AHR and rheumatoid arthritis: GSEA indicated a tendency to reduced AHR pathway signalling in RA macrophages (FDR = 0.1; GSE49604; Fig. 5e); the AHR gene set enrichment in OA cells was statistically significant when gene expression profiles for BMDC from RA and OA patients were analysed (FDR ≤0.25; Fig. 5f).