title: NF-kappaB-regulated suppression of T-bet in T cells represses Th1 immune responses in pregnancy.
abstract: The molecular mechanisms that suppress Th1 immune responses in pregnancy are unknown. We assessed the expression of the Th1 cytokine transcription factor T-bet. We isolated PBMC and T cells from non-pregnant and pregnant women and demonstrated that T-bet is specifically down-regulated in pregnancy under basal and stimulated conditions. Low levels of T-bet protein were detected in the nuclear fraction of unstimulated PBMC from non-pregnant, but not pregnant women. Nuclear levels of T-bet increased in response to PMA/ionomycin in PBMC from non-pregnant, but not pregnant women. T-bet expression was greater in whole cell lysates of stimulated CD3(+) T cells from non-pregnant relative to pregnant women. NF-kappaB is specifically down-regulated in T cells in pregnant women, resulting in suppressed expression of Th1 cytokines IL-2, IFN-gamma and TNF-alpha. In this study, down-regulation of NF-kappaB also resulted in diminished expression of T-bet. PMA induces NF-kappaB translocation, T-bet expression and IL-2, IFN-gamma and TNF-alpha production. Conversely, pre-incubation with SN50, and NF-kappaB oligodeoxyribonucleotide decoys suppressed PMA-induced NF-kappaB translocation and gene transcription, respectively, resulting in diminished T-bet expression and Th1 cytokine production. Therefore, maintenance of the cytokine environment for pregnancy success is mediated via strict regulation of Th1 immune responses, more specifically through control of NF-kappaB and T-bet transcription.
authors.affiliation: Perinatal Research Group, Kolling Institute of Medical Research, University of Sydney, St Leonards, Australia. smccrack@med.usyd.edu.au
authors.forename: Sharon A
authors.initials: SA
authors.lastname: McCracken
authors.forename: Katrina
authors.initials: K
authors.lastname: Hadfield
authors.forename: Zolaikha
authors.initials: Z
authors.lastname: Rahimi
authors.forename: Eileen D
authors.initials: ED
authors.lastname: Gallery
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Morris
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D011247:Pregnancy / Q000276:immunology*; D020825:T-Box Domain Proteins / Q000276:immunology* / Q000378:metabolism; D018417:Th1 Cells / Q000276:immunology* / Q000378:metabolism; D000098815:T-bet Transcription Factor
chemical_list: D016207:Cytokines; D016328:NF-kappa B; D020825:T-Box Domain Proteins; D000098815:T-bet Transcription Factor