title: Rifampicin Inhibits the LPS-induced Expression of Toll-like Receptor 2 via the Suppression of NF-kappaB DNA-binding Activity in RAW 264.7 Cells.
abstract: Rifampicin is a macrocyclic antibiotic which is used extensively for treatment against Mycobacterium tuberculosis and other mycobacterial infections. Recently, a number of studies have focused on the immune-regulatory effects of rifampicin. Therefore, we hypothesized that rifampicin may influence the TLR2 expression in LPS-activated RAW 264.7 cells. In this study, we determined that rifampicin suppresses LPS-induced TLR2 mRNA expression. The down-regulation of TLR2 expression coincided with decreased production of TNF-alpha. Since NF-kappaB is a major transcription factor that regulates genes for TLR2 and TNF-alpha, we examined the effect of rifampicin on the LPS-induced NF-kappaB activation. Rifampicin inhibited NF-kappaB DNA-binding activity in LPS-activated RAW 264.7 cells, while it did not affect IKKalpha/beta activity. However, rifampicin slightly inhibited the nuclear translocation of NF-kappaB p65. In addition, rifampicin increased physical interaction between pregnane X receptor, a receptor for rifampicin, and NF-kappaB p65, suggesting pregnane X receptor interferes with NF-kappaB binding to DNA. Taken together, our results demonstrate that rifampicin inhibits LPS-induced TLR2 expression, at least in part, via the suppression of NF-kappaB DNA-binding activity in RAW 264.7 cells. Thus, the present results suggest that the rifampicin-mediated inhibition of TLR2 via the suppression of NF-kappaB DNA-binding activity may be a novel mechanism of the immune-suppressive effects of rifampicin.
authors.affiliation: Institute of Hansen's Disease, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea.
authors.forename: Seong Keun
authors.initials: SK
authors.lastname: Kim
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Kim
authors.forename: Chung Eun
authors.initials: CE
authors.lastname: Yeum
authors.forename: Song-Hyo
authors.initials: SH
authors.lastname: Jin
authors.forename: Gue Tae
authors.initials: GT
authors.lastname: Chae
authors.forename: Seong-Beom
authors.initials: SB
authors.lastname: Lee