Background: Calcific aortic valve disease (CAVD) is a chronic inflammatory condition and the inflammatory responses of aortic valve interstitial cells (AVICs) play a critical role in the disease progression. Double-stranded RNA (dsRNA) released from damaged or stressed cells is pro-inflammatory and may contribute to the mechanism of chronic inflammation observed in diseased aortic valves. The objective of this study is to determine the effect of dsRNA on AVIC inflammatory responses and the underlying mechanism. Methods and results: AVICs from normal human aortic valves were stimulated with polyinosinic-polycytidylic acid [poly(I:C)], a mimic of dsRNA. Poly(I:C) increased the production of interleukin(IL)-6, IL-8, monocyte chemoattractant protein-1 (MCP-1) and intercellular adhesion molecule-1 (ICAM-1). Poly(I:C) also induced robust activation of extracellular signal-regulated protein kinases 1/2 (ERK1/2) and nuclear factor-kappaB (NF-B). Knockdown of Toll-like receptor (TLR) 3 or Toll-interleukin 1 receptor domain-containing adapter-inducing interferon-β (TRIF) suppressed ERK1/2 and NF-B p65 phosphorylation, and reduced inflammatory mediator production induced by poly(I:C). Inhibition of NF-B, not ERK1/2, reduced inflammatory mediator production in AVICs exposed to poly(I:C). Interestingly, inhibition of NF-B by prevention of p50 migration failed to suppress inflammatory mediator production. NF-B p65 intranuclear translocation induced by TLR4 agonist was reduced by inhibition of p50 migration, however, poly(I:C)-induced p65 translocation was not although the p65/p50 heterodimer is present in AVICs. Conclusion: Poly(I:C) up-regulates the production of multiple inflammatory mediators through the TLR3-TRIF-NF-B pathway in human AVICs. The NF-B activated by dsRNA appears not the canonical p65/p50 heterodimers.