Single-cell RNA transcriptomic and plasma Lipidomic reveal the potential mechanisms of a Methotrexate-based therapy against Rheumatoid Arthritis

Objective: To assess whether a Methotrexate-based therapy could achieve more clinical benefit, we arranged a Simon 2-Stage Phase 1 Trial. Single-cell RNA sequencing and lipidomic profiling were performed to reveal the potential mechanisms. Methods: Patients were enrolled in an open-label, Simon 2-stage, single-center, single-arm trial at Guangdong Provincial Hospital of Chinese Medicine. Main inclusion criteria were defined as follows: Aged 18 to 70, low to medium disease activity, fulfilled the RA classification criteria of EULAR/ACR 2010. Patients received the oral medication of MTX 10–15 mg weekly and natural product granules twice a day. Primary outcome was the American College of Rheumatology (ACR) 20% preliminary definition of improvement. Single-cell RNA sequencing(scRNA-seq) on peripheral blood mononuclear cells (PBMCs) was used to show the aberrant metabolism before and after the trial. Plasma lipidomic profiling quantified the lipid changes caused by this MTX-based therapy. Finally, post-hoc analysis on responders and non-responders were used for further analysis. Results: Between October 2020 and June 2022, 46 patients received treatment, while 42 finished follow-ups. 27 of 46 (58.70%) patients achieved ACR20, and significant changes were observed in several secondary outcomes. Comparative scRNA-seq analysis before and after the treatment revealed that lipidomic metabolism was broadly downregulated. Plasma lipidomic profiling reveals that 40 lipids were observed significantly changed. Post-hoc analysis showed the lipid changes were separately linked to clinical parameters in responders and non-responders. Conclusion: The study reveals that the combination therapy of HQT+MTX is effective and has a certain correlation with lipid metabolism, but more rigorous study design is still needed to confirm this speculation.