HIV-associated immune dysregulation in the placenta

Abstract

Introduction: HIV infection is highly associated with adverse pregnancy outcomes. Some of which include still births, perinatal mortality, intrauterine growth restriction, low birth weight, spontaneous miscarriages and still births. These numbers are even more pronounced in untreated HIV infection. Understanding the impact of HIV and immune phenotypes present in decidual and villi and their cellular gene expression will increase our understanding of HIV associated pathology in African women living with HIV. These findings can be utilised for modifying treatment regimens, interventions, and diagnostics to identify pregnant women living with HIV who are at risk of adverse, pre-term or low birth weight birth. Methods: Woman with clinically diagnosed HIV-1 infection regardless of ART status recruited from the parent study “Trained immunity in BCG vaccinated African infants (TIA)” at QECH are recruited in the study. Following patient's consent, 5ml of peripheral blood is collected in heparin tubes from the mother. Immediately after delivery at least 30 ml of cord blood in drawn from the umbilical cord vein. Whole blood is used for enzymatic bead assay to determine granulocyte and monocyte function.The placenta is then carefully examined for any inflammation or irregularities followed by the careful cutting of biopsies, umbilical cord, villi decidual basalis and the membranes; chorion and ammonitic membrane (CAM).2.3g of placental biopsy tissue is weighed and digested using the miltenyi umbilical cord kit. Upon isolation of the lymphocytes from cord/peripheral blood and placenta. 1,000,000 cells/ml are stored in freezing media. All cells are frozen for further analysis for immunophenotyping, optimisations and single cell RNA sequencing. Results: Following optimisations the Miltenyi umbilical cord digestion kit had the highest recovery and viability of leukocytes when compared to the percol method and multi tissue kit.Neutrophils isolated from HIV-exposed cord blood had similar enzymatic function when challenged with zymosan coated beads in a whole blood reporter assay. Monocytes displayed a trend of lower proteolysis.T-cell phenotyping of placental decidua cells revealed abundant T-cell populations of naive and effector T-cells, with augmented memory populations in placental immune populations from HIV+ compared to HIV- mothers. Discussion: HIV-infection is associated with immune cell alterations when comparing decidual immune cells from HIV+ mothers with HIV-. Conclusion: HIV may play a role in adverse birth outcomes through immune cell dysregulation and alteration in placental homeostasis.