Serum Levels of Collectins Are Sustained During Pregnancy: Surfactant Protein D Levels Are Dysregulated Prior to Missed Abortion.

About 15% of pregnant women undergo missed abortion (MA), wherein women do not experience cramping and vaginal bleeding. Dysregulation of the immune molecules and steroid hormones contribute to early pregnancy loss. Collectins- surfactant protein A (SP-A), surfactant protein D (SP-D), and mannose-binding lectin (MBL) are a group of innate immune molecules regulated by the steroid hormones. Reduced levels of SP-A and SP-D during the early gestation exhibited a significant association with the severe early onset preeclampsia. In order to determine the serum profile of collectins throughout the normal pregnancy and explore their predictive potential during the 8-12 weeks of gestation for MA, we examined a prospective cohort of pregnant women (n = 221). The serum levels of SP-A and SP-D were significantly downregulated in the normal pregnant women in all the three trimesters (n = 30) compared with the non-pregnant women (n = 20) and were not significantly different across the three trimesters. Fourteen of the women from the cohort underwent MA during the 14-20 weeks of gestation and exhibited a significant downregulation in the serum levels of SP-D during 8-12 weeks of gestation. A significant inhibition of the HTR-8/SVneo cell proliferation and migration in the presence of a recombinant fragment of human SP-D suggested the relevance of SP-D in placental development. We report here that the serum levels of SP-A, SP-D, and MBL are consistently maintained during pregnancy in the Indian cohort. Dysregulated serum levels of SP-D and P4/E2 ratio during the early first trimester may predict occurrence of MA.