SARS-CoV-2, Placental Histopathology, Gravity of Infection and Immunopathology: Is There an Association?

Abstract

(1) Background: As the pandemic months progress, more and more evidence shows that the placenta acts as a “barrier” to SARS-CoV-2, although rare cases of vertical transmission have been described. (2) Methods: In an attempt to investigate whether the symptoms’ severity was related to different placental histological characteristics and the immune microenvironment, we subdivided 29 placentas from 29 mothers positive for SARS-CoV-2 into two groups, depending on the symptomatology (moderate/severe vs. asymptomatic/mild), performing immunohistochemical investigations for CD4 + and CD8 + T lymphocytes, as well as for CD68 + macrophage. We also evaluated the immuno-expression of the ACE2 receptor at the placental level. These two groups were compared to a control group of 28 placentas from 28 SARS-CoV-2-negative healthy mothers. (3) Results: The symptoms (likely to be related to viremia) were statistically significantly correlated (p < 0.05) with histopathological changes, such as maternal malperfusion, decidual arteriopathy, blood vessel thrombus of fetal relevance. Furthermore, the immuno-expression of ACE2 was significantly lower in SARS-CoV-2-positive groups vs. control group (p = 0.001). (4) Conclusions: There is still much to study and discover regarding the relationship between SARS-CoV-2 and histological changes in placentas and how the latter might contribute to various neonatal clinical outcomes, such as prematurity.