Antigens of monoclonal antibody NB3C4 are novel markers for oligodendrocytes

Natalizumab has no direct biological effect on JC virus infectivity in permissive human neural cell lines

The human polyomavirus JC virus (JCV) infects 70-80% of humans and establishes latent infection in the kidney. In immunosuppressed patients, JCV reactivates and causes a fatal and progressive neurological disease known as progressive multifocal leukoencephalopathy (PML). Over the past three decades, PML has become an important neurological complication in acquired immunodeficiency syndrome (AIDS) patients. Recently, it was reported that patients treated with therapeutics that target the integrin receptor very late antigen (VLA)-4 are at increased risk of developing PML. However, the relationship between Natalizumab and this unexpected onset of PML has yet to be elucidated. Here, we investigated the effect of Natalizumab on the growth of JCV in the permissive human neural cell line IMR-32 following viral inoculation. Natalizumab had no effect either on the expression levels of viral proteins as determined by immunoblot analysis using specific antibodies or on the hemagglutination activity of cellular lysates from infected cells. These results suggest that there is no direct effect of Natalizumab on JCV infectivity in IMR-32 cells in vitro.

Suppression of proinflammatory cytokine production in macrophages by lansoprazole

Macrophages (MPs) produce increased levels of proinflammatory cytokines in Crohn's disease; these cytokines are thought to play a central role in the occurrence of the disease. Biologics are currently available for anti-cytokine therapy, but treating intestinal inflammation through direct suppression of proinflammatory cytokine production could be more effective. P-ATPase inhibitors have been reported to be anti-inflammatory, and these inhibitors might suppress the production of MP proinflammatory cytokines. In this study, we examined the effect of two types of ATPase inhibitors on the expression patterns of typical proinflammatory cytokines. Peritoneal MPs from 6- to 8-week-old mice were cultured for 48 h in the presence of lansoprazole (P-ATPase inhibitor), bafilomycin A(1) (V-ATPase inhibitor), or the control solvent dimethylsulfoxide. The MPs were then examined for cytokine expression by quantitative real-time polymerase chain reaction (PCR), and culture supernatants were examined for cytokine production with a multiplex assay in a suspension array system. The possible existence of P-ATPase mRNA in MPs was explored using reverse-transcriptase PCR. P-ATPase mRNA was not detected in MP cells. However, all examined proinflammatory cytokines decreased significantly in their mRNA and protein expression in the lansoprazole-treated group. Conversely, bafilomycin A(1) increased the levels of these cytokines. Lansoprazole might be useful for the treatment of inflammatory bowel diseases (IBDs), including Crohn's disease, as it suppresses the production of relevant MP proinflammatory cytokines. However, because P-ATPase was not detected in MPs, the mechanism is unclear and remains to be studied further in an IBD animal model.

Establishment of an immunoscreening system using recombinant VP1 protein for the isolation of a monoclonal antibody that blocks JC virus infection

Polyomavirus JC (JCV) infection causes the fatal human demyelinating disease, progressive multifocal leukoencephalopathy. Although the initial interaction of JCV with host cells occurs through direct binding of the major viral capsid protein (VP1) with cell-surface molecules possessing sialic acid, these molecules have not yet been identified. In order to isolate monoclonal antibodies which inhibit attachment of JCV, we established an immunoscreening system using virus-like particles consisting of the VP1. Using this system, among monoclonal antibodies against the cell membrane fraction from JCV-permissive human neuroblastoma IMR-32 cells, we isolated a monoclonal antibody designated as 24D2 that specifically inhibited attachment and infection of JCV to IMR-32 cells. The antibody 24D2 recognized a single molecule of around 60 kDa in molecular weight in the IMR-32 membrane fraction. Immunohistochemical staining with 24D2 demonstrated immunoreactivity in the cell membrane of JCV-permissive cell lines and glial cells of the human brain. These results suggested that the molecule recognized by 24D2 plays a role in JCV infection, and that it might participate as a receptor or a co-receptor in JCV attachment and entry into the cells.

Upregulation of oligodendrocyte progenitor cells associated with restoration of mature oligodendrocytes and myelination in peri-infarct area in the rat brain

This study examines the alteration of oligodendrocyte progenitor cells (OPCs), mature oligodendrocytes (OLGs) and myelination after focal ischemia in the rat brain. Adult male Sprague-Dawley rats were subjected to 90-min occlusion of the middle cerebral artery, followed by reperfusion time of up to 2 weeks. The infarct core showed a rapid and progressive decrease in the number of OPCs, OLGs, as well as the myelin density after 48 h of recirculation. The peri-infarct area exhibited a moderate reduction in the number of OLGs and the myelin density with a slight increase in the number of OPCs at 48 h of recirculation. Subsequently, a steady increase in the number of OPCs and a gradual recovery of the number of OLGs were noted in the peri-infarct area, which were accompanied by a gradual restoration of the myelin density, resulting in almost complete recovery of myelin density at 2 weeks of recirculation. OPCs in the peri-infarct area showed characteristic morphological changes such as mitotic figures, monopolar or bipolar shapes, and hypertrophied cell bodies and processes, all indicating active cell proliferation and migration. These findings suggest that the upregulation of OPCs may contribute to replenishment of OLGs and resultant remyelination in the peri-infarct area after ischemic insult.