Excess palmitate induces decidual stromal cell apoptosis via the TLR4/JNK/NF-kB pathways and possibly through glutamine oxidation

During gestation, excess palmitate (PA) is enriched in decidua. Both excess PA and decidual dysfunctions are associated with numerous adverse pregnancy outcomes such as gestational diabetes, preeclampsia and preterm birth and intrauterine growth restriction. Here, mRNA data about the effects of PA were collected from multiple databases and analyzed. Human decidual tissues were obtained from clinically normal pregnancies, terminated for non-medical reasons, during the first trimester, and decidual stromal cells (DSCs) were isolated and exposed to PA, alone or together with the inhibitors of Toll-like receptor 4 (TLR4), Jun N-terminal kinase (JNK), nuclear factor-kappa-gene binding (NF-kB) or glutamine (GLN) oxidation. Furthermore, DSCs were transfected with lentiviral particles overexpressing human TLR4. We demonstrate that excess PA interacting with its receptor TLR4 disturbs DSC hemostasis during the first trimester. Specifically, high PA signal induced DSC apoptosis and formed an inflammatory program (elevated interleukin-1 beta and decreased interleukin-10) via the activation of TLR4/JNK/NF-kB pathways. A complexed cross-talk was found between TLR4/JNK/NF-kB signals and PA deposition in DSCs. Besides, under an excess PA environment, GLN oxidation was significantly enhanced in DSCs and the suppression of GLN oxidation further augmented PA-mediated DSC apoptosis and inflammatory responses. In conclusion, excess PA induces apoptosis and inflammation in DSCs via the TLR4/JNK/NF-kB pathways, which can be augmented by the suppression of GLN oxidation.