Patients with higher inflammation state defined by serum CRP levels exhibited enrichment of sublining/intermediate fibroblast and endothelial cell (venules and arteriolar endothelium) populations relative to total synovial cells, indicating a potential critical role for these cells in potentiating inflammation in JIA synovium (Fig. 1l-m), as sublining fibroblasts are known as a resource of inflammatory molecules in RA-synovium(28, 32). Here, CRP is linked to rheumatoid arthritis.