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  • br Materials and methods br Results Among probes


    Materials and methods
    Results Among 17,061 probes, the Mitochondrial DNA Isolation Kit mg of 758 probes (4.4%) showed at least a 2-fold upregulation (230 probes) or downregulation (528 probes) at day 3 after VMH lesioning as compared with sham-VMH lesioning. Supplement Table 1 shows the upregulated (>2-fold) and the downregulated (>2-fold) metabolism-related, identified by DNA microarray analysis. The results revealed that VMH lesions regulated some genes that are involved in B cell function (upregulated genes 1 probe; downregulated genes 19 probes), T cell function (upregulated genes 2 probes; downregulated genes 6 probes), B and T cell function (downregulated genes 4 probes), NK cell function (downregulated genes 5 probes), cytokine function (downregulated genes 9 probes) and others (upregulated genes 5 probes; downregulated genes 38 probes). Regarding the results of real-time PCR, the gene expressions of RT1-Bb was upregulated and that of Spib was downregulated (<0.05; Fig. 1). The results revealed VMH lesions downregulated some genes that are involved in positive regulation of immune system process, positive regulation of immune response, immune response, leukocyte activation, activation of immune response, chemokine receptor binding, chemokine activity, lymphocyte activation, positive regulation of T cell activation, and positive regulation of leukocyte activation (Table 1). DAVID functional annotation analysis revealed that the molecular pathway enriched in downregulated genes families included that associated with B cell receptor signaling pathway, chemokine signaling pathway, primary immunodeficiency, cytokine–cytokine interaction, intestinal immune network for IgA production, systemic lupus erythematosus, T cell receptor signaling pathway, natural killer cell mediated cytotoxicity, NOD-like receptor signaling pathway, leukocyte trasendothelial migration, asthma, graft-versus-host disease, complement and coagulation cascades, antigen proceeding and presentation, Fc epsilon RI signaling pathway, allograft rejection, autoimmune thyroid disease, and Fc gamma R-mediated phagocytosis (Table 2), whereas the molecular pathways in upregulated genes families were not detected.
    Discussion It has been proposed that the communication between the brain and pancreatic islets is important in integration of islet function with energy homeostasis [12]. We previously reported that VMH lesions regulated genes that are involved in functions related to cellular growth and proliferation [7] and metabolisms in pancreatic islets [8]. In the present study, we used a DNA microarray technique for mRNA expression profiling of rat pancreatic islets to investigate pancreatic islet cellular responses to VMH lesions, and detected the fact that VMH lesions regulated genes that were involved in functions related to immune response genes in pancreas islets. In the present study, we used freshly-isolated islets for gene expression profiling. Islet isolation has been shown to alter the expression of multiple genes including those involved in inflammation, hypoxia, and stress [13]. However, functional cluster analysis of our microarray did not show enrichment of genes in these categories. In the present study, VMH lesions downregulated multiple immune signaling pathways in rat pancreatic islets. Previous studies reported the relationships between pancreatic islets and immune system. For example, type 1 diabetes is an autoimmune disease. It was proposed that insulitis, the pancreatic islet inflammation present in Type 1 diabetes, results from a “dialog” between immune cells homing into the islets and the target beta cells [14]. Beta cells contribute to this dialog by local release of cytokines and chemokines and by delivering immunogenic signals during the cell death process; this, together with signals generated by invading immune cells, contributes to trigger and amplify (or dampen) insulitis. Numerous studies in rodents and human subjects have been performed in order to elucidate the role of B and T cells, which determine the risk of development and progression of diabetes [15]. Moreover, cytokines are released from immune cells, which may be recruited to the islets in diabetes, but they can also be produced by islet endocrine cells in response to environmental factors, including enter viral infection [16]. It is not known why VMH lesions can downregulated multiple immune signaling pathways in rat pancreatic islets. Further investigations are needed to clarify this.