TLR7 and systemic lupus erythematosus: Interestingly, the challenges of TLR7 ligand R837 and TLR9 ligand CpG 2006S, but not IFN-α, could significantly decrease CD180 expression in human PBMCs (Figure S1), indicating that increased percentages of CD180-negative monocytes and DCs in SLE patients maybe a result of hyper-activation of TLR7 and TLR9 pathways.