The role of the antifolate methotrexate in LPS response in human macrophages

Macrophage phenotypic and functional heterogeneity derives from tissue-specific transcriptional signatures shaped by the local microenvironment. M-CSF drives the generation of human monocyte-derived macrophages with a potent anti-inflammatory activity upon stimulation. One-carbon metabolism (OCM) is a complex network of biosynthetic pathways that includes de novo biosynthesis of purines and thymidylate, amino acid metabolism, and methylation reactions. We explored the molecular impact of blocking OCM with high-doses of the anti-folate methotrexate (MTX) on the gene expression profile in M-CSF-primed human monocyte derived macrophages during LPS activation. Overall design: mRNA profiles of human untreated or MTX treated monocyte-derived macrophages exposed to 10 ng/ml LPS for 3h. Monocytes were cultured for 7 days containing M-CSF (10 ng/ml) to generate M-CSF-polarized macrophages (M-MØ). M-CSF was added every two days. Methotrexate (MTX, 5 uM) was added once on monocytes inmediatly before the initation of the M-CSF differentiation process. On day 7, M-MØ and MTX-M-MØ were exposed to LPS (10 ng/ml) for 3h.