Distribution of TH17 cells in decidua from human early normal and anembryonic pregnancies
Date Issued
2009
Date
2009
Author(s)
Chen, Kai-Chieh
Abstract
Because half of the fetal genome derives from the father, the fetus is considered to be a foreigner by the maternal immune system. However concept is accepted without any rejection. This implies maintenance of normal pregnancy must be modified by several appropriate tolerogenic regulations in mammals. Leukocytes populations are an important component in human endometrium, and the populations increase at the first trimester of pregnancy compared with menstrual cycle. T cells in the human decidua are about 10% to 12% of total immune cells during pregnancy. CD4+ T helper cells are important players to modulate accurate immune responses. Recently a third subset of TH cells known as TH17 cells have been identified. Research in functions and regulatory roles of IL-17 and TH17 cells in human pregnancy is largely undetermined. As previous studies showed that many cytokines expressed in the maternal-fetal interface and exhibited regulatory roles in immunological tolerance, including IL-4, IL-1β, TNF-α, IFN-γ, TGF-β, IL-11, GM-CSF and IL-6. These cytokine milieu may support the differentiation of TH17 cells. IL-17 has been found in the maternal-fetal interface. Our previous results also showed CD8+ T cell-rich lymphoid aggregates are formed in decidua during early pregnancy. It suggests inflammation occurred in local environments and it’s known TH17 cells are one of the main mediator in inducing inflammation. Therefore, we propose that TH17 cells exist in human decidua after implantation. To investigate the TH17 population in decidua, we used immunostaining method to detect CD4+IL-17+ TH17 cells. Data indicated the phenotype of IL-17 producing cells are CD3+CD8- and CD3+CD4+ T cells. The percentage of CD4+IL-17+ TH17 cells in CD4+ T population are 41.5% in decidual tissues obtained from 11 cases of normal pregnancies and 19.5% in the decidua of anembryonic from 10 cases at 7-11 weeks of gestation. The TH17 cells are significantly higher in the decidua of normal pregnancies than that of anembryonic pregnancies. TGF-β is expressed exclusively on glandular epithelium, compared with IL-6 expression that is realatively scattered on stroma in decidua. TH17 cells appear as aggregates on stroma and the localization may be regulated by the existence of TGF-β and IL-6 in the decidua. The cytokine expression between normal and anembryonic pregnancy may be one of the reason causing the significant difference of TH17 population. TGF-β is comparably expressed between normal and anembryonic decidual tissues, however IL-6 positive staining seen to be more in the normal decidual tissues.The data showed TH17 cells proportion are higher in normal pregnancy and this could be the result of cytokine expresion diversity. Furthermore, this might indicate TH17 cells in decidua of human early pregnancy may have a unique role in mediating placenta development through the coordinated action of their effector cytokines.
Subjects
TH17 cell
IL-17
decidua
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