MMP9 and chorioamnionitis: Interestingly, proteomic comparisons of amniotic fluid samples from women with premature preterm rupture of membranes demonstrated increases in histones (H3, H4, and H2B), myeloperoxidase, neutrophil elastase, and MMP-9 in women with histologic chorioamnionitis and proven intrauterine infection, which likely represents the influx of inflammatory cells into these tissues and potentially the release of extracellular traps (81).