SERPINE1 and empyema: While intrapleural levels of PAI-1 in a model of acute, early-stage empyema were higher than those in chronic, advanced-stage empyema (Figure 1, panel (c), A), the efficacy of both IPFT and PAI-1-TFT was markedly lower in treatment of the latter (Figure 2, panel (a); Figure 3; panel (a)) [41].