IL6 and rheumatoid arthritis: As shown in Figure 5, RA patients with the highest levels of TNF-α or IL-6 had higher proportions of Enterobacteriaceae and Klebsiella, but lower proportions of Bifidobacterium (Bifidobacterium adolescentis and Bifidobacterium longum) and Faecalibacterium (Faecalibacterium prausnitzii) than those with the lowest levels of TNF-α or IL-6.