Early features of cellular ageing impair differentiation capacity in human lymph node fibroblasts prior to rheumatoid arthritis onset

Objective Cellular ageing of the immune system has been suggested to play a role in the pathogenesis of rheumatoid arthritis (RA). RA onset is preceded by a preclinical phase of systemic autoimmunity without overt tissue inflammation, allowing the investigation of predisease cellular dysfunction in at-risk individuals. Lymph nodes (LNs) are crucial for (auto)antibody development, with LN fibroblasts playing a key role in regulating immune homeostasis. Here, we investigated age-associated alterations in LN fibroblast differentiation capacity during the at-risk and established stages of RA. Methods Primary LN fibroblasts were isolated from inguinal LN core biopsies obtained from healthy controls, at-risk individuals and patients with RA. Adipogenic differentiation assays served as a functional readout of cellular plasticity and bulk RNA sequencing was used to evaluate ageing-related transcriptional changes. Results LN fibroblasts from at-risk individuals and patients with RA exhibited reduced adipogenic capacity, reflected by fewer lipid droplet-positive cells on differentiation. Transcriptomic analysis revealed downregulation of cell cycle, DNA repair and differentiation pathways. These fibroblasts also failed to upregulate the cell cycle switch G0S2 on stimulation. Conclusion Together, these findings indicate a disrupted coordination between cell cycle processes and differentiation in at-risk and RA LN fibroblasts, consistent with features of cellular ageing. Notably, these alterations were already present in at-risk individuals prior to clinical disease onset, suggesting that reduced fibroblast fitness may contribute to impaired LN tissue homeostasis in disease-prone individuals.