Effect of hydroxyurea and nitric oxide donors in the expression and function of adhesion molecules in red blood cells of sickle cell disease

Author(s)

Sheley Gambero

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
• Defense date: 2006-07-28

Examining board members

Fernando Ferreira Costa; Vagner de Castro; Heloísa Helena de Araújo Ferreira

• Advisor: Fernando Ferreira Costa; Nicola Amanda Conran Zorzetto

Abstract

Sickle cell vaso-occlusion constitutes a complex process involving interactions between SS red blood cells (RBC), endothelial cells, leukocytes, platelets, coagula tive factors and plasma proteins. Propagation ofthe vaso-occlusive process in sickle cell anemia (SCA) is a complex process involving the adhesion of SS red cells and reticulocytes to the vascular endothelium. The effect of hydroxyurea therapy (HUT) on the adhesive properties of sickle red cells and the expression of adhesion molecule genes by erythroid cells of SCA individuals is not yet fully understood. The expressions of the CD36 gene and the VLA-4 integrin subunit genes, CD49d (a-subunit) and CD29 (J3-subunit), were compared in the reticulocytes of steady-state SCA patients and patients on HUT using Real-Time PCR Basal adhesion of red cells ftom these subjects was also compared using static adhesion assays, as was surface protein expression, using flow cytometry. Basal sickle red cell adhesion to fibronectin was significantly greater than that of normal cells (P<O.OI); in contrast, HUT significantly decreased (P<O.OI) red cell adhesion to levels similar to those of control cells and this decrease could not be justified solely by alterations in reticulocyte numbers in this population. Accordingly, flow cytometry demonstrated that HUT significantly decreased CD36 and CD49d surface expression (P<O.Ol) and, importantly, significant reductions in the expressions of the CD36, CD49d and CD29 genes were seen (P<O.O5) in the reticulocytes of SCA patients on HU. Taken together, data support the hypothesis that HUT reduces the adhesive properties of sickle cells and that this decrease appears to be mediated, at least in part, by a decrease in the gene and, consequently, surface protein expression of adhesion molecules such as VLA-4 and CD36 (AU)