Nuclear Factor Kappa B Regulation of Proinflammatory Cytokines in Human Gestational Tissues in Vitro

Proinflammatory cytokines are implicated in the initiation and progression of human labor and delivery, particularly in relation to infection-induced preterm labor. In nongestational tissues, the nuclear factor kappa B (NF-kappaB) transcription pathway is a key regulator of proinflammatory cytokine release. In these tissues, sulfasalazine (SASP), through its ability to inhibit NF-kappaB activation, inhibits release of interleukin (IL)-2, IL-12, and tumor necrosis factor (TNF)-alpha. Therefore, the aim of this study was to investigate whether or not NF-kappaB activation regulates the formation of proinflammatory cytokines in human gestational tissues. Human placenta, amnion, and choriodecidua (n = 9 separate placentas) were incubated with 10 microg/ml of lipopolysaccharide (LPS) in the absence (control) or presence of SASP (0.1, 1, 5, or 10 mM). After 6 h of incubation, the tissues were collected, and NF-kappaB DNA binding activity in nuclear extracts was assessed by electromobility shift binding assay. The incubation medium was collected and the release of IL-6, IL-8, and TNF-alpha was quantified by ELISA. Treatment of placenta, amnion, and choriodecidua with SASP at concentrations 5 mM or greater significantly inhibited the release of IL-6, IL-8, and TNF-alpha, and NF-kappaB activation (ANOVA, P < 0.05). The data presented in this study demonstrate that the NF-kappaB transcription pathway is a key regulator of LPS-stimulated IL-6, IL-8, and TNF-alpha release from human gestational tissues. The control of NF-kappaB activation may therefore provide an alternative therapeutic strategy for reducing the release of proinflammatory mediators in infection associated preterm labor.