A dual-receptor mechanism between integrins and ACE2 widens SARS-CoV-2 tissue tropism (preprint)

In addition to the ACE2 receptor, SARS-CoV-2 binds to integrins to gain host cell entry and trigger pro-inflammatory integrin-mediated signalling cascades. Integrins, therefore, are likely candidates for a dual-receptor mechanism with ACE2 to explain the increased infectivity seen in SARS-CoV-2 models. As integrins are primarily expressed in vasculature and persistent vasculopathy is seen in COVID-19, examining the role of endothelial integrin involvement is crucial in uncovering the pathophysiology of SARS-CoV-2.

Endothelial Cells and SARS-CoV-2: An Intimate Relationship (preprint)

Angiotensin-converting enzyme 2 (ACE2) is an important player of the renin-angiotensin-aldosterone system (RAAS) in regulating the conversion of angiotensin II into angiotensin (1-7). While expressed on the surface of human cells, such as lung, heart, kidney, neurons, and endothelial cells (EC), ACE2 is the entry receptor for SARS-CoV-2. Here, we would like to highlight that ACE2 is predominant on the EC membrane. Many of coronavirus disease 2019 (COVID-19) symptoms have been associated with the large recruitment of immune cells, directly affecting EC. Additionally, cytokines, hypoxia, and complement activation can trigger the activation of EC leading to the coagulation cascade. The EC dysfunction plus the inflammation due to SARS-CoV-2 infection may lead to abnormal coagulation, actively participating in thrombo-inflammatory processes resulting in vasculopathy and indicating poor prognosis in patients with COVID-19. Considering the intrinsic relationship between EC and the pathophysiology of SARS-CoV-2, EC-associated therapies such as anticoagulants, fibrinolytic drugs, immunomodulators, and molecular therapies have been proposed. In this review, we will discuss the role of EC in the lung inflammation and edema, in the disseminate coagulation process, ACE2 positive cancer patients, and current and future EC-associated therapies to treat COVID-19.

Placental SARS-CoV-2 in a patient with mild COVID-19 disease (preprint)

Background: The full impact of COVID-19 on pregnancy remains uncharacterized. Current literature suggests minimal maternal, fetal, and neonatal morbidity and mortality,1 and COVID-19 manifestations appear similar between pregnant and non-pregnant women.2 We present a case of placental SARS-CoV-2 virus in a woman with an uncomplicated pregnancy and mild COVID-19 disease. Methods: A pregnant woman was evaluated at University of Missouri Women and Childrens Hospital. Institutional review board approval was obtained; information was obtained from medical records. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to detect SARS-CoV-2. A gynecological pathologist examined the placenta and performed histolopathology. Sections were formalin-fixed and paraffin-embedded; slides were cut and subjected to hematoxylin-and-eosin or immunohistochemistry (IHC) staining. IHC was performed with specific monoclonal antibodies to detect SARS-CoV-2 antigen or to identify trophoblasts. Findings: A 29 year-old multigravida presented at 40-4/7 weeks for labor induction. With myalgias two days prior, she tested positive for SARS-CoV-2. Her parents were in self-isolation for COVID-19 positivity; husband was asymptomatic and tested negative for COVID-19, but exposed to a workplace (meatpacking facility) outbreak. Prenatal course was uncomplicated, with no gestational hypertension. She was afebrile and asymptomatic with normal vital signs throughout hospitalization. Her myalgias improved prior to admission. A liveborn male infant was delivered vaginally. Newborn course was uneventful; he was appropriate for gestational age, physical was unremarkable, and he was discharged home at 36 hours. COVID-19 RT-PCR test was negative at 24 hours. At one-week follow-up, newborn was breastfeeding well, with no fevers or respiratory distress. Overall placental histology is consistent with acute uterine hypoxia (subchorionic laminar necrosis) superimposed on chronic uterine hypoxia (extra-villous trophoblasts and focal chronic villitis). IHC using SARS-CoV-2 nucleocapsid-specific monoclonal antibody demonstrated SARS-CoV-2 antigens throughout the placenta in chorionic villi endothelial cells, and rarely in CK7-expressing trophoblasts. Negative control placenta (November 2019 delivery) and ferret nasal turbinate tissues (not shown) were negative for SARS-CoV-2. Interpretation: In this report, SARS-CoV-2 was found in the placenta, but newborn was COVID-19 negative. Our case shows maternal vascular malperfusion, with no features of fetal vascular malperfusion. To our knowledge, this is the first report of placental COVID-19 despite mild COVID-19 disease in pregnancy (with no symptoms of COVID-19 aside from myalgias); specifically, this patient had no fever, cough, or shortness of breath, but only myalgias and sick contacts. Despite her having mild COVID-19 disease in pregnancy, we demonstrate placental vasculopathy and presence of SARS-CoV-2 virus across the placenta. Evidence of placental COVID-19 raises concern for possible placental vasculopathy (potentially leading to fetal growth restriction, pre-eclampsia, and other pregnancy complications) as well as for potential vertical transmission -- especially for pregnant women who may be exposed to COVID-19 in early pregnancy. Further studies are urgently needed, to determine whether women with mild, pre-symptomatic, or asymptomatic COVID-19 may have SARS-CoV-2 virus that can cross the placenta, cause fetal vascular malperfusion, and possibly affect the fetus. This raises important public health and public policy questions of whether future pregnancy guidance should include stricter pandemic precautions, such as screening for a wider array of COVID-19 symptoms, increased antenatal surveillance, and possibly routine COVID-19 testing on a regular basis throughout pregnancy.

First case of placental infection with SARS-CoV-2 (preprint)

Background: The effects of Covid-19 in pregnancy remain relatively unknown. We present a case of second trimester pregnancy with symptomatic Covid-19 complicated by severe preeclampsia and placental abruption. Methods: We analyzed placenta for the presence of SARS-CoV-2 through molecular and immunohistochemical assays and by and electron microscopy, and we measured the maternal antibody response in blood to this infection. Results: SARS-CoV-2 localized predominantly to syncytiotrophoblast cells at the maternal-fetal interface of the placenta. Histological examination of the placenta revealed a dense macrophage infiltrate, but no evidence for vasculopathy typically associated with preeclampsia. Conclusion: This case demonstrates, for the first time, SARS-CoV-2 invasion of the placenta, highlighting the potential for severe morbidity among pregnant women with Covid-19.