MiR-204/-211 double knockout exacerbates rheumatoid arthritis progression by promoting splenic inflammation

•MiR-204/-211 and SSRP1 was observed in the spleens of CIA mice compared to wt mouse spleens. Immunized dKO mice exhibited a higher incidence of CIA onset and a more exacerbated RA disease phenotype, characterized by increased spleen inflammation score and elevated levels of IL-1β, TNF-α, and SSRP1 expression.•AAV-shSSRP1 injection in CIA dKO mice significantly reduced spleen inflammation scores, IL-1β and TNF-α expression levels, and down-regulated Ki-67 expression compared to CIA dKO mice.•These results showed that knockout of miR-204/-211 exacerbated the onset of CIA, while miR-204/-211 played a protective role against the progression of splenic inflammatory and proliferative progression in RA by targeting SSRP1. Collagen-induced arthritis (CIA) model was induced in C57BL/6 wild-type (wt) and C57BL/6 miR-204/-211 double-knockout (dKO) mice to investigate the role of miR-204/-211 in suppressing splenic inflammation in rheumatoid arthritis (RA). Differences of miR-204/-211 and structure-specific recognition protein 1 (SSRP1) in the spleen of DBA/1J wt and CIA mice were detected via PCR and immunohistochemistry. CIA was induced in both C57BL/6 wt and C57BL/6 miR-204/-211 dKO mice, and the onset of CIA and disease severity were statistically analyzed. Immunohistochemistry staining of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and SSRP1 in spleen or knee joints was performed and analyzed. In CIA miR-204/-211 dKO mice, AAV-shSSRP1 was intra-articularly injected, with both the AAV-shRNA Ctrl and AAV-shRNA Ctrl CIA groups receiving the same dose of AAV-shRNA. Spleen sections were stained with hematoxylin and eosin (H&E). Compared to wt mouse spleens, aberrant expression of miR-204/-211 and SSRP1 was observed in the spleens of CIA mice. Immunized dKO mice exhibited a higher incidence of CIA onset and a more exacerbated RA disease phenotype, characterized by increased spleen inflammation score and elevated levels of IL-1β, TNF-α, and SSRP1 expression. AAV-shSSRP1 injection in CIA dKO mice significantly reduced spleen inflammation scores, IL-1β and TNF-α expression levels, and down-regulated Ki-67 expression compared to CIA dKO mice. Knockout of miR-204/-211 exacerbated the onset of CIA in C57BL/6 mice, while miR-204/-211 played a protective role against the progression of splenic inflammatory and proliferative progression in RA by targeting SSRP1.