Interactions between platelets from sickle cell anemia patients and human umbilical vein endothelial cells

Author(s)

Renata Proença Ferreira

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
• Defense date: 2013-07-31

Examining board members

Nicola Amanda Conran Zorzetto; Margareth Castro Ozelo; Erich Vinicius De Paula; Sandra Fatima Menosi Gualandro; Maria Stella Figueiredo

• Advisor: Fernando Ferreira Costa; Nicola Amanda Conran Zorzetto

Abstract

Sickle cell anemia (SCA) is a disease caused by a point mutation (causing the exchange of glutamic acid for valine), which results in the synthesis of an abnormal hemoglobin, hemoglobin S (HbS). The principal cause of morbidity in patients with SCA is vaso-occlusion, which results from the abnormal adhesion of red blood cells and white cells to blood vessel walls, leading to decreases in blood flow. Platelets from SCA patients present an increase in their adhesive properties and, therefore, we have previously suggested that they may participate in the vaso-occlusive process. Our current data show that platelets from SCA patients are able to activate endothelial cells, in vitro, in co-culture assays using Human Umbilical Vein Endothelial Cells (HUVEC) that were co-incubated with platelets from SCA patients. The expression of intercellular adhesion molecule 1 (ICAM-1) and E-selectin was significantly increased on the surface of HUVEC cells after their co-incubation with platelets from SCA patients (SCA platelets). The activation of adhesion molecule expression observed depended on the physical contact between platelets and HUVEC cells, as transwell inserts were able to significantly inhibit the expression of ICAM-1 and E-selectin on HUVEC following their culture in the presence of SCA platelets. The co-incubation of SCA platelets with HUVEC cells also resulted in a higher production and release of inflammatory mediators (cytokines), such as interleukin 8 (IL-8) and interleukin 1 beta (IL-1?) in the supernatant of these co-cultures. Platelets from SCA patients have inflammatory properties, releasing more platelet factor 4 (PF4), a pro-aggregating chemokine, than platelets from healthy subjects. The increased expression of the adhesion molecules, integrin ?IIb?3 and P-selectin, on the surface of platelets from SCA patients, may also indicate an increased platelet activation, favoring their adhesion to the inflamed endothelium. Nuclear factor-?B (NF-?B) is an important nuclear transcription factor involved in the activation of genes, including endothelial adhesion molecules genes. We found an increased gene expression of NF?BIA (encoding the p50 subunit of NF-kB), in association with increased gene expression of ICAM1 (encodes ICAM-1) in HUVEC, following the co-culture of these cells with platelets from SCA patients. The presence of the BAY 11-7082 inhibitor (inhibits the NF-?B signaling pathway) decreased the expressions of the ICAM-1 and E-selectin adhesion molecules on the surface of HUVEC cells when co-incubated with platelets from SCA patients. Our data corroborate our hypothesis that platelets probably participate in the process of vaso-occlusion in sickle cell anemia, since they have the ability to activate endothelial cells (in vitro), in turn, making them more inflammatory and adhesive. As such, we suggest that platelets represent an important target for new therapeutic approaches in sickle cell anemia (AU)

• FAPESP's process: 09/54279-0 - Interactions between platelets from sickle cell anemia patients and human umbilical vein endothelial cells (HUVEC): in vitro evaluation of platelets adhesion and their effects on the endothelial activation
• Grantee: Renata Proenca Ferreira
• Support Opportunities: Scholarships in Brazil - Doctorate