Biomarker Levels During Indwelling Pleural cAtheter Sample Testing

An alternative and emerging treatment for malignant pleural effusions is the placement of a chronic indwelling pleural catheter. Tunneled pleural catheters (TPC) are ideal for treatment of malignant pleural effusion (MPE) associated with a trapped or non-expandable lung which will not have sufficient visceral and parietal pleura apposition for chemical pleurodesis. Transforming growth factor-Beta 1 (TGF-β) is a profibrotic cytokine, and a potent inducer of Plasminogen activator inhibitor-1 (PAI-1) in human pleural mesothelial cells. PAI-1 inhibits protease-dependent fibrinolytic activity and along with TGF-β, its concentration is increased in exudative and tuberculous pleural effusion. TGF-β levels in pleural fluid have been shown to correlate with pleural thickness in tuberculosis pleurisy and empyema in rabbits. TGF-β is a multifunctional cytokine primarily produced by mesothelial cells in the pleural space, but can also originate from lung parenchymal macrophages that migrate to the pleural space. In humans, TGF-β consists of three isoforms (TGF-β1, TGF-β2, and TGF-β3). They share many biological activities and their actions on cells are qualitatively similar in most cases. TGF-β stimulates the extracellular matrix production and studies support that TGF-β over-production is a key regulator in pleural fibrosis and chemical pleurodesis. Moreover, TGF-β signaling for the production of PAI-1 is clearly noted in human mesothelial cells of different origins. Different inflammatory stimuli in the pleural space including malignancy and infection may activate TGF-β up-regulation and enhanced production which in turns results in PAI-1 expression.