A newly established in vitro culture using transgenic Drosophila reveals functional coupling between the phospholipase A2-generated fatty acid cascade and lipopolysaccharide-dependent activation of the immune deficiency (imd) pathway in insect immunity

Masashi Yajima, Masatoshi Takada, Nahoko Takahashi, Haruhisa Kikuchi, Shunji Natori, Yoshiteru Oshima, Shoichiro Kurata

Research output: Contribution to journalArticlepeer-review

77 Citations (Scopus)

Abstract

Innate immunity is the first line of defence against infectious micro-organisms, and the basic mechanisms of pathogen recognition and response activation are evolutionarily conserved. In mammals, the innate immune response in combination with antigen-specific recognition is required for the activation of adaptive immunity. Therefore, innate immunity is a pharmaceutical target for the development of immune regulators. Here, for the purpose of pharmaceutical screening, we established an in vitro culture based on the innate immune response of Drosophila. The in vitro system is capable of measuring lipopolysaccharide (LPS)-dependent activation of the immune deficiency (imd) pathway, which is similar to the tumour necrosis factor signalling pathway in mammals. Screening revealed that well-known inhibitors of phospholipase A2 (PLA2), dexamethasone (Dex) and p-bromophenacyl bromide (BPB) inhibit LPS-dependent activation of the imd pathway. The inhibitory effects of Dex and BPB were suppressed by the addition of an excess of three (arachidonic acid, eicosapentaenoic acid and γ-linolenic acid) of the fatty acids so far tested. Arachidonic acid, however, did not activate the imd pathway when used as the sole agonist. These findings indicate that PLA2 participates in LPS-dependent activation of the imd pathway via the generation of arachidonic acid and other mediators, but requires additional signalling from LPS stimulation. Moreover, PLA2 was activated in response to bacterial infection in Sarcophaga. These results suggest a functional link between the PLA2-generated fatty acid cascade and the LPS-stimulated imd pathway in insect immunity.

Original languageEnglish
Pages (from-to)205-210
Number of pages6
JournalBiochemical Journal
Volume371
Issue number1
DOIs
Publication statusPublished - 2003 Apr 1

Keywords

  • Host defence
  • Innate immunity
  • Nuclear factor κB (NF-κB)
  • Tumour necrosis factor (TNF)

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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