Noor, Nur Azira Mohd
(2020)
Immunophenotypic profiles of monocytic microparticles derived from human blood monocytes and their potential role in coagulation and endothelial cell activation.
Masters thesis, Universiti Sains Malaysia.
Abstract
Monocytic microparticles (mMP) are small heterogeneous microvesicles
derived from monocytes following cellular activation or apoptosis. Significant
elevation of circulating mMP in various diseases increases its potential as a biomarker.
However, the phenotypic and functional role of mMP derived from human blood
monocytes is unknown. This study intended to characterise mMP derived from whole
monocytes, CD14+ monocytes, and CD16+ monocytes by assessing surface antigen
expressions and identify their role in coagulation and endothelial cell function. All
monocyte subtypes were cultured in the presence of lipopolysaccharides (LPS) for 18
hours. Monocytic MP were purified from culture supernatants by ultracentrifugation
before being analysed using flow cytometry. Meanwhile, prothrombin time (PT) assay
was performed to assess the coagulation potential of mMP. To assess the role mMP in
endothelial cells function, mMP were co-cultured with human umbilical vein
endothelial cells (HUVEC). The expression level of ICAM-1 and VCAM-1 on
HUVEC as well as the release of endothelial MP (eMP) upon mMP-HUVEC coculture
were then determined by using real time PCR and flow cytometry respectively.
This study has shown that CD14 and CD16 were expressed on all monocyte subtypesderived
mMP similar to their origin cells. Additionally, CD142 were expressed on
mMP and coagulation time was shortened in the presence of LPS-stimulated whole
monocyte-derived mMP. Meanwhile, the expression of intercellular adhesion
molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) were
increased in the presence of mMP derived from whole monocytes and mMP increased
the level of endothelial microparticles (eMP). These findings suggest that Annexin-V
in combination with CD14 and CD16 could be possible surface markers for mMP
phenotyping. Furthermore, mMP may possess procoagulant properties as CD142 on
their surface may be the major player in coagulation and they were able to activate
endothelial cells, suggesting a potential role in endothelial cell function.
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