Regulation of Phospholipase Isozymes by Nuclear Factor-κB in Human Gestational Tissuesin Vitro

Abstract

Phospholipid-derived mediators are implicated in the initiation and progression of human labor and delivery, particularly in relation to infection-induced preterm labor. We previously demonstrated that, in human intrauterine tissues, lipopolysaccharide (LPS)-stimulated nuclear factor-kappaB (NF-kappaB) DNA binding activity, and subsequent cytokine release can be suppressed by sulfasalazine (SASP) concentrations greater than 5 mM. The aim of this study was to elucidate the effect the SASP on secretory type II phospholipase A(2) (PLA(2)), cytosolic PLA(2) (cPLA(2)), cyclooxygenase (COX) isozymes, and subsequent prostaglandin F(2alpha) (PGF(2alpha)) production in human gestational tissues. Human placenta, amnion, and choriodecidua (n = 4-9 separate placentas) were incubated in the presence of SASP (0.1, 1, 5, and/or 10 mM) under either basal or LPS (10 microg/ml) conditions. After 6 h incubation, the tissues were collected and assayed for type II PLA(2) by ELISA and cPLA(2), COX-1, and COX-2 content by Western blotting. The incubation medium was collected and assayed for type II PLA(2) and 13,14-dihydro-15-keto PGF(2alpha) release by ELISA and PGF(2alpha) by RIA. Treatment of placenta, amnion, and choriodecidua with SASP concentrations greater than 5 mM significantly inhibited basal and/or LPS-stimulated type II PLA(2) content and release, 13,14-dihydro-15-keto PGF(2alpha) release, and cPLA(2) protein content (ANOVA, P < 0.05); however, no effect of SASP was observed on basal or LPS-stimulated COX-1 or COX-2 protein. Although no effect of SASP was observed on basal and LPS-stimulated PGF(2alpha) release from placenta and amnion, it significantly increased both basal and LPS-stimulated PGF(2alpha) release from choriodecidua. In addition, SASP concentrations of 5 mM or greater significantly suppressed NF-kappaB DNA binding activity. These data are consistent with the hypothesis that NF-kappaB regulates the expression and release of phospholipase isozymes.

Activation and induction of cytosolic phospholipase A2 by TNF‐α mediated through Nox2, MAPKs, NF‐κB, and p300 in human tracheal smooth muscle cells

“…In the present study, we found that pretreatment with helenalin or transfection with kinase inactive mutants of NIK and IKKb also attenuated TNF-a-induced NF-kB translocation and cPLA 2 expression, as well as PGE 2 production. These results suggested that TNF-a-stimulated NF-kB activation was mediated through NIK/IKKb pathway leading to cPLA 2 expression, consistent with the reports indicating that activation of NF-kB promotes cPLA 2 gene expression in several cell types (Lappas et al, 2004;Luo et al, 2006). Moreover, our results showed that pretreatment with helenalin, U0126, SB202190, or SP600125 significantly attenuated cPLA 2 luciferase gene activity stimulated by TNF-a, suggesting that activation of MAPKs and NF-kB pathways independently regulated cPLA 2 expression at a transcription level.…”

Antinephrolithiatic and antioxidative efficacy ofDolichos biflorusseeds in a lithiasic rat model

“…Reactive oxygen species also culminate in phospholipase A 2 activation through transcription factor NF-kB (Lappas et al, 2004), as NF-kB can be activated by the stress of oxidants (Siebenlist et al, 1994) and oxalate exposure promotes rapid degradation of IkBa, an endogenous inhibitor of the NF-kB transcription factor (Jonassen et al, 2005). The inhibition of the lipid peroxidation (decreased MDA level) after post-treatment of plant extracts can be attributed to scavenging the ROS and indirect inhibition of phospholipase A 2 through inactivation of NF-kB.…”

Aqueous extract ofBoerhaavia diffusaroot ameliorates ethylene glycol-induced hyperoxaluric oxidative stress and renal injury in rat kidney

“…ROS also culminate in phospholipase A 2 activation through transcription factor NF-κB (Lappas et al, 2004), as NF-κB can be activated by the stress of oxidants (Siebenlist et al, 1994) and oxalate exposure promotes rapid degradation of IκBα, an endogenous inhibitor of the NF-κB transcription factor (Jonassen et al, 2005). The inhibition of the lipid peroxidation (decreased MDA level) after post-treatment of BDE can be attributed to scavenging the ROS and indirect inhibition of phospholipase A 2 through inactivation of NF-κB.…”