Characterization of Phenotypes and Functional Activities of Leukocytes From Rheumatoid Arthritis Patients by Mass Cytometry

Adrien Leite Pereira,Nicolas Tchitchek,Roger Le Grand,Xavier Mariette,Ernesto Marcos Lopez,Audrey Paoletti,Gaetane Nocturne,Samuel Bitoun,Antonio Cosma

doi:10.3389/fimmu.2019.02384

Abstract

Background: Rheumatoid arthritis (RA) is the most common autoimmune rheumatic disease and leads to persistent chronic inflammation. The pathophysiology of the disease is complex, involving both adaptive and innate immunity. Among innate immune cells, neutrophils have been rarely studied due to their sensitivity to freezing and they are not being collected after Ficoll purification.Methods: We used mass cytometry to perform a multidimensional phenotypic characterization of immune cells from RA-treated patients, which included the simultaneous study of 33 intra- or extra-cellular markers expressed by leukocytes. We were able to focus our study on innate immune cells, especially neutrophils, due to a specific fixation method before freezing. In addition, blood samples were stimulated or not with various TLR agonists to evaluate whether RA-dependent chronic inflammation can lead to immune-cell exhaustion.Results: We show that RA induces the presence of CD11blow neutrophils (33.7 and 9.2% of neutrophils in RA and controls, respectively) associated with the duration of disease. This subpopulation additionally exhibited heterogeneous expression of CD16. We also characterized a CD11ahigh Granzyme Bhigh T-cell subpopulation possibly associated with disease activity. There was no difference in cytokine expression after the stimulation of immune cells by TLR agonists between RA and controls.Conclusion: Mass cytometry and our fixation method allowed us to identify two potential new blood subpopulations of neutrophils and T-cells, which could be involved in RA pathology. The phenotypes of these two potential new subpopulations need to be confirmed using other experimental approaches, and the exact role of these subpopulations is yet to be studied.

Highlights

Rheumatoid arthritis (RA) is the most common inflammatory autoimmune rheumatic disease, with a prevalence of 0.5–1% in the adult population [1]
It is clear that innate immunity plays a role in shaping adaptive immunity, and much attention has been recently given to the study of monocytes and macrophages in RA [4]
Previous and current treatment, as well as the presence of anti-cyclic citrullinated peptide antibodies, rheumatoid factor (RF), and/or joint erosion were collected for each RA-treated patient

Summary

Introduction

Rheumatoid arthritis (RA) is the most common inflammatory autoimmune rheumatic disease, with a prevalence of 0.5–1% in the adult population [1]. It is clear that innate immunity plays a role in shaping adaptive immunity, and much attention has been recently given to the study of monocytes and macrophages in RA [4]. Neutrophils are numerically the most predominant innate immune cells both in blood and synovium. They have been studied in vitro for their capacity to form extracellular trap formation (NETosis) [5], playing a central role in the exposition of citrullinated autoantigens [6]. Rheumatoid arthritis (RA) is the most common autoimmune rheumatic disease and leads to persistent chronic inflammation. Neutrophils have been rarely studied due to their sensitivity to freezing and they are not being collected after Ficoll purification

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Conclusion