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Toll-like receptors (TLRs) play significant roles in recognizing the pathogen-associated molecular patterns that induce innate immunity, and subsequently, acquired immunity. In general, TLRs have two downstream signaling pathways, the myeloid differential factor 88 (MyD88)-dependent and toll-interleukin-1 receptor domain-containing adapter-inducing interferon-β (TRIF)-dependent pathways, which lead to the activation of nuclear factor-kappa B (NF-κB) and interferon regulatory factor 3 (IRF3). 1-[5-methoxy-2-(2-nitrovinyl)phenyl]pyrrolidine (MNP) has been previously synthesized in our laboratory. To evaluate the therapeutic potential of MNP, its effect on signal transduction via the TLR signaling pathways was examined. MNP was shown to inhibit the activation of NF-κB and IRF3 induced by TLR agonists, as well as to inhibit the expression of cyclooxygenase-2, inducible nitric oxide synthase, and interferon inducible protein-10. MNP also inhibited the activation of NF-κB and IRF3 induced by the overexpression of downstream signaling components of the MyD88- or TRIF-dependent signaling pathways. These results suggest that MNP can modulate MyD88- and TRIF-dependent signaling pathways of TLRs, leading to decreased inflammatory gene expression. [ABSTRACT FROM AUTHOR]

Toll-like receptors (TLRs) recognize distinct pathogen-associated molecular patterns and play a critical role in innate immune responses. TLR signaling pathways can be largely classified as either myeloid differential factor 88 (MyD88)- or toll-interleukin-1 receptor domain-containing adapter inducing interferon-β (TRIF)-dependent pathways. C ompound of Designation red 10 binding ( CDr10b ) was synthesized to investigate its role in neuroinflammatory diseases. This study was conducted to determine whether CDr10b can affect TLR signaling pathways. CDr10b suppressed NF-κB activation as well as COX-2 and iNOS expression induced by TLR3 or TLR4 agonists. CDr10b also suppressed the activation of interferon regulatory factor 3 (IRF3) and the expression of interferon inducible protein-10 (IP-10) induced by TLR3 or TLR4 agonists. These results indicate that CDr10b can modulate the TRIF-dependent pathway of TLRs and has the potential to become a new therapeutic drug for chronic inflammatory diseases. [ABSTRACT FROM AUTHOR]