Parapneumonic Effusions Are Characterized by Elevated Levels of Neutrophil Extracellular Traps.

BACKGROUND: Neutrophil extracellular traps (NETs) increasingly are implicated in acute and chronic conditions involving multiple organ systems. RESEARCH QUESTION: Are NET concentrations higher in parapneumonic effusions compared with effusions of other origin and does this reflect the inflammatory nature of these effusions? STUDY DESIGN AND METHODS: Patients (N = 101) seeking hospital treatment for undifferentiated pleural effusion underwent pleural fluid classification based on cytologic analysis results, biochemical findings, microbiological characteristics, and clinical judgement. Concentrations of NET markers (extracellular DNA [eDNA], citrullinated histone H3 [citH3]), neutrophils (α-defensins), and inflammation (IL-1ß)-related proteins were quantified by enzyme-linked immunosorbent assay. Differences between groups were analyzed using the Kruskal-Wallis one-way analysis of variance. Correlations used Spearman coefficient. Receiver operating characteristic (ROC) curves were calculated. RESULTS: Effusions were classified into four groups: parapneumonic (n = 18), malignant (n = 35), transudative (n = 22), and unclassifiable (n = 26). Concentrations of NETs markers were significantly higher in the parapneumonic group compared with malignant, transudative, and unclassifiable groups (median eDNA, 12.8 ng/mL vs 0.77 ng/mL, 0.44 ng/mL, and 0.86 ng/mL [P < .001]; and median citH3, 127.1 ng/mL vs 0.44 ng/mL, 0.34 ng/mL, and 0.49 ng/mL [P < .001]). citH3 and eDNA were correlated highly with lactate dehydrogenase (LDH; Spearman r = 0.66 and r = 0.73, respectively; P < .001) and moderately negatively correlated with pH (r = -0.55 and r = -0.62, respectively; P < .001). α-Defensins and IL-1ß were higher in the parapneumonic group than in other groups (median α-defensins, 124.4 ng/mL vs 4.7 ng/mL,7 ng/mL, and 6.9 ng/mL [P < .001]; and median IL-1ß, 145 pg/mL vs 1.87 pg/mL, 1.39 pg/mL, and 2.6 pg/mL [P < .001]) and moderately correlated with LDH (r = 0.60 and r = 0.57; P < .001). ROC curves showed high sensitivity and specificity for NET markers for prediction of parapneumonic effusion. INTERPRETATION: High levels of some NET-related mediators in parapneumonic effusions correlate with inflammation. Effusions of other causes do not show high levels of NETs. These results may have treatment implications because NETs may be an important contributor to the inflammation and viscosity of parapneumonic effusions and may help us to understand the therapeutic benefit of deoxyribonuclease in empyema.

The Emerging Role of Neutrophil Extracellular Traps in Respiratory Disease.

Neutrophil extracellular traps (NETs) are extrusions of intracellular DNA and attached granular material that enable bacterial killing. NETs are increasingly recognized for their role in the pathogenesis of respiratory disease. NETs are composed of a complex mix of intracellularly derived material that neutrophils organize within the cytoplasm and then expel in a nondirected manner in the vicinity of invading organisms. Combined, these trap and destroy multiple genera of microbes including bacteria, fungi, viruses, and protozoans, limiting infection especially where phagocytosis is not possible. At first, NET formation was thought to be a terminal event for neutrophils; however, it is now apparent that some neutrophils survive this process, becoming anuclear, and may drive ongoing tissue damage. NETs are now known to be directly cytotoxic to lung epithelium and endothelium, and their excessive production is seen in pneumonia and acute lung injury as well as several chronic diseases, including COPD, asthma, and cystic fibrosis. NETs also appear to play a role in both tumor defense and dissemination, depending on the local microenvironment and the specific tumor subtype. It is becoming increasingly apparent that NET formation can exert a positive or negative influence on multiple respiratory pathologies and that simply globally reducing or increasing NET formation is unlikely to be a therapeutic success. Rather, as our understanding grows, it is likely that targeted NET up- or downregulation along with destruction or protection of already formed NETs may become an additional point of intervention for respiratory physicians.

Thoracic Ultrasound: What Non-radiologists Need to Know.

PURPOSE OF REVIEW: The aim of this review is to provide the theoretical and practical knowledge essential for non-radiologists to develop the skills necessary to apply thoracic ultrasound as an extension of clinical assessment and intervention. RECENT FINDINGS: Issues relating to training and competence are discussed and a library of thoracic ultrasound videos is provided to illustrate artefacts, pleural, parenchymal and pneumothorax pathology as well as important pitfalls to consider. Novel and future diagnostic applications of thoracic ultrasound in the setting of acute cardiorespiratory pathology including consolidation, acute interstitial syndromes and pulmonary embolism are explored. SUMMARY: Thoracic ultrasound requires an understanding of imaging artefact specific to lung and pleura and a working knowledge of machine knobology for image optimisation and interpretation. Ultrasound is a valuable tool for the practicing chest clinician providing diagnostic information for the assessment of pleural and parenchymal disease and increased safety and cost effectiveness of thoracic interventions.

Thoracic ultrasound recognition of competence: A position paper of the Thoracic Society of Australia and New Zealand.

The ability to perform bedside thoracic ultrasound is increasingly recognized as an essential skill for thoracic clinicians, extending the clinical examination and aiding diagnostic and therapeutic procedures. Thoracic ultrasound reduces complications and increases success rates when used prior to thoracentesis or intercostal chest tube insertion. It is increasingly difficult to defend performing these procedures without real or near-real time image guidance. To assist thoracic physicians and others achieve and demonstrate thoracic ultrasound competence, the Interventional Pulmonology Special Interest Group (IP-SIG) of the Thoracic Society of Australia and New Zealand (TSANZ) has developed a new pathway with four components: (i) completion of an approved thoracic ultrasound theory and hands-on teaching course. (ii) A log of at least 40 relevant scans. (iii) Two formative assessments (following 5-10 scans and again after 20 scans) using the Ultrasound-Guided Thoracentesis Skills and Tasks Assessment Tool (UG-STAT). (iv) A barrier assessment (UG-STAT, pass score of 90%) by an accredited assessor not directly involved in the candidate's training. Upon completion of these requirements a candidate may apply to the TSANZ for recognition of competence. This pathway is intended to provide a regional standard for thoracic ultrasound training.