TLR9 and systemic lupus erythematosus: Significant correlations between TLR9, TGF-β1, and PDGF-B were found both at the protein level and mRNA level in SLE patients and healthy controls, while no significant correlation was found between TLR9 and MCP-1, TLR9 and ISG15, or TLR9 and IFNα.