The immunoregulatory function of peripheral blood CD71+ erythroid cells in systemic-onset juvenile idiopathic arthritis.

CD71+ erythroid cells (CECs) are recognized to have an immunoregulatory function via direct cell-cell interaction and soluble mediators. Circulating CECs appear in newborns or patients with hemolytic and cardiopulmonary disorders. To assess the biological role of CECs in systemic inflammation, we studied the gene expression and function in systemic-onset juvenile idiopathic arthritis (SoJIA). Peripheral blood mononuclear cells of SoJIA patients expressed upregulated erythropoiesis-related genes. It represented the largest expansion of CECs during active phase SoJIA among other inflammatory diseases. Despite the opposing roles of erythropoietin and hepcidin in erythropoiesis, both serum levels were in concert with the amounts of SoJIA-driven CECs. Circulating CECs counts in inflammatory diseases were positively correlated with the levels of C-reactive protein, IL-6, IL-18, or soluble TNF receptors. Co-culture with active SoJIA-driven CECs suppressed secretions of IL-1ß, IL-6, and IL-8 from healthy donor monocytes. The top upregulated gene in SoJIA-driven CECs was ARG2 compared with CECs from cord blood controls, although cytokine production from monocytes was suppressed by co-culture, even with an arginase inhibitor. CECs are driven to the periphery during the acute phase of SoJIA at higher levels than other inflammatory diseases. Circulating CECs may control excessive inflammation via the immunoregulatory pathways, partly involving arginase-2.

A non-invasive diagnosis of histiocytic necrotizing lymphadenitis by means of gene expression profile analysis of peripheral blood mononuclear cells.

Histiocytic necrotizing lymphadenitis (HNL), also called Kikuchi-Fujimoto disease, is a benign, self-limiting inflammatory disease with fever and painful cervical lymphadenopathy of unknown etiology. A lymph node biopsy is required for the definitive diagnosis because of no specific symptoms or laboratory findings for HNL. To establish the rapid non-invasive diagnostic method for this disease, we investigated genes specifically expressed in the patients by analyzing whole transcriptome using microarray analysis of peripheral blood mononuclear cells (PBMC). The top five up-regulated genes (IFI44L, CXCL10, GBP1, EPSTI1 and IFI27) in HNL were interferon-induced genes (ISGs). The expression levels of the up-regulated genes by microarray were verified by quantitative PCR. High levels of serum CXCL10 concentration were confirmed at the symptomatic phase of HNL patients. The expression levels of these 5 genes positively correlated with each other (r(2) = 0.28-0.60). The genes were also highly expressed in HNL lymph nodes. The discriminant analysis using the expression levels of these five genes distinguished HNL with 84% accuracy. The combination of up-regulated ISGs in HNL seemed to be a specific response induced by viral infections or autoantigens. An analysis of the gene expression profile of PBMC may provide a rapid non-invasive diagnosis of HNL.

Cardiac side population cells have a potential to migrate and differentiate into cardiomyocytes in vitro and in vivo.

Side population (SP) cells, which can be identified by their ability to exclude Hoechst 33342 dye, are one of the candidates for somatic stem cells. Although bone marrow SP cells are known to be long-term repopulating hematopoietic stem cells, there is little information about the characteristics of cardiac SP cells (CSPs). When cultured CSPs from neonatal rat hearts were treated with oxytocin or trichostatin A, some CSPs expressed cardiac-specific genes and proteins and showed spontaneous beating. When green fluorescent protein-positive CSPs were intravenously infused into adult rats, many more ( approximately 12-fold) CSPs were migrated and homed in injured heart than in normal heart. CSPs in injured heart differentiated into cardiomyocytes, endothelial cells, or smooth muscle cells (4.4%, 6.7%, and 29% of total CSP-derived cells, respectively). These results suggest that CSPs are intrinsic cardiac stem cells and involved in the regeneration of diseased hearts.