Annexin A5 binds to lipopolysaccharide and reduces its endotoxin activity

Jacob H. Rand, Xiao Xuan Wu, Elaine Y. Lin, Alexander Griffel, Philip Gialanella, John C. McKitrick

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Annexin A5 (AnxA5) has a high affinity for phosphatidylserine. The protein is widely used to detect apoptotic cells because phosphatidylserine, a phospholipid that is normally present in the inner leaflets of cytoplasmic membranes, becomes translocated to the outer leaflets during programmed cell death. Here we report the novel observation that AnxA5 binds to Gram-negative bacteria via the lipid A domain of lipopolysaccharide (LPS). Binding of AnxA5 to bacteria was measured quantitatively, confirmed by fluorescence microscopy, and found to be inhibited by antibodies against lipid A. AnxA5 also bound to purified dot-blotted LPS and lipid A. Through ellipsometry, we found that the binding of AnxA5 to purified LPS was calcium dependent and rapid and showed a high affinity- characteristics similar to those of AnxA5 binding to phosphatidylserine. Initial functional studies indicated that AnxA5 can affect LPS activities. AnxA5 inhibited LPS-mediated gelation in the Limulus amebocyte lysate assay. Incubation of LPS with the protein reduced the quantity of tumor necrosis factor alpha (TNF-α) released by cultured monocytes compared to that released upon incubation with LPS alone. Initial in vivo experiments indicated that injection of mice with LPS preincubated with AnxA5 produced serum TNF-αlevels lower than those seen after injection of LPS alone. These data demonstrate that AnxA5 binds to LPS and open paths to investigation of the potential biological and therapeutic implications of this interaction.

Original languageEnglish (US)
Article numbere00292-11
Issue number2
StatePublished - 2012
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Virology


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