Single Cell Transcriptomic Analysis of Popliteal Lymph Nodes from TNF-Tg Mice with Early and Advanced Inflammatory-Erosive Arthritis

Immune cell dynamics in lymph nodes downstream of inflamed joints are associated with inflammatory-erosive arthritis in both tumor necrosis factor transgenic (TNF-Tg) mice and rheumatoid arthritis (RA) patients. In TNF-Tg mice, "Early" stages of arthritis are related to dramatic PLN "Expansion" with increases in joint-draining popliteal lymph node (PLN) volume and fluid flow, while CD21-high / CD23+ B-cells in inflamed nodes (Bin cells) accumulate in the PLN follicles. Onset of "Advanced" inflammatory-erosive arthritis is related to a PLN "Collapse" where fluid flow is reduced as Bin cells translocate from the PLN follicles into the sinuses and are thought to mechanically inhibit lymphatic drainage. Through single-cell RNA-sequencing, we aimed to evaluate changes in PLN immune cell populations during Early and Advanced arthritis to determine mechanisms mediating the Bin cell translocation and the relationship with arthritic progession in the afferent joints. Overall design: Two total single-cell RNA-seq samples are provided (n=3 mice, 6 PLNs pooled per sample); both samples are from TNF-Tg male mice, one with Early arthritis (5-6 months of age) and one with Advanced arthritis (>8 months of age). TNF-Tg females exhibit early mortality related to cardiopulmonary disease, and thus male mice are utilized to investigate these chronic lymphatic processes. The TNF-Tg mice are on a C57BL/6 genetic background.