to reduce patient morbidity and mortality.

Liposome-encapsulated dexamethasone attenuates ventilator-induced lung inflammation.

BACKGROUND AND PURPOSE: Systemic glucocorticoid therapy may effectively attenuate lung inflammation but also induce severe side-effects. Delivery of glucocorticoids by liposomes could therefore be beneficial. We investigated if liposome-encapsulated dexamethasone inhibited ventilator-induced lung inflammation. Furthermore, we evaluated whether targeting of cellular Fcγ-receptors (FcγRs) by conjugating immunoglobulin G (IgG) to liposomes, would improve the efficacy of dexamethasone-liposomes in attenuating granulocyte infiltration, one of the hallmarks of lung inflammation. EXPERIMENTAL APPROACH: Mice were anaesthetized, tracheotomized and mechanically ventilated for 5 h with either 'low' tidal volumes ∼7.5 mL·kg(-1) (LV(T) ) or 'high' tidal volumes ∼15 mL·kg(-1) (HV(T) ). At initiation of ventilation, we intravenously administered dexamethasone encapsulated in liposomes (Dex-liposomes), dexamethasone encapsulated in IgG-modified liposomes (IgG-Dex-liposomes) or free dexamethasone. Non-ventilated mice served as controls. KEY RESULTS: Dex-liposomes attenuated granulocyte infiltration and IL-6 mRNA expression after LV(T) -ventilation, but not after HV(T) -ventilation. Dex-liposomes also down-regulated mRNA expression of IL-1ß and KC, but not of CCL2 (MCP-1) in lungs of LV(T) and HV(T) -ventilated mice. Importantly, IgG-Dex-liposomes inhibited granulocyte influx caused by either LV(T) or HV(T) -ventilation. IgG-Dex-liposomes diminished IL-1ß and KC mRNA expression in both ventilation groups, and IL-6 and CCL2 mRNA expression in the LV(T) -ventilated group. Free dexamethasone prevented granulocyte influx and inflammatory mediator expression induced by LV(T) or HV(T) -ventilation. CONCLUSIONS AND IMPLICATIONS: FcγR-targeted IgG-Dex-liposomes are pharmacologically more effective than Dex-liposomes particularly in inhibiting pulmonary granulocyte infiltration. IgG-Dex-liposomes inhibited most parameters of ventilator-induced lung inflammation as effectively as free dexamethasone, with the advantage that liposome-encapsulated dexamethasone will be released locally in the lung thereby preventing systemic side-effects.

Proinflammatory cytokine surge after injury stimulates an airway immunoglobulin a increase.

BACKGROUND: : Injury stimulates an innate airway IgA response in severely injured patients, which also occurs in mice. Tumor necrosis factor (TNF)-α and interleukin (IL)-1ß stimulate the production of polymeric immunoglobulin receptor, the protein required to transport immunoglobulin A (IgA) to mucosal surfaces. Blockade of TNF-α and IL-1ß eliminates the airway IgA response to injury. IL-6 stimulates differentiation of B cells into IgA-secreting plasma cells at mucosal sites. We investigated the local and systemic kinetics of TNF-α, IL-1ß, and IL-6 after injury in mice. We also hypothesized that injection of exogenous TNF-α, IL-1ß, and IL-6 would replicate the airway IgA response to injury. METHODS: : Experiment 1: male Institute of Cancer Research mice were randomized to uninjured controls (n = 8) or to surgical stress with laparotomy and neck incisions, with killing at 1, 2, 3, 5, or 8 hours after injury (n = 8/group). Bronchoalveolar lavage (BAL) and serum levels of TNF-α, IL-1ß, and IL-6 were analyzed by enzyme-linked immunosorbent assay. Experiment 2: male Institute of Cancer Research mice were randomized to uninjured controls (n = 6), injury (surgical stress that was similar to experiment 1 except the peritoneum was left intact, n = 6), or cytokine injection with intraperitoneal injection of recombinant TNF-α, IL-1ß, and IL-6. Animals were killed at 2 hours after injury, and nasal airway lavage and BAL IgA were analyzed by enzyme-linked immunosorbent assay. RESULTS: : Experiment 1: BAL TNF-α, IL-1ß, and IL-6 levels increased in bimodal pattern after injury at 3 hours and 8 hours versus controls (p < 0.05). Serum IL-6 did not increase at 3 hours, but did show a significant increase by 5 hours versus control (p < 0.05). Serum levels of TNF-α and IL-1ß did not change. Experiment 2: both Injury and combination TNF-α, IL-1ß, and IL-6 cytokine injection significantly increased IgA levels in airway lavage (BAL + nasal airway lavage) compared with control (p < 0.01 for both). CONCLUSIONS: : Airway levels of TNF-α, IL-1ß, and IL-6 increase in a bimodal pattern after injury with peaks at 3 hours and 8 hours, which do not correspond to serum changes. The peak at 8 hours is consistent with the known increase in airway IgA after injury. Intraperitoneal injection of a combination exogenous TNF-α, IL-1ß, and IL-6 replicates the airway IgA increase after injury. This effect is not seen with individual cytokine injections.