AB0143 CHARACTERIZATION OF CELLULAR INFILTRATE IN TEMPORAL ARTERITIS USING IMAGING MASS CYTOMETRY IN GIANT CELL ARTERITIS

Abstract

BackgroundImaging mass cytometry (IMC) is a high-plex imaging technique that incorporates flow cytometry principles while preserving the histological and architectural components of the tissue sample. Characterizing the entire cellular component of temporal artery (TA) in patients with giant cell arteritis (GCA) may provide clues towards novel diagnostic and therapeutic approaches.ObjectivesWe aimed at a comprehensive summary of the immune cells and pathways involved GCA by using IMC approach.MethodsTA samples from biopsy-proven GCA patients (n=2) and controls (CTLs, n=2) were analyzed using IMC with a panel of 15 staining antibodies.ResultsEleven cell populations were identified in arterial wall from GCA patients including both immune (CD20+ B cells, CD8+ T cells, CD4+ T cells, FOXP3+ Tregs, CD66b+ granulocytes, CD11b+ myeloid cells, CD14+ monocytes, CD68+ macrophages) and non-immune (aSMA+ smooth muscle cells, CD31+ endothelial cells, Vimentin+ fibroblasts) cells (Figure 1). The 3 layers (intima, media and adventitia) of the arterial wall was enriched by all the immune cell subsets in GCA except for granulocytes and myeloid cells. CD8+, CD4+ and FOXP3+ regulatory T cells were significantly increased in any layer of the TA. The proportion of B cells was also enhanced in both intima and adventitia and displayed a high level of Ki67 expression.Figure 1.Unbiased clustering of cellular infiltrate in temporal arteritis using Imaging Mass Cytometry.Heatmap of different cell type markers expressed by the 11 cell populations identified in the arterial wall of GCA patients: CD20+ B cells, CD8+ T cells, CD4+ T cells, FOXP3+ Tregs, CD66b+ granulocytes, CD11b+ myeloid cells, CD14+ monocytes, CD68+ macrophages, Vimentin+ fibroblasts, aSMA+ smooth muscle cells and CD31+ endothelial cells. A population of unidentified cells is also represented (A). Donut chart representing the relative composition of immune cells in the arterial wall of GCA patients (B). tSNE dimensional plots of the different cell clusters identified in the arterial wall of CTL and GCA patients (C). Percent and Heatmap of immune cells identified in the arterial wall of each patient (D).GCA: giant cell arteritis, CTL: controls, Tregs: regulatory T cells.ConclusionOur study provides an exhaustive overview of the distinct cell lineages involved in GCA and supports IMC approach to further characterize the immune networks active in GCA.Disclosure of InterestsNone declared