Multi-omics Analysis Identifies IgG2b Class-Switching with ALCAM-CD6 Co-Stimulation in Lymph Nodes During Advanced Inflammatory-Erosive Arthritis

Abstract

Defective lymphatic drainage and B-cell translocation into joint-draining lymph node sinuses are pathogenic phenomena in patients with severe rheumatoid arthritis (RA). However, the molecular mechanisms underlying this lymphatic dysfunction remain poorly understood. Here, by utilizing spatial and single-cell transcriptomics in tumor necrosis factor transgenic (TNF-Tg) mice, we characterized functional genomic changes in popliteal lymph nodes (PLNs) of "Early" and "Advanced" RA to determine the mechanisms orchestrating B-cell differentiation. We first show that Ighg2b expression localized to Marco+ sinuses and negatively correlated with bone volumes in ipsilateral joints. We further reveal that Advanced PLNs exhibited a concomitant accumulation of iron-laden macrophages and T-cells. Mechanistically, crosstalk between ALCAM+ macrophages and CD6+ T-cells was identified as a co-stimulatory pathway promoting IgG2b class-switching. These findings were validated by immunohistochemistry, flow cytometry, ELISPOT, and clinical correlates. Collectively, we propose that ALCAM-CD6 co-stimulation activates T cells, initiating IgG2b class-switching and plasma cell differentiation in RA flare.

Multi-omics analysis identifies IgG2b class-switching with ALCAM-CD6 co-stimulation in joint-draining lymph nodes during advanced inflammatory-erosive arthritis

“…We would like to thank the faculty and staff of the Histology, Biochemistry, and Molecular Imaging core, the Biomechanics and Multimodal Tissue Imaging core, and the Genomics Research Center at the University of Rochester for their contributions to this work. Portions of this work previously appeared online in the form of a preprint article on the BioRxiv repository (68).…”