Fetal Brain Damage in Human Fetuses with Congenital Cytomegalovirus Infection: Histological Features and Viral Tropism

Abstract

Human cytomegalovirus (HCMV) causes congenital neurological lifelong disabilities. To date, the neuropathogenesis of brain injury related to congenital HCMV (cCMV) infection is poorly understood. This study evaluates the characteristics and pathogenetic mechanisms of encephalic damage in cCMV infection. Ten HCMV-infected human fetuses at 21 weeks of gestation were examined. Specifically, tissues from different brain areas were analyzed by: (i) immunohistochemistry (IHC) to detect HCMV-infected cell distribution, (ii) hematoxylin–eosin staining to evaluate histological damage and (iii) real-time PCR to quantify tissue viral load (HCMV-DNA). The differentiation stage of HCMV-infected neural/neuronal cells was assessed by double IHC to detect simultaneously HCMV-antigens and neural/neuronal markers: nestin (a marker of neural stem/progenitor cells), doublecortin (DCX, marker of cells committed to the neuronal lineage) and neuronal nuclei (NeuN, identifying mature neurons). HCMV-positive cells and viral DNA were found in the brain of 8/10 (80%) fetuses. For these cases, brain damage was classified as mild (n = 4, 50%), moderate (n = 3, 37.5%) and severe (n = 1, 12.5%) based on presence and frequency of pathological findings (necrosis, microglial nodules, microglial activation, astrocytosis, and vascular changes). The highest median HCMV-DNA level was found in the hippocampus (212 copies/5 ng of human DNA [hDNA], range: 10–7,505) as well as the highest mean HCMV-infected cell value (2.9 cells, range: 0–23), followed by that detected in subventricular zone (1.7 cells, range: 0–19). These findings suggested a preferential viral tropism for both neural stem/progenitor cells and neuronal committed cells, residing in these regions, confirmed by the expression of DCX and nestin in 94% and 63.3% of HCMV-positive cells, respectively. NeuN was not found among HCMV-positive cells and was nearly absent in the brain with severe damage, suggesting HCMV does not infect mature neurons and immature neural/neuronal cells do not differentiate into neurons. This could lead to known structural and functional brain defects from cCMV infection. Graphical Abstract

Development of the Prosencephalic Structures, Ganglionic Eminence, Basal Ganglia and Thalamus at 11+3 to 13+6 Gestational Weeks on 3D Transvaginal Ultrasound Including Normative Data

“…This study should be seen as a basis for clarifying the diagnostic criteria of pathologic changes in the presented structures, pathologies of migration (lissencephaly, polymicrogyria, early severe CMV infections [24]), dysplasia of the thalamus (mild forms of holoprosencephaly [2]) and dysplasia of the basal ganglia (polymicrogyria). After primary detection of abnormalities in transabdominal ultrasound experienced sonographers could in a second step by targeted transvaginal 3D ultrasound analyze the details of the prosencephalic structures to evaluate different pathologic entities.…”

The Auditory Pathway in Congenitally Cytomegalovirus-Infected Human Fetuses

“…Histological studies, carried out in congenitally infected fetuses and children, have shed light on the pathophysiology of CMV infection [ 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. CMV-positive cells might be found in any cerebral region (leptomeninges, cortex, white matter, germinal matrix, or grey matter) and any kind of cells might be infected (neurons, neuroblasts, glia, endothelial, ependymal, and meningeal).…”

“…CMV-positive cells might be found in any cerebral region (leptomeninges, cortex, white matter, germinal matrix, or grey matter) and any kind of cells might be infected (neurons, neuroblasts, glia, endothelial, ependymal, and meningeal). Especially in fetuses with severe cerebral injuries [ 14 , 16 ], cortical damage included laminar necrosis, in which the third layer was wiped out and replaced by macrophages, and early polymicrogyria, with abnormal infoldings of the developing sulci. In the white matter, periventricular leukomalacia, capillary proliferation with plump endothelium, glial karyorrhexis, macrophage infiltration, microglial nodules with activated T-lymphocytes, and ferruginated neurons (i.e., deposition of iron and calcium in neuronal cell body, axons, and dendrites) were the most common neuropathological features.…”

“…Fetal cerebral damage is thus a combination of multiple injuries. Remarkably, CMV has been found to have a preferential tropism for neural stem/progenitor cells and neuronal committed cells, leading to impaired migration resulting in lissencephaly and/or polymicrogyria [ 16 ].…”

Human Cytomegalovirus Induces Significant Structural and Functional Changes in Terminally Differentiated Human Cortical Neurons

“…Previous reports demonstrate that HCMV can infect several resident cell types within the CNS, including astrocytes (14)(15)(16), oligodendrocytes (17), and neural progenitor cells (NPCs) (7,(18)(19)(20)(21). However, the ability of neurons to act as a susceptible target of HCMV infection is often debated, with empirical results ranging from no detected infectivity to full permissiveness (14,(20)(21)(22)(23)(24)(25). Among those demonstrating a lack of HCMV infection within neurons, the cells' post-mitotic state is commonly indicated to be the underlying reason (14).…”