Maternal Immune Stimulation With Interferon-Gamma Limits Embryonic Valproic Acid Induced Apoptotic Gene Expression

Neural tube defects (NTDs) are developmental malformations affecting 1300 newborns in the United States each year. Valproic acid (VA), a drug to treat seizures and mood disorders, can cause NTDs. Apoptosis is increased in the developing neural tubes (NTs) of embryos exposed to VA thereby identifying a possible mechanism for NTD formation. Numerous studies show that maternal immune stimulation (MIS) in the periconceptual period reduces birth defects including VA-induced NTDs. It is hypothesized that immunoregulatory cytokines may normalize the dysregulated apoptosis. This study examined maternal cytokine production and embryonic apoptotic gene expression following prebreeding stimulation with interferon-γ (IFN-γ) and gestational VA exposure.

Concentrations of granulocyte monocyte colony stimulating factor (GM-CSF), IFN-γ, interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-α (TNFα) were determined in VA + IFN-γ-treated pregnant mice. Expression of pro-apoptotic and antiapoptotic pathway genes was determined in VA and VA + IFN-γ exposed embryos.

NTDs decreased from 45.3% to 21.2% per litter with MIS. MIS altered the profiles of GM-CSF and IFN-γ throughout pregnancy and altered the profiles of GM-CSF, IL-6, and IL-10 over the time of NT closure. Pro-apoptotic genes were upregulated, and anti-apoptotic genes were downregulated in VA-exposed embryonic heads with open or closed NTs. Gene expression was normalized with VA + IFN-γ in embryonic heads with closed NTs.

This study identified GM-CSF and IFN-γ as possible effectors of MIS and specifically GM-CSF, IL-6, and IL-10 in preventing NTDs. MIS normalized apoptotic gene expression in embryos with closed NTs identifying a possible molecular mechanism for the prevention of VA-induced NTDs.