lipoteichoic-acid and Pleural-Effusion

Parapneumonic effusion (PPE) is commonly caused by Gram-positive bacteria (GPB) and often presents with pleural loculation, which is characterized by overproduction of plasminogen activator inhibitor (PAI)-1. Lipoteichoic acid (LTA), a surface adhesion molecule of GPB, binds to the pleural mesothelium and triggers inflammation. However, the effects of LTA on PAI-1 expression in PPE and underlying mechanisms remain unclear.. Thirty consecutive patients with PPE were enrolled, including uncomplicated culture negative (CN, n = 11), Gram-negative bacteria (GNB, n = 7) and GPB (n = 12) groups stratified by pleural fluid characteristics and bacteriology, and the effusion PAI-1 levels were measured. In addition, human pleural mesothelial cells (PMC) were treated with LTA and the expression of PAI-1 and activation of signalling pathways were assayed.. The median levels of PAI-1 were significantly higher in GPB (160.5 ng/mL) and GNB (117.0 ng/mL) groups than in the uncomplicated CN (58.0 ng/mL) group. In human PMC, LTA markedly upregulated PAI-1 mRNA and protein expression and enhanced elaboration of Toll-like receptor 2 (TLR2). Furthermore, LTA increased c-Jun N-terminal kinase (JNK) phosphorylation, induced activating transcription factor 2 (ATF2)/c-Jun nuclear translocation and activated PAI-1 promoter activity. Pretreatment with TLR2 siRNA significantly inhibited LTA-induced JNK phosphorylation and PAI-1 protein expression.. Culture-positive PPE, especially that caused by GPB, has a significantly higher level of PAI-1 than uncomplicated CN PPE. LTA upregulates PAI-1 expression through activation of TLR2/JNK/activator protein 1 (AP-1) pathway in human PMC. Better understanding of the modulation of PAI-1 synthesis by LTA in PPE may provide potential therapies for infected pleural effusions.

Topics: Activating Transcription Factor 2; Adult; Aged; Aged, 80 and over; Cell Culture Techniques; Epithelial Cells; Female; Gram-Negative Bacteria; Gram-Positive Bacteria; Humans; JNK Mitogen-Activated Protein Kinases; Lipopolysaccharides; Male; Middle Aged; Phosphorylation; Plasminogen Activator Inhibitor 1; Pleura; Pleural Effusion; RNA, Messenger; Signal Transduction; Teichoic Acids; Toll-Like Receptor 2; Transcription Factor AP-1; Up-Regulation