title: Interleukin-17A is involved in bacteria-related acute pleural inflammation.
abstract: OBJECTIVE
  The role of pro-inflammatory interleukin-17A (IL-17A), in pleural diseases is unknown. We sought to investigate IL-17A expression and its clinical implications in patients with pleural effusion (PE) and IL-17A involvement in the pathobiology of pleural inflammation elicited by bacterial products.
  
  
  METHODS
  Pleural and blood IL-17A content was examined in 84 patients with PE of different aetiologies, and the diagnostic value of pleural IL-17A was explored in 92 patients with neutrophil-predominant PE. IL-17A contribution in pleural inflammation was evaluated in mice injected intrapleurally with either IL-17A or bacterial products with or without IL-17A-neutralizing antibodies.
  
  
  RESULTS
  IL-17A was upregulated in the pleural space of patients with parapneumonic PE. It was detected in a minority of patients with tuberculous PE and very uncommonly in patients with malignant or other pleural exudates. Pleural fluid (PF) IL-17A levels were correlated with markers of acute pleural inflammation, as well as vascular endothelial growth factor and IL-8 levels. Among patients with neutrophil-predominant PE, PF IL-17A was detected only in those with parapneumonic PE, although the sensitivity of the test was low (<50%). Intrapleural injection of IL-17A elicited a neutrophil-predominant inflammatory response in mice, and IL-17A neutralization partially blocked pleural neutrophilia induced by intrapleural administration of bacterial products.
  
  
  CONCLUSIONS
  IL-17A is involved in pleural inflammation related to bacterial infection. Moreover, pleural IL-17A levels may be helpful in uncovering an infectious aetiology among patients with neutrophil-predominant PE.
authors.affiliation: Applied Biomedical Research and Training Center Marianthi Simou, Department of Critical Care and Pulmonary Services, General Hospital Evangelismos, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Androniki
authors.initials: A
authors.lastname: Kollintza
authors.forename: Sofia
authors.initials: S
authors.lastname: Magkouta
authors.forename: Ioannis
authors.initials: I
authors.lastname: Psallidas
authors.forename: Charalampos
authors.initials: C
authors.lastname: Moschos
authors.forename: Magdalini
authors.initials: M
authors.lastname: Stratiki
authors.forename: Aureli
authors.initials: A
authors.lastname: Esquerda
authors.forename: José M
authors.initials: JM
authors.lastname: Porcel
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kalomenidis
mesh_terms: D000208:Acute Disease; D000818:Animals; D001424:Bacterial Infections / Q000378:metabolism* / Q000382:microbiology; D015415:Biomarkers / Q000378:metabolism; D004195:Disease Models, Animal; D006801:Humans; D020381:Interleukin-17 / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D010996:Pleural Effusion / Q000378:metabolism / Q000382:microbiology; D010998:Pleurisy / Q000378:metabolism* / Q000382:microbiology
chemical_list: D015415:Biomarkers; C508717:IL17A protein, human; D020381:Interleukin-17