CD19 + CD21lo/neg cells are increased in systemic sclerosis-associated interstitial lung disease

Erin M Wilfong,Elise Rizzi,Rosemarie B Dudenhofer,Leslie J Crofford,Kaitlyn E Bunn,Narender Annapureddy,Rachel H Bonami,April Barnado,Joyce E Johnson,Katherine N Vowell,Peggy L Kendall

doi:10.1007/s10238-021-00745-5

Abstract

Interstitial lung disease (ILD) represents a significant cause of morbidity and mortality in systemic sclerosis (SSc). The purpose of this study was to examine recirculating lymphocytes from SSc patients for potential biomarkers of interstitial lung disease (ILD). Peripheral blood mononuclear cells (PBMCs) were isolated from patients with SSc and healthy controls enrolled in the Vanderbilt University Myositis and Scleroderma Treatment Initiative Center cohort between 9/2017–6/2019. Clinical phenotyping was performed by chart abstraction. Immunophenotyping was performed using both mass cytometry and fluorescence cytometry combined with t-distributed stochastic neighbor embedding analysis and traditional biaxial gating. This study included 34 patients with SSc-ILD, 14 patients without SSc-ILD, and 25 healthy controls. CD21lo/neg cells are significantly increased in SSc-ILD but not in SSc without ILD (15.4 ± 13.3% vs. 5.8 ± 0.9%, p = 0.002) or healthy controls (5.0 ± 0.5%, p < 0.0001). While CD21lo/neg B cells can be identified from a single biaxial gate, tSNE analysis reveals that the biaxial gate is comprised of multiple distinct subsets, all of which are increased in SSc-ILD. CD21lo/neg cells in both healthy controls and SSc-ILD are predominantly tBET positive and do not have intracellular CD21. Immunohistochemistry staining demonstrated that CD21lo/neg B cells diffusely infiltrate the lung parenchyma of an SSc-ILD patient. Additional work is needed to validate this biomarker in larger cohorts and longitudinal studies and to understand the role of these cells in SSc-ILD.

Highlights

It is plausible that a B cell subset might drive SSc-Interstitial lung disease (ILD) given the known infiltration of B cells in SSc-ILD [22] and open-label trials of rituximab in SSc-ILD [23, 24].The purpose of this study was to investigate if a B cell population might serve as a cellular biomarker for SSc-ILD using a combination of targeted gating of known autoimmune-prone subsets [25,26,27,28] and minimally supervised analyses using mass cytometry by time-of-flight (CyTOF).Systemic sclerosis (SSc) is a rare autoimmune condition afflicting between 7 and 489 per million people worldwide [1]
The primary results of these investigations can be summarized as follows: (1) C D21lo/neg B cells are significantly increased in SSc-ILD but not SSc without ILD, (2) The CD21lo/neg biaxial gate comprises several different cell subsets, all of which are increased in SSc-ILD, (3) The majority of CD21lo/neg B cells are tBET positive, and (4) CD21lo/neg B cells may infiltrate the lung parenchyma in SSc-ILD
In addition to the novel findings we report, our results recapitulate previous B cell abnormalities observed in SSc

Summary

Introduction

It is plausible that a B cell subset might drive SSc-ILD given the known infiltration of B cells in SSc-ILD [22] and open-label trials of rituximab in SSc-ILD [23, 24].The purpose of this study was to investigate if a B cell population might serve as a cellular biomarker for SSc-ILD using a combination of targeted gating of known autoimmune-prone subsets [25,26,27,28] and minimally supervised analyses using mass cytometry by time-of-flight (CyTOF).Systemic sclerosis (SSc) is a rare autoimmune condition afflicting between 7 and 489 per million people worldwide [1]. The purpose of this study was to investigate if a B cell population might serve as a cellular biomarker for SSc-ILD using a combination of targeted gating of known autoimmune-prone subsets [25,26,27,28] and minimally supervised analyses using mass cytometry by time-of-flight (CyTOF). Interstitial lung disease (ILD), a major cause of morbidity and mortality, is seen in 15–38% of SSc patients [2,3,4,5] with a higher burden of lung involvement among African Americans patients [6]. ILD is a significant cause of morbidity, and dyspnea significantly affects health-related quality of life measures independent of overall disease severity [9, 10]

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