Fig 6.

iNOS inhibition reverses the DCP-mediated antimycobacterial effects. (A) The addition of the iNOS inhibitor (l-NMMA monoacetate) markedly reversed the DCP-mediated inhibition of intracellular M. bovis BCG growth. **, P = 0.0022 for untreated infected monocytes versus DCP-treated infected monocytes; **, P = 0.0022 for DCP-treated infected monocytes versus DCP-treated infected monocytes plus 1 mM l-NMMA monoacetate. n.s., P = 0.0649. P values were obtained using Mann-Whitney U tests. (B and C) Effects of addition of l-NMMA to infected monocytes without DCP. Monocytes were obtained from PBMCs of 6 different donors (**, P = 0.0079). (D) Uninfected or BCG-infected human monocytes were cultured with or without DCP at 37°C. After 12 h of culture, total cellular RNA was isolated and IDO1 mRNA expression measured by real-time RT-PCR. Data shown are means ± standard errors of the means of fold gene expression in monocytes obtained from 6 different volunteers. DCP moderately induced IDO1 expression in uninfected macrophages. In vitro infection by M. bovis BCG induced monocytes to express greater amounts of IDO1, which was suppressed by treatment with DCP. Significant differences in mean IDO1 levels were detected in the following comparisons: uninfected without DCP versus uninfected with DCP (**, P = 0.0037), uninfected with DCP versus BCG infected without DCP (*, P = 0.0152) and BCG infected without DCP versus BCG infected with DCP (*, P = 0.0411). P values were obtained using Mann-Whitney U tests.