Cytokines in Placental Physiology and Disease

The placenta forms connection between growing fetus and uterine wall and is a unique, temporary, highly specialized organ required for the development of the embryo and fetus. In humans, as early as 3-4 days after fertilization trophoblas-tic cells can be identified on the outer layer of cells within the blastocyst. These precursor cells differentiate into all the other placental cell types that build the future, highly specialized organ. After approximately 12-13 weeks (end of the first trimester of gestation) development of the maternal blood supply to the placenta is completed. The most important functions and roles of the human placenta include metabolic (synthesis of glycogen, cholesterol, and fatty acids), transport and exchange within maternal-placental-fetal interface (gases, nutrients, and waste products), endocrine (synthesis and secretion of the pregnancy supporting hormones), immunological (immuno-suppressive function that protects the fetal " allograft " from T-cell-mediated immune aggression as well as—to some degree—protective role against infectious agents). Many research papers elucidated that physiological phenomena related to normal growth, development, and reproduction of living organisms are govern by complex cytokine interactions. It is becoming increasingly apparent that cytokines (CKs) not exclusively are synthesized within the " immune cells, " but are the product of a whole host of cell types, including nonimmune and/or structural cells such as epithelial cells, cytotrophoblast cells, and fibroblasts. Almost all CKs are pleiotropic effectors showing multiple biological activities. Interestingly, the human placenta produces a variety of CKs and expresses virtually all known CKs. Both successful placentation with trophoblast invasion and normal placental development accompanied by vascular and angiogenesis require precise balance between all members of the local (utero-placento fetal) cytokine network. Increased number of the innovative research approaches devoted to the better understanding of the connections between CKs, their receptors, and placental malfunction have recently been undertaken. On this background, the data about the role of cytokines in placental physiology and disease are still accumulating. The studies are focusing on the involvement of CKs in the processes of implantation, invasion of the trophoblast into the spiral uterine arteries, placental angiogenesis, response to inflammatory and immunologic factors in the uteroplacental interface, and induction of term/preterm labour. In this special issue of Mediators of Inflammation, I am pleased to present to the reader several articles written by experts in the field. All of them share the same subject mater, CKs in the human uteroplacental compartment. Modifications in the production of CKs by human …