SDC1 and rheumatoid arthritis: In line with these results, synovia of RA and OA patients with low HOTAIR expression were characterized by higher CD20 + B cell (Fig. 9e) and, in particular, CD138+ plasma cell infiltration (Fig. 9f) and a lymphoid histological pattern (Fig. 9g: RA synovial tissues and Supplementary Fig. S5: OA synovial tissues).