Recent studies have associated osteopontin (OPN) with allergic inflammation; however, its role in human asthma remains unclear. The aim of this study was to measure OPN levels in the serum, bronchoalveolar lavage fluid (BALF) and bronchial tissue of healthy controls and asthmatics, identify cellular sources of OPN and examine possible correlations between OPN expression, disease severity and airway remodelling.Serum samples were obtained from 35 mild-to-moderate asthmatics, 19 severe asthmatics and 17 healthy controls in the steady state and in cases of exacerbation. Of these subjects, 29 asthmatics and nine controls underwent bronchoscopy with endobronchial biopsy and BALF collection. OPN expression was determined by ELISA and immunohistochemistry/immunofluorescence. Reticular basement membrane thickness and goblet cell hyperplasia were also determined.Serum and BALF OPN levels were significantly increased in all asthmatics in the steady state, whereas serum levels decreased during exacerbations. OPN was upregulated in the bronchial tissue of all patients, and expressed by epithelial, airway and vascular smooth muscle cells, myofibroblasts, T-lymphocytes and mast cells. OPN expression correlated with reticular basement membrane thickness and was more prominent in subepithelial inflammatory cells in severe compared to mild-to-moderate asthma.OPN expression is upregulated in human asthma and associated with remodelling changes, and its subepithelial expression correlates with disease severity.

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Increased Age-Related B-cells in Patients with Aplastic Anemia Introduction: Aplastic anemia is a rare disease characterized by immune dysregulation. T cells in aplastic anemia are characterized by various intrinsic defects leading to increased IFN-g levels and Fas-mediated apoptosis of hematopoietic stem cells. We and others, have previously shown that the transcription factor T-bet is over-expressed in T cells from patients with aplastic anemia. Recently it was shown that a subpopulation of B cells also express T-bet; these cells are characterized as age-related B cells (ABCs) and express high levels of CD11c and CD19, they are CD21 negative and express T-bet. These T-bet+ ABCs are found increased in patients with autoimmune diseases (i.e. systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis). Stimulation of B cells with antigens, Toll-like receptors and IFN-g leads to the formation of ABCs, which in turn "talk" to the T cells and stimulate them. Stimulation of T cells leads to IFN-g production, and this IFN-g may lead to further induction of T-bet expressing B cells (ABCs). Specific aim: In this study we wanted to examine the expression of ABCs in patients with aplastic anemia. We isolated peripheral blood mononuclear cells (PBMCs) from patients with aplastic anemia (n=10) and eight healthy, age- matched controls. Written informed consent was obtained from all study subjects. Cells were stained with the surface markers CD11c, CD19 and CD21, and subsequently analyzed using flow cytometry. An anti-Tbet antibody was also used after cell permeabilization. The CD11c-high, CD19 positive, CD21 negative, T-bet positive population represent the ABCs. Results: Patients with aplastic anemia at presentation showed increased numbers of circulating ABCs compared to healthy controls (29,08±1,62% vs 4,06 ±0,4 % respectively, p<0.001).(Fig. 1). Patients who responded to treatment showed comparable levels of ABCs to those of healthy individuals (5,93±0,6% vs 4,06 ±0,4 % respectively). Non-responders had statistically significant increased levels of ABCs compared to healthy controls (p<0,001). Also, non-responders had ABCs levels similar to those of aplastic anemia patients at presentation (29,08±1,62% vs 31,7 ±2,97 % respectively, p=0,44). Conclusion: Although the number of patients analyzed is limited, our preliminary results suggest that aplastic anemia patients show expanded ABCs compared to age-matched control subjects, and these numbers are related to disease status. Further analysis of a larger pool of subjects is underway along with the examination of the specific transcription factor Bcl-6, that is implicated in T-bet expression in ABCs. These results will reveal the role of ABCs in the immune pathogenesis of aplastic anemia. Figure 1. Figure 1. Disclosures Kattamis: CELGENE: Consultancy, Honoraria; Vifor Pharma: Consultancy; Novartis: Consultancy, Honoraria; ApoPharma: Honoraria.