Discordant reprogramming of LPS-Stimulated cytokine gene transcription and secretion by macrophages after LPS pretreatment

Dysregulated macrophage (M phi) cytokine release occurs during systemic inflammation and may predispose to organ failure. We showed that M phi s pretreated (PreRx) in vitro with low-dose LPS(p) are ''reprogrammed'' to release less TNF and more IL-1 in response to subsequent LPS activation (LPS(a)). The effects of this LPS(p) ''reprogramming'' on M phi cytokine gene transcription were investigated in the present study. Murine peritoneal exudate M phi s were cultured in vitro 48 hr, then PreRx 24 hr +/- 100 ng/ml of LPS(p). Cultures were stimulated with 0-1000 ng/ml LPS(a) and 6-hr supernatant TNF and IL-1 were measured using specific bioassays. Cytokine gene transcription was estimated 6 hr after LPS(a) using RT-PCR. PreRx with LPS(p) inhibited TNF and augmented IL-1 release by LPS(a). PreRx with LPS, significantly inhibited cytokine gene transcription; however, messages for both TNF and IL-1 were detectable after high-dose LPS(a). Despite LPS(p) inhibition of IL-1 transcription by most LPS(a) concentrations, IL-1 protein was augmented by PreRx. High-dose LPS(a) can override LPS(p) reprogrammed inhibition of cytokine gene transcription, but altered TNF and IL-1 protein release after LPS(p) may be regulated posttranscriptionally. (C) 1996 Academic Press, Inc.