Zhang, Xiang; (2024) CD36 regulates macrophage and endothelial cell activation and multinucleate giant cell formation in Anti Neutrophil Cytoplasm Antibody vasculitis. Doctoral thesis (Ph.D), UCL (University College London).

Preview

Text Zhang_10199370_thesis.pdf Download (9MB) | Preview

Abstract

ANCA associated vasculitis (AAV) is characterised by monocyte/macrophage activation and small blood vessel damage leading to complications such as kidney failure. In some patients, macrophage activation leads to giant cell and granuloma formation, resulting in tissue damage. CD36 is a transmembrane glycoprotein that is expressed on the surface of various cells, such as macrophages and vascular endothelial cells. CD36 is a crucial factor in the modulation of inflammatory processes and immune reactions. However, the specific role of CD36 in AAV has remained incompletely elucidated; Therefore, I investigated CD36 and its downstream signalling pathways in macrophages, endothelial cells and multinucleated giant cell formation in AAV patients and age matched controls. CD36 expression was found to be increased in AAV kidney biopsies on macrophages. Additionally, CD36 expression on classical and intermediate monocytes was significantly increased in both PR3- and MPO-AAV patients compared to healthy controls, regardless of disease activity status. Increased levels of soluble CD36 (sCD36) were observed in the plasma of AAV patients, both in PR3-and MPO-ANCA subtypes, also in both remission and active disease. Cell surface CD36 and sCD36 were increased on cells and in supernatants from THP1-derived macrophages and Human Dermal Microvascular Endothelial Cells (HDMEC) stimulated by Palmitic acid (PA) or TNF-α respectively and was attenuated by CD36 knockdown. Stimulation of THP1-derived macrophages with PA also generated M1 polarised macrophages with significant macrophage migration inhibitory factor (MIF) production and increased expression of c-Myc. In addition, there was an increase in multinucleate giant cell (MNGC) formation. These findings were all attenuated by CD36 knockdown and MIF antagonism. Similarly, PA stimulation of vascular endothelial cells increased CD36 and vascular cell adhesion molecule-1 (VCAM-1) expression and promoted MIF production, both attenuated by CD36 knockdown. Co-culture of endothelial cells and macrophages with PA resulted in increased migration of macrophages towards the activated endothelial cells and increased macrophage activation, while these findings were inhibited by CD36 knockdown. Only a small proportion of our patients produced anti-CD36 antibodies and these did not interfere with PA-stimulated CD36-mediated signalling. While levels of free fatty acids were not elevated in AAV patients’ plasma, oxidised-LDL, another CD36 ligand was. These data suggest that CD36 and one of its ligands are abnormally expressed in AAV patients. Signalling through CD36 may potentially explain many of the features found in AAV and contribute to persistent immune activation in some patients. Targeting CD36 or its downstream effectors MIF and c-Myc may represent a novel therapeutic strategy to be tested in AAV.

Downloads since deposit

Loading...

53Downloads

Download activity - last month

Export as XMLCSVJSON

Loading...

Download activity - last 12 months

Export as XMLCSVJSON

Loading...

Downloads by country - last 12 months

Export as JSONCSVXML

Loading...

Archive Staff Only

View Item