CD4+ tissue-resident memory Th17 cells are a major source of IL-17A in Spondyloarthritis synovial tissue
Feng Liu, Hui Shi, Jason D. Turner, Rachel Anscombe, Jiaqi Li, Takuya Sekine, Ariane Hammitzsch, Devika Agarwal, Christopher B. Mahony, Jiewei Chen, Benjamin Kendrick, Dajiang Du, Qiang Tong, Lihua Duan, Kyla Dooley, Hai Fang, Ilya Korsunsky, Roopa Madhu, Adam P. Cribbs, Matthias Friedrich, Brian D. Marsden, Yi‐Ling Chen, Graham S. Ogg, Anna Adams, Warner Chen, Steven Leonardo, Fiona E. McCann, Christopher D. Buckley, Terence Rooney, Thomas Freeman, Holm H. Uhlig, Calliope A. Dendrou, Adam P. Croft, Andrew Filer, Paul Bowness, Liye Chen
Abstract
OBJECTIVES: Interleukin (IL)-17A is a key driver of spondyloarthritis (SpA) joint pathology. We aimed to identify its cellular source in synovial tissue from patients with 2 forms of SpA, namely axial SpA (AxSpA) and psoriatic arthritis (PsA). METHODS: Synovial tissue from patients with SpA was profiled using single-cell RNA sequencing (scRNA-seq; AxSpA, n = 5; PsA, n = 6) or spatial RNA profiling (PsA, n = 4). CellPhoneDB was used to infer cell-cell communication. Tissue-resident memory Th17 (TRM17)-like cells were generated in vitro using blood memory CD4+ T cells from SpA patients. An epigenetic inhibitor library, siRNA, and clustered regularly interspaced short palindromic repeats (CRISPR) were used to identify epigenetic regulator(s) for TRM17. RESULTS: scRNA-seq showed that CD4+CXCR6+ TRM17 cells are the predominant spontaneous IL17A producers in SpA synovium. Cell-cell communication and single-cell spatial analysis support the interaction between TRM17 and CLEC10A+ dendritic cells, which were activated in SpA. Both sublining and lining fibroblasts in SpA synovium showed evidence of interleukin (IL)-17A activation. In vitro-generated CD4+ TRM17-like cells phenocopied joint tissue TRM17, producing IL-17A/F upon T cell-receptor (TCR) stimulation, which was further enhanced by cytokines. Perturbation of BRD1 inhibited the generation of TRM17-like cells. CONCLUSIONS: CD4+ TRM17 cells are the predominant source of IL-17A in SpA synovial tissue. TCR stimulation is essential for the secretion of IL-17A by CD4+TRM17-like cells. The epigenetic regulator bromodomain-containing protein 1 (BRD1) contributes to the generation of CD4+TRM17. Depleting CD4+TRM17 cells in SpA is thus a therapeutic strategy with potential to induce long-term remission.