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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

Abstract

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.

References

  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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