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Rituximab Downregulates Gene Expression Associated with Cell Proliferation, Survival, and Proteolysis in the Peripheral Blood from Rheumatoid Arthritis Patients:A Link between High Baseline Autophagy-Related ULK1 Expression and Improved Pain Control
Objective: To clarify molecular mechanisms for the response to rituximab in a longitudinal study. Methods: Peripheral blood from 16 RA patients treated with rituximab for a single treatment course and 26 healthy controls, blood and knee articular cartilages from 18 patients with long-standing RA, and cartilages from 14 healthy subjects were examined. Clinical response was assessed using ESR, ACPA, CRP, RF, DAS28 levels, CD19+ B-cell counts, bone erosion, and joint space narrowing scores. Protein expression in PBMCs was quantified using ELISA. Gene expression was performed with quantitative real-time PCR. Results: A decrease (p < 0.05) in DAS28, ESR, and CRP values after rituximab treatment was associated with the downregulation of MTOR, p21, caspase 3, ULK1, TNFα, IL-1β, and cathepsin K gene expression in the peripheral blood to levels found in healthy subjects. MMP-9 expression remained significantly higher compared to controls although decreased (p < 0.05) versus baseline. A negative correlation between baseline ULK1 gene expression and the number of tender joints at the end of follow-up was observed. Conclusions: The response to rituximab was associated with decreased MTOR, p21, caspase 3, ULK1, TNFα, IL-1β, and cathepsin K gene expression compared to healthy subjects. Residual increased expression in MMP-9, IFNα, and COX2 might account for remaining inflammation and pain. High baseline ULK1 gene expression indicates a good response in respect to pain.
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