TLR9 and systemic lupus erythematosus: In SLE, TLR2, TLR4, TLR7, TLR9 and NOD2 are activated [152,153,154,155], leading to synergisms between TLR2-TLR4, TLR2-NOD2, TLR4-TLR7, TLR4-TLR9 and TLR4-NOD2.