Role of HLA-G, HLA-E and KIR2DL4 in Pregnancy

Gestational Viral Infections: Role of Host Immune System

Viral infections in pregnancy are major causes of maternal and fetal morbidity and mortality. Infections can develop in the neonate transplacentally, perinatally, or postnatally (from breast milk or other sources) and lead to different clinical manifestations, depending on the viral agent and the gestational age at exposure. Viewing the peculiar tolerogenic status which characterizes pregnancy, viruses could exploit this peculiar immunological status to spread or affect the maternal immune system, adopting several evasion strategies. In fact, both DNA and RNA virus might have a deep impact on both innate and acquired immune systems. For this reason, investigating the interaction with these pathogens and the host's immune system during pregnancy is crucial not only for the development of most effective therapies and diagnosis but mostly for prevention. In this review, we will analyze some of the most important DNA and RNA viruses related to gestational infections.

EXPRESSION OF HUMAN LEUKOCYTE ANTIGEN-E AND NATURAL KILLER CELLS IN INTRA UTERINE FETAL DEATH

Intra Uterine Fetal Death (IUFD) is one contributor to infant mortality. Human Leukocyte Antigen-E (HLA-E) and Natural Killer Cells (NK cells) are believed to play an important role towards IUFD associated with immune maladaptation. This study aimed to determine the expression of HLA-E and NK cells on trophoblast on IUFD and normal pregnancy. The study used cross sectional approach undertaken at Department of Obstetrics and Gynecology, Dr. Moewardi Hospital, Surakarta, networking hospitals, and Anatomic Pathology Laboratory of Faculty of Medicine, Sebelas Maret University. The number of samples were 32 subjects consisting of 16 subjects with normal pregnancy and 16 subjects with IUFD. The expression of HLA-E and NK cells on trophoblast of subjects who met the inclusion and exclusion criteria were examined using immunohistochemistry method and t-test statistical analysis. The mean value of HLA-E expression in the trophoblast of IUFD group was 17.30±6.69, in normal pregnancy was 57.06±32.04, with p=0.00 (p<0.05). The mean value of NK cell expression in trophoblast in IUFD group was 78.62±36.43, in normal pregnancy was 19.87±6.43, with p=0.00 (p<0.05). This study concluded that the expression of HLA-E was lower and NK cells wass higher in IUFD compared to those in normal pregnancy.

Quantified colocalization reveals heterotypic histocompatibility class I antigen associations on trophoblast cell membranes: relevance for human pregnancy

Human placental syncytiotrophoblasts lack expression of most types of human leukocyte antigen (HLA) class I and class II molecules; this is thought to contribute to a successful pregnancy. However, the HLA class Ib antigens HLA-G, -E, and -F and the HLA class Ia antigen HLA-C are selectively expressed on extravillous trophoblast cells, and they are thought to play a major role in controlling feto-maternal tolerance. We have hypothesized that selective expression, coupled with the preferential physical association of pairs of HLA molecules, contribute to the function of HLA at the feto-maternal interface and the maternal recognition of the fetus. We have developed a unique analytical model that allows detection and quantification of the heterotypic physical associations of HLA class I molecules expressed on the membrane of human trophoblast choriocarcinoma cells, ACH-3P and JEG-3. Automated image analysis was used to estimate the degree of overlap of HLA molecules labeled with different fluorochromes. This approach yields an accurate measurement of the degree of colocalization. In both JEG-3 and ACH-3P cells, HLA-C, -E, and -G were detected on the cell membrane, while the expression of HLA-F was restricted to the cytoplasm. Progesterone treatment alone induced a significant increase in the expression level of the HLA-G/HLA-E association, suggesting that this heterotypic association is modulated by this hormone. Our data shows that the cell-surface HLA class I molecules HLA-G, -E, and -C colocalize with each other and have the potential to form preferential heterotypic associations.