SERPINE1 and infection: Levels of PAI-1 are increased in infections by several Gram-negative pathogens, including Y. pestis, and are associated with unfavorable outcomes and enhanced mortality (Park et al., 1997; Zeeleder et al., 2006; Song et al., 2007; Comer et al., 2010; Kager et al., 2011; Lim et al., 2011).