LAUSR

OBJECTIVES To immuno-localize histone H2A expression as a marker of neutrophil extracellular traps (NETs) in the placenta; and to quantify and compare the percentage H2A immune-expression as a marker of NETs in the placental intervillous space according to: pregnancy type, HIV status and across the study population. STUDY DESIGN The participants to the study were a pregnant South African population group of African ancestry (n = 60) stratified as normotensive (N) (n = 30) or pre-eclamptic (PE) (n = 30) and further subdivided as HIV infected (HIV+) (n = 15) or HIV naïve (HIV-) (n = 15). Following informed consent placental tissue samples were obtained at the time of delivery. Immunohistochemistry using the anti-histone 2A (H2A) antibody as a biomarker of NETs, and morphometric image analysis was used to immuno-localize and quantify placental H2A immuno-expression respectively in the placental inter-villous space. Statistical analysis was performed using Graph Pad Prism software (Version 5). MAIN OUTCOME MEASURES To determine if HIV neutralizes the elevated NETs in PE. RESULTS NETs were localized within the inter-villous space surrounding the exchange villi and conducting villi of placental tissue. Based on HIV status, a significant elevation in H2A immuno-expression was observed in the HIV+ compared to the HIV- group (p = 0.0008) and in the pre-eclampsia HIV- compared to the normotensive HIV- group (p = 0.0008). However, a significant decline in H2A immuno-expression was observed in the PEHIV+ group compared to the NHIV+ group (p = 0.0072). CONCLUSIONS Both PE and HIV elevate placental NETs; however, they synergistically downregulate NETs expression. Further investigations are required to interrogate the signaling pathways involved to establish potential NET-targeted therapeutic actions.