〔Abstract〕 Objective To study the effects and potential mechanisms of the aquaporin 1(AQP1) inhibitor acetazolamide(AZ) on the proliferation, apoptosis, and inflammatory response of rheumatoid arthritis(RA) fibroblast-like synoviocytes(FLS). Methods TNF-α-induced RA-FLS was served as in vitro RA model. MTT assay, IF staining, and EdU incorporation assay were applied to study AZ′s effects on RA-FLS proliferation. Hoechst staining, flow cytometry analysis of Annexin V-FITC/PI-stained cells, and mitochondrial membrane potential detection experiments were used to detect cell apoptosis. ELISA and quantitative real-time PCR methods were used to measure pro-inflammatory cytokine production. Cell autophagy was evaluated using IF staining and mCherry-GFP-LC3B puncta assay. Western blot was performed to detect the levels of autophagy, apoptosis, and proliferation-related proteins. Moreover, the role of autophagy inhibition in AZ′s effects on RA-FLS was examined by co-treating with the autophagy activator rapamycin(RAPA) or the autophagy inhibitor 3-methyladenine(3-MA). Results AZ dose-dependently inhibited cell proliferation, promoted apoptosis, and reduced the production of pro-inflammatory cytokines in RA-FLS. Furthermore, AZ suppressed cytoprotective autophagy in these cells, as evidenced by decreased LC3B levels(P