Fig. 2: MAO-B and GABA are aberrantly expressed in RA.

a Representative confocal images of concentration-dependent changes in MAO-B and GABA in response to TNF-α in FLSs (n = 3 for each group; scale bar, 50 µm). b, c Quantification of MAO-B and GABA intensity in FLSs (one-way ANOVA, Tukey’s multiple comparisons test). d Western blot showing MAO-B in FLSs. e, f Schematic image of the DCFDA assay and quantification of H₂O₂ in naive and TNF-α-stimulated FLSs (two-tailed unpaired t test, n = 43 for each group). g Quantification of IL-6 expression in naive and TNF-α-stimulated FLSs. h Western blot showing activated autophagy markers in TNF-α-activated FLSs. i–k Metabolite quantification in control and TNF-α-stimulated FLSs (one-way ANOVA, Tukey’s multiple comparisons test). l Quantification of IFN-γ, IL-10, IL-13, IL-1β, IL-6, and TNF-α in the serum of normal, OA, and RA patients (one-way ANOVA with Tukey’s multiple comparisons test, n = 20, 16, and 16). m Quantification of IFN-γ, IL-10, IL-13, IL-1β, IL-6, and TNF-α in the synovial fluid of OA and RA patients (two-tailed unpaired t test, n = 16 for each group). n Quantification of IFN-γ, IL-10, IL-13, IL-1β, IL-6, and TNF-α in the joint tissue of OA and RA patients (two-tailed unpaired t test, n = 16 for each group). o Western blot showing activated autophagy markers in the joint samples of OA and RA patients p Representative confocal images showing synovial MAO-B and GABA in OA and RA samples (N = 3 for each group; scale bar, 20 µm). q, r Quantification of synovial MAO-B and GABA (two-tailed unpaired t test). s Representative Western blot showing MAO-B and GAPDH and the quantification of synovial MAO-B expression (two-tailed unpaired t test). Error bars in the graphs indicate the SEM. *P < 0.05; **P < 0.01; ***P < 0.001. Statistical details are provided in Supplementary Table 1.