Project description:Vasculitis is characterized by the inflammation of blood vessels. In patients with giant cell arteritis (GCA) large- to medium-sized vessels are affected. Single-cell RNA sequencing was performed on GCA patients and healthy controls (HC) to study the transcriptome of peripheral blood mononuclear cells of patients and controls.
Project description:To identify the key coding genes underlying the biomarkers and pathways associated with giant cell arteritis (GCA), we performed in situ spatial profiling of molecules involved in the temporal arteries of GCA patients and controls
Project description:BACKGROUND: Giant Cell Arteritis (GCA) causes severe inflammation of the aorta and its branches and is characterized by intense effector T cells infiltration. The roles that immune checkpoints play in pathogenesis of GCA are still unclear.Our aim was to study the immune checkpoints interplay in GCA. METHODS: First, we used VigiBase, the WHO international pharmacovigilance database, to evaluate the relationship between GCA occurrence and immune checkpoint inhibitors (ICI) treatments. We then further dissected the role of ICI in the pathogenesis of GCA, using immunohistochemistry, immunofluorescence, transcriptomics and flow cytometry on peripheral blood mononuclear cells (PBMCs) and aortic tissues of GCA patients and appropriated controls. RESULTS: Using VigiBase, we identified GCA as a significant immune related adverse event associated with anti-CTLA-4 (Cytotoxic T-lymphocyte-associated-protein-4) but not anti-PD-1/PD-L1 treatment. We further dissected a critical role for CTLA-4 pathway in GCA by identification of the dysregulation of CTLA-4-derived gene pathways and proteins in CD4+ T cells (and specifically Tregs) present in blood and aorta of GCA patients versus controls. While Tregs were less abundant and activated/suppressive in blood and aorta of GCA versus controls, they still specifically upregulated CTLA-4. Activated and proliferating CTLA-4+ Ki-67+ Tregs from GCA were more sensitive to anti-CTLA-4 (Ipilimumab)-mediated in vitro depletion versus controls. CONCLUSIONS: We highlighted the instrumental role of CTLA-4 immune checkpoint in GCA which provides a strong rationale for targeting this pathway.
