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FRI0026 Interleuikin-32 induces tnfalpha and type i interferon via proteinase 3 - protease activated receptor 2-tir-domain-containing adapter-inducing interferon-beta axis
  1. M. Nakayama1,
  2. Y. Niki1,
  3. T. Kawasaki1,
  4. Y. Takeda1,
  5. Y. Toyama1,
  6. T. Miyamoto1
  1. 1Orthopaedic Surgery, Keio University, Tokyo, Japan


Background Interleukin (IL)-32 is known to exert adujvant effects on innate immune response and has an important role in inflammatory disease, such as rheumatoid arthritis [1]. However, receptors and downstream signaling pathways remain to be clarified, except for a role of proteinase 3 (PR3)-binding protein [2]. Although it was also speculated that protease activated receptor-2 (PAR2) mediated the activity of IL-32 through PR3 [3], there is a paucity of reports dealing with the relationship between IL-32 and PAR2.

Objectives We have investigated about the potential signaling pathway of IL-32-TNFα or type I interferon axis was analyzed in vitro.

Methods Using THP-1 cells, in vitro effect of exogenous IL-32γ on TNFα or IFN-β, one of the type I interferon, production was assessed with or without PMSF, inhibitor for serine proteases. And it was also assessed with or without siRNA against PR3 or PAR2. In another experiments, siRNA against TIR-domain-containing adapter-inducing interferon-beta (TRIF), downstream signaling of PAR2 [4], or TRIF-related adaptor molecule (TRAM), which was the molecule recruited by TLR4 to bind TRIF [5], was administered to THP-1 with IL-32γ and TNFα or IFN-β production was assessed.

Results In human monocyte cell line, THP-1 cells, exogenous IL-32γ alone was capable of stimulating TNFα and IFN-β production, which was markedly diminished by either addition of PMSF or siRNA against PR3 or PAR2. Furthermore, siRNA against TRIF, but not TRAM, also hampered IL-32γ-induced TNFα or IFN-β production. Collectively, IL-32-PR3 interaction may be profoundly bound to PAR2-TRIF axis, not TLR4-TRAM-TRIF axis, followed by robust TNFα and IFN-β production, since PAR2 reportedly sensed serine proteases such as PR3.

Conclusions IL-32 induces TNFα and type I interferon via PR3-PAR2-TRIF axis and may play an important role in inflammatory disease.


  1. Kim SH, et al. Interleukin-32: a cytokine and inducer of TNF-alpha. Immunity, 22, 131-142 (2005).

  2. Novick D, et al. Proteinase 3 is an IL-32 binding protein. Proc Natl Acad Sci U S A, 103, 3316-3321 (2006).

  3. Dinarello CA, et al. IL-32, a novel cytokine with a possible role in disease. Ann Rheum Dis. 65 Suppl 3:iii61- iii64 (2006).

  4. Rallabhandi P, et al. Analysis of proteinase-activated receptor 2 and TLR4 signal transduction: a novel paradigm for receptor cooperativity. J Biol Chem 283:24314-24325 (2008).

  5. Yamamoto M, et al. TRAM is specifically involved in the Toll-like receptor 4-mediated MyD88-independent signaling pathway. Nat Immunol 4: 1144-1150 (2003).

Disclosure of Interest None Declared

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