Novel markers of inflammation identified in tumor necrosis factor receptor-associated periodic syndrome (TRAPS) by transcriptomic analysis of effects of TRAPS-associated tumor necrosis factor receptor type I mutations in an endothelial cell line

TRAPS-associated TNFRI mutants induce the expression of multiple genes encoding inflammatory molecules, cellular receptors, transcription factors, and regulators of apoptosis in endothelial cells that require the cytoplasmic signaling properties of the receptor. Different mutants have specific expression profiles, indicating mutation-specific effects. The expression of some of these markers was also elevated in samples from TRAPS patients.

Transcriptome analysis on 30,000 human genes was performed on SK-Hep-1 human endothelial cells transfected with either wild-type (WT) or TRAPS-associated mutant TNFRI. Quantitative reverse transcriptase-polymerase chain reaction and protein expression levels measured by enzyme-linked immunosorbent assay verified transcriptional changes for selected genes both in supernatants from cells expressing mutant TNFRI and in patient plasma.

To analyze the effects of tumor necrosis factor receptor-associated periodic syndrome (TRAPS)-associated mutant tumor necrosis factor receptor type I (TNFRI) expression in a cell type directly relevant to the inflammation in TRAPS, and to identify novel markers associated with mutant TNFRI expression.

Cells expressing mutant TNFRI showed up-regulation of multiple proinflammatory genes relative to WT transfectants, including genes for pentraxin 3, granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, CCL2, and CCL5, which were also expressed as proteins. In addition, the expression of most of these markers was increased in the plasma and peripheral blood mononuclear cells from TRAPS patients relative to those from healthy controls. The cysteine mutations (C33Y and C52F), which are associated with a more severe clinical phenotype, induced more genes than the low-penetrance mutation R92Q, which is associated with a milder phenotype. The expression of most genes was induced by a death domain (DD)-dependent mechanism, since they were not induced by expression of TNFRI mutants with an inactivated DD.