Expression of Human Leukocyte Antigen-G in Placental Tissues from Pregnant Women with Preeclampsia

Objective: To study the gene and protein expressions of human leukocyte antigen-G (HLA-G) in the placental tissues from healthy women in late pregnancy and pregnant women with preeclampsia (PE), and to explore the relationship between HLA-G and PE. Methods: Immunohistochemistry, Western blot and RT-PCR were used to detect the expressions of HLA-G protein and mRNA in the maternal placenta of 60 pregnant women with PE (including 30 cases of mild PE and 30 cases of severe PE) and 30 healthy full-term pregnant women (control group) respectively. Results: HLA-G had its expression mainly on the surface of trophoblast cells, and its response range and reactivity of its immunologic tissue were further reduced and weakened as the patient's condition was aggravated. The protein expression of placental HLA-G in each PE group was significantly lower than control group, with the difference statistically significant (all P<0.05). Compared with mild PE group, the protein expression level of HLA-G was lower in severe PE group (P<0.05). The Spearman's correlation analysis for HLA-G and PE severity showed that the correlation coefficient was -0.892 (rs = -0.892) (P<0.05), indicating that the expression of HLA-G protein was significantly negatively correlated to the severity of PE. The mRNA expression level of placental HLA-G of each PE group was significantly lower than that of control group, and the difference was statistically significant (all P<0.05). But the mRNA expression level of HLA-G was significantly lower in severe PE group than in mild PE group (P<0.05). Conclusion: The decreased expression of HLA-G in placenta may be involved in the pathogenesis of PE, and can also reflect the severity of this disease.