Salmonella enterica serovar Typhimurium-induced internalization and IL-8 expression in HeLa cells does not have a direct relationship with intracellular Ca2+ levels

Josely F. Figueiredo, Rola Barhoumi, Manuela Raffatellu, Sara D. Lawhon, Bernard Rousseau, Robert C. Burghardt, Renee M Tsolis, Andreas J Baumler, L. Garry Adams

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

The invasion-associated type III secretion system (T3SS-1) of S. Typhimurium is required to initiate and sustain an acute inflammatory response in the intestine. We investigated the relationship of S. Typhimurium T3SS-1-induced IL-8 expression and invasion with intracellular Ca2+ mobilization in HeLa cells. Compared to the sipAsopABDE2 mutant, strains carrying a mutation in sipA, or mutations in sopABDE2 induced higher levels of IL-8 and greater bacterial internalization despite the fact that these mutants elicited similarly low intracellular concentrations of Ca2+. Likewise, complemented sipAsopABDE2 mutant with sopE2 did not affect intracellular Ca2+ concentrations or IL-8 expression, but significantly increased bacterial internalization. Treating HeLa cells with the calcium chelator BAPTA-AM or with D-BAPTA-AM, a derivative with greatly reduced Ca2+ chelating activity, yielded strong evidence that BAPTA-AM does not affect invasion and inhibits IL-8 secretion by a calcium-dependent mechanism. These findings suggest that, although wild-type S. Typhimurium-induced IL-8 expression and bacterial internalization in HeLa cells coincides with increased cytosolic Ca2+, the differing levels of IL-8 and invasion induced by strains carrying different effector proteins are unrelated to levels of intracellular Ca2+.

Original languageEnglish (US)
Pages (from-to)850-858
Number of pages9
JournalMicrobes and Infection
Volume11
Issue number10-11
DOIs
StatePublished - Sep 2009

Keywords

  • Calcium
  • IL-8
  • Salmonella enterica serovar Typhimurium
  • SipA
  • T3SS-1

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Infectious Diseases

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