Sialylation status in placentas from pregnancies with SARS-CoV-2 infection

Introduction Recent investigations suggest the potential negative impact of SARS-CoV-2 infection on pregnant women and pregnancy outcome. In addition, some studies have described pathological changes in the placental tissue of SARS-CoV-2-positive mothers, which are related or not to the infection severity and/or infection trimester. Among the various molecules involved in the normal structure and functionality of the placenta, sialic acids (Sias) seem to play an important role. Hence, we aimed to investigate possible changes in the distribution and content of Sias with different glycosidic linkages, namely α2,3 and α2,6 Galactose- or N-acetyl-Galactosamine-linked Sias and polymeric Sia (PolySia), in placentas from pregnant women infected by SARS-CoV-2 during the three different pregnancy trimesters. Methods α2,3 and α2,6 Galactose-linked Sias were evaluated by lectin histochemistry (Maackia amurensis agglutinin (MAA) and Sambucus nigra agglutinin (SNA), respectively), while immunohistochemistry was used for PolySia detection. Results Data showed lower levels of α2,3 Galactose-linked Sias in the trophoblast and underlying basement membrane/basal plasma membrane in placentas from women infected during the second and third infection trimester compared with uninfected cases and those infected during first trimester. On the other hand, higher levels of PolySia were detected in the trophoblast during the second and third infection trimester. Conclusions Our findings suggest that changes in the sialylation status of trophoblast and its basement membrane/basal plasma membrane, together with other concomitant factors, could be at the basis of the most common placental histopathological alterations and gestational complications found especially in pregnancies with SARS-CoV-2 infection during the second and third trimester.

Sialylation status in placentas from pregnancies with SARS-CoV-2 infection.

INTRODUCTION: Recent investigations suggest the potential negative impact of SARS-CoV-2 infection on pregnant women and pregnancy outcome. In addition, some studies have described pathological changes in the placental tissue of SARS-CoV-2-positive mothers, which are related or not to the infection severity and/or infection trimester. Among the various molecules involved in the normal structure and functionality of the placenta, sialic acids (Sias) seem to play an important role. Hence, we aimed to investigate possible changes in the distribution and content of Sias with different glycosidic linkages, namely α2,3 and α2,6 Galactose- or N-acetyl-Galactosamine-linked Sias and polymeric Sia (PolySia), in placentas from pregnant women infected by SARS-CoV-2 during the three different pregnancy trimesters. METHODS: α2,3 and α2,6 Galactose-linked Sias were evaluated by lectin histochemistry (Maackia amurensis agglutinin (MAA) and Sambucus nigra agglutinin (SNA), respectively), while immunohistochemistry was used for PolySia detection. RESULTS: Data showed lower levels of α2,3 Galactose-linked Sias in the trophoblast and underlying basement membrane/basal plasma membrane in placentas from women infected during the second and third infection trimester compared with uninfected cases and those infected during first trimester. On the other hand, higher levels of PolySia were detected in the trophoblast during the second and third infection trimester. CONCLUSIONS: Our findings suggest that changes in the sialylation status of trophoblast and its basement membrane/basal plasma membrane, together with other concomitant factors, could be at the basis of the most common placental histopathological alterations and gestational complications found especially in pregnancies with SARS-CoV-2 infection during the second and third trimester.

SARS-CoV-2 Infection: A Clinical and Histopathological Study in Pregnancy.

During pregnancy, SARS-CoV-2 infection is associated with several adverse outcomes, including an increased risk of pre-eclampsia, preterm delivery, hypertensive disorders, gestational diabetes, and fetal growth restriction related to the development of placenta vascular abnormalities. We analyzed human placenta from full-term, uncomplicated pregnancies with SARS-CoV-2 infection during the first, second, or third trimesters of gestation. We studied, by the immunohistochemistry technique, the expression of CD34 and podoplanin (PDPN) as markers of vasculogenesis to find any differences. As secondary outcomes, we correlated maternal symptoms with placental histological alterations, including fibrin deposits, lymphocyte infiltration in the villi, edema, and thrombi. Our results showed a PDPN expression around the villous stroma as a plexiform network around the villous nucleus of fetal vessels; significant down-regulation was observed in the villous stroma of women infected during the third trimester. CD34 showed no changes in expression levels. During SARS-CoV-2 infection, the most common maternal symptoms were fever, anosmia, ageusia and asthenia, and the majority were treated with paracetamol, corticosteroids and azithromycin. Patients that required multiple symptomatic treatments evidenced a large amount of fibrin deposition in the villi. Certainly, PDPN plays a key role in healthy placental vasculogenesis and thus in its proper physiology, and SARS-CoV-2 surely alters its normal expression. Further studies are necessary to understand what mechanisms are being altered to try to avoid possible complications for both the mother and fetus in terms of the contagions that will still occur.

Incidence of gestational diabetes mellitus before and after the Covid-19 lockdown: A retrospective cohort study.

AIM: To evaluate whether the first Covid-19 lockdown for Italian citizens (March to July 2021) might have altered the incidence of gestational diabetes mellitus (GDM). METHODS: A retrospective single-center study in a tertiary referral center. Primary outcome was the incidence of GDM among pregnant women. GDM incidence, from June 11, 2019 to December 4, 2020, was compared by dividing the study time as follows: from the beginning of the study to before Covid-19 lockdown (from June 11, 2019, to March 9, 2020) and lockdown period (from March 10, 2020, to December 4, 2020). GDM was diagnosed with a 75-g, 2-h oral glucose tolerance test (OGTT) at 24-28 gestational weeks. RESULTS: Concerning 1295 women, GDM incidence increased during the lockdown period (9.3% vs. 3.4%, p < 0.001). Higher pregnancy weight gain with an increased body mass index (BMI) at the delivery was reported during the lockdown (31.3 vs. 28.4 kg/m2 , p = 0.02 and mean weight gain of 9.3 vs. 6.6 kg, p = 0.007). There was no difference in other comorbidity incidence and OGTT values between the two groups. CONCLUSIONS: Pregnant women during the Covid-19 lockdown might have experienced higher BMI and pregnancy weight gain with increased GDM diagnoses. This may be related to physical limitations and emotional distress experienced during the lockdown. However, evidence is limited due to restricted study duration and random variations of outcomes across time. More studies are needed to understand the dietary patterns and the physical activity changes during the Covid-19 lockdown and its impact on fetal outcomes.

Maternal death related to COVID-19: A systematic review and meta-analysis focused on maternal co-morbidities and clinical characteristics.

BACKGROUND: Besides reducing the quality of obstetric care, the direct impact of COVID-19 on pregnancy and postpartum is uncertain. OBJECTIVE: To evaluate the characteristics of pregnant women who died due to COVID-19. SEARCH STRATEGY: Cochrane Library, Embase, MEDLINE, Scopus, and Google Scholar were searched from inception to February 2021. SELECTION CRITERIA: Studies that compared deceased and survived pregnant women with COVID-19. DATA COLLECTION AND ANALYSIS: Relevant data were extracted and tabulated. The primary outcome was maternal co-morbidity. MAIN RESULTS: Thirteen studies with 154 deceased patients were included. Obesity doubled the risk of death (relative risk [RR] 2.48, 95% confidence interval [CI] 1.41-4.36, I2  = 0%). No differences were found for gestational diabetes (RR 5.71; 95% CI 0.77-42.44, I2  = 94%) or asthma (RR 2.05, 95% CI 0.81-5.15, I2  = 0%). Overall, at least one severe co-morbidity showed a twofold increased risk of death (RR 2.26, 95% CI 1.77-2.89, I2  = 76%). Admission to intensive care was related to a fivefold increased risk of death (RR 5.09, 95% CI 2.00-12.98, I2  = 56%), with no difference in need for respiratory support (RR 0.53, 95% CI 0.23-1.48, I2  = 95%) or mechanical ventilation (RR 4.34, 95% CI 0.96-19.60, I2  = 58%). CONCLUSION: COVID-19 with at least one co-morbidity increases risk of intensive care and mortality.