P085 Deep profiling of the circulating immune cell landscape in inflammatory bowel disease by mass cytometry

• Published in: Journal of Crohn's and colitis 2020-01, Vol.14 (Supplement_1), p.S177-S177
• Main Authors: Horn, V, Borek, Z, Mantzivi, E, Urbicht, M, Boesel, D, Baumgart, S, Sonnenberg, E, Lissner, D, Siegmund, B, Mei, H, Hegazy, A N
• Format: Article
• Language: English
• ISSN: 1873-9946; 1876-4479
• DOI: 10.1093/ecco-jcc/jjz203.214

Abstract Background A complex interplay of innate and adaptive immune cells maintains intestinal homeostasis. In inflammatory bowel disease (IBD), the fragile balance between regulatory and inflammatory cell subsets breaks down. The latter are recruited to the gut where they sustain intestinal inflammation and lead to tissue destruction. Due to re-circulation and gut-homing processes, the circulating immune cell compartment experiences profound changes that reflect disease activity. Meanwhile, single-cell techniques like mass cytometry have become a powerful technology to shed a light on the heterogeneity and dynamics of immune cells. As obtaining intestinal biopsies from inflamed gut is invasive and poses patients at risk, diagnostics and therapy monitoring from ‘liquid biopsies’ would be a great advance. A deeper understanding of the circulating immune cell landscape in IBD pre- and post-treatment could significantly contribute to IBD patient management by early prediction of therapy response. Methods Whole blood from 24 IBD patients—including 16 ulcerative colitis (UC) and 6 Crohn’s disease (CD) patients before treatment—and 18 age- and sex-matched healthy donors (HDs) was incubated with proteomic stabiliser and frozen. Upon thawing, cell suspensions were Palladium barcoded, stained with a 37-marker panel and acquired on a Helios mass cytometer. The generated dataset was normalised, de-barcoded and subsequently analysed. Results Using dimensionality reduction and neural-network-based algorithms, we faithfully identified different circulating immune subsets in healthy donors and IBD patients. Our preliminary analysis revealed altered myeloid cell populations, like neutrophils and macrophages, in IBD patients. In line with an activation of the innate immune system, we observed a considerable increase in the neutrophil compartment compared with healthy donors. Moreover, patterns of marker expression within different subsets showed substantial differences between healthy donors, CD and UC patients. Conclusion Here, we show a mass cytometry panel that identifies the circulating immune cell landscape and shows major differences between healthy donors, CD and UC patients.