IRF5 is involved in transcriptional regulation of TNF. (A) MDDCs were transfected with siRNAs targeting IRF5 (siIRF5), RelA (siRelA), or both [si(IRF5+RelA)] and stimulated with LPS (10 ng/mL) for the indicated time. TNF mRNA expression was compared with control cells transfected with nontargeting siRNA (siC). Data shown are the means ± SD and are representative of 4 independent experiments each using MDDCs derived from a different donor. (B) HEK-293 cells were cotransfected with the TNF 5′wt/3′wt reporter plasmid and equal amounts of expression plasmids encoding for human IRF5, RelA, IRF3, or empty vector (pBent). At 48 hours after transfection, cells were harvested and luciferase activity was measured as described. Data are presented as a fold over pBent ± SEM from 4 independent experiments. *P < .05; ** P < .01 (1-way ANOVA).