krn-7000 and Premature-Birth

Preterm birth (PTB) is the leading cause of neonatal morbidity and mortality worldwide. Although intra-amniotic infection is a recognized cause of spontaneous preterm labor, the noninfection-related etiologies are poorly understood. In this article, we demonstrated that the expansion of activated CD1d-restricted invariant NKT (iNKT) cells in the third trimester by administration of α-galactosylceramide (α-GalCer) induced late PTB and neonatal mortality. In vivo imaging revealed that fetuses from mice that underwent α-GalCer-induced late PTB had bradycardia and died shortly after delivery. Yet, administration of α-GalCer in the second trimester did not cause pregnancy loss. Peroxisome proliferator-activated receptor (PPAR)γ activation, through rosiglitazone treatment, reduced the rate of α-GalCer-induced late PTB and improved neonatal survival. Administration of α-GalCer in the third trimester suppressed PPARγ activation, as shown by the downregulation of Fabp4 and Fatp4 in myometrial and decidual tissues, respectively; this suppression was rescued by rosiglitazone treatment. Administration of α-GalCer in the third trimester induced an increase in the activation of conventional CD4(+) T cells in myometrial tissues and the infiltration of activated macrophages, neutrophils, and mature dendritic cells to myometrial and/or decidual tissues. All of these effects were blunted after rosiglitazone treatment. Administration of α-GalCer also upregulated the expression of inflammatory genes at the maternal-fetal interface and systemically, and rosiglitazone treatment partially attenuated these responses. Finally, an increased infiltration of activated iNKT-like cells in human decidual tissues is associated with noninfection-related preterm labor/birth. Collectively, these results demonstrate that iNKT cell activation in vivo leads to late PTB by initiating innate and adaptive immune responses and suggest that the PPARγ pathway has potential as a target for prevention of this syndrome.

Topics: Animals; Cytokines; Disease Models, Animal; Female; Fluorescent Antibody Technique; Galactosylceramides; Humans; Hypoglycemic Agents; Immunophenotyping; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Natural Killer T-Cells; PPAR gamma; Pregnancy; Premature Birth; Real-Time Polymerase Chain Reaction; Rosiglitazone; Thiazolidinediones

Stimulation of CD1d-restricted semiinvariant natural killer T cells by using the CD1d ligand alpha-galactosylceramide (alphaGalCer) induces pregnancy loss in mice through an ill-defined mechanism involving TNF, IFN-gamma, and perforin. In this article, we demonstrate that during early gestation, alphaGalCer efficiently induced pregnancy loss in C57BL/6J and BALB/cJ mice in a perforin-dependent manner. In contrast, during midgestation perforin was no longer required for pregnancy loss. Concomitant with the loss of a perforin requirement at midgestation was the emergence of strain-dependent variations in susceptibility to alphaGalCer-induced pregnancy loss. Whereas pregnant C57BL/6J mice remained susceptible to alphaGalCer at midgestation, pregnant BALB/cJ mice were resistant to its effects. Pregnancy loss during midgestation was correlated with dramatically higher serum cytokine levels, including TNF and IL-2, in the susceptible C57BL/6J strain compared with the resistant BALB/cJ strain. Thus, the stage of gestation defined two distinct mechanisms of pregnancy loss: a perforin-dependent mechanism operating at early gestation and a perforin-independent, cytokine-dominated mechanism operating after midgestation.

Topics: Animals; Antigens, CD1; Antigens, CD1d; Female; Galactosylceramides; Interleukin-2; Killer Cells, Natural; Ligands; Membrane Glycoproteins; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Perforin; Pore Forming Cytotoxic Proteins; Pregnancy; Premature Birth; T-Lymphocytes; Tumor Necrosis Factor-alpha