Figure 10. Schematic summary of TLR9 function and TGF-β1 mediated TLR9 expression in cultured human RPE cells A: TLR9 effects on gene expression under hypoxia. PAMPs or DAMPs activated TLR9 induces gene expression and activation of MYD88, IRF7, and NF-κB, leading to upregulation of the gene expression of inflammatory (COX2, IFNA) and matrix metalloproteinase MMP9. TLR9 seems to play a role in inflammatory processes. Additionally, TLR9 increases the TGF-β1 secretion in cultured RPE cells and thereby TLR9 could inhibit its own gene expression via negative feedback mechanism. B: Inhibition of TLR9 by TGF-β1 is mediated by activation via MMP9, binding to the specific receptor and activation of canonical signaling via Smad3 and non-canonical signaling via p38 MAPK, JNK, and PI3K pathways. TGF-β1 seems to mediate an anti-inflammatory effect by inhibiting TLR9. .