915 Sex differences in placental expression of ACE2 and TMPRSS2 in maternal SARS-CoV-2 infection

Shook, Lydia; Bordt, Evan; Yockey, Laura; James, Kaitlyn E.; Roberts, Drucilla J.; Edlow, Andrea G.

Objective: Sex differences in the immune response to SARS-CoV-2 infection have been described. ACE2 and TMPRSS2, host cell receptors required for viral entry, are regulated by sex steroids and expressed by trophoblasts. Although vertical transmission of SARS-CoV-2 is rare, how the placenta defends against SARS-CoV-2, and whether there is a sex bias in the risk of vertical transmission, is not well understood. We sought to investigate whether placental ACE2 and TMPRSS2 expression vary by fetal sex in the presence of maternal SARS-CoV-2 infection. Study Design: This is a cohort study of 66 pregnant women (37 SARS-CoV-2 exposed, 29 SARS-CoV-2 unexposed) enrolled on admission to Massachusetts General Hospital from April-June 2020, coincident with universal screening for SARS-CoV-2 infection. SARS-CoV-2 exposure status was determined by nasopharyngeal RT-PCR. Groups were balanced for fetal sex and maternal disease severity. RNA was isolated from placental homogenates and RTqPCR was performed to quantify expression of ACE2 and TMPRSS2 relative to the reference gene YWHAZ, using the 2-(DELTADELTACt) method. The impact of fetal sex and SARS-CoV-2 exposure on ACE2 and TMPRSS2 expression was analyzed by 2-way ANOVA. Previously determined placental viral loads showed no evidence of SARS-CoV-2 infection in any placentas. Result(s): While there were no fetal sex or SARS-CoV-2 exposure-mediated differences in ACE2 expression (1A), we observed 1.73-fold increased TMPRSS2 expression in SARS-CoV-2 exposed placentas of female offspring compared to female controls (P=0.04, 1B), and 1.84 -fold reduced TMPRSS2 expression in SARS-CoV-2 exposed placentas of male offspring compared to male controls (P=0.0003, 1B). TMPRSS2 expression was significantly higher in placentas of male compared to female offspring in controls (P<0.0001). Conclusion(s): Sexually dimorphic patterns of TMPRSS2 placental gene expression were observed in the setting of maternal SARS-CoV-2 infection, driven by sex differences in TMPRSS2 expression in controls. Implications of these findings for offspring vulnerability to vertical transmission warrants further investigation. [Formula presented]Copyright © 2020