Thymic Alterations in GM2 Gangliosidoses Model Mice

BACKGROUND: Sandhoff disease is a lysosomal storage disorder characterized by the absence of β-hexosaminidase and storage of GM2 ganglioside and related glycolipids. We have previously found that the progressive neurologic disease induced in Hexb(-/-) mice, an animal model for Sandhoff disease, is associated with the production of pathogenic anti-glycolipid autoantibodies. METHODOLOGY/PRINCIPAL FINDINGS: In our current study, we report on the alterations in the thymus during the development of mild to severe progressive neurologic disease. The thymus from Hexb(-/-) mice of greater than 15 weeks of age showed a marked decrease in the percentage of immature CD4(+)/CD8(+) T cells and a significantly increased number of CD4(+)/CD8(-) T cells. During involution, the levels of both apoptotic thymic cells and IgG deposits to T cells were found to have increased, whilst swollen macrophages were prominently observed, particularly in the cortex. We employed cDNA microarray analysis to monitor gene expression during the involution process and found that genes associated with the immune responses were upregulated, particularly those expressed in macrophages. CXCL13 was one of these upregulated genes and is expressed specifically in the thymus. B1 cells were also found to have increased in the thy mus. It is significant that these alterations in the thymus were reduced in FcRγ additionally disrupted Hexb(-/-) mice. CONCLUSIONS/SIGNIFICANCE: These results suggest that the FcRγ chain may render the usually poorly immunogenic thymus into an organ prone to autoimmune responses, including the chemotaxis of B1 cells toward CXCL13

Induction of epithelial migration of lymphocytes by intercellular adhesion molecule-1 in a rat model of oral mucosal graft-versus-host disease

To elucidate the involvement of intercellular adhesion molecule-1 (ICAM-1) in the migration of lymphocytes to the oral mucosal epithelium in a rat model of acute graft-versus-host disease (AGVHD), we investigated (1) ICAM-1 and major histocompatibility complex (MHC) class II expression by keratinocytes (KCs) and their role in the epithelial infiltration of CD8+ cells, (2) the tissue expression of interferon-γ (IFN-γ) mRNA and expression of IFN-γ receptor by KCs, and (3) the ability of KCs to direct CD8+ cells into the epithelial layers. We classified the oral mucosal lesions into three consecutive temporal phases on the basis of increased epithelial ICAM-1expression: basal- (phase I), parabasal- (phase II), and pan-epithelial except for the cornified cell layer (phase III). Basal ICAM-1 expression by KCs preceded that of MHC class II molecules, infiltration of CD8+ cells and epithelial histological changes. Tissue expression of IFN-γ mRNA and expression of IFN-γ receptor on KCs evidenced by immunohistochemistry were detected in early lesions (phase I), indicating that locally produced IFN-γ induced ICAM-1 expression by KCs. CD8+ cells were bound to KCs in frozen sections of epithelial lesions, whereas no lymphocyte attachment was observed in normal KC. Adherence could be inhibited by pretreating CD8+ cells with lymphocyte function-associated antigen-1 (LFA-1) antibody and/or by pretreating sections with ICAM-1 antibody. Our data suggest that in the early phase of acute oral mucosal GVHD, the induction of ICAM-1 expression on KCs leads to the migration of CD8+ cells into the epithelium and that this is mediated in part by the ICAM-1/LFA-1 pathway

Mineral Trioxide Aggregate (MTA) Upregulates the Expression of DMP1 in Direct Pulp Capping in the Rat Molar

Mineral trioxide aggregate (MTA) is an alternative endodontic material that predicts conductive or inductive calcified tissue formation from immature pulp mesenchymal stem cells (IPMSCs). The purpose of this study was to investigate whether MTA could promote reparative odontoblast differentiation via IPMSCs in the early phase of regeneration and compare with calcium hydroxide (CH). Direct pulp capping using calcium hydroxide (CH), MTA, and MTA with platelet-rich plasma (MTA + PRP) was performed on maxillary first molars of 8-week-old male Wistar rats (n = 36). After 3, 7, or 14 days, the teeth were analyzed for mineral density (MD) and volume of MD (VMD) via micro-focusing computed tomography (µCT), nestin, dentin matrix acidic phosphoprotein 1 (DMP1) immunohistochemistry, and real-time PCR for DMP1 mRNA expression. MTA stimulated the early phase differentiation of the IPMSCs into odontoblasts, with positive results for nestin and DMP1 compared with CH. Moreover, MTA + PRP stimulated calcified granule and dentin bridge formation through calcium mineral deposition, following the induction of DMP1 mRNA expression in IPMSCs. Our results suggested that the combination of MTA and PRP is an effective and clinically applicable method for activating endogenous dental pulp stem cells into odontoblasts in the early stages of pulp regeneration