Signalling of toll-like receptors. Handb Exp Pharmacol. 2008;21-50. [PMID: 18071653 DOI: 10.1007/978-3-540-72167-3_2]

Pycnogenol, an extract from French maritime pine, suppresses Toll-like receptor 4-mediated expression of adipose differentiation-related protein in macrophages

Adipose differentiation-related protein (ADRP) is highly expressed in macrophages and human atherosclerotic lesions. We demonstrated that Toll-like receptor (TLR) 4-mediated signals, which are involved in atherosclerosis formation, enhanced the expression of ADRP in macrophages. Lipopolysaccharide (LPS) enhanced the ADRP expression in RAW264.7 cells or peritoneal macrophages from wild-type mice, but not in macrophages from TLR4-deficient mice. Actinomycin D almost completely abolished the LPS effect, whereas cycloheximide decreased the expression at 12 h, indicating that the LPS-induced ADRP expression was stimulated at the transcriptional level and was also mediated by new protein synthesis. LPS enhanced the ADRP promoter activity, in part, by stimulating activator protein (AP)-1 binding to the Ets/AP-1 element. In addition, preceding the increase of the ADRP mRNA, LPS induced the expression of interleukin (IL)-6, IL-1alpha, and interferon-beta mRNAs, all of which stimulated the ADRP expression. Antibodies against these cytokines or inhibitors of c-Jun NH(2)-terminal kinase and nuclear factor (NF)-kappaB suppressed the ADRP mRNA level. Thus TLR4 signals stimulate the ADRP expression both in direct and indirect manners. Pycnogenol (PYC), an extract of French maritime pine, suppressed the expression of ADRP and the above-mentioned cytokines. PYC suppressed the ADRP promoter activity and enhancer activity of AP-1 and NF-kappaB, whereas it did not affect the LPS-induced DNA binding of these factors. In conclusion, TLR4-mediated signals stimulate the ADRP expression in macrophages while PYC antagonizes this process. PYC, a widely used dietary supplement, might be useful for prevention of atherosclerosis.

Expression and significance of interferon regulatory factor 3 of peripheral blood dendritic cells in HBV-infected patients

AIM: To elucidate the roles of interferon regulatory factor-3 (IRF3) of peripheral blood dendritic cells (DCs ) in immune response induced by hepatitis B virus (HBV) .

METHODS: Monocytes CD14⁺ were separated in 28 chronic HBV-infected patients (CH) group and 27 healthy volunteers group (control group) using magnetic activated cell sorting. Then, monocytes were placed on a culture medium of RPMI 1640, which were later induced into premature MoDC using hGM-CSF and hIL-4. We stimulated DCs with PolyI:C. The mRNA expressions of IRF3, TLR3 and IFN-β were detected using real time PCR, TLR3 expression was detected using flow cytometry and levels of IFN-β in supernatant were evaluated by ELISA.

RESULTS: In the control group, there was significant elevation of IRF3 and IFN-β level at 12 h following stimulation of PolyI:C compared with that at 0 h. Expression level of IRF3 rose and then declined gradually at 24h and 48 h (86.27% ± 14.74% vs 70.78% ± 11.16%, P < 0.05). In CH group, there was no significant up-regulation of TLR 3 at 0, 12, 24 h while a significant up-regulation was observed at 48 h (85.46% ± 6.87% vs 69.17% ± 20.43%, P < 0.05). The concentration of IFN-β had no significant changes at 0 h, 12 h, 24 h and 48 h in CH groups, while there was a significant higher up-regulation of IFN-β mRNA expression level at 0, 12, 24 h in the control group than in CH group (P < 0.05).

CONCLUSION: Chronic HBV-infected patients fail to activate IRF 3 following virus contraction and thereby are unable to secrete enough IFN-β to eradicate HBV virus, which may partly contribute to persistent infection of HBV.