0094. Monocyte tace activity profile during sepsis and systemic inflammatory response syndrome
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KeywordsTace Systemic Inflammatory Response Syndrome Fluorescence Resonance Energy Transfer Tace Activity TNFR Expression
To date, immune-modulatory treatments in sepsis have proved unsuccessful. Better understanding of inflammatory processes might help tailor such therapies more effectively and improve their efficacy. It is now recognised that some patients may require immune stimulating therapies.
Monocytes display altered behaviour in response to systemic inflammation; this has been called “deactivation” and is characterised by reduced HLA-DR expression and attenuated tumour necrosis factor-α (TNF) release in response to lipopolysaccharide (LPS) stimulus1. TNF converting enzyme (TACE), activated via p38-mitogen activated protein kinase (MAPK) mediated pathway2, is essential for the shedding of TNF and TNF receptors (TNFRs)-1&2. Altered TACE behaviour may be mechanistically important in deactivation.
To determine whether monocyte TACE activity is affected by sepsis and is reflective of illness severity.
HLA-DR expression and LPS-induced monocyte TNF release were attenuated in sepsis and NI-SIRS (p< 0.01), consistent with deactivation. Sepsis, but not NI-SIRS, produced elevated basal monocyte TACE activity (p< 0.01) while LPS-induced increases in TACE activity were attenuated. Elevated D0 basal TACE activity positively correlated with APACHE II score in sepsis (p< 0.01), but not NI-SIRS.
TACE expression was unaltered across all groups, but LPS-induced TNFR shedding appeared reduced by sepsis. Sepsis patients displayed an attenuated p38-MAPK response to LPS.
Our data indicate that sepsis induces specific changes in monocyte TACE catalytic activity profiles that may reflect illness severity, whilst such changes were not seen in NI-SIRS. These changes in TACE activity attenuated LPS-induced release of TNFR and TNF from monocytes, and appear to be mediated through altered upstream p38-MAPK signalling.
UK Intensive Care Foundation Young Investigator Award.
- 2.Scott AJ, O'Dea KP, O'Callaghan D, Williams L, Dokpesi JO, Tatton L, Handy JM, Hogg PJ, Takata M: Reactive oxygen species and p38 mitogen-activated protein kinase mediate tumor necrosis factor a-converting enzyme (TACE/ADAM-17) activation in primary human monocytes. J Biol Chem. 2011,286(41):35466–35476. 10.1074/jbc.M111.277434PubMedCentralPubMedCrossRefGoogle Scholar
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