TLR9 and systemic lupus erythematosus: By analyzing the levels of TLR9, TGF-β1, and PDGF-B in SLE patients with LN, significant correlations were found between the mRNA expressions of TGF-β1 and PDGF-B (p = 0.0092, r = 0.61; Fig. 7a), the mRNA expressions of TLR9 and TGF-β1 (p = 0.0003, r = 0.51; Fig. 7b), and the mRNA expressions of TLR9 and PDGF-B (p = 0.0052, r = 0.44; Fig. 7c).