Long-term neurodevelopmental sequelae are a potential concern in neonates following in utero exposure to severe acute respiratory syndrome coronavirus disease 2 (SARS-CoV-2). This report by American scientists summarizes the severe neurodevelopmental sequelae in two neonates following in utero exposure to SARS-CoV-2, with the spike (S) protein in the brain of the deceased infant and both placentas.
About the cases
This study describes cases of two infants born in the third trimester to mothers with COVID-19 infection during pregnancy. Mothers tested SARS-CoV-2 positive by nasopharyngeal swab reverse transcription polymerase chain reaction (NP RT-PCR) several weeks before delivery. At birth, neither infant was SARS-CoV-2 positive (NP RT-PCR), but both had SARS-CoV-2 IgG, combined (total) IgG, IgM, and IgA reactivity to a recombinant derivative of SARS-CoV-2 spike protein. In addition, serum inflammatory markers and cytokines were markedly elevated.
Patient 1: Preterm infant
A 32-week gestational age, appropriately grown, male infant was born with Apgar scores of 4 and 7 . The mother was healthy until 27 weeks of gestation when she was admitted to the ICU for pneumonia and multisystem disease, diagnosed as SARS-CoV-2 by NP RT-PCR.
After birth, newborn immediately displayed seizure-like activity and poor respiratory effort requiring intubation and assisted ventilation. Bilateral confluent densities originally presented on the initial chest radiograph did not completely resolve after full respiratory recovery. Conventional electroencephalography (EEG) showed frequent multifocal epileptiform discharges consistent with status epilepticus.
At 24 hours of age, the newborn’s NP RT-PCR for SARS-CoV-2 was negative. However, the he had SARS-CoV-2 IgG, combined (total) IgG, IgM, and IgA reactivity to a recombinant derivative of SARS-CoV-2 spike protein, and serum inflammatory markers and cytokines were markedly elevated. The infant was discharged after 3 months with a seizure disorder and microcephaly. His 12-month neurologic examination remained abnormal, with head lag, truncal hypotonia, hyperreflexia, and delayed developmental milestones.
At 13 months of age, the infant died suddenly. Autopsy showed a significant reduction in brain weight and cerebral white matter volume, enlarged ventricles, extensive gliosis and evidence of virus throughout the brain. Immunofluorescence identified the S1 protein, colocalized with nucleocapsid protein, throughout the brain of deceased infant.
Patient 2: Full-term infant
A 39-week gestational age, appropriately grown, female infant was born with Apgar scores of 4 and 6. The mother reported an asymptomatic SARS-CoV-2 positivity (NP RT-PCR) in the late second trimester, followed by a negative test. Although asymptomatic, she again tested positive at the time of vaginal delivery, which was complicated by clinical chorioamnionitis. The infant required nasal continuous positive airway pressure for apnea and began taking antibiotics for suspected sepsis. Her physical examination revealed mild hypotonia but was otherwise normal. At 16 hours of age, she developed clinical seizures confirmed by conventional EEG.
A 24-hour NP SARS-CoV-2 RT-PCR was negative, but SARS-CoV-2 IgG, combined (total) IgG, IgM, and IgA reactivity to a recombinant derivative of SARS-CoV-2 spike protein, inflammatory markers, and cytokines were markedly elevated. There was cerebrospinal fluid pleocytosis but no detectable viruses or bacteria. Brain magnetic resonance imaging at 3 months of age showed severe parenchymal atrophy and cystic encephalomalacia. The follow-up exam at 1 year of age showed microcephaly, abnormal neurologic examination with low axial tone, head lag, increased appendicular tone, hyperreflexia, clonus, and significant neurodevelopmental delay with inability to roll over or sit unsupported.
Placenta in both cases had thrombosis and recanalization of stem villous vessels, stromal fibrosis, and increased stromal karyorrhexis of the terminal villi. In both placentas immunofluorescence detected the presence of SARS-CoV-2-nucleocapsid protein and spike protein in the syncytiotrophoblast. Placental findings of thrombosis and apoptosis are associated with maternal-fetal vascular malperfusion and placental ischemia, resulting in deterioration of placental function.
Both placentas were also analyzed for inflammatory and modulating factors that directly or indirectly adversely affect the development of the fetal central nervous system. These findings were compared with two age- and gender-matched placentas of SARS-CoV-2 negative mothers.
The results showed a significant increase in inflammatory and oxidative stress markers: NLR family pyrin domain containing 1 (NLRP1), macrophage inflammatory protein 1β (MIP1-β ), stromal cell-derived factor 1, interleukin 13, and interleukin 10, compared with controls. The inflammation of the fetal-placental unit leads to the development of the fetal inflammatory response syndrome. This causes fetal hypoxia, blood-brain barrier compromise and fetal brain injury. Elevated levels of placental proinflammatory NLRP1, MIP1-β and IL-13 are known to impair fetal neurodevelopment.
In addition, placental human chorionic gonadotropin (hCG) was markedly reduced in the SARS-CoV-2 positive placentas, compared with controls. The placental hormone hCG promotes uterine angiogenesis and vasculogenesis to ensure adequate blood supply to the placenta. hCG also plays a neuroprotective role against hypoxic-ischemic neurodegeneration in the developing brain. Therefore, a decrease in hCG levels suggests a placental compromise.
Notably, previous morphometric analysis of the placental arteries in women who gave birth to live full-term newborns while developing COVID-19 during pregnancy showed severe thickening of the vascular wall and the occlusion of the vascular lumen. The results showed a twofold increase in wall thickness and a fivefold reduction in the lumen area. Immunohistochemistry demonstrated the association of such placental vascular remodelling with smooth muscle proliferation and fibrosis. https://discovermednews.com/the-s1-subunit-of-the-spike-protein-by-itself-may-promote-cell-signaling-in-the-vasculature/
Clinical findings, placental pathology, and immunohistochemical findings strongly suggest that second-trimester maternal SARS-CoV-2 infection with placentitis triggered an inflammatory response and oxidative stress injury to the feto-placental unit that affected the fetal brain. The changes observed in both placentas are sufficient to explain at least the initial neurological presentation of both infants.
SARS-CoV-2 was absent in the nasopharyngeal swabs of two newborns. However, elevated SARS-CoV-2 antibodies and proinflammatory mediators along with the neuropathology findings in the brain of the deceased infant, indicate that brain injury was caused either by the fetal inflammatory response to placental infection or/and by an undetected in utero brain infection.
Immunofluorescence detected S1 in both case placentas, colocalized with the nucleocapsid protein of the syncytiotrophoblast. Immunofluorescence also identified the S1 protein colocalized with the nucleocapsid protein throughout the brain of the deceased infant, which raises the possibility that SARS-CoV-2 infection of the fetal brain has directly contributed to brain damage.
The authors concluded that reported cases demonstrated that midtrimester maternal SARS-CoV-2 infection can infect the placenta and fetal brain. This subsequently triggers a cascade of inflammatory events in both placenta and fetus associated with severe brain lesions and progressive neurological sequelae.
This study was published in the scientific journal Pediatrics. Merline Benny, et al. Maternal SARS-CoV-2, Placental Changes and Brain Injury in 2 Neonates. Pediatrics 2023; e2022058271. (Open Access) https://doi.org/10.1542/peds.2022-058271