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-infl ammatory cytokines, such as interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, produced by the tissues are postulated to facilitate parturition. Infl uenza virus infection is one of causes of pregnancy-
associated complications, such as premature delivery, abortion and stillbirth. Recent studies have demonstrated that infl uenza virus infection induced the gene expression of a set of pro-infl ammatory
cytokines, such as IL-1β, IL-6, TNF-α, interferon (IFN)-β, IFN-g and granulocyte macrophage colony-stimulating factor (GM-CSF), and the secretion of unidentifi ed monocyte differentiationinducing 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-infl ammatory cytokine gene expression and apoptosis in fetal membrane chorion and amnion cells by infl uenza 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 infl uenza virus infection during pregnancy.

Keywords: Amnion - immunology, Amnion - virology, Chorion - immunology, Chorion - virology, Decidua - virology, Extraembryonic Membranes - immunology, Extraembryonic Membranes - virology, Influenza, Human - complications, Influenza, Human - immunology, Pregnancy Complications, Infectious - metabolism, Amnion - virology, Chorion - virology, Cytokines - genetics, Decidua - virology, Extraembryonic Membranes - virology, Influenza, Human - immunology, Pregnancy, Pregnancy Complications, Infectious - metabolism