Introduction: Low-dose methotrexate (MTX) is the first-line treatment for rheumatoid arthritis (RA), but 30% to 50% of patients show an inadequate clinical response. Currently, no biomarker assesses the response of RA patients to MTX. In one of our previous studies with RA patients, proteomic profiling in blood revealed overexpression of glycolysis pathway enzymes in the remission group compared to the active RA group. This subsequent study aimed to validate these findings in another cohort of patients.

 

Material and methods: Two RA patient groups were established based on their disease activity score (DAS 28) after 6 months of MTX treatment: DAS28 < 2.6, indicating remission, and DAS28 > 3.2, indicating clinically active RA. At that time, blood was collected for untargeted protein identification and quantification using high-resolution mass spectrometry coupled with liquid chromatography. Differences in protein expression between the two groups of patients were studied with Perseus and R software tools.



Results: In this study, 26 patients were considered in remission, while 43 patients exhibited clinically active RA after 6 months of MTX treatment. The analysis of differentially expressed blood proteins between these two groups revealed one of the two proteins identified in the previous study. Additionally, interconnected and RA-related proteins were highlighted, including Filamin A, Protein S100-A7, Myosin-9, Lamin A/C, and Fermitin family homolog 3.



Conclusion: We partially replicated the results of the first study, confirming the potential of a protein as a future marker of MTX efficacy. Additionally, this second study offers new perspectives in the search for such a biomarker.