PPARA and rheumatoid arthritis: In the KEGG analysis, processes such as “Cytokine-cytokine receptor interaction”, “Rheumatoid arthritis”, “Toll-like receptor signaling pathway” and “Type I diabetes mellitus” were upregulated, while “PPAR signaling pathway”, “Tyrosine metabolism” and “Insulin signaling pathway” were downregulated (Figures 4C, D).