Expression and regulation of antimicrobial peptide rCRAMP after bacterial infection in primary rat meningeal cells

Brandenburg, Lars-Ove; Varoga, Deike; Nicolaeva, Nicoletta; Leib, Stephen L.; Podschun, Rainer; Wruck, Christoph J.; Wilms, Henrik; Lucius, Ralph; Pufe, Thomas

doi:10.1016/j.jneuroim.2009.10.004

« Previous Next »Journal of Neuroimmunology
Volume 217, Issue 1 , Pages 55-64, 10 December 2009

Expression and regulation of antimicrobial peptide rCRAMP after bacterial infection in primary rat meningeal cells

Lars-Ove Brandenburg
- Department of Anatomy and Cell Biology, RWTH Aachen University, Germany
- Department of Anatomy, University of Kiel, Germany
- Corresponding author. Department of Anatomy and Cell Biology, RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany. Tel.: +49 241 8089548; fax: +49 241 8082431.
Deike Varoga
- Department of Trauma, University Hospital Schleswig-Holstein, Campus Kiel, Germany
Nicoletta Nicolaeva
- Department of Anatomy, University of Kiel, Germany
Stephen L. Leib
- Institute for Infectious Diseases, University of Bern, Switzerland
Rainer Podschun
- Institute of Infection Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Germany
Christoph J. Wruck
- Department of Anatomy and Cell Biology, RWTH Aachen University, Germany
Henrik Wilms
- Department of Neurology, University Hospital Schleswig-Holstein, Campus Kiel, Germany
Ralph Lucius
- Department of Anatomy, University of Kiel, Germany
- These authors contributed equally to this article.
Thomas Pufe
- Department of Anatomy and Cell Biology, RWTH Aachen University, Germany
- These authors contributed equally to this article.

Received 26 June 2009; received in revised form 17 September 2009; accepted 8 October 2009. published online 02 November 2009.

Abstract

Bacterial meningitis is characterized by an inflammation of the meninges and continues to be an important cause of mortality and morbidity. Meningeal cells cover the cerebral surface and are involved in the first interaction between pathogens and the brain. Little is known about the role of meningeal cells and the expression of antimicrobial peptides in the innate immune system. In this study we characterized the expression, secretion and bactericidal properties of rat cathelin-related antimicrobial peptide (rCRAMP), a homologue of the human LL-37, in rat meningeal cells after incubation with different bacterial supernatants and the bacterial cell wall components lipopolysaccharide (LPS) and peptidoglycan (PGN). Using an agar diffusion test, we observed that supernatants from meningeal cells incubated with bacterial supernatants, LPS and PGN showed signs of antimicrobial activity. The inhibition of rCRAMP expression using siRNA reduced the antimicrobial activity of the cell culture supernatants. The expression of rCRAMP in rat meningeal cells involved various signal transduction pathways and was induced by the inflammatory cytokines interleukin-1, -6 and tumor necrosis factor alpha. In an experimental model of meningitis, infant rats were intracisternally infected with Streptococcus pneumoniae and rCRAMP was localized in meningeal cells using immunohistochemistry. These results suggest that cathelicidins produced by meningeal cells play an important part in the innate immune response against pathogens in CNS bacterial infections.

Abbreviations: rCRAMP, rat cathelin-related antimicrobial peptide, CSF, cerebrospinal fluid, BBB, blood brain barrier, ERK, extracellular signal-regulated kinases, DMEM, Dulbecco's modified Eagle's medium, FCS, fetal calf serum, SFM, serum free medium