Ruth MacRedmond

Epithelial expression of TLR4 is modulated in COPD and by steroids, salmeterol and cigarette smoke

The toll-like receptors (TLRs) are a key component of host defense in the respiratory epithelium. Cigarette smoking is associated with increased susceptibility to infection, while COPD is characterised by bacterial colonisation and infective exacerbations. We found reduced TLR4 gene expression in the nasal epithelium of smokers compared with non-smoking controls, while TLR2 expression was unchanged. Severe COPD was associated with reduced TLR4 expression compared to less severe disease, with good correlation between nasal and tracheal expression. We went on to examine the effect of potential modulators of TLR4 expression in respiratory epithelium pertinent to airways disease. Using an airway epithelial cell line, we found a dose-dependent downregulation in TLR4 mRNA and protein expression by stimulation with cigarette smoke extracts. Treatment with the corticosteroids fluticasone and dexamethasone resulted in a dose-dependent reduction in TLR4 mRNA and protein. The functional significance of this effect was demonstrated by impaired IL-8 and HBD2 induction in response to LPS. Stimulation with salmeterol (10-6 M) caused upregulation of TLR4 membrane protein presentation with no upregulation of mRNA, suggesting a post-translational effect. The effect of dexamethasone and salmeterol in combination was additive, with downregulation of TLR4 gene expression, and no change in membrane receptor expression. Modulation of TLR4 in respiratory epithelium may have important implications for airway inflammation and infection in response to inhaled pathogens.

Respiratory epithelial cells require Toll-like receptor 4 for induction of Human β-defensin 2 by Lipopolysaccharide

BackgroundThe respiratory epithelium is a major portal of entry for pathogens and employs innate defense mechanisms to prevent colonization and infection. Induced expression of human β-defensin 2 (HBD2) represents a direct response by the epithelium to potential infection. Here we provide evidence for the critical role of Toll-like receptor 4 (TLR4) in lipopolysaccharide (LPS)-induced HBD2 expression by human A549 epithelial cells.MethodsUsing RTPCR, fluorescence microscopy, ELISA and luciferase reporter gene assays we quantified interleukin-8, TLR4 and HBD2 expression in unstimulated or agonist-treated A549 and/or HEK293 cells. We also assessed the effect of over expressing wild type and/or mutant TLR4, MyD88 and/or Mal transgenes on LPS-induced HBD2 expression in these cells.ResultsWe demonstrate that A549 cells express TLR4 on their surface and respond directly to Pseudomonas LPS with increased HBD2 gene and protein expression. These effects are blocked by a TLR4 neutralizing antibody or functionally inactive TLR4, MyD88 and/or Mal transgenes. We further implicate TLR4 in LPS-induced HBD2 production by demonstrating HBD2 expression in LPS non-responsive HEK293 cells transfected with a TLR4 expression plasmid.ConclusionThis data defines an additional role for TLR4 in the host defense in the lung.

Limited echocardiography–guided therapy in subacute shock is associated with change in management and improved outcomes

PURPOSE The purpose of the study was to compare the effect of limited echocardiography (LE)-guided therapy to standard management on 28-day mortality, intravenous fluid prescription, and inotropic dosing following early resuscitation for shock. MATERIALS AND METHODS Two hundred twenty critically ill patients with undifferentiated shock from a quaternary intensive care unit were included in the study. The LE group consisted of 110 consecutive patients prospectively studied over a 12-month period receiving LE-guided management. The standard management group consisted of 110 consecutive patients retrospectively studied with shock immediately prior to the LE intervention. RESULTS In the LE group, fluid restriction was recommended in 71 (65%) patients and initiation of dobutamine in 27 (25%). Fluid prescription during the first 24 hours was significantly lower in LE patients (49 [33-74] vs 66 [42-100] mL/kg, P = .01), whereas 55% more LE patients received dobutamine (22% vs 12%, P = .01). The LE patients had improved 28-day survival (66% vs 56%, P = .04), a reduction in stage 3 acute kidney injury (20% vs 39%), and more days alive and free of renal support (28 [9.7-28] vs 25 [5-28], P = .04). CONCLUSIONS Limited echocardiography-guided management following early resuscitation is associated with improved survival, less fluid, and increased inotropic prescription. A prospective randomized control trial is required to verify these results.

Conjugated linoleic acid improves airway hyper-reactivity in overweight mild asthmatics.

Background Conjugated linoleic acids (CLA) are naturally occurring fatty acids that have multiple biological properties including the regulation of metabolic, proliferative and immune processes.

Community-acquired pneumonia in older patients: does age influence systemic cytokine levels in community-acquired pneumonia?

Background and objective:  Community‐acquired pneumonia (CAP) is a major cause of death in the elderly. The age‐related increase in comorbid illnesses plays a part but the effect of aging on the immune response may be equally important. We aimed to evaluate patients with CAP for evidence of a muted response to infection in elderly patients admitted to hospital compared with a younger patient group.

INTERLEUKIN-9 AND -13 INHIBIT SPONTANEOUS AND CORTICOSTEROID INDUCED APOPTOSIS OF NORMAL AIRWAY EPITHELIAL CELLS

The airway epithelium is the target of physical and allergic insults. The resulting inflammatory signals from Th2 cytokines including interleukin (IL)-9 and IL-13 have pleiotropic activities and have been implicated in airway remodeling in asthmatics. The objective of this study was to determine the role of IL-9 and IL-13 in the regulation of normal airway epithelial cell death and epithelial repair. In a cell culture model, a normal human airway epithelial cell line and primary airway epithelial cells were treated with IL-9 or IL-13 alone and in combination. Apoptosis was determined by multiple techniques, including enrichment of nucleosomes released into the cytoplasm, mitochondrial membrane polarity perturbation, cytosolic cytochrome c released and the detection of cleaved p85-poly(ADP-ribose)polymerase (PARP). Proliferation was quantified by BrdU incorporation. IL-9 and IL-13 treatment, alone and in combination, resulted in a significant reduction in spontaneous airway epithelial cell apoptosis when compared to controls. The cytoprotective effect of IL-9 was associated with up-regulation of the antiapoptotic molecule Bcl-2. IL-13 also demonstrated coordinate pro-proliferative activity .Dexamethasone induces apoptosis in airway epithelial cells. Coincubation with IL-9 or IL-13 was protective against this corticosteroid-induced apoptosis by up-regulation of Bcl-2. These data demonstrate that IL-9 and IL-13 may be critical to normal cellular homeostasis in the setting of airway epithelial injury. A dysregulated response to these cytokines may contribute to airway remodeling in asthma.

Conjugated linoleic acid (CLA): Is it time to supplement asthma therapy?

The limitations and side effects of existing asthma therapies prompt interest in complementary and alternative therapies. Conjugated linoleic acids (CLA) are a family of natural fatty acids found primarily in beef and dairy products. These molecules have a variety of biological properties which suggest potential benefit in asthma, including effects on energy regulation, lipid metabolism, inflammation and immune function. Here we review the evidence for these effects from pre-clinical and clinical studies, their significance in the context of human asthma, and discuss the potential role for CLA supplementation in asthma management.

Fluticasone Induces Epithelial Injury and Alters Barrier Function in Normal Subjects

Objective The airway epithelium has a number of roles pivotal to the pathogenesis of asthma, including provision of a physical and immune barrier to the inhaled environment. Dysregulated injury and repair responses in asthma result in loss of airway epithelial integrity. Inhaled corticosteroids are a corner stone of asthma treatment. While effective in controlling asthma symptoms, they fail to prevent airway remodeling. Direct cytopathic effects on the airway epithelium may contribute to this. Methods This study examined the effects of a 4-week treatment regimen of inhaled fluticasone 500 μg twice daily in healthy human subjects. Induced sputum was collected for cell counts and markers of inflammation. Barrier function was examined by diethylenetriaminepentacetic acid (DTPA) clearance measured by nuclear scintillation scan, and albumin concentration in induced sputum. Results Steroid exposure resulted in epithelial injury as measured by a significant increase in the number of airway epithelial cells in induced sputum. There was no change in airway inflammation by induced sputum inflammatory cell counts or cytokine levels. Epithelial shedding was associated with an increase in barrier function, as measured by both a decrease in DTPA clearance and decreased albumin in induced sputum. This likely reflects the normal repair response. Conclusion Inhaled corticosteroids cause injury to normal airway epithelium. These effects warrant further evaluation in asthma, where the dysregulated repair response may contribute to airway remodeling.

IL-13Rα2/AP-1 complex signalling mediates airway epithelial repair without effects on remodeling pathways

Objective/purpose The airway epithelium serves as a physical defense barrier to the external environment for the underlying tissue and suffers frequent injury. The response to injury is inflammation followed by debris clearance and repair. Although IL-13 is known to be a key cytokine in mediating inflammatory and remodeling responses via signal transducer and activator of transcription 6 (STAT6) and early growth response protein 1 (Egr1), our laboratory has demonstrated that IL-13 is critical to airway epithelial repair via the release of heparin-binding epidermal growth factor (HB-EGF) and activation of epidermal growth factor receptor (EGFR). IL-13 signals through two receptors, IL-13Ra1/IL-4R and IL-13Ra2. IL-13Ra2 has previously been thought to act exclusively as a decoy receptor, however our findings show that IL13Ra2 can act as a signaling receptor and is involved in mediating airway epithelial repair. Differential signaling via IL-13Ra1 or IL-13Ra2 may determine a remodeling versus repair response to injury in airway epithelium.

A comprehensive regional clinical and educational ECPR protocol decreases time to ECMO in patients with refractory out-of-hospital cardiac arrest

OBJECTIVE Extracorporeal membrane oxygenation within CPR (ECPR) may improve survival for refractory out-of-hospital cardiac arrest (OHCA). We developed a prehospital, emergency department (ED), and hospital-based clinical and educational protocol to improve the key variable of time-to-ECPR (TTE). METHODS In a single urban health region we involved key prehospital, clinical, and administrative stakeholders over a 2-year period, to develop a regional ECPR program with destination to a single urban tertiary care hospital. We developed clear and reproducible inclusion criteria and processes, including measures of program efficiency. We conducted seminars and teaching modules to paramedics and hospital-based clinicians including monthly simulator sessions, and performed detailed reviews of each treated case in the form of report cards. In this before-and-after study we compared patients with ECPR attempted prior to, and after, protocol implementation. The primary outcome was TTE, defined as the time of initial professional CPR to establishment of extracorporeal circulation. We compared the median TTE for patients in the two groups using the Wilcoxon signed rank test. RESULTS Four patients were identified prior to the protocol and managed in an ad hoc basis; for nine patients the protocol was utilized. Overall favourable neurological outcomes among ECPR-treated patients were 27%. The median TTE was 136 minutes (IQR 98 - 196) in the pre-protocol group, and 60 minutes (IQR 49 - 81) minutes in the protocol group (p=0.0165). CONCLUSION An organized clinical and educational protocol to initiate ECPR for patients with OHCA is feasible and significantly reduces the key benchmark of time-to-ECPR flows.