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The formyl peptide receptor like-1 and scavenger receptor MARCO are involved in glial cell activation in bacterial meningitis.

Braun BJ, Slowik A, Leib SL, Lucius R, Varoga D, Wruck CJ, Jansen S, Podschun R, Pufe T, Brandenburg LO - J Neuroinflammation (2011)

Bottom Line: Furthermore, we demonstrated a functional interaction between FPRL1 and MARCO in NM-induced signalling by real-time RT-PCR, ERK1/2 phosphorylation and cAMP level measurement and show differences between NM- or SP-induced signal transduction.We propose that NM and SP induce glial cell activation and rCRAMP expression also via FPRL1 and MARCO.Thus the receptors contribute an important part to the host defence against infection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anatomy and Cell Biology, RWTH Aachen University, Germany.

ABSTRACT

Background: Recent studies have suggested that the scavenger receptor MARCO (macrophage receptor with collagenous structure) mediates activation of the immune response in bacterial infection of the central nervous system (CNS). The chemotactic G-protein-coupled receptor (GPCR) formyl-peptide-receptor like-1 (FPRL1) plays an essential role in the inflammatory responses of host defence mechanisms and neurodegenerative disorders such as Alzheimer's disease (AD). Expression of the antimicrobial peptide cathelicidin CRAMP/LL-37 is up-regulated in bacterial meningitis, but the mechanisms underlying CRAMP expression are far from clear.

Methods: Using a rat meningitis model, we investigated the influence of MARCO and FPRL1 on rCRAMP (rat cathelin-related antimicrobial peptide) expression after infection with bacterial supernatants of Streptococcus pneumoniae (SP) and Neisseria meningitides (NM). Expression of FPRL1 and MARCO was analyzed by immunofluorescence and real-time RT-PCR in a rat meningitis model. Furthermore, we examined the receptor involvement by real-time RT-PCR, extracellular-signal regulated kinases 1/2 (ERK1/2) phosphorylation and cAMP level measurement in glial cells (astrocytes and microglia) and transfected HEK293 cells using receptor deactivation by antagonists. Receptors were inhibited by small interference RNA and the consequences in NM- and SP-induced Camp (rCRAMP gene) expression and signal transduction were determined.

Results: We show an NM-induced increase of MARCO expression by immunofluorescence and real-time RT-PCR in glial and meningeal cells. Receptor deactivation by antagonists and small interfering RNA (siRNA) verified the importance of FPRL1 and MARCO for NM- and SP-induced Camp and interleukin-1β expression in glial cells. Furthermore, we demonstrated a functional interaction between FPRL1 and MARCO in NM-induced signalling by real-time RT-PCR, ERK1/2 phosphorylation and cAMP level measurement and show differences between NM- or SP-induced signal transduction.

Conclusions: We propose that NM and SP induce glial cell activation and rCRAMP expression also via FPRL1 and MARCO. Thus the receptors contribute an important part to the host defence against infection.

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Increased LL-37 protein expression in transfected HEK293 cells. Untransfected or hFPRL1-, hMARCO- or hFPRL1/hMARCO-expressing HEK293 cells were incubated with NM or SP for 24 h. Cells were fixed and labelled with anti-LL-37 antibodies and protein expression was examined by immunofluorescence microscopy. Bisbenzimide was used for nuclear counter-staining (blue). The figures show representative results from one of three independent experiments. Scale bar: 20 μm.
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Figure 9: Increased LL-37 protein expression in transfected HEK293 cells. Untransfected or hFPRL1-, hMARCO- or hFPRL1/hMARCO-expressing HEK293 cells were incubated with NM or SP for 24 h. Cells were fixed and labelled with anti-LL-37 antibodies and protein expression was examined by immunofluorescence microscopy. Bisbenzimide was used for nuclear counter-staining (blue). The figures show representative results from one of three independent experiments. Scale bar: 20 μm.

Mentions: To confirm the real-time RT-PCR results, we examined LL-37 protein expression in transfected HEK293 cells after treatment with NM, SP and fMLF for 24 h using fluorescence microscopy. As shown in Figure 9 in untransfected and in HEK293 cells transfected only with hMARCO, stimulation with either substance did not change the expression of LL-37 protein. In hFPRL1-transfected cells, fMLF induced a strong, and NM a weak, LL-37 protein expression, whereas in hFPRL1 and hMARCO co-transfected cells treatment with NM and fMLF showed a clear increase of LL-37 expression.


The formyl peptide receptor like-1 and scavenger receptor MARCO are involved in glial cell activation in bacterial meningitis.

Braun BJ, Slowik A, Leib SL, Lucius R, Varoga D, Wruck CJ, Jansen S, Podschun R, Pufe T, Brandenburg LO - J Neuroinflammation (2011)

Increased LL-37 protein expression in transfected HEK293 cells. Untransfected or hFPRL1-, hMARCO- or hFPRL1/hMARCO-expressing HEK293 cells were incubated with NM or SP for 24 h. Cells were fixed and labelled with anti-LL-37 antibodies and protein expression was examined by immunofluorescence microscopy. Bisbenzimide was used for nuclear counter-staining (blue). The figures show representative results from one of three independent experiments. Scale bar: 20 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3040686&req=5

Figure 9: Increased LL-37 protein expression in transfected HEK293 cells. Untransfected or hFPRL1-, hMARCO- or hFPRL1/hMARCO-expressing HEK293 cells were incubated with NM or SP for 24 h. Cells were fixed and labelled with anti-LL-37 antibodies and protein expression was examined by immunofluorescence microscopy. Bisbenzimide was used for nuclear counter-staining (blue). The figures show representative results from one of three independent experiments. Scale bar: 20 μm.
Mentions: To confirm the real-time RT-PCR results, we examined LL-37 protein expression in transfected HEK293 cells after treatment with NM, SP and fMLF for 24 h using fluorescence microscopy. As shown in Figure 9 in untransfected and in HEK293 cells transfected only with hMARCO, stimulation with either substance did not change the expression of LL-37 protein. In hFPRL1-transfected cells, fMLF induced a strong, and NM a weak, LL-37 protein expression, whereas in hFPRL1 and hMARCO co-transfected cells treatment with NM and fMLF showed a clear increase of LL-37 expression.

Bottom Line: Furthermore, we demonstrated a functional interaction between FPRL1 and MARCO in NM-induced signalling by real-time RT-PCR, ERK1/2 phosphorylation and cAMP level measurement and show differences between NM- or SP-induced signal transduction.We propose that NM and SP induce glial cell activation and rCRAMP expression also via FPRL1 and MARCO.Thus the receptors contribute an important part to the host defence against infection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anatomy and Cell Biology, RWTH Aachen University, Germany.

ABSTRACT

Background: Recent studies have suggested that the scavenger receptor MARCO (macrophage receptor with collagenous structure) mediates activation of the immune response in bacterial infection of the central nervous system (CNS). The chemotactic G-protein-coupled receptor (GPCR) formyl-peptide-receptor like-1 (FPRL1) plays an essential role in the inflammatory responses of host defence mechanisms and neurodegenerative disorders such as Alzheimer's disease (AD). Expression of the antimicrobial peptide cathelicidin CRAMP/LL-37 is up-regulated in bacterial meningitis, but the mechanisms underlying CRAMP expression are far from clear.

Methods: Using a rat meningitis model, we investigated the influence of MARCO and FPRL1 on rCRAMP (rat cathelin-related antimicrobial peptide) expression after infection with bacterial supernatants of Streptococcus pneumoniae (SP) and Neisseria meningitides (NM). Expression of FPRL1 and MARCO was analyzed by immunofluorescence and real-time RT-PCR in a rat meningitis model. Furthermore, we examined the receptor involvement by real-time RT-PCR, extracellular-signal regulated kinases 1/2 (ERK1/2) phosphorylation and cAMP level measurement in glial cells (astrocytes and microglia) and transfected HEK293 cells using receptor deactivation by antagonists. Receptors were inhibited by small interference RNA and the consequences in NM- and SP-induced Camp (rCRAMP gene) expression and signal transduction were determined.

Results: We show an NM-induced increase of MARCO expression by immunofluorescence and real-time RT-PCR in glial and meningeal cells. Receptor deactivation by antagonists and small interfering RNA (siRNA) verified the importance of FPRL1 and MARCO for NM- and SP-induced Camp and interleukin-1β expression in glial cells. Furthermore, we demonstrated a functional interaction between FPRL1 and MARCO in NM-induced signalling by real-time RT-PCR, ERK1/2 phosphorylation and cAMP level measurement and show differences between NM- or SP-induced signal transduction.

Conclusions: We propose that NM and SP induce glial cell activation and rCRAMP expression also via FPRL1 and MARCO. Thus the receptors contribute an important part to the host defence against infection.

Show MeSH
Related in: MedlinePlus