Induction of pro-inflammatory cytokine gene expression and apoptosis in human chorion cells of fetal membranes by influenza virus infection: possible implications for maintenance and interruption of pregnancy during infection.

Human fetal membranes are composed of amnion, chorion and decidua tissues, which play a critical role in defense barriers as well as maintenance of pregnancy and parturition. Pro-inflammatory cytokines, such as interleukin (IL)-1beta, IL-6 and tumor necrosis factor (TNF)-alpha, produced by the tissues are postulated to facilitate parturition. Influenza virus infection is one of causes of pregnancy-associated complications, such as premature delivery, abortion and stillbirth. Recent studies have demonstrated that influenza virus infection induced the gene expression of a set of pro-inflammatory cytokines, such as IL-1beta, IL-6, TNF-alpha, interferon (IFN)-beta, IFN-gamma and granulocyte macrophage colony-stimulating factor (GM-CSF), and the secretion of unidentified monocyte differentiation-inducing factor(s) from primary cultured chorion cells undergoing apoptosis. These phenomena were not observed in primary cultured amnion cells infected with the virus. This article reviews, (1) the production of cytokines in fetal membrane tissues and their functions; (2) the differential induction of pro-inflammatory cytokine gene expression and apoptosis in fetal membrane chorion and amnion cells by influenza virus infection. An accumulating number of evidence suggests that interactive reactions between fetal membrane chorion cells and maternal monocytes/macrophages may play a critical role in defense barriers against the virus infection. Understanding the interactions would make important contributions to the elucidation of the pathogenesis of influenza virus infection during pregnancy.