Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement

The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.


Anti-Inflammatory Effect of Alpha-2 Adrenergic Agonists On Endothelial Cells

Herrera-Garcia1,  Ada, Dominguez-Luis1,  María-Jesús, Diaz-Martin1,  Ana, Arce-Franco1,  Maria Teresa, Feria-Rodriguez Sr.2,  Manuel, Diaz-Gonzalez1,  Federico

Hospital Universitario de Canarias, Tenerife, Spain,
Faculty of Medicine, Tenerife, Spain

Purpose:

Two stress pathways, the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system regulate the immune response through the release of corticosteroids and norepinephrine, respectively. Norepinephrine recognizes adrenergic receptors (alpha and beta1) expressed in the surface of cells involved in the inflammatory response. Our group has observed that alpha 2 adrenergic agonists are able to modulate the inflammatory response in animal models of inflammation. However, the mechanism through which these compounds reduce the inflammatory response has not been clarified.

Objectives:

To study the potential anti-inflammatory effect of alpha2 adrenergic agonists in human neutrophils and endothelial cells.

Method:

Human neutrophils were isolated from peripheral blood of normal donors and incubated at 37°C for 20` in medium alone or in the presence of the alpha 2 agonists, xylazine or UK14.304 and/or the alpha2 antagonist, RX821002. Human umbilical venous endothelial cells (HUVEC) isolated from donors were activated with TNF- alpha (20ng/ml) for 6–12h in medium alone, in the presence of one of the alpha2 agonists and/or RX821002. The effect of xylazine and UK14.304 on the basal expression of VCAM-1, ICAM-1 in HUVEC, was assessed by flow cytometry analysis. The strength of endothelial intercellular junctions was analyzed by VE-Cadherin staining and confocal microscopy. Neutrophil migration capability through activated endothelium was assessed by transwell assay (5mm) where IL-8 was the chemotactic factor. Variation in the L-Selectin and CD11b expression in neutrophis activated with TNF-alpha (20ng/ml, 20min) in basal conditions, in presence and absence of Xilazine and UK14.304 were assessed by flow cytometry. Wilcoxon test (p<0.05) was used to evaluate the statistical significance.

Results:

Both alpha2 adrenergic agonists prevent the variations in L-selectin and CD11b basal expression in a doses-dependent manner in human neutrophils activated with TNF- alpha. In activated HUVEC, the presence of xylazine significantly reduced the up-regulation of ICAM-1 in a doses-dependent manner, with a maximum of 0.8 microM (p<0.01). The basal migration of human neutrophils through activated HUVEC was decreased up to 40±8% in presence of UK14.304. This effect was reverted by RX821002. The endothelial intercellular surface positive for VE-Cadherin staining was increased in a 50% by UK14.308 respect to the basal.

Conclusion:

The alpha2 adrenergic agonists are able to modulate the inflammatory response at endothelium level. These compounds cause a reduction in the neutrophil movement across the endothelial barrier. This finding supports the endothelium as a therapeutic target for developing new anti-inflammatory agents potentially useful for rheumatic diseases.

To cite this abstract, please use the following information:
Herrera-Garcia, Ada, Dominguez-Luis, María-Jesús, Diaz-Martin, Ana, Arce-Franco, Maria Teresa, Feria-Rodriguez Sr., Manuel, Diaz-Gonzalez, Federico; Anti-Inflammatory Effect of Alpha-2 Adrenergic Agonists On Endothelial Cells [abstract]. Arthritis Rheum 2009;60 Suppl 10 :1476
DOI: 10.1002/art.26550

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