Journal: Iranian Journal of Pharmaceutical Research : IJPR
Article Title: Dual TYK2/JAK1 Inhibition by Brepocitinib Reprograms Synoviocyte Pathobiology: Mechanistic Insights Into Targeted Therapy for Rheumatoid Arthritis
doi: 10.5812/ijpr-166019
Figure Lengend Snippet: Effects of brepocitinib on MH7A cell viability and JAK-STAT pathway activation. A, cell viability of MH7A synoviocytes following treatment with brepocitinib at concentrations of 0.5 µM, 1 µM, and 5 µM for 24 hours. MTT assay was performed, and absorbance at 570 nm was normalized to DMSO control (0.1%). Data represent mean ± SD from three independent experiments. * P < 0.05 vs. vehicle. Although small statistical differences were detected at 1 µM and 5 µM, all brepocitinib-treated groups maintained viability above the predefined non-cytotoxic threshold (≥ 85% of vehicle). Therefore, these changes are considered not biologically relevant and confirm that brepocitinib is non-cytotoxic within the tested range. doxorubicin (1 µM) was used as a positive control and showed a marked reduction (~20%) in viability, validating assay responsiveness. B, brepocitinib suppresses phosphorylation of JAK-STAT pathway proteins in MH7A synoviocytes. MH7A cells were treated with brepocitinib at concentrations of 0.5 µM, 1 µM, and 5 µM for 24 hours. Western blot analysis was performed to assess the expression of phosphorylated and unphosphorylated forms of TYK2, JAK1, STAT1, and STAT3. GAPDH was used as a loading control. Protein lysates (30 µg per lane) were resolved by SDS-PAGE and probed with specific antibodies as indicated. Blots are representative of three independent experiments. Regression analysis confirmed a significant concentration-dependent reduction in p-JAK1 and p-STAT3 (R² > 0.90, P < 0.01). C, validation in primary RA-FLS (HFLS-RA). Cells were treated with brepocitinib (0.5, 1, 5 µM, 24 h) or tofacitinib (1 µM) and analyzed by Western blot for p-TYK2, TYK2, p-JAK1, JAK1, p-STAT1, STAT1, p-STAT3, and STAT3. GAPDH served as loading control. Results represent mean ± SD from three independent experiments. Low, medium, and high doses correspond to 0.5, 1, and 5 µM brepocitinib, respectively. Regression analysis also confirmed dose-dependent suppression of p-TYK2, p-JAK1, p-STAT1, and p-STAT3 in RA-FLS (R² > 0.88, P < 0.01). D, primary RA-FLS (HFLS-RA) were treated with brepocitinib (1 µM) for 0, 30, 60, 240 minutes, and 24 hours. Western blot analysis was performed for p-STAT1, STAT1, p-STAT3, and STAT3, with GAPDH serving as the loading control. Values represent mean ± SD from at least three independent experiments. Significance compared with control: * P < 0.05, *** P < 0.001. Two-way ANOVA demonstrated significant effects of treatment, time, and their interaction (P < 0.05). In all experiments, low, medium, and high doses correspond to 0.5 µM, 1 µM, and 5 µM brepocitinib, respectively.
Article Snippet: Primary RA fibroblast-like synoviocytes (RA-FLS; HFLS-RA, Cell Applications, Cat. No. 408RA-05a) were cultured according to the supplier’s instructions in Synoviocyte growth medium (Cell Applications, Cat. No. 415-500).
Techniques: Activation Assay, MTT Assay, Control, Positive Control, Phospho-proteomics, Western Blot, Expressing, SDS Page, Concentration Assay, Biomarker Discovery