Subamniotic haemorrhage, a possible new presentation of fetal and neonatal alloimmune thrombocytopenia

Background: Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a rare fetal disease in which maternal antibodies directed towards fetal human platelet antigens (HPA) are formed during pregnancy and cause fetal thrombocytopenia. The diagnosis FNAIT is suspected when a fetus or neonate presents with signs of bleeding. Case: We describe a pregnancy complicated by a placental hematoma in the 20th week of gestation as the first manifestation of FNAIT. Further evaluation showed signs of germinal matrix haemorrhage and HPA-5b allo-antibodies. After the diagnosis, intravenous immunoglobulin was administered weekly and a healthy daughter was born at 37 weeks. Histopathological analysis revealed that the hematoma was caused by a subamniotic haemorrhage of fetal origin. Conclusion: A subamniotic hematoma appears to be the first manifestation of FNAIT.

FETAL ORIGIN OF ADULT DISEASE

“Fetal origins of adult disease”, often called the “Barker hypothesis” after a large proportion data of Barker and colleagues in Southampton over the last decade, that adverse influences early in development, and particularly during intrauterine life, can result in permanent changes in structure, physiology, metabolism, which result in increased disease risk in adulthood. Many further studies have provided evidence for the hypothesis that size at birth is related to the risk of developing disease in later life. In particular, links are well established between reduced birthweight and increased risk of coronary heart disease, diabetes, hypertension and stroke in adulthood. The most widely accepted mechanisms thought to underlie these relationship are those of altered fetal nutrition, genetic–epigenetic links, fetal programming and fetal excess glucocorticoid exposure. It is suggested that the fetus makes physiological adaption in response to changes in its environment to prepare itself for posnatal life. The “Fetal origin of adult disease” hypothesis is attractive. It suggests that these diseases could be prevented by improving maternal health and fetal development

Fetal Origin of Placental Hepatic Nodule

Intraplacental hepatic nodules are extremely rare and range from incidentally identified microscopic nodules to large mass-forming lesions. We describe the case of an incidentally identified intraparenchymal hepatic nodule in the placenta from a near-term delivery of a male infant at 36 weeks gestation. Lesional cells were positive for HepPar1, focally positive for glypican3, and negative for calretinin and alpha-fetoprotein, supportive of hepatocellular origin. Fluorescence in-situ hybridization and chromosomal microarray both showed a male sex chromosome complement (XY) within the nodule, confirming the fetal origin of this nodule. We provide the first report of the confirmed fetal origin of these rare lesions, lending support to the hypothesis that placental hepatic nodules may represent an embryonal rest or residua of abnormal cell migration.

Abstract 16446: Human Mesenchymal Stem Cells of Adult and Fetal Origin Do Not Express ACE2 and are Immune to SARS-CoV-2 Spike Pseudotyped Virus

Background: Angiotensin-converting enzyme 2 (ACE2) expression in the lung has a protective role against injury. However, ACE2 is the main host cell receptor for the Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) entry. Human mesenchymal stem cells (hMSCs) are currently under investigation for the treatment of pulmonary and cardiac complications of the SARS-CoV-2 disease (COVID-19). However, it is unclear if hMSCs express ACE2 and if they possibly can secrete ACE2. Also, their predisposition to be infected by SARS-CoV-2 is unknown. Aim: To assess if hMSCs of fetal and adult origin constitutively express and secrete ACE2 and if they can be infected by SARS-CoV-2. Methods: We studied 8 hMSC lines: 4 of fetal origin isolated from human placentas (hA-MSC) and 4 of adult origin isolated from bone marrow aspirates (hBM-MSCs). The lung epithelial cancer cell line CALU-3, which expresses high levels of ACE2, was used as positive control. ACE2 expression was evaluated in both standard culture conditions and after 48 hrs of hypoxia exposure (1% O 2 ). We quantified the mRNA levels by RT-qPCR and verified protein content by western blot on both cell lysates and serum-free 48 hrs-conditioned media (MSC-CM). ACE2 levels in MSC-CM were quantified by ELISA assay. Finally, to test MSC viral susceptibility, we produced replication-defective, GFP-tagged retroviral particles bearing the SARS-CoV-2 Spike protein; the pantropic VSV glycoprotein (VSV-G) was used as positive control. Results: ACE2 mRNA level in both fetal and adult MSC was 200-fold lower than in CALU-3. ACE2 protein expression was undetectable in MSC lysates and CM, both by western blot and ELISA. Hypoxia slightly increased ACE2 mRNA level, but not protein level, which still was undetectable. Finally, CALU-3 but not MSC were infected by SARS-CoV-2 Spike pseudovirus, whereas both cell types were susceptible to VSV-G pseudovirus infection. Conclusions: Both fetal and adult MSC do not express significant levels of ACE2 both under normoxia and hypoxia, and therefore the putative therapeutic mechanism of hMSCs in COVID-19 cannot go through the release of ACE2. Importantly, MSCs are immune to SARS-CoV-2 infection and therefore their use appears safe.

RNA Sequencing Reveals Diverse Functions of Amniotic Fluid Neutrophils and Monocytes/Macrophages in Intra-Amniotic Infection

Intra-amniotic infection, the invasion of microbes into the amniotic cavity resulting in inflammation, is a clinical condition that can lead to adverse pregnancy outcomes for the mother and fetus as well as severe long-term neonatal morbidities. Despite much research focused on the consequences of intra-amniotic infection, there remains little knowledge about the innate immune cells that respond to invading microbes. We performed RNA-seq of sorted amniotic fluid neutrophils and monocytes/macrophages from women with intra-amniotic infection to determine the transcriptomic differences between these innate immune cells. Further, we sought to identify specific transcriptomic pathways that were significantly altered by the maternal or fetal origin of amniotic fluid neutrophils and monocytes/macrophages, the presence of a severe fetal inflammatory response, and pregnancy outcome (i.e., preterm or term delivery). We show that significant transcriptomic differences exist between amniotic fluid neutrophils and monocytes/macrophages from women with intra-amniotic infection, indicating the distinct roles these cells play. The transcriptome of amniotic fluid immune cells varies based on their maternal or fetal origin, and the significant transcriptomic differences between fetal and maternal monocytes/macrophages imply that those of fetal origin exhibit impaired functions. Notably, transcriptomic changes in amniotic fluid monocytes/macrophages suggest that these immune cells collaborate with neutrophils in the trafficking of fetal leukocytes throughout the umbilical cord (i.e., funisitis). Finally, amniotic fluid neutrophils and monocytes/macrophages from preterm deliveries display enhanced transcriptional activity compared to those from term deliveries, highlighting the protective role of these cells during this vulnerable period. Collectively, these findings demonstrate the underlying complexity of local innate immune responses in women with intra-amniotic infection and provide new insights into the functions of neutrophils and monocytes/macrophages in the amniotic cavity.