ABSTRACT
The physio-pathological relevance of the one-carbon metabolism (OCM) is illustrated by the chemotherapeutic and anti-inflammatory effects of the antifolates Pemetrexed (PMX) and Methotrexate (MTX) in cancer and rheumatoid arthritis (RA). We report that OCM determines the functional and gene expression profile of human macrophages. PMX induces the acquisition of a p53-dependent proinflammatory gene signature in human monocyte-derived macrophages (GM-MØ). Indeed, OCM blockade reprograms GM-MØ towards a state of LPS-tolerance at the signaling and functional levels, an effect abolished by folinic acid. Importantly, OCM blockade led to reduced expression of membrane-bound and soluble CD14 (sCD14), whose exogenous addition restores LPS sensitivity. The therapeutic relevance of these results was confirmed in early RA patients, as MTX-responder RA patients exhibit lower sCD14 serum levels, with baseline sCD14 levels predicting MTX response. Our results indicate that OCM is a metabolic circuit that critically mediates the acquisition of innate immune tolerance, and positions sCD14 as a valuable tool to predict MTX-response in RA patients.
Competing Interest Statement
IG-A reports personal fees from Lilly and Sanofi; personal fees and non-financial support from BMS; personal fees and non-financial support from Abbvie; research support, personal fees and non-financial support from Roche Laboratories; non-financial support from MSD, Pfizer and Novartis, not related to the submitted work. The rest of the authors declare no commercial or financial conflict of interest.