Yuichiro Shinmura

Cytomegalovirus Infection of the Central Nervous System Stem Cells from Mouse Embryo: A Model for Developmental Brain Disorders Induced by Cytomegalovirus

Cytomegalovirus (CMV) is the most frequent infectious cause of developmental disorders of the central nervous system (CNS) in humans. Infection of the CNS stem cells seems to be primarily responsible for the generation of the brain abnormalities. In this study, we evaluated the infectivity of murine CMV (MCMV) in epidermal growth factor (EGF)-responsive CNS stem cells prepared from fetal mouse brains, and studied the effect of infection on growth and differentiation of the stem cells. The CNS stem cells were permissive for MCMV infection, although MCMV replication was slower than in mouse embryonic fibroblasts. MCMV infection inhibited the growth and DNA replication of the stem cells. A clonogenic assay revealed that MCMV infection suppressed generation of colonies from single stem cells. When uninfected stem cells were induced to differentiate, a decrease in expression of the primitive neuroepidermal marker nestin was observed by immunocytochemistry and flow cytometry, whereas expression of neurofilament and glial fibrillary acidic protein (GFAP) were induced. In virus-infected CNS stem cells, nestin expression was retained, whereas the expression of neurofilament was more severely inhibited than that of GFAP in these cells. Two-color flow cytometry showed that differentiated glial precursor cells were preferentially susceptible to MCMV infection. MCMV-infected and uninfected CNS stem cells were transplanted into the neonatal rat brains. The reduced number of infected stem cells were engulfed into the subventricular zone and expressed GFAP, but did not migrate further, in contrast to the uninfected stem cells. These results suggest that suppression of the growth of the CNS stem cells and inhibition of the neuronal differentiation by CMV infection may be primary causes of disorders of brain development in congenital CMV infection.

Disordered migration and loss of virus-infected neuronal cells in developing mouse brains infected with murine cytomegalovirus

Abstract Microcephaly is the most prominent symptom of the developmental brain abnormalities induced by congenital cytomegalovirus (CMV) infection. To investigate the effect of CMV infection on neuronal migration in developing brains, mouse embryos on one side of uteri received, on day 15.5 of gestation (E15.5), an injection of murine CMV (MCMV) into the cerebral ventricles, and the embryos on the other side of the uteri were injected with minimum essential medium (MEM). Labeling with 5-bromo-2-deoxyuridine (BrdU) was accomplished by intraperitoneal injection of BrdU 6 h later. Disturbance of the neuronal migration and loss of neurons were observed postnatally in the brains of MCMV-infected mice, which were identified by immunohistochemical staining of viral antigen. Double staining of BrdU-labeled and viral antigen-positive cells in brains on the 7th postnatal day showed that the migration of BrdU-single-labeled cells mainly localized in cerebral layers II–III, mostly preceded that of the viral antigen-positive cells. However, about 7.5% of the cells observed were double-labeled, especially in the layers III–IV, and a few double-stained cells were markedly disturbed in migration. In the brains of offspring labeled with BrdU 72 h after infection with MCMV on E15.5, most of the double-stained cells were seen around the ventricular and subventricular zones. These findings suggest that a disturbance of neuronal migration in addition to neuronal loss may play a crucial role in the development of microcephaly in congenital CMV infection in humans.

A case of clear cell adenocarcinoma of the müllerian duct in persistent müllerian duct syndrome: the first reported case.

We report a case of a 67-year-old man with clear cell adenocarcinoma of the remnant uterus in persistent Müllerian duct syndrome. He had a normal penis, urethra, and scrotum, and there was also a vagina and uterus. He died in a traffic accident, and clear cell adenocarcinoma was discovered incidentally at autopsy. Clear cell adenocarcinoma of the remnant uterus metastasized to the retroperitoneal lymph nodes and bilateral lungs. Persistent Müllerian duct syndrome is characterized by the persistence of Müllerian derivatives in otherwise normally virilized males. A variety of germ cell tumors of the testis have been reported in association with persistent Müllerian duct syndrome. However, no malignant change of the persistent Müllerian duct structures has been reported. This represents the first reported case of malignant change of the persistent Müllerian duct structures in persistent Müllerian duct syndrome.

Murine cytomegalovirus induces apoptosis in non-infected cells of the developing mouse brain and blocks apoptosis in primary neuronal culture

Abstract Cytomegalovirus (CMV) is the most common cause of congenital infection, resulting in birth defects such as microcephaly. In this study, we found that apoptosis is induced in the developing mouse brain infected with murine cytomegalovirus (MCMV) in an association with neuronal cell loss. With the combination of the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) technique and immunohistochemical staining, 3.8% of the TUNEL-positive cells were double-stained with the antibody to neuron-specific enolase, while none of the TUNEL-positive cells were stained with antibodies to the immediate early and early viral antigens of MCMV. Furthermore, distribution pattern of the TUNEL-positive cells was different from that of viral DNA-positive cells detected by the in situ DNA-DNA hybridization. More than 30% of the TUNEL-positive cells were double-stained with the F4/80 antibody specific for microglia/macrophages, which were sometimes swollen, presumably the consequence of engulfment of the neuronal apoptotic cells. In the primary neuronal cultures, MCMV infection inhibited the induction of apoptosis either by serum deprivation or by glutamate treatment. It was also confirmed by the double-staining method that apoptosis was not induced in the viral-infected neuronal cultures. These results suggest that MCMV infection induces apoptosis in non-infected neuronal cells, presumably by indirect mechanisms, and that apoptotic cells are engulfed by microglia/macrophages. The induction and blocking of neuronal apoptosis by viral infection may be important for morphological and functional brain disorders in the congenital CMV infection.

Murine Cytomegalovirus Immediate-Early Promoter Directs Astrocyte-Specific Expression in Transgenic Mice

Murine cytomegalovirus (MCMV), which causes acute, latent, and persistent infection of the natural host, is used as an animal model of human cytomegalovirus (HCMV) infection. Transcription of MCMV immediate-early (IE) genes is required for expression of the early and late genes and is dependent on host cell transcription factors. Cell-type-specific expression activity of the MCMV IE promoter was analyzed in transgenic mice generated with the major IE (MIE) enhancer/promoter involving nucleotides -1343 to -6 (1338 bp) connected to the reporter gene lacZ. Distinct expression was observed in the brain, kidneys, stomach, and skeletal muscles. Weak expression was observed in a portion of the parenchymal cells of the salivary glands and pancreas, and expression was hardly detected in the lungs, intestine, or immune and hematopoietic organs such as the thymus, spleen, lymph nodes, and bone marrow. The spectrum of organs positive for expression was narrower than that of the HCMV MIE promoter-lacZ transgenic mice reported previously and showed a greater degree of cell-type specificity. Interestingly, astrocyte-specific expression of the transgene was observed in the brain and primary glial cultures from the transgenic mice by combination of beta-galactosidase (beta-Gal) expression and immunostaining for cell markers. However, the transgene was not expressed in neurons, oligodendroglia, microglia, or endothelial cells. Furthermore, the beta-Gal expression in glial cultures was stimulated significantly by MCMV infection or by addition of calcium ionophore. These observations indicated that expression activity of the MCMV IE promoter is strictly cell-type specific, especially astrocyte-specific in the brain. This specific pattern of activity is similar to that of natural HCMV infection in humans.

Activation of murine cytomegalovirus immediate‐early promoter in cerebral ventricular zone and glial progenitor cells in transgenic mice

Cytomegalovirus (CMV) is the most common infectious cause of congenital anomalies of the CNS in humans. We recently reported that the murine cytomegalovirus (MCMV) immediate‐early (IE) gene promoter directs astrocyte‐specific expression in adult transgenic mice. In the present study, we analyzed the activation of the MCMV IE promoter in developing transgenic mouse brains and compared the activation with that of the Musashi 1 (Msi1) gene, which is expressed in neural progenitor cells, including neural stem cells. During the early phase of neurogenesis, the transgene was expressed predominantly in endothelial cells of the vessels, but not in neuroepithelial cells in which Msi1 was expressed. During later stages of gestation, expression of the transgene was largely restricted to the ventricular zone (VZ) in the CNS, similar to the expression of Msi1. In neurosphere cultures from transgenic embryos in the late phase of neurogenesis, the transgene was expressed in some cells of neurospheres expressing Msi1 and nestin. In neural precursor cells induced to differentiate from stem cells, expression of the transgene was detected in glial progenitor cells, expressing GFAP, nestin, and Msi1, but not in cells expressing MAP2 or MAG. In postnatal development, persistent expression of the transgene was observed in astrocyte lineage cells as was Msi1. These spatiotemporal changes of the MCMV IE promoter activity during development of transgenic mice correlated with susceptible sites in congenital HCMV infection. Moreover, this transgenic mouse model may provide useful model for analysis of the regulation of the switching of neuronal and astrocyte differentiation, and the maintenance of the astrocyte lineage. GLIA 35:41–52, 2001.

Migration of virus-infected neuronal cells in cerebral slice cultures of developing mouse brains after in vitro infection with murine cytomegalovirus

Abstract To investigate the effect of murine cytomegalovirus (MCMV) infection on the developing mouse brain in vitro, we developed an infection system using cerebral slice cultures. Using a micromanipulator, the cerebral slices from mouse embryos on day 18.5 of gestation were injected in the subventricular zone with recombinant MCMV in which the lacZ gene was inserted into a late gene, and were cultured for 7 days. Viral infection, detected by β-galactosidase reaction, was developed at the injection sites of the slices. The virus-infected spots in the slices were enhanced by adding tumor necrosis factor-α to the medium and inhibited by adding phosphonoacetic acid or ganciclovir. Sections from paraffin-embedded slices were subjected to immunohistochemical analyses. Neuronal cells, labeled with 5-bromo-2-deoxyuridine 24 h before cutting the slices, migrated to the cerebral cortex in the slices. Virus-infected neuronal cells expressing only the early viral antigen migrated to the cortex, whereas glial cells expressing the immediate early and late antigens tended to remain at the injected sites. The neuronal migration of infected cells was not observed in the cerebral slices from 7-day-old mice and viral infection was not detected after injection in the cerebral slices from 14- and 21-day-old mice. These results from these cerebral slices may reflect the infectious dynamics in vivo, and this system may provide a useful model for analysis of disorders of brain development caused by CMV.

Autopsy case of the cerebellar form of progressive multifocal leukoencephalopathy without immunodeficiency

A case of the cerebellar form of progressive multifocal leukoencephalopathy (PML) without remarkable immune depression or immune deficiency is reported here. The patient was a 74‐year‐old‐woman who had complications of chronic renal failure and renal anemia for several years. Seven months before her death she had symptoms of general fatigue, gait disturbance and articulation disorder. During her hospitalization period her neurological disorder gradually progressed irreversibly with failure of consciousness and she died of respiratory failure. She did not have remarkable clinical signs of immunodeficiency nor did she receive immunosuppressive therapy. Clinically she had not been diagnosed with PML. At the post‐mortem examination different degrees of demyelination were observed in the brain white matter: diffuse and severe in the cerebellum, moderate and coalescent in the brainstem, and light and patchy in the cerebrum. JC virus antigen‐positive cells were frequently observed in the demyelinated lesions in the cerebrum and sometimes observed in the brainstem, but were rarely found in the cerebellum. These findings suggest that PML lesions may be present with different degrees of demyelination that are inversely correlated with the number of JC virus‐infected cells. This fact should be considered when evaluating the brain biopsies of PML patients.

Sacrococcygeal chordoma in infancy showing an aggressive clinical course: an autopsy case report.

The autopsy case of a 3‐year 6‐month‐old boy with chordoma arising in the sacrococcygeal region is presented. The primary lesion of the sacrococcygeal area was unresectable and lung metastasis was detected. He was treated with multi‐agent systemic chemotherapy and radiation therapy, but the tumor was less responsive to these therapies. He died about one year after first admission. An autopsy revealed a massive sacrococcygeal mass and metastasis in the thoracic and lumbar vertebrae, retroperitoneal and mediastinal lymph nodes, and also in the bilateral lungs and liver. Histologically, the tumor was composed of ‘pink’ cells and scattered ‘physaliphorous’ cells with a myxoid matrix. Sacrococcygeal chordoma in infancy is very rare. Our case showed a highly aggressive clinical course.

Effects of intrapulmonary viral tropism and cytokine expression on the histological patterns of cytomegalovirus pneumonia

Pulmonary cytomegalovirus (CMV) infection causes fatal CMV pneumonia (CMVp) in immunocompromised patients; however, the mechanisms underlying CMV‐infection‐induced pulmonary lesion development remain largely unknown. We examined the relationship between CMVp patterns and intrapulmonary viral tropism, including expression of inflammatory cytokines and related molecules. Double immunohistochemistry of CMV antigen and cellular markers showed that epithelial tropism was associated with a diffuse alveolar damage (DAD) pattern (CMVp‐DAD) while stromal tropism was associated with a predominantly interstitial inflammation/fibrosis (IIF) (CMVp‐IIF) or a combination of DAD and IIF (CMVp‐complex). Transforming growth factor (TGF)‐β1 expression was relevant to CMV‐induced tissue injury, and its expression was higher in CMVp‐complex and CMVp‐IIF than in CMVp‐DAD. Expression of integrin β6 (ITGB6), an adhesion molecule and important activator of TGF‐β1 in interstitial pneumonia, was lost in CMV‐infected pneumocytes, especially CMVp‐DAD, whereas CMV‐negative pneumocytes in CMVp‐complex and CMVp‐IIF showed overexpression. Diffuse interleukin (IL)‐8 up‐regulation and strong expression were present in both CMV‐infected pneumocytes and stromal cells only in CMVp‐IIF cases with marked interstitial neutrophilic infiltration. On the basis of viral tropism and the expression of TGF‐β1, ITGB6, and IL‐8, we conclude that CMV‐infected pulmonary cells play an important role in the development of diverse CMVp patterns.