Rickettsia rickettsii infection of cultured human endothelial cells induces NF-κB activation

Lee Ann Sporn, Sanjeev K. Sahni, Norma B. Lerner, Victor J. Marder, David J. Silverman, Loel C. Turpin, Amy L. Schwab

Research output: Contribution to journalArticle

54 Scopus citations

Abstract

Rickettsia rickettsii, the etiologic agent of Rocky Mountain spotted fever, is an obligate intracellular bacterial organism that infects primarily the vascular endothelial cells (EC). A component of the EC response to infection is transcriptional activation, which may contribute to the thrombotic and inflammatory consequences of disease. In this study, we explore R. rickettsii-induced activation of the nuclear factor-κB/Rel (NF- κB) family of transcription factors involved in early transcriptional responses to injurious stimuli. Two NF-κB species were activated by infection and reacted with a double-stranded oligonucleotide probe corresponding to the κB binding domain of the murine kappa light-chain gene enhancer. Gel supershift analysis demonstrated the reactivity of these complexes with antibodies against p65 and p50, and the induced species were tentatively identified as p50-p50 homodimers and p50-p65 heterodimers. Semiquantitative reverse transcription-PCR analysis revealed dramatic increases in the steady-state levels of mRNA coding for the inhibitory subunit of NF-κB (IκBα), transcription of which is enhanced by the binding of NF-κB within the IκBα promoter region. NF-κB activation was first detected 1.5 h following infection and was biphasic, with an early peak of activation at approximately 3 h, a return to baseline levels at 14 h, and even higher levels of activation at 24 h. It is likely that NF-κB activation requires cellular uptake of R. rickettsii, since treatment of EC with cytochalasin B during infection to block entry inhibited activation by only 70% at 3 h. R. rickettsii-induced activation of NF-κB may be an important controlling factor in the transcriptional responses of EC to infection with this obligate intracellular organism.

Original languageEnglish (US)
Pages (from-to)2786-2791
Number of pages6
JournalInfection and immunity
Volume65
Issue number7
StatePublished - Jul 4 1997
Externally publishedYes

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases

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    Sporn, L. A., Sahni, S. K., Lerner, N. B., Marder, V. J., Silverman, D. J., Turpin, L. C., & Schwab, A. L. (1997). Rickettsia rickettsii infection of cultured human endothelial cells induces NF-κB activation. Infection and immunity, 65(7), 2786-2791.