Immunophenotyping of Patients With Rheumatoid Arthritis Reveals Difference in CD27+IgD+ Unswitched Memory B Cell Profiles

Abstract

Objectives: Over the past decades, the prevalence of noncommunicable diseases has surged significantly, including the systemic autoimmune disorder rheumatoid arthritis (RA). Despite extensive research and advancement of RA therapy, effective prevention strategies or cures remain elusive, and the mechanisms underlying RA pathogenesis unclear. It is crucial to gain deeper insights into RA pathophysiology. The objective of this study is to provide a comprehensive immunophenotyping of patients with RA. Methods: We generated and analyzed deep immunophenotyping data from 52 patients with RA and 47 healthy controls (HCs). Whole blood samples were stained with extracellular markers, and intracellular antibodies and analyzed for 32 different cell markers using mass cytometry by time of flight. The acquired data was analyzed by both manual and automatic unsupervised tools and subsequently complemented with anthropometric data and clinical-laboratory parameters. Results: We observed a significant disparity in immune cell profiles between patients with RA and HC, notably a reduced frequency of CD27⁺IgD⁺ unswitched memory B (_mB) cells in patients with RA (p-value < 0.01), with the disease RA being the primary and only significant factor explaining up to 17.9% of the variance of these cells. Conclusion: Our results reveal, for the first time, that a reduced frequency of unswitched _mB cells in patients with RA is the only significant abnormality distinguishing patients with RA from HC in a complex immunophenotyping panel of 72 different cell populations. This provides important information to further individualize various interventions and possibly help to design novel therapeutic interventions.

Keywords: CyTOF; IgD+CD27+ unswitched memory b cells; autoimmunity; immunology; immunophenotyping; rheumatoid arthritis.

Figure 1

Representative CD27 IgD dot plots from a healthy control (HC) and a patient with rheumatoid arthritis (RA) indicating the distribution and percentages of the following memory B cell subsets in the total CD45⁺ cell population: CD27⁺IgD⁺ (unswitched); CD27⁺IgD⁻ (switched); CD27⁻IgD⁺ (naïve); CD27⁻IgD⁻ (double negative).

Figure 2

Differences in cell expression in unswitched memory B (_mB) cells in patients with rheumatoid arthritis (RA) compared to healthy controls (HCs). The left plot illustrates the frequency of unswitched _mB cells as a proportion of the overall population of CD45⁺ cells, whereas the right plot depicts the frequency of unswitched _mB cells relative to the total B cell population.

Figure 3

Impact of different factors on unswitched memory B (_mB) cell frequency in patients with rheumatoid arthritis (RA) and healthy controls (HCs). RA is the primary and only significant factor explaining up to 17.9% of the variance of unswitched mB cells in this model. WHR, waist–hip ratio; Walk, medium and walk, low; a medium and low frequency of walking for longer than 10 min; sleep, hours of sleep; Creatinine, creatinine levels µmol/L.

Figure 4

Impact of different treatments on cell expression in unswitched memory B (_mB) cells in patients with rheumatoid arthritis (RA) compared to healthy controls (HCs). The left plot illustrates the frequency of unswitched _mB cells as a proportion of the total B cell population, whereas the right plot depicts the frequency of unswitched _mB cells relative to the overall population of CD45⁺ cells, based on the hierarchical analysis. The patients were separated into four groups, based on their different treatments. No significant differences between the treatment groups were observed.